Mechanical property variation mechanisms of granite subjected to real‐time high temperatures and subsequent cooling treatment

Abstract During geothermal resource exploitation, the potential deterioration of mechanical properties in high‐temperature granite subjected to cooling poses a significant safety concern. To address this, the present study investigates the coupled thermo‐mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis. Initial investigations involve X‐ray diffraction, thermal expansion test, thermogravimetric analysis, and uniaxial compression test. Results show the significant variations of granite properties under different thermal conditions, attributed to temperature gradients, water evaporation, and mineral phase transitions. Subsequently, a model considering temperature‐dependent parameters and real‐time cooling rates was employed to simulate linear heating and nonlinear cooling processes. Simulation results indicate that the thermal cracking predominantly occurs during the heating stage, with tensile failure as the primary mode. Additionally, a faster real‐time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite. This study effectively elucidates the thermo‐mechanical coupling behavior of granite during heating and cooling processes, providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.