Abstract:Determining reasonable bedding drilling parameters is an important means to improve the efficiency of coal mine gas drainage.In the process of gas extraction, the matrix shrinkage and gas pressure changes caused by the deformation of the coal body are considered, and the COMSOL numerical simulation software was used. Two-hole and three-hole gas drainage effects under different drilling spacings, and gas drainage experiments were carried out in the 9306 roadway.The gas extraction effect under double hole arrangement shows two stages with the increase of drill hole spacing. The drill hole spacing is less than 3m, and the extraction time is short, and the extraction efficiency is high, but it decreases rapidly in the later stage. When the drill hole spacing is more than 3m, the extraction effect is lower than that of the drill hole spacing d=3m, and the gas extraction effect under three-hole arrangement is the best when the drill hole spacing d=3.5m.In addition, the area of the effective drainage area of each borehole is formulated. Through comparison, it is concluded that the gas drainage effect is the best when the three-hole arrangement and the spacing d=3.5m. The gas extraction test was carried out in 9306 roadway, and the difference between the test result and the simulated value was about 2.8%.The model has good applicability in the test mine, and can provide a certain theoretical basis for the design and optimization of drilling hole.
