Particle shape effect on the shear banding in DEM-simulated sands

Particle morphology is an essential characteristic that plays a crucial role in determining the mechanical responses of granular materials. A series of discrete element method (DEM) simulations of a mini-triaxial test were conducted, focusing on the shear behaviours of granular material. To mimic the physical testing situation, DEM simulations were combined with micro-computed tomography, and image processing techniques and spherical harmonics analysis were utilised to reconstruct realistic particle morphology. The multisphere clump method and flexible-membrane technique were used to simulate three types of sand and allow flexible deformation in the radial direction. The numerical results show that the grains inside the shear band rotate more freely and exhibit obvious fabric anisotropy. The shear behaviours are strongly associated with the shape of the component particles. Specifically, with the increase in shape irregularity, the stiffness and peak deviatoric stress increase, and a more obvious dilation is observed during shearing. In addition, with particles ranging from regular to angular, less particle rotation and more intense fabric anisotropy occur. The numerical investigations highlight the significant role of particle morphology in the shear behaviours of granular materials.