Optimization designing method of pressure-relief gas drainage in adjacent layers based on key strata movement

The reasonable layout of gas drainage roadway (borehole) is the basic prerequisite to realize precise drainage of pressure-relief gas in adjacent strata. Based on the in-depth analysis of control mechanism of movement of overburden key strata on pressure relief and migration of adjacent strata, a new Optimization designing method of pressure-relief gas drainage in adjacent layers based on key strata movement was proposed. The results show that the reasonable layout of pressure-relief gas drainage roadway (borehole) in adjacent strata is the spatial range between the boundary of collapse zone and gas-conducting fracture zone, and the maximum development height of the gas-conducting fracture zone boundary from coal bed roof can be determined by the method to predict height of fractured water-conducting zone by location of key strata. The reasonable layer position of the adjacent pressure-relief gas drainage roadway (borehole) is the middle of “O” shaped fissure zone. The width of “O” shaped fissure zone can be predicted according to the functional relationship with the mining height, the overlying key stratum structure, and the mining depth. This method has been applied and verified in practice of adjacent pressure-relief gas in adjacent layers in Yangquan mining area,and its adjacent layer pressure-relief gas drainage rate can reach to 92%, which can better guide the practice of coal and gas co-mining under the coal seam group mining conditions.