Influence of temperature on the strainburst characteristics of granite under true triaxial loading conditions

The experimental study of the strainburst on granite treated with different high temperatures was conducted using a novel true-triaxial rockburst test system. During the test process, a loading path was given by keeping one free face and then loading on other five faces. The strainburst process, the failure patterns, the peak stress, the acoustic emission (AE) signal characteristics, the fragment characteristics and the kinetic energy of the ejected fragments were analyzed by employing the stress-strain curves, the high speed camera system and the AE technology. The experimental results show that temperature has significant influences on the strainburst. The critical temperature of these specimens is 300 °C. With the temperature increasing from 30 °C to 300 °C, the peak stress, the peak strain and the AE process exhibit a slight variation, while the kinetic energy of the ejected fragments rapidly increases. When the temperature increases from 300 °C to 700 °C, the peak stress and the kinetic energy apparently decrease, but the peak strain swiftly rises. The time of the AE quiet period and the fragmentation increase with rising temperature. Compared with the specimens at 30 °C, the specimens treated with temperatures from 100 °C to 500 °C have more intense rockburst, while the specimens treated with temperatures from 600 °C to 700 °C have a lesser kinetic energy of the ejected fragments.