Failure characteristics of shale after being subjected to high temperatures under uniaxial compression

Uniaxial compression tests and acoustic emission (AE) monitoring of shale specimens with horizontal and perpendicular bedding planes after being subjected to high temperatures were conducted to investigate the effect of a high-temperature environment on shale failure characteristics. The results reveal that specimens in the two bedding directions experienced severe rockburst failure. The rockburst processes of all the tested specimens were similar and can be divided into two main stages according to the specific failure characteristics, spalling stage, and ejection stage, and the increasing temperature had a significant effect on the rockburst characteristics of specimens in the two bedding directions at each stage. The fractal dimension of specimens in the two bedding directions increased with increasing temperature and increased much more for specimens with perpendicular bedding planes. The high-energy AE signals induced by the rockburst failure of specimens became more significant with increasing temperature, and the step-jump frequency of cumulative AE energy for specimens with perpendicular bedding planes increased gradually. The sudden drop in the amplitude of the AE b value resulting from spalling, ejection, and monolithic failure became larger for specimens in the two bedding directions with increasing temperature. Before the peak stress, the AE b value of specimens with horizontal bedding planes showed a stable period that was unaffected by increasing temperature, while the AE b value of specimens with perpendicular bedding planes also showed a plateau period in the prepeak stage when the temperature was lower than 100 °C and disappeared when the temperature exceeded 100 °C.