Capability of a rational function as rock failure criterion considering brittle-ductile transition

Abstract

A rational function is proposed as a failure criterion for isotropic, dry and intact rocks to be used in both tensile and compressive regions. The criterion is capable of predicting the triaxial behavior of rock under low confinements satisfying the exact values of uniaxial tensile and compressive strengths. The capability of the rational criterion is assessed by applying brittle-ductile transition and downward concavity boundary conditions into the criterion introducing ë and ã parameters. The sensitivity of the criterion response is analyzed by varying under variation of ë and ã parameters. It has been shown that the Hoek's rule of thumb for brittleductile transition could be used for all types of rocks in low confinements and the proper boundary between low and high confinements is obtained. It was also experimental that the acceptable envelope could be obtained for low confinements using a dataset including only two triaxial tests together with uniaxial tensile and compressive strengths. Also, the parameters and concavity of the criterion have been discussed. © ISRM International Symposium - 5th Asian Rock Mechanics Symposium 2008, ARMS 2008. All rights reserved.