Dynamic Mechanical Behavior of Granite under the Effects of Strain Rate and Temperature

The dynamic properties of rock under different strain rates and temperatures play an important role in the stability of rock mass. To investigate the dynamic behavior of granite specimens subjected to high strain rates and relatively low temperatures, dynamic compression tests were carried out using the split Hopkinson pressure bar (SHPB) experimental system. The strain rate effect on dynamic characteristics of granite at temperatures from 25°C to 150°C were studied and the relationships between dynamic failure modes and the energy absorption of granite specimens at different strain rates were revealed through rock fragment analysis. Meanwhile, the damage evolution was quantified by elastic moduli and porosity. The results indicate that the dynamic peak stress, peak strain, and specific energy absorption (SEA) have positive correlations with strain rates. The dynamic compression strength shows an increase when the temperature rises from 50°C to 110°C, then decreases with higher temperatures, while the elastic modulus is more sensitive to temperature than strain rate. The thermal damage decreases at low temperature and appears to be negative below 110°C. A power function relation between SEA and fragment size is found to exist at different strain rates. It denotes that 110°C is a critical temperature that induces changes in physico-mechanical properties and the relatively low temperature has an enhancement effect on the dynamic strength of granite samples.