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Micromechanical modeling for the deformation of sand with non-coaxiality between the stress and material axes

Within a micromechanical framework, a constitutive model for sand capable of predicting non-coaxiality 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 inter-particle 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 non-coaxial with the material axes. Model predictions of non-coaxiality between stress and strain increments is examined and compared with laboratory measurements. The results show that by considering the arrangement of inter-particle contacts, the model is capable of predicting such non-coaxiality without the need to specify a priori any assumptions about the non-coaxial behavior.

Author(s):

Kane Bennett    
Stanford University
United States

Ching Chang    
University of Massachusetts Amherst
United States