Composite damage constitutive model of jointed rock mass considering crack propagation length and joint friction effect

Abstract

In order to study the damage constitutive model of rock mass with non-persistent joints in engineering practice, the assumption that the rock mesoscopic elements strength obeys the Weibull distribution function of random, the Drucker–Prager criterion is used as a representation method to describe the strength of the mesoscopic elements, and mesoscopic damage variable is deduced. Combined with the energy principle and the fracture damage theory, the macroscopic damage variable formula is deduced considering the crack propagation length and the friction effect of joint closure in the rock mass. Finally, based on the strain equivalent hypothesis of Lemaitre and considering the coupling of macro and micro defects, the composite damage variables are derived. A macro–meso composite damage constitutive model of rock mass with non-persistent joints is established based on the Drucker–Prager criterion. The theoretical constitutive curves of the model are in good agreement with the experimental constitutive curves of the non-persistent jointed rock masses. The considering effects of crack propagation length and joint closure friction effect are compared with those without considering the crack propagation length and joint closure friction effect, which finds that the former is superior to the latter, and the rationality and validity of the model is verified.