J2-deformation-type soil model coupled with state-dependent dilatancy and fabric evolution: multiaxial formulation and FEM implementation

Abstract In this paper, an original J2-deformation type model coupled with state-dependent dilatancy is further extended to a multiaxial stress space. Compared with most existing models, the proposed model only requires ten parameters, which can be easily calibrated, and does not involve any abstruse concepts in elastoplasticity theory. The model is then implemented into ABAQUS through a user-defined subroutine (UMAT), and the capability of the extended model in capturing the mechanical behavior of sand is demonstrated by element tests, including conventional triaxial tests and true triaxial tests. To demonstrate the robustness of the model, two typical boundary value problems are illustrated, i.e., the biaxial compression test and the strip footing test. The model is further incorporated with anisotropic critical state theory to simulate anisotropic soil behavior. The biaxial compression test with smooth and rough boundaries is simulated with the anisotropic model. The results confirm the impact of fabric anisotropy and boundary constraints on the shear strain distributions and patterns of shear bands. The simulation results show the capability of the proposed model, which can be applied in practical analyses and geotechnical engineering designs.