关键词: 土坡稳定, 强度折减有限元, 相对网格大小, 失稳判据, 临界滑动面

Abstract:

Some problems have not still been solved smoothly in slope stability analysis using shear strength reduction finite element method (SSR-FEM) until now. The effect of mesh shape, size and order on the factor of safety is systematically discussed at first; triangular second-order element is thought to be the optimal one, as it can be able to both simulate the failure process of slope and obtain the accurate solutions during the relative element size from 0.1－0.15. When a slope arrives at the critical failure state by SSR-FEM, the four failure criteria as plastic zone extension from the toe to the top of slope, equivalent plastic strain exceeding a certain value developed along the potential slip surface, uncontrollable increase in characteristic nodal displacement on slope surface; and the iteration non-convergence of nonlinear FEM numerical calculations can be found in turn. Calculation results show that the four evaluation criteria are highly consistent. Location of potential slip surface and out-slip point is associated with cohesion, internal friction angle and slope angle. The bigger cohesion, smaller friction angle or the lower slope angle can make slip surface deepen, and the out-slip point is far from the slope toe.

Key words: slope stability, shear strength reduction finite element method, relative mesh size, failure criteria, critical slip surface