A Two-phase Model of Air Shock Wave Induced by Rock-fall in Closed Goaf

In this paper, a two-phase model of air shock wave induced by rock-fall in closed goaf was proposed. The model was made up of the uniform motion phase (velocity was close to 0 m•s-1) and the acceleration movement phase. The uniform motion phase was determined by experience and the acceleration movement phase was derived by the theoretical analysis. After this, a series of experiments were performed to verify the two-phase model and obtained the law of the uniform motion phase. By observing, the acceleration movement phase was taking a larger portion and the uniform motion phase was smaller when height of rock-fall was higher. By comparison, experimental results of different falling heights showed good agreements with theoretical analysis, which verifies the effectiveness of the two-phase model. Finally, the model was tested with computational fluid dynamics (CFD) numerical simulation by three groups of different falling height. The two-phase model could provide a reference and basis for estimating the air shock waves' velocity and design the protective measures.