Experimental study on the influence of height and dip angle of asperity on the mechanical properties of rock joints

Joint roughness significantly affects the damage areas and peak shear strength of the rock joint. In this study, theoretical analysis and numerical simulations were carried out, and the results indicated that the resistance angles and heights of asperities quantified the damage range and damage degree, respectively, during the shearing process. Direct shear tests and 3D scanning tests were conducted on sets of mortar joint replicas and sandstone joints. By analyzing the test data, several morphological parameters were proposed to quantify the damage zone of the joint surface. Based on these morphological parameters, a new peak shear strength model, involving the effects of the height and dip angle of the joint surface, was constructed. Finally, the new model and previous classical models were compared. Moreover, the new model was used to predict the shear strength of other joint samples as well. The comparison and prediction results revealed that the new model is suitable for effective prediction of the peak shear strength of joints.