Shear-Induced Pore Evolution in Granular Materials: Micromechanical Effects of Stress Path, Particle Shape, and Packing Density

Abstract Understanding the microstructural evolution of granular soils under different loading conditions is essential for linking grain-scale mechanisms to macroscopic behavior. This study introduces a combined discrete element method and image analysis framework to investigate the evolution of pore space characteristics in granular assemblies. Using 3D discrete element method simulations, assemblies of spherical and ellipsoidal particles with different initial densities are sheared under three commonly encountered drained stress paths: axisymmetric compression, axisymmetric extension, and plane strain. A 3D image-based analysis is employed to segment the pore space and extract individual pore characteristics at different strain levels. Results show that stress path, particle shape, and packing density significantly affect the evolution of pore morphology and pore fabric anisotropy during shearing. Comparisons between pore orientation fabric and other structural measures, such as particle orientation, contact normal, and contact force direction, reveal strong interdependencies that evolve with strain level. This study provides new insights into how particle-scale rearrangements and loading conditions govern the development of pore-scale anisotropy, with implications for understanding and modeling the hydromechanical behavior of granular soils.