A comparison between common empirical failure criteria for rock masses

Predicting the rock mass strength in different stress or strain conditions is necessary both in numerical simulations and theoretical analyzes. This is usually done using one or some forms of failure criteria. Different failure criteria are introduced in recent decades for rock masses. These criteria are stress and/or strain dependent. The mostly used rock mass failure criteria however, are those which are stress dependent. On the other hand parameters which describe the rock mass properties are also included in these criteria. The variety of these criteria and parameters lead to confusion if not erroneous results. The aim of this study is to present a comparison between seven common rock mass failure criteria .These include Modified Mohr- Coulomb, Generalized Hoek-Brown, Sheorey, Yudhbir, Ramamurthy, Bieniawski-Kalamaras and Lundborg criterion. For three types of rock mass quality the prediction of each criterion in forms of principle stresses are calculated and compared. The results showed that Modified Mohr-Coulomb criterion and Generalized Hoek-Brown criterion have the same trend in σ₁-σ₃ space for various quality rock masses but with different values. Modified Mohr-Coulomb criterion and Lundborg criterion have also the same shape in τ-σ space for various quality rock masses again with different values. Ramamurthy criterion is more conservative related to other five criteria for various quality rock masses.