Micromechanical correlation between elasticity and strength characteristics of anisotropic rocks

Abstract

The study sets forth a method upon which the strength anisotropy of rocks can be estimated from particular characteristics of the elasticity tensor. By depicting rocks as assemblies of bonded particles, micromechanical formulation of force distribution and contact deformation in conjunction with a local strength criterion eventually lead to macroscopic elasticity and strength properties with fabric tensor as a mutual microstructural descriptor. As such, knowing the elastic properties of rock, the proposed analytical procedure computes the associated fabric anisotropy, which is in turn used to estimate rock strength anisotropy, thus avoiding its costly experimental determination. The accuracy of the procedure is verified against two available experimental datasets (sandstone and slate rock samples) for which both elasticity and strength characteristics are reported. Comparisons between analytical and experimental results indicate that rock strength anisotropy can be captured realistically only when in addition to contact normal-based fabric, microscopic strength parameters are also directional in character.