Abstract: Considering the Drucker-Prager constitutive model under Cosserat continuum theory, the finite element analysis of slope stability is conducted by coupling the characteristics of strength anisotropy and strain softening of soil. Numerical simulation is carried out by the secondary development of finite element software ABAQUS, and then the slope stability analysis is conducted based on the gravity increase method. The method of microstructure tensor combined with stress invariant is used to consider the anisotropy of cohesion, which is compared with the classical Casagrande anisotropy method commonly used in slope stability analysis. It is proved that the method of microstructure tensor combined with stress invariant is more reasonable in theory and numerical analysis. By simulating the relevant examples, it is found that strength anisotropy and strain softening have great effects on the overloading safety factor of the slope, especially when the slope angle is slow. The comparative study demonstrates that it is difficult to obtain the reliable overloading safety factor by the classical continuum finite element analysis coupling strength anisotropy and strain softening, and there is an obvious mesh-dependent defect. However, the Cosserat continuum finite element analysis can effectively overcome these problems and maintain the well-posedness of strain localization caused by the strength anisotropy and strain softening. Thus, the effective results are obtained.

Key words: strength anisotropy, strain softening, slope stability, gravity increase method, Cosserat continuum