Energy dissipation characteristics of high-temperature granites after water-cooling under different impact loadings

Studying the energy dissipation characteristics of high-temperature rock after cooling with water during geothermal drilling construction is crucial to improving rock crushing efficiency. The energy dissipation characteristics of granite were investigated by conducting dynamic tests with a split Hopkinson pressure bar (SHPB) system under different impact loadings. The granite specimens were subjected to temperatures from 25 degrees C to 1000 degrees C. The micromorphology and pore distribution of granite were obtained by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests. The porosity change trend could be divided into two stages at 400 degrees. The micropores and small pores accounted for over 75.0% before 400 degrees C The medium pore proportion increased rapidly when T >= 400 degrees C. In addition, the dynamic peak stress and peak strain increased with incident energy, while the trend of the change in the dynamic elastic modulus was not apparent. The proportion of dissipated energy showed an upwards trend when the heating temperature varied from 25 degrees C to 800 degrees C, while the absorbed energy of granite heated to 1000 degrees C decreased. The energy utilization efficiency was the highest when the strain rate was between 100 s(-1) and 120 s(-1).