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Abstract To study the effect and range of pressure releasing protection of overlapping mining of the upper protective layer in close distance prominent coal seam group, Chiyu Mine was taken as an example in this paper and FLAC3D was used to establish the overlapping mining model of the upper protective layer to study the protective effect and range of the protected No.4 coal seam after the overlapping mining of the No.2 and No.3 coal seams, which were used as the upper protective layer. The results showed that after the mining of the first upper protective layer No.2 coal seam, the strike and propensity unloading rate of the No.4 coal seam reached 37% and 32% respectively, and the maximum expansion and deformation rate reached 3.3‰ and 3.8‰ respectively. After the overlapping mining of the No.3 coal seam of the second upper protective layer, the strike and propensity unloading rate of the No.4 coal seam reached 44% and 36% respectively, and the maximum expansion and deformation rate was about 4.8‰ and 5.3‰ respectively, and the pressure releasing rate and expansion and deformation rate were continue to increase, which played an obvious role in secondary protection of pressure releasing. According to the on-site measurement, after the overlapping mining of the upper protective layer, the residual gas outflow from the protected layer was less than 8m3/min, which was in line with the relevant regulations on gas extraction rate, and the goal of safe and efficient mining of the close-range coal seam group was realized. The reference for mining of similar close distance prominent coal seam group could be provided by the study results.
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