The Micro Damage Model of the Cracked Rock Considering Seepage Pressure

Abstract

The damage constitutive model and the evolution characteristics of the cracked rock, considering seepage pressure, are critical to the stability of the cracked rock engineering. Based on the Rice Theory of Thermodynamics and the friction-bending crack model, we proposed the damage evolution model for the cracked rock in the compressive-shear state, considering the seepage pressure, the initial damage of the cracked rock, and the accumulated damage caused by crack evolution. According to the influences of the normal deformation and the branched crack (caused by the seepage pressure and the normal stress) on the opening of the crack, we established an evolution equation for the seepage tensors with the accumulation of the crack damage. In addition, based on the visual development platform, VB 6.5, we developed the software, WFRD2D, to comprehensively calculate the nonlinear damage deformation, the strength and the seepage indexes of the cracked rock, subjected to seepage pressure. Then, we obtained the pre-peak stress–strain curve of the cracked iherzolite rock using WFRD2D. The results show that the rock strength decreased by 48%, whereas the lateral strain increased by 240%, considering the seepage pressure of 3 MPa. These phenomena indicate that seepage pressure damages the cracked rock, then, further decreases the rock strength and increases the lateral strain. Thus, the seepage pressure significantly affects the mechanical properties of the cracked rock.