Pioneering insights into High-Temperature sandstone fracture Mechanics: Integrating damage evolution modeling with experimental validation

To address the high-temperature-induced damage and fracture phenomena in deep underground rock masses, this paper conducts fracture toughness tests on thermally damaged sandstone, meticulously monitoring crack morphology, surface displacement, and strain fields during the experiment. A damage evolution-focused thermo-mechanical coupling model is employed for simulations to examine the thermal damage and failure processes of sandstone under varying temperature conditions. The analytical solutions of the model are validated against experimental results, leading to the following conclusions: thermal damage in rocks is predominantly tensile, and as the temperature increases, the tensile damage intensifies. The fracture toughness K_IC of sandstone decreases with increasing temperature but increases to varying degrees as the prefabricated crack length decreases. As the temperature rises, the ductility of the rock improves, its deformation capacity increases, and the material gradually becomes more heterogeneous. The consistency between laboratory results and numerical simulations further demonstrates the rationality and applicability of the proposed damage evolution-focused thermo-mechanical coupling model.