Influence of Surface Roughness on the Mechanical Behavior of Granular Material Under Triaxial Shear: A DEM Study

This study investigates the mechanical behavior of glass bead specimens with different surface roughness under triaxial testing using the Discrete Element Method (DEM). The microscopic parameters for the DEM simulation were calibrated by referencing macroscopic triaxial test data, specifically stress–strain relationships and volumetric changes. We examined the evolution of the contact force network by analyzing the contact forces and the coordination numbers. Our findings indicate that a higher coefficient of interparticle friction results in stronger contact forces, but with a reduced coordination number. A detailed analysis reveals that the strong force network with higher friction, characterized by higher contact forces and a greater density of contacts, becomes more predominant in specimens. Quantitative measures of anisotropy further show that the contact orientations, normal forces, and tangential forces become increasingly anisotropic during shear. These micromechanical findings directly link the enhancement of macroscopic shear strength to the underlying evolution of anisotropic force chains, offering microscopic evidence into the behavior of rough granular materials.