Influence of Crystalline Structure on Strength Anisotropy of Silica Sand

There is limited literature focused on experimentally investigating the influence of the crystalline structure of particles on the constitutive anisotropy of silica sand. This paper assesses the influence of quartz crystal structure on the constitutive response of synthetic silica cubes and natural silica sand particles using 3D x-ray diffraction (3DXRD), synchrotron micro-computed tomography (SMT), and 3D finite element (FE) analysis. The results of unconfined uniaxial compression experiments on synthetic silica cubes exposed constitutive anisotropy that was caused by the crystal structure of quartz. The 3D finite element (FE) analysis was validated to accurately model the crystal-based constitutive anisotropy in silica particles using the results of the silica cube experiments. Then 3D FE analysis was conducted to study how the change in crystal local orientation of individual sand particles can fundamentally produce anisotropy in the constitutive response of natural sand particles. Both the experiments and 3D FE analysis showed that the crystal structure of quartz essentially causes a directional anisotropy in the constitutive behavior of silica sand particles.