Simulation of crack propagation in rocks by XFEM

Understanding the failure mode and crack propagation in rock can provide useful information for safe and economic design of various structures in rock. Many researchers have developed theoretical criteria for rock failure with crack growth based on experimental observations. Numerically using cohesive zone model for brittle material with an assumption of some plasticity is found to be a good approach to predict the crack growth in rocks. The cohesive zone model is popularly used for fracture simulation in brittle materials, uses traction-separation law. The traction-separation law represents the material damage zone in front of the crack tip where the material elements are pulled apart. The extended finite element method (XFEM) enhanced the capability of the classical finite element method capturing the crack propagation problems. The important feature of XFEM is that, it can extend the crack without any remeshing which makes it suitable for fracture process analysis. The present paper combines XFEM approach with cohesive zone model (CZM) to analyze the crack growth for rock using ABAQUS. The results of the analysis are compared with the experiments carried out in the laboratory and with available literatures on crack growth in rocks. The present paper demonstrates different crack types (tensile/shear) that gets initiated from the pre-existing flaw with respect to the applied loading. The numerical model using ABAQUS shows a good agreement with the theoretical and experimental results while predicting the crack propagation.