Micromechanical Modeling for the Deformation of Sand with Noncoaxiality between the Stress and Material Axes

Abstract

Within a micromechanical framework, a constitutive model for sand capable of predicting noncoaxiality between stress and strain increments is presented. Anisotropy of elastic and plastic material properties is considered by introducing fabric-like second-order coefficient tensors that arise from a description of the interparticle contacts of sand grains. Strength anisotropy is further accounted for by introducing an interlocking parameter that describes the relative ease of sliding depending on the orientation of potential failure planes. The model is calibrated to and validated against two sets of hollow cylinder triaxial compression experiments consisting of various orientations of major principle stress directions, including tests conducted with the principle stress axes noncoaxial with the material axes. Model predictions of noncoaxiality between stress and strain increments are examined and compared with laboratory measurements. The results show that by considering the arrangement of interparticle contacts, the model is capable of predicting such noncoaxiality without the need to specify a priori any assumptions about the noncoaxial behavior.