Automatic local mesh refinement near shear band

A soil test specimen is subjected to a vertical compression. A hole is present in the down left corner; this hole triggers a shear band. Symmetry boundary conditions are applied, so that in fact the quarter part of a total test specimen is modeled. A Drucker -Prager elasto-plastic model for the material behavior is used.

After the test specimen is compressed, automatic local mesh refinement is applied; the elements with the highest plastic strains are refined. Then the calculation restarts with the new mesh automatically. This refinement + automatic restart is done three times.

The first plot shows the deformed mesh after the three refinements.

The second plot shows the plasticity distribution after the three refinements.

Here is the Inputfile.