Novel 3D Failure Criterion for Rock Materials

Abstract

The failure criterion of rock material has been used in geotechnical engineering to assess the failure behavior of rocks under complicated stress conditions. In the present study, a new failure criterion is proposed; it takes into consideration the influence of intermediate principal stress for rock materials. The general characteristics of failure surface were analyzed, showing that the failure envelopes are convex and smooth everywhere except at the triaxial compression and triaxial tension conditions. A new shape function is presented to approach the failure criterion in the deviatoric plane, and the smoothness and convexity of the criterion is discussed. The new failure criterion is compared with some classic criteria by cross-sectional failure envelopes in the π plane and meridian failure envelopes in the meridian plane, and the advantages of the new three-dimensional (3D) failure criterion are presented. The results show that the new criterion not only inherits the strength characteristic of the Hoek-Brown failure criterion at the triaxial compression condition, but it also predicts failure stress better than other 3D failure criteria for rocks under complicated stress states.