Advances in Civil Engineering II

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Authors: Tao Hong, Mei Jun Lu, Chu Wei Zhou, Jian Zhang
Abstract: Analysis of Mindlin plate is completed. And combined with gradient optimizing method, the Gaussian Markov identification analysis of the soil parameter for the foundation is studied and put forward in detail. After the mechanical theory for the plate on the foundation is introduced, the controlling differential equations of the plate on the foundation which is subjected to vertical loads are deduced. And linear algebra controlling equations for the plate are achieved which leads to solve the original differential equations more easily when the corresponding solutions to the plate on the foundation are gained with Fourier transformative theory. The Gaussian Markov error function for the soil parameter on the plate is established and applied with the gradient optimizing method. The identification steps on the Gaussian Markov error function for the soil parameter are listed. The calculation results verify the conclusions that the soil parameter of the foundation can be efficiently inversed by applying the Gaussian Markov theory. When different initial soil parameter is set, the iterative computations can be convergent to the true value of the soil parameter. And this Gaussian Markov method can also be applied for the problem of inversed analysis of parameters for other foundation models.
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Authors: Yan Liu
Abstract: A constitutive model for unsaturated soils is developed. Based on the SFG approach, the deduced LC curve has a smooth transition from saturated state to unsaturated state. The yield stress does not increase with increasing suction monotonically, and thus could reproduce plastic volume change of a slurry soil caused by drying. The model takes account of the effect of saturation, lead to different yield surface for wetting and drying. Soils with same suction but different saturation can have different yield stress. The model is used to simulate exited test data and the predicted curves agree well with the data points.
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Authors: Shi Bo Li, Hong Jian Lu
Abstract: Weibull distribution was applied to calculate the ground subsidence and deflection value, in order to analysis accurately the influence of ground subsidence caused by underground mining on high voltage electric power lines. The results showed that the effect of reducing surface subsidence was notable and the high power line was working normally. It was accurate enough to calculate ground deformation by using Weibull distribution, and Matlab program can be used to solve the function feasibly.
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Authors: Jian Bin Xie, Jing Fan, Zhi Liang Wang, Wen Lian Liu, Jing You Hu
Abstract: Based on the engineering geological, hydrogeological conditions and survey results of Zhelamuqing tailings dam, two types seepage problems in the tailings dam which are saturated seepage and saturated - unsaturated seepage were described and solved by Darcy law and Richards Equation respectively. Then the three-dimensional seepage field of tailings dam under steady saturated state was simulated by finite element method (FEM). And the seepage line of saturated - unsaturated seepage field in the tailings dam was simulated and predicted by numerical analysis method when the embankment is enduring the flood. Subsequently, the simulated seepage line of saturated - unsaturated seepage field in the tailings dam was verified by the survey result. Results show that it is feasible to describe the saturated seepage and saturated - unsaturated seepage by means of Darcy law and Richards Equation respectively and it is effective to simulate the three-dimensional seepage field of tailings dam under steady saturated state by using the finite element software Midas GTS. Results also show that the simulated seepage line of saturated - unsaturated seepage field in the tailings dam agree with the survey result.
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Authors: Yong Gang Cheng
Abstract: Anchoring technology is an engineering research focus for its successful application in practice and huge economic benefits in slope stabilizing. To construct an anchorage, all steps are in the same importance and any mistake may cause an entire failure. In order to promote the combination of the applications and the theoretical studies of slope anchoring, the theoretical results, practical utilities and quality-control methods on slope anchoring in recent 20 years were discussed in this paper. The load transfer mechanism of anchorage body and the active mechanism of ground anchorages were detailed mentioned. As to practical utilities, the construction standardization, anchorage type, grouting, corrosion prevention, and other techniques were presented. When it comes to quality controlling, some discussions on anchorage field experiments, long-term monitoring, and non-destructive examination were carried out. Finally, some suggestions are proposed on open questions about theoretical study, practical utility, quality controlling.
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Authors: Shu Lian Wen, Hai Bin La, Chang Zhong Wang
Abstract: Slope stability is affected by many factors, their effects on the slope stability may be big or small. Along with continuous improvement of the various calculation methods, it is more important to identify the main influencing ratio factors in the process of analyzing the slope stability than to select the method of calculation .Therefore the paper analyzed the main internal factors, calculated to get five curves that showed the relationship between these influence factors and the safety factor, The results show that unit weight of soil, cohesion and internal friction angle are the main factors affecting slope stability. Then, it can take corresponding measures in the process of targeting and optimal designing slopes in order to achieve security, economic and efficient goals.
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Authors: Jiang Wei Xue, Jing Luo Cai, Yong Yang, Xin Sheng Ge
Abstract: To classify building founation into shallow foundation and deep foundation is not always right, may lead to erroneous judgement or discrimination, and it is difficult to define the pile partner (Variable Rigidity Pile), so the concepts of direct and indirect footing (foundation) are to be presented for the first time, which seems to be more reasonable and scientific, pile partner can be directly foundation, and can also be indirect foundation, mainly distinguish according to the distance or modulus between pile top and pile cap. If the pile top and pile cap keep at a distance, then it is direct foundation (footing); If the pile top connect to pile cap, connection types can be "rigid joint", "hinged joint", or contact with each other, it is indirect foundation (footing).
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Authors: Jing Wang, Xiao Long Qu, Chun Li Wu, Yi Ming Xiang
Abstract: Three different plasticity index subgrade soils are selected from seasonal frozen soil area. Triaxial compression test under different confining pressures are executed on the samples exposed to 0 to 7 times closed-system freeze-thaw cycles. The conclusion gotten is that to the same kind of soil under the same freeze-thaw cycles, the shear strength increases with confining pressure; Shear strength with the same confining pressure decreases with the number of freeze-thaw cycles; With the same confining pressure and the same freeze-thaw cycles, shear strength increases with the plasticity index. Exponential function is adopted for multiple nonlinear fitting on the test results. The relationship between shear strength and confining pressure, plasticity index, freeze-thaw cycles is obtained and shows a good correlation.
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Authors: Jing Yang Ding, Jia Dun Liu, Chao Li, Hai Yang Yi
Abstract: Sample of layered rock salt was subjected to three-point bending test with SHIMADZU SEM (Scanning Electron Microscope) system monitoring. Initiation and propagation of crack in both salt rock and mudstone impurity were recorded, so was the micro-structure in the interface between rock salt and mudstone impurity. By analyzing the SEM photos of failed sample, it is found that crack initially comes out in salt rock or mudstone impurity rather than the interface. Three-point bending test was numerically calculated based on bridging model. Calculation results show that the interface is not weak plane, and that the failure mode of salt rock and mudstone impurity is closely correlated with the dip angle of the infinitesimal element of the interface. When the dip is larger than 70°, tensile failure firstly occurs in mudstone impurity. When the dip is smaller than 70° , tensile failure initiates in salt rock.
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