Applied Mechanics and Materials Vols. 353-356

Abstract: Excavation of existing bridge abutment cone is different from excavation of foundation pit, and the bridge abutment is also different from the slope. During the course of construction at the cone, the settlement and horizontal displacement come into being, but the disciplines of them are very different from the foundation pit and slope. With the engineering example, the discipline of deformation along the length of excavation area is got by monitoring on the abutment surface. The conclusion can provide basis for the reinforcement design of the excavation area at the bridge abutment cone.

Abstract: Failure and loose powder sand instability, both of which may lead to disastrous results. This is shown in the change of internal stress and the observations of sand stability behavior when on expansion state. Once adopted tradition design method, the slopes will become unstable. The position of unstable line is discussed here and the proposed analysis method is based on the region of the potential instability and the state of stress in the groun.

Abstract: The elasto-plastic waves of solids with dilatancy effect are studied here based on the theory of standard space under physical presentation for anisotropic solids, in which a new yield function is induced, which consider both isotropic hardening and kinematic hardening. The speed equations of elasto-plastic wave in anisotropic solids are deduced, and several new and important results are obtained.

Abstract: Bank slope seepage field is analyzed by saturated-unsaturated seepage theory under the three times cycle conditions of water level rising and drawdown . The pore water pressure distribution laws of the water level rising period, the stabilization period, the period of decline and decline stable period for every cycle are researched. The result shows soil near slope region is saturated easily after many rounds of water level rising and drawdown, and saturation region gradually increases. Soil phreatic line near slope falls fastly in the drawdown period, away from the slope, phreatic line declines slowly.

Abstract: According to the analysis on engineering geological and hydrological conditions of landslide on expressway from Yangshuo to Pingle in Guangxi, the formation mechanism of the landslide was summarized. The stability of slope was analyzed by mechanical transfer coefficient method. Then two kinds of effective preventions and treatment measures are proposed: setting retaining structure after drainage, or unloading after drainage. These measures have reference value to the management of the other landslide.

Abstract: Influence of water content on the resilience modulus for silt soil in Yellow River alluvial plane is studied by laboratory tests. And its found that resilience modulus decrease dramatically when the water content exceeds the optimum. So the subgrade cant support the pavement structure enough, which could make the fatigue life of semi-rigid base little than the design value. Basing on the distribution of the water content in real, the silt subgrade is divided into three parts in accordance with the difference of resilience modulus. Then, the tensile stress and fatigue life of semi-rigid base is gotten, and results show the strength decay of subgrade reduced the fatigue life of semi-rigid base up to 50%, which exposes the causes of early damage of semi-rigid base asphalt pavement on silt subgrade.

Abstract: Based on the strain-holding test by using GDS stress path triaxial apparatus, the changes of pore water pressure and stress of soil around the pile were simulated during and after pile jacking. Test results show as follows: excess pore water pressure and effective stress increment increase with strain and initial stress rising at the stage of strain applied. And at the stage of strain holding, effective stress increment increases with rising of strain and initial stress. For the total effective stress increment, the proportion of effective stress increment is large at the stage of strain applied. And at the stage of strain holding, the proportion of effective stress increment is small.

Abstract: A mechanical model for Sarma method was built based on a sliding of simple non-homogeneous rock slope as the research object. The relationship between the lateral positive pressure on block and the critical acceleration coefficient were gotten according to the rock slope block static equilibrium conditions. Then the critical acceleration coefficient formula was deduced. So that the coefficient of slopes security and stability under the conditions of the earthquake intensity were receieved.By using the functional relation between the slopes security and stability coefficient and the critical acceleration coefficient, a monotonously decreases function relationships between the rock slopes security and stability coefficient and the critical acceleration coefficient drowned by the calculation and analysis was gotten. The results show that, this method does not need iteration when compared with the traditional Sarma method; hence a convergence problem does not exist. It also can simplify the calculation and reduce a large number of calculations, the calculated results can meet the requirements after a number of numerical examples analysis.

Abstract: A bounding-surface model is modified and introduced a state parameterbased on phase transformation state, e.g., when subjected to shear, sand will contract until phase transformation is reached, while, then dilatant until the ultimate where =constants simultaneously. With state parameter the deformation tendency of a sand at any time or any conditions can be judged correctly. As a result the dilatancy depends on the state in a way that yields a zero value at phase transformation state. This dependence allows a realistic modelling of the response of a sand in either loose or dense state, or in the transition from one state to another state. A comparison between model simulations and a sequence of experimental results for drained, monotonic loading conditions shows that the proposed concept and modelling technique work effectively using a unique set of parameters (or parameter dependence) for a given sand.

Abstract: An new intelligent displacement back analysis, named as CACA-SVM, was proposed based on support vector machine (SVM) and Continuous Ant Colony Algorithm (CACA). On the one hand, CACA-SVM used SVM to build the nonlinear mapping relationship between them. On the other hand, CACA-SVM used the global optimization performance of CACA to search the optimal rock mechanics parameters in the global space. The nonlinear mapping relationship built by SVM can fit and forecast the measuring point displacements under different parameters with high accuracy, avoiding the complex numerical calculation. CACA can prevent object function from trapping in local optimum and improve precision of back analysis. Case study shows that the forecasting trend was in good agreement with the measured trend, which indicated that the model was suitable for solving the geotechnical engineering problem of nonlinearity and uncertainty and could well be applied to displacement back analysis.