Investigations of the effects of particle morphology on granular material behaviors using a multi-sphere approach

This article studies the influences of particle morphology on the behaviors of granular materials at both macroscopic and microscopic levels based on the discrete element method (DEM). A set of numerical tests under drained triaxial compression was performed by controlling two morphological descriptors, i.e. ratio of the smallest to the largest pebble diameter, ξ, and the maximum pebble-pebble intersection angle, β. These descriptors are vital in generating particle geometry and surface textures. It was found that the stress responses of all assemblies exhibited similar behavior and showed post-peak strain-softening. The normalized stress ratio and volumetric strains flatten off and tended to reach a steady value after an axial strain of 40%. While the friction angles at peak state varied with different morphological descriptors, the friction angles at critical state showed no significant variation. Moreover, evolution of the average coordination numbers showed a dramatic exponential decay until an axial strain of about 15% after which it stabilized and was unaffected by further increase of axial strain. In addition, stress ratio q/p and strong fabric parameter ϕds/ϕms were found to follow an approximately linear relationship for each assembly. These findings emphasized the significance of the influences of particle morphology on the macroscopic and microscopic responses of granular materials