A Hoek–Brown Model–Based Failure Criterion for Characterizing Strength Behavior of Anisotropic Rock

Abstract The presence of a bedding plane within rock has an important influence on the strength and failure behavior of anisotropic rock. Results from previous studies have shown that the strength behavior of anisotropic rock containing a bedding plane is different from that of intact rock, leading to a high discrepancy in the failure criterion. The purpose of this study is to propose a modified failure criterion based on the widely used Hoek–Brown (H-B) model for characterizing the strength behavior of anisotropic rock. Triaxial compression tests are first conducted on the rock specimens containing a bedding plane with different angles. The strength and failure characteristics of the tested rocks are comprehensively examined. A new failure criterion in the framework of the generalized H-B model is then proposed by quantitatively establishing a relation between geological strength index and bedding plane angle. Last, a huge amount of test data of various anisotropic rocks from previous studies are collected and used to validate the proposed model. The results show that the proposed failure model can satisfactorily capture the strength evolution of anisotropic rocks possessing bedding planes with different angles. A sensitivity analysis of model parameters is also conducted, which is useful for determining parameters in the proposed failure criterion for various anisotropic rocks.