Mechanical Behavior and Damage Constitutive Model of Granite Under Coupling of Temperature and Dynamic Loading

Dynamic compression tests of Huashan granite were conducted using an improved split-Hopkinson pressure bar. The effects of the treatment temperature and strain rate on the mechanical behaviors (for example, the stress-strain curve, dynamic strength, elastic modulus, energy absorption, and failure mode) of the granite samples were explored. In addition, a statistical damage constitutive model for the rock was developed based on a Weibull distribution, and the influencing factors of the model parameters were analyzed. The results show that the enhancement effect of the strain rate on dynamic compressive strength under high temperatures still exists. However, the strain rate has no significant effect on the elastic modulus. The influences of the treatment temperature on the dynamic strength and elastic modulus are complex. There is a positive linear correlation between the energy absorbed by the sample and the incident energy. As the strain rate or incident energy increases, the failure modes of heat-treated samples change from axial splitting to pulverization. Under the same dynamic loading, an increase in the temperature can exacerbate the fragmentation degree of the sample. The proposed statistical damage constitutive model can accurately describe the effects of the treatment temperature and strain rate on the stress-strain responses of rock, and its parameters have definite physical meanings. Thus, the model is a very good tool for the analysis of thermo-mechanical coupling problems involved in deep rock mass engineering.