Research On Characteristics Of Structure Controlled Gas Occurrence And Prevention Technology In The Southeast Margin Of Linhuan Coalfield

The occurrence of gas and outburst in the southeast margin of Linhuan Coalfieldin Huaibei is dominated by the geological structure. Using the methods of theoreticalanalysis, numerical simulation, experimental analysis and engineering application,this paper gives a study on the gas occurrence state and gas occurrence law of Xutuanmine and Renlou mine, from the perspective of geochemistry, geotectonics, physicalchemistry, percolation mechanics, rock mechanics etc. A specialized gas control planfor different geological zones is drawn in the end. The results gotten in this study hasa vital meaning to the formulation of regional gas control plan under the situation ofsingle coal seam and coal seam group.Due to a Large area of thick redbeds lying on the south part of33District inXutuan mine, there is an obvious difference in gas occurrence between north andsouth. By taking samples through surface drilling, this paper contrasts the differencesin the mineral composition, pore structure, permeability and gas storage effect amongredbeds, mudstone, sandstone and siltstone. Combining the result of physicalparameters in red-cover coal seam and uncover ones above, it is found that the red bedhas not an obvious effect on the physical parameters of coal. The reason why thisdifference occurs is the storage effect of redbeds. The main pore system is dominatedby micropores and mespores, with a higher porosity and permeability than other kindsof samples, which lead to a worse storage effect on gas. The field experiments alsodemonstrate this phenomenon. The gas content of No.32seam with red bed coveringis not big as expected. A gas weathering area exists in coal seam. The results aboveillustrate that the permeability of coal seam with red bed is fair, a large amount of gasrun away through the coal seam below. That leads to a reduction in outburst risk.The Renlou mine is located in the front-end of the southern of Xusu arc nappestructure. The coal seam form in the permo-carboniferous system has gone through astrong geological transformation for twice or more, resulting ample of geologicalstructures. Based on the classification of the distribution characters of structures, thispaper measures the ground stress and gives a collection of gas emission statistics. Theresult reveals that the horizontal stress is2.46~2.72times as large as the vertical stress.Both the two directions of stress belong to pressure stress. These characters lead to theformation of deformed coal and provide a convenience for outburst. Besides, the gasemission in both sides of structure obeys a certain law. There are obvious relationships in the distance from largest gas emission point to the fault point with the fault throw,the abnormal gas emission scope also has such laws. These two parameters above is35times and60times as long as the fault throw respectively.According to the characters of gas occurrence control of structures, twocomprehensive gas prevention technologies for Xutuan mine and Renlou mine areestablished. A region and level based single coalseam gas prevention technology inXutuan Coal Mine and the protective seam mining and intensified pressure-relief gasextraction technology applies to the situation of Renlou Coal Mine.