DEM study on the effect of roundness on the shear behaviour of granular materials

摘要

This report investigated the effects of irregular particles on macroscopic and microscopic behaviour under triaxial compression tests for a range of various roundnesses. A multi-sphere method was employed to model the three-dimensional irregular particles generated by rotation-invariant spherical harmonics. After being prepared in the densest conditions, all assemblies were subjected to axial compression until a critical state was reached. The macroscopic characteristics, including the shear strength and dilatancy response, were investigated. We found that the shear strength generally decreased and the volumetric strain linearly and monotonically decreased with increasing roundness. Then, the microscopic characteristics, including the coordination number, particle rotation and percentage of sliding contacts, were examined. An increase in the coordination number obstructed the rotation of particles and led to an increase in the percentage of sliding contacts. Finally, analysis of the related anisotropy coefficients of the entire contact network was carried out to probe the microscopic origins of macroscopic behaviour. A detailed analysis revealed the microscopic mechanism of the dependence of the peak and residual shear strengths on roundness.