Stiffnesses and shear strength of rock joints

The joint fabric is stiffnesses of rock joints which are required for assessing the deformability and strength of the jointed rock mass to predict the settlement of rock structures. For the numerical analysis, the stiffnesses of rock joints are required which can be found out from in-situ shear tests. The angle of shearing resistance decreases as the level of normal effective stresses increases. At higher normal stresses, failure occurs in a very complex manner by ploughing, shearing through the ridges and fracturing of the rock material adjacent to the contact. If the normal effective stress is large enough, all dilatancy would be suppressed and the rock discontinuity would shear at nearly a constant volume. In this paper, it has been shown that the similar failure law can be derived for rock discontinuities from in-situ shear tests on rock joints with non-rigid asperities and stiffnesses of rock joints are also presented.