NUMERICAL ANALYSIS FOR FAILURE MODE AND ULTIMATE BEARING CAPACITY OF STRIPING FOOTINGS ON CREST OF UNDRAINED SLOPES

This paper estimates the ultimate bearing capacity of foundations on the slope crests. It uses the elasto-plastic finite element method(FEM).It simulates the striping footings on the crest of undrained slopes (u=0). The results show that the ultimate bearing capacity can be expressed as qu=cuNc. When the unit weight of soil is ignored, Nc estimated by FEM is highly agreeable with that calculated by limit analysis. The failure mode is similar to the foundation on the horizontal terrain. When the unit weight of soil is taken into account, the coefficient Nc can be reduced more. The parameter N is defined as the difference of the slope's stability number defined by Taylor from the slope's real state to the limit state. It can be used as determinant. The striping footing's failure can develop into whole slope failure when the N is smaller, as well as foundation failure when the N is bigger. The critical value of N for failure mode change is estimated. Then the Nc-N relationship is constructed. The equation for the ultimate bearing capacity of striping footings on the crest of undrained slopes is built.