Stability Analysis Method Based On The Strength Reduction Slopes

In this thesis, the shear strength reduction technique is used to study the stability of slope, and the safety factor of slope is the ratio of the shear strength reduction which the soil shear strength divided by that of the employed when the failure using reduced shear strength, and it has the physics mean as a strength reserve factor.Evaluation of the stability of slope is based on the finite element method (FEM) and the finite difference method (FDM). In FEM the soil is modeled as a nonlinear Duncan E-B material or elastic perfectly plastic material with a generalized Mises yield criteria; and in FDM as a elastic perfectly plastic material with a Mohr-Coulomb yield criteria. The application of strength reduction technique in all numerical method and the method of getting safety factor and failure surface of the slope is developed.The definition of "failure" criterion of the slope is discussed, and the result that bases on different failure criterion is analyzed. It can be find that the criterion, which is basing the displacement of the slop top, can get the reasonable result, it has the clear physical meaning and the objective explicitly, easily to implement in analysis.The safety factor is related to the yield criterion in the FEM, this paper presented a comparison of several generalized Mises yield criterions in common use, and deduces the general express under the plane strain condition.The parameter sensitiveness analysis has been done using the orthogonal test method. Soil parameter's infection on the safety factor was discussed by the shear strength reduction method. Except the cohesive force and frictional angle, the effect is visible for the safety factor when the elastic modules, poisson's ratio and dilation angle of the soil are varied in a certain extent, specially the dilation angle.The example of strength reduction stability analysis with all numerical method is presented. In these studies, it is fond that the safety factor using shear strength reduction method is fairly close to the result of traditional limit equilibrium method and the sliding curve of this method is coincident with these basically. So the shear strength reduction method is reasonable for stability analysis of the slopes.