Abstract:Traditional reliability analysis of slope is often performed under linear Mohr-Coulomb (M-C) failure criterion assumption and using limit equilibrium method or finite element method which is for calculating the safety factor. However, the failure criterion of geomaterials is nonlinear. In this paper, upper bound reliability analysis of slope is performed using upper bound limit analysis and Monte Carlo simulation based on nonlinear Mohr-Coulomb failure criterion, which is for a more practical description of the failure mechansim of geomaterials and obtaining strictly accurate answers. When the nonlinear parameter m is equal to one, the expressions in this study convert into linear Mohr-Coulomb failure criterion, and thus the feasibility of this study is verified by comparing with other results. Meanwhile, initial cohesion, internal friction angle arctan(c₀/σ_t) and nonlinear parameter are selected as the stochastic parameters which are considered to have a truncated normal distribution, and the effects of variability and sensitivity of parameters are analysed. The results show that reliability of slope decreases with the variability of initial cohesion, internal friction angle arctan(c₀/σ_t) and nonlinear parameter; reliability of slope increases with initial cohesion and internal friction angle arctan(c₀/σ_t), and decreases with nonlinear parameter.

Abstract:Under the slope failure criterion based on the breakthrough of the plastic zone, the mutation of displacement increment of slope and calculation convergence, strength reduction FEM and gravity increase FEM are used to analyze the stability of simple slope. Studies indicate that it is accurate to regard the mutation of displacement increment of slope as slope failure criterion; slope safety factor for different strength parameters based on the criterion of mutation of displacement increment is more stable than based on the other two failure criterion. According to three failure criteria, the breakthrough of the plastic zone, the mutation of displacement increment of slope and calculation convergence, the potential slip surface is in turn to develop in depth, and the safety factor of the slope is increased in turn.

Abstract:The uplift bearing capacity of the spread foundation is determined by not only soil physical and mechanical characteristics but also its geometry shapes and scales. The foundation size parameters to determine the minimum quantity of concrete, and the maximum uplift bearing capacity, are key to optimize the foundation design. In order to study their effect on the uplift bearing capacity of the foundation, the undisturbed soil spread foundation in Gobi gravel soil is took as the case. Nine full size test foundations are designed, which use orthogonal test method selected column diameter, the extension angle of the foundation foot and the depth-to-width ratio as influencing factors and the uplift bearing capacity of the foundation as examining goal. The in-site static load tests are carried out in the Gobi gravel soil located northwest China. Load-displacement curves of nine test foundations are obtained and the uplift bearing capacity corresponding are concluded. An index named gradual change ratio is proposed to expressing plastic deformation characteristic of soil foundation under pull load. Meanwhile, the results of the tests show that the sensitivity sort of these geometry factors on the uplift bearing capacity is the depth-to-width ratio, column diameter, and the extension angle of the foundation foot. The conclusion achieve in this work is that adding the depth-to-width ratio in foundation design is an effective measure for improving the uplift capacity of the spread foundation in Gobi gravel soil.

Abstract:Five-star-shaped-pile is a new type of cross section special shaped pile, which is formed by cutting five circular arcs in a circle pile. Five-star-shaped-pile is divided into two categories according to the nature of its cross section, the circumference of the maximum of five star shaped piles F₁ and the perimeter area ratio of the maximum of the five-star pile F₂. The experimental research on the comparison of four single piles in dry sand by sand pouring method is carried out to explore the horizontal bearing capacity of five-star-shaped piles. Similarity ratio is 1:8. These four single piles are:Maximum ratio of perimeter and area of the five star shaped pile F₁,the maximum of the circumference of the five star shaped pile F₂,round pile C₁ with the same section of F₂, round pile C₂ with the same cross-sectional area of F₂. The test results show that:1) the horizontal bearing capacity of F₂, C₁ and F₁ are near, but the section area of F₂ is the minimum, and it is only 0.44 times of C₁; 2) the horizontal bearing capacity of F₂ is 1.63 times of C₂, so it is concluded that the reasonable section form can improve the horizontal bearing capacity; 3) the moment distribution of four single piles is largely consistent, and the moment reach the maximum at 0.4 m; but the section of five-star-shaped pile is small, and the bending stiffness is not enough and it is easy to break; so the whole horizontal bearing capacity is less than that of C₁ but better than that of C₂.

Abstract:Some glutinous rice pulp, waste glass slag and rubber are added into plain soil to form modified soil material for the rational use of waste materials to improve the mechanical properties of raw soil material. According to the five kinds of mix proportion scheme, the size in diameter 102mm with high 116mm cylinder specimens were prepared. Through the axial compressive strength test, the experimental phenomena, compressive strength, deformability, load-displacement curves of specimens with different proportions are compared, and the mechanisms of different admixtures are analyzed, and the influence laws of compressive strength with different admixtures and different amount are studied. The reasonable range of he mixing amount of glass slag and rubber is proposed. The results show that the compressive strength of the soil can be enhanced by the incorporation of glutinous rice pulp into the soil. With the incorporation of glutinous rice pulp, glass slag and rubber, the compressive strength and deformation capacity can be improved, but the compressive strength decreases after 3.12MPa with the increase of the amount of glass slag and rubber.

Abstract:The displacements of soil around pile and pile core soil under harmonic SH waves are obtained based on one-dimensional wave motion model. Under the three-dimensional axial symmetry case, the vibrations of soil around pile and pile core soil caused by horizontal harmonic concentrated load and SH waves are solved by potential functions and variable separation method, and the radial and ring displacements of soil around pile and pile core soil are also obtained. The vibration of pipe pile under harmonic concentrated load and SH waves is investigated by considering pipe pile-soil dynamic interaction and continuous conditions. And the dynamic magnification factor at pipe pile has got. The results of numeral example indicate that pipe pile has resonance phenomenon under harmonic SH waves, the pipe pilecould lead to instability if the pipe pile wall too thin, and seismic performance of pipe pile is better than solid core pile under the same outside diameter.

Abstract:The cross-section mechanical properties of full-size detachable formwork with steel bar trusses were tested under construction stage and the failure mode as well as the mechanical behavior were analyzed under monotonic load, and the cross-section properties were calculated using load-deflection curve method and ultimate moment method. The analysis results showed that truss model with its chords to be continuous and webs can be used during construction, the error was much large between results of load-deflection curve method and theoretical values, and the reason was that the specimen in failed procress is controlled by deformation, rather than the strength; and the additional deflection was generated by the relative slip between connector and reinforcement; and ultimate moment method were in good agreement with theoretical values. On the base of results, the suggestions were given that the biggest unsupported length under simply supported or continuous beam model.

Abstract:Considering the shear deformation effect of piles, the calculating theory of m method assumption for piles was presented by using the single generalized displacement theory of deep beam. The initial parameter formulae to horizontal displacement, slope, moment and shear force were derived. The unified non-dimensional functions were also put forward. According to the boundary conditions, the initial parameters solutions were determined. The changing figures of non-dimensional functions with converting length and ratio of bend stiffness to shear stiffness were plotted. Some conclusions were summarized that when the converting length was less than 3.0, there was little influence of the ratio of bending stiffness to shear stiffness on the non-dimensional functions, while the converting length was greater than 3.0, the influence of the ratio of bending stiffness to shear stiffness on the non-dimensional functions became obvious; the influencing degree of the shear deformation effect was related to the boundary conditions. Example results showed that shear deformation can enlarge the horizontal displacement at the top, lift the position of zero moment, change moment distribution and magnify the soil pressure on pile.

Abstract:Finite pole element method is presented for P-Δ effect analysis of pile and bearing while shear deformation is well considered. It is assumed that horizontal displacement of the pole element has a longitudinally cubic power function and the shear displacement has a longitudinally linear function, the P-Δ effect pole element rigid equation considering the shear deformation produced by lateral load and the radial component of vertical load, is derived. The P-Δ effect pole element rigid equation considering the shear deformation only produced by lateral load is derived in the paper. The P-Δ effect pole element rigid equation considering the shear deformation only produced by the radial component of vertical load, is derived in the paper. And the P-Δ effect pole element considering the shear deformation only produced by lateral load can simulate the bearing working eccentrically well in real-time. Matlab process of finite pole element method for P-Δ effect analysis of pile and bearing is edited, and case analysis is done, and the theory and the method is proved good. Finally conclusions are drawn as follows:(i) the P-Δ effect analysis result of pile will increase obviously while the eccentric bending moment of the bearing is well considered; (ii) the deformation has little effect on the P-Δ effect analysis result of the pile and bearing.

Abstract:Multiplanar KK-type tube-gusset plate connections are the main joint types in transmission steel tubular tower, the safety of the joints are critical to the entire tower. Compared to K-joints, the mechanic characteristics of KK-joints are more complex after considering the multiplanar effects in the actual structure. Based on the bearing capacity test of K-type tube-gusset plate connections, parameterization analysis on the two kinds KK-type tube-gusset plate connections are conducted respectively, the geometric parameters and the axial force of the main tube together with other factors on the influence of the ultimate bearing capacity of multiplanar KK-joints are studied in detail. According to the results of large scale finite element parametric analysis, and considering the influence of various factors on the ultimate strength of the joints, calculation formulas of KK-type tube-gusset plate connections ultimate bearing capacity are proposed.

Abstract:At present, the arch deformation is considered mainly when the engineers determinate the construction procedure for the cast-in-place RC arch with arch centering, but the arch stress is often ignored. Gan Hegou Bridge in Guizhou province is select as the case study. The positions of dividing rings sections are defined preliminarily according to original construction scheme. The simulation analysis considering the whole construction process is done by the use of MIDAS software. After the arch deformation and arch stress of various schemes are calculated and compared, reasonable construction procedure is obtained. The pouring sequence of the first arch ring is the first springer, the second vault and the last middle section. The pouring sequence of the second arch ring is the first vault, the second springer and the last middle section. The springer、vault and middle section of the third arch ring are divided into the two sections. The pouring sequence of the third arch ring are the first section of the vault、springer and middle section, then the section of the vault、springer and middle section. The pouring sequence of spandrel construction is the first vault, the second springer. The measured values of the arch deformation and stress are agreement with the calculated values. The results show the procedure and method are reasonable and reliable.

Abstract:The optimization of the sectional dimensions is studied to make the ratio between performance and steel amount of steel sections become optimal. However, the optimization analysis of lip angle involving the eccentric compression is lack. A technique with the genetic algorithm and formulae for predicting the distortional critical stresses of cold-formed lipped channels subjected to eccentric compression is developed to optimize the angles of lips of channels. The cold-formed lipped channel columns under eccentric compressing have been taken as examples. The genetic algorithm regards the angle of lip and eccentric distance as design parameters. This method not only can decrease workload and aimless calculation but also can obtain accurate optimal angles. The distortional critical stresses of cold-formed lipped channels with different dimensions under simply and clamped supports are obtained, based on the finite strip analyses. The optimal angles of cold-formed channel steel members with different eccentric distances are presented. For designer's convenience of design and application, the degree of 100 is suggested.

Abstract:PBH test model is designed and 240000 times fatigue tests were conducted to investigate the steel box-concrete composite structure of PBH shear connector under repeated load fatigue performance. The fatigue failure pattern and test data are analysed. Take advantage of the finite element software to analysis the floor opening aperture, wear into the steel bar diameter, concrete strength influence of the PBH fatigue. Results showed that the PBH's fatigue failure pattern is similar to static, which is concrete surface appear oblique splitting cracks, concrete tenor crushed, through the steel yield. Fatigue damage can be divided into beginning and development and damage three stages, the development stage accounted for 91.7% of the whole fatigue stage, structural stiffness in the beginning and development stages degradation slower, fast during the damage stage. Three parameters are of great influence on the fatigue life of PBH, among them through the bar diameter's influence particularly prominent.

Abstract:Four analytical models are proposed for examining the effect of gravity abutment-backfill interaction based on current seismic design codes from home and abroad. The mechanical constitutive relationships as well as computing formulas are presented. Nonlinear time history method is applied to comparatively study the effect of abutment-backfill interaction on a rigid frame continuous bridge with double thin-walled piers, which is currently under construction. The results showed that only the spring model can obtain the closest higher-order elastic modes to those of the refined model. In the longitudinal direction, the results from the roller model and the bearing model are both much smaller than that of the refined model. The error of the spring model, compared with the refined model, is the smallest with the critical internal force errors not exceeding 20%. In the transverse direction, the bearing model is the closest to the refined model in calculating the internal forces, and both the spring model and the roller model predict conservative results with respect to that of the refined model. The influences of the abutment stiffness and effective participating mass on the critical seismic internal forces are smaller than 10% and 15%, respectively. Hence by comprehensively taking the prediction accuracy and computational cost into consideration, the spring model is the most suitable choice in seismic design of bridges.

Abstract:In the background of the rapid growth of urban space, it is helpful to carry out the study of urban spatial growth performance to solve the problem of urban spatial growth. This study provided basis of determining the development strategy of urban space and formulating spatial policy. Evaluation methodology of urban spatial growth effect is the way to judging the element configuration and the operation of elements is reasonable, efficient and fair during the process of urban growth space. Three evaluation systems are established in this paper, there are structure effect, economic effect and fair allocation effect. Evaluation of urban spatial growth effects by objective law will get space growth effect evaluation function. An empirical analysis of Chongqing city as an example we can get these results:the urban spatial growth effect of Chongqing from 2004 to 2013 is on the rise, structure and fairness is also on the rise; the reasonable allocation effect and the economic allocation effect are significant. These results reflect the urban construction land use structure optimization, land use efficiency and other aspects of the problem.

Abstract:Generally, the cost of tornado-resistant design of structures is much higher than expected loss of wind-induced disaster. Therefore, load codes for the design of building structures generally take no consideration of tornado. However, some important engineering facilities with extreme high security requirements, like nuclear power plants, need to consider possible tornado-induced wind loads. This paper starts with the state-of-art of tornado models, then, the determination of direct wind pressure on structures, indirect action of tornado-generated missiles and the tornado-resistant design of special engineering structure like nuclear power plant, are summarized. Then it points out the necessity of calculating the tornado-induced wind loads by considering axial wind suction, translational motion of wind field and torsional response. The effect of the relative stiffness and end form of projectiles should be taken into account in the impact load of tornado-generated missiles.

Abstract:The influence factors, adsorption isotherm and kinetics of phosphate removal by modified steel slag were investigated in this study. In addition, the modified steel slag was applied to the phosphate removal of effluent after biological treatment. Result showed that the concentration of total phosphorus decreased to 0.678 mg/L and the removal rate reached 93% after adsorption by modified steel slag at 10 mg/L of initial phosphorus concentration, 10 g/L dosage of modified steel slag and pH 7;The adsorption of phosphorus by modified steel slag was in accordance with the Langmuir isotherm model and the theoretical saturated capacity was 1.98 mg/g. The adsorption process could be well described by the pseudo second-order kinetics(R₂>0.99). Furthermore, in the treatment of domestic wastewater, the total phosphorus concentrations of effluent reached the first B grade discharge standard of GB18918-2002 after treated by modified steel slag for 2 hours with a dosage of 50 g/L.

Abstract:The micro-organisms of plant roots, wetland filler and wetland soil of subsurface flow wetland consumptive municipal sewage treatment plant effluents bypass test systems, in Changzhou City, north of the city sewage treatment plant, were studied through microscopic examination, urease, phospholipid fatty acid (PLFA) and other analytical tools for related seudies to reveal the characteristics and mechanism of micro-organisms with Subsurface Flow Wetland consumptive municipal sewage treatment plant effluents. The results showed that plant roots, filler contained rotifers, amoeba and other protozoa and Volvox, Volvox used the N, P and other pollutant of tail waters through photosynthesis biological metabolism, removal of N、P, etc, under conditions of low-carbon. The average content of wetland urease(N) was about 22.43 mg/g, the activity of urease was linearly related to the removal of TN, the higher the activity, the higher the removal rate of TN. Saturated fatty acid (PLFA) content was 99.30%, unsaturated fatty acid content was only 0.70% in Wetland fillers, which with subsurface flow wetland treatment PLFA contents of municipal sewage is very different (76.97% and 23.03%, respectively). The amount of fatty acid biomarker as an indicator, reveal wetlands matrix formed with aerobic bacteria was dominant structure of microbial ecology. Volvox, aerobic microorganisms was the main carriers of microbial removal of TN and other pollutants in low carbon source tail water.

Abstract:Design of district metered areas(DMAs) in water distribution system was performed based on complex network spectral clustering and graph theory. First the number of DMAs was determined, and graph weighted adjacency matrix and Laplacian matrix were established. Then k-way spectral clustering algorithm was used to discover the optimal clusters hidden behind eigenvectors of Laplacian matrix, leading to the best layout of DMAs using genetic algorithm and K-means. PageRank and shortest path algorithm were adopted to ascertain the location of meters in DMAs and valves between DMAs to achieve the optimal design of DMAs eventually. And a real water distribution system was tested and the results showed that the proposed method was effective in DMAs design.

Abstract:Oxidative degradation of CBZ in aqueous solution was carried out by coupling electrolysis with persulfate. Experiments were carried out under a batch-wise mode to evaluate the influence of various operation parameters on the electrolytic behavior, such as initial acidity of aqueous solution, temperature, voltage, persulfate anion concentration. After one hundred minutes reaction, the degradation rate of CBZ was 25.5%、59.3%、78.1,and the TOC removal rate was 8.25%、23.48%、26.68%, which was carried out by sole persulfate, electrolysis and coupling electrolysis with persulfate, respectively. The degradation efficiency of CBZ was effectively enhanced as temperature increased. The degradation rate of CBZ were 60.2%, 78.1%, 90.1% within one hundred minutes at 288 K, 298 K, 308 K, respectively. The degradation rate of CBZ was increased with concentration of persulfate. When the concentration of sodium persulfate reached 40 grams per liter, CBZ degradation rate was 94.7% within one hundred minutes. The degradation efficiency of CBZ as follows:pH3.0 >pH5.0 >pH7.0 and 6 V >5 V >4 V.