Thermomechanical Time-Dependent Deformation and Fracturing of Brittle Rocks

A thermomechanical numerical model is proposed to describe the time-dependent brittle deformation of brittle rocks under different constant temperatures and confining pressures. The mesoscale model accounts for material heterogeneity and local material degradation, and the model introduces the concept of a mesoscopic renormalization to capture the cooperative interaction between microcracks in the transition from distributed to localized damage. The thermophysical parameters for the model were determined based on creep experiments of granite at temperatures of 23, 50, and 90°C. The numerical simulations agree well with the experimental data. We then explore the influence of temperature, differential stress, confining pressure, and sample homogeneity on brittle creep in granite using the same parameters. The simulated results show that the creep strain rate increases with an increase in temperature and differential stress and time to failure decreases, while creep strain rate decreases with an increase in confining pressure and sample homogeneity, and therefore time to failure increases. The proposed model is of great help to control and optimize rock engineering in granite.