Study on the Initiation of Interface Crack in Rock Joints

The interfacial fracture of rock joints is an important although easily ignored issue in jointed rock engineering. To conduct this study, an interface crack model of rock joints was proposed. By analyzing the ratio of stress intensity factor to fracture toughness, the fracture mode of the interface crack was studied. Based on the Mohr-Coulomb criterion, an interface fracture criterion considering T-stress was established. To verify the proposed fracture criterion, laboratory and numerical tests were conducted. Finally, the effect of relative critical size alpha, internal friction angle phi and cohesion c on the initiation of an interface crack was comprehensively discussed. It is concluded that the proposed fracture criterion can predit the initiation of the interface cracks properly. With an increase in cohesion c, mode II fracture toughness K-IIC also clearly increases. When the absolute value of K-I is small, the effect of alpha is much larger than that of phi. In addition, with an increase in the absolute value of the mode I stress intensity factor, the phi of the joint plays a more important role in the initiation of the interface crack.

Automated summary

The interfacial fracture of rock joints is an important issue in jointed rock engineering that is often overlooked. This study proposes an interface crack model and establishes an interface fracture criterion considering T-stress. The proposed criterion is verified through laboratory and numerical tests, and the effects of α, φ, and c on the initiation of interface cracks are comprehensively discussed.