A configurational stress-based model to predict mixed-mode fracture of rock under different environments

Abstract

This paper investigates mixed-mode fracture in rock under different environments. The principle of energy conservation provides a clear physical interpretation of the configurational stress tensor, revealing that its components represent the change in total energy induced by material element translation. The Mohr–Coulomb yield function is employed to define the boundary of crack-tip plastic zone. A novel configurational stress-based Mohr–Coulomb yield function is proposed, enhancing the accuracy of plastic zone size and shape assessment. Additionally, a fracture criterion is developed based on the local properties of the crack-tip plastic zone, and then the time factor of Burgers body is incorporated to elucidate the rheological fracture properties of rock. Utilizing this fracture criterion, the impacts of drying–wetting cycles, heating–cooling cycles, thermal treatment and chemical corrosion on rock fracture are investigated. The proposed fracture criterion accurately predicts crack initiation angles and fracture loads, aligning with predictions of the maximum tensile stress criterion and experiments. It is found that the fracture loads decrease with the number of drying–wetting and heating–cooling cycles. The crack-tip plastic zone is observed to expand over time, leading to a reduction in the fracture loading envelope. Furthermore, the fracture loading envelope generally decreases with increasing thermal treatment temperature, and the mixed-mode fracture resistance is the minimum in acidic environments. This paper provides a valuable reference for addressing the challenges of rock mixed-mode fracture under different environments.