Permeability distribution law of protected coal seam in mining-affected zone

In order to better conduct the gas drainage in a mining-affected zone, a working face and its protected coal seam of a mine in Huainan mining area were used as the research object. Physical similarity simulation, FLAC3D numerical simulation, historical fitting have been used to discuss the variation of the permeability of the protected coal seam on the target working face. The results show that for the protected coal seam in strike section, the length of the pressure relief area in the front of the working face is about 20 m, and the length of the pressure relief area in the back of the working face is about 30 m, the length of the fracture zone is about 30 m, and the rest is the re-compaction area. The permeability in pressure relief area is 150×10-3 μm² to 250×10-3 μm², the permeability of the fracture zone area is 400×10-3 μm² to 800×10-3 μm², and the permeability of re-compaction area is 16×10-3 μm² to 100×10^-3 μm². The permeability of the protected coal seam in the mining area increased by 32~1 600 times compared with the original permeability.