Shear Strength Behaviour of Jointed Rock Masses

Abstract

Rocks encountered in civil and mining engineering structures are generally jointed in nature. The presence of joints renders anisotropy in rock and makes them weaker in their engineering response. Assessment of shear strength response of such jointed rocks, subject to given stress state, is a challenging task. Large size field tests are very expensive and time consuming and hence not feasible for majority projects. The best alternative available is to use indirect methods to describe the shear strength behaviour of jointed rocks.

The present articles presents some of the most widely used techniques developed during last few decades, using which the shear strength response of jointed rock can be assessed with reasonable accuracy. Relatively simple tests and observations are required for applying these techniques and hence input data can be procured without much difficulty. The shear strength response is divided into two broad categories i.e. strength behaviour of joints and strength behaviour of jointed rock mass. Shear strength models described in this article cover linear as well as non-linear strength response. Classification systems are widely used to characterize the rock masses in the field. It has been explained, how, these classification systems could be used to assess the shear strength response of the rock masses.