A non-Fourier law-based peridynamic thermo-mechanical coupling model and simulation of thermal damage and fracture in granite

It is of great significance to study the thermal damage and fracture characteristics of rocks for deep rock engineering projects, such as geothermal exploitation. Within the framework of the traditional classical ordinary state-based peridynamic theory, a thermo-mechanical coupling model based on a non-Fourier heat conduction law was proposed by introducing a dual-phase-lag model. The model was validated through transient heat conduction problems in a plate and thermal damage and fracture tests on LdB granite. It is found that the simulation results accurately reflect the thermal damage and fracture characteristics, as well as the discontinuity in temperature distribution, of LdB granite. Furthermore, through numerical analysis, it is observed that the temperature gradient relaxation time promotes heat conduction, leading to an increase in the degree of thermal damage and fracture with an increase in temperature gradient relaxation time, while it decreases with an increase in heat flux relaxation time. This research provides valuable insights for a better understanding of the thermal damage and fracture behavior of rocks and offers beneficial explorations for optimizing deep hot dry rock geothermal energy extraction engineering.