Volume 48,2026 Issue 1

土木工程

• Machine learning-based investigation of uplift resistance in special-shaped shield tunnels using numerical finite element modeling

  ZHANG Wengang, YE Wenyu, SUN Weixin, LIU Zhicheng, LI Zhengchuan

  2026,48(1):1-13, DOI: 10.11835/j.issn.2096-6717.2024.024

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  The uplift resistance of the soil overlying shield tunnels significantly impacts their anti-floating stability. However, research on uplift resistance concerning special-shaped shield tunnels is limited. This study combines numerical simulation with machine learning techniques to explore this issue. It presents a summary of special-shaped tunnel geometries and introduces a shape coefficient. Through the finite element software, Plaxis3D, the study simulates six key parameters—shape coefficient, burial depth ratio, tunnel’s longest horizontal length, internal friction angle, cohesion, and soil submerged bulk density—that impact uplift resistance across different conditions. Employing XGBoost and ANN methods, the feature importance of each parameter was analyzed based on the numerical simulation results. The findings demonstrate that a tunnel shape more closely resembling a circle leads to reduced uplift resistance in the overlying soil, whereas other parameters exhibit the contrary effects. Furthermore, the study reveals a diminishing trend in the feature importance of buried depth ratio, internal friction angle, tunnel longest horizontal length, cohesion, soil submerged bulk density, and shape coefficient in influencing uplift resistance.

• Mechanical properties and crack propagation mechanism of non-through jointed sandy slate in triaxial unloading test

  WANG Lehua, XU Jianwen, CHEN Can, GUO Jinfan, XU Xiaoliang

  2026,48(1):14-23, DOI: 10.11835/j.issn.2096-6717.2023.146

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  During excavation and unloading of underground chambers, the mechanical characteristics and crack propagation behavior of jointed rock formations are vital for project safety and stability. This study focuses on the jointed sandy slate in the underground powerhouse of the Kala Hydropower Station in Sichuan, and conducts series of tests on non-penetrating jointed sandy slate under triaxial loading and unloading conditions. We analyzed the mechanical properties and deformation characteristics under different stress paths, explored the applicability of various strength criteria, and investigated crack propagation mechanisms using fracture mechanics. It is found that: (1) As initial confining pressure increases, axial stress and strain at failure show an upward trend under different stress paths. (2) Compared to triaxial loading, unloading paths and jointed samples decrease load-bearing capacity. Unloading from axial stress to confining pressure increases cohesion by 4.1% and unloading from confining pressure to axial stress decreases it by 30.4%. The internal friction angle increases by 3.5% and 7.3% during axial compression, while jointed samples, compared with intact samples, show a decrease of 32.9% and 53% in cohesion and a decrease of 2.2% and 10% in internal friction angle respectively. (3) In terms of characterizing the strength properties of sandy slate throughout the loading and unloading processes, the Mogi-Coulomb strength criterion outperforms both the Mohr-Coulomb and Drucker-Prager criteria. (4) The theoretical critical angle increases with confining pressure, and biconjoint samples exhibit higher values than intact ones. The theoretical critical angles range from 55° to 60° under different loading paths.

• Simplified method for thickness design of ecological soil covers in northwest China

  LI Guangyao, ZHAN Liangtong, JIAO Weiguo, FENG Song, CHEN Yunmin

  2026,48(1):24-35, DOI: 10.11835/j.issn.2096-6717.2023.135

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  Currently, the thickness design method for ecological soil covers used in northwest China is based on the practice of non-humid regions in north America, which is complicated, involves various parameters, and fails to consider the different meteorological conditions between northwest China and north America. To solve this issue, on the basis of the monsoon climate of northwest China, the feature that the precipitation during the non-growing period of vegetation should not exceed 20% of the total annual precipitation, as well as the water retention characteristics of ideal cover soils that the ratio of the field capacity to the wilting point K ≥ 1.44, the thickness design method for ecological soil covers used in northwest China is simplified. The numerical program Vadose/W is utilized to analyze the hydraulic responses of the loess monolithic cover and the loess-gravel capillary barrier cover designed with the proposed simplified method in the year of maximum precipitation. The results indicate that the capillary barrier effect significantly prevents the migration of water from the loess layer to the gravel layer, resulting in the capillary barrier cover having better anti-seepage performance than the monolithic cover. The anti-seepage performance of the two covers decreases with the decrease in the ratio of the field capacity to the wilting point of the loess (i.e., K). When K ≥ 1.35, the two covers can meet the local anti-seepage requirements, thus preliminarily verifying the reliability of the proposed simplified method.

• Multi-field information simulation method of reservoir landslide with mutual feedback between GeoStudio and FLAC3D

  WANG Yankun, WEN Tao, WANG Luqi, HU Mingyi, WEI Mengxue

  2026,48(1):36-43, DOI: 10.11835/j.issn.2096-6717.2023.145

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  Accurately obtaining multiple-field information on the reservoir landslide subjected to dynamic water action is an important basis for reliably evaluating landslide stability. To overcome the limitations of GeoStudio and FLAC3D numerical software in simulating multiple-field information of reservoir landslides, this paper proposes a method for simulating multiple-field information of reservoir landslides with mutual feedback between GeoStudio and FLAC3D. This method first simulates the time-varying seepage field of landslides under dynamic water action using GeoStudio and then achieves fast conversion of the GeoStudio model and seepage field to FLAC3D by developing an interface program. Based on the hydrological characteristics of the rock-soil mass and the principle of effective stress, the soil parameters and initial stress in the FLAC3D model are modified to calculate the stress and strain of the landslide. The effectiveness of this method is verified by a large-scale physical model test of a reservoir landslide under a sudden drop in reservoir water level. It can be observed that the simulated evolution trend of multiple-field information of landslides using this method is consistent with the physical model test results. The maximum average simulation error of pore water pressure at monitoring points is less than 10%, and the maximum average simulation error of total stress is within 33%. The simulation results accurately reproduce the traction multiple slip surface failure mode and final slip surface location of the reservoir landslide physical model test.

• Effects of corner-bridge flow on capillary pressure-saturation curve in porous media

  WANG Guanxiong, HU Ran, LAN Tian, CHEN Yifeng

  2026,48(1):44-53, DOI: 10.11835/j.issn.2096-6717.2023.108

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  The capillary pressure curve is a fundamental constitutive relationship for simulating unsaturated flow and water-gas multiphase flow in porous media. As the wetting-phase saturation approaches the residual saturation, corner films and liquid bridges formed between solid grains become the dominant pathways governing fluid displacement processes. At present, the mechanisms by which corner films and liquid bridges influence capillary pressure curves remain insufficiently understood. In this study, a microfluidic visualization experimental platform was developed, and quasi-static drainage experiments were conducted in six sets of microfluidic models with different pore structures and surface roughness. The corner film-liquid bridge flow was directly observed, and its influence on capillary pressure curves was quantitatively evaluated. The results indicate that corner film-liquid bridge flow mainly occurs at low wetting-phase saturations and leads to a reduction in the residual wetting-phase saturation by 0.21-0.32. The occurrence of corner film-liquid bridge flow is closely related to the wettability of the porous medium; rough solid surfaces reduce the contact angle of the wetting phase, thereby facilitating the formation of corner films and liquid bridges. Moreover, the impact of corner film-liquid bridges is positively correlated with the number of liquid bridges, and their effect becomes more pronounced with decreasing porosity and heterogeneity of the porous medium.

• Cracking characteristics of hydroxypropyl methylcellulose modification coral clay

  WANG Hong, DING Xuanming, FANG Xiangwei, FANG Huaqiang, LI Yifu, XIN Yiwen

  2026,48(1):54-62, DOI: 10.11835/j.issn.2096-6717.2024.062

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  For effective use of island reef coral mud, the performance of island reef coral mud was investigated to examine the cracking phenomenon when this coral mud was utilised as engineering material, and it is of practical significance to carry out the research on the cracking and modification of coral mud. Firstly, hydroxypropyl methyl cellulose (HPMC) and coral mud were used to prepare an indoor surface model for the cracking test. Images were captured at different time periods and then the changes in coral mud-related parameters were obtained by image processing techniques; Secondly, the changing patterns of coral mud cracking parameters such as crack development rate and the dynamic evolution patterns of cracks in coral mud after HPMC modification were investigated; Finally, the inhibitory effect of HPMC on the cracking behaviour of coral mud was analysed and the cracking inhibition mechanisms were described. The results of the study show that the addition of HPMC can significantly improve the anti-cracking properties of coral mud soil samples, and HPMC can prevent the contraction of the soil body and inhibit the generation of cracks by reducing the content of free water in the soil samples and adsorbing the coral mud particles inside the soil samples to form agglomerates. This can significantly optimise the overall performance of the coral mud surface layer and its anti-cracking performance.

• Vibration attenuation characteristic of dynamic compaction and effect of damping ditch parameters in a sandy foundation

  CHENG Xuri, TONG Chenxi, WANG Xiaotao, FENG Yushun, ZHANG Sheng

  2026,48(1):63-70, DOI: 10.11835/j.issn.2096-6717.2024.001

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  Dynamic compaction is a widely employed foundation treatment method, but the surface vibrations it incurs can potentially lead to damage in nearby constructions. Therefore, it is crucial to determine appropriate safety distances and implement effective vibration absorption methods based on specific site conditions and vibration attenuation laws. Drawing from the dynamic compaction process at Fuzhou Changle International Airport, we conducted on-site tests to acquire essential data and subsequently performed simulations using the discrete element method. Our findings revealed that, under identical energy levels, lighter hammers result in higher soil velocities. Moreover, heavier hammers exhibit a broader influence and lead to a slower attenuation process. Simulation results demonstrated that the attenuation process can be accurately modeled using hyperbolic functions, a conclusion substantiated by the results of our field experiments. Damping ditch calculations indicated that the vibration velocities of soil increase before the ditch and decrease behind it. Based on relevant standards, the installation of a damping ditch in this area allows for a substantial reduction in the required safety distance.

• Horizontal bearing characteristics of pile foundation in large thickness artificial fill foundation

  LIU Deren, FEI Yan, AN Zhengshan, ZHANG Yanjie, NIU Yaqiang, ZHU Zhechao, GUO Yafang

  2026,48(1):71-79, DOI: 10.11835/j.issn.2096-6717.2023.133

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  In order to explore the horizontal bearing characteristics of pile foundations in large‐thickness artificial fill foundation and the applicability of the m‐method in engineering practice, the field tests of horizontal bearing capacity of single piles and the theoretical calculations of the m‐method are carried out. The variation patterns of displacement and bending moment under horizontal loads are obtained, and the deformation characteristics of pile-soil under horizontal loads are presented. The variation of the proportional coefficient m of the horizontal resistance coefficient of the foundation soil with the load and displacement is further obtained. The results show that with the increase of loading, the horizontal displacement increases continuously, and after reaching the critical value of 480 kN, the horizontal displacement and displacement gradient of pile foundations change drastically. Under the same loading, the bending moment of pile foundations increases first and then decreases with the increase of depth. The bending moment diagram shows the distribution pattern of “small at both ends and large in the middle”. At the same depth, the bending moment increases with the increase of load, and negative bending moment appears at a certain depth. The influence range of bending moment along the depth is about 10 m. The proportional coefficient m of the horizontal resistance coefficient decreases exponentially with the increase of load and displacement. When the load and displacement are small, the m values of the two piles are quite different. When the load and displacement increase to a certain value, the m values of the two piles are close and finally stabilized near a specific value. The calculation results of the m‐method are verified and improved by experimental data. It is found that the maximum displacement calculated by the m‐method is close to the measured results. When the load is small, the calculated maximum bending moment is close to the measured results. After exceeding the critical load, the difference is large, indicating that when the load exceeds the critical value, the maximum bending moment does not show a linear elastic increase. It is necessary to correct the bending moment calculation result by the correction coefficient function β. The corrected bending moment is more consistent with the measured value, indicating that the m‐method works well in engineering practice.

• Field test and numerical simulation on thermal performance of a large-diameter bridge energy pile

  ZHAO Zhipeng, WANG Zhipeng, WU Di, CHEN Rong, KONG Gangqiang

  2026,48(1):80-88, DOI: 10.11835/j.issn.2096-6717.2023.132

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  This study focuses on investigating the heat transfer characteristics of large-diameter bridge energy piles through field tests, aiming to examine the heat exchange rate and temperature distribution of a full-scale large-diameter bridge energy pile and its surrounding soil. Additionally, a three-dimensional numerical model of this energy pile is developed and validated by comparing field measurements with simulation results. With the validated model, a parameter sensitivity analysis is conducted to explore the influence mechanism of convective heat exchange between the bridge piers on top of the pile and the surrounding air on the heat transfer characteristics of the large-diameter bridge energy pile. The results indicate that the heat exchange rate of this energy pile can reach -222.28 W/m, which is approximately 1.5 to 3.9 times that of conventional types. However, the larger diameter of the pile leads to uneven temperature distribution across the cross section. Specifically, the temperature near the heat exchange tubes is significantly higher (by around 3 ℃) than that at the central axis. Furthermore, it is observed that convective heat exchange between the bridge piers and surrounding air causes a decrease in the temperature of the piers, thereby increasing the heat exchange rate of the bridge energy pile in summer operation mode. When the heat transfer mode on the pier surface transitions from natural convection (air flow rate of 0 m/s) to forced convection (air flow rate of 5 m/s), the heat exchange rate of the bridge energy pile increases by approximately 22 W/m.

• Deformation characteristics of soft soil deep foundation pit partitioned excavation

  CHEN Nanqiao, WANG Xuepeng, LIN Gang, XU Changjie, XIONG Yi, CAO Huajin

  2026,48(1):89-99, DOI: 10.11835/j.issn.2096-6717.2024.076

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  In this study, the deep foundation pit project of No.4 Wangjiang New City of Hangzhou New World is taken as a case study, and the zonal excavation process of the foundation pit is comprehensively monitored. Through the in-depth analysis of the monitoring data of the diaphragm wall deformation, soil inclinometer measurements,wall top settlement, and ground settlement outside the pit, and combined with the numerical model of the foundation pit zonal excavation established by PLAXIS 3D, we compare the numerical simulation results with the actual monitoring data to validate the accuracy of the model and to supplement the insufficiency of the monitoring data. The results show that the deformation of the diaphragm wall during the excavation of the foundation pit presents a typical parabolic variation pattern, and a push-back displacement toward the pit occurs during the post-excavation construction stage. The deformation characteristics of the soil outside the pit are similar to those of the diaphragm wall, but its deformation magnitude is relatively small. With the progress of foundation pit excavation, the ground settlement outside the pit increases gradually, and its displacement curve deviates from the traditional parabolic variation pattern due to the influence of environmental factors. In addition, the wall top settlement shows a clear trend of “first heave and then settle” during the foundation pit excavation and the construction of the main structure inside the pit.

• Effect of geosynthetic clay liners overlap on impervious performance of geosynthetic clay liners composite vertical barrier wall

  YANG Shizhao, XIAO Chengzhi, ZANG Nianyong, XIE Shiping, HE Shunhui

  2026,48(1):100-109, DOI: 10.11835/j.issn.2096-6717.2023.139

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  Geosynthetic clay liners (GCL) composite vertical anti-seepage wall, which consists of a cement-bentonite slurry wall and geosynthetic clay liners, is a new type of vertical anti-seepage wall. GCL overlap width and the treatment effect of the overlap area are the important factors that influence the impervious performance of a GCL composite vertical barrier wall. A two-dimensional model for pollutant migration was presented in this study. The study conducted a comprehensive analysis of the impact of various factors, including the width of GCL overlap (B₂), the permeability coefficient of the GCL overlap area (k_p)_, the thickness of the cement-bentonite wall (L_w) and the permeability coefficient of the cement-bentonite wall (k_w), on the transversal distribution of pollutants and the critical GCL overlap width. This analysis was based on a numerical simulation method. The calculation results showed that the bypass effect induced by the GCL overlap area has a significant influence on the anti-seepage performance. Keeping the other parameters identical, when the k_p of the GCL overlap area is reduced from 1.0×10^-6 m/s to 1.0×10^-10 m/s, the critical GCL overlap width decreases considerably from 68.9 cm to 21.1 cm. Increasing L_w leads to a decrease in pollutant concentration at the exit of the overlap area and a reduction in the critical overlap width of the GCL. For example, when L_w is increased from 0.4 to 0.8 m, the breakthrough time is extended by approximately 2.5 times and the critical GCL overlap width is reduced by about 38.5%. Furthermore, when the k_w of the cement-bentonite wall is reduced from 1.0×10^-8 m/s to 5.0×10^-10 m/s, the concentration of pollutant at the exit of the overlap area is decreased by 73.1 % and the critical width of the GCL overlap is reduced by about 33.3%.

• Influence of loading medium on mechanical properties of geomembrane bulging deformation

  LI Zheng, LI Wanglin, WANG Wansheng, YU Hairui, XUE Xia

  2026,48(1):110-117, DOI: 10.11835/j.issn.2096-6717.2023.121

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  In order to find out whether the loading medium has an effect on the mechanical properties of geomembrane bulging deformation, HDPE geomembranes with three thicknesses of 0.2 mm, 0.3 mm and 0.6 mm were selected as the research objects. Using the special test equipment for bulging deformation, we used air and liquid as the loading media respectively. At the injection rate of 1 kPa/s, the spherical bulging deformation test under annular constraints was carried out, and the microscopic morphology changes and differential failure mechanisms of geomembrane bulging failure were emphatically analyzed by means of a polarizing microscope. The results show that under the same environmental conditions, the bursting pressure under liquid bulging is about 34% higher than that under air bulging, and the bulging height under liquid bulging is about 22% higher than that under air bulging. The bulging deformation of geomembranes under air and liquid bulging shows different stages of elastic, yield, strengthening and failure deformation. The geomembrane presents a linear failure surface during air bulging, which is manifested as uniform tensile deformation and fracture of the polymer chain segments at the micro level. The geomembrane presents a banded failure surface during liquid bulging, which is manifested as uneven tensile deformation and fracture of the polymer chain segments at the micro level. The influence of the loading medium on the mechanical properties and failure characteristics of the spherical bulging deformation of the geomembrane is mainly related to the properties of the medium itself, the distribution of pressure load under the membrane and the reorientation and recrystallization of polymer chains. According to the research results, it is recommended to use liquid medium to carry out the strength test for the bulging failure of the geomembrane.

• Shear characteristics of the interface between recycled concrete aggregate and geogrids

  WU Jianqi, LUO Xiang, WANG Jun, LI Min, CHEN Teng

  2026,48(1):118-126, DOI: 10.11835/j.issn.2096-6717.2023.099

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  In the context of ongoing economic development and urban expansion, there is an urgent need to promote the resource utilization and recycling of construction waste. As a crushed material obtained from the screening of construction waste, recycled concrete aggregate has broad application prospects. This study focuses on four distinct particle size ranges of recycled concrete aggregate. By introducing the concept of aperture ratio, the shear characteristics of the interface between the recycled concrete aggregate and biaxial polypropylene geogrids are investigated through large-scale direct shear tests under three different vertical stresses and four different shear rates. The findings demonstrate that as the aperture ratio diminishes, the peak shear stress and residual shear stress at the shear interface increased, and the peak shear stress occurred at a later stage. Conversely,as the aperture ratio decreases, the peak apparent cohesion and residual apparent cohesion undergo a gradual increase, and the peak internal friction angle and residual internal friction angle also increase. The addition of geogrids effectively reduces the occurrence of shear dilation at the interface. By introducing the Kalhaway constitutive equation, the expression for shear stiffness is derived through linear and logarithmic fitting, and the shear stiffness corresponding to the stress state (σ_n,τ) is thereby obtained.

• Change regularity and loading protocol for the axial force of beam-column joints in RC frame structures

  YANG Hong, WANG Ziyan, JIANG Hiu

  2026,48(1):127-141, DOI: 10.11835/j.issn.2096-6717.2024.080

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  The seismic performance of reinforced concrete (RC) beam-column joints is typically determined through constant axial loading experiments. The paucity of research in this field is evidenced by the absence of a reliable variable axial force loading protocol, thus resulting in only a small number of experimental studies on the seismic performance of RC joints considering the influence of variable axial force. Furthermore, all such studies assume that the axial force changes in accordance with a simplified linear method, which is an inadequate reflection of the real mechanical characteristics of beam-column joints in RC frame structures under horizontal earthquake excitations. The present study employs finite element simulation of six plane RC frames of seismic intensity 8 (0.2g) with different layers and spans under monotonic and cyclic loading to investigate the change mechanism of joint axial force under horizontal load, and to identify the influencing factors of the change in joint axial force. On the basis of theoretical analysis and statistical regression, a joint variable axial force loading protocol that is consistent with the characteristics of axial force changes and capable of accounting for the nonlinear behavior of materials has been proposed. The results show that the nonlinear behavior of concrete and reinforcement is the primary cause contributing to the nonlinear changes in joint axial force. Additionally, the tensile yield of longitudinal bars at beam end is identified as the principal factor influencing the regularity of the joint axial force changes. The present formula for calculating the change amplitude of joint axial force is proposed, with consideration given to the effects of the following factors: joint type, total number of structural floors, beam span, beam reinforcement area, and beam sectional dimensions. The skeleton curve of the proposed joint variable axial force loading protocol is capable of more accurately reproducing the characteristics of the gradual slowing down of the joint axial force change rate following the tensile yield of longitudinal reinforcement at the beam end of each floor above the joint. Furthermore, the hysteresis rule is able to account for the influence of the nonlinear behaviour of materials on the degradation of unloading stiffness in a reasonable manner.

• Shear behavior of rib-treated interface between ultra-high performance concrete and normal concrete

  WANG Peng, YOU Xuehui, SHI Qingxuan, TAO Yi

  2026,48(1):142-152, DOI: 10.11835/j.issn.2096-6717.2023.134

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  The present study investigates the interfacial shear performance between ultra-high performance concrete (UHPC) and normal concrete (NC). To this end, 13 UHPC-NC direct shear specimens were designed and fabricated. Through push-out tests, the influence of UHPC rib width, height, and spacing on the interfacial failure mode and shear bearing capacity was discussed. Furthermore, a finite element model of the UHPC-NC specimens was established using the software ABAQUS, and a parameter analysis was conducted. The results indicate that the failure modes of the ribbed UHPC-NC interface mainly include: complete interface failure and UHPC ribs sheared off; partial interface failure and partial failure of NC embedded between UHPC ribs; and partial interface failure and complete failure of NC embedded between UHPC ribs. The specimens with rib widths of 10 mm primarily exhibit the first failure mode, while specimens with rib widths of 15 and 20 mm correspond to the latter two failure modes. It has been demonstrated that the shear capacity and slip of the interface increase with an increase in rib width and spacing, thereby demonstrating enhanced ductility. When the rib width is 10 mm, increasing the rib height has little effect on the shear bearing capacity, while when the rib width is 15 and 20 mm, increasing the rib height can improve the shear bearing capacity. In addition, increasing the number of ribs can improve the shear bearing capacity, but with the increase of the number of ribs, the effectiveness of bearing capacity enhancement significantly decreases.

• Seismic performance of open masonry walls of village and town buildings reinforced with polypropylene mesh-composite cement mortar

  TIAN Penggang, CAO Chenyang, LU Junlong, BIAN Zhaowei, WANG Zhenshan, YUAN Zuoyi

  2026,48(1):153-163, DOI: 10.11835/j.issn.2096-6717.2024.060

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  Surveys of village buildings frequently reveal a paucity of essential seismic measures, resulting in a deficiency in seismic capacity. In order to enhance the seismic capacity of these buildings, it was necessary to reinforce the walls using polypropylene mesh and composite cement mortar. In order to investigate the seismic performance of reinforced masonry walls with openings, three wall models with openings were designed and subjected to quasi-static tests. The hysteresis and skeleton curves of the model specimens were obtained from these tests. Numerical models were then established using ABAQUS finite element software for the purpose of computational analysis. A comparison was then made between the results obtained from this analysis and the experimental findings, which revealed a high degree of consistency. The unreinforced specimens exhibited initial cracking at the corners of the openings under load, which gradually extended to the wall ends, forming “X” or “/\” shaped continuous cracks indicative of shear failure. Reinforcement with polypropylene mesh and composite cement mortar effectively delayed and mitigated wall damage. The ultimate bearing capacity of walls reinforced on one side and both sides increased by 68.75% and 107.05%, respectively, compared to unreinforced walls. Additionally, the initial stiffness of the walls improved by 11.68% and 46.55%, respectively, while the ductility performance increased by 6.34% and 14.63%. The analysis results indicate that both single-side and double-side reinforcement of masonry walls with openings significantly enhance their seismic capacity. The openings tend to form continuous cracks after initial cracking, and the failure mode differs from that of walls without openings.

• Flexural performance of RC beams reinforced with textile reinforced concrete composite embedded prestressed CFRP bars

  LUO Ziqing, LUO Junhui, NING Jiejun, YIN Shiping, LIU Zirui

  2026,48(1):164-173, DOI: 10.11835/j.issn.2096-6717.2023.141

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  The present study investigates the flexural performance of reinforced concrete beams reinforced with TRC composite embedded prestressed CFRP bars.To this end, a four-point flexural load test was carried out on one ordinary reinforced concrete beam and five beams reinfored with TRC composite embedded prestressed CFRP bars. The effects of slot size and diameter of CFRP bars on the flexural performance of the composite reinforced beams, including bearing capacity, failure mode and crack distribution, were analyzed. The test results show that the load increase of the composite reinforced beam is more obvious in each stage than that of the unreinforced beam. The ultimate load of the reinforced beam increases slightly with an increase of slot size and greatly with the increase of CFRP bar diameter. The flexural stiffness of the composite reinforced beam is obviously higher than that of the unreinforced beam. The increase of slot size and diameter of CFRP bars is not proportional to the increase of beam stiffness. The number of cracks in composite reinforced beams is obviously more than that of ordinary reinforced concrete beams, and the cracks show a fine and dense distribution characteristic, and it increases with the increase of slot size, but the diameter of CFRP bars has little effect. The ductility of the unreinforced beam is obviously higher than that of the reinforced beam on it. The ductility of the composite reinforced beam decreases with the increase of the diameter of the CFRP bar, and the increase of the slot size has no obvious effect on the ductility of the beam. Based on the calculation model of the cracking load of a single reinforced concrete beam proposed in the literature, a formula for calculating the cracking load of a composite reinforced concrete beam is proposed. The discrepancy between the calculated value and the test value is less than 6.5%, which indicates that the formula has adequate applicability.

• Intelligent digital construction for complex frame-panel structures based on point cloud data and heuristic algorithms

  LIAO Yue, LI Hantao, LIU Jiepeng, ZENG Yan, LI Laian, MA Xiaoxiao, CUI Na

  2026,48(1):174-183, DOI: 10.11835/j.issn.2096-6717.2023.147

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  In the construction of large and intricate frame-panel structures, the curvature and twists of the backbone present a challenge in the assessment of the installation quality and the attachment of the panels.The classic method for panel detail design is associated with several drawbacks, such as low efficiency and the need for greater automation. In the context of the Nansha International Finance Forum project, we investigated intelligent construction techniques for large and intricate frame-panel structures, based on point cloud data (PCD) and heuristic algorithms. A backward modelling method applicable to the frame was proposed to meet the demand for the detailed design of the daylighting roof, and to build the reconstruction model for detailed design. An algorithm for extracting the axes of a polygon’s curved and twisted components was developed to assist in the geometric description. An intelligent cell extraction method was introduced to address the low efficiency of manual panel segmentation. Different strategies were used to generate and evaluate panel layout plans, based on the Guillotine algorithm. The results show that the proposed inverse modeling approach allows for the acquisition of profile geometry information with a defined sampling interval. Furthermore, the established frame model exhibits an accuracy better than 6 mm, making it suitable for panel deepening design applications. Panel cell partitioning methods could automatically extract information about various panel sizes, reducing manual point selection efforts. The material waste rate of the panel layout plan generated by the Guillotine algorithm could be limited to 15%.

• Load-bearing performance of 3D printed steel fiber concrete circular arch structure under circumferential reinforcement

  XIA Jiahui, JIANG Youbao, ZHANG Mingliang, WEN Jun, SHEN Tong

  2026,48(1):184-193, DOI: 10.11835/j.issn.2096-6717.2023.137

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  In order to enhance the mechanical properties of 3D-printed concrete arc arch structures, this paper uses the methods of adding steel fibre and configuring steel reinforcement to investigate the effect of circumferential reinforcement on the mechanical properties of 3D-printed steel fibre concrete arch structures. The appropriate steel fiber content was determined by mechanical property tests under different steel fiber contents. On this basis, two groups of 3D-printed concrete arc arch structures were designed. By applying a uniform load to the arch roof, the load-displacement curves, strain changes with load, cracking load, and ultimate load of the arch structures were measured, and their deformation and failure laws were analyzed. Considering the influence of symmetric and asymmetric loading, as well as the position of sectional reinforcement, on the arch structure, finite element calculations were carried out to further study its bearing performance. The results show that: (1) When the steel fiber content changes in the range of 0-3%, the compressive strength of 3D-printed concrete in X, Y, and Z directions first increases and then decreases, and the compressive strength in the X, Y, and Z directions corresponding to 2% steel fiber content is the highest; (2) The loading failure process of the two groups of arch structures is basically the same, and the ultimate bearing capacity of the arch structure with circumferential reinforcement is about 37.5% higher than that of the plain concrete arch structure; (3) The adopted finite element modeling method is relatively accurate, with the error between the simulation results and the test results less than 4%. The loading method and the position of section reinforcement have certain effects on the ultimate bearing capacity of the arch structure.

• The impact of damage parameters of rail transit steel spring isolators on dynamic response

  FU Weiqing, DI Huilin, ZHAO Liang, WANG Jian

  2026,48(1):194-201, DOI: 10.11835/j.issn.2096-6717.2023.106

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  In the structural context of urban rail transit systems, spring isolators are susceptible to stiffness reduction, damage, and sagging due to fatigue effects. The presence of concealed components can render their detection challenging during routine inspections. A vehicle-track coupled model was established using the finite element software ABAQUS. The model was validated using actual vibration data from a specific section of the Shenzhen Metro’s floating slab. A uniform design approach was adopted for the execution of parameter experiments on spring isolators under various conditions, including different levels of damage in terms of quantity, severity, and location. Through model simulation, the quantitative impact of these damage parameters on the vibration response of the floating slab was determined. The calculation results indicate that the location of damage to the spring isolators exerts the greatest influence on the acceleration and displacement of the floating slab, with respective impact weights of 50% and 49.3%. The impact of the number of damaged isolators is 28.4% and 27.9%, while the impact of damage severity accounts for 21.6% and 22.8%.It can be seen that the damage location of the floating slab has the greatest influence on its vibration response, followed by the number of damaged steel springs, and finally the damage degree of steel springs.

Environmental Engineering

• The mechanical properties and contaminant migration evolution of solidified oil-contaminated soil under leaching

  LI Min, YU Hemiao, LI Hui, ZHAO Moyan

  2026,48(1):202-209, DOI: 10.11835/j.issn.2096-6717.2023.128

  Abstract: (0) HTML (0) PDF (2.19 MKB)(0)

  Understanding the mechanical properties of solidified oil-contaminated soil and the evolution of contaminant migration and diffusion under environmental effects is a key prerequisite for promoting the reuse of contaminated soil projects. Lime and fly ash with a low-carbon concept were selected as solidification materials. Combined with a leaching test and COMSOL Multiphysics software, the control of the solidification effect on oil migration under leaching environment was evaluated macroscopically by the oil content after leaching, and the mechanical stability under leaching was evaluated by soil strength and deformation. The results indicate that the solidification of lime-fly ash has the potential to address the issue of contaminant migration and diffusion, particularly in cases where a significant number of contaminants are migrating under the leaching effect of contaminated soil, and to achieve effective control of the migration of oil contaminants in soil. The oil content at each interface of solidified contaminated soil under the action of leaching is always close to the initial oil content setting state, and the migration rate is only 1.35%-2.76%. The variation range of the mechanical parameters of the solidified contaminated soil under leaching is positively correlated with confining pressure and contaminant concentration, but only fluctuates within 10 s of the initial stress and then the strength value is stable at 5.77×10⁴-6.07×10⁴ N/m², and the maximum fluctuation value of displacement is 1.73×10^-3-6.46×10^-2 mm. The mechanical stability of solidified contaminated soil is good, and the safety factor F_s is more than 10. Lime-fly ash solidified oil-contaminated soil can take into account both environmental and engineering requirements, and exhibits the potential for engineering reuse.

• Experimental study on solidifying landfilled municipal sludge using ferrous sulfate and cementitious materials

  GUO Xiaojing, HUANG Zhiliang, CHEN Hui, HE Xiao, PU Hefu, YUAN Man, CAO Jianfeng

  2026,48(1):210-220, DOI: 10.11835/j.issn.2096-6717.2023.140

  Abstract: (0) HTML (0) PDF (2.69 MKB)(0)

  In order to address the issues of elevated water content and diminished strength of municipal sludge in the landfills, a synergistic method using ferrous sulfate and cementitious materials (such as lime, fly ash, and cement) was proposed for the in-situ solidification of landfilled sludge, with its reagent dosage further optimized by the response surface method (RSM). In this study, the water content and unconfined compressive strength (UCS) of the solidified sludge after 28 days of curing were selected as evaluation indexes. Initially, a single factor test was conducted to explore the roles of ferrous sulfate and cementitious materials in the sludge solidification process, followed by the analysis of interactions between ferrous sulfate and cementitious materials using RSM to optimize the material dosages. The results showed that both ferrous sulfate and cementitious materials could reduce the water content of the solidified sludge, with lime and cement exhibiting more significant reduction effects; the UCS of the solidified sludge increased with increasing ferrous sulfate and cement dosages, first increased and then decreased with lime dosage, and remained essentially unchanged with fly ash dosage; the quadratic polynomial model derived from RSM could accurately predict the water content and UCS of the solidified sludge, and verification indicated that the relative error between the predicted and experimental values was less than 20%; under the constraints set in this study, the water content of the solidified sludge in the recommended solution R7 (ferrous sulfate 8%, lime 6%, fly ash 10%, and cement 11%) decreased from 360.3% to 131.5%, while the UCS increased from 0 to 317.0 kPa. The aforementioned results met the requirements for landfill disposal and mechanical access.

• Characterization of surface microbial community structure and identification of dominant species on the Dazu Thousand-handed and Thousand-eyed Avalokitesvara

  JIANG Siwei, YANG Hao, HE Qiang, FENG Xuemei, WANG Wei, ZHAO Gang, GUO Jinsong

  2026,48(1):221-230, DOI: 10.11835/j.issn.2096-6717.2025.097

  Abstract: (0) HTML (0) PDF (2.65 MKB)(0)

  The Dazu Thousand-handed and Thousand-eyed Avalokitesvara is regarded as the largest and most completely preserved cliff carving of its kind in China. It is a remarkable integration of rock carving, polychromy, and gold foil application, and is regarded as the largest and most completely preserved Thousand-handed Avalokitesvara cliff carving extant in China. Recent continuous monitoring has revealed evident deterioration of the gold foil surface, primarily manifested as discolouration, cracking, and loss of the foil. A plethora of studies have examined the influence of environmental physicochemical factors and material characteristics on the corrosion of gold foil, however, the influence of microorganisms has received limited attention. The present study was conducted for the purpose of systematic characterisation of the microbial communities colonizing the gold foil surface using sterile swab sampling followed by high-throughput sequencing technology of the 16S rRNA gene and the Internal Transcribed Spacer (ITS). The results showed that bacterial communities were dominated by Firmicutes, Actinobacteriota and Proteobacteria at the phylum level, with Salinisphaera and Pseudonocardia identified as the core dominant genera. Fungal communities were primarily composed of Ascomycota and Mucoromycota, exhibiting dominance of Aspergillus, Filobasidium, and Mucor. Two dominant fungal strains (Aspergillus versicolor and Mucor fragilis) were successfully identified through selective media isolation, combined with colonial morphology observation and ITS sequence analysis. Based on the existing literature on microbial metabolism, these strains are hypothesized to facilitate gold foil corrosion via synergistic physical, chemical, and bioelectrochemical mechanisms.

• Research advances in methane production by river microorganisms

  WU Erhan, MAO Yufeng, HE Qiang, KONG Ciming

  2026,48(1):231-242, DOI: 10.11835/j.issn.2096-6717.2024.113

  Abstract: (0) HTML (0) PDF (877.08 KKB)(0)

  Methane (CH₄), an important greenhouse gas, exerts a substantial influence on global climate change. Rivers are crucial sites for methane production, but the complexity of environmental conditionsin rivers makes it difficult to conduct in-depth research on methane generation by river microorganisms with traditional methods. This article first outlines the basic classification of methanogenic microbes, their distribution and the pathways of methane formation such as the hydrogen nutrition metabolism pathway, the formic acid fermentation pathway, the acetic acid fermentation pathway, the methyl nutrition pathway, and the non-enzymatic reaction pathway. Then, it explores the eight environmental factors affecting the methane production process of river microorganisms: temperature, pH value, redox potential, flow rate and water level, water flow shear force, meteorological conditions, and vegetation type. Subsequently, an overview is provided of the application of molecular biology techniques including PCR technology and high-throughput sequencing, in the study of river microbial methane production. Finally, it points out the problems in current research on methane production by river microorganisms, which are the insufficiency in characterizing river environments, limitations in the application of PCR and sequencing technology, as well as the complexity of data interpretation and analysis. Moreover, it discusses future research on river methane emissions from three directions: the construction and application of river environmental models, the deeper application of molecular biology technology, and knowledge sharing and intelligent analysis, providing new ideas and methods for the exploration on river microbial methane production.

• Classifying rockburst in deep underground mines using a robust hybrid computational model based on gene expression programming and particle swarm optimization

  Quang-Hieu TRAN, Xuan-Nam BUI, Hoang NGUYEN

  DOI: 10.11835/j.issn.2096-6717.2022.023

  Abstract: (410) HTML (0) PDF (2.31 MKB)(581)

  In deep underground mining, rockburst is taken into account as an uncertainty risk with many adverse effects (i.e., human, equipment, tunnel/underground mine face, and extraction periods). Due to its uncertainty characteristics, accurate prediction and classification of rockburst tendency are challenging, and previous results are poor. Therefore, this study proposed a robust hybrid computational model based on gene expression programming (GEP) and particle swarm optimization (PSO), called GEP-PSO, to predict and classify rockburst tendency in deep openings with an accuracy improved. A different number of genes (from 1 to 4) and linking functions (e.g., addition, extraction, multiplication, and division) in the GEP model were also evaluated during the development of the GEP-PSO model aim. Geotechnical and constructive factors of 246 rockburst events were collected and used to develop the GEP-PSO models in terms of rockburst classification. Subsequently, a robust technique to handle missing values of the dataset was applied to improve the dataset""s attributes. The last step in the data processing stage is the feature selection to select potential input parameters using a correlation matrix. Finally, 13 hybrid GEP-PSO models were developed with different accuracies reported. The findings indicated that the GEP-PSO model with three genes in the structure of GEP and the multiplication linking function provided the highest accuracy (i.e., 80.49%). The obtained results of the best GEP-PSO model were then compared with a variety of previous models developed by previous researchers based on the same dataset. The comparison results also showed that the selected GEP-PSO model results outperform those of previous models. In other words, the accuracy of the proposed GEP-PSO model was improved significantly in terms of prediction and classification of rockburst grade. It can be considered widely applied in deep openings aiming to predict and evaluate the rockburst susceptibility accurately.

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• Study of statistical damage constitutive model for rock considering pore ice

  Long Haiping, Zhang Haoyang, Min Qinghua, Jiang Annan, Zheng Fu

  Abstract: (28) HTML (0) PDF (0.00 ByteKB) (0)

  Artificial freezing method has become a key construction technology for underground space engineering to cross the water-rich rock layer, and the mechanical properties of the frozen wall need to be studied by comprehensively considering the effects of its internal pore ice content and freezing temperature. In this paper, the mechanical parameters of pore ice and rock are equated by applying the mixing law theory of meso-mechanics, and the Weibull distribution is used to describe the probability of micro-elementary damage, and the damage constitutive model of rock considering pore ice is established. The validation results of triaxial compression tests show that the model parameter equivalization improves the fitting accuracy of the stress-strain curve for the whole process of freezing sandstone significantly, which is about 7.22% higher than that of the conventional model. The results of the evolution analysis of the characteristic parameters m and F confirm the enhancement effect of pore ice on the homogenization and average strength of the rock mass. In addition, the physical significance of the model parameter system is clear, with a view to providing theoretical references for the study of rock mechanical properties and the design and construction of artificial freezing engineering under low-temperature environment.

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• 循环荷载作用下饱和土石混合料侧限变形试验研究

  HE Feng, XU Yong-qing, HU Sheng-liang, LI Hai-chao, TONG Chen-xi

  Abstract: (47) HTML (0) PDF (0.00 ByteKB) (0)

  Soil and rock mixtures are commonly used as subgrade fill materials for mountain airports. When subjected to cyclic loading, they experience cumulative deformation, leading to uneven settlements that can compromise the stability of the upper foundation. To understand this deformation pattern, a series of dynamic compression tests was conducted on soil and rock mixtures. The study analyzed how the specimen's cumulative deformation changed with the number of cyclic loads across different stone contents and confining pressures, and it developed a corresponding mathematical model. Results showed that, at a fixed stone content, higher confining pressure resulted in greater maximum axial cumulative deformation, with the rate of increase accelerating as stone content increased. The deformation curve typically has two phases: an initial rapid accumulation of axial deformation during cyclic loading, followed by a slower growth as the specimen densifies. Based on these findings, a simple model describing the law of cumulative deformation was proposed, which aligned well with experimental data. The study also examined how excess pore water pressure in saturated specimens evolves during cyclic loading, noting its rapid buildup and slow dissipation, providing valuable insights for managing differential settlement and assessing the stability of mountain airport subgrades.

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• Study on the Flexural Performance of Cement-Based Plant Fiber Prefabricated Composite Long Slab

  zhangwangxi, huanghe, zhangchen, xieixiangrong, yuanchao, yiweijian

  Abstract: (23) HTML (0) PDF (0.00 ByteKB) (0)

  To study the flexural performance of 5.1-meter-long cement-based plant fiber fireproof and thermal insulation prefabricated composite slabs, this paper conducted four-point bending tests on four full-length composite slabs, analyzed their failure characteristics, crack characteristics, strain laws, ultimate bearing capacity and ductile coefficient, and discussed the influence of different protective layer thicknesses under positive and negative bending moment loading. The results show that the specimens with positive and negative bending moments present different failure characteristics. The prominent manifestation is that the prefabricated bottom plate of the specimens with positive bending moments shows no obvious phenomenon before failure and presents brittle failure characteristics. At this time, the load will have a certain amplitude of "steep drop", and eventually the crushing phenomenon occurs in the compression zones of both. This composite long plate is lightweight, has good bearing capacity and good ductility. Among them, the positive bending moment specimen has a higher ultimate bearing capacity than the negative bending moment specimen by approximately 50% due to the high tensile strength of the prefabricated bottom plate in the tensile zone and about 23% higher than the cast-in-place slab with the same cross-section. The negative bending moment specimen has a lower bearing capacity than the cast-in-place slab due to the lower compressive strength of the plant fiber cement-based material in the compression zone. The prefabricated base plate placed in the tensile zone can significantly inhibit crack propagation. The crack spacing of the specimens with positive bending moment is 20% to 30% smaller than that of the specimens with negative bending moment. Finally, based on the assumption of the flat section and by using the existing specification formulas, the loading mode coefficient was introduced and a correction formula for the cracking bending moment was proposed. The error between the theoretical calculation value and the test value is less than 5%. The research shows that this correction formula can provide a reliable basis for the calculation of the cracking bending moment of this new type of composite slab.

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• Study on Fragility Functions of H-Shaped Steel Columns

  ZHENG Shansuo, ZHAO Wang, YANG Song, LI Yongming, LIU Liguo

  Abstract: (22) HTML (0) PDF (0.00 ByteKB) (0)

  H-shaped steel columns are critical components in steel frame structures, necessitating performance-based seismic assessment. Fragility functions—cumulative distribution functions reflecting the probability of engineering demand parameters (EDP) exceeding damage thresholds—are pivotal but lack codified frameworks compliant with Chinese standards. This study integrates 94 global low-cycle reversed loading test datasets for H-shaped steel columns, adopting drift ratio as the EDP. Three damage states are classified based on structural degradation patterns, with tailored repair strategies. Fragility functions conforming to lognormal distribution are established using the FEMA P-58 methodology. The effects of axial compression ratio and cross-section classification are analyzed. Key findings: Elevated damage states significantly increase fragility function medians; Higher axial compression ratios accelerate plastic hinge formation and strength degradation, reducing medians; Reduced cross-section width-to-thickness ratios delay local buckling, enhancing medians; Cross-section classification outweighs axial compression ratio in influencing fragility curves. The proposed framework aligns with Chinese codes, addressing a research gap and supporting seismic resilience evaluation of steel structures.

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• Study on the concave bounding radius and surface amplification coefficient of the scattering stability influence field of semicircular terrain under strong ground motion in hard field

  Chen shanzheng, yuan xiaoming

  Abstract: (34) HTML (0) PDF (0.00 ByteKB) (0)

  The analytical solution has unique advantages in understanding the influence of terrain conditions on ground motion, but the previous research is basically limited to a single frequency steady-state response and frequency domain solution. In this paper, the probability of exceeding the surface magnification coefficient of the semicircular terrain in the hard field is studied by using the analytical method and the time domain analysis of a large number of measured strong earthquake records, and the distribution law of the concave boundary radius and the surface amplification coefficient is proposed. The wave function expansion method is used to derive the analytical solution of the peak acceleration amplification coefficient of the surface of the plane wave scattering field in the semicircular terrain. 100 strong earthquake records were extracted from the important strong earthquake network at home and abroad to form the input ground motion. According to the specification, a typical hard field is taken, and the excess probability of the surface amplification coefficient of the semicircular terrain is calculated by time-frequency transformation. The results show that the boundary radius of the concave body exists, that is, for any semi-circular sag terrain that exceeds the boundary radius, the surface acceleration amplification coefficient will achieve a stable convergence and consistent result in the engineering sense. The boundary radius of the semicircular terrain on the hard field is proportional to the shear wave velocity of the site. For depressions exceeding the boundary radius, the surface acceleration amplification factor varies from 0.3 to 2.0 depending on the angle of the incident wave and different observation points. In this paper, the distribution law of the concave boundary radius and its surface amplification coefficient is given for the first time, which can make up for the lack of understanding of the influence of local topography on ground motion.

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• Optimization of Room Air Conditioners for Uniform Thermal Environments

  QIU Xiangwei, ZHAI Yingxian, LIU Zhilong, LI Ziqiao, LIU Meng

  Abstract: (24) HTML (0) PDF (0.00 ByteKB) (0)

  With increasing public demand for indoor environmental quality and the frequent occurrence of extreme high-temperature weather, air conditioning has become an essential means for elderly Chinese individuals to maintain a comfortable thermal environment. However, traditional air supply designs or improper placement of air conditioners can lead to uneven temperature distribution, characterized by "cooler near the unit and warmer farther away." To alleviate discomfort, the elderly often increase fan speed or lower the temperature, resulting in energy waste and health risks. To address this issue, this study proposes a dual-layer near-far circulating air supply method based on ultra-low Mach number counter-rotating fans and annular rotating jet technology. Tests in a controlled climate chamber and home scenario evaluations with 20 elderly participants demonstrated that this technology maintains a longitudinal temperature difference within 0.7°C in a 40 m2 room (0.1–1.7 m range), with a near-end (within 2.0 m) temperature difference below 1.0°C. The elderly felt cooler within 10 minutes and achieved thermal comfort in all areas after 60 minutes, with minimal draft sensation. This technology effectively improves indoor temperature uniformity and thermal comfort, providing technical support for future intelligent air conditioning systems designed for elderly care.

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• A new method for the restoration of bone and antler relics by microbial induced hydroxyapatite precipitation

  GU Laiyuan, Yang Yang, LI Xiaolong, YE Lin, ZHANG Cheng, LIU Yuanjian, LIU Hanlong

  Abstract: (46) HTML (0) PDF (0.00 ByteKB) (0)

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• Study on the Effect of Environmental Humidity on the Self - Healing Performance of Damaged UHPC

  LI Yue, DONG Chao, DING JingXiang, LUO AnRan, NING Zhe

  Abstract: (69) HTML (0) PDF (0.00 ByteKB) (0)

  In order to obtain the influence law of environmental humidity on the self - healing performance of damaged ultra - high - performance concrete (UHPC), pre - cracks were induced in the specimens by loading, and then the specimens were subjected to secondary curing in four different environments: continuous immersion, wet - dry cycling, natural curing, and air - tight isolation. Subsequently, compressive and flexural tests as well as ultrasonic testing were conducted. The self - healing effects of UHPC were evaluated in terms of appearance characteristics, mechanical properties, density, and micro - morphology. The results show that environmental humidity has a significant impact on the self - healing performance of the specimens, the difference of self-healing rate under different humidity environments is due to the migration and transportation of water. In water - deficient environments (air - tight isolation and natural curing), no obvious healing products were observed at the cracks of the specimens, and the recovery rates of strength and density of the specimens were low. In water - saturated environments (wet - dry cycling and continuous immersion), the specimens had abundant visible healing products at the cracks, which were composed of calcium hydroxide (Ca(OH)2) and calcium silicate hydrate (C-S-H) gel and could effectively repair the cracks. The recovery rates of strength and density of the specimens were better in these environments. The recovery rates of strength and density of the specimens increased with the increase of the damage degree of the specimens. In the continuous immersion environment, compared with the specimens with a damage degree of 70%, the specimens with a damage degree of 90% had an increase of 16.59% in compressive strength recovery rate, an increase of 11.19% in flexural strength recovery rate, and a maximum increase of 64.43% in density recovery rate.

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• Frequency dispersion characteristics and high-frequency guided wave propagation analysis of honeycomb sandwich panels

  Yanshi, Chenxiukun, Wangxuenan, Mengqingyi

  Abstract: (46) HTML (0) PDF (0.00 ByteKB) (0)

  For solving issues of the wave performance applicability of the deformation-based equivalent model for Honeycomb Sandwich Panels (HSPs) and difficulty in sensing signal feature extraction for debonded delamination identification, an equivalent conversion method is used by changing an HSP structure into a three-layered periodic structure, and the Comsol Multiphysics software is applied to calculate and draw frequency dispersion curves. The guided wave performance applicability is investigated by comparing two kinds of finite element (FE) analysis results from the equivalent and actual two models of the HSP structure. The FE method is applied to explore the feature of guided wave deboned-induced-split-flow. The model tests are used to validate the correctness of the frequency dispersion performance and the deboned-induced-split-flow feature of high-frequency guided waves. The results show that the wave performance differences between the equivalent conversion and actual models are obvious as the wavelength of guided wave is not greater than a single cell height in the HSP, the debonded delamination is the main reason for deboned-induced-split-flowing, and it is recommended that the time-domain sensing signals of high-frequency activated A0 mode guided waves are used as extracted features for the debonded delamination identification of HSP structures.

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• Study on model tests and mechanical mechanism study of drainage rigid pile in coral sand foundation under horizontal cyclic loading

  HUANG Li, WANG Buxin, YANG Xin, ZOU Tan, CHEN Zhixiong

  Abstract: (59) HTML (0) PDF (0.00 ByteKB) (0)

  To address the critical issue of pile foundations in coral sand foundations subjected to wave-induced cyclic loading during island and reef construction, this study investigates the pile-soil interaction mechanisms of drained rigid piles under static and cyclic horizontal loading through model tests. Firstly, static loading tests determined the ultimate bearing capacity of the drained rigid pile to be 376 N. It was found that the peak bending moment occurred at a depth of 2 to 2.8 times the equivalent pile diameter below the foundation surface, and the slope of the p-y curves flattened with increasing embedment depth. Furthermore, a comparative study on the dynamic response of drained rigid piles and conventional rigid piles under horizontal cyclic loading revealed that: The pile head displacement and extreme bending moment values of conventional rigid piles were greater than those of drained rigid piles. The peak bending moments for both pile types occurred at depths of 3 to 4 times the equivalent pile diameter below the foundation surface. The slopes of the p-y curve hysteresis loops for both conventional and drained rigid piles increased with greater soil depth. However, the drained rigid piles exhibited smaller attenuation amplitudes in both soil resistance and dynamic stiffness compared to conventional rigid piles, while simultaneously demonstrating greater maximum soil resistance and dynamic stiffness. The research demonstrates that drained rigid piles significantly enhance the bearing stability of coral sand foundations under cyclic loading, offering valuable insights for the design of pile foundations in island and reef engineering projects.

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• Study on seismic random response of nuclear power plant considering structural parameter uncertainty based on cubature formula

  Qin Miaojun, Wang Xiaobin, Zhou Cheng, Zhao Yangang

  Abstract: (60) HTML (0) PDF (0.00 ByteKB) (0)

  The safety of nuclear power plants (NPPs) under earthquake is of great significance to the development of nuclear energy. In order to study the influence of structural parameter uncertainty on random seismic response of NPP, a random response analysis method considering structural parameter uncertainty is proposed based on cubature formula; using the random vibration theory, the expression of response power spectrum considering structural parameters is derived. And this proposed method is verified by a single degree of freedom model. The results show that considering the uncertainty of structural parameters has a great impact on the response power spectrum. the power spectrum value of structural response is more dispersed in the frequency range due to the randomness of its parameters. The root means square of response obtained by cubature formula is closer to the results of Monte Carlo simulation (MCS) and is larger than the results without considering the parameter uncertainty. The finite element model of an NPP is established, and the random seismic response considering the uncertain material parameters of the NPP structure is calculated based on the cubature formula. The results show that the maximum response of the structure will be underestimated and the reliability of the structure will be overestimated without considering the uncertainty of structural parameters. Therefore, this method can be used to consider the uncertainty of parameter of important structures in practical engineering.

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• Pseudo-Dynamic Analysis of Seismic Active Earth Pressure of Finite Soils

  XIA Qiong, Feng Xiaohui, Liu Deren

  Abstract: (43) HTML (0) PDF (0.00 ByteKB) (0)

  Earth pressure of finite soil will arise when the backfill width behind retaining structure is limited. Seismic active earth pressure is the primary load for retaining wall design in earthquake areas. Existing seismic earth pressure calculation theory which is suitable for semi-infinite fill does not apply to calculating seismic earth pressure of finite backfill. Seismic inertia force is caculated with pseudo-dynamic method, and differential equations for seismic active earth pressure of finite backfill are established with horizontal differential element method considering soil arching effect.Comparisons and analysis of the analytical results and experiment results are performed as well as other theoretical solutions, and the rationality of the proposed method is verified. By analyzing the main parameters, the distribution rules of seismic active earth pressure of finite backfill are revealed. The results show that the most disadvantage combination of seismic inertia force direction is that Q_v is vertical downward and Q_h is horizontal towards the retaining wall. The parameter analysis discusses the effects of horizontal seismic coefficient, finite backfill width, fill cohesion, internal friction angle and wall-soil friction angle on the seismic active earth pressure coefficient and distribution. The proposed calculation method can

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• Study on Shear Strength Influencing Factors of Transparent Soft Rock

  Zeng Youheng, XIONG Peixi, Fang Xiangwei, QIAO Longjiang, TANG Guangchun, HUANG Sheng

  Abstract: (45) HTML (0) PDF (0.00 ByteKB) (0)

  Transparent soft rock exhibits significant application value in geotechnical engineering model tests, yet systematic studies on the factors and mechanisms influencing its shear strength remain limited. In this study,fused quartz sand, nano-scale hydrophobic silica powder, No. 15 white oil, and n-dodecane were selected as primary transparent cementing materials to investigate the effects of silica powder content, quartz sand particle size, and sample dry density on the shear strength of transparent soft rock. Theoretical values of cohesion and internal friction angle for the Chongqing Jigongzui Tunnel model test were determined using dimensional analysis. Orthogonal experiments were conducted to optimize the material ratio and further analyze these influencing factors.Results demonstrate that, Increased silica powder content leads to an approximately linear enhancement in cohesion, while the internal friction angle remains nearly unaffected.Higher proportions of fine particles result in an initial decrease followed by an increase in internal friction angle, with negligible impact on cohesion.Elevated dry density induces a rapid-to-gradual ascending trend in cohesion, while the internal friction angle exhibits initial stability followed by a progressive increase.The optimized ratio (4% silica powder, particle size group D with 75% 0.5-1 mm particles, and dry density of 1.35 g/cm3) shows high compatibility with the surrounding rock parameters of the Chongqing Jigongzui Tunnel. This research provides theoretical and technical foundations for applying transparent soft rock in geotechnical model testing..

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• Keywords: Temperature Prediction in Box Girders; Genetic Algorithm (GA); CNN-BiLSTM-Attention; Meteorological characteristics; Model evaluation; Hyperparameter Optimization

  WANG YU CHEN, ZHANG FANG, YUAN JUNJIE, LIN SHICHEN, CONG LONGYU

  Abstract: (76) HTML (0) PDF (0.00 ByteKB) (0)

  Concrete box-girder bridges subjected to non-uniform temperature fields are prone to thermal stress-induced cracks and deformation, which seriously threaten structural safety and durability. Accurate prediction of the temperature field serves as the critical foundation for real-time monitoring, damage early warning, and preventive mitigation strategies. To address the insufficient accuracy of discrete-point temperature predictions under multi-factor meteorological features, this study proposes a GA-optimized CNN-BiLSTM-Attention temporal model. The model integrated Bidirectional Long Short-Term Memory (BiLSTM) networks to capture bidirectional temporal dependencies in time-series data, and integrated Convolutional Neural Networks (CNN) to extract localized spatial features from time-series data, while further incorporating a self-attention mechanisms to dynamically assign weights to meteorological parameters, thereby enhancing sensitivity to critical features driving temperature variations. Concurrently, GA is employed to optimizes hyperparameters ( the number of hidden units, learning rate, etc.) to improve prediction stability and generalization capability. Validation results based on field monitoring data from Nanchong Jialing River Bridge demonstrated that the model's superior performance in both short-term (S1 segment) and long-term (S2 segment) predictions, achieving RMSE values as low as 0.178 and 0.129 respectively, with the coefficient of determination (R2) approaching 0.99. Compared to baseline models (e.g.,LSTM, BiLSTM), the error reduction exceeds 20%, while its capability to capture temperature peaks exhibited substantial enhancement. This research validated that the hybrid model integrating spatiotemporal feature fusion and dynamic weight allocation effectively could resolve complex meteorological coupling mechanisms, while providing a high-precision temperature field prediction tool for bridge structural health monitoring. This advancement possessed significant engineering implications for enhancing infrastructure service life and advancing safety-oriented operation and maintenance practices.

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• Study on Contaminant Transport Mechanisms in Clay Liners under Varying Saturation Conditions

  Hou Shiwei, SHAN Xinyuan, Meng Suyun, Du Xiuli

  Abstract: (42) HTML (0) PDF (0.00 ByteKB) (0)

  As a critical factor governing pollutant migration rates, soil saturation directly influences the long-term impermeability and contaminant retention efficacy of clay liners in landfills. To elucidate the impact of saturation-dependent mechanisms of pollutant transport in practical clay liners, a dynamic coupled model for contaminant migration in unsaturated soils was developed in this study. Based on mass and energy conservation principles, the generalized Darcy’s law was integrated into the framework, while dynamic variations in soil transport properties and physical characteristics were rigorously accounted. The governing equations for unsaturated soil consolidation, pore water flow, heat transfer, and contaminant transport were systematically formulated to establish the multi-physics model. Numerical simulations of the constructed model were conducted using the finite element analysis platform COMSOL Multiphysics, with case studies implemented to validate the model's rationality in civil engineering scenarios. Further analysis was conducted on the temporal evolution patterns of pore fluid pressure, contaminant concentration, and soil settlement under variations in saturation. Results demonstrate that pore fluid pressure transitions from shallow negative pressure to global negative pressure during consolidation, with 1–4 kPa higher pressure values being observed under high-saturation conditions (Sr > 0.85) compared to medium-low saturation cases; Solute migration rates were found to increase by 10%–25% with elevated saturation, exhibiting nonlinear attenuation with depth; Soil settlement, characterized by a nonlinear trend, peaked at approximately one year, where 5%–10% greater maximum settlement was recorded in high-saturation scenarios (Sr > 0.85) than in low-saturation cases.

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• A modified method predicting the trajectory and holding capacity of drag anchors in sand

  LI Da, LI Shuzhao, SUN Guodong, SONG Yonghao, WANG Dong

  Abstract: (55) HTML (0) PDF (0.00 ByteKB) (0)

  Drag anchors have the high anchor efficiency and low manufacturing cost, and are widely used for the mooring of offshore floating platforms. However, there are often non-negligible errors in the prediction of the anchor penetration and holding capacity when the drag anchor is installed in sand. A modified method was developed to predict the installation process of the drag anchor, which divides the whole installation process into several incremental steps and allows the bottom surface of the fluke to separate from sand. At each incremental step, the limit equilibrium equations of the anchor and soil in failure are established to obtain the holding capacity, and the increment of the horizontal displacement, burial depth and rotation were calculated, based on the principle of minimum force to drag the anchor, with a reasonable direction specified for the drag anchor motion. Small-scale model tests were conducted on drag anchors with two types of the shank length, and the relative density of the sand sample was 47%. The holding capacity and position of the anchor were measured in real time. During the tests, it was observed that the bottom surface of the fluke already separated from the sand sample in the early stage of installation, and the burial depth of the anchor still increased with the increment of the holding capacity, which proved the rationality of the assumption of separation in the modified method. The rationality of the modified method was verified by comparing the measured values and predicted values of the anchor trajectory and holding capacity. Both the test results and calculation results indicate that, when the shank length increases from 30 cm to 36 cm, although the penetration depth of the anchor padeye and the rotation of the anchor body decrease, the final holding capacity still increases by 18%.

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• Experimental investigation on axial compression behavior for prefabricated reinforced UHPC tube infilled with seasand seawater concrete

  jiachenhao, liying, wanglihui, wangyaohong

  Abstract: (43) HTML (0) PDF (0.00 ByteKB) (0)

  The utilization of sea sand to produce seawater sea sand concrete (SSC) can address the shortage of river sand resources in construction projects.Seasand Seawater Concrete (SSC) demonstrates significant advantages in addressing the shortage of river sand resources in engineering construction. However, it faces critical challenges such as high chloride ion content and corrosion-susceptible steel reinforcement. Ultra-High Performance Concrete (UHPC), known for its exceptional high strength, impermeability, and durability, faces limitations in widespread application due to prohibitively high material costs. This study proposes a novel ?precast steel-reinforced UHPC tube encased SSC composite column (RUHPC-SSC composite column) by leveraging the physical-mechanical properties and complementary advantages of SSC and UHPC. Spirally confined UHPC tubular shell acts as a permanent structural formwork for casting the SSC core, providing both confinement and corrosion resistance. Axial compression static tests were performed on 12 composite short columns, and the influence of volumetric spiral reinforcement ratio and diameter-to-thickness ratio parameters on the axial compressive performance was systematically investigated. The experimental results suggest that the failure mode of the RUHPC-SSC composite column is oblique shear compression failure, with the UHPC tube maintaining structural integrity post-failure. The peak bearing capacity of the RUHPC-SSC composite column exhibits a negative correlation with the spacing of spiral stirrups in the UHPC tube and a positive correlation with the diameter-to-thickness ratio. Compared to monolithic RSSC columns, the RUHPC-SSC composite column achieves a 139.8% increase in peak bearing capacity. The UHPC tube-spiral stirrup synergy boosts both strength and deformability of the composite column.

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• Study on the correlation between physical environment parameters and passenger satisfaction in the waiting room of high-speed railway station in summer

  DONG WENJING

  Abstract: (68) HTML (0) PDF (0.00 ByteKB) (0)

  The waiting hall's environmental quality directly impacts passengers' travel experience. The high temperatures in summer impose higher requirements on the physical environmental parameters of high-speed rail station waiting halls. By investigating and monitoring the indoor physical environment of waiting halls in different regions of China during summer, this study analyzes passenger satisfaction survey data from corresponding stations to explore the relationship between the physical environment quality of these waiting halls and passenger satisfaction. Through systematic field measurements, key physical environment parameters such as temperature, humidity, noise, illumination, PM10 levels, and carbon dioxide concentration were collected in detail from 11 high-speed railway stations. The indoor physical environment status of different station waiting rooms during summer was compared and analyzed while collecting passenger satisfaction feedback through questionnaire surveys. Based on environmental monitoring data and questionnaire results, an analysis is conducted to determine the quantitative relationship between overall satisfaction with the physical environment (including thermal environment, light environment, sound environment, and air quality) in high-speed railway station waiting halls during summer using factor analysis and multiple linear regression methods. The results indicate that during the summer season, passenger satisfaction is primarily influenced by temperature, followed by air quality and sound environment. The impact of light environment on overall satisfaction is found to be relatively minimal. In terms of the thermal environment, there is a strong correlation between humidity and ventilation with overall satisfaction regarding the physical environment. This is followed by the uniformity of temperature distribution and actual temperature. In the acoustic environment, noise factor and broadcast clarity exhibit a significant correlation. The illuminance in the light environment is more important, while air pollutants and air quality freshness account for a relatively substantial proportion.

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• Study on the influence of different damage-controllable construction methodson mechanical performance of masonry-infilled RC frames

  CHI BIN, DONG ZHIXIANG, QUAN YUHU, YANG XU, WANG SHIYU

  Abstract: (46) HTML (0) PDF (0.00 ByteKB) (0)

  To evaluate the applicability of commonly used damage-controllable construction methods for masonry-infilled reinforced concrete (RC) frames, a comprehensive pseudo-static test database comprising 63 specimens in 17 groups of masonry-infilled RC frames was established, including bare frames, rigid connections, and damage-controllable specimens. The discussion on the influence of these construction methods on the mechanical performance of the specimens was systematically analyzed in terms of initial stiffness, maximum load-bearing capacity, displacement ductility, and wall damage patterns. The results indicate that current damage-controllable construction methods are primarily concentrated in two areas: the wall-frame interface and the internal structure of the wall. The design of the wall-frame interface aims to weaken the wall-frame interaction, while the design of the internal structure of the wall seeks to achieve zoning damage control within the wall, thereby improving failure modes. These damage-controllable construction methods can effectively mitigate the excessive initial stiffness and reduce ductility of the specimens observed in traditional rigid connections, albeit at the cost of some load-bearing reserve. Furthermore, compared to the wall-frame interface construction methods, the internal construction methods of the wall show more significant improvements in the displacement ductility, the post-peak mechanical performance, and damaged area ratio of the specimens, rendering it a preferred choice for enhancing the resilience of the wall.

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• Seismic behavior of partially encased composite (PEC) columns with T-shaped sections

  Zhao Bida, Shen Tianchi, Zhu Xiong, Guan Yunjie

  Abstract: (61) HTML (0) PDF (0.00 ByteKB) (0)

  To study the seismic performance of partially encased composite columns with T-shaped sections (abbreviated as T- PEC columns), five T-PEC column specimens with different axial compression ratios and different construction of main steel components (MSCs) are tested subjected to the cyclic horizontal load. The five specimens included two specimens with MSCs of solid-web steel (abbreviated as SWS T-PEC column), and three specimens with MSCs of honeycomb steel (abbreviated as HS T-PEC columns). Combined with test and finite element (FE) analysis results, the impact of steel web opening and the axial compression ratio on the seismic behavior of T-PEC columns are investigated. The results indicate that all T-PEC column specimens failed near the column base, characterized by elastic-plastic buckling of the steel flange and adjacent concrete crushing, showing typical cross-section compression-bending failure mode. The load-displacement hysteresis curves of all column specimens were full, with the hysteresis loops at the same loading level almost coinciding, indicating good energy dissipation and load-bearing stability. SWS T-PEC column exhibited better deformability, ductility, and energy dissipation capacity compared to the HS T-PEC column under the same axial compression. Furthermore, the size of the web opening will affects the PEC column performance, while the shape and spacing of the web opening have little effect on the performance. As the axial compression ratio increased, the lateral stiffness and lateral resistance capacity of the PEC columns increased, but the deformability, ductility, and energy dissipation capacity decreased. Both full-section plasticity method and numerical integration method provided reasonably accurate estimate on the flexural capacity of the section of the T-PEC columns under the action of compression-bending load.

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• Analysis of Compressive Permeability Characteristics of dredged mud under Sorting Effect

  lv tongwei, zhang yong, weng Jiaxing, zeng lingling

  Abstract: (51) HTML (0) PDF (0.00 ByteKB) (0)

  Sorting effect is common in the process of blowing and deposition of dredged mud, which inevitably leads to differences in the distribution of mechanical properties of dredged mud. For the sandy dredged mud, the indoor sedimentation column modeling test was used for sedimentary sorting to form the sorted soil samples in different states, and the compression and permeability properties of the soil body were investigated through the one-dimensional consolidation-permeability test. The results show that the compression and permeability of the soil samples change significantly after sorting, and the compression of the bottom soil sample is obviously smaller than that of the top soil sample; and the permeability coefficient of the bottom soil sample is obviously larger than that of the top soil sample. It was also found that the difference in permeability coefficients after sorting action was related to the pore ratio as well as the fines content, and for soil samples with fines content FC>30 %, a clear quantitative relationship was presented between the pore ratio and the pore ratio at the liquid limit; while for soil samples with fines content FC≤30 % a prediction formula for the permeability coefficient was given.

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• Model test and modified continuous hidden Markov model-based safety evaluation of high arch dam

  Shen Chen, Shaowei Hu, Jinghao Li, Liwen Zheng

  Abstract: (83) HTML (0) PDF (0.00 ByteKB) (0)

  The safety assessment is of great significance for ensuring long-term safe operation of high arch dams. The machine learning algorithm of Continuous Hidden Markov Model (CHMM) has strong capabilities in processing multi-sourced time sequential continuous data, establishing relationship between complex data, and real-time accurate evaluation. Therefore, it has great applicable potential in high arch dam safety evaluation. However, the whole-process safety evaluation of overloading failure of high arch dams via CHMM-based multivariate indices analysis has not been carried out yet. Therefore, this paper carried out an overloading test on a physical model of a high arch dam, monitored the time series of cracks and deformations throughout the dam's failure process, and constructed a high-quality CHMM dataset with low noise and stability. Subsequently, CHMM was applied to the safety assessment of high arch dams, and a new rule for state transfer matrix ordering was proposed to give meaning to the state labels, which improved the readability of the results of CHMM. Finally, the whole-process safety variation of arch dam model was evaluated by the CHMM optimized state sequence, and validated with observed results. The results indicated that CHMM-based state sequence classified the safety status of tested high arch dam into seven levels, which coincide with the time-sequential evolution of deformation and crack, and further proposed the featuring overloading safety. The failure process of tested high arch dam was categorized into quasi-linear, nonlinear of large deformation, arching effect action and complete failure stages with respective overloading safety degrees of 2, 6, 10 and 14. This study provides the new insight into safety evaluation of high arch dam and makes reference for early-warning of high arch dam.

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• A dynamic control method for shield tunneling parameter thresholds based on decoupling analysis of boreability

  wang jian jun, li tong, rong xue ning, wang jia jun, liu peng

  Abstract: (52) HTML (0) PDF (0.00 ByteKB) (0)

  In order to reduce the health risk of equipment due to excessive cutterhead torque fluctuation, the overload and fluctuation of cutterhead torque need to be dynamically suppressed. The dynamic control thresholds of tunneling parameters under the constraint of tunneling efficiency control law is explicitly derived to reveal the suppression strategy on the basis of decoupling the network influence mechanism among geological parameters, tunneling parameters and rock mass boreability through the combinational two-factor analysis. The results show that: the combinational two-factor analysis can learn the low-dimensional characteristics of the mechanism of differential interaction within the rock mass boreability control factors, the multigroup monotonicity analysis and the elliptic conic envelope model can explain the influence mechanism of the factors on boreability. The elliptic conic envelope model can accurately determine the overload risk of cutterhead torque in the form of analytical model in multiple stratum. In the risk management and control task against the tunneling parameters fluctuation and the key components damage of shield, the dynamic control method for shield tunneling parameter thresholds based on decoupling analysis of boreability can provide explicit decision instructions and the control chain of fast command response. The output of the instruction layer of the control method is interpretable for the two-dimensional projection of the elliptic conic envelope equation can be transformed into a dynamic threshold model of tunneling speed with the cutterhead torque thresholds as the control goal under the constraint of tunneling efficiency control law. The command logic of the application layer is prior-determined single factor control, which can not only respond to dynamic instructions quickly, but also enhance the steady state of tunneling parameters.

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• Freeze-thaw durability of sulfate saline soil stabilized with SH agent

  weili, liuqingya, changxinxin, chaishouxi

  Abstract: (98) HTML (0) PDF (0.00 ByteKB) (0)

  Winter freezing and spring thawing cause engineering geological issues such as frost heave cracking, thaw settlement, and boiling subsidence in sulfate saline soil embankment construction. To this end, freeze-thaw test, unconfined compressive strength test, SEM test and CT test were completed on sulfuric saline soil stabilized with lime, SH agent, and fiber to study the mechanical properties degradation and the microstructure damage characteristics under freeze-thaw conditions, clarifying the influence mechanism of the SH agent and fiber on the freeze-thaw durability of the soil. The results show that the UCS of soil exhibited a stage-wise change, with a large decrease, small decrease and stable strength as the number of freeze-thaw cycles increased. With the increase of freeze-thaw cycles, the area ratio and the equivalent diameter of soil particles decreased, some aggregates were broken, and the morphology of soil particles gradually transitioned from elongated to circular. Fiber reinforcement reduces the porosity of soil, and the number of small pores gradually reduced, and the number of medium pores and large pores increased little by little. The number of cracks increases, and they gradually extend from the surface of the specimen into the interior. Sulfate saline soil stabilized with 12% lime, 3% SH agent and 0.3% fiber is a more suitable mix ratio. SH agent wraps soil particles and fills soil pores, as well as the interface interaction between fibers and soil and the spatial network structure formed by fibers, which improves the mechanical properties and freeze-thaw resistance of sulfate saline soil.

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• Experimental study on the ground disturbance characteristics during shield tunneling in high cobble content strata

  SONG Weitao, ZHANG Pei, DU Xiuli, LIN Qingtao

  Abstract: (54) HTML (0) PDF (0.00 ByteKB) (0)

  Compared with ground with low cobble content, a high cobble content strata has characteristics such as large particle pores and point-to-point contact between particles, etc. During shield tunnelling, the large-grained skeleton structure in such strata is more prone to damage, leading to an unstable state. Based on a typical shield tunnel project, a model shield machine that can achieve functions such as cutterhead rotation and spiral discharging soil is used to conduct model test. Shield model tests all were achieved for both shallow tunnel (1.0 D) and deep tunnel (2.0 D) in high cobble content strata (rock content of 70%). Then, from the aspects of shield tunneling mechanical parameters, ground surface settlement curves and excavation face stability, the ground disturbance characteristics of shield tunnelling in high cobble content strata are analyzed. Test results show that for the high cobble content strata, under the same shield advancement parameters, the screw excavator torque shows little difference between shallow and deep tunnels. However, the stable value of cutterhead torque in shallow tunnel is less than that in deep tunnel. Under these two ground conditions, the ground surface settlement curves all show an asymmetric distribution about the tunnel centerline, and the eccentric position is related to the rotation direction of the cutterhead. When the cutterhead rotates clockwise, the symmetry axis of the settlement curve is located on the left side of the advancing direction. The failure modes of excavation face in both shallow and deep tunnels all present to be global instability, with collapse zones encompassing soil both ahead of and behind the cutterhead. Besides, the ground collapse morphologies induced by discharging soil or cutterhead retraction are all elliptical, with the major axis perpendicular to the shield advancement direction. However, the extent of ground collapse caused by discharging soil is larger than that induced by retraction failure, which is closely related to the corresponding ground loss.

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• Experimental study on punching shear capacity of slab-column joints with partial use of ultra-high performance concrete

  LI Chuang, ZHOU Yan

  Abstract: (116) HTML (0) PDF (0.00 ByteKB) (0)

  This study conducted through the tests of 9 interior slab-column joint specimens with partial utilization of ultra-high performance concrete (UHPC) under concentrated vertical loads to explore a new method for enhancing the punching shear resistance of such joints. This test examined the impact of UHPC on the performance and damage mechanisms of slab-column joints. The test parameters included the dimensions of the UHPC area as well as the volume fraction of steel fiber present in the UHPC. The test results indicated that UHPC had the potential to substantially enhance the ductility and punching shear capacity of slab-column joints. When UHPC was used locally in an area of one times the slab thickness from the column face, the ductility and punching shear capacity for specimens with a fiber ratio of 0.8% increased by 126% and 64%, respectively, compared to the specimens made entirely of normal concrete (NC). Therefore, the overall performance of the UHPC and NC composite slab-column joints can be enhanced with the rational UHPC area and volume fraction of steel fibers in practice. In this paper, the punching shear resistance of each specimen was estimated by three different codes. It was found that all the code equations either overestimated or underestimated the punching shear capacity within the UHPC region. Therefore, further research is necessary to explore the punching shear capacity of UHPC slabs. The finite element software ABAQUS was used to establish the force analysis model of specimens. The simulation results agree well with the experimental results. Based on this model, the effect of different UHPC area on the punching shear capacity of the specimens was further investigated. Finally, an empirical formula for estimating the punching shear capacity of UHPC–NC composite slab-column joints is proposed. The predicted values obtained from this formula show good agreement with the numerical results.

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• Analysis of Lateral Bearing Behavior and Reliability for Flexible Monopiles in Spatially Variable Sandy Soils

  tongquangang, wangchendi, chenyingjie, zhangyunfei, yijiangtao

  Abstract: (42) HTML (0) PDF (0.00 ByteKB) (0)

  Geotechnical materials exhibit significant heterogeneity in their spatial distribution due to the combined effects of sedimentation processes, geological history, and environmental factors. Traditional design methods for horizontally loaded piles assume that soil parameters are spatially homogeneous constants and use idealized calculation models for analysis, which often leads to an overestimation or underestimation of the horizontal bearing capacity of pile foundations. This study employs the stochastic finite element method and selects the internal friction angle of sandy soil as a key variable parameter. It systematically investigates the influence mechanisms of the spatial variability coefficient of sandy soil, horizontal and vertical correlation distances on the horizontal bearing characteristics and failure probability of flexible single piles. The results show that the spatial variability of the internal friction angle of sandy soil significantly affects the horizontal bearing performance of the pile foundation: as the variability coefficient of the internal friction angle and the vertical correlation length increase, the mean horizontal ultimate bearing capacity decreases, while the coefficient of variation of the bearing capacity increases. This indicates that the spatial variability of the soil not only reduces the average bearing capacity but also increases the dispersion of the bearing capacity. Further analysis of seven typical variability combinations reveals that the failure probability of flexible single piles generally exceeds 50%. Based on these findings, this study innovatively establishes an explicit functional relationship between the safety factor and failure probability, providing a theoretical foundation and practical tool for the reliability design of horizontally loaded piles.

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• Experimental study on performance connection of threaded sleeve of steel tie rod

  Huang Hao, Zhou Ting, Yang Wei, Wang Xinyan

  Abstract: (65) HTML (0) PDF (0.00 ByteKB) (0)

  As the core load-transferring component in long-span suspended structures, the reliability of sleeve connection joints in steel tie rods directly affects the overall structural safety. To investigate the influence of thread engagement depth and sleeve wall thickness ratio on joint bearing performance, this study conducted tensile tests on 12 full-scale specimens with different parameter combinations (6 groups for each parameter), analyzing typical failure modes and their evolution patterns under various configurations. A refined numerical analysis system considering threaded contact was established using ABAQUS finite element models. The results demonstrate significant parametric sensitivity in both load-bearing capacity and ductility characteristics. When thread engagement depth is less than 1.0d, uneven interfacial shear stress distribution leads to thread pull-out failure. However, when depth reaches 1.0d or more, the failure mode transitions to ductile necking fracture dominated by rod deformation, with maximum bearing capacity stabilizing. For sleeve wall thickness ratios below 0.225, brittle fracture occurs in sleeves due to stress concentration. When the ratio reaches 0.225 or higher, optimized stress distribution through enhanced sleeve stiffness shifts the failure mode to rod plastic deformation. Comparative analysis between theoretical models and experimental data validated critical condition equations for three failure modes, showing good consistency with error is within 4%. The study ultimately proposes a dual-control parameter design criterion: thread engagement depth should be ≥1.1d combined with sleeve wall thickness ratio ≥0.225, ensuring both high load-bearing capacity and controllable ductility for connection systems. This provides theoretical guidance for engineering applications.

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• Optimized dynamic stability analysis of three-dimensional dam slope considering strain-softening of rockfill

  PANG Rui, YAO Hao-yu, XU Ming-yang, ZHOU Yang, XU Bin

  Abstract: (42) HTML (0) PDF (0.00 ByteKB) (0)

  The stability analysis of high earth-rockfill dam is mostly limited to two-dimensional situation, and there is no suitable three-dimensional stability analysis method. In addition, the rockfill material of earth-rockfill dam is prone to strain softening under strong earthquakes, which affects the seismic performance of the dam. It is necessary to develop a three-dimensional stability analysis method for high dams that can take the softening effect into account. Firstly, a three-dimensional static and dynamic stability analysis method for high earth-rock dams is proposed based on the finite element sliding surface stress method combined with the optimized horn-shaped three-dimensional damage mechanism. Then, the relationship between post-peak strength and post-peak shear strain is obtained by processing the triaxial test results of rockfill in order to consider the impact of the softening effect of the rockfill material. Finally, the developed stability analysis framework is applied to analysis the static and dynamic stability of three-dimensional high earth-rockfill dam, and is compared with the two-dimensional case. The results show that the slippage with and without considering the softening effect differ significantly, and this difference increases as the cumulative slippage increases. Compared with the three-dimensional stability analysis, the two-dimensional stability analysis based on cumulative slippage tends to underestimate the seismic stability of the dam slope.

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• Residential Air Conditioning Energy Fractal Analysis and Short-Term Prediction Model Optimization

  FU CHENGHAO, Liu Meng, Li Ziqiao

  Abstract: (57) HTML (0) PDF (0.00 ByteKB) (0)

  The energy consumption of air conditioning systems in residential buildings is significantly influenced by the diversity of user behaviors. Traditional statistical features struggle to accurately discern differences in usage patterns under conditions of inadequate data quality, rendering short-term energy consumption prediction models challenged in balancing accuracy and computational cost. Fractal theory, however, offers a distinct advantage in addressing these challenges by quantifying the nonlinear and multi-scale complexity of time series data, thereby enabling the differentiation of user behavior patterns. This study proposes a short-term energy consumption prediction framework that integrates fractal analysis with a data-driven approach. By employing fractal features, users are categorized into low, medium, and high complexity groups, with input data and features optimized across sliding window size, data volume, and feature selection to mitigate noise interference, preserve key patterns, and balance prediction accuracy with computational efficiency.. Based on summer residential air conditioning data, the study finds that sliding window size is negatively correlated with complexity: low-complexity groups prefer longer windows, while medium- and high-complexity groups require shorter ones. For data volume, low- and medium-complexity groups need less, whereas high-complexity groups demand more comprehensive data. In feature selection, low- and medium-complexity groups rely on large-fluctuation features, while high-complexity groups depend on small-fluctuation features. Validation with a 2000-household sample demonstrates a MAPE of 9.82% and a CV-RMSE of 11.40%, achieving a 41.52% error reduction compared to per-household prediction models while significantly saving computational time. By combining fractal features with K-means clustering and LSTM networks, this study overcomes limitations of conventional approaches, offering an efficient solution for short-term energy consumption prediction in residential settings.

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• Investigation of Hydro-Thermal-Salinity Distribution in Subgrade Saline Soils of Cold and Arid Regions

  YUAN Chao, ZHANG Tong wei, LIU Zi jian, YAN Lu chun, HONG Wei, LIU Qi, WU Zi long

  Abstract: (85) HTML (0) PDF (0.00 ByteKB) (0)

  Saline soils, which are widely distributed in the cold and arid regions of northwest China, are prone to salt swelling and solution-induced subsidence under changing hydrothermal conditions. Due to variations in evaporation boundaries, the distributions of hydro-thermal-salt fields and the stratified deformation behaviors of different subgrade structures remain poorly understood. This study, based on the Liuyuan–Dunhuang Expressway project, investigated three types of pavement structures: concrete shoulder with a semi-rigid base, gravel shoulder with a semi-rigid base, and gravel shoulder with a flexible base. Multi-physical field monitoring was carried out, including measurements of volumetric water content, temperature, and electrical conductivity. For each pavement structure, 30 temperature sensors and 9 soil water-salt composite sensors were installed. To better interpret the physical significance of the monitoring data, coupled hydro-thermal-mechanical-salt numerical simulations were subsequently conducted. The monitoring results indicate that the gravel shoulder combined with a flexible base provides advantages in thermal insulation and in inhibiting water and salt migration. Under identical conditions, this structure improves road drainage, enhances evaporation capacity, and strengthens thermal insulation performance. Therefore, in saline soil environments, this structural configuration effectively mitigates the accumulation of water and salt in the subgrade, thereby extending its service life.

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• Study on the Compressive Bearing Performance of Masonry Walls Reinforced with Double-Sided Prefabricated Autoclaved Aerated Concrete Panels

  ZHOU Yongming, PAN Shuhan, SHI Tao, GAO Chao, LI Guohua, XU Weibin, CHEN Ruisheng

  Abstract: (62) HTML (0) PDF (0.00 ByteKB) (0)

  To investigate the compressive bearing performance of brick masonry walls reinforced with prefabricated autoclaved aerated concrete (AAC) panels, two brick masonry walls reinforced with double-sided prefabricated AAC panels and two unreinforced brick masonry walls as control specimens were designed and fabricated. Through compressive bearing capacity tests and finite element simulation software, the failure modes and compressive bearing performance of the brick masonry walls reinforced with prefabricated AAC panels were studied. Both the experimental and simulation results indicate that the reinforced layer of prefabricated AAC panels can provide confinement to the wall, delaying the cracking of the brick masonry wall and enhancing its compressive bearing capacity, ductility, and integrity. Compared to the unreinforced masonry walls, the compressive bearing capacity of the double-sided prefabricated AAC panel-reinforced walls increased by a maximum of 71.3% in the tests and by a maximum of 67.5% in the simulations. Based on the failure modes of the specimens and considering the contribution of the prefabricated autoclaved aerated concrete panel reinforcement layer, a formula for calculating the compressive bearing capacity of this reinforcement method was proposed. Furthermore, the strength utilization coefficient of autoclaved aerated concrete for this calculation method was fitted and determined based on the experimental and simulation results.

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• The influence and kinetic analysis of limestone powder dosage and fineness on cement hydration process

  ZHAO Boxun, SUN Huamin, TAN Yong, MIAO Chaojie, WU Hao, YU Linwen

  Abstract: (100) HTML (0) PDF (0.00 ByteKB) (0)

  In this study, a microcalorimeter was used to analyze the hydration heat of cement pastes with different contents and fineness of limestone powder. Based on the Krstulovi?-Dabi? model, the actual hydration reaction rate curve and the theoretical hydration reaction rate curve of each stage were obtained. The reaction kinetics related parameters including degree of reaction, reaction order, and reaction rate constants for the NG, I, and D stages were calculated to analyze the influence of limestone powder content and fineness on cement hydration. Experimental results demonstrate that within the limestone powder dosage range of 0~35% and specific surface area of 465 m2/kg ~665 m2/kg, the correlated increase in both parameters enhances cement hydration kinetics, resulting in both elevated hydration heat peaks and accelerated peak occurrence. When the limestone powder content is 35%, the peak increases by 26.2% and occurs 3.17 hours earlier. Additionally, the reaction degree of the NG process (crystallization nucleation and crystal growth process) of cement hydration increases. The addition of limestone powder and the increased fineness enhance the early hydration reaction rate, while leading to a limited hydration degree in the later-stage.

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• Study on the dissolution characteristics and meso-structure damage evolution of Qixia Formation limestone under dissolution

  Zhang Limin, Wang Hai, Li Wenqiang, Li Renjie, Ji Feng

  Abstract: (73) HTML (0) PDF (0.00 ByteKB) (0)

  Carbonate rocks, widely distributed, undergo significant alterations in their macro-scale and meso-scale characteristics and mechanical properties due to dissolution processes, which may trigger geological disasters. This study investigates Permian Qixia Formation limestone, selected as the research subject, using cylindrical thin sections prepared for experimentation. Carbonate karst dissolution experiments were conducted at varying temperatures (0°C, 15°C, 25°C, and 40°C) and solution pH values (pH = 1, 3, 5, 7) to assess the mass loss of carbonate rocks and changes in solution pH due to dissolution. Scanning electron microscopy (SEM) was utilized to examine changes in fracture and porosity of the carbonate rock and to explore the mechanism of meso-structural damage evolution. The results indicate that both rock mass loss and solution pH increase with dissolution time, while the dissolution rate decreases over time. At pH = 1, the cumulative mass loss of the sample reaches 11%, with a maximum mass loss rate of 1.3%/h. Both the mass loss rate and total loss are several orders of magnitude greater compared to conditions where pH > 3. Furthermore, the rate of pH increase at pH = 1 is significantly slower than under other pH conditions. A solution pH of 6 serves as the threshold for distinguishing mass loss characteristics during dissolution: when pH < 6, chemical dissolution predominates, whereas physical erosion dominates when pH > 6. Under identical pH conditions, higher test temperatures result in greater cumulative rock mass loss and higher post-experiment solution pH. Additionally, carbonate karst erosion exhibits beaded dissolution pores along macro-scale fractures, cystic porosity at fracture tips, and enhanced dissolution along grain boundaries at the meso-scale. The findings provide an important scientific foundation for further exploring the dissolution process of carbonate rocks.

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• Mechanical properties of different fiber reinforced ultra-high performance concrete after high temperature

  Wu Pengtao, Zhang Xueyan, Liu Zhongxian

  Abstract: (152) HTML (0) PDF (0.00 ByteKB) (0)

  The apparent characteristics and mechanical properties of ultra-high performance concrete reinforced by different fibers were studied by using high temperature heating and high temperature compression strength tests on the cylinders. Aiming at different temperatures, fiber content and fiber types, 108 specimens of ultra-high performance concrete cylinders were prepared, and uniaxial compression tests were carried out at 6 target temperatures (20℃, 200℃, 400℃, 600℃, 800℃, 1000℃). The effects of single steel fiber, mixed steel fiber of different lengths, mixed steel fiber and polypropylene fiber, mixed steel fiber and polyethylene fiber on high temperature cracking and compressive strength of ultra-high performance concrete were compared. The results show: with the increase of temperature, the damage degree of ultra-high performance concrete becomes more serious. After high temperature action, the mixed steel fiber and polypropylene fiber ultra-high performance concrete can also maintain good integrity and high compressive strength, and can still maintain 30% residual strength after high temperature action at 1000℃. With the increase of temperature, the compressive strength of ultra-high performance concrete increases and then decreases, and the ductility of ultra-high performance concrete is enhanced by high temperature.

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• Regional energy and economic affordability study of air source heat pump electric heating in rural areas of northern China

  Xiaoyi Chen, Ziqiao Li, Wenmao Zeng, Longkang Dai, Xiangwei Qiu, Meng Liu

  Abstract: (81) HTML (0) PDF (0.00 ByteKB) (0)

  Clean heating can mitigate pollution issues in northern China, and affordable cost and security of power supply are keys to promoting clean heating. Therefore, this paper proposed a suitability-evaluation framework for ASHP (air source heat pump) heating in rural areas of northern China from a regional perspective. By establishing regional energy indicators and economic indicators, assess the energy and economic affordability of ASHP heating in rural areas based on scenario analysis. The results showed that regional energy affordability gradually decreased with the increase in residents" heating demand, which is influenced by the regional energy infrastructure, household size, and living habits. Furthermore, in scenarios ranging from basic to high demand, the proportion of heating operation costs in per capita disposable income (PCDI) is less than 10%, showing a high level of economic affordability. However, under medium to high-demand scenarios, the initial investment accounts for a proportion of 10.4% to 24.9% of the PCDI, indicating weak economic affordability. Rural residents require financial subsidies, otherwise, residents may face energy poverty and their acceptance of ASHP heating systems may also decrease. This research provides valuable insights for rural clean heating energy planning and policy-making.

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• Pore Tortuosity Calculation Model of Soil-Rock Mixture Considering Particle Breakage

  Zeng Ling, Qi Yan, Zhang Hong Ri, Wen Wei, Tang Jing, Xiong Jian Ping, Song Jian Ping, Chen Jing Cheng, Wang Wen Guang, Li You Jun, Long Tong Bo, Xu Zi Hang, Li Lin Le

  Abstract: (51) HTML (0) PDF (0.00 ByteKB) (0)

  Pore tortuosity represents the complexity of fluid flow paths in soil and is a key parameter for analyzing soil infiltration properties. However, most existing pore tortuosity models are general-purpose, making them less suitable for soil-rock mixtures, which exhibit distinct characteristics such as a wide grain size distribution and complex pore structure. To develop a computational model for soil-rock mixtures that accounts for the effects of coarse particle crushing on pore tortuosity, soil particles were assumed to be circular with varying sizes. And a lognormal distribution function was used to represent soil gradation in different cases, while obstruction angle and anisotropy parameter were introduced to characterize the particle dispersion pattern. A pore tortuosity calculation model influenced by multiple factors was finally developed based on the laminar flow of fluids in soil-rock mixtures. Using programming software and numerical simulation methods, seepage simulations were performed on soil-rock mixtures with varying soil gradation and initial porosity. The relative error between the theoretical and simulation results was within 2%, demonstrating the validity of the proposed model. The analysis of the model influencing factors indicated that changes in particle gradation significantly affect pore tortuosity. Pore tortuosity decreased as coarse particle content increased, and the absence of macroparticles further reduced pore tortuosity. As the obstruction angle and anisotropy parameters increased, the pore tortuosity also increased. A significant negative interaction was observed between porosity and the other factors. When porosity is high, pore tortuosity converges to 1, indicating that porosity becomes the dominant factor affecting pore tortuosity. Among the above four influencing factors, the degree of influence on pore tortuosity in the soil-rock mixture followed the order: particle gradation (mass fractal dimension) > anisotropy parameter > porosity > obstruction angle. The grey correlation values of the mass fractal dimension and anisotropy parameter exceeded 0.95, indicating a strong correlation.

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• Experimental Study on Superelasticity of Large Diameter NiTi-SMA Bars under Different Heat Treatment Processes

  Tian Penggang, Wen Jingbei, YANG Wenjie, LIU Kangning, Wang Jiajia, XIONG Ergang

  Abstract: (85) HTML (0) PDF (0.00 ByteKB) (0)

  Adding large-diameter hyperelastic NiTi shape memory alloy (NiTi-SMA) bars to damping elements can achieve good self centering ability. However, due to the high sensitivity of SMA materials to temperature, different heat treatment processes can have a certain impact on the mechanical properties of NiTi-SMA bars, resulting in varying degrees of influence on the energy dissipation and self centering ability of dampers or supports containing NiTi-SMA bars. Therefore, it is necessary to explore the effects of different heat treatment processes on the mechanical properties of large-diameter NiTi-SMA bars. This article first conducted different heat treatment processes on 7 Ni-59.9% atTi bars with a working section diameter of 9mm, followed by amplification cyclic tensile tests to investigate the effects of different heat treatment processes and amplification cyclic tensile tests on the stress-strain relationship, residual strain, energy dissipation capacity, and other properties of the specimens. The research results indicate that appropriate heat treatment can significantly improve the superelasticity of NiTi-SMA bars, with a typical flag shaped stress-strain curve. The optimal heat treatment temperature and duration for NiTi-SMA bars with a working diameter of 9mm are 400 ° C and 30min, respectively; The closer to the optimal heat treatment process, the more stable the energy dissipation capacity, secant stiffness, and equivalent damping ratio of the specimen become.

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• The influence of configuration differences of titanium oxide anode reactors on the treatment effect of landfill leachate and the transformation of dissolved organic matter

  WeiLuYing, ZhaoJianShu, ChenYongYi, JinQingHai, WangSiBo, HeDi

  Abstract: (64) HTML (0) PDF (0.00 ByteKB) (0)

  The anodic oxidation method has strong oxidation capacity and low secondary pollution, making it highly promising in the treatment of landfill leachate. This study constructed a flow-by and flow-through reactors using Ti4O7 electrodes and systematically investigated their performance in the deep treatment of leachate effluent. The results showed that in the Flow-by mode, with a current density of 60 mA/cm2, pH of 8, and Cl- concentration of 200 mg/L, the operation for 240 minutes resulted in a COD removal rate of 77.47%, significantly higher than that of the Flow-through mode (60.56%). The Flow-by mode can also more effectively alter the composition of DOM, with higher pre-treatment efficiency, and can mineralize and remove most of the dissolved organic matter. In conclusion, the Ti4O7 anode reactor has significant advantages in treating landfill leachate.

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• Construction of carbon fiber-anchored ferromanganese bimetallic electrocatalyst and efficient degradation mechanism of thiamethoxam

  FENG Yao, QIU Jinli, CHAN Huifang, LIU Fuqiang

  Abstract: (99) HTML (0) PDF (0.00 ByteKB) (0)

  Bimetallic electrocatalysts can leverage synergistic effects to efficiently catalyze the degradation of neonicotinoid pesticides, but their application is constrained by diminished active sites due to the aggregation of metal nanoparticles. By anchoring metallic species onto nanofibers through electrospinning and achieving in-situ integration of metal oxides with carbon fibers via thermal treatment, we successfully constructed an iron-manganese bimetallic electrocatalyst (FM@N-CNF), featuring uniformly dispersed metal oxides with an average particle size of 6 nm. Electrochemical characterization confirmed that FM@N-CNF exhibits superior electrochemical active surface area and electron transfer capability compared to monometallic catalysts. When employed as a cathode material at -0.5 V vs. SCE, FM@N-CNF achieved complete degradation of thiamethoxam within 90 minutes and maintained degradation rates above 80% over 10 consecutive cycles. The catalyst demonstrated excellent environmental adaptability under various conditions, including pollutant concentrations (5 ~ 100 ppm), pH (3 ~ 11), and coexistence of common inorganic salts. Quenching experiments in combination with electron paramagnetic resonance (EPR) spectroscopy consistently identified singlet oxygen (1O?) as the predominant reactive oxygen species. Liquid chromatography-mass spectrometry analysis revealed that the degradation pathway of thiamethoxam primarily involves carboxylation and carbonyl addition reactions.

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• Inversion of Chl a spatiotemporal distribution and analysis of driving factors based on Landsat-8 data

  zhangziwei, guoxianhua, wangyazhu, liuqianchen

  Abstract: (219) HTML (0) PDF (0.00 ByteKB) (0)

  Chlorophyll-a (Chla), primarily sourced from phytoplankton, serves as a pivotal indicator for water eutrophication. It stands as a fundamental metric for gauging eutrophication levels, biophysical conditions, and primary productivity within lake ecosystems. Focusing on Taihu Lake as the study area, this research utilizes Landsat 8 OLI data alongside measured point data to establish a partial least squares model for inversion via a semi-empirical approach. Preliminary experimental findings indicate that the derived model and parameters effectively capture Chla concentrations in Taihu Lake over the past nine years (2015-2024). Building upon this foundation, the study integrates physical geography and socio-economic factors to analyze trends in Chla concentrations and their underlying causes. Consequently, this paper furnishes a semi-empirical model, parameter scheme, and a comprehensive long-term dataset of Chla concentration dynamics in Taihu Lake, offering robust support for future governance endeavors concerning the lake"s ecological restoration.

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• Investigation on catalytic ozonation of coal chemical RO concentrated water by Mn-Co@4A

  WANG Ziran, SUN Wenquan, ZHOU Jun, WU Deyong, QIANG Jinfeng, SUN Yongjun

  Abstract: (92) HTML (0) PDF (0.00 ByteKB) (0)

  In this study, Mn-Co@4A catalyst was investigated for catalytic ozonation of coal chemical RO concentrated water. The Mn-Co@4A catalyst was characterized by SEM, EDS, XRF and XRD. The effects of working conditions (initial pH, catalyst filling ratio, ozone dosage, reactor height-diameter ratio) on the catalytic efficiency of ozone catalytic oxidation wastewater were studied. The stability of Mn-Co@4A catalyst was evaluated under optimal conditions, and the mechanism of water treatment was analyzed by UV absorption spectroscopy, three-dimensional fluorescence spectroscopy and free radical quenching experiments. The results show that Mn-Co@4A catalyst has good catalytic performance and stability. Under the conditions of initial pH = 7.64 (raw water), catalyst filling rate of 5%, ozone dosage of 6 mg/L/min, and reaction column height-diameter ratio of 6 : 1, the best COD removal rate of coal chemical RO concentrated water can reach 69.92%. With the increase of oxidation time, the conjugated structural substances, unsaturated ketones and protein-like substances in the RO concentrated water of coal chemical industry were gradually effectively degraded, and .OH and O2.- played the main role in the oxidation of organic matter.

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• Adsorption performance and mechanism of manganese ferrite modified biochar for phosphate

  Zhao rui

  Abstract: (149) HTML (0) PDF (0.00 ByteKB) (0)

  Excessive phosphorus discharge is one of the primary factors contributing to water eutrophication, making the development of efficient and cost-effective technologies for phosphorus-containing wastewater treatment crucial for water environment protection. In this study, bamboo biochar (BC) was prepared through pyrolysis using moso bamboo as the raw material, and manganese ferrite-modified biochar (MnFe2O4/Biochar, MB) was synthesized via a hydrothermal method for the removal of phosphate (H2PO42-) from wastewater. The effects of factors such as pH, adsorption time, and initial concentration on the adsorption performance were investigated. The results indicated that the adsorption capacity of MB for phosphate decreased with increasing pH, reaching a maximum capacity of 4.59 mg/g at pH=4.0. The adsorption process followed the Freundlich isotherm model and the pseudo-second-order kinetic model. The high saturation magnetization value of MB (48.28 emu/g) demonstrated its ease of separation. Characterization results revealed that the adsorption mechanism primarily involved the exchange of hydroxyl groups in Mn-OH with phosphate to form inner-sphere complexes. Furthermore, in actual water bodies, the presence of coexisting ions and organic matter interacted with phosphate, providing additional adsorption sites for MB and resulting in favorable phosphate removal performance. The findings of this study suggest that MB, as an efficient and easily separable adsorbent, holds significant potential for application in the treatment of phosphorus-containing wastewater.

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• Effect of corrosion behavior on mechanical properties of steel under failure mode of local anti-corrosion coating

  niukai, zhangliang, xuweihao, zhouyan, yangyang, wangjunyan, wangpengkai

  Abstract: (82) HTML (0) PDF (0.00 ByteKB) (0)

  This paper focuses on Q355B steel under the condition of local anti-corrosion coating failure to explore the rusting behavior of the steel and its impact on mechanical properties. Standard specimens in three typical local anti-corrosion coating failure modes, namely pitting corrosion, banded corrosion, and surface corrosion, were designed. Based on electrochemical tests, the rusting rate of the steel under the local anti-corrosion coating failure modes was measured, and the rusting morphology and distribution characteristics of the steel were analyzed. The starting points, propagation paths, and morphological changes of local rusting were analyzed based on the test results, and the corrosion paths and mechanisms under the local anti-corrosion coating failure modes were revealed through the corrosion surface morphology. The elastic modulus, yield point, yield strength, tensile strength, ultimate strain, and elongation after fracture of the steel under the local anti-corrosion coating failure modes were analyzed through the steel tensile tests. The results indicate that, the reduction coefficients of the elastic modulus, yield strength, and tensile strength of the steel under the local anti-corrosion coating failure modes have a linear negative correlation with the average corrosion rate; the reduction coefficients of the ultimate strain and elongation after fracture have a nonlinear correlation with the average corrosion rate. This study reveals the influence of local anti-corrosion coating failure modes on the mechanical properties of the steel, and the research results can provide references for the anti-corrosion protection of steel and the structural safety assessment.

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• Early Autogenous Shrinkage Performance of PVA-FRCC Mixed with Aeolian Sand

  Wang Yuqing, Qu Xun, Yun Zeya, Sang Dade, Liu Shuguang

  Abstract: (53) HTML (0) PDF (0.00 ByteKB) (0)

  In order to study the early autogenous shrinkage performance of polyvinyl alcohol fiber cement-based composites ( PVA-FRCC ) mixed with aeolian sand and establish a autogenous shrinkage prediction model. This paper takes aeolian sand replacement rate, fiber volume rate, water-binder ratio and sand-binder ratio as research variables. The autogenous shrinkage of the material within 7 days was tested by shrinkage test, and the influence of various factors on autogenous shrinkage was summarized. The pore fluid saturation, porosity and pore size of the specimen were tested by low-field nuclear magnetic resonance test. The influence mechanism of aeolian sand on autogenous shrinkage is revealed. The results show that aeolian sand has porous water absorption and small elastic modulus. When the water-binder ratio is small, the autogenous shrinkage increases with the increase of the replacement rate of aeolian sand. When the water-binder ratio is large, the autogenous shrinkage decreases with the increase of the replacement rate of aeolian sand. The internal curing effect of PVA fiber reduces the autogenous shrinkage. When the water-binder ratio is small, the chemical shrinkage caused by the hydration reaction increases, resulting in an increase in autogenous shrinkage ; the increase of sand-binder ratio increases the absolute content of aeolian sand, which leads to the increase of autogenous shrinkage. The overall pore size of PVA-FRCC mixed with aeolian sand is small, and the most probable pore size is about 10 nm. The increase of pore porosity after the increase of aeolian sand replacement rate is the main reason for the increase of autogenous shrinkage. Finally, considering the influence of various factors, the early autogenous shrinkage prediction model of PVA-FRCC mixed with aeolian sand was established. The calculated values of the model were in good agreement with the experimental values.

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• Influence of multiple factors on flocculent structure and rheological properties of cement slurry

  LIU Chang-qi, LIU Hao-jie, SU Lei, BAI Ji-wen, LIU Li-dong, TIAN Jiawei

  Abstract: (109) HTML (0) PDF (0.00 ByteKB) (0)

  The rheological properties is an important basis for the design of grouting parameters in geological disaster management. Rheological property of cement suspension is affected by many factors, and its mechanism is uncharted. In this study, the influence of particle size distribution on rheological property is analyzed. The focused beam reflectivity measurement system was used to measure the chord size and number of flocculated particles under different water-cement ratio, cement fineness and shear rate, and the rheological properties of slurry under the same conditions were measured. The effects of particle size distribution on rheological properties were analyzed. The results show that with the increase of water-cement ratio, cement fineness and shear rate, the chord size of flocculated particles decreases and the number of particles increases. The degree of particle flocculation increased linearly with the increase of time. The yield strength and molding viscosity decrease with the increase of water-cement ratio, and increase with the increase of cement fineness. The apparent viscosity decreases with the increase of shear rate and shows a reversible change. The change of flocculation structure is consistent with the change of rheological properties. The water-cement ratio, cement fineness and shear rate affect the rheological properties by influencing the flocculation structure. This study reveals the change of rheological properties from the perspective of flocculation structure, which can provide guidance for the design and application of cement grout.

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• Study on the influence of filling concrete on the axial tensile performance of steel tube inner and outer flange joints

  LIU Yongsheng, Wang Hao, TAO Xin, Lin Gang, Zhang Chuanjin, Wang Qiulin

  Abstract: (78) HTML (0) PDF (0.00 ByteKB) (0)

  Steel tube inner and outer flange joints are widely used in large-span transmission towers. Filling concrete in chord has become an effective method to improve the bearing capacity and the stress on steel tubes. In order to reveal the influence of filled-concrete on the mechanical properties of steel tube inner and outer flange joints under axial tensile load, two concrete-filled inner and outer flange joints (CFIOF) and two inner and outer flange joints (IOF) were designed for axial tensile tests. The failure mode, flange opening deformation, strain development of key parts and axial tension ratio β of outer and inner bolts were compared and analyzed. Then, a CFIOF finite element model was established and validated for parameter analysis to reveal the influence of flange thickness, bolt spacing, and concrete strength on β. The study found that the failure mode of CFIOF is basically the same as that of IOF, both of which are flange plate opening, accompanied by deformation of the bolt thread area. When the opening deformation is the same, the bearing capacity can be increased by more than 5%. Filling concrete can make the inner and outer bolts more uniformly under stress. As the thickness of the flange plate increases, β shows a trend of first increasing and then decreasing, gradually approaching one. With the increase of bolt spacing and concrete strength, β decreases gradually and tends to 1. The effect of concrete strength on β is the smallest.

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• Influence of Control Stability of Construction Parameters on Surface Settlement Induced by Shield Tunneling in Soft Soil

  hehaini, zhangrongjun, yangdong, taofengjuan, zhengjunjie

  Abstract: (58) HTML (0) PDF (0.00 ByteKB) (0)

  In the researches on surface settlement induced by shield tunneling, most of the construction parameters are regarded as deterministic values, ignoring their variability during the control process. This paper aims to investigate the relationship between the control stability of construction parameters control and the surface settlement caused by shield tunneling. Based on the shield tunneling project of a certain section of Wuhan Metro Line 2, a three-dimensional numerical model is established to simulate the whole process of shield tunneling. The influence of the variation level of chamber earth pressure, over-excavation gap, and grouting pressure on the surface settlement is investigated. An effort is also made to gain insight into the influence area of different construction parameters. The results show that the control stability of construction parameters control during the shield tunneling process has a great influence on the surface settlement, and the dispersion degree of surface settlement is positively correlated with the variation level of construction parameters. Moreover, the uncertain surface settlement is affected by the control stability of construction parameters within the primary impact area. According to the numerical analyses, the control standards for the coefficient of variation of the construction parameters were obtained. The research results provide a reference for the construction control and risk assessment of shield tunnel engineering.

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• Development and application of particle-scale tensile strength testing system for biocemented bond

  Yan Jiang, Wu Huanran, Xiao Yang, Liu Hanlong

  Abstract: (231) HTML (0) PDF (0.00 ByteKB) (0)

  Biocementation technology is an emerging eco-friendly cementation technology that utilizes the metabolic activity of microorganisms to cement geomaterials. The particle-scale studies on the strength of biocemented bonds remain rare, although extensive research have been conducted on the mechanical properties of biocemented bonds at the element or field scale. Traditional geotechnical testing equipment is insufficient for accurately measuring the strength of biocemented bonds at the particle scale. To precisely measure the mechanical properties of biocemented bonds at the particle scale, a particle-scale tensile testing system for biocemented bonds was developed and the tensile strength tests for particle-scale biocemented bonds was carried out with this system. This testing system was comprised of a displacement control module, a tension measurement module, a specimen fixing module, and an imaging observation and recording module. The displacement control module ensures the stable operation of the loading stage, while the tension measurement module accurately measures and records the evolution of tensile force. The specimen fixing module securely holds specimens to prevent slippage or misalignment. The imaging observation and recording module captures and records the failure behavior of the specimen during the tensile process in real time. Detailed descriptions of specimen preparation, the testing process, and tensile test results were provided. The test results demonstrate that the testing system exhibits high precision and excellent stability. It effectively measures the tensile strength and clearly captures the failure characteristics of biocemented bonds upon tensile loading, providing reliable experimental system for the study of the mechanical properties of biocemented geomaterials.

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• Mechanical properties and microstructural analysis of lignin fibler-lime composite expansive soils

  LIU Haotong, WANG Yejiao, WANG Taian, GUO Zhaomin

  Abstract: (181) HTML (0) PDF (0.00 ByteKB) (0)

  Expansive soil is a typically problematic soil that exhibits the engineering characteristics of swelling and shrinkage. It is highly sensitive to climatic changes, often leading to engineering disasters such as slope instability and landslides. While traditional inorganic chemical modifiers (such as lime, cement, etc.) can effectively improve soil strength, these modifiers are associated with environmental issues, particularly high carbon emissions. This study investigated the use of a novel green, low-carbon material—lignin fiber (LF)—for the modification of expansive soil. Unconfined compressive strength test, direct shear test, free swell test, mercury intrusion porosimetry, and scanning electron microscope were performed to analyze the mechanical properties of lignin fiber improved expansive soil. The effects of modifier dosage and curing age on the mechanical properties and microstructure of lignin fiber-lime composite-treated soil were also studied. The results indicated that 8% lignin fiber significantly improved both the shear and compressive strengths of expansive soil. After the optimal treatment, the mechanical properties of the composite improved soil were comparable to those of 4% lime-treated soil. Lignin fiber can effectively enhance the micro-structure of expansive soil by enhancing the bonds among soil particles. The results illustrated that lignin fiber, as a new low-carbon material, can significantly improve the engineering properties of expansive soil, to partially replace or reduce the use of traditional modifiers in the field of soil improvement.

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• Study on the Mechanical Properties and Acoustic Emission Characteristics of Sandstone with Different Water Contents under Wet-Dry Cycles

  LI YANJUN, YU PENG, SHI JINQUAN

  Abstract: (113) HTML (0) PDF (0.00 ByteKB) (0)

  This study aims to investigate the mechanical properties and acoustic emission characteristics of sandstone with different moisture contents under the action of wet-dry cycles. The sandstone samples were sourced from the surrounding rock of a subway station tunnel project in Chongqing. The samples underwent 0, 10, 20, and 30 wet-dry cycles, and the tests were conducted by controlling the moisture content of the sandstone at different cycle stages (dry, 1.2%, 2.4%, 3.6%, and saturated). Uniaxial compression tests and acoustic emission monitoring were performed, along with Scanning Electron Microscope (SEM) analysis to examine the microstructure of sandstone after different numbers of wet-dry cycles. The results indicate that as the number of wet-dry cycles increases, the pore structure of the sandstone becomes more complex, with increased cracks and the detachment of crystal particles, leading to pronounced microstructural deterioration. The uniaxial compressive strength of the sandstone decreases, and the impact of moisture content on strength becomes more significant. Additionally, the increase in wet-dry cycles and moisture content significantly reduces the level of acoustic emission activity during the failure process, while also mitigating the degree of fragmentation, reflecting the weakening of internal microfracture expansion and energy release. The study reveals a synergistic effect of wet-dry cycles and moisture content on the deterioration mechanism of sandstone.

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• Study on the Mechanical Response Characteristics of Surrounding Rock during In-Situ Excavation of Large-Section Tunnel

  mazhiguo, liulei, songwenming, zhaoyingai, daiyiming, lvxiangfeng

  Abstract: (100) HTML (0) PDF (0.00 ByteKB) (0)

  The in-situ excavation process of large-section highway tunnels causes significant disturbance to the surrounding rock and poses high construction risks. However, research on the mechanical characteristics of the surrounding rock during in-situ excavation of tunnels is still limited. This paper investigates the mechanical characteristics of surrounding rock under different excavation methods using physical model experiments and a simplified stress model. The results of the tunnel excavation physical model test show that the displacement variation is the largest in the single-sided borehole excavation method, the surrounding rock pressure accumulates at the arch shoulder in the single-sided step excavation method, and the displacement is the smallest with a more uniform surrounding rock pressure distribution in the single-sided CD excavation method. The simplified model analysis of surrounding rock stress indicates that the displacement at the arch foot is larger than at the crown, and the greater the damage degree of the surrounding rock, the larger the displacement. Field measurements confirm that model test values of rock pressure and displacement align closely with measured values, showing similar displacement trends. When the damage coefficient D is 0.2, model values under both methods accurately reflect the measurements. Moreover, the single-sided CD method is more favorable for long-term rock stability. These findings provide theoretical guidance for similar large-section tunnel projects.

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• The influence of stiffeners on the stress performance of transition nodes of tree shaped column cover plates with irregular steel pipes

  xujinmeng, xionggang, xieqiang

  Abstract: (113) HTML (0) PDF (0.00 ByteKB) (0)

  The construction of irregular steel pipe tree shaped column nodes is complex, and the use of cover plates to connect the trunk and branches can greatly reduce the difficulty of construction. Understanding the influence of cover plate stiffeners on the mechanical properties of such nodes is of great significance for guiding the design of similar projects. This article takes the special-shaped steel pipe tree column at Chongqing East Station as an example, and conducts scaled tests on two nodes with or without stiffeners to study the influence of stiffeners on key indicators such as force transmission mechanism, stress distribution and level, node failure mode, and node bearing capacity in the node area of the special-shaped steel pipe tree column. The research results indicate that the stiffness of the cover plate is greatly improved after the installation of stiffeners; After setting the stiffeners, the stress distribution in the node area, especially in the cover plate, tends to flatten and the peak stress decreases; Similar to nodes without stiffeners, in the later stage of loading, nodes with stiffeners experienced strength and local instability failure at the roots of the branches. However, with stiffeners, the degree of local bulging of the cover plate and node area trunk was significantly reduced; The bearing capacity of the node is significantly improved after the installation of stiffeners.

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• Influence of basalt fiber content on alkali-activated hardening of lunar regolith simulant

  Hua Jianmin, Yi Haolan, Xue Xuanyi, Zhan Jianghuai, Xiao Chang

  Abstract: (102) HTML (0) PDF (0.00 ByteKB) (0)

  In-situ resource-based construction technology can greatly reduce the cost of lunar surface base construction and realize high-quality operation and maintenance. How to make full use of in-situ resources to prepare high-performance building structure materials has become a hot topic in current research. In this study, geopolymers are prepared by lunar regolith simulant and reinforced with basalt fibers to enhance the mechanical properties of the materials. Exploring the effects of strong/weak alkali solutions and basalt fiber content on damage patterns, mechanical properties of lunar regolith simulant. The results of the study showed that the incorporation of basalt fibers changed the damage pattern of lunar regolith simulant and increased the deformation capacity of lunar regolith simulant. Under the condition of strong alkali solution excitation, the optimal content of basalt fiber was 0.2%; under the condition of weak alkali, the optimal content was 0.1%. The compressive and flexural strengths of the lunar regolith simulant tended to increase and then decrease with the increase of fiber content. Compared with the strong alkaline environment, the basalt fiber content had a more significant effect on the lunar regolith simulant in the weak alkaline environment.

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• Research progress on recycling and utilization of brick-concrete

  Jiao Yang, Fang Xiangwei, Shen Chun-ni, Tian Jing, Huang Sheng, Jiang Wen-chen

  Abstract: (202) HTML (0) PDF (0.00 ByteKB) (0)

  The iterative renewal of the brick-concrete structure will produce a large amount of brick-concrete construction waste, and the resource utilization of brick-concrete construction waste can effectively solve the shortage of natural sand and gravel resources as well as alleviate the harm of construction waste landfill. The brick-concrete recycled materials are divided into three categories according to the particle size: brick recycled coarse aggregate, fine aggregate and powder. Brick-concrete recycled coarse aggregate can be used as aggregate for recycled concrete and base course of road base project; recycled fine aggregate is often used in recycled mortar, recycled blocks and improved performance of soil /cured soil and so on. The chemical composition of brick-concrete recycled powder is similar to cement, lime powder, fly ash, etc., which can be used as cementitious materials through ion exchange, generation of expanded substances, pozzolanic reaction and crystallization, etc.; Waste brick recycled powder has good pozzolanic activity, which can be used as raw materials for the preparation of waste brick recycled powder base polymer cementitious materials through alkali excitation, which has good fluidity, mechanical properties and high-temperature performance, and the reaction mechanism mainly includes Si, Al monomer dissolution, monomer reconstruction, polycondensation and filling cementation. Brick-concrete recycled materials in the future should improve the performance of renewable raw materials, expansion of application way, mechanical properties and curing mechanism, disposal and application standards development and other aspects of in-depth research.

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• A CNN-LSTM structural strain response prediction method based on feature selection

  Wang Wei, JIANG SHAN, HU JIANXIU, LU GUOYUN

  Abstract: (125) HTML (0) PDF (0.00 ByteKB) (0)

  During the long-term service of a building structure, various external and internal factors can lead to the failure of key components. The structural strain response serves as an intuitive indicator of the operational status of these components. Therefore, accurately predicting the structural strain response is crucial for the long-term monitoring of building structures. In this paper, we propose a CNN-LSTM-based method for predicting structural strain responses, enhanced through feature selection, and validate it using measured data from the health monitoring system of the Pearl Tower in Northern Xinjiang. The input model’s features are determined through Pearson correlation analysis, and their importance is ranked and selected using the random forest algorithm. We developed a CNN-LSTM structural strain response prediction model and applied the Bayesian optimization algorithm to fine-tune the model’s hyperparameters, thereby enhancing its prediction accuracy. We then compared the prediction results with those obtained from conventional LSTM and BiLSTM models. The results demonstrate that the correlation coefficients between the predicted and actual values of the CNN-LSTM model at all strain measurement points exceed 0.99. This indicates the model’s superior performance in predicting the strain response of components, as well as its higher prediction accuracy compared to the LSTM and BiLSTM models.

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• Review on Resonance and Cancellation of Railway Train/Bridge

  WANG Zhi-Lu, CHEN Lei, YANG Yeong-Bin, TAN Zhong-Xu, ZENG Qing, WANG Ying-Jie

  Abstract: (476) HTML (0) PDF (0.00 ByteKB) (0)

  Resonance can lead to excessive vibration of trains and bridge structures, exacerbating fatigue and instability in bridge-track structures, further affecting the comfort and safety of train operations. Effectively eliminating resonance during the design phase and controlling resonance during service are crucial for ensuring the healthy and sustainable development of high-speed railway transportation. This paper aims to review the research progress on resonance and cancellation issues of railway train/bridge, systematically summarize the mechanisms and laws of resonance occurrence, and clarify cancellation design and resonance control methods. The paper covers six parts: basic theory of bridge resonance and cancellation, train excitation models, resonance and cancellation issues of bridges of different types, major influencing factors of bridge resonance and cancellation, bridge resonance control and field experimental research. Research shows that the conditions for bridge resonance and cancellation are influenced by boundary conditions, but generally coincide with or slightly differ from those of simply supported beams. Bridge spans and train compositions form typical bi-periodicity, this potentially results into “dual resonance” when the bridge-induced train resonance speed is equal to the train-induced bridge resonance speed. The coupling effect between trains and bridges reduces the resonance amplitude of bridges, but the actual train-bridge coupling system is stochastic and may lead to “random resonance”. For simply supported beams, the first mode dominates the resonance displacement, while the second mode has a significant impact on resonance acceleration, and higher-order mode effects can generally be ignored. For continuous beams, the second mode also generally contributes significantly to resonance displacement and cannot be ignored. Damping in bridges can effectively reduce resonance amplitudes but may also cause “leaking effects” for cancellation. When the bridge span length L is 1.5 times the characteristic length d of the train, the first-order resonance of the bridge can be effectively eliminated, which serves as the optimal span design criterion for railway bridges. Resonance conditions can be actively avoided by setting lower frequency limits for bridges and changing train compositions. Results from extensive field tests indicate that the resonance of railway bridges is predominantly characterized by the first-order vertical bending mode. This resonance shows a significant correlation with the train speed and train length (i.e., v/d).

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• Experimental study on the effect of sodium silicate enhanced microbial grouting reinforcement

  SHANG Zhiyang, PENG Jie, Renjie Wei, Liangliang Li, Zhao Jiang, DI Dai

  Abstract: (177) HTML (0) PDF (0.00 ByteKB) (0)

  Microbially induced calcium carbonate precipitation (MICP) technology has broad application value and potential in improving the mechanical properties of rock and soil. However, this method still has defects, such as low efficiency and long reinforcement periods. An appropriate amount of sodium silicate was added to the bacterial solution to enhance the efficiency of MICP reinforcement and shorten the reinforcement period based on conventional MICP. The solution tests and sand column tests were carried out, as well as the macro and micro detection tests. The enhancement effect and mechanism of sodium silicate on microbial sand fixation were studied. The results show that the bacterial activity increased by about 14 % and the amount of calcium carbonate in the sand column increased by about 7 % after adding appropriate amount of sodium silicate, and the MICP reinforcement efficiency and sample uniformity were enhanced. After 2 times of sand column reinforcement, the sample can be formed. After 10 times of reinforcement, the compressive strength of the sample is about 5.9 MPa, which is about seven times higher than that of the control group. Microscopic detection tests show that after adding sodium silicate, the hydrated calcium silicate gel generated in the environment can play a role in filling sand pores and cemented sand particles, thereby improving the strength and reinforcement efficiency of the sample. This method can provide theoretical guidance for popularising and applying microbial sand fixation.

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• Adaptive elimination method for time-lag effects in thermal displacement monitoring data of long-span bridges

  LONG Wei, SHEN Anbin, WANG Shengli, WANG Yao, DUAN Lingling, ZHOU Guangdong

  Abstract: (164) HTML (0) PDF (0.00 ByteKB) (0)

  The elimination of time-lag effects is a crucial step in enhancing the correlation between thermal displacement and temperature of long-span bridges, and improving the reliability of displacement-based structural operation damage identification. The fixed time translation method cannot capture the changes in time lags over time and is difficult to completely eliminate time-lag effects. This article uses functional data analysis methods to transform the elimination of time-lag effects into finding an optimal warping function to align thermal displacement and temperature, and proposes an adaptive elimination method for time-lag effects in thermal displacement monitoring data. Firstly, the mechanism of time-lag effects was revealed through numerical simulation. Secondly, an adaptive elimination method for time-lag effects based on phase-amplitude separation of functional data was introduced. Thirdly, the effectiveness of this method was verified using long-term monitoring data of expansion joint displacement and temperature of a large-span rail-cum-road bridge. Finally, a strategy was presented to cope with the end effect of the adaptive elimination method. The research results indicate that the thermal inertia effect formed by low thermal conductivity is the intrinsic reason for the generation of time-lag effects. The adaptive elimination method of time-lag effects can automatically find the optimal warping function for time-lag effects elimination according to the degree of time lags. The proposed method is significantly better than the fixed time translation method. The strategy of data extension can effectively remove the end effect and achieve complete elimination of time-lag effects.

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• Deformation characteristics and its ideal elastic-plastic model of fine-grained sulfate salted soil in Qinghai

  ZHANG Xinmiao, ZHANG Wen, ZHANG Ning, WANG Longxuan, YANG Miao

  Abstract: (123) HTML (0) PDF (0.00 ByteKB) (0)

  This paper conducts an in-depth study on the deformation characteristics of sulfate salted soil in the Qinghai region and proposes an ideal elastoplastic model that considers salt content and confining pressure. Firstly, through the determination of liquid plastic limit and soluble salts, it is indicated that the four typical areas are primarily composed of silty clay and clay, with sulfates being predominant. Original saline soil samples from three sampling points were selected and subjected to artificial salt washing, preparing six soil samples with different mass ratios of sodium sulfate. Secondly, consolidation undrained triaxial tests were conducted under four confining pressures and six salt contents, revealing that the stress-strain relationship of the saline soil exhibits a distinct ideal elastoplastic characteristic: a clear linear segment is visible before yielding, with no significant hardening or softening after yielding. Under the same confining pressure, the initial elastic modulus, yield stress, and shear strength all gradually decrease with increasing salt content; at the same salt content, the initial elastic modulus and yield stress increase with increasing confining pressure. Finally, based on the test phenomena, the constant initial modulus and yield point in the ideal elastoplastic model are considered as functional expressions. By using MATLAB programming analysis and parameter optimization, a model is established where the initial modulus and yield stress are linearly expressed in terms of confining pressure and salt content. This model has fewer parameters and, in addition to reflecting changes in strength, can also describe the influence of salt content and confining pressure on the initial modulus, thus providing a more accurate description of deformation for engineering reference.

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• Seismic Response Shake Table Modeling of Marine Large Diameter Group Piles

  zhangyuanyuan, DING Xuanming, ZHENG Changjie, ZHAO Jinqiao

  Abstract: (158) HTML (0) PDF (0.00 ByteKB) (0)

  China"s offshore waters are located in the Pacific Rim seismic zone, and the large-diameter group pile foundations commonly used in marine engineering are facing seismic threat.In this paper, the dynamic response characteristics of offshore large-diameter group pile foundations are investigated using 1g shaking table model tests, and the effects of large-diameter group pile foundation arrangement and different seismic inputs are investigated.The results show that, under the same conditions, the Taft seismic wave is more likely to cause liquefaction of the soil around the piles more cyclic cycles number and lower principal frequency compared with the El-Centro seismic wave; the principal frequency of the El-Centro seismic wave is closer to the intrinsic frequency of the modelled foundation, which leads to the more significant peaks in the base acceleration and bending moment responses. Under the same amount of consumables, the superporous pressure ratio response of the soil around the piles of the nine-pile arrangement is stronger than that of the four-pile arrangement; under all the loading conditions, the acceleration response of the four-pile foundation is stronger due to the fact that it is easier to liquefy in the shallow region, and the degree of liquefaction of the four-pile foundation is lower, whereas this pattern is opposite in the deeper region; the bending moment distribution of the nine-pile foundation is more uniform, and the seismic performance of the nine-pile foundation is stronger than that of the four-pile foundation. Overall, the overall seismic performance of nine-pile foundation is better.

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• Effects of moisture content and foam injection ratio on mechanical properties of high viscosity mudstone with soil pressure equilibrium shield

  Feng Lin, Zou Kunmi, Liu Guijun, Tang Weixiang, He Qihai, Zhang Wengang, Yang Yang, Sun Weixin, Yang Wenyu

  Abstract: (120) HTML (0) PDF (0.00 ByteKB) (0)

  The problems of difficult spoil discharge and cutterhead mudding pose many challenges to the advancement of earth pressure balance (EPB) shield tunneling, especially for high-viscosity shale strata, where spoil improvement is necessary. Relying on the shield tunneling project of Shuan Tunnel (Sichuan section) of Chengdu-Chongqing Central Line, foam performance evaluation, vane shear test, interface shear test, and indoor shield tunneling model tests were carried out on shale to explore the optimal concentration range of foaming agent, and the effects of water content and foam injection ratio on the normal interface force, longitudinal interface force, and cutterhead mudding were investigated. The results show that: (1) The optimal volume fraction of the foaming agent is around 3%, with the corresponding foam expansion ratio and half-life being 29.1 and 8.71 min, respectively. (2) Based on the above optimal volume fraction, with the increase of water content and foam mass ratio, the vane shear strength, direct shear strength, cohesion, internal friction angle of shale, the average pressure of jacks, and the torque under the action of unit jack pressure all decrease to varying degrees. The adhesion amount of spoil on the shield cutterhead does not change significantly, but the consistency of shale decreases, and the cutterhead mudding is improved. (3) Overall, the average advancement speed increases. The greater the average pressure of the jacks, the greater the cutterhead torque. The improvement effect of the foaming agent on shield tunneling is better than that of water content. The research results have certain reference significance for evaluating the construction of EPB shield tunneling in high-viscosity shale strata.

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• Research on characterization of rock joint surface roughness and strength prediction method considering sampling spacing

  shizhenning, baodewei, wangzihang, zhujian, zengshiyang

  Abstract: (108) HTML (0) PDF (0.00 ByteKB) (0)

  The roughness of rock joint surfaces is the most important factor in determining their shear strength. Currently, the roughness of rock joint surfaces is mostly expressed using the root mean square slope (Z2) value, which is closely related to the sampling interval in the process of digitizing joint surfaces. To further improve the calculation accuracy of rock joint surface roughness, this paper conducted research on the characterization and strength prediction methods of rock joint surface roughness considering sampling interval. The main research results are as follows: First, the roughness of joint surfaces varies among different types of rocks after splitting, with granite exhibiting the highest roughness, followed by quartzite, and then red sandstone and mudstone. Second, the Z2 values of different joint surface contour lines show a linear decrease with the increase of sampling interval. And the greater the fluctuation of the joint surface, the more obvious the influence of sampling interval on Z2 value. A calculation formula for the joint surface roughness coefficient, which considers the sampling interval, was established based on a logarithmic function. This new formula offers clearer physical meaning and higher prediction accuracy compared to the original JRC prediction model.

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• 3D geological modeling of karst mountainous areas and its application in 3D evaluation of tunnel planning

  weilai, caocong, liuzhi, gongsiyu, xiehuijun, lixingru

  Abstract: (78) HTML (0) PDF (0.00 ByteKB) (0)

  The geological environment in karst regions is inherently fragile, necessitating a suitability assessment for tunnel planning to mitigate geological issues induced by construction activities. A pressing challenge is to develop a detailed three-dimensional geological model in karst mountainous areas, which can serve as the foundation for conducting a comprehensive 3D suitability evaluation for tunnel planning.This study focuses on the Liangjiang segment of Zhongliang Mountain in Chongqing as the research area. Employing geological modeling methods and grid subdivision techniques tailored to the regional geological characteristics, a series of detailed 3D geological and attribute models have been constructed. Based on the Analytic Hierarchy Process (AHP) and a multi-level index overlay method, a 3D evaluation system for tunnel planning has been established, aligned with the local geological conditions and the current state of tunnel construction. Furthermore, the 3D evaluation results have been utilized for tunnel planning assessment and analytical applications.The findings indicate that by employing appropriate 3D modeling methods, one can construct detailed geological models in karst mountainous regions. This serves as a foundational data source and spatial analysis framework, enabling the establishment of a 3D suitability evaluation system for tunnel planning that is consistent with the local geological environment. The results provide substantial support for the planning and site selection of tunnels in karst mountainous areas and the optimization of underground space patterns in mountainous cities.

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• Experimental study of multifaceted solid waste synergistic treatment based on harmlessness and resource utilization of red mud

  YAN Lijun, YANG Junjie, WU Yalei, LI Fengmin

  Abstract: (113) HTML (0) PDF (0.00 ByteKB) (0)

  Red mud is a kind of solid waste in the production process of aluminum industry. In order to solve the waste of land resources and environmental pollution and resource utilization problems caused by long-term stockpiling, this paper adopts CGFPA curing agent with calcium carbide residue, ground granulated blast furnace slag, fly ash, phosphogypsum and graphene as components for the harmless treatment of red mud. Tests of unconfined compressive strength, acidity and alkalinity, and toxicity leaching were used to study the effects of curing agent dosing, total initial moisture content, and curing age on the strength properties, acidity and alkalinity, and toxicity leaching properties of solidified/stabilized red mud. The results show that the unconfined compressive strength of solidified/stabilized red mud increases and then decreases, while the pollutant concentration decreases and then increases, there exists an optimal total water content ratio (the ratio of the total initial water content to the liquid limit of the red mud) with the maximum strength and the lowest pollutant concentration, and that the optimal water content ratio increases linearly with the mixing ratio of the binder. The optimal water content ratios are 1.0, 1.2, 1.3, and 1.4 for 15%, 20%, 25%, and 30% mixing ratios, respectively, corresponding to the optimal total initial water content of 37.8%, 45.4%, 49.1%, and 52.9%, respectively. The pH value of the solidified/stabilized red mud decreased with the increase of the curing age, and was lower than 9.5 after 90ds; it decreased with the increase of the total water content ratio, and gradually tended to be stabilized. In addition, the concentration of pollutants in the solidified/stabilized red mud decreased gradually with the increase of binder mixing ratio, and the removal rate of seven pollutants could reach more than 80% when the mixing ratio was 30% and the total water content ratio was 1.4. The research results have certain practical significance for the harmless treatment and resource utilization of red mud.

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• Machine learning investigates the overlooked organic excitation effects in the UV/PS system by UV185

  LUO Jingyao, ZHEN Peng, LIU Yudan, LIANG Jialiang

  Abstract: (142) HTML (0) PDF (0.00 ByteKB) (0)

  The accelerated degradation of pollutants in the vacuum ultraviolet/persulfate (VUV/PS) system is often attributed to the effective excitation of H2O and persulfate (PS) by UV185. However, the direct excitation of pollutants by UV185 has been largely overlooked, which may result in an underestimation of UV185's role in pollutant degradation. To address this gap, this study integrates machine learning and density functional theory (DFT) calculations to elucidate the mechanism of UV185 in the VUV/PS system through a data-driven approach. Initially, the ground-state and excited-state molecular descriptors for 30 types of organic pollutants were derived via DFT calculations and used as input parameters. Subsequently, a stochastic forest model was employed to predict the degradation kinetic constants and mineralization rates of pollutants in various systems, serving as output parameters. By evaluating the model's performance under different input conditions, molecular descriptors with high relevance to the output parameters were identified and retained. Ultimately, the most influential input parameters in each model were analyzed using the Shapley Additive Explanation (SHAP) method, which facilitated the speculation of the reaction mechanism. The findings revealed that, compared to the UV system, the contribution of S1 excited state descriptors and nucleophilic reaction-related descriptors in the VUV system was markedly enhanced, suggesting that UV185 promotes the transition of pollutants to a more reactive S1 state, thereby accelerating their degradation and mineralization through enhanced photolysis and nucleophilic reaction pathways.

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• Enhancement Mechanism of Biomass Fbire on Filter Cake Formation for Slurry Shield Tunnelling in Sandy Ground

  XU TAO, SHI JINQUAN, DING ZHI

  Abstract: (192) HTML (0) PDF (0.00 ByteKB) (0)

  In the highly permeable soil, pure bentonite slurry is hard to form a filter cake at the tunnel face during slurry shield tunnelling. The viscosity of polymer modified slurry is too high and it may pollute the environment. The enhancement mechanism of biomass straw fiber on the filter cake formation for bentonkte slurry during slurry shield tunnelling in saturated sandy soil was introduced. The infiltration process of slurry in saturated sandy soil was investigated using column infiltration test. The filtration loss, filter cake formation and effective pressure transfer were analysed. The effects of biomass fiber content on filter cake formation and effective pressure transfer were discussed. The results show that: (1) the viscosity of biomass fibre enhanced slurry is low, the stability of suspended particles is high and the density of biomass fibre enhanced slurry is low; (2) the ability to form a filter cake of the biomass fibre enhanced slurry is greatly improved, which can reduce the use of bentonite; (3) the infiltration model well predicts the infiltration process of biomass fiber enhanced slurry.

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• Study of the Mechanical Behavior of the Cable-Saddle System of the Spatial Main Cable Suspension Bridge

  TAN Zhengjun, Wang Lu, Gu Song, Shen Ruili, Bai Lunhua

  Abstract: (171) HTML (0) PDF (0.00 ByteKB) (0)

  To clarify the mechanical behavior of the cable saddle system in spatial cable-stayed suspension bridges, based on the structural characteristics of two types of spatial cable saddles, a theory of lateral force synthesis was derived, and the force patterns of the two types of spatial cable saddles were demonstrated. Taking a certain spatial cable-stayed suspension bridge as an example, a slice numerical model was established using ABAQUS to study the internal wire force characteristics, lateral pressure distribution patterns, and friction resistance composition of the two types of spatial cable saddles. The results show that the force pattern of the inclined plane saddle is the same as that of the plane saddle, and the lateral forces between the saddles are all caused by radial forces pointing to the center of the circle; for the spatial curved cable saddle, the radial force is approximately equal to the vector sum of the radial forces produced by vertical and horizontal bending, and in the spatial curved cable saddle, the outer pressure is greater than the inner pressure; the internal stress of the saddle groove is mainly concentrated in the local contact area, which is consistent with the classical Hertz theory; the force chain between the upper and lower layers of wires forms a diamond shape, with the force value gradually increasing with depth, but there is a sharp drop at the bottom layer; in the inclined plane saddle, the saddle base provides 86.4% of the friction resistance, and the saddle side only accounts for 13.6%; in contrast, the base of the spatial curved cable saddle provides 86.62%, and the saddle side provides 13.38%. In both types of spatial cable saddles, the contribution of the saddle base to friction resistance is much greater than that of the side.

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• Post-earthquake functional state assessment of railway simply supported bridge based on fault tree model

  weikai, huzhenchen, luxiaoluo, tangxiaomin

  Abstract: (79) HTML (0) PDF (0.00 ByteKB) (0)

  To reasonably evaluate the post-earthquake traffic function of railway bridges, a method based on the fault tree model was proposed for assessing the functional state of railway simply supported bridges. First, a fault tree model was developed with the post-earthquake functional state as the top event. Then, seven kinds of seismic failure modes were defined according to the basic events of the fault tree. A post-earthquake functional state assessment process for bridges was established with different seismic failure modes. Finally, the proposed method was applied to analyze typical railway simply supported bridges with the span length of 32 m in southwest China. The results indicate that the primary seismic failure modes of bridges involve combined damage to bearing and other components. With the increase of earthquake level, the post-earthquake traffic function of railway bridge decreases significantly. The failure mode involving combined damage of the rail and other components is the key factor contributing to the decline of the post-earthquake traffic function of railway bridges.

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• Study of Large-scale direct shear test on shear characteristics for MICP-treated soil using biostimulation approach

  LIU Aqiang, XIE Liuyang, XIAO Yang, HUANG Xiaoli, GAO Yiming, GOU Ruinan, CUI Hao

  Abstract: (207) HTML (0) PDF (0.00 ByteKB) (0)

  Microbially induced calcium carbonate precipitation is a new and sustainable technology, which includes bioaugmentation and biostimulation approaches. However, the existing related research is mostly limited to bioaugmentation approach, and there is relatively little research on biostimulation approach, especially large-scale experiments. In this study, the surface soil along Jialing River in Chongqing is taken as the research object, and the influence of different reinforcement degrees on the shear characteristics of large-scale samples is explored based on biostimulation approach. In addition, the distribution of calcium carbonate content in different directions was also determined. The results show that the stress-strain relationship of the specimen before and after strengthening has changed from strain hardening to brittle fracture and strain softening. In terms of dilatancy, the specimen shows a phenomenon of shear shrinkage before reinforcement, while the specimen shows a slight shear shrinkage first and then a phenomenon of shear expansion after reinforcement. After reinforcement, the shear strength of the specimen has been greatly improved. The calcium carbonate content in the sample decreases with the increase of the distance from the top surface of the sample, and the calcium carbonate content in the sample presents a distribution pattern of high in periphery part and low in middle part. The results of this study can provide reference for the application of biostimulation approach in field tests.

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• Analysis method for bending capacity of core-filled composite pipe pile

  YU Xuekui, XIAO Shiguo, WU Bing, LIANG Yao

  Abstract: (208) HTML (0) PDF (0.00 ByteKB) (0)

  The core-filled composite pipe pile is composed of the prestressed high-intensity concrete pipe pile (PHC pile) and ordinary reinforced concrete inside it, which can be helpful to enhance the bending resistance of the pipe pile. For the new composite pile, the calculation formula of the total bending capacity is derived according to static equilibrium conditions of the pile cross-section. Based on the strain difference at the interface between the inner circular and outer ring areas of the pile, the equivalent rectangular stress diagram coefficients in the current specification suitable for rectangular cross-section are improved. So, the computation method of the stress diagram coefficients suitable for the composite pile with circular cross-section are established. The research results show that the results obtained using the proposed theoretical formula agree well with the tests. The pile bending capacity is obviously influenced by the inner reinforcement ratio and tension stress on the prestressed reinforcements. The bending capacity increases nonlinearly with the reinforcement ratio and decreases linearly with the increase of the tension stress. The sensitivity of the bending capacity to main factors follows the order: outer diameter > outer reinforcement ratio >ring thickness > inner reinforcement ratio > tension stress. The core filling can improve the pile bending capacity by 26% and 68% under the inner reinforcement ratio 1% and 3%, respectively. The reason for reinforcing effect of core filling is that the filling can strengthen the limit state and reduce the height of neutral axis on the cross-section, which leads to the significant increase of the bending resistance ratio of the outer ring up to 73%~83%.

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• Calculation method for shear bearing capacity of double T-shaped steel-concrete composite beams

  CHEN Jianbing, TIAN Zhuangyan, LIU Cong, LI Xiang

  Abstract: (196) HTML (0) PDF (0.00 ByteKB) (0)

  In order to investigate the shear resistance performance of double-T-shaped steel-concrete composite beams (DTSCB), three DTSCB specimens were designed and manufactured with concrete slab width and steel plate thickness as parameters, based on the test results of shear-mid-span deflection curve, shear-relative slip curve and strain distribution, The influence of structural parameters on the bearing capacity and deformation capacity of the composite beam was studied. An ABAQUS finite element model was established and validated by comparing with the experimental results to verify the accuracy of the model. The influence of different shear span ratios on the shear resistance of the steel beam, concrete slab, and wing plate with different structural parameters was simulated, and an expression for shear resistance was established. The results show that the limit shear span ratios for diagonal compression failure, shear failure, and bending failure of the composite beam are 1 and 3, respectively. When the shear span ratio is 1-3, the steel plate takes up about 70% of the shear resistance. The accuracy of the shear resistance calculation formula established is higher than that of the current code.

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• Image segmentation approach for surface rust of existing steel structures based on improved DeepLabV3+

  MENG Qingcheng, ZHANG Fa, XIONG Shuang, QI Xin

  Abstract: (204) HTML (0) PDF (0.00 ByteKB) (0)

  Surface corrosion constitutes a prevalent defect form in steel structures, which can undermine the section of components and deteriorate their mechanical properties. Thus, it is imperative to monitor and assess the corrosion damage of steel structures. A lightweight semantic segmentation model for rust images, based on HL-DeepLabV3+, has been proposed to address the challenges of reading errors, texture misjudgments, and color discrepancies caused by visual fatigue during manual inspections. This model aims to improve segmentation accuracy while reducing the parameter count associated with traditional deep learning networks used in rust recognition. Firstly, the coding portion of the backbone network was replaced with a lightweight MobileNetV3 network to minimize the number of model parameters. Secondly, the strip pool module and pyramid pool module were incorporated into the void space pyramid pool module, enabling the network to capture the long-range dependence of isolated rust regions and eliminate the interference in the background region. Finally, the attention mechanism was introduced to make the network focus more on the pixel region that plays a decisive role in rust classification and enhance the feature expression ability of rust. The test results indicate that: Compared with the original model, the size of the HL-DeepLabV3+ model is reduced by 66.73%, and the Accuracy, mIoU, MPA, and F1 scores are increased by 2.54%, 10.11%, 6.79%, and 6.15% respectively. Moreover, the effect is superior to the classical UNet, FCN, SegNet, and DeepLabV3+ semantic segmentation models. This not only realizes the lightweight of the model but also enhances the segmentation accuracy of rust damage.

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• Analysis of Lateral Load Bearing Performance of Pile Foundations Considering Pile Installation and Consolidation Effects

  liuwuhao, zhangfujin, lihui, caoxue, jingqingxin, dongjunjie, yijiangtao

  Abstract: (182) HTML (0) PDF (0.00 ByteKB) (0)

  In ocean engineering, large-diameter steel pipe piles are commonly used as foundations, and they are often installed using either hammer driving or static pressing methods.In cohesive soil foundations, the soil displacement and heave caused by the pile driving effect weaken the shear strength of the surrounding soil and generate excess pore pressure. After pile installation, the excess pore pressure around the pile gradually dissipates, and the soil undergoes reconsolidation, with its strength and stress state gradually recovering. However, existing studies and design codes rarely consider the effects of pile driving and consolidation on the bearing performance of horizontally loaded piles.This study uses a self-developed multi-stage Euler-Lagrange method to continuously and comprehensively simulate three distinct stages of static-pressed pile installation: pile penetration, consolidation strengthening, and horizontal loading. The research delves into the pile-soil interaction mechanism, the soil strength recovery mechanism between piles, the ultimate resistance of the soil around the pile, and the variation of the P-y curve. The results show that while the consolidation effect does not change the soil deformation mechanism, it significantly increases the ultimate soil resistance along the pile side. Furthermore, the study clearly identifies and quantifies the effects of pile driving and consolidation on the bearing capacity of horizontally loaded piles, establishing a model for the growth ratio of ultimate soil resistance with depth, and proposing a P-y curve that incorporates both pile driving and consolidation effects. The research findings have significant theoretical value and practical implications for optimizing the calculation methods for the static bearing capacity of marine pile foundations.

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• Analysis of Vibration Propagation and Influencing Parameters in Dynamic Compaction of Miscellaneous Fill Slope

  Zhu Jianmin, Dong Baozhi, Yu Yongtang, Zheng Jianguo, Wen Yukun

  Abstract: (293) HTML (0) PDF (0.00 ByteKB) (0)

  The influence of three independent factors, i.e.vibration source distance, tamping energy and tamping settlement, on the vibration velocity under the energy levels of 4000kN · m, 12000kN · m and 25000kN · m was compared and analyzed in the miscellaneous fill slope and flat site. On this basis, the Bp neural network and Sobol sensitivity analysis method were used to analyze the influence of the above three factors on the vibration velocity. The results indicate that in slope sites, vibration velocity follows a negative exponential relationship from the slope’s shoulder to its base. An "energy concentration" effect is observed at the slope's shoulder, where the vibration velocity is higher than that of flat sites at the same source distance. In miscellaneous fill slopes, vibration velocity mostly ranges between 4 and 25 mm/s, and though it also follows a negative exponential relationship with impact energy, the effect of energy on vibration velocity is limited. As tamping settlement increases, vibration velocity initially rises rapidly, then slows, eventually stabilizing. After reaching a "concave" inflection point on the cumulative tamping curve, the velocity increases or the growth rate accelerates; beyond a "convex" inflection point, the velocity decreases or the growth rate slows. Sensitivity analysis shows that tamping settlement has the greatest influence on vibration velocity, being 1.55 times more significant than source distance and 5.93 times more significant than tamping energy. Reducing tamping settlement is the most effective way to lower vibration, followed by increasing source distance, with tamping energy having the smallest effect.

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• Effect of partial leakage during deep excavation in water-rich sandy strata on retaining wall deformation and ground settlement

  QIU Mingming, Li Xiaomin, ZHAO Haifeng, DUAN Junyi, Yang Guolin

  Abstract: (169) HTML (0) PDF (0.00 ByteKB) (0)

  The stable and controllable deformation of deep foundation pit in water-rich sandy strata was the basic guarantee of underground engineering construction safety. Aiming at the leakage disaster of deep foundation pit in water-rich sandy strata, this paper takes the leakage incidents of launch shaft pit of subway station as the research background, summarizes and analyzes the development process and accident causes of water and sand leakage disaster through field investigation and survey data review, the characteristics of horizontal displacement of retaining wall, ground settlement behind wall and change of groundwater level outside the pit during partial leakage were systematically studied, and the effect rules of partial leakage on the deformation behavior of foundation pit were revealed by numerical simulation method. The results of research shows that the horizontal displacement of the retaining wall increases significantly due to partial leakage, and the maximum horizontal displacement of retaining wall after leakage is 1.29 to 1.47 times that before leakage. The ground settlement trough of sensitive zone deepens and widens due to partial leakage, and the maximum ground settlement after leakage is 1.16 to 2.67 times of that before leakage. The characteristics of "jump" fluctuation of groundwater level can be used as an important criterion for the precursor of leakage disaster in foundation pit. The combined treatment measures of grouting and high pressure rotating spouting pile can effectively deal with the problem of leakage disaster control of foundation pit in water-rich sandy strata.

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• Study on the Mechanical Characteristics of Polyurethane Materials for Emergency Road Recovery under Cyclic Loading

  XU Xiaoliang, Liao Wenjie, XU jiapeng, LI Bei, TAN Yizhong

  Abstract: (113) HTML (0) PDF (0.00 ByteKB) (0)

  Polyurethane foam material, with its rapid expansion, high strength, lightweight, and water-repellent characteristics, has significant engineering value in temporary repair works such as emergency road clearance after water damage. To study the mechanical characteristics of polyurethane materials for subgrade under cyclic loading, axial cyclic loading and unloading compression test , and tangential cyclic shear test were carried out on polyurethane samples containing interface, and the change rule of stress-strain law and macro and micro damage characteristics of polyurethane samples wereanalyzed under different loading frequencies and loading ranges. The results show that: The strain of polyurethane samples increases and then decreases with the frequency of axial loading, and continuously increases with the upper limit of axial stress loading (up to 7%~8%); the maximum strain increment induced by axial stress loading is four times the corresponding value for the loading frequency, which has a more significant effect on the sample strain; under axial cyclic loading and unloading, the sample is mainly subjected to compression-shear damage along the cemented surface and tensile-shear damage along the vertical fissure-cohesive surface, the increase in the loading range of the tangential force causes a significant increase in the deformation of sample (up to 5%~6%), and eventually compression-shear damage along the cemented surface occurs; increase a certain amount of axial force (should not exceed 90% of the uniaxial compressive strength) can be better compaction of polyurethane materials, which can improve its shear performance, in engineering applications, it is advisable to avoid placing polyurethane materials in a cyclic shear stress state when the axial force is small or there is no loading.

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• Unloading creep model of variable coefficient uncertain fractional rock considering aging damage

  WANG Ping, YANG Jin, WANG Jing-yong, JI Feng

  Abstract: (112) HTML (0) PDF (0.00 ByteKB) (0)

  The traditional creep model is difficult to characterize the complete creep behavior of rock. In order to reveal the unloading creep mechanical properties of granite, the high-potassium calc-alkaline I-type granite of a pumped storage power station was taken as the research object, and the triaxial unloading creep test under the constant axial pressure unloading confining pressure stress path was carried out. The creep strain characteristics and rock damage evolution law of granite during unloading process were analyzed. Based on the fractional calculus theory, a variable coefficient non-definite fractional unloading creep damage model which can accurately describe the whole process of granite creep was constructed and extended to three-dimensional stress state. The results show that in the triaxial unloading creep test, with the decrease of confining pressure, the total axial creep of each stage of the sample increases continuously, and the total axial strain is dominated by instantaneous elastic strain. The rock exhibits strain softening characteristics and is brittle failure when destroyed. The parameter identification and fitting of the triaxial unloading creep test data were carried out by using the variable coefficient unsteady fractional unloading creep damage model. The fitting results show that the model can better describe the creep damage evolution characteristics of the high potassium calc-alkaline I-type granite in Yanshan period. The research results can provide experimental basis and theoretical guidance for the long-term stability research and support scheme design of underground caverns in similar areas.

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• Experimental study of transparent soil modelling of pipe-soil interaction during uplift of rectangular pipe gallery

  wuyuhan, qigeping, tangyuteng

  Abstract: (92) HTML (0) PDF (0.00 ByteKB) (0)

  As a type of non-circular section corridor in the construction of underground comprehensive pipe corridors, the uplift process of rectangular pipe corridors has a more complex impact on the surrounding soil compared to traditional circular corridors. However, there is currently limited research on the pipe-soil interaction during the uplift process of rectangular pipe corridors. To address this issue, a transparent soil model test was conducted to study the pipe-soil interaction during the uplift process of rectangular pipe corridors. The focus was on measuring and analyzing the changes in the p-y curves of the rectangular pipe corridors at different densities and burial depths, as well as the displacement field changes of the surrounding soil. The research findings indicate that the p-y curve trends at different burial depths of the rectangular pipe corridor exhibit similar characteristics under varying densities, going through phases of linear increase, peak variation, rapid decline, and gradual decrease. The greater the density and burial depth of the rectangular pipe corridor, the larger the amplitude of change and the maximum bearing capacity. The displacement field changes of the soil at the same burial depth during different stages of the uplift process are similar, with the surrounding soil displacement transitioning from an overall upward movement to localized upward movement at the upper and lower sections of the corridor while the surrounding areas move downward. Additionally, at the same density and burial depth, the angle of the displacement change surface of the soil increases with the height of uplift.

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• Calculation and numerical simulation of pollutant accumulation in the controlled environment by circulating air system

  PAN Wu-xuan, ZHANG Hui-jie, SONG Gao-ju, SONG Chong-fang, LEI Yong-gang, LIU Xiao-zhi

  Abstract: (158) HTML (0) PDF (0.00 ByteKB) (0)

  The circulating air system can make full use of the re-transportation capacity of the air and reduce the total real-time emissions, which has become an important choice for industrial ventilation due to its energy-saving and emission reduction characteristics. However, there is a phenomenon of pollutant accumulation in the controlled environment of the circulating air system, and the research on the precise control of the accumulation of pollutants in the controlled environment and the proportion of circulating air is not perfect. In this study, a real-time calculation method for controlling pollutant accumulation in the environment by circulating air system was developed. Based on the intermittency of pollutant emission in the foundry industry, a method for calculating the proportion of circulating air under different process conditions was proposed, and the proportion range of circulating air was dynamically adjusted. The spatiotemporal distribution of pollutants in a controlled environment was studied by CFD discrete phase model (DPM). The results show that the average error between the simulation results and the theoretical calculated values at different times is within 15%, which is in good agreement. The circulating air system can effectively reduce the fresh air volume and the total real-time emission of the dust removal system; The upper limit of the concentration of pollutants in the environment controlled by the circulating air system is determined by the calculation of the intensity of the pollution source, the proportion of circulating air, and the filtration efficiency of the dust collector. In addition, through the dynamic characteristics of pollutant concentration changes under different circulating air ratios in the controlled environment, it is very important to select the appropriate circulating air ratio, which is very important to reduce the pollutant accumulation in the environment controlled by the circulating air system on the basis of energy saving.

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• Model tests on the load bearing deformation behavior of reinforced subgrades using waste whole tires

  GUO Yukang, JIA Yafei, XIE Mingxing, ZHANG Jun, ZHENG Junjie, ZHENG Yewei

  Abstract: (189) HTML (0) PDF (0.00 ByteKB) (0)

  The large number of waste tires in our country has led to increasingly severe black pollution. Applying waste tires to engineering is one of the ways to dispose of tires. Waste tires have good engineering properties, such as high strength and corrosion resistance. Studying their role in subgrade construction is of great significance for guiding the construction of reinforced subgrades with waste tires. However, existing research mainly focuses on the reuse of tire fragments, and there is insufficient research on the reuse of whole tires. In order to further investigate the connection between tires and the influence of fillers on the whole tire reinforced subgrade, three model tests were conducted to explore the deformation characteristics of waste tire reinforced subgrades. The subgrade top surface displacements, vertical soil pressures, and tire strains under different stress levels were analyzed. The research results indicate that the tire reinforcement layer is conducive to the distribution of additional stress, and as the load increases, the role of the tire reinforcement layer in distributing stress gradually strengthens. Laying geogrids below the tire reinforcement layer effectively increases the overall stiffness of the reinforced zone and reduces subgrade deformations. The combined effects of the tire and geogrid increases the distribution angle of additional stress in the soil near the tire reinforced zone, and geogrids share some loads, reducing tire deformations.

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• Experimental study on the effect of calcium source and treatment rounds on MICP mulching effect of sandy loess

  LI Jialiang, DU Qiang, LIU Xumei, QU Liqiang

  Abstract: (203) HTML (0) PDF (0.00 ByteKB) (0)

  In view of the loose structure of sand loess in the northern Loess Plateau, the cohesion between particles is small, and it is easy to be damaged by rainwater erosion, MICP technology is used for film mulching protection. The effects of calcium source and treatment rounds on the MICP mulching effect of sandy loess were investigated. Three calcium sources of calcium chloride, calcium acetate and calcium lactate were selected to mulch the slope model under four different rounds. The calcium carbonate content, indoor rainfall scouring test and micro-penetration test were carried out on the samples after mulching. The results show that: Different calcium sources have different coating forms. Calcium chloride and calcium acetate mainly strengthen the soil by increasing the cohesion between soil particles, while calcium lactate is more likely to form a hard shell layer on the surface of the soil to protect the soil. The effects of calcium source and treatment rounds on the MICP coating effect of sandy loess are mainly reflected in the content of calcium carbonate and the curing depth. The effects of different calcium sources on film mulching under different treatment rounds were different. When calcium chloride was used as calcium source, the effect of film mulching was better when the treatment was more than 3 rounds, and the effect of film mulching was not obvious when the treatment was more than 5 rounds. Calcium acetate as a calcium source, the effect of film mulching was poor when treated for 1 round. When treated for 3 to 7 rounds, the effect of film mulching increased significantly with the increase of rounds. Calcium lactate as a calcium source, the effect of film mulching was better when treated for 1 round, but the effect was not as good as calcium chloride and calcium acetate when treated for more than 3 rounds. The research results of this paper can provide some reference for the protection of sand loess slope erosion in Ordos area.

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• H-junction Incomplete Mixing Laws and Empirical Models Considering Multiple Factors

  gaojinliang, likunyi, zhangjiawen, dongwenchao, yinxiaoming, zhengxiaoxin

  Abstract: (146) HTML (0) PDF (0.00 ByteKB) (0)

  As an important component of water supply networks, the H-junctions exhibit unclear characteristics of income-flow incomplete mixing. This paper investigates the phenomena and influencing factors of incomplete mixing at H-junctions within water supply networks, intending to improve existing water quality simulation techniques. By combining computational fluid dynamics (CFD) numerical simulations and laboratory experiments, the effects of various factors such as pipe diameter, spacing of tees, and inlet and outlet Reynolds number ratios on incomplete mixing at H-junctions were explored. The findings suggested that while pipe diameter has minimal influence on mixing, spacing of tees and inlet/outlet Reynolds number ratios significantly affect the degree of mixing. Moreover, the experimental results aligned well with CFD simulations, validating their accuracy and providing data for establishing an empirical model for incomplete mixing at H-junctions under different spacings of tees. Ultimately, an empirical model for H-junction incomplete mixing based on the specific spacing of tees conditions was proposed. Selecting appropriate mixing models in practice to enhance the accuracy of water quality simulations in water supply networks was recommended, which is crucial for ensuring water safety and optimizing operational scheduling.

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• Analysis of temperature characteristics of steel-concrete composite beams during hot asphalt paving

  zhangyuping, chuyonghao, jiangjiaping, tangxin, mayugang

  Abstract: (168) HTML (0) PDF (0.00 ByteKB) (0)

  Temperature fluctuations caused by hot asphalt paving on bridge structures represent a transient process that is challenging to monitor precisely. In order to investigate the temperature field of steel-concrete composite beams during asphalt high-temperature paving. By combining field measurements and finite element numerical simulations, the temperature distribution pattern of steel-concrete composite beams under asphalt high-temperature paving was investigated. A predictive formula for vertical temperature differences caused by asphalt high-temperature paving was proposed by utilizing a parameter analysis method. The research results indicated that the influence depth of asphalt high-temperature paving on steel-concrete composite beams mainly occurred within a range of 0.5 m and formed a large vertical temperature gradient. The vertical temperature difference pattern can be approximated by an exponential function, while the horizontal temperature difference pattern can be approximated by a sine function. The maximum vertical temperature difference is mainly influenced by the initial temperature of the beam T0, the thickness of the intermediate layer d, and the temperature of the asphalt mixture Ts. The calculated results from the proposed vertical temperature difference prediction formula are consistent with existing research. Provided a reference for studying the temperature distribution of steel-concrete composite beams during asphalt hot-mix paving.

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• Strength characteristics and environmental effects of red mud-based cementitious material activated with calcium carbide slag-phosphogypsum

  LI Xiang, GUO Rongxin, LIU Zhuo

  Abstract: (402) HTML (0) PDF (0.00 ByteKB) (0)

  The low hydration activity and high heavy metal ion content of red mud restrict its application in the field of building materials, and the preparation of good performance and economic and environmental friendly red mud-based cementitious material to realize the large admixture utilization of red mud is a problem to be solved in the green and efficient application of red mud. Red mud-based environmental cementitious material (RFCG) was prepared by activated red mud and fly ash with calcium carbide slag and phosphogypsum. The effects of calcium carbide-phosphogypsum ratio, calcination temperature of red mud, and sealing high-temperature curing time on the strength law of RFCG were investigated, and XRD, SEM-EDS, and ICP-OES were used to explain the strength law of RFCG from the microscopic mechanism and assess the environmental impact of RFCG. The results showed that OH- provided by calcium carbide slag promoted the reaction and generated C-(A)-S-H and a small amount of N-A-S-H gel, which contributed to the strength development of RFCG; AFt generated by SO42- provided by phosphogypsum enhanced the densification of the matrix by filling the microscopic pores to improve the strength, but the excessive AFt led to the development of microcracks in the matrix, which had an impact on the strength development greater. Calcination treatment enhanced the silica-aluminum ion leaching rate of red mud and attenuated the negative effect of organic matter in red mud, resulting in a substantial increase in the strength of RFCG. Conservation at 60 °C for 24 h effectively improved the early strength of RFCG. The prepared RFCG stabilized heavy metal ions, avoided secondary pollution to a certain extent, and could be applied in engineering fields such as pavement subgrade and mine filling.

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• Effects of sliding bearing wear on the static and dynamic performance of cable-stayed bridges

  Zhou Hong, Li Chong, Yang Dong-Hui, Yuan Jie-Yi, Yi Ting-Hua, Guo Chong-Yuan

  Abstract: (138) HTML (0) PDF (0.00 ByteKB) (0)

  Sliding bearing is a commonly used type of bearing in cable-stayed bridges, which is also one of the important force transmitting components of bridges. Sliding bearing is often worn during operation, resulting in performance degradation. It is of great significance to analyze the influence of sliding bearing performance changes on the overall mechanical properties of cable-stayed bridges. Based on the finite element model of cable-stayed bridge considering bearing wear, this paper analyzes the influence of sliding bearing wear on the static and dynamic performance of cable-stayed bridge. Taking a cable-stayed bridge as an example, the finite element model of cable-stayed bridge considering bearing wear is established, and the change of the static and dynamic performance of the cable-stayed bridge is analyzed when the sliding bearing is worn. It is shown that sliding bearing wear will increase the bridge stiffness, leading to an increase in frequency, especially longitudinal drift and vertical bending modal, increase the girder end axial force significantly and reduce the cumulative bearing displacement. The bearing cannot adapt to the deformation needs of the girder, resulting in a buildup of internal forces in girder and bearing. This can lead to an increased risk of damage and affect the safe operation of the bridge. This study can provide some guiding suggestions for bearing damage identification and bridge maintenance of cable-stayed bridges.

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• Study on the horizontal bearing mechanism of single necking pile with cap

  xuzhijun, ZONG Feilong, GUO Zhaoxiang, WANG Zhengquan, AN Ruijun

  Abstract: (136) HTML (0) PDF (0.00 ByteKB) (0)

  Pile foundation is easy to develop necking during construction and service, which will bring potential safety hazards to the superstructure. Clarifying the characteristic of horizontal bearing capacity for necking pile with cap is important to engineering design and reinforcement repair of pile foundation. Transparent soil made by fused silica sand and pore liquid with the same refractive index is utilized to carry out model experiment and investigate the effect of necking on horizontal bearing capacity of necking pile with cap. The soil deformation around piles were obtained after process the soil particle speckle field assisted with Mat-PIV incremental program. Subsequently, three-dimensional finite element numerical simulation is incorporated to explain the change reason of horizontal bearing capacity induced by necking. Results show that necking will weaken the transfer ability of horizontal load along pile shaft, and drive the deformation of upper pile shaft and soil anti-force on pile side to increase. The horizontal bearing capacity decreases with the increase of necking dimension, or decrease of necking position away from pile top. The pile bending can cause pile cap to develop oblique downward displacement, which will exert vertical pressure on the soil. Subsequently, the strength of the shallow soil is enhanced and the developing friction limit pile deformation, resulting in improving the bearing capacity of the pile.

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• Research on compression characteristics of rubber sand based on transparent soil technology

  Zhou En Quan, Wang Meng, BAI Yuhang, WANG Long

  Abstract: (121) HTML (0) PDF (0.00 ByteKB) (0)

  Using crushed waste rubber tires mixed with sand as a lightweight backfill material in geotechnical engineering is one of the most promising measures to deal with waste tires. In order to study the compressive characteristics of rubber sand, this paper conducted one-dimensional consolidation compression tests on transparent rubber sand to investigate the deformation mechanism of rubber sand and established a characterization model of rubber sand"s compressive characteristics. The results show that the total vertical strain of rubber sand increases with the increase of rubber content, and the plastic strain is greater than the elastic strain. Compared with pure sand, the increment of the compressive deformation of rubber sand mainly comes from the compression deformation of rubber particles themselves and the rolling rearrangement of sand particles caused by the deformation of rubber particles. Based on the compression models of pure sand and rubber, a compressive characteristic characterization model of rubber sand with different rubber content was established, and the model has good applicability. The research results can provide scientific support for the engineering application of rubber sand.

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• Research progress on coupled thermohaline double diffusion in rock and soil

  FAN Zhenghao, ZHANG Bodu, WANG Xinkai, CUI Jingcheng, BaoTing

  Abstract: (103) HTML (0) PDF (0.00 ByteKB) (0)

  Engineering challenges related to saline soil roadbed disaster prevention and mitigation, land resources, protection of stone relics, geothermal development, carbon dioxide geological storage, and nuclear waste disposal recently have become increasingly prominent. A critical factor in addressing these issues is understanding the coupling theory of thermal and salt diffusion in rock and soil. This theory is essential for preventing soil salinization, preventing diseases of infrastructure and stone relics, enhancing heat extraction efficiency, improving sealing effectiveness, and reducing groundwater pollution. This paper first summarizes the research methods related to thermohaline double diffusion coupling in both soil and rock. The paper then systematically reviews typical theoretical models in this field. Building on this foundation, the paper explores the future research directions for thermohaline double diffusion coupling theory, particularly in the context of modern energy demands and environmental protection needs. Comparative analyses of different thermohaline diffusion coupling models are also presented. Finally, the importance of studying the coupling theory of thermohaline diffusion in rock fissures is highlighted, especially in relation to critical engineering problems such as CO2 storage in saline aquifers, geothermal exploitation in salt zones, and nuclear waste disposal in salt caverns. Additionally, the paper outlines future research prospects for the coupling of thermohaline diffusion with mechanical effects in the context of soil and rock conservation, particularly for the preservation of cultural relics.

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• Identification of cable tension based on physics-informed neural network

  XU Hao, SHAN Deshan, WU Kang, YU Zhongru

  Abstract: (271) HTML (0) PDF (0.00 ByteKB) (0)

  Accurate identification of cable tension has important practical significance, but the vibration-based tension estimation methods has the problem of complex and diverse calculation formulas in application. Based on this, this paper introduces the physics-informed neural network (PINN) into the field of cable tension identification, and proposes a method of cable tension identification based on physics-informed neural network. In this method, the loss term of string vibration equation representing the cable tension is introduced into the loss function of neural network, and the network is trained by using the dynamic displacement response of the cable. The cable tension can be identified by minimizing the loss function. Based on the finite test data of numerical simulation examples and indoor test model, the proposed method is used to realize the accurate identification of cable tension. The results show that the identification error of the proposed method is less than 3% in all the cable tension identification problems set in this paper. This result proves that this method has high identification accuracy, strong reliability and good scalability, and is suitable for the identification of cable tension in practical engineering.

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• Model experimental study on bearing characteristics of integral wall Geosynthetic Reinforced soil abutment

  XU Haozhe, CAI Xiaoguang, ZHU Chen, Li Sihan, ZHANG Li

  Abstract: (65) HTML (0) PDF (0.00 ByteKB) (0)

  The geosynthetic-reinforced soil integral bridge, as a novel type of abutment, demonstrates significant application value in small-span bridge and culvert engineering. Currently, research on its operational mechanisms is limited, particularly regarding the bearing capacity characteristics of abutments, which have been seldom studied. This paper presents a static load test of a geosynthetic-reinforced soil integral bridge model based on the Z(v)erovinci bridge in northern Slovenia. The analysis includes the settlement at the top of the abutment, the displacement of the facing panel, the horizontal displacement of the soil behind the facing panel, the pattern of reinforcement strain, and the nature of the potential fracture surface. The measured tensile force of the abutment reinforcement is compared with the calculated values recommended by three codes. The results indicate that under maximum load, the top settlement of the abutment does not exceed the usage and strength limits recommended by the code. The horizontal displacement of the middle panel of the abutment is the largest, and the maximum soil displacement behind the front and wing wall panels occurs at the top of the model. Under specific loading conditions, the maximum reinforcement strain of the longitudinal bridge reinforcement remains below the normative value, and the calculated stiffness values align well with the measured maximum tensile force of the reinforcement.

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• Gradient angle discrimination and reliability analysis of pile foundation drilling in complex karst areas

  mouyunzhen, zhangyong, Zhang wengang, Huang leyuan, Liuzhiwei, Zhangbenyi, Xiao Peng, Chuliang

  Abstract: (113) HTML (0) PDF (0.00 ByteKB) (0)

  In the construction of underground rock projects, complex geological conditions are often encountered, especially special conditions such as karst caves and faults, which bring great challenges to pile foundation construction. To study the accuracy of pile foundation drilling data under complex karst geology, this paper takes the pile foundation project in Yinshawan Karst Area, Jiujiang, Jiangxi as the basis, and proposes the spatial characteristics of cave gradient angle based on the drilling data of the whole site, and uses the JC method to analyze the reliability of drilling data. The results show that the cave rate of the boreholes in this karst pile foundation construction site exceeds 50%, and the karst is extremely developed. According to the four spatial distribution modes of cave gradient angle, the drilling data with higher accuracy of cave information are preferentially screened out. The JC method is used to analyze the reliability of the data with lower accuracy, and it is found that the gradient angles calculated with small, medium and large cave depths as reference values all obey the normal distribution, and the accuracy of drilling hole identification of cave characteristics increases significantly with the increase of cave depth. Finally, on the basis of controlling the supplementary drilling rate, a data screening and optimization strategy is proposed. Through the comparison of quantitative indicators, it is verified that the supplementary drilling rate controlled at about 5% can significantly improve the reliability of drilling results

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• Study on dynamic response characteristics model test of geotechnical reinforced embankment under train loads in inclined stratum

  Ding Xuanming, Ren Jiyu, ouqiang, Zhao Jinqiao

  Abstract: (140) HTML (0) PDF (0.00 ByteKB) (0)

  It is often easy to cause overall or local damage of railway embankment in mountainous areas due to the complex topographic and geological conditions when constructing high-speed railway. With the development of geotechnically reinforced technology, more and more mountain railway embankments adopt geosynthetics reinforcement to solve the deformation damage of embankments, however, the dynamic response characteristics and deformation law of geotechnical reinforcement under inclined stratum conditions are still ambiguity. Therefore, based on the model comparison test between railway embankment with inclined bedrock reinforcement and without inclined bedrock reinforcement, this paper carries out the research on the dynamic response characteristics of geotechnically reinforced railway embankment under inclined stratum conditions. And a comparative analysis on the changing rules of the vertical displacement, acceleration, dynamic soil pressure, and geogrid strains of geotechnically reinforced railway embankment was conducted. It aimed to investigate the dynamic response characteristics of geotechnically reinforced railway embankment under inclined stratum. The results showed that the vertical peak displacement of the inclined bedrock embankment is slightly larger than that of the uninclined bedrock embankment, and the vertical peak displacements of both cases decrease with the increase of loading frequency. The vertical peak acceleration and vertical peak dynamic soil pressure of the inclined bedrock embankment are obviously larger than those of the uninclined bedrock embankment, and both of them increase with the increase of loading frequency and decrease with the increase of burial depth. When the depth of burial is the same, the soil below the loading center of the embankment has the largest peak vertical acceleration and peak dynamic soil pressure, followed by the side away from the bedrock, and the side near the bedrock has the smallest. The peak micro-strain of the grids of the embankment all decreased with increasing depth of embedment of the grids, and the two layers of grids near the top of the embankment decayed less, whereas the peak micro-strain of the grids of the inclined bedrock-reinforced embankment was about twice as much as that of the uninclined bedrock-reinforced embankment at the same loading frequency.

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• Model test of mechanical response process of buried polyethylene pipeline under the stacking load

  LIN Fangze, LU Jianguo

  Abstract: (181) HTML (0) PDF (0.00 ByteKB) (0)

  In this study, a typical buried PE pipe model test under the action of stacking load was carried out by means of an independently designed pipeline test system. The results show that the accumulation load has a significant effect on the mechanical properties of the pipeline. The peak of the strain around the pipe appears below the load and decreases towards both ends of the pipe. The strains on the cross section of the pipeline develops symmetrically under vertical stress. The strain of the pipeline is non-linear, and it goes through two stages of slow and fast growth, with the increase rates of 40% and 76.3%, respectively. The interaction between the pipeline and soils results in different stress states in the same axial direction while the pipeline generally shows axial stretching. Simultaneously, the elastic recovery of the pipeline is inhibited under the pipe-soil interaction, and the pipeline presents a beam-type bending and a flex-like shape. Additionally, both ends of the pipeline are constrained and the soil resistance produces a small degree of reverse displacement. The overlying soil sinks or rises with the deformation of the pipeline, and the additional accumulation load gradually diffuses to the deep layer and dissipates.

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• Gamma Generalized Linear Model for Natural Carbonization Depth Prediction of Concrete

  MA Qian, CHEN Mengcheng, FANG Wei, XIE Lie, HUANG Hong, XV Kaicheng, GUO Liqin

  Abstract: (394) HTML (0) PDF (0.00 ByteKB) (0)

  Concrete carbonization is one of the major reasons for the degradation of reinforced concrete (RC) structures, which reduces their durability, serviceability and safety. Therefore, the reasonable prediction model of concrete carbonation depth can provide a reference for durability evaluation and service life prediction of RC structures and be of great significance. Firstly, 273 sets of measurements of China natural carbonation depth of concrete from publications in China and foreign journals were collected and depicted with the histogram. According to the Kolmogorov-Smirnov goodness of fit test, it was found that the measurements of carbonization depth follows Gamma probability distribution. Subsequently, in terms of the Chinese national standard GB-T51355-2019 model and the international standard CEB-FIP-2010 fib-model along with the natural environment of RC structure concrete carbonization, the main factors affecting the process of concrete carbonization were analyzed, concluding that concrete aging compressive strength, relative humidity, temperature, curing mechanism, CO₂ concentration, shelter and rain are the main influencing factors. Secondly, due to the fact that the natural carbonization process of RC concrete is a random, monotonic and increasing one, the Gamma stochastic process model was thus used to characterize it. Using the model and the above main influencing factors as explanatory variables, a new Gamma generalized linear regression model for the natural carbonization depth prediction of concrete was established. Finally, the natural carbonation depth of real RC structure concrete was calculated by the proposed model, and compared with the measured data as well as the predictions by the Chinese standard model and the international fib-model. It was shown that the proposed model has better accuracy in predicting carbonation depth of RC structural concrete than the existing national and international standard models do, and can be used as a potential surrogate model.

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• One-dimensional Consolidation Characteristics of Saturated Soils Considering the Memory Effect of the Seepage process

  Tao ZENG, FENG Tao, CHEN Ya-bo, YU Yong-tang, YAO Yao

  Abstract: (214) HTML (0) PDF (0.00 ByteKB) (0)

  The long-term seepage characteristics of fluid flow in saturated soil are of significant importance. The Riemann-Liouville (R-L) fractional derivative was adopted to modify classical Darcy"s law (hereinafter referred to as modified seepage model) to describe the evolution of soils’ permeability during the long-term seepage process. Data fitting of experimental results given in published literature show that the modified seepage model could more accurately describe the nonlinear evolution of fluid velocity with time. Moreover, the anomalous permeability coefficient value obtained with the modified seepage model is found to be reasonable. The R-L fractional diffusion equation was derived by integrating the modified seepage model into the one-dimensional Biot consolidation model. The explicit (time domain)-implicit (space domain) difference method was employed to discretized the above equation, and the correctness of the algorithm was verified through numerical example. On this basis, the influence of the modified seepage model parameters on the one-dimensional consolidation process of saturated soil was investigated. The results show that fractional order reflects the degree of soil permeability decay. The higher the fractional order, the lower the soil permeability, which leads to a further decrease in the consolidation rate; Additionally, similar to the permeability coefficient , an increase in the abnormal permeability coefficient also accelerates the consolidation rate of saturated soils. However, it is the permeability coefficient plays the dominant role.

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• Constitutive modeling of over-consolidated soil based on the state-hardening rule

  Li Haichao, Li Xinyu, Zhang Yuhui, Li Tao, He Zuoyue

  Abstract: (184) HTML (0) PDF (0.00 ByteKB) (0)

  The strength and deformation behaviours of overconsolidated clay are influenced by various factors such as the initial void ratio, stress path, and preconsolidated stress. To describe the state dependency of overconsolidated clay, this paper introduces the density state parameter and stress state parameter, which help characterize the differences in void ratios between current and dyadic state points. These parameters are utilized in a new constitutive model for overconsolidated soil, which also includes a new state-dependent hardening rule to describe the evolution of the subloading surface where the current state point is located. The proposed model features a single-yield surface to simplify the formula, and its material parameters can be calibrated using conventional laboratory tests. The model's predictions are compared with triaxial test data of various types of clays under drained and undrained conditions, showing good agreement. The comparison results indicate that the evolution of the stress-state parameter and density-state parameter is influenced by the preconsolidated pressure, which reduces to zero once the clay sample reaches the final critical state. Additionally, in preconsolidated clay, the stress-strain curve of the soil sample demonstrates noticeable softening characteristics during the drained shear process, initially resulting in a volume decrease followed by an increase. In the undrained shear process, negative pore water pressure is generated.

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• Analysis of the effects of different influencing factors on the phenomenon of seepage erosion under vibration

  ZHANG Dongmei, CHEN Huihao, CHEN Sirui, XIE Xiaochuang

  Abstract: (163) HTML (0) PDF (0.00 ByteKB) (0)

  The development process of seepage erosion is complex, influenced by numerous factors, and disasters triggered by seepage erosion are frequent, posing serious threats to structural safety. To study the effects of various factors on seepage erosion under vibration, this paper employs a CFD-DEM coupled analysis method. Seepage erosion experiments on eight groups of gap-graded sand samples were conducted to investigate the effects of fine particle content, confining pressure, and hydraulic gradient on the seepage erosion process under vibration. The micro-responses of the gap-graded sand samples were analyzed based on the fine particle loss ratio and axial deformation. The results show that under vibration, the fine particle loss ratio is higher, and axial deformation is more significant. The vibration has an aggravating effect on the seepage erosion, with the greatest effect on the upper layer particles, while the middle layer particles are least affected. Higher fine particle content leads to greater fine particle loss and longer stabilization time, making it a significant factor affecting axial deformation. Greater confining pressure results in more fine particle loss and axial deformation, with confining pressure having a mitigating effect on vibration. In the development stage of seepage erosion, a larger hydraulic gradient results in a higher fine particle loss ratio, with the hydraulic gradient having the least effect on axial deformation.

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• Explainable machine learning model for strength component correlation analysis of high-performance concrete

  jinxinbin, liyan, Wang Zhiguo, Zhao Yuxin, Liang Wenbiao

  Abstract: (157) HTML (0) PDF (0.00 ByteKB) (0)

  The strength of high-performance concrete demonstrates a intricate relationship with its components. Traditional black box models lack interpretability. As a result, they fail to reveal the actual dependency between concrete strength and its components. Using a large sample dataset of high-performance concrete, Machine Learning Models are constructed and optimized with the Hyperopt algorithm. The models are integrated with SHAP explanation and feature dependency algorithms. A visual representation of the nonlinear relationship between the strength of high-strength concrete and its components is calculated. Additionally, the interaction and coupling effects between multiple components are examined. The results indicate: Hyperopt-Extreme Gradient Boosting Model is a Trusted Machine Learning Model with high accuracy and robustness. Among the eight components(factors), age, cement, water and slag play a key controlling role in compressive strength, and their relationship with compressive strength satisfies exponential function, power function, Gaussian function, and exponential function. At the same time, there is a significant interactive coupling effect between the four key factors. The research results can provide theoretical reference for the composite design of high-strength concrete and key factor control.

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• A COMPUTATIONAL METHOD FOR ESTIMATION OF ULTIMATE STRENGTH LOSS OF THE CORRODED STEEL COLUMN UNDER AXIAL COMPRESSION

  SangXiaohan, Yang Xia, Li Yang, Chen Lin, Kong Qingzhao

  Abstract: (86) HTML (0) PDF (0.00 ByteKB) (0)

  In this paper, axial compression tests were firstly performed on Q345 grade H-shaped steel columns. Based on systematic theoretical deduction, a computational method was then presented to evaluate the ultimate strength loss of the pitted steel column with H-section under axial compression. The detailed formulas were calibrated by numerical simulations, and the random pitting size and locations were both considered. The influence of a single pit on the column strength loss was firstly investigated, and the contribution function of a single pit was established. Then the interaction effects between pits were investigated by considering the relative size, distance, and angle of the pits, reflected by the interaction coefficient. A family of finite element models with consideration of the randomness of corrosion pits were built to validate the feasibility of the proposed computational method.

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• Adsorption Mechanism of Cu (II) and Zn (II) on Alkaline Silica-Enriched Biochar Composites

  Huangjunfeng, Yu Jin, Luo Jinzhi, Cai Yanyan, Yan Jianhui

  Abstract: (251) HTML (0) PDF (0.00 ByteKB) (0)

  Heavy metal contamination stemming from industrial waste is an increasingly grave issue with extensive repercussions for human health and the ecological environment. Biochar demonstrates significant potential in remedying heavy metal pollution; however, the effectiveness of raw biochar is constrained under low pH and high heavy metal concentrations. To address this challenge effectively, this study utilized dragon fruit peels as precursors to produce biochar through pyrolysis at 500 °C for 2 hours. An efficient green adsorbent, termed GBMSs (green biochar-metakaolin-sodium silicate), was developed. Response surface methodology (RSM) tests revealed that GBMSs exhibited exceptional adsorption performance for zinc, achieving up to 67.37 mg/L at pH=2. Kinetic and isothermal adsorption studies indicated that the adsorption process of GBMSs on Cu and Zn closely followed the Langmuir model and the pseudo-second-order kinetic equation, suggesting surface adsorption of a homogeneous monomolecular layer with a rapid adsorption rate that increased with rising pH. In-depth analysis using XRD and SEM-EDS techniques identified chemisorption as the primary adsorption mechanism, with ion exchange, surface complexation, and co-precipitation playing significant roles. These findings confirm that GBMSs, as an environmentally friendly and efficient adsorbent, holds considerable promise for the treatment of heavy metal pollution.

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• Experimental study on transparent soil model of reservoir landslides under different rates of water level fluctuation

  Wang Yucheng, Fang Xiangwei, Wang Luqi, Liang Hao, Ye Yanwei, Chen Chao, Xiong Peixi

  Abstract: (137) HTML (0) PDF (0.00 ByteKB) (0)

  During normal operation of the Three Gorges Reservoir, the water level will experience periodic fluctuations, and the rate of water level rise and fall has a significant impact on the stability of the reservoir landslides. Considering the Wushan Tapin H1 landslide in the reservoir area as a prototype, a transparent soil model testing system for reservoir landslides has been designed. This system includes a transparent soil landslide model box, a water level fluctuation system, and a computer image acquisition system. The tests were carried out at different rates of water level rise and fall, and the deformation data of the transparent soil landslide were obtained by using the particle image velocimetry technology over the research profile. The deformation characteristics and evolutionary pattern of the landslide were analysed. The results indicate that during water level rise, landslide deformation progresses from the front to the rear, while during water level fall, the deformation progresses from back to front, with greater deformation caused by water level fall. As the rate of water level fluctuation increases, the dynamic water pressure effect within the landslide and the groundwater level lag effect become more pronounced, resulting in increased deformation and more evident deformation characteristics of the landslide. The surface displacement variation curve of the landslide shows a step-like progression, with horizontal displacement increasing significantly more than vertical displacement. An increased rate of water level fluctuation results in greater landslide displacement during intervals when the water level remains unchanged, indicating a decrease in landslide stability.

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• State-of-the-art review of dangerous rocks stability under the influence of water level fluctuations in the Three Gorges Reservoir area

  Lvyuxiang

  Abstract: (206) HTML (0) PDF (0.00 ByteKB) (0)

  The dangerous rock in the Three Gorges reservoir area possesses characteristics of concealment, sudden occurrence, strong destructive power, and significant harm. The deterioration of rock mass caused by periodic fluctuation of reservoir water level has become a critical threat to the long-term stability of these hazardous rocks. In recent years, numerous scholars have conducted extensive research on the damage and disaster mechanisms of rock mass under the influence of water level fluctuation, as well as on instability models of dangerous rocks and stability calculation methods. Comprehensive analysis and research have led to the conclusion that advancements in test methods, testing techniques, and equipment for assessing rock mass damage caused by water-rock action have deepened our understanding of disaster mechanisms related to rock mass deterioration and instability modes of dangerous rocks influenced by changes in water levels. Furthermore, it has resulted in more scientifically sound calculation methods for evaluating dangerous rock stability. However, there are still six areas worthy of further study: disaster mechanisms and failure characteristics related to water-related hazardous rocks; laboratory simulation experiments under complex dynamic mechanical environments; in-situ tests; large-scale structural plane detection; regularity and spatial expression of rock mass damage; studies on instability models for dangerous rocks under complex dynamic conditions; cumulative damage assessment and long-term stability studies; instability failure modes associated with water-related hazardous rocks; as well as application of Remote Sensing Technology and Machine Learning Model Methods.

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• Multi-scale Perspective Bridge Damage Detection and ServicePerformance Evaluation Research: A Review

  LI Zewei, YANG Yongqing, XIE Mingzhi, HUANG Shengqian, ZHEN Xiaogang, YU Huali, ZOU Lingchen

  Abstract: (356) HTML (0) PDF (0.00 ByteKB) (0)

  Bridge inspection and service performance evaluation are critical technologies for ensuring the safe operation of bridges. This paper systematically reviews the academic progress, existing achievements, and future trends in the field of bridge damage detection and assessment, focusing on the multi-scale perspective. The research is explored from three different scales: macro, meso, and sub-micro. At the macro scale, the evolution of bridge feature detection methods is deeply analyzed, revealing the trend of transforming into rapid detection technologies based on vehicle response. At the meso and sub-micro scales, due to the complexity of bridge surface damage, existing research focuses on recognition methods based on computer vision. In terms of service performance evaluation, the existing methods for short-term bridge condition assessment and long-term condition prediction are summarized. The comprehensive analysis shows that the current bridge inspection technology has been effective in identifying bridge damage features. However, future research should still focus on two directions: macro damage identification based on vehicle response and meso and sub-micro damage identification based on computer vision. Both directions have shown great application potential. Future research should further optimize the vehicle-bridge coupling response model and improve its applicability to different forms of macro-scale damage. Studying the mapping relationship between meso and sub-micro-scale damage images and bridge mechanical characteristics. Improving the accuracy of detection with researching on the correlation of multi-scale damage. Especially, more practical bridge service performance evaluation methods are explored with engineering practice.

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• Research on the eccentric bending response characteristics of shield tunnel segments

  HUANG Yingzhou, CHEN Wen, HE Qihai, WU Zhihao, YANG Yang, ZHANG Wengang, YANG Wenyu, SUN Weixin

  Abstract: (177) HTML (0) PDF (0.00 ByteKB) (0)

  The flexural bearing capacity of shield tunnel segments is crucial for tunnel construction, as sufficient flexural bearing capacity ensures the overall stability and safety of tunnel engineering. Currently, there is insufficient research on the flexural bearing capacity of shield tunnel segments. This study employs a standardized method for detecting the bending capacity of shield tunnel segments, complemented by full-scale bending tests, to evaluate the bending capacity of segments in the Longgang shield section of the Shenzhen Shantou Railway. The effectiveness of the full-scale bending tests was verified using standard design calculation methods, and the bending capacity of the segments under eccentric compression was further analyzed through finite element numerical simulation methods. The results indicate that as the load is applied closer to the end of the shield tunnel segment, the pressure that the segment can withstand increases. The bending bearing capacity required at the center of the segment gradually decreases, while the bending bearing capacity required at the end initially increases and then decreases. When the ultimate bearing capacity that the segment can withstand under ideal conditions is applied to various eccentric working conditions, the displacement at the center of the segment gradually decreases, and the displacement at the endpoints shows a trend of initially increasing and then decreasing.

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• Research on engineering characteristics of chelated fly ash as subgrade filler

  lichaohua, chenaijun, caijianjun, dingchuanyang

  Abstract: (212) HTML (0) PDF (0.00 ByteKB) (0)

  The resourceful utilization of chelated fly ash in road engineering can reduce the occupation of land resources, but there is no consensus of its feasibility as subgrade filler. Through indoor experiments and microscopic analysis, the physicochemical properties of chelated fly ash, as well as the influence of moisture content and dry density on its engineering characteristics, were investigated in this study. The feasibility of employing chelated fly ash as subgrade filler in highway construction was explored, accompanied by proposed construction control indicators and measures to prevent environmental pollution. The results show that: (1) Chelated fly ash is classified as a type of high liquid limit silt featuring a complex microstructure and low specific gravity, with a higher optimum moisture content and lower maximum dry density compared to common fillers. (2) The primary chemical elements in chelated fly ash are Ca, Na, Si, and Cl, with major mineral components including calcium compounds, silicon dioxide, and chlorides. Calcium compounds can solidify fly ash by chemical precipitation. (3) Strength, effective cohesion, and effective internal friction angle decrease approximately linearly with increasing moisture content, and increase with increasing dry density, while permeability coefficient decreases with increasing dry density. (4) Chelated fly ash is suitable for highway subgrade filler, with recommended moisture content ranges of 22.0% to 29.5% for embankments and 24.5% to 29.5% for roadbed materials. To ensure subgrade stability and reduce environmental pollution risks, it is recommended to employ low liquid limit clay cover and waterproof geotextiles core-wrapping for combined treatment. This study provides support for determining the technical parameters of chelated fly ash subgrade filler, and holds significant engineering value for its resource utilization in road engineering.

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• Investigation of stress wave propagation characteristics in track structures under subway vibrations

  li yang, kong qing zhao, yang xia, zhou yang bin, zhu fu gang

  Abstract: (270) HTML (0) PDF (0.00 ByteKB) (0)

  During the operation of a subway, vibrations generated on the steel rails propagate as stress waves along the rail-rail pad-steel rail sleeper-ballast-tunnel-soil path. In order to investigate the variations in the fundamental characteristics of stress waves along this propagation path, this study constructed an indoor model of a subway tunnel with steel rails. A Laser Doppler Vibrometer (LDV) was used to measure stress wave signals at different locations of the experimental model, and a scanning Laser Doppler Vibrometer (LDV) was employed to capture the real propagation process of stress waves on different surfaces of the steel rails. Finally, the LS-DYNA finite element simulation software was utilized to perform a comparative analysis of the changes in wave field characteristics during stress wave propagation from an image perspective. The research results indicate that the stress wave signals generated by the wheel-rail interaction on the steel rails are mainly characterized by low-frequency signals ranging from 25Hz to 400Hz and high-frequency signals at 1400Hz. On the other hand, the stress wave signals propagated into the soil primarily consist of low-frequency signals ranging from 25Hz to 200Hz. By comparing with the measured data, the steel rail experimental model constructed in this study exhibits a consistent dynamic performance with the actual subway tunnel. The analysis of the signal data and the wave field contour maps both indicate that the high-frequency components of the stress waves attenuate most rapidly during propagation from the steel rail to the concrete sleeper, exhibiting the lowest signal energy transfer rate. The comparison between the Laser Doppler Vibrometer (LDV) and computer simulation results of the stress wave field validates the accuracy of the computer simulation method from an image perspective. Additionally, the study suggests that the results obtained from the Laser Doppler Vibrometer (LDV) can serve as an alternative to computer simulation results in the investigation of wave fields in complex media and models. The research findings hold valuable implications for the safety design and wave field analysis of subway track structures.

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• Wind-induced response and reliability parameters analysis of skeleton supported saddle membrane structure

  chenziye, liuchangjiang, lidong, zhengzhoulian, liujian, liuzhi, liuyanyun

  Abstract: (70) HTML (0) PDF (0.00 ByteKB) (0)

  The membrane structure is sensitive to wind load, and severe vibration displacement will occur under wind load. At the same time, the wind resistance design of the membrane structure lacks the support and guarantee of the reliability theory. The random vibration model and reliability theory of membrane structure under wind load can provide reference for the wind resistance design of membrane structure. Firstly, the skeleton supported saddle membrane structure is taken as the research object. Based on Von Karman's large deflection theory and potential flow theory, a theoretical model of random vibration under wind load is established. The approximate theoretical formula of wind-induced dynamic response is obtained by KBM perturbation method combined with MATLAB software. Then, according to the displacement first-passage failure criterion, the reliability performance function of the skeleton supported saddle membrane structure is established, and the reliability index and failure probability are obtained by the first-order second-moment method. Secondly, the wind tunnel test of the skeleton supported saddle membrane structure is carried out, and the vibration law of each point on the membrane is analyzed from the perspective of flow velocity and pressure. Finally, the relative phase difference is introduced to compare the theoretical results with the experimental results, and the sensitivity analysis of the parameters affecting the reliability is carried out. The results show that the theoretical results are in good agreement with the experimental results. The rise-span ratio, pretension and wind speed all have a certain influence on the reliability of membrane structure. However, from the trend of failure probability, it can be seen that the rise-span ratio has a more significant influence on the reliability of membrane structure than other variables.

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• Assessment Approach to Deterioration of Exterior Wall Tiles Based on Multiple Linear Regression Model

  yangtongyue, xuhu, zhaoshixing, yuzhixiang, longdanbing, tianyongding

  Abstract: (81) HTML (0) PDF (0.00 ByteKB) (0)

  As the risk of falling caused by deterioration of exterior wall tiles has become increasingly prominent, a multiple linear regression model is proposed to rapidly assess the deterioration degree based on field surveys. This method aims to reduce the ambiguity of existing assessment approaches while improving diagnostic efficiency. Firstly, the types of deterioration and their impacts on exterior wall tiles was classified and analyzed according to the available research, and qualitative assessment standards for deterioration was summarized. Then, the image library covering the deterioration of exterior wall tiles was established through surveys, and evaluation of the deterioration based on the proposed standards by groups was conducted. . Subsequently, an assessment model for the deterioration was built using a multiple linear regression approach, with a determination coefficient R2 of 82.45%, and the impact of independent variables on dependent variables was statistically significant. To further standardize the assessment results, a value function was introduced to process the model output, obtaining a normalized degree of deterioration assessment value. Finally, combining the regression model, value function, and rating standards of deterioration degree, a complete set of assessment approach was formed. Compared with traditional assessment ways, this approach has the advantages of being comprehensive, simple, efficient, and highly applicable, as verified through practical examples.

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• Study on dynamic simple shear characteristics of fiber reinforced granite residual soil

  liufeiyu

  Abstract: (111) HTML (0) PDF (0.00 ByteKB) (0)

  In order to study the cyclic shear characteristics of fiber reinforced granite residual soil, polypropylene fiber was incorporated into the residual soil. The horizontal cyclic simple shear test of fiber reinforced residual soil was carried out by dynamic simple shear apparatus. The effects of different fiber content ( 0,0.3%, 0.6%, 0.9% ) and cyclic stress ratio ( 0.15,0.20,0.25,0.30 ) on the dynamic characteristics of granite residual soil were analyzed. The test results show that with the increase of cyclic stress ratio, the dynamic shear strain increases. The addition of fiber effectively inhibits the development of dynamic shear strain of residual soil, and the higher the fiber content, the smaller the dynamic shear strain. The fiber increases the critical cyclic stress ratio of the residual soil. Under the critical cyclic stress ratio, the number of cycles when the reinforced sample is destroyed is much larger than that of the unreinforced sample, which indicates that the addition of the fiber increases the toughness of the soil and greatly delays the failure time of the soil sample. The dynamic shear modulus and damping ratio decrease first and then remain stable with the increase of the number of horizontal cycles. Under the same cyclic stress ratio, the larger the fiber content, the greater the dynamic shear modulus and damping ratio. For the dynamic shear modulus, the smaller the cyclic stress ratio, the more obvious the advantage of fiber reinforcement. The improved H-D model can be used to analyze the dynamic response of granite residual soil under different cyclic stress ratios and different fiber contents.

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• Measurement and analysis of wheel-rail forces and vibration damping effects of steel-spring floating slab in soft-soil site

  YE Junneng, SHENG Tao, BIAN Xuecheng

  Abstract: (197) HTML (0) PDF (0.00 ByteKB) (0)

  In order to evaluate the influence of steel spring-floating plate track on wheel-rail forces and its actual vibration damping effects in a deep soft-soil tunnel, steel spring floating plate track bed and ordinary integral track bed were selected to meet the three preconditions of similar geological conditions, the same buried depth of the tunnel, and the same train speed and load. The vertical and lateral wheel-rail forces and rail deformation were tested respectively, and the three-direction vibration acceleration time travel curve of its rail, sleeper plate and tunnel wall, expand the time domain and frequency domain analysis. The results show that: (1) the floating plate can increase the vertical wheel-rail force slightly, increase the transverse wheel-rail force greatly, and make the low-frequency quasi-static action of wheel-rail force take a larger proportion; (2) The incensement of low-frequency components of wheel-rail forces cause the low-frequency jitter of the floating slab, resulting in a significant increase in rail displacement and volatility, and its vertical and lateral displacement increased by 2.4 times and 4 times respectively, which will have an adverse effect on smooth running; (3) The transverse and vertical vibration acceleration levels of the soft-soil tunnel wall were reduced by 5 dB, and the longitudinal vibration changed little, while the transverse and vertical vibration acceleration levels of the sleeper plate were increased by 10~12 dB, which proves that the floating plate effectively blocks the vibration energy. (4) The transverse and vertical resonance frequencies of the tunnel are about 50 Hz, and the floating slab effectively suppress the transverse and vertical vibration levels by 10~18 dB, satisfying the performance requirements of special vibration reduction measures. It shows that the increase of low frequency wheel-rail force has little effect on the high frequency vibration isolation performance of the floating slab, and the steel-spring floating slab is also appropriate to soft-soil subway tunnels.

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• Micromechanical Analysis of Shear Properties at the Interface between Granite Residual Soil and Geotextile

  YU Wei, GAO Pin-hong, LIU Fei-yu

  Abstract: (75) HTML (0) PDF (0.00 ByteKB) (0)

  To delve into the micromechanical deformation and failure mechanisms of the geogrid-soil interface, a series of direct shear test models for granite residual soil with geotextiles containing different rock contents (50%, 75%, and 100%) under two loading conditions (normal static load and normal cyclic load) were established using the discrete element software PFC3D, based on the results of large-scale indoor direct shear tests. The study analyzed changes in micromechanical shear characteristics such as porosity, coordination number, fabric anisotropy, and particle rotation at the geogrid-soil interface. The results indicated that the change in sample porosity increased with higher rock content and was primarily concentrated near the shear plane, with normal cyclic loading causing a slight increase as well. The coordination number at the interface ranged between 5.19-6.05, 4.74-5.77, and 4.35-5.53 as the rock content increased, indicating a reduction in particle contacts. Under both loading conditions, the principal direction of anisotropy of contact forces between particles shifted, with the normal contact forces under normal static load being greater than those under normal cyclic load. The average rotation angle of particles with 100% rock content was smaller than that with 50% rock content, and normal cyclic loading caused a slight increase. Overall, the rotation angle distribution was normally distributed, with the maximum value located near the shear plane.

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• Disintegration Characteristics and Disintegration Inhibition Mechanism of Organosilicone-Modified Carbonaceous Mudstone under Dry and Wet Cycling Effects

  HE Zhijun, ZENG Ling, ZHA Huanyi, FU Hongyuan, CHEN Jingcheng, ZHANG Hongri

  Abstract: (105) HTML (0) PDF (0.00 ByteKB) (0)

  s: To reduce the degradation of strength and inhibit the disintegration of carbonaceous mudstone by wet and dry cycling, tests on the unconfined compressive strength and disintegration of silicone-modified carbonaceous mudstone under wet and dry cycling were carried out. The effects of the number of dry and wet cycles and the amount of organosilicon on the unconfined compressive strength, grain size gradation, inhomogeneity coefficient and curvature coefficient of the modified charcoal mudstone were studied, and the inhibition effect of organosilicon on the strength deterioration and disintegration characteristics of the charcoal mudstone was clarified. The changing law of microstructure of organosilica-modified carbonaceous mudstone under dry and wet cycling was also analyzed by scanning electron microscopy to reveal its mechanism of inhibiting disintegration. The results showed that the unconfined compressive strength of modified carbonaceous mudstone was positively correlated with the organosilicon dosing and negatively correlated with the number of wet and dry cycles. Organosilicon can effectively increase the grain size of carbonaceous mudstone, and the content of coarse particles larger than 2mm, the maximum grain size(Dmax) and the minimum grain size (Dmin) of modified carbonaceous mudstone were significantly increased after the incorporation of organosilicon. Meanwhile, the particle content of modified carbonaceous mudstone in the [10mm, 20mm), [5mm, 10mm) and [2mm, 5mm) grain groups changed most drastically during the disintegration process, but the greater the organosilicon doping, the smaller the magnitude of the change in grain size. Moreover, the higher the silicone doping, the smaller the change in particle size. The median grain size (d50), Weibull distribution parameters (λ, k), fractal dimension (D), disintegration resistance index (Idn) and disintegration ratio (Dr) of modified charcoal mudstone were positively correlated with silicone dosing and negatively correlated with the number of wet and dry cycles. However, the variation rule of the inhomogeneity coefficient (Cu) is opposite to it. The organosilicones mainly inhibit the strength deterioration and disintegration of carbonaceous mudstone particles through the network structure of the colloidal link and the formation of hydrophobic film on the surface layer of the carbonaceous mudstone particles.

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• Dynamic calibration method for finite element models of bridges considering structural performance degradation

  CHEN Ge, ZHONG Wanbo, FAN Aimin, ZHENG Xing, LU Wei, QIAO Zhengqi, ZHOU Guangdong

  Abstract: (115) HTML (0) PDF (0.00 ByteKB) (0)

  The multiple independent updating of finite element models based on the random search is difficult to describe the dynamic laws of the structural performance degradation and the component damage deepening and expanding to adjacent components as the service time of the bridge increases. This paper proposes a dynamic calibration method for bridge finite element models considering structural performance degradation based on the Cuckoo Search Algorithm (CS algorithm). Firstly, the set of parameters to be updated corresponding to the code of the CS algorithm is divided into three groups: diseased components, adjacent components to diseased components, and other components. Then, different strategies are used to initialize each group of codes, and the upper limit of the parameters to be updated is set to the previous updating result. Finally, the search range for each group of codes is limited by setting different control factors for the step sizes. At the end of the paper, a single span truss bridge was used to verify the effectiveness of the proposed method. The research results indicate that the dynamic calibration method of the finite element model based on the CS algorithm can dynamically calibrate the finite element model of bridges. The dynamically calibrated finite element model can describe the time-varying behavior of the operation performance of bridges as the disease deepens over time and extends to adjacent components.

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• State-of-the-art research of bridge thermal action and effects in 2020

  xiaolin

  Abstract: (506) HTML (0) PDF (0.00 ByteKB) (0)

  Temperature action is one of the important loads in bridge construction and operation stages. With the extension of traffic network, severe climate could be expected to cause larger temperature action than those recommended in the specifications. The complexity of traffic environment also increases the probability of bridge fire and related damage. In-depth study of bridge ambient and fire temperature field, and identification of its actions and effects can ensure the safety of bridge from the aspects of design, construction and maintenance. This study reviews the latest domestic and overseas research on ambient temperature action, temperature effect and bridge fire action in 2020, and prospects the hotspots and directions of the future research of bridge thermal action and effects.

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• State-of-the-art review of timber bridge in 2020

  Zhao Ran, Zhang Rui, Hu Peng, Chen Kedao

  Abstract: (431) HTML (0) PDF (0.00 ByteKB) (0)

  Timber bridge is a kind of bridge built with timber as the main building material, which is eco-friendly, lightweight and aesthetic, convenient for construction, and reliable in performance. In recent years, as the gradual recovery of forest resources in China, and the processing, anticorrosion and connection technologies of modern timber structure are improving continuously, timber bridge has become an ideal type of middle and small span bridge. To better adapt to the current situation of bridge construction and promote the application of wooden bridges, in this paper, the application status of timber bridge, timber decking technology, the detection and strengthening technology, timber-concrete combined bridges and other aspects are summarized. Hoping to assist the reference of practitioners in the industry.

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• State of the art on prefabricated concrete bridge structures in 2020

  XuZIYi, ZhangZiyang, XuTengfei

  Abstract: (1059) HTML (0) PDF (0.00 ByteKB) (0)

  Prefabricated bridges have become an important development direction of bridge construction due to the advantages of good construction quality, low impact on the environment, short on-site operation time, and high level of construction safety. Prefabricated concrete bridges are not only suitable for urban road bridges with complex traffic, but also for railway bridges in difficult construction environments. This paper sorts out the research progress of prefabricated concrete bridges at home and abroad in 2020 through the method of literature research. According to the type of bridge structure, new technologies, new structures and typical engineering applications in this field are discussed from two aspects: the upper structure and the lower structure. After a rough summary in this article, in the superstructure, the connection structure, crack resistance and durability of the nodes have received extensive attention from scholars; in the substructure, as the prefabricated system is applied to the bridge in the high-intensity earthquake area, The structure and seismic performance of prefabricated bridge piers are currently a hot research topic. The durability and crack resistance of the substructure still needs to be improved.

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• Research progress of Bridge Assessment and reinforcement in 2020

  zhangfang

  Abstract: (350) HTML (0) PDF (0.00 ByteKB) (0)

  Due to the contradiction between the demand of bridge construction brought by the rapid economic development and the backward technical reserve in the period of large-scale construction, China will face the increasing pressure of bridge maintenance in the next 10 to 30 years. Based on the latest research progress in the field of bridge evaluation and reinforcement, this paper introduces the chemical and physical methods of the main bridge disease monitoring technology, the bridge health monitoring technology and equipment including sensor technology and signal processing technology; The bridge health evaluation method based on time-varying reliability theory and historical data is compared, and the significance of structural parameter inversion relative to artificial intelligence is discussed; The partial reinforcement methods for bending, shearing and seismic resistance, the integral reinforcement methods for additional structural systems, and the electrochemical chlorine removal technology are introduced. The decision-making methods of maintenance and reinforcement of network level and project level are introduced. Considering the cross-disciplinary characteristics, some advanced sensor, signal processing technology and evaluation theory are also introduced in order to clarify the internal logic, may be able to play a certain inspiration and train of thought inspiration.

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• State-of-the-art review of planning and protection of bridgeCultural heritage in 2020

  Zhang Fang, Deng JieChao, Zhang Kaiquan, Yang Qian, Qian Yongjiu

  Abstract: (291) HTML (0) PDF (0.00 ByteKB) (0)

  In the process of cultural integration in the world, all countries pay more attention to the protection of their cultural heritage. As a kind of heritage of comprehensive human activities, bridge cultural heritage has many attributes such as transportation heritage, architectural heritage, urban planning heritage, industrial heritage, etc., and has been paid more and more attention by all countries in the world. However, at present, compared with other cultural heritages, the research and practice of bridge cultural heritages in the global scope are still immature and have not formed a system. Through the statistics of ancient bridge, ancient bridge culture and related research in the past 20 years in China, we can clearly see the overall status of bridge cultural heritage research in China. Moreover, based on the induction and analysis of the research results of bridge cultural heritage at home and abroad in 2020, the paper expounds and summarizes the research progress of bridge cultural heritage at home and abroad in 2020, and looks forward to the planning and protection of bridge cultural heritage in the future.

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• Research progress on fatigue of steel bridge in 2020

  Zhang Qinghua, Lao Wulue, Cui Chuang, Bu Yizhi, Xia Song

  Abstract: (637) HTML (0) PDF (0.00 ByteKB) (0)

  Steel bridge has outstanding advantages, such as high ratio of strength to weight, large span capacity, easy to factory manufacturing and assembly construction, where bridge engineering is going in the further. However, the engineering practice shows that fatigue and fracture are the decisive factors to reduce the service performance of steel structure and cause catastrophic accidents, which seriously restrict the development and application of steel bridges. The in-depth and systematic researches on this practical engineering problem from different perspectives have been have conducted at home and abroad. To clarify the urgent problems and determine the research focuses and development directions in the next stage, the latest research progress in fatigue of steel bridge are summarized, including fatigue failure mechanism and fatigue resistance assessment method, anti-fatigue design and construction technology, environmental factors and their effect mechanism to fatigue resistance, fatigue crack identification, monitoring and detection, fatigue crack treatments and fatigue performance enhancement. The results demonstrate that the fatigue issue is a hot topic to researchers and engineers. the researches on fatigue critical problems in steel bridge has made adequate progress. Based on the studies including anti-fatigue design method, structures with high fatigue resistance, fatigue resistance assessment method, construction technology, fatigue damage monitoring and fatigue micro-crack identification, remaining fatigue life prediction and fatigue performance enhancement, it is the research emphasis and future directions to establish the fatigue resistance technology of steel bridges in life cycle.

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• Research progress of explosion and fire resistance of bridges in 2020

  cuichuang, Yang Zhengxiang, Wang Hao, Zhang Qinghua, Bu Yizhi, Xia Song

  Abstract: (440) HTML (0) PDF (0.00 ByteKB) (0)

  The demand for energy exchange increases as the rapid development of regional economy, and the number of vehicles loading and transporting "burning, vapour, explosion and chemical" dangerous chemicals is increasing. The structural safety of bridge in-service is seriously threatened due to the explosion and fire caused by the vehicles emerge in an endless stream. As a hot topic in the field of bridge disaster prevention, scholars at home and abroad have made fruitful research in the field of bridge explosion and fire resistance. Based on the publications in 2020, this paper briefly summarizes the research results at the present stage. This paper focuses on the explosion impact load test and numerical simulation method, bridge fire test and simulation technology, bridge anti-explosion performance and deterioration mechanism, bridge damage mechanism and safety assessment under fire, bridge anti-explosion safety assessment method, bridge performance evolution and disaster mechanism after overfire. The explosion test technology at present through the analysis of the system and research the mechanics characteristics of structure under high strain rate, complicated fire environment temperature transmission and distribution, coupled damage evolution of the bridge subjected on multi-disasters, disaster mechanism and bridge structure safety assessment system are of lack and urgent need. In order to ensure the service safety of bridge structure in the whole life cycle, the structural characteristics and operation and maintenance safety under extreme load conditions such as explosion and fire have been is of primary importance in the operation and maintenance of bridge.

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• Research progress in 2020: vibration and noise reduction of rail transit bridges

  Li Xiaozhen, Zheng Jing, Bi Ran, Zhang Xun, Luo Hao, Cao Zhiyang

  Abstract: (428) HTML (0) PDF (0.00 ByteKB) (0)

  With the rapid development of high-speed railway and urban rail transit, the problems of vibration and noise become more and more prominent. The noise mitigation of traditional vertical sound barrier was obvious on wheel rail noise, but is insufficient when the train speed exceeds 250 km/h. Therefore, fully enclosed sound barrier is pushed the construction alongside high-speed railway In recent years, steel bridges or steel-concrete composite bridges have gradually been widely applied in high-speed railway and urban rail transit. Steel bridges or steel-concrete composite bridges have greaterer sound radiation ability, wide spectrum, large amplitude and difficult to control. Therefore, it is urgent to solve the noise radiation issue wheng steel bridges or steel-concrete composite bridges are built in environmentally sensitive areas. Focusing on the two study directions of "noise reduction performance and dynamic characteristics of high-speed railway sound barrier" and "vibration and noise reduction of steel bridge", the research trends and development trend of this direction are briefly reviewed in this article.

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• State-of-the-art review of the Numerical simulation of ridge structure in 2020

  zhoulingyuan

  Abstract: (443) HTML (0) PDF (0.00 ByteKB) (0)

  Zhou Linyuan (School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031，China) Abstract: With the development of computer technology and in-depth study of computation theory, numerical analysis has become the major analysis method for bridge structure. At present, through the numerical simulation of bridge structure, the mechanical behavior and response under various complex actions can be obtained, with which the calculation efficiency and adaptability are far higher than those of analytical method and model test. Based on the relevant research results at home and abroad in recent years, the application of numerical analysis technology in bridge structure analysis and the latest research results are summarized. This paper mainly focuses on the finite element numerical simulation technology related to the analysis of the main mechanical behavior of bridge structure, including the latest research direction of beam theory, the nonlinear analysis methods and technologies, the research progress of a variety of numerical constitutive models for bridge structure materials, and the timeliness of Mechanical properties of bridge structures under corrosive environment. The new development of finite element method and numerical simulation method of composite structure based on beam theory are summarized. Finally, the problems that need to be further studied and solved in this field are analyzed and prospected.

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• State-of-the-art Review of Vehicle-Bridge Coupling Vibration in 2020

  Li Xiaozhen, Wang Ming, Jin Zhibin, Zhu Yan, Qiu Xiaowei

  Abstract: (477) HTML (0) PDF (0.00 ByteKB) (0)

  The main research contents of vehicle-bridge coupled vibration include vehicle-bridge coupled vibration and random vibration under the effect of track irregularity, wind-vehicle-bridge coupled vibration, earthquake-vehicle-bridge coupled vibration, new rail vehicle-track beam coupling Vibration and other aspects. At present, the construction of railway bridges in China is facing new challenges such as larger spans, high speeds, and high comfort levels. Under external excitations such as wind loads and train loads, the vehicle-bridge interaction is becoming more and more significant. How to accurately predict the dynamic response of the vehicle-bridge coupling system and the running performance of high-speed trains in the actual complex wind environment, and provide technical guidance for bridge design, line operation, maintenance and management, and become a research hotspot and development trends in the field of vehicle-bridge coupled vibration in 2020.

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• Advances in the Implementation of UHPC-OSD System

  Xia Song, Chen Liu, Yang Xu

  Abstract: (1595) HTML (0) PDF (0.00 ByteKB) (0)

  Ultra High Performance Concrete (UHPC) is combined with the Orthotropic Steel Deck (OSD) in a lot of projects nowadays. That is a typical example of the implementation of new materials and new structures in bridge engineering. Benefitting from its high stiffness, UHPC slab can evidently reduce the local deformation of OSD. In this way, we can greatly reduce the fatigue stress amplitude and the fatigue resistance is increased. In the present work, we reviewed the research advances on the composite UHPC-OSD system from five aspects: the new structures, the shear connectors, the basic static behaviors of the composite deck, the fatigue performance of the composite deck and the basic mechanical properties of UHPC or UHPC members. Most of the concerned literature was published in 2020 or 2021. However, some works reported in a few other recent years were still mentioned in the present work.

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• State-of-the-art review of the bridge health monitoring in 2020

  ShanDeShan, LuoLingFeng, LiQiao

  Abstract: (222) HTML (0) PDF (0.00 ByteKB) (0)

  The bridge health monitoring system (BHMS) continuously measures and records the structural responses by using a variety of sensors and communication devices in the bridge operation process. The automatic analysis of signal data can be done effectively in the BHMS to fulfill the timely danger warning and safety assessment. The BHMS leads to the better transportation operation of bridges, the longer service life of bridges, and the more reasonable determination of the bridge management and maintenance for engineers. For the sake of the more efficient application of health monitoring system in bridge engineering, this paper summarizes the current states of several representative BHMS techniques: signal denoising, signal warning, modal parameter identification, finite element model updating, damage identification, condition prediction and assessment. Then, the related researches and applications of these key techniques during 2020 are summarized and discussed. Consequently, it is found that the machine learning methods have been more and more widely used in the current research of key technologies of the bridge health monitoring.

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• State-of-art review of the durability of concrete bridges in 2020

  ZHAN Yulin, SI Ruizhe, ZANG Yamei

  Abstract: (494) HTML (0) PDF (0.00 ByteKB) (0)

  In recent years, the durability of concrete bridges has attracted extensive attention from researchers and has been one of the hot topics in bridge research. The durability of concrete bridges can affect the safety and service life of bridges directly. Currently, the research on the durability of concrete bridges is mainly divided into two aspects: (1) From the perspective of the damage mechanism of the materials, the damage modes and influence factors of the bridge component materials are studied and the influence mechanism of the durability of the concrete bridge materials is analyzed; (2) From the whole of the bridge structure, the design and evaluation of the durability of the bridge and the maintenance of the bridge are studied, and the methods to improve the durability of the concrete bridge structures are explored. In order to grasp the research trend on the durability of the concrete bridge, this paper reviewed the literature on the durability research of concrete bridges by domestic and foreign scholars in 2020, from the design of the concrete bridge, the durability of the concrete material research, the study of concrete bridge reinforcement corrosion and the durability of concrete bridge improving technology, the influence of different service environment on the durability of the bridge, performance evaluation and service life prediction. The research focus and development direction of the durability of concrete bridges in the future are discussed.

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• State-of-the-art research of steel-concrete composite bridges in 2020

  Wei Xing, Xiao Lin, Wen Zongyi, Kang Zhirui

  Abstract: (677) HTML (0) PDF (0.00 ByteKB) (0)

  Steel-concrete composite bridges, one of the sustainable structural forms, have excellent composite technical, economic and social results, and are increasingly popular in the bridge engineering. The steel-concrete composite structure can give full play to the material advantages of concrete and steel, and has been widely used in many fields of structural engineering, because of the reasonable load transfer, the economic efficiency, and the ease of construction. In order to accelerate bridge construction to assemblage, greening and intellectualization, promoting the use of steel-concrete composite structures in small and medium-span bridges faces opportunities and challenges. Two major categories, including research on commonly used shear connectors and steel-concrete composite girders in 2020, are collected, categorized and reviewed. Research on shear connectors covers the basic mechanical properties of stud connectors, PBL connectors, bolt connectors, and improved connectors, as well as the durability and degradation properties of connectors. Research on composite beams includes theoretical models, combined effects and spatial behavior, performance in the negative moment zone, dynamic characteristics of composite beams, deterioration performance, detection and reinforcement, construction methods.

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• Research progress of bridge construction monitoring in 2020

  yangyongqing, Gaoyufeng, Huangshengqian, Wubinbin

  Abstract: (557) HTML (0) PDF (0.00 ByteKB) (0)

  Bridge construction monitoring is an important part of bridge construction technology, is the key to ensure the quality of bridge construction, is the safety guarantee of bridge construction, has become an important content of research in the field of bridge engineering. By means of literature research, with the keywords of "construction control / monitoring ", "construction control theory / method", "construction monitoring system" and "intelligent monitoring", more than 60 scientific research papers published in 2020 were searched and sorted on Web of Science, Science Direct and CNKI. This paper mainly summarizes the research progress of domestic and foreign scholars in the aspects of bridge construction control theory, construction control parameter identification and state prediction, bridge construction monitoring system and intelligent monitoring, and the hot spots of bridge construction control research in the future were prospected.

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• The State-of-the-art in Steel Bridges

  zheng kaifeng

  Abstract: (279) HTML (0) PDF (0.00 ByteKB) (0)

  In order to promote the development of steel bridge technology, research hot issues and frontiers in recent years in the field of steel bridges at home and abroad were systematically sorted out. Firstly, it reviews the recent construction achievements and technological progress of large-scale steel bridges in China. Then the latest progress made in the main research directions in the field of steel bridges were systematically summarized. At the same time, many pioneering work done in various aspects of the steel bridge are introduced in detail. It is expected to provide basic information and reference for engineering applications and academic research in the field of steel bridges.

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• State-of-the-art review of the bridge foundation engineering in 2020

  JIANG Xinyu, WU Shouxin, FENG Jun, LI Xiaogang, LI Yi

  Abstract: (174) HTML (0) PDF (0.00 ByteKB) (0)

  The foundation of a bridge is an essential structural part linking the bridge with the ground, and its function is to transmit the loads smoothly from piers and abutments to the supporting strata. Unlike foundations of other civil structures, the foundations of bridges are subjected to dynamic loads coming from the superstructures, usually located in water or even deep water and torrents, and have large volumes and self-weights. Consequently, there are special issues related to the design, construction, and maintenance of bridge foundations need to be addressed, especially those relevant to the bridges crossing wide rivers, deep seawaters, and poor geological terrains. Based on the published journal articles and reports, this paper reviews the progresses in the research and development of bridge foundation types, foundation scour, foundation construction, and seismic resistance of foundations. Existing issues in the research and development of bridge foundations are discussed and, based on the discussion, the following topics are suggested for future studies: water-sediment interaction theory and mechanisms of sediment transport for scour at deep water foundations; advanced deep-water foundation structures suitable for China’s sea bedrock; key techniques for positioning and setting of large caisson foundations; and dynamic soil-foundation-structure interaction under earthquake.

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• State-of-the-art review of concrete bridges and its high performance materials in 2020

  Zhao Renda, Zhan Yulin, Xu Tengfei, Li Fuhai, Zhao Chenggong, Zhang Jianxin, Yang Shiyu, Yuan Yuan, Wen Xi

  Abstract: (165) HTML (0) PDF (0.00 ByteKB) (0)

  In order to understand the development trend of the research direction of concrete bridge and high-performance materials in 2020, and on the basis of summarizing the research contents, methods and achievements, the follow-up research will be carried out better, this paper reviews the recent literatures from the three aspects of concrete bridges, high-performance concrete materials and high-performance reinforced materials. Furthermore, the literature are classified, summarized and commented. The results show that the current research on concrete bridges pays more attention to durability in the operation stage, working performance in extreme environments, and concrete bridge accidents. For high-performance concrete materials, great progress has been made in the three aspects of high performance, green environmental protection and intelligence. The related high-performance reinforced materials have been mainly focused on the FRP bars with higher strength and better durability. Its application in beams, slabs, columns and other components has been widely studied. Finally, the paper points out shortcomings of the existing research and the work to be done in the future.

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• State-of-the-art review of hydrology for bridges and culverts in 2020

  Zhang Ming Jin

  Abstract: (470) HTML (0) PDF (0.00 ByteKB) (0)

  Hydrology for bridges and culverts is mainly based on the river and hydrological environment and other factors for bridge design, which is an important basic work of bridge site environmental design. By reviewing the development of hydrology for bridges and culverts in recent years, some key issues from hydrology of bridges and culverts, such as research methods, design flood discharge, causes of bridge foundation scour and influencing factors, and calculation of the scour depth of bridge piers and abutments, elaborated the development achievements of hydrology for bridges and culverts and briefly summarized the current difficulties and future hotspots.

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• State-of-the-art review of BIM Technology in Bridge Engineering in 2020

  ZHAO Bin, XIE Shangying, HE Wei

  Abstract: (355) HTML (0) PDF (0.00 ByteKB) (0)

  Building information modeling is regarded as the second revolution of engineering design after CAD, is the key to digital transformation of civil Engineering Industry. But the application in bridge engineering is still rare, and research and application still need to be strengthened. In order to provide some references and new ideas for the future development of BIM in bridge engineering, this paper reviews, summarizes the research and application progress of bridge engineering BIM in 2020 from the following three aspects: (1) industrial policy, standards and guide, (2) basic research and software development, (3) application in bridge engineering.

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• State-of-the-art review of bridge hydrodynamics in 2020

  weikai, qinshunquan, zhaowenyu, zhubing, xuguoji

  Abstract: (212) HTML (0) PDF (0.00 ByteKB) (0)

  To understand the development trend of the research of bridge hydrodynamics and on the basis of summarizing its research contents, methods and achievements, the follow-up research will be carried out better, this paper reviews the recent literatures published in 2020 from the aspects of wave current effect, local scour of foundation, fluid solid coupling, multi disaster effect of extreme marine environment, etc. It is found that the research hotspots of bridge hydrodynamics mainly focus on the models of an extreme wave, current action, and wave-current interaction, the influence factors and depth prediction of pier local scour, the fluid-structure coupling of the deep-water bridge under earthquake action, the combined effort of wind and wave Disaster assessment and risk analysis of bridge in an extreme marine environment, response analysis and optimization design of long-span floating bridge structure. By combing the shortcomings of the existing research, the following urgent research directions are proposed: structural fluid-structure coupling in extreme wave and current environment, pier erosion monitoring and protection, intelligent and information-based bridge hydrodynamic disaster prediction, and multi disaster research. It is expected to make joint efforts with relevant scholars to contribute to the development of bridge hydrodynamics.

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• State-of-the-art review of bridge wind engineering at 2020

  Haili Liao, Mingshui Li, Cunming Ma, Qi Wang, Yanguo Sun, Qiang Zhou

  Abstract: (412) HTML (0) PDF (0.00 ByteKB) (0)

  With the construction of super-long span bridges, such as the Canakkale 1915 Bridge in Turkey, the Zhanggao River-crossing Corridor and the Xihoumen Highway-Railway Bridge in China, the wind engineering research of bridges is facing new challenges. Following the research progress of the previous year, this paper focuses on the key problems of bridge wind engineering, including bridge flutter, vortex-induced vibration and buffeting. Through sorting out the literatures of main academic journals in the field of wind engineering, the state-of-the-art focusing on the main aspects of wind-resistant of long-span bridges in 2020 was reviewed and discussed.

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• State-of-the-art Review of Big Data on Bridge Engineering in 2020

  Yu Chuanjin, Chen Qian, Liang Aixia, He Jiayong

  Abstract: (239) HTML (0) PDF (0.00 ByteKB) (0)

  Under the background of the information era, the application of big data on bridge engineering has become a hot topic. The massive data obtained from data collection methods like bridge health monitoring have brought great challenges to bridge engineering practitioners in terms of data processing and application. Focusing on the research progress of big data on bridge engineering in 2020, this article reviews data preprocessing methods such as efficient storage, exception handling, redundancy and noise reduction, and focuses on specific applications of big data such as damage identification, condition assessment, and intelligent management. The relevant research progress of big data on bridge engineering in 2020 is sorted out and the existing achievements along with the focuses and difficulties of future research applications are summarized.

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• Progress in construction technology of deep-water long-span bridges in 2020

  Liu Junling, Yang Hanbin, Yang Wanli, Zhang Yuzhi

  Abstract: (728) HTML (0) PDF (0.00 ByteKB) (0)

  With the increasement of economic strength and significant improvement in science and technology, bridge engineering is developing rapidly towards larger span, deeper foundation and higher tower. Many new problems appears to bridge builders, such as: accurate positioning of deep water foundation during floating and sinking, anti-erosion of super-large caisson foundation, large diameter drilled pier construction, optimization of anchoring structure in long-span cable-stayed bridge tower, temperature control of hydration heat for mass concrete of ultrahigh bridge tower, development of new hydraulic climbing template system for ultrahigh bridge tower. These are the key problems for safe and smooth construction and long-term reliable operation for deep-water long-span bridges. The development and achievements gained in 2020 related to those key problems are analyzed and summarized to improve the construction technology, the problem-solving capacity of the builders and to give technical support for the promotion of deep-water long-span bridges.

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• State-of-the-art review of the technology in bridge structure test in 2020

  PU Qianhui, XU Xikun, WU Yining, HUANG Shengqian, HONG Yu

  Abstract: (359) HTML (0) PDF (0.00 ByteKB) (0)

  The bridge structure test is mainly a means to obtain the behavior of the bridge structure by applying static or dynamic action on the prototype or model of the bridge structure and using measuring and test techniques to collect precise and reliable test data, so as to solve the problems existed in scientific research and design in the field of bridge engineering. As an important means to promote the development of the bridge engineering field, the bridge structure test has been playing an important role for a long time. In recent years, with the progress of measuring and test technology, the technology in bridge structure test has also been widely concerned by scholars. In order to promote the further development of this field and guide the popularization and application of advanced measuring and test techniques in the field of bridge structure test, this paper systematically introduces the technical methods of three critical aspects: bridge model test, bridge field test and measuring and test technology of bridge, and reports and summarizes the enlightening related research in 2020. Finally, it is found that the technology in bridge structure test is further developing towards the integration of multi-disciplines.

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• State-of-the-art review of cloud computing for bridge engineering in 2020

  Yang Xingwang

  Abstract: (363) HTML (0) PDF (0.00 ByteKB) (0)

  Further development of bridge construction, integration of bridge design – construction – maintenance, refined management of bridge operation in China put forward higher requirements for data storage, computing capacity, etc. Cloud computing is an effective measure to satisfy the demands. By means of literature retrieval, cloud computing applications in bridge engineering in recent years are summarized, including bridge health monitoring (SHM), big data and internet of things in the bridge, BIM and collaborative design based on cloud computing. The feasible focuses of future research and application are suggested.

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• State-of-the-art Review of Reliability in Bridge Engineering in 2020

  Bin Wang, Ganggui Tang, Jishun Tang, Weixu Wang

  Abstract: (325) HTML (0) PDF (0.00 ByteKB) (0)

  Due to the uncertainty of the inherent properties and the complexity of the environment, bridges need to have sufficient reliability in different stages of design, construction, and operation. In order to understand the latest developments in the research and application of bridge engineering reliability in 2020, the relevant theoretical methods, scientific research content and results at different stages are summarized through literature review. In terms of the bridge reliability theory and methods, GPR models and radial basis neural networks are introduced to obtain the implicit structural function functions. Copula theory is introduced to consider the relationship between the probability of multiple failure modes. The probabilistic reliability and non-probabilistic reliability Methods, Monte Carlo simulation, time-varying reliability theory, etc. are used for reliability evaluation. The technical status and reliability of existing bridges are still hot spots in the field of bridge engineering at home and abroad. The time-varying model of bridge resistance and external load under environmental conditions is the focus of the time-varying reliability analysis and the life prediction of bridges. Reliability theory and analysis methods have been gradually developed in bridge engineering design. There are more and more dynamic reliability studies and applications that consider the randomness of dynamic load action and the randomness of structural parameters.

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• New progress and prospect of bridge impact research in 2020

  liuzhanhui

  Abstract: (383) HTML (0) PDF (0.00 ByteKB) (0)

  Bridge impact is a key problem for existing bridges and bridges under construction for a long time. The research on impact and protection problems meets the needs of national development. In recent years, scholars at home and abroad have paid more and more attention to bridge impact, and conducted a lot of researches. Following the New Progress and Prospect of Bridge Impact Research in 2019, the author continues to summarize the progress in 2020 in three aspects, such as bridge ship collision, rockfall impact and vehicle collision bridge. Among them, for the bridge ship collision problem, the new code clearly proposes that the main structure of highway bridge should adopt the performance-based anti-collision design method. In 2020, a series of sand mining vessel collision accidents, the broken of Yaxi high-speed bridge, and many vehicle bridge collision events have occurred. The author sortes these bridge impact events, analyzes and summarizes the relevant achievements in the past year according to personal understanding, and then puts forward the problems that need to be further considered in the future research.

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• State-of-the-art review of bridge informatization and intelligent bridge in 2020

  Zhao Tianqi, Gou Hongye, Chen Xuanying, Li Wenhao, Liang Hao, Chen Zihao, Zhou Siqing

  Abstract: (1292) HTML (0) PDF (0.00 ByteKB) (0)

  With the advent of digital era characterized by informatization and intelligence, the development and innovation of bridge engineering technology are promoted. It is necessary to integrate cloud computing, big data, artificial intelligence, 3D printing, robot and other strategic emerging industrial technologies with bridge engineering, and promote the industrialization, digitization and intelligent upgrading of bridges from multiple dimensions such as intelligent design, construction, operation and maintenance. This paper reviews related frontier technologies and important achievements worldwide in 2020, with regard to bridge informatization, intelligent inspection, safety operation and maintenance, intelligent disaster prevention/mitigation, intelligent materials, and summarizes the research hotspots and prospects. According to the review, BIM technologies can improve the refinement of bridge forward design, the accuracy of construction process control and management. Intelligent inspection technologies (e.g. UAV and robots) and artificial intelligence technologies (e.g. machine learning and convolution neural network) improve the accuracy and efficiency of bridge inspection and monitoring. Applications of high-performance intelligent materials promotes the self-perception, self-adaptability, self-adjustment and self-diagnosis of bridge. Natural disaster monitoring and early warning based on artificial intelligence (AI) provides new development idea for bridge intelligent disaster prevention. To conform to the development trend of informatization and intelligence, future research should deeply integrate artificial intelligence technology into the whole life cycle of bridge design, construction and maintenance to realize the dream of bridge power.

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• State-of-the-art Review of Risk Assessment on Bridges Construction in 2020

  Shi Zhou, Yu Wangqing, Zhou Yongcong, Ji Feng, Zhang Yuzhi

  Abstract: (254) HTML (0) PDF (0.00 ByteKB) (0)

  To understand the specific contents of bridge construction risk assessment and the development trend in the past year, and to carry out the better follow-up research on the basis of summarizing the research content, methods and achievements, the recent literatures were consulted, classified, summarized and commented from four aspects of the bridge construction risk identification, risk probability and loss estimation, risk assessment and control, dynamic risk assessment. The results show that the composite risk identification method, risk identification database system and visualization were developing continuously. The quantitative probability correction based on monitoring data and the construction of social loss model were the new development of risk probability and loss estimation. The new development of risk assessment was based on clustering or data field risk assessment method and the improvement of model accuracy. The fine modification of risk chain transferring model and dynamic evaluation model based on monitoring data were the new directions of dynamic risk assessment. Finally, some suggestions were put forward for the shortcomings of the existing research and the further development of this direction, which can be references for the work to be done in the future.

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• New Research Progress on Bridge Aesthetics in 2020

  Yan Liang, He Wei, Maolin Tang

  Abstract: (281) HTML (0) PDF (0.00 ByteKB) (0)

  This article sorts out the domestic and foreign development of bridge aesthetics in recent one year to review the development achievements by some aspects such as bridge aesthetic thought and theory, bridge aesthetic design methods and theory, bridge landscape design and reconstruction, bridge planning and design, bridge design and research on culture and history, new technology application on bridge aesthetic design, bridge aesthetic design and practice etc. Brief prediction of future research hotspots and development directions are made and the author"s suggestions and viewpoints are put forward in the end, hoping to be benefit with bridge aesthetics theory and design practice.

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• State-of-the art review of box girder and cable-supported bridge analysis theories in 2020

  BAI Lunhua, SHEN Ruili, MIAO Rusong, ZHANG Xinbiao, WANG Lu

  Abstract: (258) HTML (0) PDF (0.00 ByteKB) (0)

  Modern bridges is symbolled by long-span, light-weight and high-strength, of which the box girder and cable-supported bridges are two important parts. To that point, the corresponding research progress in 2019 of the related theories is summarized by the authors^[1], including the theory of the new box girder with corrugated steel webs and traditional box girder, the interaction between cable and saddle in multi-tower cable bridge, the ultimate load capacity of cable-supported bridges, and application of UHPC technology in cable-supported bridges. A review is made to further understand the research trends of the above five aspects in 2020. In addition, the recent development of the cable-supported bridges is discussed. It is concluded that as the emergency of the new structural forms the refined analysis theory of box girder and cable-supported bridges have new opportunities to extend.

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• State-of-the-art review of bridge maintenance in 2020

  lijun, Wei Xing, Tang Chaoyong, Zhang Bolun

  Abstract: (450) HTML (0) PDF (0.00 ByteKB) (0)

  The purpose of bridge maintenance is to maintain the normal traffic function of the bridge, to meet the requirements of load,speed and other factors, and to prevent sudden and serious disasters. Bridge maintenance has the characteristics of long-term, local and emergency. At present, there are special bridge maintenance institutions at home and abroad, which have formed systems and specifications for daily inspection, regular inspection, special inspection, special inspection, maintenance and reinforcement of bridges. The maintenance contents and key points have been clearly defined and implemented, and the maintenance technology can meet most of the requirements. At present, the outstanding problem is how to achieve rapid maintenance and emergency treatment. High speed railway and urban rail transit are in uninterrupted operation, high-density traffic, and construction is prohibited during traffic. They can only use the skylight time of 0-4 a.m. every day for maintenance, and the line must be opened after 4 a.m. every day. Highway also requires continuous maintenance. After the occurrence of sudden disasters, it needs emergency treatment and maintenance. The maintenance system of railway system makes it easier to collect data and realize data standardization. Bridge maintenance is developing in the direction of rapid maintenance and intelligent maintenance. This paper mainly introduces the research progress of bridge maintenance in 2020 from three aspects: disease and treatment, maintenance strategy and new maintenance technology.

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• Research progress in 2020 of the application of fiber reinforced polymer in bridge structures reinforcement

  Ye Huawen, Tang Shiqing, Duan Zhichao, Liu Jilin, Yang Junchuan

  Abstract: (797) HTML (0) PDF (0.00 ByteKB) (0)

  Fiber-reinforced polymer(FRP) has been widely used in modern bridge engineering and old bridges reinforcement in recent years due to the excellent material properties that can adapt to the development needs of bridge structures towards light weight and durability. In order to promote the development of bridges structures reinforcement using composite materials as well as meet the diversified needs of engineering operation and maintenance, this article reviews the research on the reinforcement characteristics of old bridges, the performance of FRP and the methods of strengthening bridges. The research and application of FRP in bridges reinforcement in recent years is elaborated in detail from two aspects of concrete and steel bridge reinforcement. FRP has become an important bridge reinforcement method because of its obvious strengthening performance and great efficiency. In order to develop and expand its application scope, it is necessary to standardize FRP anchor, promote the monitorability of strengthened bridges and establish a specification system of FRP strengthened bridge structures.

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• State-of-the-art review of seismic design of bridge in 2020

  Zhao Canhui, Jia Hongyu, Yue Weiqin, You Gang, Jia Kang, Zheng Shixiong

  Abstract: (480) HTML (0) PDF (0.00 ByteKB) (0)

  Earthquake may cause great damage to bridge structure, damage and even collapse of bridge. The seismic resistance of bridges has always been an important research direction in the field of bridges. This paper summarizes the research results and development trend of the seismic field of bridges in 2020, and the main conclusions are as follows: the seismic performance of the pier column after replacing ordinary concrete with new materials is explored; The shaking isolation pier has good seismic performance through shaking table experiment and numerical simulation; The displacement ductility and residual displacement of the pier can be improved by using the carbon fiber cloth sheath to strengthen the pier column; The traditional single leg to double limb thin-walled high pier has better seismic performance, the hysteretic curve of the double limb thin-walled pier with high main reinforcement ratio is full, and the energy consumption performance is good, and the axial pressure ratio is improved significantly; The rectangular hollow double column high pier with energy dissipation beam has better energy consumption capacity, bearing capacity and displacement ductility; The system of vibration reduction with friction pendulum support and limit energy dissipation rod has good effect of reducing isolation, and the internal force damping rate can reach more than 20%; The reliability of using new type of unbonded steel mesh rubber support (USRB) instead of unbonded laminated rubber support (ULNR) in bridge is studied; The influence of near field vibration and soil structure interaction on the dynamic response of the bridge is investigated.

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• Test research on corroded RC beams under the influence of different strengthening schemes using steel plate

  Tang Huang, Peng Jianxin, Wang Han

  Abstract: (345) HTML (0) PDF (0.00 ByteKB) (0)

  In order to explore the influence of different strengthening schemes using steel plate on the bearing capacity of corroded RC beams, and the strengthening effect of different strengthening schemes are explored. The characteristics in the bearing capacity, deformation, failure mode and ductility of corroded RC beams strengthening by steel plate with flexural strengthening schemes, shear strengthening scheme and flexure-shear combination strengthening scheme are compared, and the advantages and disadvantages of different strengthening schemes are analyzed. The results show that: for the flexure-strengthened corroded beam which steel plate thickness are 3mm, 4mm and 5mm, respectively, the ultimate bearing capacity of flexural strengthened corroded beams increases by 7-18kN with the increase of steel plate thickness. The effect of combined strengthening is most obvious, and the ultimate bearing capacity increases by 107.7% compared with corroded beams. Combined strengthened corroded beams have the strongest deformation resistance, the followed is flexure-strengthened corroded beams, the increase of steel plate thickness has a positive effect on the deformation resistance of flexure-strengthened corroded beam. The combined strengthening scheme can most effectively improve the ductility of corroded beam than the other two strengthening schemes, the ductility of which is improved by 320.4% compared with corroded beam, followed by shear strengthened corroded beams. The ductility of flexure-strengthened corroded beam is smaller than that of other two kinds of strengthened beams, and which increases first and then decreases with the increase of steel plate thickness. The deformation resistance and ductility should be considered comprehensively when evaluating the strengthening effect of flexure and shear strengthened corroded beams.

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• Analysis of normal section bending bearing capacity of inverted U-Shaped steel-encased concrete composite beam

  yanqiwu, zhangzheng

  Abstract: (285) HTML (0) PDF (0.00 ByteKB) (0)

  In order to study the normal section bending capacity and structural requirements of a new type of inverted U-shaped steel-encased concrete composite beam, nonlinear finite element models of the composite continuous beams have been stablished with the reference of the existing U-shaped steel-encased concrete composite continuous test beams, and the load-mid-span deflection curves of the finite element models of the composite continuous beams have been simulated and compared with the related test results. The rationality and effectiveness of the modeling method and parameter selection of the composite beam finite element models are verified. Based on the finite element model of composite continuous beams, the main influencing parameters of bending capacity of inverted steel-encased concrete composite beams are analyzed. Based on the test and simulation results of normal section bending capacity of inverted U-shaped steel-encased concrete composite continuous beams, a simplified plastic theory is proposed to calculate the normal section bending capacity of composite beam, but the plastic theoretical calculation value of the normal section bending capacity of the composite beam should be multiplied by the modified coefficient of 0.96. The comparison between the plastic theoretical calculation value of the normal section bending capacity of the composite beam and the simulation value of the finite element model of the composite beam shows that the two values are very safe and close, and the modified simplified plastic theory calculation value of the normal section bending capacity of the composite beam is accurate and reliable enough.

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• Engineering test and numerical analysis of underground concrete silo

  JIN Libing, Liang Xinya, Huo Chengding, Wang Zhenqing, Wang Zhen

  Abstract: (529) HTML (0) PDF (0.00 ByteKB) (0)

  The underground granary can take full advantage of the underground space, it has better fireproof, anti-toxicity, explosion-proof and other properties. In the meantime, the underground silo can use the shallow geothermal energy to realize quasi-low temperature storage. With the advantages of energy-saving, low-consumption and grain quality-ensuring, it plays a significant role in ensuring the grain safety and sustainable development of China. This paper adopted the combination of engineering full-scale test and numerical analysis to carry out engineering tests at different construction stages of the large underground concrete silo, and conducted engineering tests and numerical simulation on the mechanical properties of the silo wall at different construction stages to verify the rationality and validity of the numerical analysis method. Furthermore, the mechanical properties of the wall of the most unfavorable working conditions under the combined soil and water pressure were numerically analyzed. The results show that the internal forces of the numerical simulation results of the silo wall were in good agreement with the experimental results, which verified the validity of the numerical method, the radial stress of the silo wall was highest at the bottom of the silo wall, and the hoop stress was highest at about two-thirds of the top of the silo wall. This method can provide reference for the mechanical analysis and structural design of similar underground reinforced structures.

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• Study on Vertical Uplift Resistance of the Foundation of Plate and Ball Connected by Anchor Cable

  wangxuejiao, yanzhixin, longzhe

  Abstract: (483) HTML (0) PDF (0.00 ByteKB) (0)

  In the light of the engineering characteristics of sandy soil foundation in desert area and the shortcomings of existing transmission tower foundation, a foundation of plate and ball connected by anchor cable is developed. This foundation not only fills the gap of transmission tower foundation in desert area, overcomes the construction difficulties of sandy soil foundation, but also meets the requirements of safety and stability of the project. By means of the combination of the similar model uplift test and numerical simulation, the displacement of foundation under different uplift loads is analyzed. And, the effects and the law of influence of buried depth ratio, spherical diameter and column diameter on the ultimate uplift bearing capacity coefficient of foundation and the radius of main rupture surface of soil surface are studied. The results show that the numerical simulation results are in good agreement with the model test results, and the load-displacement curve presents a three-stage change, which corresponds to the three stages of soil deformation evolution. The ratio of buried depth has the greatest influence on the ultimate uplift resistance of foundation, and there is a positive correlation between them. The ultimate uplift bearing capacity coefficient increases first and then decreases with the increase of burial depth ratio, and is negatively correlated with sphere diameter and positively correlated with cement-soil column diameter. The radius of main rupture surface of soil is negatively correlated with the buried depth ratio, spherical diameter and column diameter.

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• State art of biogeotechnology and its engineering implications

  huyingkui

  Abstract: (851) HTML (0) PDF (0.00 ByteKB) (0)

  This paper summarizes biochemical reaction processes and mechanisms of the major microorganisms involved in the field of bio-geotechnical engineering. The researches focus on soil improvement technology, sealing technology, contaminated soil remediation technology are summarized and discussed. Through the collection and summary works on this topic, this paper aim to promote a deeper and more comprehensive fundamental researches and contribute to promotion and application of the bio-technology in geotechnical engineering.

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• Experimental study on the shear behavior of fiber-reinforced bio-cemented sand

  Zheng Junjie, Song Yang, Lai Hanjiang, Cui Mingjuan, Wu Chaochuan

  Abstract: (661) HTML (0) PDF (0.00 ByteKB) (0)

  Microbial-induced calcite precipitation (MICP) has the prominent advantage of significant improving the shear strength of soil,while MICP sand also has the obvious shortcoming of brittle failure． A certain amount of fiber was added into MICP sand in order to improve the brittleness,and based on consolidated drained triaxial compression tests,the shear strength characteristics of fiber-reinforced bio-cemented sand was studied．And then,the effects of fiber content,fiber length and initial relative compactness of samples on the shear characteristics of fiber-reinforced bio-cemented sand were discussed．Finally,the corresponding mechanisms of strength enhancement and ductility improvement were also investigated through scanning electron microscope．The results show that during the process of MICP,calcium carbonate crystals deposited on the fiber surface effectively improve the roughness of fibers surface,while the mixture of calcium carbonate and sand provides anchorage to the fibers,enhancing the shear strength of MICP sand and improving the strain softening characteristic,and it is concluded that fiber has the potential to improve brittleness of MICP sand．

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• Study on Removal of Compound Pollutants in Water by Coagulation - Ultrafiltration Process

  Zhaochun, Jinfan, Anye, Sunzhihua, Zhenghuaili

  Abstract: (393) HTML (0) PDF (0.00 ByteKB) (0)

  The effect of humic acid (HA) on the stability of nano-TiO2 was analyzed, and the effects of coagulant dosage, pH and calcium(Ⅱ) concentration on the removal efficiency of HA- TiO2 composite pollutants by the coagulation-ultrafiltration process were investigated. The results showed that the electrostatic adsorption and coordination reaction occurred between nano-TiO2 and HA in the aqueous solution, which caused the decrease of effective particle size of nano-TiO2, the enhancement of electrostatic repulsion, more uniform dispersion of colloid, the increase of system stability and easy migration. These posed a threat to the safety of drinking water. The optimum parameter for HA-TiO2 composite pollutants removal was that the coagulant concentration is 0.46 mmol/L, and the initial pH value is between 7 and 8. The calcium ion in the solution will lead to the decrease of membrane filtration flux and increase the membrane fouling.

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• Study on heat conduction of fire protection for isolated rubber bearings under fire

  Wang Lan, Wang Lixiong, Zhan Wangyu

  Abstract: (311) HTML (0) PDF (0.00 ByteKB) (0)

  This paper studies the heat conduction limit of fire protection for isolated rubber, and provides theoretical evidence and experimental data for fire protection. Based on one-dimensional unsteady heat conduction, formula under ISO834 standard fire is derived. According to the GB9978.1-2008 fire test, three kinds of components, LNR500, LNR1500 support board fire protection, LNR500 support board with flexible fireproof material fire protection, are tested.Modeling and finite element thermal analysis are carried out on ABAQUS. The numerical analysis and fire test results verified our theory. Based on the derivation and experiment data, when the temperature of the support surface reaches the critical temperature 150 C, the table of the limit thermal conductivity of fireproofing board with different thickness can be referred in engineering applications.

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• Vibration testing and comfort evaluation of floorslabs under pedestrian and escalator loads

  PAN Yi, WANG Shuangxu, GUO Rui, HU Wenhao

  Abstract: (342) HTML (0) PDF (0.00 ByteKB) (0)

  On lap escalator cantilever floor under pedestrians - escalator coupling is prone to lead the problem of vertical vibration, in a commercial laminated cantilever in the floor as the background, take the field vibration test method, the escalator running, the number of pedestrians and pedestrian movement on the influence of the cantilever floor vibration response, and through the test data of floor structure vibration comfort perception evaluation and personnel. The results show that the movement of pedestrian on escalator is the main reason for the vibration of overhanging roof. The vibration of the roof is more obvious in response to the increase of the number of people accompanying it, but decreases with the increase of the length of the escalator. The peak acceleration was used to evaluate the comfort of overhanging roof, and the vibration response of overhanging roof exceeded the comfort limit when pedestrians ran on the escalator. Use KB (Konstant Beurteilungswerte) value to judge the perception of cantilever floor, when the pedestrian relatively static escalators, the vibration of the cantilever floor not beyond the permissible value perception degrees, when pedestrians are relatively escalator when walking or running, the vibration of the cantilever floor would be beyond the permissible value perception degrees; The movement of people relative to escalators does not cause the overhanging roof to resonate.

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• Study on preparation and performance of anti-blocking pervious concrete

  Tang Jing, Zhao Yuting, Liang Meikun, He Binwei, Yu Yiheng, Zeng Lu

  Abstract: (355) HTML (0) PDF (0.00 ByteKB) (0)

  In order to improve the permeable performance of pavement, polymer pervious concrete has been widely used in the construction of sponge city. Special fine sand and epoxy resin were used to prepare permeable materials. The influence of particle size and polymer dosage on the compressive strength and permeable coefficient of permeable concrete were discussed by controlling variable method. At the same time, the simulation experiment of blockage was carried out. Based on the image analysis of the aperture of the permeable concrete, and the properties of the concrete was analyzed by observing the microstructure of the concrete. The experimental results show that with the same particle size, with the increase of epoxy resin content, the compressive strength of the permeable concrete gradually increases, while the water permeability coefficient decreases gradually, When the particle size of aggregate is 0.15-0.3 mm, the compressive strength of permeable concrete appears to increase initialy and then decrease, while the permeable coefficient appears to increase continuously. When the aggregate particle size is 0.15-0 .3 mm and the epoxy resin is 5 % of the aggregate mass, the average porosity of the permeable concrete is 14 %, and the average equivalent diameter is 214um. The aggregate blending ratios with particle sizes of 0.15-0.3 and 0.3-0.6 were 1:1, with a compressive strength of 41.7MPa and a permeation coefficient of 1.7mm/s, showing best performance. After the product blocks four cycles, the permeability attenuation coefficient is less than 20%, and the anti-blockage performance is great.

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• Modal analysis and experimental study of spoke cable-trusses

  WANG ZE QIANG

  Abstract: (540) HTML (0) PDF (0.00 ByteKB) (0)

  Through the modal analysis and test of the 1:10 scale model of 60m circular spoke cable-trusses, the influence of 3 parameters of cable prestress, rise to span ratio and diameter ratio of inner and outer ring on the natural vibration characteristics of the structure were investigated. The results of test and theoretical of the first four order modal were compared and analyzed. It can be seen that: The first, second order vibration modes of the structure are antisymmetric upper and lower vibrations, the third order is the inner ring torsional vibration, and the fourth order is the relative torsional vibration of the inner ring. The frequency error is less than 10%, and the experimental mode of vibration is in agreement with the theoretical mode. The frequencies of the first four modes are all above 10Hz, indicating that the spoke cable truss structure is of low frequency dynamic response, and the natural frequency is small and the distribution is dense. When prestress level of the structure is higher, the modal frequency will increase, and the stiffness will also increase. With the increase of sagittal height, the structural frequency will decrease, and the structure is more prone to lateral instability. With the increase of the inner and outer ring diameter ratio, the torsion stiffness of structure will decrease and torsion instability will also occur.

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• Bond Behaviour Study on Interface between Steel Plate and Bonded Concrete under Hydrothermal Environment

  yaoguowen, liuyusen, wutianyu, lishiya

  Abstract: (318) HTML (0) PDF (0.00 ByteKB) (0)

  The interface performance between steel plate and concrete is the key to strengthened concrete structure. In this paper, there were 27 specimens carried out for steel plate bonded concrete under hydrothermal environment. And accelerated hydrothermal aging was respectively conducted in 5 days, 10 days and 15 days. Then the double- shear test was performed to obtain the ultimate load, strain distribution and relationship of load-displacement during the shear failure process on steel plate-concrete interface. After long term temperature and humidity coupling, the durability of the steel plate-concrete interface was studied. Considering the analysis of bond failure mode, loading process and the relative displacement evolution on bonding interface, the expression of shear stress and slip was proposed, which was related to temperature and humidity. Finally, the bond-slip constitutive model was established in consideration of the temperature and humidity. The numerical simulation results were in good agreement with the experimental results. The results of the paper provide reference for the design of the concrete structure with bonded steel plate and the durability theory.

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• Validation and Revision of Two-node Model in Outdoor Unsteady Environment in Hot and Humid Region

  Jiang Yi, Zhao Lihua, Meng Qinglin, Mochida Akashi

  Abstract: (486) HTML (0) PDF (0.00 ByteKB) (0)

  Because of rapid urbanization and global warming, urban outdoor thermal discomfort and risk of thermal safety increased. In order to find out the physiological parameters changes of human body in outdoor thermal environment, provide a basis for rapid urban thermal environment evaluation, carried out the human thermal response measurement, then analyzed the simulation accuracy and coincidence degree of the two node model, found out that changes of environment which human in and human activity on human physiological parameters. Based on set-point of skin temperature and core temperature, standard human model, temperature of regulation starting, convective heat transfer coefficient, the two-node model was verified and revised, and a new two-node model for predicting outdoor human thermal response was developed.

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• Experimental Study On Effect of Inlet and Outlet Water Temperature On Performance of A Large Temperature Difference Bathing Wastewater Source Heat Pump Unit

  Ma Liangdong

  Abstract: (339) HTML (0) PDF (0.00 ByteKB) (0)

  Bathing wastewater contains a large amount of waste heat. A large temperature difference heat pump unit was proposed to maximize the recovery of heat energy from bathing wastewater by the authors. The rated design conditions of the unit are: the entry and exit temperatures of evaporator side bath wastewater are 30℃ and 6℃, respectively. The inlet temperature of tap water on the side of the condenser is 5℃, the outlet temperature of hot water is 45℃, and the theoretical calculation value of the maximum coefficient of heating performance (COP) is 4.9. In this paper, the effects of inlet temperature of tap water, outlet temperature of hot water and inlet temperature of bath wastewater on thermal performance of heat pump unit were studied experimentally. The experimental results show that the COP of the whole unit is 5.0 under the rated design conditions. When the inlet temperature of tap water increases from 5℃ to 15℃, the overall unit COP was reduced from 5.0 to 3.85. But if the inlet temperature of tap water is less than 10℃, the overall unit COP is higher than 4.5; When the temperature of the hot water outlet changes from 40℃ to 50℃, the overall unit COP gradually decreases from 5.3 to 4.9. And when the inlet temperature of bath waste water rises from 30℃ to 35℃, the overall unit COP rises from 4.8 to 4.95.

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• Tensile test of pultruded GFRP pipe connected with steel pipe

  Zhu Mingqiao, Li Zhibin, wangyao

  Abstract: (301) HTML (0) PDF (0.00 ByteKB) (0)

  Abstract: The reliable connection of pultrusion forming GFRP pipe joints is a prerequisite to ensure the normal operation of the components. In order to research its tensile connection performance, this paper adopts two kinds of connection modes of bonding connection and bolt connection in GFRP pipe and steel pipe connector, and carries out its tensile test research respectively. The distribution characteristics, force mechanism, failure process and the influence of bonding length on load-bearing capacity of glue layer shear stress along the length direction was studied in the adhesive bonding test. The experimental results show that the shear stress of the glue layer is large at both ends and small in the middle along the length direction at the initial stage of loading. As the load increased, the stress gradually shifted towards the loading end of the glue layer. The increase of bonding length can significantly improve the load-bearing capacity of the connecting parts, but when the length reaches 1.6 times of the pipe diameter, the increase of the bonding length is not obvious to the increase of the load-bearing capacity. Therefore, the 1.6 times the pipe diameter can take into account as the effective bond length of the GFRP pipe. The influence of e/d (edge distance/bolt diameter) and bolt row number on the connection load-bearing capacity and failure mode were studied in the bolt connection experiment. The experiment results show that when is equal to 7, the load-bearing capacity reaches the maximum value and the main failure mode is extrusion failure. According to the relationship between the bolt row number and the load-bearing capacity, the corresponding reduction coefficient can be deduced for calculating the load-bearing capacity.

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• Research on active failure and earth pressure of cohesionless soil with limited width behind retaining wall based on DEM

  wanli, zhang xingzhou, WANG Yufeng, XU Liming, XU Changjie

  Abstract: (492) HTML (0) PDF (0.00 ByteKB) (0)

  The classical Coulomb and Rankine earth pressure theories are based on the assumption that the soils near a retaining wall are semi-infinite. It is obviously that these theories are no longer suitable for the narrow backfill behind a retaining wall. A series of numerical simulation are conducted with DEM to study the active failure process of limited cohesionless soil behind a rough or smooth wall. The development of the failure surface, the displacement field of the soils and the distribution of active earth pressure are analyzed. The results obtained from DEM show that multiple slip surfaces occur in the backfill if the soil behind the smooth wall is narrow enough. The slip surface angle is close to the Coulomb’s theoretical solution, which shows no related to the width height ratio. This ratio also has little influence on the active earth pressure in this case. In another case, when the wall is rough, the actual shape of failure surface is a curve rather than a straight line. The rougher the wall, the weaker the reflection. The angle of failure surface decreases along with the width height ratio of soils increases. And the failure surface is finally located inside the Coulomb’s failure surface. There exists a critical width height ratio of soils behind the rough wall. The active earth pressure decreases with the increases of the ratio if it is smaller than the critical ratio, but the active earth pressure is independent with the ratio if it is larger than the critical ratio. The smaller the width height ratio is, the smaller displacement of the ultimate equilibrium state will be, regardless of roughness of the retaining wall.

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• Multi-parameter experimental study on reinforced concrete two-way slab with studs

  JIN YU, YI WEIJIAN, HU LAN, MA KEJIAN

  Abstract: (524) HTML (0) PDF (0.00 ByteKB) (0)

  The main objectives in this paper are to study mechanical performances of reinforced concrete two-way slab with different stud parameters.The experimental study on 7 reinforced concrete two-way slab-column connections with punching shear studs were completed.The main parameters were spacing of stud, the diameter of the stud, the height of the stud, the strength of the stud and the arrangement of the stud.The entire process of damage of slab-column connections with studs was simulated by using static loading method. By comparing and analyzing the test results of specimens with studs,the results show that increasing the diameter of the stud,the height of the stud or the strength of the stud can improve the anti-punching shear performance of the specimen.The increase in diameter is the most obvious, and the increase in deformation is 36%.Increasing stud spacing and reducing stud height are both not good for the improvement of the test, and the load-bearing capacity and the deformation are reduced.By comparing three different stud arrangements it is found that using radiation arrangement with the same number of studs and orthogonal arrangement with increasing the number of studs are both conducive to the improvement of the specimen anti-punching shear capacity,and the former was more economical.And then the reliability of the test results was verified by comparing the calculated results of relevant specifications with the test results.The results show that the safety reserve of specification calculation results of slab-column structure with studs is enough. However,it is not enough to reflect the nature of test results,especially contributions of the stud to anti-punching shear performance of slabs are underestimated.

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• Analysis on end-bearing capacity and end-bearing resistance factor for piles socketed into rocks

  Lu Xianlong, Qian Zengzhen, Yang Wenzhi, Zheng Weifeng

  Abstract: (303) HTML (0) PDF (0.00 ByteKB) (0)

  It is an important issue to investigate the characteristics of end-bearing capacity and to determine the end-bearing resistance factor for the application of rock-socketed piles. In this study, the results of 165 compression load tests were collected to examine several issues related to the end-bearing capacity behavior of rock-socket piles. All these load test results were conducted on different rocks with different rock-socket piled conditions by different authors worldwide. Using these load test data, the type and the uniaxial compressive strength of rock in nature, the diameter and the embedment depth of socketed piles, the ultimate end-bearing resistances were compiled. The ratio of ultimate end-bearing capacity to unconfined compressive strength of the rock was defined as the end-bearing resistance factor of rock-socketed piles. Effects of the pile diameter, the pile depth rocked into rock, the ratio of rocketed depth to diameter, and the unconfined compressive strength of the rock on the ultimate end-bearing capacity and the end-bearing resistance factor were comprehensively investigated. An empirical relation between the unconfined compressive strength and the end-bearing capacity as well as the end-bearing resistance factor were suggested, which could be used in the design for rock-socketed piles.

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• Multi-parameter Simulation Method of Semi-Rigid Node of Steel Tubular Scaffold with Couplers

  Xie Xiangyang, Chen Guo, Yin Lei

  Abstract: (286) HTML (0) PDF (0.00 ByteKB) (0)

  Upright tube’s 6 degrees-of-freedom are constrained by horizontal tube and diagonal brace at the coupler connection joint, the strength of such constrains is the key factor of the stable bearing capacity of the scaffold. To determine the efficiency of the constraints, single factor sensitivity analysis and eigenvalue buckling analysis methods are applied to measured each constraints’ contribution on stable bearing capacity. The efficiency analysis results of their contributions indicated the mechanism of constraints and then horizontal tubes and bracing tubes. Reasonable effectiveness of 6 constrains is tentativly researched according published experimental data of couplers, and then a multi-parameter simulation method of semi-rigid node is proposed. The premise condition of the multi-parameter simulation method is validated by the comparison between the experimental loads and the the inner forces’ calculating results of the couplers, in which effective length method and linear elastic second-order analysis method is adopted. Accompanying with the research of multi-parameter simulation method,some common deficiencies or limitations of ordinary methods which are based on single parameter assumption are listed and analyzed.

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• Preparation of Multiwalled Carbon Nanotube/Cuprous Oxide Composite Microsphere and its Photocatalytic Property for N-formylmorpholine(NFM) wastewater

  CHE Chun-bo, ZUO Jin-long

  Abstract: (378) HTML (0) PDF (0.00 ByteKB) (0)

  Multiwalled carbon nanotubes/cuprous oxide (MWCNTs/Cu2O) composite microsphere was fabricated by liquid phase reducing method. The analysis of functional group, phase and morphology on the samples were characterized by IR, SEM and XRD. The results showed that MWCNTs were combined with Cu2O to form composite microsphere by vertical and horizontal interspersing. Compared with pure Cu2O, MWCNTs/Cu2O composite catalyst has more excellent catalytic effect for target organic N-formylmorpholine(NFM) wastewater.

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• Optimization of Photopolymerization CMCTS-g-CPAM by Response Surface Methodology and Evaluation of Sludge Dewatering Performance

  Zhu Hui, Sun Wenquan, SUN Yongjun, Zheng Huaili, Tang Mengdan

  Abstract: (372) HTML (0) PDF (0.00 ByteKB) (0)

  Excess sludge, product of sewage treatment, is increasingly produced. Sludge decontamination is required before sludge disposal, and sludge conditioning is a very important step. Cationic sludge dehydrating agent of CMCTS-g-CPAM was synthesized using Carboxymethyl chitosan (CMCTS), acrylamide (AM) and methacryloyloxyethyltrimethylammonium chloride (DMC) as monomers, azobisisobutylphosphonium hydrochloride (V-50) as an initiator through initiating polymerization by ultraviolet light. The preparation conditions of CMCTS-g-CPAM sludge dehydrating agent were optimized by response surface methodology (RSM) taking the photoinitiator concentration, pH and illumination time as the object of investigation, the intrinsic viscosity of CMCTS-g-CPAM as the response value. The optimal illumination time, photoinitiator concentration, and pH of respectively 2h, 0.04% (volume fraction), and 9 were obtained by response surface analysis. FT-IR and 1H-NMR of the graft copolymer indicated that AM and DMC were successfully grafted to CMCTS. Finally, the synthesized product was applied to sludge dewatering. The experimental results showed that it has good sludge dewatering performance. Sludge specific resistance decreased to 1.96&amp;#215;1013m/kg, and the moisture content of the filter cake decreased to 79.28%,at the flocculant dosage and pH of 30mg/L and 10, respectively.

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• Dynamic performance of closed heat source tower in winter non – frosting conditions

  jiayuhao, linianping, cuihaijiao, zhangnan

  Abstract: (247) HTML (0) PDF (0.00 ByteKB) (0)

  In order to investigate the heat transfer process in closed heat source tower under the non-frosting condition, the finite difference method was adopted to develop the dynamic heat and mass transfer model. Comparing the calculated results with the experimental findings, the root mean square error of the outlet solution temperature is 0.201 °C. Through experiments and simulations, dynamic performance of the closed heat source tower during variable load operation are analyzed, results show that the closed heat source tower, as a heat source, can provide solution with relatively constant temperature for heat pump when working condition changed, in addition, compared with traditional air source heat pumps, the closed heat tower has lower frost risk in the low temperature and high humidity environment.

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• TheSanalysisSof mechanical properties of multiple-structure thick overburden pervious foundation based on fluid-solid coupling

  WANG Zheng-cheng, MAO Hai-tao, LONG Shun-jiang, JIANG Hai-bo, ZHANG Ru-yi

  Abstract: (662) HTML (0) PDF (0.00 ByteKB) (0)

  The mechanical properties of every soil layer in multiple-structure thick overburden pervious foundation diverge significantly and specific problems that draw attention are diverse in range, which requires further study. This paper derived from the principle of Biot consolidation theory takes into account soil non-liner rheological and the change of porosity, permeability coefficient, elastic modulus and poisson ratio at the consolidation deformation process of soil. The coupling process of seepage and stress fields of Daga hydropower station dam foundation is simulated by fluid-structure interaction module of ADINA to analyze mechanical properties and interaction of each layer. The research shows that the looser permeable soil on surface is the main seepage channel, inlet and outlet area of seepage and settlement deformation reflects area, and measures should be taken to improve the compression modulus in upstream and install the anti filter layer and drainage facilities in downstream area. Fine sand layer in dam foundation is the main reason of dam foundation settlement, which plays a leading role in dam foundation settlement, at the same time, attention should be called to the liquefaction properties of adverse impact on the dam foundation. Artesian aquifer in dam foundation produce up-holding force on the downstream side of the upper structure, and the destruction is small if the location is deep. Deep soil layer have a less effect on seepage failure of dam foundation, but the effect can not be dismissed on settlement and seepage flow. Since in the permeability coefficient of sand gravel stratum and fine sand layer exists a modest distinction, the soil layer does not generate the contact erosion. In addition, the most of pore water pressure is dissipated at rapidly-declining phase, dam foundation shows a tendency of stability at rapid consolidation stage. Vertical cutoff wall can effectively decrease seepage gradient and seepage discharge, and the settlement deformation of dam foundation is controlled in upstream region of cuttoff wall. But the deformation of upstream dam foundation produce a large horizontal thrust to cutoff wall, so the size of cutoff wall should be increased or auxiliary seepage control measures adopted to contain that.

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• Influence of Summer Dressing Behavior to Office Building Air-conditioning Energy Consumpution in Beijing-Tianjin Regions

  lisha, Qian Xiaoming, Yang Ruiliang

  Abstract: (238) HTML (0) PDF (0.00 ByteKB) (0)

  Dressing-behaviour affect building air-conditioning energy consumption by indoor air parameter. Energy consumption simulation software DEST is used , the energy consumption of operating and expectation parameter is lower 10.86% and 13.16% of the recommended standard parameter in Beijing-Tianjin regions. While it is lower only 4% to the experimental thermal property of typical dressing behavior.It stated the subjective temperature related with thermal resistance need amendment by the dressing behavior of region. The model of dressing behavior adjust office building Air-conditioning Energy Consumpution is given. Energy saving rate of dressing behavior isεc, Energy saving ifεc is negative,on the contrary there is no energy saving. The critical thermal resistance is 0.563clo when energy saving rate is 0 in Beijing-Tianjin Regions. The premise of energy saving is thermal resistance of dressing lower than The critical value in the design and operation of air-conditioning system. The model of dressing behavior offer quantitative criteria of style and fabric in region, supply a method to accuracy control energy consumption.

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• Study on Safety Risk Assessment Method for Road Slope in Western Hubei Mountain Region

  Luo Hongming

  Abstract: (405) HTML (0) PDF (0.00 ByteKB) (0)

  The realistic needs of mountainous highway construction in China are explored and studied on risk problem, which is inevitably exist in the mountain highway construction, otherwise, safety risk assessment of mountainous highway slope has important theoretical and practical significance. Highway slope safety risk prediction and evaluation methods are established which based on geological hazard risk assessment methodology. Safety risk assessment for Taishangou tunnel entrance slope of Shiyan to Baihe highway is studied by risk evaluation method of geological hazard. Monte Carlo simulation is used to get the stability of the slope probability of failure under the conditions of normal operation and abnormal conditions. And the vulnerability for the part of slope within the affected areas is analyzed. Possible economic loss and population casualties are obtained through the risk calculation formula. The results show that: Taishangou tunnel entrance slope is less risk in the natural conditions under the conditions of the acceptable range class; but slope is higher risk in non-normal conditions, management measures must be taken to reduce risk and to strengthen monitoring, particularly to strengthen the monitoring of slope deformation in the construction process and adverse natural conditions. The result is provided guidance for slope protection and safe operation of Shiyan to Baihe highway.

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Volume 48,2026 Issue 1

Environmental Engineering

• Validation and revision of two-node model in outdoor unsteady environment in hot and humid region

  Jiang Yi, Zhao Lihua, Meng Qinglin

  2020,42(1):168-179, DOI: 10.11835/j.issn.2096-6717.2019.158

  Abstract: (1328) HTML (1572) PDF (9.51 MKB) (49965)

  Rapid urbanization and global warming aggravate the thermal discomfort of urban outdoor environment and increase the risk of thermal security. In order to find out the physiological parameters changes of human body in outdoor thermal environment, provide a basis for rapid urban thermal environment evaluation, an outdoor experiment was carried out to observe the thermal response of human body. Based on the measured data, the simulation precision analysis and coincidence test of the two-node model were carried out. It is found that human skin temperature and body core temperature show different trends under the influence of outdoor wind speed, MRT and self-regulation, in order to ensure the simulation accuracy, the two-node model of human body needs to be modified from the following four aspects:skin and core temperature, standard human model, temperature of regulation starting, convective heat transfer coefficient, relevant parameters and calculation process shall be written as assignable variables or mathematical expressions, the revised two-node model is universal and applicable to the prediction of outdoor human thermal response.

• Analysis of Hysteretic Performance of C-section Specimens of Cold-formed Steel

  YANG Na, PENG Xiong, YANG Qing-shan

  2012,34(2):69-76, DOI: 10.11835/j.issn.1674-4764.2012.02.012

  Abstract: (6969) HTML (0) PDF (10.08 MKB) (31536)

  Seven specimens were loaded with axial force and horizontal cycle force to analyze the hysteretic performance and the influencing factor as well. The influence of axial compression ratio and aspect ratio on the hysteretic performance was investigated, including the buckling behaviors and the energy dissipation. And the positive role of combined effects on the hysteretic performance of cold-formed specimens was studied emphatically. The experiment reveals that a large axial compression ratio incurs a serious decrease on hysteretic performance, while the combined effects give an increase on it. In addition, the numerical mode is set up. Considering double nonlinearity, the results of experiment and simulation match each other well. Based on the data, it is obtained that local buckling plays a great negative role during the loading course. At last, the characteristics of hysteretic performance of cold-formed steel specimens are concluded and some suggestions are given.

Environmental Engineering

• Recent advances in electro-oxidation technology for water treatment

  ZHOU Yujun, JI Qinghua, HU Chengzhi, QU Jiuhui

  2022,44(3):104-118, DOI: 10.11835/j.issn.2096-6717.2021.160

  Abstract: (2002) HTML (3798) PDF (3.19 MKB) (12257)

  Electro-oxidation technology, as one common seen electrochemical water treatment technology, can effectively address the problems in which conventional water purification technology cannot or cannot easily solve.It has becoming a promising strategy for its extraordinary features and advantages, especially in ultra-low discharge requirements of water treatment. The development of electro-oxidation technology enriches green catalytic oxidation system and is of great scientific significance for constructing "carbon neutral" water treatment technology. In the past ten years, electro-oxidation technology has drawn increasing attention and achieved great progresses.In aiming of aqueous pollutants removal, resource and energy recovery from wastewater, numerous studies focused on the design and modification of functional electrode materials, as well as exploiting efficient reactors. In this review, the mechanism and research progresses of electro-oxidation water treatment technology were systematically discussed. A conclusion on its future development was summarized.

• Recent advances and overview on sustainable development of membrane-based wastewater treatment technology

  WANG Zhiwei, DAI Ruobin, ZHANG Xingran, WEN Yue, CHEN Mei, LI Jiayi

  2022,44(3):86-103, DOI: 10.11835/j.issn.2096-6717.2021.155

  Abstract: (1203) HTML (2761) PDF (7.72 MKB) (11957)

  The development of membrane-based wastewater treatment technology faces two challenges, i.e.:(i) improvement in the environment quality requires high-standard treatment, and (ii) carbon emission peak and carbon neutrality calls for green and sustainable techniques. Under such circumstances, methods to break the bottleneck of water permeability and pollutant removal efficiency trade-off, to reduce the energy consumption and carbon emission of membrane technology, and to stimulate the sustainable development of membrane-based wastewater treatment are of great significance.Recently, remarkable progress in membrane-based wastewater treatment has been achieved in terms of membrane separation fundamentals, antifouling membrane preparation, membrane process innovations, and engineering applications. Current efforts have been dedicated to precise design of membrane materials, functionalization of membrane interface, and process greening transformation. In this work, recent research progress has been reviewed in terms of functional extension of membrane technology/process, design of high-performance membrane materials, sustainable utilization of membranes, and green development of membrane processes. Further analysis and discussion on future development are also presented.In the context of future multi-target needs, multi-functionalization, selective and customized separation, and green development are worthy of in-depth research for promoting the sustainable evolution of membrane-based wastewater treatment technology.

Digital Twins and Intelligent Construction

• Applied research status and prospects of artificial intelligence in civil engineering field

  LIU Hongbo, ZHANG Fan, CHEN Zhihua, WANG Longxuan

  2024,46(1):14-32, DOI: 10.11835/j.issn.2096-6717.2022.016

  Abstract: (4785) HTML (875) PDF (4.96 MKB) (10434)

  Artificial intelligence is the core driver of the next generation of industrial change. It is an important method to comprehensively improve digitalization, automation, informatization, and intelligence in the field of civil engineering. To gain a comprehensive understanding of the development and application of artificial intelligence in civil engineering. The basic research areas of artificial intelligence are analyzed qualitatively. The current research status of artificial intelligence in civil engineering design, manufacturing, and maintenance phases is quantitatively analyzed. The CiteSpace visualization tool is used to dig deeper into the problems, development bottlenecks, and research trends of artificial intelligence in civil engineering, and give corresponding solutions and research ideas. The review of the literature found that a significant amount of artificial intelligence research has been conducted in the field of civil engineering. However the development of intelligence has been uneven at various stages, and there are limitations in practical applications. Therefore, it is necessary to deeply explore the cross-integration of intelligent technologies such as neural networks, big data, and deep learning in the full life cycle of civil engineering. To promote the synergistic development of artificial intelligence research in the field of civil engineering.

建筑材料

• Influence factors of normal bonding properties between mortar and mechanical pressing raw-soil brick

  Wang Yihong, Shi Dan, Zhong Jiqing, Shi Yixia, Liu Qiji

  2018,40(1):78-82, DOI: 10.11835/j.issn.1674-4764.2018.01.011

  Abstract: (1886) HTML (1696) PDF (1.05 MKB) (9768)

  In order to investigate the influence factors of normal bonding properties between mortar and mechanical pressing raw-soil brick, the tensile bond strength test was made between mortar and mechanical pressing raw-soil brick with different interfacial condition.There were 72 specimens in total and three ages including 7d, 14d and 28d.The failure mode and the change rules of normal adhesive strength in different ages between raw-soil brick and mortar were explored. The influence of interfacial condition and ages on normal adhesive strength and failure mode was studied. The results show that interfacial condition and ages both have an influence on normal adhesive strength, which is improved along with ages and is decreased because of roughing. The normal bonding properties between mortar and mechanical pressing raw-soil brick is impacted by the type of mortar evidently. The reference for engineering application of raw soil mechanism brick is provided by the research results.

• State-of-the-art review of bridge informatization and intelligent bridge in 2020

  ZHAO Tianqi, GOU Hongye, CHEN Xuanying, LI Wenhao, LIANG Hao, CHEN Zihao, ZHOU Siqing

  2021,43(S1):268-279, DOI: 10.11835/j.issn.2096-6717.2021.230

  Abstract: (3354) HTML (0) PDF (8.80 MKB) (8998)

  With the advent of digital era characterized by informatization and intelligence, the development and innovation of bridge engineering technology are promoted. It is necessary to integrate cloud computing, big data, artificial intelligence, 3D printing, robot and other strategic emerging industrial technologies with bridge engineering, and promote the industrialization, digitization and intelligent upgrading of bridges from multiple dimensions such as intelligent design, construction, operation and maintenance. This paper reviews related frontier technologies and important achievements worldwide in 2020, with regard to bridge informatization, intelligent inspection, safety operation and maintenance, intelligent disaster prevention/mitigation, intelligent materials, and summarizes the research hotspots and prospects. According to the review, BIM technologies can improve the refinement of bridge forward design, the accuracy of construction process control and management. Intelligent inspection technologies (e.g. UAV and robots)and artificial intelligence technologies (e.g. machine learning and convolution neural network)improve the accuracy and efficiency of bridge inspection and monitoring. Applications of high-performance intelligent materials promotes the self-perception, self-adaptability, self-adjustment and self-diagnosis of bridge. Natural disaster monitoring and early warning based on artificial intelligence (AI)provides new development idea for bridge intelligent disaster prevention. To conform to the development trend of informatization and intelligence, future research should deeply integrate artificial intelligence technology into the whole life cycle of bridge design, construction and maintenance to realize the dream of bridge power.

• Influence of seismic fortification intensity for multilayer concrete structure performance

  Jia Huina, Yue Gaowei, Jia Liwen

  2012,34(Z1):116-119, DOI:

  Abstract: (5866) HTML (0) PDF (5.03 MKB) (8909)

  For multilayer concrete structure, the seismic ability of the ground floor column is very poor, improving the seismic fortification intensity of structure is adopted in this paper, the axial force, shear and moment of beam and column are calculated and analyzed in seven degree and eight degree seismic fortification intensity. Numerical results show that with improving the fortification intensity of the structure, the axial force, shear and moment of beam and column increase and the change of the ground floor is the most prominent. In earthquake the destruction of the structure mainly happens in the ground floor column, so this problem is solved fundamentally with increasing fortification intensity in architectural design.

• State-of-the-art review of advances in the implementation of UHPC-OSD system in 2020

  XIA Song, CHEN Liu, YANG Xu

  2021,43(S1):175-184, DOI: 10.11835/j.issn.2096-6717.2021.218

  Abstract: (1298) HTML (0) PDF (1.38 MKB) (8637)

  Ultra High Performance Concrete (UHPC)is combined with the Orthotropic Steel Deck (OSD)in a lot of projects nowadays. That is a typical example of the implementation of new materials and new structures in bridge engineering. Benefitting from its high stiffness, UHPC slab can evidently reduce the local deformation of OSD. In this way, we can greatly reduce the fatigue stress amplitude and the fatigue resistance is increased. In the present work, we reviewed the research advances on the composite UHPC-OSD system from five aspects: the new structures, the shear connectors, the basic static behaviors of the composite deck, the fatigue performance of the composite deck and the basic mechanical properties of UHPC or UHPC members. Most of the concerned literature was published in 2020 or 2021. However, some works reported in a few other recent years were still mentioned in the present work.

• State-of-the-art review of prefabricated concrete bridge structures in 2020

  XU Ziyi, ZHANG Ziyang, XU Tengfei

  2021,43(S1):288-296, DOI: 10.11835/j.issn.2096-6717.2021.232

  Abstract: (1652) HTML (0) PDF (5.47 MKB) (7712)

  Prefabricated bridges have became an important development direction of bridge construction due to the advantages of good construction quality, low impact on the environment, short on-site operation time, and high level of construction safety. Prefabricated concrete bridges are not only suitable for urban road bridges with complex traffic, but also for railway bridges in difficult construction environments. This paper sorts out the research progress of prefabricated concrete bridges at home and abroad in 2020 through the method of literature analysis. According to the types of bridge structure, new technologies, new structures and typical engineering applications in this field are discussed from two aspects: the upper structure and the lower structure. After a rough summary in this article, in the superstructure, the connection structure, crack resistance and durability of the nodes have received extensive attention from scholars; in the substructure, as the prefabricated system is applied to the bridge in the high-intensity earthquake area, the structure and seismic performance of prefabricated bridge piers are currently hot research topics. The durability and crack resistance of the substructure still need to be improved.

• State-of-the-art review of bridge impact research in 2020

  LIU Zhanhui, LU Zhimou, ZHANG Rui, YAO Changrong, LI Yadong

  2021,43(S1):242-251, DOI: 10.11835/j.issn.2096-6717.2021.227

  Abstract: (1294) HTML (0) PDF (1.32 MKB) (7567)

  Bridge impact is a key problem for existing bridges and bridges under construction for a long time. The research on impact and protection problems meets the needs of development. In recent years, scholars have paid more and more attention to bridge impact, and conducted a lot of researches. Following the New Progress and Prospect of Bridge Impact Research in 2019, the author continues to summarize the progress in 2020 in three aspects, such as bridge ship collision, rockfall impact and vehicle collision bridge. Among them, for the bridge ship collision problem, the new code clearly proposes that the main structure of highway bridge should adopt the performance-based anti-collision design method. In 2020, sand mining vessel collision accidents, the broken of Yaxi high-speed bridge, and many vehicle bridge collision events have occurred. This paper sortes these bridge impact events, analyzes and summarizes the relevant achievements in the past year according to personal understanding, and then puts forward the problems that need to be further considered in the future research.

• Generalized Damage Reliability and Sensitivity Analysis on Rolled-Concrete Gravity Dam

  WANG Ya-jun, ZHANG Wo-hua, ZHANG Chu-han, JIN Feng

  2011,33(1):77-86, DOI: 10.11835/j.issn.1674-4764.2011.01.014

  Abstract: (2538) HTML (0) PDF (12.61 MKB) (7283)

  Based on fuzzy self-adapting stochastic damage model, the characteristics of generalized damage stress field on material crack tip are studied. The results express that the numerical algorithm is reliable. Sensitivity of rolled-concrete gravity dam under fuzzy-stochastic damage gaining is implemented by considering the spatial variation of material parameters. It is found that the compression strength of rolled-concrete is the governing index on gravity dam reliability. The activation simulations on fuzzy self-adapting stochastic damage model were carried by adopting different fuzzy distributions, which indicated the governing characteristics of the distribution on generalized damage evolution of rock-like material.

• State-of-the-art review of seismic design of bridge in 2020

  ZHAO Canhui, JIA Hongyu, YUE Weiqin, YOU Gang, JIA Kang, ZHENG Shixiong

  2021,43(S1):91-99, DOI: 10.11835/j.issn.2096-6717.2021.209

  Abstract: (1868) HTML (0) PDF (9.49 MKB) (6941)

  Earthquake may cause great damage to bridge structure, damage and even collapse of bridge. The seismic resistance of bridges has always been an important research direction in the field of bridges. This paper summarizes the research results and development trend of the seismic field of bridges in 2020, and the main conclusions are as follows: the seismic performance of the pier column after replacing ordinary concrete with new materials is explored; The shaking isolation pier has good seismic performance through shaking table experiment and numerical simulation; The displacement ductility and residual displacement of the pier can be improved by using the carbon fiber cloth sheath to strengthen the pier column; The traditional single leg to double limb thin-walled high pier has better seismic performance, the hysteretic curve of the double limb thin-walled pier with high main reinforcement ratio is full, and the energy consumption performance is good, and the axial pressure ratio is improved significantly; The rectangular hollow double column high pier with energy dissipation beam has better energy consumption capacity, bearing capacity and displacement ductility; The system of vibration reduction with friction pendulum support and limit energy dissipation rod has good effect of reducing isolation, and the internal force damping rate can reach more than 20%; The reliability of using new type of unbonded steel mesh rubber support (USRB) instead of unbonded laminated rubber support (ULNR) in bridge is studied; The influence of near field vibration and soil structure interaction on the dynamic response of the bridge is investigated.

土木工程

• Nonlinear behavior of pilesunder inclined and eccentric loads indouble layered soils by model test

  Li Weizhe, Lou Ping

  2018,40(1):68-77, DOI: 10.11835/j.issn.1674-4764.2018.01.010

  Abstract: (1661) HTML (1709) PDF (2.23 MKB) (6937)

  A new hyperbolic p-y curve was derived to generally simulate then onlinearity of piles in layered soils, and the new p-y curve was presented containing parameters such as the initial ratio of elastic foundation coefficient, the initial elastic foundation coefficient,characteristic value of lateral displacementfor soils, and etc.. Model test of six timber piles and two steel piles in two groups settled in layer soils with upper clay and lower sand were done. The calculated lateral displacements of model piles both at the top and at the ground are consistent with the test values by p-y curve method, and the new hyperbolic p-y curve is verified. While the characteristic value of lateral displacement for layered soils increases, the displacement and the maximum bending moment of the pile decrease, the maximum shear and the maximum soil pressure around the pile increase. The variety of characteristic value of lateral displacement for the lower sand has extremely small effect on mechanical property of the pile, then the characteristic value of lateral displacement for lower soils can be defined as the same as that of the top soil during engineering application.

• State-of-the-art review of bridge assessment and reinforcement in 2020

  ZHANG Fang, ZHANG Kaiquan, DENG Jiechao, YANG Qian, WEI Xiang, HUANG Junhao, GONG Wanting, XU Wangxi, QIAN Yongjiu

  2021,43(S1):152-166, DOI: 10.11835/j.issn.2096-6717.2021.216

  Abstract: (1023) HTML (0) PDF (8.96 MKB) (6932)

  Due to the contradiction between the demand of bridge construction brought by the rapid economic development and the backward technical reserve in the period of large-scale construction, China will face the increasing pressure of bridge maintenance in the next 10-30 years. Based on the latest research progress in the field of bridge evaluation and reinforcement, this paper introduces the chemical and physical methods of the main bridge disease monitoring technology, the bridge health monitoring technology and equipment including sensor technology and signal processing technology; The bridge health evaluation method based on time-varying reliability theory and historical data is compared, and the significance of structural parameter inversion relative to artificial intelligence is discussed; The partial reinforcement methods for bending, shearing and seismic resistance, the integral reinforcement methods for additional structural systems, and the electrochemical chlorine removal technology are introduced. The decision-making methods of maintenance and reinforcement of network level and project level are introduced. Considering the cross-disciplinary characteristics, some advanced sensors, signal processing technology and evaluation theory are also introduced in order to clarify the internal logic, and it may be able to play a certain inspiration and train of thought inspiration.

• Embodied energy of wastewater and energy consumption and saving in its treatment processes

  Wei Chaohai, Zhou Hongtao, Huang Jing, Wei Cong, Yang Xingzhou, Wei Jingyue, Li Zemin, Hu Yun, Ren Yuan

  2019,41(5):151-163, DOI: 10.11835/j.issn.2096-6717.2019.106

  Abstract: (1236) HTML (3688) PDF (2.60 MKB) (6548)

  Wastewater treatment is a complex process with high energy consumption and low efficiency. Different from the traditional concept of wastewater treatment, the pollutants contained of wastewater can be regarded as energy materials or as the raw materials of other products to be havested to reduce the energy consumption. The forms of the pollutants' embodied energy in wastewater were examined by employing two calculation methods and taking sewage and coking wastewater as examples. Moreover, two possible path ways for the utilization and maximization of the recovery of embodied energy during the wastewater treatment were discussed. The different forms of energy consumption and their causes in wastewater treatment process were analyzed based on thermodynamic laws and quality characteristics of the wastewater, with reasonable assumptions. The laws of energy transfer and distribution of two specific cases are expressed by the energy flow diagram. Some possible energy-saving approaches and wastewater treatment methods in the future are predicted by comparing different energy saving technologies. Based on in-depth understanding of the embodied energy in wastewaters, valuable elements such as nutrients (nitrogen, phosphorus) and heavy metals can be separated and recovered, and water resources can be reused by combining with related industries and technologies. Therefore, the goal of energy saving can be achieved by the indirect compensation of energy consumption in the wastewater treatment process.

• Whole-body Vibration Perception Thresholds

  YANG Yi-qian

  2012,34(Z2):54-60, DOI:

  Abstract: (2820) HTML (0) PDF (7.65 MKB) (6490)

  This paper aims at providing a basic state-of-the-art of standards and guidelines, as well as laboratory and field studies dealing with whole-body vibration perception thresholds, and comparative analysis is given. Mechanisms of vibration perception, absolute thresholds of perception, difference thresholds and descriptors are introduced. The effects of frequency, posture, direction, duration, gender, age and noise on whole-body vibration perception thresholds are reviewed. And the problems requiring further investigation are proposed.

• Application and Simulation of HVAC Energy saving ControlSystem by Least Enthalpy Difference

  YAN Fei, LIANG Yi, HAN Ning

  2010,32(5):65-70, DOI: 10.11835/j.issn.1674-4764.2010.05.012

  Abstract: (2701) HTML (0) PDF (6.33 MKB) (6469)

  In the process of air conditioning, not only the thermal comfort but also energy saving should be considered. A method, which combines a least enthalpy difference（LED） and mixing air ratio based on the theory of enthalpy, can help to approach to comfortable zone for the air before coming into air handling unit (AHU). Then several mathematic equations of mixing process were derived based on laws of conservation of mass and energy. Eventually, the models of HVAC were established under SIMULINK environment. And the control strategies are validated in the aspects of improving comfortable effect and saving energy. It is found that LED based PID controller can achieve the requirements of better thermal comfort and energy efficiency.

• Productivity and Physiological Response of Students Subjected to Fluorescent Lamps With Different Colour Temperatures and Luminance Level〖JP〗

  YAN Yonghong, GUAN Yang, LIU Xiangde, LIU Wei

  2010,32(4):85-89, DOI: 10.11835/j.issn.1674-4764.2010.04.017

  Abstract: (4690) HTML (0) PDF (5.44 MKB) (6162)

  The influence of luminance level on students’ productivity, asthenopia (an eye strain), and brainfag (a mental exhaustion and depressive disorder) was studied with three typical colour temperatures of T5 fluorescent lamps. The changing rate of productivity and asthenopia were measured by using anomalistic distance determination and Анфимов alphabet test method and the changing rate of productivity was regarded as the brainfag index. It is found that medium colour temperature fluorescent lamps with appropriate exposure time can produce desirable consequences, stimulate the subjects’ cognitive ability and enhance their productivity. However, some lamps with lower or higher colour temperature produced undesirable consequences. The optimal luminances levels were thus variable and correspond to the colour temperature of lamps. The worst combination of colour temperature & luminance was identifies and should be avoided in classroom lighting design.