ABSTRACT
The behavior of rock joints under shear loading depends upon not only the friction between joint surfaces and the joint material strength, but also the geometrical profile of the joint surface. The shear strength of a rock joint is the combination of the shear resistances provided by these two mechanisms. The shear resistance in the first mechanism depends on the basic friction resistance between joint surfaces, and the dilation during shearing. Results of laboratory shear tests on various joint surfaces were compared with the calculated shear strengths. Comparisons were made between the predicted shear strengths and the results of laboratory direct shear tests on man-made plaster joint profiles, tension joints obtained in the Brazilian test on the rock cores, and natural rock joints. The scale effect and the effect of shearing direction on the shear strength of a joint can also be considered in this model.
