Modified explicit scheme of return mapping integration algorithm on rotational hardening constitutive model for clay

Natural clay soils due to anisotropy have a different behavior from disturbed and remolded specimens. The Modified Cam Clay (MCC) model,as a fundamental critical state model,cannot capture this behavior with enough accuracy. However,anisotropic models that known as rotational hardening models can efficiently simulate the anisotropic behavior. Specifically,SANICLAY model,which has been recently developed,has a high accuracy in modeling of the anisotropy and thus is used in the present study. Here,a semi-explicit constitutive integration scheme is proposed and validated for the SANICLAY model. It is then implemented in FLAC software through a UDM subroutine. Several triaxial simmulations are carried out and the results are compared with the MCC model results. Advantages of the proposed integration method in terms of stability,accuracy and speed are discussed.