Comparison of Two Strength Criteria for Intact Rock

Abstract

Two broadly based empirical strength criteria have recently been proposed for intact rock. The first, which applies to intact rock and rock masses was presented by Hoek and Brown in 1980. The second, which applies to all intact geomechanical materials ranging from slightly overconsolidated clays to hard rocks, was presented more recently by the writer. It is demonstrated that the two different criteria predict essentially the same variations in strength when each is applied to the material of common interest, namely relatively hard intact rocks.