LAUSR

Abstract Failure criterion is a mathematical relationship with respect to applied stresses on rocks which shows the ultimate strength of rocks. Up until now, different investigations have been devoted for preparation of failure criteria. In this study, grid search and axis changing methods are used to compare various failure criteria for different types of rock with the experimental polyaxial test data. These criteria include; Mohr-Coulomb, Hoek-Brown, Bieniawski-Yudbir, linear, second order and power law form of Mogi 1967, linear, second order and power law form of Mogi 1971, Modified lade, Drucker-Prager, 3D Hoek-Brown, Modified Wiebols and Cook, HBMN and Modified Mohr-Coulomb. Polyaxial data were determined experimentally. The results show that, Mohr-Coulomb, Hoek-Brown and Bieniawski-Yudbir criteria in which intermediate stress is not included on rock failure, have the least accuracy and approximately have the same absolute relative error. Among all the criteria, the Modified Lade results have the best agreement with the experimental data. In particular, the Modified Lade criterion is the best choice for assessing wellbore stability in oil and gas wells drilling industry and mine tunneling.