Abstract:

Abstract:Based on the assumptions of exponential fluid and narrow plate model, formulas for calculating the climb height of grout in shaft base post grouting was deduced. It is shown that the climb height of grout is mainly related to the grouting pressure, the shaft length, the shaft diameter and the mudcake thickness. With the theoretic analysis and case study, it is indicated that thicker mudcake, higher grouting pressure and shorter shaft length would lead to larger climb height and larger risk of overflow. The overflow of grout would be prevented by reducing the grouting pressure, the mudcake thickness and debris thickness. The overflow of grout can also be prevented by increasing the strength of mudcake. For the overflow shafts, intermission grouting would be employed. Compared with the ordinary shafts, the former has higher bearing capacity than the latter, resulting from the grout upwards along the shaft soil interface.

Abstract:In order to reduce the differential settlement of gravel pile foundation under large scale oil tank, axisymmetric numerical simulation method and finite element method was employed to study the pile length, the exchange rate of length, the length of the cushion course to the influence of differential settlement and the relationship of negative lateral displacement and the settlement. It is found that: differential settlement has a minimum range of pile length. For the oil tank foundation center, by keeping the pile diameter, increasing pile spacing can increase the rate of exchange and obtain smaller differential settlement in relatively smaller displacement rate conditions. And by keeping replacement rate unchanged, the larger the pile diameter(namely the looser pile spacing) is, the smaller the differences settlement of the gravel pile foundation is. Moreover, pile length adjustment and the exchange rate have obvious effects on different subsidence and not obvious effects on the length of the cushion course. The appearance of oil tank foundation negative lateral displacement is one of the most important features of differential settlement adjustment.

Abstract:Bearing capacity of foundation is conventionally calculated based on the linear Mohr–Coulomb failure criterion. However, a amount of experimental data shows that the strength envelops of almost all types of rocks are nonlinear over the wide range of normal stresses. The strength envelope of rock masses is considered to follow a modified Hoek Brown nonlinear failure criterion. Therefore, according to the upper bound approach, based on Hoek Brown nonlinear failure criterion and a multi tangential technique method, the relevant programs were developed by means of the software Matlab and the sequential quadratic programming optimization theory. And the calculation and the analysis of affecting factors bearing capacity for rock foundation were employed. It is found that the major factors affecting bearing capacity of rock foundation are GSI and mi, but the weight of foundation ,overload and the disturbance coefficient of excavation D have a considerable influence on bearing capacity of rock foundation when the value of GSI is small . Compared with the generalized tangential and the finite element or finite difference numerical techniques, the single tangential technique method would bring relatively great risk, because the calculation results are larger than those of the actual bearing capacity of foundation.

Abstract:The Quasi static tests of one steel frame and two the composite deep beams infilled steel frames were carried out. The effects of the deep beams on the load capacity, ductility, hysteretic property and energy dissipation of pure steel structure were analyzed. It is found that the hysteresis curve is a straight line with the constant of the stiffness at the beginning and without residual deformation. And the hysteresis curve of specimen was full after yielding, and the skeleton curves had a clear plastic flow phase with triple linear. The lateral drifts of the beam specimens at failure were 1/25 and 1/22. The composite deep beams enhance the initial stiffness, yield load and maximum load bearing capacity of steel frame. Therefore, seismic performance of the composite deep beams is better.

Abstract:At present, euqi distance circle model is generally used for directly fitting acceleration peak attenuation. Epicenter distance or focal distance is the only coordinate statistical parameter of seismic station. For large earthquake with a long fault, the iso seismical curve of euqi distance exists serious deviation from realistic iso seismal curve. Six area model was addressed to correct the deviation. With the model, seismic station was divided into six areas by two cut lines of coincided with fault and four cut lines perpendicular to fault. The acceleration peak attenuation curve along cut lines was fitted to analyse the relationship between attenuation curve and area seismic station. Take Wenchuan earthquake for an instance, the accuracy of the model is much higher than that of euqi distance circle model and a little higher than that of four area elliptical model. And the model is more accurate than four area elliptical model in reflecting hanging and foot wall effect and direction effect.

Abstract:The mountain hazards like snow avalanches, landslides, rock falls, debris flows and so on all have strong power of destruction which seriously threaten human’s lives and belongings. Therefore, it is necessary to study more the development of these disasters in order to prevent them. Setting up obstacles is the primary measure to control the movement and deposition process of mountain hazards. For the study of the influence of this measure on the development of disasters, the numerical simulation calculation aiming at the flow and deposition process of the granulars flowing past different built obstacles was made by the theory of SH granular flow and the method of finite volume discretization based on Roe's Scheme. Futhermore, the influence of different settings of obstacles on the granular flow is discussed. The numerical results show that the settings of obstacles have a great effect on the process of granular flow. That is, the effective precaution against the disasters is no other than setting up the obstacles correctly. As the numerical simulation calculation can optimize the setting of obstacle, it provides a reasonable and economic reference scheme of disaster prevention and planning of mountain area.

Abstract:Aiming at the influence of mastics to aggregate adhesion on the performances of asphalt mixtures, three modeling techniques were adopted to prepare composite asphalt mixtures specimens. The influences of silane coupling agent on their road performances were studied and coupling mechanism was analyzed with Infrared Spectroscopy (IR) and Scanning Electron Microscope (SEM). The results indicated that the road performances at 7 day and 28 day curing age increased in the beginning and then decreased with the increase of silane coupling agent dosages. The road performances, such as freeze thaw splitting strength ratio, Marshall stability and compression modulus would be enhanced 10%~30% at 0.6% in asphalt emulsion mass. There was Si O Si chemical bond on interface between mastics and modified granite aggregate by Si O chemical bond of silane coupling agent. Surface of cement asphalt emulsion mastics was rough and its structure was dense. The cement asphalt emulsion mastics can be adhered to granite aggregate surface and mastics to aggregate interface structure is improved with silane coupling agent addition.

Abstract:To improve the performance of asphalt rubber mixture under high temperature, an optimal proposal was put forward which selected asphalt rubber mortar and aggregate gradation as the main objects. According to experimental tests, the anti rutting factors and phase angles of asphalt mortar was studied with different rations of filler bitumen. And then, with the characteristics of asphalt rubber, the optimal gradation was presented by means of the adjustment of aggregate gradation which chose dynamic stability and relative deformation as value indexes. The results shew that asphalt rubber mixtures would show an optimal high temperature performance if the following measures can be taken: (1) making an adjustment of ratio of filler bitumen to about 1.2; (2) replacing mineral powder with cement; (3) making an adjustment of aggregate gradation and lower the proportion of mineral powder based on SMA.

Abstract:Based on 4 span continuous straight bridges, the demands of inelastic displacement and elastic displacement of the bridge structures under earthquakes were obtained from inelastic time history analysis and elastic response spectrum analysis, respectively. Then the ratio of the inelastic displacement demand to its corresponding elastic displacement demand was investigated with parameter statistical method. It is found that the inelastic displacement demand approximates its corresponding elastic displacement demand for the bridge structures with long vibration periods. And because the elastic displacement demand can be calculated by relatively simple elastic analysis method (such as elastic response spectrum analysis), it can approximately replace the bridge structure’s inelastic displacement demand under earthquake to simplify its displacement based seismic design.

Abstract:The merits of the sewage source heat pump system are remarkable on energy efficiency and pollution reduction. Based on the fouling resistance law, the test bench was established on growth characteristics of fouling in copper pipe. The experiment has been carried on and the growth characteristics of fouling in copper pipe were obtained with the asymptotic agglomeration forecast model. It is found that the fouling induction period of the sewage is 21 hours in the smooth copper pipe, the fouling resistance settling time is 95 hours, and the stable fouling resistance is for 1.5×10-5m2K/W.

Abstract: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.

Abstract:The effects of initial pH of direct dark brown MM dye solution, H2O2 concentration and dosage of Fe Ni Mn/Al2O3 on the degradation ratio of direct dark brown MM were studied by using low frequency ultrasound. By the Box Behnken centre united experiment design and response surface methodology, a predictive polynomial quadratic model was set up and the optimum extraction conditions were developed. The optimization is that pH of dye wastewater is 3.79, dosage of H2O2 is 1.74 mM, dosage of Fe Ni Mn/Al2O3 is 1.65 g on the initial dye concentration 100 mg/L. 91.09 % of direct dark brown MM was degraded under the optimal conditions. The experimental results are in good agreement with the predicted values of the model equation with 1.35 % deviation.

Abstract:The characteristics of granules of heterotrophic and autotrophic bacteria were studied. The autotrophic granules were characterized by smaller granule size, higher density, higher concentration of extracellular polymeric substances (EPS) and weaker strength compared with the heterotrophic ones. The diameter and density of autotrophic granules were changed in the same fashion, resulting in stable granules, and the heterotrophic granule, however, grew up with the increase of diameter and the decrease of density. According to the strength analysis, it is proposed that in the autotrophic system, the balance between EPS and porosity is the main reason for the long term stability. However, the balance could not be obtained in the heterotrophic system and that the operational conditions could not control the overgrowth of filamentous bacteria was the reason for the instability.

Abstract:A strain that have capable of metabolizing phenol as a sole source of carbon and energy sources was isolated from an sludge collected from textile chemical plant in Taiwan. It was identified as Pseudomonas sp. based on its morphology, physiological, biochemical characteristics with an automatic biometrical system and the 16S rDNA sequence analysis. It is shown that the biodegradation of phenol was optimized at culture medium pH 8.5 and 30℃.Under the condition, the strain degraded phenol completely within 17h even though the initial phenol level was high to 500 mg/L. With the study of dynamic growth kinetics of suspended cells, the value of μmax, KS and KI were found to be 0.452 h-1, 28.617 mg/L, 782.4 mg/L for strain CN 6 degrading phenol using Haldane's inhibition kinetic models.

Abstract:The rules of migration and distribution regulation of tubifex in filtration were studied in the pilot system. Meanwhile, the influences of filtration rate, filtration cycle and backwashing on the worm’s migration and distribution in filtraion were discussed. The results showed that both the worm’s length and the particle size of filter media had obvious effects on migration and distribution: the smaller the worm’s length and the larger the particle size of filter media were, the stronger the worm’s migration capacity was. The filtration rate was the main migration power of tubifex in filtration, which meant high filtration rate could result in the worm’s leakage risk. Prolonging filtration cycle promoted migration, thus it is beneficial to control tubifex leakage risk that shortening filtration cycle. The remove of tubifex in a real sense can be realized by backwashing. And the stronger the backwashing intensity is, the better the removal efficiency is. Based on the experimental results, to control the worm’s leakage risk effectively, filtration rate and cycle would be lower than 9.4 m/h and 12 h, respectively. Backwashing intensity would be controlled about 25 L/s·m2, at which the obtained tubifex removal efficiency was 97.7%.

Abstract:A novel hydrolysis acidification reactor in concentric structure was designed and developed, which could improve the biodegradability of wastewater effectively by the enhancement of the mixture performance due to the stirring and reflux. The pilot scale study showed that the COD removal rate could reach over 46% and 36% respectively treating the two different kinds of refractory wastewater. Moreover, the reactor could cut down the operational cost through the variation of the operation mode. According to the comparison with other hydrolysis acidification reactors, the result showed that a 6 percentage point of improvement in COD removal could be reached to the novel hydrolysis acidification reactor.

Abstract:Series of Ti based electrodes of Ti/PbO2, Ti/SnO2 Sb2O3/PbO2, Ti/SnO2 Sb2O3/PbO2 Cu, Ti/SnO2 Sb2O3/PbO2 Ni and Ti/SnO2 Sb2O3/PbO2 Fe were prepared by thermal decomposition method. And with these electrodes as anodes and the acid fuchsin as simulated dye wastewater, the electro catalytic oxidations of the simulated dye wastewater were performed. With the comparison of effects and reaction rate of different electrodes and the analysis of acid fuchsin oxidation process, it is shown that the electro catalytic abilities of the Fe modified electrode Ti/SnO2 Sb2O3/PbO2 Fe and Ni modified electrode Ti/SnO2 Sb2O3/PbO2 Ni have higher removal efficiency and removal ratio while the Cu modified electrode Ti/SnO2 Sb2O3/PbO2 Cu did not present a obvious modified effect compared with those by Ti/PbO2 and Ti/SnO2 Sb2O3/PbO2. Based on the test data, first order kinetic models of these five electrodes were established. From the UV VIS spectra of the Ti/SnO2 Sb2O3/PbO2 Fe electrode generated under the condition of 100 mg/L of initial concentration of acid fuchsin, 75 mA/cm2 of the density and 12 g/L of the electrolyte concentration (Na2SO4), it is found that the characteristic absorption peak of acid fuchsin at λmax =545 nm nearly disappeared in 60 min and the acid fuchsin was removed. However, some small molecular intermediate products were generated in the electro catalytic oxidation.

Abstract:Spill of volatile poisons into natural water bodies causes water pollution and then air pollution arises from water pollution because of volatilization. In order to explain the coupling of water pollution and air pollution, the dimensionless Henry constant of volatile poisons was used to establish coupling diffusion model based on compressed VOF method and the double film theory explained for volatilization. A high resolution bounded differencing scheme for arbitrarily unstructured meshes was applied to simulate coupling diffusion of trichloroethylene and tribromoethylene. The simulation results are in good agreement with those from single phase model. The influence of environmental temperature, wind velocity and the dimensionless Henry constant on the mass transfer across gas liquid interface was analysed.

Abstract:In the conditions of low temperature and low pressure, the white hydrated calcium silicate powder was produced through the dynamic hydrothermal synthesis technology. Through studying the properties of hydrated calcium silicate powder which is made by different synthesis temperature and the influence of hydrated calcium silicate powder,calcium carbonate and quartz powder on the mechanical properties of silicone rubber, it is found that the hydrated calcium silicate powder which is produced at （120±5）℃ has better performance enhancement. Besides the size of particle, the surface reactivity is also an important factor.

Abstract:Recently, most impermeability seudies of polypropylene fiber concrete, as a new sort of tunnel lining waterproof material,are limited to the impervious mechanism and unable to be satisfied with the engineering need. On the basis of fracture mechanics and the micro structure mechanics, the resistance of fiber to the crack extension inside concrete and it’s SIF were deduced, the analytical formula of fiber resistance effect to the opening mode crack extension was presented as well. Meanwhile, the impervious performance of polypropylene fiber concrete was explained reasonably by the numerical calculation of the resistance effect. On the other hand, for comparing the impervious performance of polypropylene fiber concrete with that of UEA concrete, the impervious performance experiments of four groups of different types of concrete were carried out, it is presented that the former is superior to the latter. More than that, adding double polypropylene fiber and UEA to the concrete with proper proportion will make the impervious performance much better.

Abstract:By means of SEM, XRD and calorimeter C 80Ⅱ, the hydration characteristics and hydration kinetics of cement based materials with and without P2O5 incorporated were investigated. It is found that the amount and size of hydration products incorporated with P2O5 were decreased dramatically. When 3.5% P2O5 was added in cement, total amount of hydration heat was decreased by 32.6% and initial and final setting were delayed by 1.10 h and 12.54 h respectively. In terms of mechanism analysis, P2O5 had little impact on cement hydration mechanism, and accelerating stage was controlled by chemical reaction, decreasing stage controlled by both chemical and diffusion reaction while stabilizing stage controlled by diffusion alone. The hydration resistance in both accelerating and decreasing stage was elevated while decreased in stabilizing stage. The activation energy in both accelerating and decreasing stage were reduced and increased in stabilizing stage. P2O5 was favorable to hydration of C3A yet retarded hydration of C3S and C2S.

Abstract:This investigation focuses on influence of ultra low temperature on frost resistance of cementitious material by freeze thaw cycles test in which liquid nitrogen was applied as ambient medium. The appearance, mass and strength change before freeze thaw recycle and after were measured, respectively. Micro structure of cementitious material before and after freeze thaw recycle was tested by using scan electron microscope (SEM). It is found that, under the condition of ultra low temperature, frost resistance of concrete is better than that of mortar. And the frost resistance of concrete increased with the improvement of concrete strength. The SEM results reveal the structure defect is produced clearly when specimen freeze in liquid nitrogen and thawed in water. It is concluded that freeze thaw recycle with ultra Low temperature is an effective quick method to evaluate the frost resistance of cementitious material because destroying progress was accelerated and experimental time was redned.

Abstract:In allusion to the cable tension controlling problem in the parallel strand stayed cable construction, on the basis of construction techniques of applying tension loads one by one, the mechanical model of the cable girder tower in the process of construction was established. With the equal cable tension as a goal, the formula was deduced with the method of forward analysis, which could be used to calculate the initial tension of each strand in construction. The effect of temperature variations on the initial tension could be eliminated by using the formula with the method of equivalent tension. Moreover, a method was proposed to measure the cable tension in the processes of construction and performing the function. Finally, the practice in one cable stayed bridge in the north indicated that 1) the uniform cable tension could be obtained by the proposed method; 2) the tension error range of whether a single strand or the whole stayed cable was within 5%, and the result could meet the needs in construction control; 3) the method could provide reference for the similar stayed cable construction.

Abstract:Combined with construction of north anchorage caisson, field pumping tests were carried out. Permeability coefficient was acquired for dewater sinking. Water yield of single well and total water inflow of caisson excavation were calculated. It is found that the measured amount of total water inflow is slightly larger than the theoretical value. Based on effective stress principle, the compression of phreatic water aquifer caused by dewater is almost negligible，and the ground settlement is mainly composed of confined water aquifer compression. The calculated settlement curve along the levee was in good agreement with the measured data.

Abstract:Mechanical behavior of Suspen domes during construction is different with that in service and even more adverse because of cables introduced in the structures. By studying the actual suspen dome projects, the key construction parameters for them were extracted and tensioning mechanism of hoop cables was studied. Then according to the tensioning mechanism and the key construction parameters, a numerical model and an algorithm for the whole process of tensioning were proposed. Moreover, a case study was addressed to approve the effectiveness.