Influence of debris shape on the mechanical behavior of breakable granular materials under confining pressure

Abstract

The mechanical behavior of the granular materials is significantly affected by debris shape caused by particle breakage. In order to reveal this mechanism, the discrete element method is employed to investigate the effect of debris shape on particle mechanical behavior under different confining pressure. A breakable particle model with realistic external shapes but different debris shapes is constructed, and a series of drained triaxial tests are conducted under varying confining pressures. The macroscopic characteristics of the particles, including the degree of particle breakage, shear strength, and deformation properties, were evaluated. Additionally, the microscopic origins of peak and critical shear strength, as well as deformation characteristics, are discussed from the perspectives of fabric anisotropy and particle motion. Regarding anisotropy, the strength differences between different debris shapes at the peak state are mainly reflected in a_c, a_n, and 1.5a_t. The differences are magnified in the critical state, primarily due to the increasing disparity between a_n and 1.5a_t. Regarding particle motion, as the confining pressure increased, the average displacement of particles decreased. This phenomenon primarily is driven by the decrease in the number of sliding particles, while particle rotation also contributed to some extent to the reduction in displacement. Furthermore, particle motion exhibits a strong correlation with the deformation mechanisms in granular materials. Smaller average displacements lead to shrinkage behavior in the particle assembly, whereas larger displacements result in dilative behavior.