DEM Investigation on the Evolution of Fabric under True Triaxial Conditions in Granular Materials

Abstract

The evolution of fabric under loading plays an important role in the micromechanical analysis of granular materials. This paper addressed this issue from the perspective of the discrete element method (DEM) simulation. A series of drained tests were performed under true triaxial stress conditions. Isotropic assemblies with different densities were sheared to the critical state under three kinds of loading paths. The evolution of three-dimensional fabric under general stress conditions was investigated by analyzing the influences of density, shear mode, and loading path on the fabric anisotropy. Numerical results revealed some evolution patterns of fabric with strain and stress. The evolutions of fabric components and deviatoric fabric were dependent on shear mode. An ultimate fabric anisotropic state was achieved at a relatively large strain for a given shear mode, which agreed with the theoretical expectation of anisotropic critical state theory. Noncoaxialities between fabric, stress, and strain tensors were also observed in simulations and these noncoaxialities needed to be rationally incorporated into fabric evolution laws.