Estimation of micromechanical strength of brittle rocks under compression

Abstract

A unified micro-macro method is proposed to estimate short-term, long-term, and shear strength of rocks under compression. This method is formulated by combining the wing microcrack model, subcritical crack growth law, Mohr–Coulomb failure criterion, and crack–strain relation. The short-term strength is predicted by the theoretical stress–strain relationship caused by microcrack growth. The stress states for a given creep failure time and long-term strength are analyzed using the proposed theoretical three-level creep evolution relationship. Moreover, the shear strength is reviewed by the proposed predictive method for shear failure. Correlation of short-term, long-term, and shear strength is closely analyzed, and the effects of crack size, crack friction, and fracture toughness on short-term, long-term, and shear strength are discussed.