Inherent anisotropic rocks, Secondary structural planes, Constitutive model, Crack tensor, Damage tensor, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712

Large-scale and heavily jointed rocks have inherent planes of anisotropy and secondary structural planes, such as dominant joint sets and random fractures, which result in significant differences in their failure mechanism and deformation behavior compared to other rock types. To address this issue, inherent anisotropic rocks with large-scale and dense joints are considered to be composed of the rock matrix, inherent planes of anisotropy, and secondary structural planes. Then a new implicit continuum model called LayerDFN is developed based on the crack tensor and damage tensor theories to characterize the mechanical properties of inherent anisotropic rocks. Furthermore, the LayerDFN model is implemented in the FLAC3D software, and a series of numerical results for typical example problems is compared with those obtained from the 3DEC, the analytical solutions, similar classical models, laboratory uniaxial compression tests, and field rigid bearing plate tests. The results demonstrate that the LayerDFN model can effectively capture the anisotropic mechanical properties of inherent anisotropic rocks, and can quantitatively characterize the damaging effect of the secondary structural planes. Overall, the numerical method based on the LayerDFN model provides a comprehensive and reliable approach for describing and analyzing the behavior of inherent anisotropic rocks, which will provide valuable insights for engineering design and decision-making processes.