The Hoek-Brown Failure Criterion

The Hoek-Brown criterion was developed as a means to estimate rock mass strength by scaling the relationship derived according to the geological conditions present. The criterion is non-linear in the meridian plane and linear in appearance in the plane perpendicular to hydrostatic axis and cuts the failure envelope. By adjusting the frictional strength of the rock and measure of how fractured the rock is according to the rock mass conditions, the criterion can be applied to the estimation of rock mass strength properties. As a peak strength criterion for intact rock, the Hoek-Brown criterion has the advantage of describing a nonlinear increase in strength with increasing confinement that agrees with extensive laboratory triaxial test data covering a wide range of intact rock types.