Study on Mode I–II hybrid fracture criteria for the stability analysis of sliding overhanging rock

Abstract

Overhanging rock is widely distributed in mountainous regions of the world and therefore poses a potential geohazard to life and property because of fracturing and, ultimately, failure. The maximum circumferential stress criterion is widely used in fracture mechanics. However, it is inadequate with respect to predicting the failure of sliding overhanging rock that is subject to extension and shear fracturing. In this paper, the maximum shear stress at a crack tip and a fracture method in combination with the Mohr–Coulomb criterion are used to examine rock with mixed Mode I–II fractures. The methods are ultimately used to analyze the stability of sliding unstable rocks. The two fracture criteria have been compared according to the most unfavorable conditions, and the stability of the sliding rock masses are calculated using these new fracture criteria in two case studies. The calculations show that the rock stability calculated by the comprehensive fracture criterion is very close to that calculated by the limit equilibrium method, but in addition, the two methods can also determine the fracture angle. Overall, the maximum shear stress approach and a fracture mechanics criterion based on the Mohr–Coulomb model are more suitable than the limit equilibrium method for evaluating the stability of sliding overhanging rock.