Shear Strength of Rock Joints and Its Estimation

This study examined the shear behavior of rock joints and proposed an analytical model for estimating the shear strength at rock joints. Numerous experimental tests indicated that the shear behavior at rock joint depends on many factors including the distribution of initial joint asperity, asperity angle and strength, applied normal stress, and progressive degradation of asperity. Nevertheless, most pre-existing strength models do not consider these features on shearing at rock joints enough. In this study an improved shear strength model, which can consider the complex joint shearing features observed from many experimental tests, was developed and proposed. The improved model considers the joint features more reliably and overcomes the limitations of the pre-existing strength models. The proposed model was compared with some experimental test results along with some pre-existing strength models. The comparison clearly indicated that the improved model can estimate the shear strength at rock joints more reliably than the pre-existing models. From the study results it is expected that a better estimate of joint shear strength could be obtained in the future for various rock, joint, stress, and shearing conditions.