Abstract: When the conventional strength reduction finite element method is used to determine the plastic zone of slopes, the results obtained are not so accurate, the shape of plastic zone and the position of sliding surface can not be directly visualized. Using the method of local mesh refinement around the plastic zone, one can not only improve the accuracy of the safety factor calculated greatly but also solve the shape and position of sliding surface. For the specific problems of searching the sliding surface in the plastic zone, a plastic strain limit is presented as a mesh refinement criterion. The shape and position of the sliding surface and the safety factor is determined by local mesh refinement method. A lot of numerical computations are carried out, the results have shown that the criterion used is effective for determining the shape and position of the sliding surface, and the error of the safety factor between the computed value and the accurate value is only 0.2 %.

Key words: slope stability, adaptive local mesh refinement, finite element method (FEM), shear strength reduction (SSR), safety factor, sliding surface