Combined effects of temperature and axial pressure on dynamic mechanical properties of granite

In order to get the dynamic mechanical properties of deep rock mass suffered both high temperature and high pressure, impact loading experiments on granite subjected to temperature and axial pressure were carried out. Furthermore, the internal structure characteristics of granite under different temperatures were observed by scanning electron microscopy (SEM). The results show that the longitudinal wave velocity assumes a downward trend which shows a rapid drop before falling slowly as the temperature increases. The uniaxial compressive strength of the specimen decreases significantly at temperatures of 25-100 degrees C compared to that at temperatures of 100-300 degrees C. The peak strain rises rapidly before the dividing point of 100 degrees C, but increases slowly after the dividing point. The internal structure of the rock changes substantially as the temperature increases, such as the extension and transfixion of primary and newborn cracks. In addition, the thermal damage under axial pressure is greater than that described by the longitudinal wave velocity and the phenomenon shows obviously when the temperature increases.