Energy sources of rock burst and the influence of the surrounding rock mass

The kinetic energy for rock ejection in a rock burst event is converted from the strain energy stored in the burst rock, a portion of strain energy released from the surrounding rock mass and a portion of seismic energy transferred from fault-slip seismicity. The kinetic energy is mainly contributed by the burst rock itself in a small-scale strain burst, but the energy released from the surrounding rock mass plays a major role in a large-scale rock burst. Intergranular and extensional cracking is dominating in burst-prone rocks, while in the non-burst-prone rocks the dominating cracking is intragranular and shear. Both the crack density and the average opening width of cracks are very small in burst-prone rocks.