Abstract: Based on the strength reduction method of finite element method, the elastoplastic material nonlinearity and large deformation geometrical nonlinearity of the slope are studied; and three dimensional deformation features of the slope are also considered. In the finite element analysis, the realistic elastoplastic model of Mohr-Coulomb is adopted; and the method for describing the large deformation characteristic of the soil is updated Lagrangian method. Through analyzing a homogeneous slope, it’s concluded that there exists the same rule among the results of the finite elements and simplified Bishop method. The rule is that the factor of safety will become large if the cohesion and the internal friction angle become large, and it will become small with the increase of unit weight. However, the results of the finite element methods are always larger than the corresponding value of the simplified Bishop method, which means that the result of simplified Bishop method is inclined to conservative. The decreasing order of the four kinds of results of safety factor is Fs (three dimensional small deformation), Fs (two dimensional large deformation), Fs (two dimensional small deformation) and Fs (simply Bishop Method); among them the first two methods are the best one and their values are very close each other.

Key words: slope stability, finite elements, strength reduction method, material nonlinearity, geometrical nonlinearity