Study On Ground Pressure Behavior Of An Long Mining Face With Thick Bedrock Shallow Seam And Large Mining Height

With the development of Shengdong coal area, the shallow seam with thin bed rock is deeply studied by researchers in our country. The overburden movement and mining pressure behavior of typical shallow coal seam mining face is obtained, which can well guide the field production. Recently, with the extension of the mining face, the mining height and the height of the bed rock of the overburden in Shengdong coal area, the study of the overburden movement and mining pressure behavior of shallow coal seam with thick bed rock becomes the new problem.Based on the geological conditions of the 61203 mining face of Wulanmulun Coal Mine, the mining pressure behavior of the shallow coal seam extended mining face with thick bed rock and high mining height is studied by means of theoretical analysis, similar simulation experiment, numerical simulation and field monitoring data analysis. The overburden movement is studied and calculated theoretically by"key strata theory". The support working resistance, overburden movement and floor support pressure are analyzed by similar simulation experiment. The advancing process of mining face with high mining height and thick bed rock is simulated with RFPA2D numerical simulation method, and the roof caving process and overburden movement is analyzed. With the field monitoring, the mining pressure is analyzed in the strike direction and trend direction, the length of the face and the suitable support working resistance under thick bed rock conditions are studied.The study shows that, the mining pressure behavior of the extended mining face with high mining height in the 1-2 coal seam of Wulanmulun Coal Mine is remarkable. The support resistance is relatively large when weighting, and the mining face pressure is big in the middle and small in two sides; The first weighting step distance is 42～64m, the average periodic weighting step distance is 12.9～13.3m; The weighting of the mining face changes periodically and heterogenely, and the suitable working resistance range is 9827～13115kN per shelf. The"support-surrounding rock"interrelationship is simulated, and the floor support pressure influence area is obtained. The overburden will not crack fail along mining face, but appears"three-zone"distribution. The mechanical model of the key block is built with"key strata theory", and the theoretical calculated result of suitable support resistance of the mining face with thick bed rock and thick key strata conditions is obtained.