Modified Mohr-Coulomb strength criterion considering rock mass intrinsic material strength factorization

Abstract

With the increase of mining depth of mineral resources, the rock mass stress state is being more and more complex. The rock mass show different features, namely, with the increase of hydrostatic pressure, rock mass failure mode turns from brittle tension failure to structure ductile failure and its limit strength also increases. The restriction of minimal principal stress on the initiation and development of microcrack and the change of micro-unit stress state by the intermediate principal stress play a decisive role in the increase of rock mass limit strength. Based on the rock mass failure behavior law under complex stress state and the s 2-dependence on the rock mass strength, we proposed a Modified Mohr-Coulomb (M-MC) strength criterion which is smooth and convex. Finally, the M-MC criterion is validated by multiaxial test data of eight kinds of rock mass. We also compared the fitting results with Mohr-Coulomb criterion (MC). It shows that the new criterion fits the test data better than the Mohr-Coulomb criterion. So the M-MC strength criterion well reveals the rock mass bearing behavior and can be widely used in the rock mass strength analysis. The results can provide theoretical foundations for stability analysis and reinforcement design of complex underground engineering.