Shear Modulus Degradation and Its Association with Internal Damage in Cemented Granular Material

Abstract

Cemented granular material is featured by the presence of inter-particle bonds. In mechanical loading, bond breakage results in a transition from an intact state to a fully disturbed state. However, it is impossible to directly track and measure the breakage of each individual bond among the millions of bonds in a small sample. This study applied discrete element method simulation to associate the evolution of a micro-scale-based damage variable with the degradation of measurable shear modulus in cemented sand. The simulations show that bond breakage is highly non-uniform in a sample. As a result, the sample is deteriorated by the detachment of particles from the main skeleton and the detached particles are found to take no load in the initial stage. This explains the observed sharp degradation of shear modulus. With further bond breakage, the skeleton is disassembled into assembly of particle-clusters, but the shear modulus only varies slightly. The implication for establishment of a physically robust constitutive model for cemented sand is discussed.