Modification of the rock burst criteria based on the strain rate function under large-scale strain rates

The strain rate is a crucial parameter for distinguishing dynamic and static loading. However, further research is needed to fully understand coal's mechanical behavior across large-scale strain rates. This paper primarily utilizes laboratory experiments to examine the strain rate effect of coal under large-scale strain rates, focusing on the strength of coal. The theoretical criterion for rock bursts under large-scale strain rates was refined using the critical stress criterion for rock bursts. The main findings are as follows. The variation in peak stress can be characterized by two distinct stages: a linear slow growth stage followed by an exponential rapid growth stage, observed under low, medium, and high strain rates (10−5 to 104 s−1). Additionally, the burst tendency index decreases as the strain rate rises, with lower strain rates promoting greater accumulation of strain energy. When the critical stress level exceeds the peak stress of coal, the likelihood of rock bursts rises considerably. Consequently, significant changes in the critical stress value, induced by external disturbances, can serve as a precursor indicator for rock bursts. The updated rock burst criteria, considering various loading disturbances, establish a theoretical basis for preventing rock bursts under different strain rate conditions.