Abstract
In this paper, a weakly coupled thermo-mechanical model within the framework of ordinary state-based peridynamics is proposed to investigate thermal cracking behaviors of rocks subjected to heating from boreholes. The weakly coupled thermo-mechanical ordinary state-based peridynamic model is decomposed into two parts, i.e., thermal conduction and mechanical deformation. In the first part, temperature distributions in solids are analyzed based on the heat conduction equations. While, in the second part, thermally-induced deformation and fracture can be simulated by the mechanical computations. Moreover, a multi-rate explicit time integration scheme is proposed to model thermal cracking phenomena in rocks to overcome different time-scale problems in multi-physical systems. A benchmark example with analytical solutions is firstly modeled to validate the correctness and accuracy of the proposed numerical method, and numerical convergence studies of the weakly coupled thermo-mechanical ordinary state-based peridynamics are also conducted. The present numerical results are in good agreement with the analytical solutions and the previous experimental data. Then, three numerical examples are performed to investigate thermally-induced cracking behaviors, i.e. cracking patterns and temperature and stress evolutions. The proposed numerical method not only provides a new tool for coupled thermal-mechanical fracture problems in geothermal engineering, but also reveals the mechanism of thermal cracking phenomena in rocks.