Progressive failure of soils based on non-local Mohr-Coulomb models

The numerical solutions of softening plasticity model using the ordinary finite element method seriously depend on mesh size. The non-local theory is an effective way to solve this problem. But the existing non-local theory can only be applied in von Mises plasticity model and cannot be used to analyze the progressive failure of softening soils. An improved full implicit stress return iterative algorithm for non-local models is proposed. This algorithm, which can assure whether a Gauss point be plastic state after loading or not, overcomes inaccuracy and instability of the existing algorithms. The non-local theory is extended to the Mohr-Coulomb plasticity model, so that it can be used to analyze geotechnical problems. The numerical solutions of the strip foundation bearing and stability problems of slopes subjected to triangle loads using both the local and non-local models demonstrate that the proposed approach can regularly control the equation and eliminate dependence on mesh size of finite element solutions of softening plasticity.