Continuous-discontinuous element method for three-dimensional thermal cracking of rocks

Thermal cracking of rocks can significantly affect the durability of underground structures in engineering practices such as geothermal energy extraction, storage of nuclear waste and tunnelling in freeze–thaw cycle induced areas. It is a scenario of strong coupled thermomechanical process involving discontinuity behaviours of rocks. In this context, a numerical model was proposed to investigate the thermal cracking of rocks, in a framework of the continuous-discontinuous element method (CDEM) for efficiently capturing the initiation and propagation of multiple cracks. A simplex integration strategy was adopted to account for the influences of temperature-dependent material properties. Several benchmark tests were considered and the obtained results were compared with analytical solutions and numerical results from the literature. The results show that the fracture degree of the cases when considering temperature-dependent material parameters had 10% differences approximately compared with the cases with constant parameters.