Thermomechanical Behavior and Mesoscale Simulation of Conglomerate under Impact Loading for Geothermal Engineering

To investigate the mechanical response of conglomerate under coupled high-temperature and dynamic loading conditions, impact compression tests were conducted using a ⌀50 mm Split Hopkinson Pressure Bar (SHPB) system at temperatures of 25 °C, 100 °C, 150 °C, 200 °C, 250 °C, and 300 °C. At lower temperatures, the specimens exhibit greater energy absorption and dissipation capacity, which promotes crack propagation and energy release. In contrast, at elevated temperatures, energy reflection becomes more pronounced while dissipation decreases, leading to a more brittle failure mode. Mesoscopic analysis based on finite element simulations further clarifies the influence of temperature on stress distribution and crack evolution during impact failure. The results indicate that the dynamic compressive strength of conglomerate decreases with increasing temperature, with the peak stress dropping from 192 MPa at 25 °C to 116 MPa at 300 °C, corresponding to a reduction of approximately 39.5%. Fractal dimension analysis reveals a positive correlation between fragmentation degree and temperature, with significantly finer fragments observed at 300 °C compared to 25 °C. These findings provide theoretical insights and practical guidance for evaluating the stability of high-temperature conglomerate formations and optimizing rock-breaking parameters in geothermal engineering.