Failure behavior of rocks at ambient temperature

Abstract

This paper presents the results of triaxial loading experiments performed to determine the fracture strength characteristics of granite subjected to truly three-dimensional loading. These measurements were carried out on thin walled, hollow cores which were subjected to various tension-torsion, and compression-torsion loading paths in the presence of confining pressures of up to 48.3 MPa (7000 psi). The results were compared to the predicted values using the classical theories of Coulomb-Mohr and Drucker-Prager. It was observed that none of the above criteria were able to closely predict the failure over the entire range of stress states. Also, the experimental results of other investigators on the failure of Solenhofen limestone, sandstone, marble, and shale were compared with the failure criteria of Coulomb-Mohr and Drucker-Prager. It was then demonstrated that both of these criteria were effective in predicting rock failure for only lower values of 1 2 (σ 1 + σ 3) or J 1 . At higher values of J 1, the above criteria were relatively less effective in predicting the failure of rocks.