Theoretical study on the pressure relief range of the upper protected coal seam in protective layer mining

The mining of protective layers is recognized as an economical and effective measure for pressure relief, anti-erosion and prevention of coal and gas outbursts. To explore the influence law of protective layer mining on the pressure relief range of the protected coal seam, this paper takes the No. 6 Mine of Pingdingshan Tian’an Coal Industry Co., Ltd. as an example. Through theoretical analysis, the theoretical pressure relief protection range of the upper protected layer caused by the mining of the protective layer of the coal seam is studied, and the theoretical pressure relief angle along the tendency, the theoretical pressure relief angle along the strike and the theoretical pressure relief range along the vertical direction are determined. The results show that: (1) The factors influencing the protective effect during the mining of the protective layer include the properties of the rocks between layers, the duration of the protective effect, and the relative interlayer distance. (2) When the lower protection range of the protected layer is 76.32 m away from the inner roadway of the Wu9−10-32020 machine, the inner offset distance is 16.23 m. The upper protection range is offset from the wind tunnel of Wu9−10-32020. When the layer spacing is 76.32 m, the offset distance is 10.73 m. (3) The protection range of the protected layer is offset from the cut eye and the stop-sampling line of Wu9−10-32020. When the layer spacing is 76.32 m, the offset distance is 44.07 m. (4) The maximum distance between the protective layer Wu9−10 coal seam and the protected layer Ding5−6 coal seam is 73.62 m < 100 m < 122 m, which is within the effective pressure relief range. It not only meets the pressure relief requirements for mining the protective layer but also cannot damage the mining conditions of the protected layer.