MONITORING AND SIMULATION RESEARCH ON DEVELOPMENT OF WATER FLOWING FRACTURES FOR COAL MINING UNDER XIAOLANGDI RESERVOIR

There are over 80 million tons coal under the water body of Xiaolangdi Reservoir in Xin′an coal mine area,China′s Henan Province.The coal thickness changes from 0.0 m to 18.8 m;therefore,it is difficult to calculate exactly the height of water flowing fractured zone that may cause water disaster by using the known methods.In order to determine the upper limit of water flowing fractured zone,ultrasonic imaging technology is used in 5 ground surface boreholes;and the parallel network electrical CT technology is used in 5 boreholes in the coal mine to observe the failure process and the maximum height of water flowing fractured zone.Furthermore,physical and numerical simulations are also used to observe the height in more different excavating cases.The detecting and simulation results demonstrate that the height of water flowing fractured zone is mainly determined by coal thickness excavated in a nonlinear relationship.A formula is given based on this research;and it is used to determine the safe area while mining under the water body of Xiaolangdi Reservoir with combination of other affecting factors of water inrush.The result is verified to be reliable by successful industrial mining experiments of three working faces in the safe area.