A modified three-surface elasto-plastic cap model and its numerical implementation

One of main problems in the numerical implementation of many elasto-plastic cap models is associated with the issue how to handle the corner regions, where loading surfaces intersect in non-smooth fashion. At these points elasto-plastic tangent operators could become singular which would cause considerable numerical difficulties. In this paper we present a modified elliptic cap model in which the surfaces intersect in a smooth manner and in this way there is no need for changing the original model parameters. Several numerical examples are presented which show a very good approximation of soil behavior and an excellent convergence of computed results for all possible stress paths.