Abstract:To investigate the influence of loading rate and high temperature on the dynamic fracture toughness of rock, dynamic fracture tests were carried out on notched semi-circular bend specimens under four temperature conditions based on the split Hopkinson pressure bar system. Experimental and analytical methods were applied to investigating the effect of temperature gradient on the stress waves. A high-speed camera was used to check the fracture characteristics of the specimens. The results demonstrate that the temperature gradient on the bars will not significantly distort the shape of the stress wave. The dynamic force balance is achieved even when the specimens are at a temperature of 400 °C. The dynamic fracture toughness linearly develops with the increase of loading rate within the temperature range of 25-400 °C, and high temperature has a strengthening effect on the dynamic fracture toughness.

Key words: ambient high-temperature condition; dynamic fracture toughness; notched semi-circular bend specimen; split Hopkinson pressure bar; Fujian granite