Experimental and Numerical Analyses of Particle Shape Effects on the Mechanical Behavior of Particulate Packs Under Different Loading Conditions

This combined experimental and numerical study examines the effects of different particle shapes on the mechanical behavior of particulate packs under vertical and shear loading conditions. Laboratory oedometer tests (ODT) and direct shear tests (DST) performed on 3D-printed polylactic acid (PLA) spherical particles provide data for calibrating the three-dimensional discrete element method (DEM) models implemented in the particle flow code (PFC3D). This study links the micro–macro behavior to gain insights into the mechanical behavior of different particle shapes, focusing on stress–strain relationships, volumetric and permeability changes, and the evolution of contact networks. The calibrated models compare spherical and non-spherical particles with varying aspect ratios. Results show that interlocking, alignment, and rolling tendencies control particle behavior under different loading conditions. Spherical particles show the lowest compressibility under plane strain loading and the least shear strength, post-peak softening, and dilation under shear, due to their ability to roll and rearrange. Non-spherical particles show higher compressibility under plane strain conditions and higher shear strength with strain-hardening and higher contraction under direct shear, driven by alignment, interlocking, and restricted rotation. The approximate permeability analysis reveals that the higher compressibility of non-spherical packs results in a greater reduction in permeability compared to spherical packs.