The solutions of boundary value problems involving strain-softening material property are full of serious difficulties from both modeling of strain-localization and a viewpoint of numerical procedure. Mesh size-dependent hardening modulus is considered to alleviate the mesh size-dependency of the solution. The elasto-plastic soil model with kinematic hardening model considering the cumulative deformation by cyclic loading is developed. In finite element analyses, the dynamic relaxation method combined with the generalized return-mapping algorithm is applied to the static drained and undrained triaxial tests and plane strain tests. The dynamic progressive failure analysis of rockfill dam is carried out.