A practical 3D elasto-plastic incremental method in FEM based on D-P yield criteria

In this paper, focused on popularly used D-P yield criteria in geomaterials, a new incremental method in which the stresses to be transferred according to normal flow rule are directly derived without forming elasto plastic increment matrix, was proposed. This method converges for either small load steps or large load steps. When very small load steps are used, the method is equivalent to standard elasto plastic incremental method. When large load steps are used, the maximum load applied is lower than limit load in structure, the calculated stress field is an static admissible one. As normal flow rule is satisfied in average, the maximum load is close to limit load. The soltion calculated by the method is on the safe side and close to real solution. The method was embedded into a 3D nonlinear FEM software named TFINE,and overloading analysis was performed on an arch dam.