Quantifying the effects of elongation and flatness on the shear behavior of realistic 3D rock aggregates based on DEM modeling

It is significant for industrial production and engineering practice to study the macro and micromechanical behaviors of realistic particles in nature. Based on the rock aggregates database obtained by 3D scanning, this study investigated the effect of particle shape on the shear behaviors of particles by discrete element method (DEM) modeling. First, 1200 rock particle models were acquired by white-light scanning, and the elongation index (EI) and flatness index (FI) of the 1200 particles were calculated. After initial dense samples were created for particles with specific EI and FI values by the isotropic compression method, all the samples were sheared in drained triaxial compression tests under a quasi-static condition. Then, the mechanical behaviors of the samples at the peak and critical states were analyzed. Meanwhile, the evolution of internal mechanical behaviors during the shearing of samples with different EI and FI values was evaluated. Finally, through the analysis of the stress-force-fabric relationship, the underlying mechanism explaining why the macroscale mechanical behaviors of samples were dominated by particle shape was revealed from the perspective of fabric anisotropy.