Study on pressure relief effect of repeated mining in cross-stacked protective face

Abstract

In order to study the pressure relief effect of repeated mining on the cross-stacked protective layer working face, a FLAC3D numerical model was established by taking 15303 and 8123 cross-stacked protective layer working face in Lunan sub-district of Xinjing Mine as the object. The evolution law of plastic zone, in-situ stress and expansion deformation of 3# protected coal seam under the mining condition of 8# single protective layer and the mining condition of 8# and 15# coal seam overlapping protective layer is simulated, and the field test is carried out. The results showed that after the cross-stacked working face mining, the stress state of the protected layer presents a non-uniform distribution state, which can be divided into five areas on the plane, respectively: sufficient pressure relief area, insufficient pressure relief area, weak stress concentration area, strong stress concentration area and original rock stress area; the stress concentration of the protected layer decreases in the overlapping area of the two working faces, while the pressure relief degree increases in the pressure relief area; the stress concentration of the protected layer increases greatly in the four intersection areas where the two working faces cross vertically; the pressure relief effect of cross-stacked working face is obviously better than that of single protective layer mining.

Keywords

• protective coal seam mining
• cross-stacked protective workface
• pressure relief effect
• detailed characterization
• pressure relief scope