STUDY ON BRITTLE ROCK FAILURE CRITERION BASED ON STRAINS
基于应变的岩石类脆性材料损伤研究

When rocklike materials are tested in triaxial compression,two kinds of failure,ductile failure and brittle failure,may happen. Rock failure essentially results from the relative displacement among mineral particles. Generally,rock failure can be either tensile or shear,depending on which mechanism is predominant during the failure process. The maximal tensile strain criterion can predict rock failure in tension,but cannot explain the crack angle. Rocks are generally anisotropic. The principal strain axes are usually different from the loading axes. Therefore,strains in the directions of the loading axes may not be suitable to describe rock strength. The strain-based strength criterion considering tensile strains in three axes can describe rock strength. And it can describe the crack angle and its transformation. Theoretical analyses and laboratory tests have validated this conclusion. With the increase of the intermediate principal stress,the transformation of the strain failure criterion is of the same pattern as the transformation of the compressive strength criterion and the maximum tensile strain criterion.