Phase-Field Modeling of Thermal Fracture and Shear Heating in Rocks with Degraded Thermal Conductivity Across Crack

By incorporating two different fracture mechanisms and salient unilateral effects in rock materials, we propose a thermomechanical phase-field model to capture thermally induced fracture and shear heating in the process of rock failure. The heat conduction equation is derived, from which the plastic dissipation is treated as a heat source. We then ascertain the effect of the non-associated plastic flow on frictional dissipation and show how it improves the predictive capability of the proposed model. Taking advantage of the multiscale analysis, we propose a phase-field-dependent thermal conductivity with considering the unilateral effect of fracture. After proposing a robust algorithm for solving involved three-field coupling and damage-plasticity coupling problems, we present three numerical examples to illustrate the abilities of our proposed model in capturing various thermo-mechanically coupled behaviors.