Advanced Materials Research Vols. 243-249

Abstract: It is extremely important to establish hazard maps showing earthquake-induced displacements, safety factors and probabilities of failure. The combination of pseudo-static method and displacement-based method is commonly used to evaluate the stability of gangue slope. Conventional calculations are formulated in terms of a linear Mohr–Coulomb (MC) failure criterion. However, experimental data shows that the strength envelops of almost all types of rocks are nonlinear over the wide range of normal stresses. In this paper, the nonlinear failure criterion is introduced. The resulting safety factor and permanent displacement are discussed and demonstrated using several real earthquake records.

Abstract: On the basis of establishing mechanics model, viscoplasticity theory and principle of minimum potential energy , temporal correlation of the filling body was analyze . The necessary conditions of the filling body’s stability and the formula of minimum steady time were obtained. Theory analysis shows that the filling body’s steady time decreases with the increase of plastic area; when elastic modulus, hardening parameter and coefficient of viscosity are exogenously decided. The filling body’s steady time decreases with the increase of elastic modulus, and increases with the coefficient of viscosity. Gradual failure theory indicates that plastic range of filling body has a close relationship with in-situ rock stress, it provides theoretical basis for parameter selection and design of the gob-side entry retaining.

Abstract: Intense earthquake shaking inevitably ruptures the rockmass along the fissures and bursts mountainous slopes, and these understable slopes are namely cracked slopes. For such slopes, aftershocks, rainwater infiltration and others factors will inevitably induce crack propagation and the crack thus gradually accumulates to be the cutting boundary that controls the slope deformation and failure. To understand how the slope stability varies in the process of cracking expanding, upper bound approach is employed to assess the cracked slope in Wenchuan earthquake epicenter considering the effects of crack propagation, rainwater infiltrating and earthquake. The results conducted in this paper indicate that the crack propagation lowly reduces the slope stability and it does not directly destabilize the slope. But the crack length owing to propagation inevitably increases the probability of slope failure, which more depend on the filling water in the crack and the earthquake intensity.

Abstract: Based on the method of level-layer analysis, with the sliding harmonious condition of layered backfills considered , the theoretical answers to the unit earth pressures , the resultant earth pressures and the points of application of the resultant earth pressures on retaining walls with layered cohesive backfills are set up . The comparisons are made with Rankine’s formula.

Abstract: The substantial difficulties are encountered as the huge computation of complex three-dimensional finite element model. Network parallel computing is one of the most compelling topics at the forefront in the current field of parallel computing, the size and the speed of structural analysis can be increased by the combination of both, so that large and complex three-dimensional finite element calculation can be carried out smoothly. According to Wushaoling tunnel, three-dimensional finite element model is established and implement under the support of the finite element parallel computing environment of Deep Comp 1800 cluster system based on the analysis of neural network. The realization of 3D geostress analysis is also depend on the artificial neural network computation program ANNBP and MEBAC, which is an interface program connecting ANNBP and ANSYS. The results show that the computation efficiency is highly improved by the Deep Comp 1800cluster system, the distribution of the initial geostress field is compacted significantly by the faults and there is a vertical extrusion characteristic with the tunnel at the fault zone.

Abstract: The current research was implemented to study the practical unloading stress path that the slope mass experienced during the excavation process, which is very important in the stress and strain numerical analysis. Series of unloading tests were carried out under different confining pressure. During the test process, the minor principal stress was kept decreasing, while the major principal stress was kept unchanged to simulate the stress path in some locations of the soil slope, such as at the top of the slope. The corresponding conventional triaxial compression tests were also carried out as comparison. It is shown that there are many differences between the unloading and loading tests. Through analyzing, the tests results could be applied in the development of unloading constitutive models of excavation soil mass. Also, such unloading tests data are valuable in calibration and verification of the current existing popularly used models.

Abstract: This paper describes design process of foundation of Shanghai Center Tower, the China’s tallest building. The foundation system is piled raft founded on deep deposit of delta of Yangtze River. The geotechnical condition and the design progress including the selection of pile type and bearing stratum, pile capacity, raft thickness, foundation settlement will be outlined. The settlement is an important issue in soft soil area for super-tall building, and the optimized design of pile foundation stiffness to reduce differential settlement is also presented in this paper.

Abstract: The time-space movement feature of landslide was a geological process that landslide mass change from a state to another under the effect of internal and external factors. The ground surface and deep displacement feature of landslide with time and space was a reflection and externalization also a trace record of landslide time-space movement. Particularly, deep displacement of landslide provided direct and reliable evidence for studying space-time motion characteristics of slide. This paper studied on ZhenziLin landslide in Sichuan-Tibet highway, based on monitored deep displacement information of boreholes in landslide. It systematically analyzed time-space movement features and operation mechanic of integral revived area, disturbed deformation zone and foreland slump zone of landslide from the aspects of accumulated or relative displacement and displacement vector etc. of confirming or potential slide plane and hole top at different time. Results obtained provided data and dependence for studying landslide stability prediction.

Abstract: The creep property of cement grouted joint is studied based on creep test and theoretical analysis. Firstly, the multi-stage shear creep test under constant normal stress, joint roughness and cement filled thickness is carried out to obtain the creep deformation. Then the conventional linear Nishihara model is used to fit the test results. Due to the big deviation of the theoretical results from the test, the instantaneous elastic shear stiffnesses under different loading stages are calculated. It is found that they vary with the shear stress. The reasons for the nonlinearity are analyzed. Finally the parameters of the Nishihara model are modified to be nonlinear and fit with the test results showing good coincidence between them. These researches release the creep property of the cement grouted joint, and will provide a good basis for further research considering more influencing factors such as normal stress, joint roughness and cement filled thickness.

Abstract: In conventional soil mechanics method, the soil particle is known as rigid and its size remains unchanged during a compression. With regard to waste landfill, however, the degradation can decrease the volume of solid particle, produce new gases and liquids. Settlement character, excessive settlement and differential settlement of waste landfill might lead to all kinds of pipelines rupture, and then percolate cannot be expelled and result in rising ground water level. This will threaten seriously the stability of the landfill. It is fundamental to the landfill recycle to calculate the stability of settlement after closure of landfill. Based on the landfill site engineering in Langfang of North China, this article explores a new computing method of the landfill settlement with layering filling and organic matter degradation. Different factors influences on settlement are analyzed by the computer numerical simulation to offer evidence to the landfill recycle.