Application of Particle Stiffness Fabric Tensor for Modeling Inherent Anisotropy in Rocks

Abstract

The mechanical behavior of geo-materials depends on the assemblage structure and fundamental characteristics of constituting particles such as their shape, size and mechanical properties. Anisotropy is an intrinsic macroscopic material property that quantifies the differences in mechanical resistances to loading directions. In this study, the discrete element method (DEM) is used to investigate the anisotropic behavior of geo-materials like rocks. The model considers a fabric tensor characterizing the internal structure of particles associated with the anisotropy. The new fabric tensor proposed in this research is termed the particle stiffness fabric tensor (P-S fabric), which associates the stiffness (k in the traditional DEM) with the anisotropic state parameters. The results show that the discrete nature of the proposed approach allows an effective modelling of the anisotropic behavior of rocks. Numerical experiments are conducted on standard Brazilian tensile strength (BTS) tests with different anisotropic configurations using the PFC2D code. The tensile strength obtained shows that the results based on the proposed particle stiffness fabric tensor have a much better agreement with experimental results compared with conventional numerical modelling approaches.