Study on meso-mechanical behavior of sand based on its 2D geometrical model

A comprehensive study on the meso-mechanical behaviors of sand with its 2D geometrical models was presented in this study. Based on the 2D geometrical models’ database of sand particles, quantitative analysis on the geometrical characteristics of the studied sand particles was performed A new clump generation algorithm based on fewer multiple overlapping circles was provided to accurately model the shape of sand particles, and was used to build the discrete element method (DEM) numerical model of the sand sample for DEM biaxial tests. The macro- and meso-mechanical behaviors of the studied sand samples were systematically analyzed. Deformation was mainly localized in a X-shaped shear zone, in which the particles experienced large displacements and rotations. Development of stress-induced anisotropy in particle and void orientations, as well as the mesoscopic fabric, was significant during the shearing process. Continuous collapse, generation, reduction, and extension of force chains occurred during the shearing process, especially after the peak stress was reached. This led to the fluctuations in the evolution of deviatoric stress and volumetric strain at macroscale, as well as the fabric anisotropy at mesoscale.