Modeling Combined Fabric Evolution in an Anisometric Granular Material Driven by Particle-Scale X-Ray Measurements

A combined fabric evolution (CFE) model is used to predict real-world fabric evolution of a strongly anisometric granular material under triaxial loading, connecting advances in theoretical developments and experimental measurement technology for fabric evolution. X-ray tomography is used to quantify particle orientation and contact normal fabric evolution in five triaxial compression experiments on lentil specimens of different initial bedding plane angles. The CFE model coupling contact normal fabric evolution with particle orientation fabric is calibrated based on two of the experiments and used to predict the fabric evolution in the others. Good overall agreement between theoretical prediction and experimental measurement is achieved for the evolution of both types of fabric tensors. The comparison between prediction and measurement highlights an optimistic future for the development of constitutive relations incorporating fabric features based on actual experimental micromechanical observations. Nonetheless, the special case of 90 degrees deposition is relatively poorly predicted due to the strongly heterogeneous local dilation caused by the extreme particle shape and alignment. This suggests that there is still more to be considered in the continuum description of the fabric evolution of granular materials, especially with respect to local information.