Theoretical analysis of the triggering condition of class-II rock behaviors

Mechanical response with a snapback (class-II behavior) is one of the basic features of brittle rocks. This technical Note presents analytical studies on the critical condition which separates the class-I and class-II rock behaviors. Formulations under conventional triaxial compression are performed by making direct use of the closed-form solutions of the damage-friction coupling constitutive equations for microcracked solids. It is shown from theoretical viewpoints that class-II behavior must present when rock is brittle enough and that the triggering condition can be characterized via the critical damage at failure. Moreover, in the class-II response, two transition points present in stress-strain curves, which coincides with experimental observations upon brittle rocks. An energetic explanation is given for the mechanism behind nonlinear dissipative phenomena.

Automated summary

This technical note presents analytical studies on the critical condition that separates class-I and class-II behaviors of brittle rocks. The results show that class-II behavior occurs when the rock is brittle enough, and the triggering condition can be characterized by the critical damage at failure. The study also provides an energetic explanation for the mechanism behind nonlinear dissipative phenomena.