Hoek-Brown failure criterion - a 1988 update

Abstract

The brittle failure criterion for rock, described by Hoek and Brown (1980 a,b) and Hoek (1983), is widely used for estimating the strength of jointed rock masses. Publications describing applications of the criterion and correspondence received by the authors suggests that there is confusion on some of the details of the criterion and upon its limitations. This paper gives a briersummary of the equations which define the failure criterion in terms of major and minor principal stresses and normal and shear stresses and then discusses approximate relationships between the constants m and s and the rock mass classification developed by Bieniawski (1974) for both disturbed and undisturbed rock masses. Limitations on the use of the criterion and guidance on the selection of the the empirical constants are discussed in the final section of the paper.