A general failure criterion for geomaterials with cross anisotropy

The strength of soils and rocks is greatly influenced by cross anisotropy which cannot be properly characterized by an isotropic failure criterion. A novel anisotropic failure criterion is proposed for geomaterials in this paper. To account for the influence of cross anisotropy, an anisotropic variable defined by the invariants and joint invariants of the stress tensor and the fabric tensor is introduced into the expression of the criterion. We formulate the new anisotropic failure criterion in both the deviatoric plane and the meridian plane, which collectively lends a general three-dimensional description for the strength anisotropy. All parameters in the criterion can be conveniently determined by conventional laboratory tests. By comparing the model predictions with experimental data, we demonstrate that the new criterion is general and robust enough to characterize the strength anisotropy for a wide range of materials, including clays, sands and rocks. Further extension of the failure criterion for constitutive modeling of geomaterials is discussed.