Rock Hot - Force - Chemical (tmc), Coupled Fracture Toughness And Fracture Mechanism

Thermal-mechanical-chemical coupling fracture toughness and mechanics of brittle rock is studied theoretically and experimentally, which is significant not only for the development of rock fracture mechanics, but also for the calculation of fracture strength, assessment of safety and prediction of disaster in rock mass.Thermal-chemical coupling damage model and thermal damage model of brittle rock are proposed according to the chemical kinetics and consideration of effect of temperature on elastic modulus, repsectrively. Thermal-mechanical-chemical coupling damage model of brittle rock is established based on damage mechanics. By combining damage mechanics and fracture mechanics the formulae of thermal-mechanical-chemical coupling stress intensity factor is deduced in order to predict the critical stress intensity factor (i.e. fracture toughness) of brittle rock under thermal-mechanical-chemical coupling condition.Tensile (ModeⅠ), plane shearing (ModeⅡ) and anti-plane shearing (ModeⅢ) fracture toughness of brittle rock under thermal-mechanical-chemical coupling condition are determined by three-point bending, plane and anti-plane compression-shear tests. Test results show that ModeⅠ, ModeⅡand ModeⅢfracture toughness of brittle rock (KⅠC, KⅡC, KⅢC) are all decreased with the increase of temperature and concentration of the chemical solution. The tested values of fracture toughness are in good agreement with calculation values of fracture toughness, which verifies the validity of the formulae of thermal-mechanical-chemical coupling stress intensity factor.Thermal-mechanical-chemical coupling mechanism is studied by the chemical kinetics. The formula of thermal damage energy rate and chemical power are deduced and energy rate equation of thermal-mechanical-chemical coupling fracture of brittle rock is established based on the energy conservation principle, which provides the important basis for analyzing the crack propagation of brittle rock under thermal-mechanical-chemical coupling condition.