Application of mine-hole joint microseismic technology in monitoring the damage depth of working face floor

Accurate prediction of the mining damage depth of floor is a key problem in the prevention and control of mining floor water hazard especially in the case with confined water. It is very important for developing the strategy of water control. According to the geological characteristics and working face layout of Baode coal mine, Shaanxi Province, a high-precision microseismic monitoring system consisting of well and hole arrays was deployed to detect the floor damage depth in working face 81307 in real time. The velocity model was calibrated and the location accuracy was verified by hammering method. It is proved that the location accuracy of microseismic monitoring system could meet the requirements of water prevention and control. During the monitoring period, the working face was mined 600 meters. The study results show that the damage depth of the floor is 30 meters below the floor, among them, the damage depth of 81308 No.2 air return laneway was deeper than that of 81307 No.1 air return laneway, but the damage depth of 81307 No.1 air return laneway was only 15 meters, which is consistent with the results measured by hydraulic fracturing experiment in the adjacent working face 81306. The combined mine-hole microseismic monitoring technology can obtain the damage depth and its spatial distribution characteristics of the floor of the working face, and it can better serve coal mine water prevention and control.