Theory Of Coal And Gas Outburst Prevention During Mining And Key Technology Research In Upper Cover Of Hongling Coal Mine

For the coal and gas outburst coal seam, caving protective coal seam is one of the mosteffective methods. Hong Ling coal mine, which belong to Shenyang coal trade group, is theresearch background of this article, and the11#very thin coal seam is selected as the protectivecoal seam because of the occurrence of coal seam and gas casualty.The occurrence of coal seam and gas outburst casualty of Hong Ling coal mine are firstlyanalyzed. On this background, rock mechanics, elastic mechanics and theory of rock masspressure relief are synthetically used to establish the pressure relief mechanical model of gobfloor rock mass, then the permeability after protective coal seam caving of the rock mass isanalyzed. The mining fracture evolution in adjacent rock of the gob is studied by the similarityexperiment in laboratory and digital speckle observation technology. FLAC3D numericalsoftware is used to simulate the pressure relief range under mining after protective coal seamcaving. Based on these conclusions, the field experiment is processed. First of all, the cavingscheme of very thin11#coal seam and the gas extracting methods of the protective coal seam isdesigned, then the effectiveness of gas extracting from12#coal seam and parameters variation istested and analyzed. After that, the erasing coal and gas outburst authentication of12#coal seamis processed.The residual gas checking method of the protected coal seam is established in the article.The residual gas parameters of the protected coal seam is checked by testing parameters fromchecking borehole which drilled from bottom tunnel to protected coal seam. The field testingdata shows that the dilatancy of the protected coal seam is7.2‰after stable deformation;the air permeability coefficient is1010times larger than that original situation aftercaving protective coal seam and processing intensified extracting methods of protectedcoal seam. The gas extracting ratio of the protected coal seam in protective range is77.5%, and the gas pressure of the protected coal seam decreases from7MPa to0.35MPa. The protected coal seam gas content decreases from22.5m3/t to5.06m3/t.Safety and effective caving manner of the protective and protected coal seam is realized.