A subloading surface clay and sand model

The mechanical response of natural soils is characterized by a narrow elastic domain, a smooth transition between elastic to elasto-plastic regime, and hysteretic behaviour during cyclic loading. These realistic features can be efficiently intro-duced into an existing constitutive model by reformulating it in the framework of subloading surface plasticity. This unconven-tional elasto-plastic approach is advantageous over other techniques, since it allows to retain some stress history information only by adding an additional constitutive parameter and one hardening rule. In this paper, CASM, a state parameter dependent, critical state model, is reformulated in the framework of subloading plasticity. Several element tests are reported to illustrate the performance of the model.