Research On Pressure Law Of Working Face In Close Coal Seam Mining Under Goaf

In order to solve the serious roadway deformation with fully mechanized caving face in close coal seam mining under goaf, taking Shanyin County Nanyangpo mine as engineering background, it is studied that lateral stress of working face two lane and roadway support design by applying the integrated research method of combining theoretical analysis, numerical simulation and engineering practice.Stratum quality index was used to evaluate integrity and hard degree of roof strata, and gob in fully mechanized sublevel caving mining was eventually filled by immediate roof; Based on traditional ground pressure theory, the immediate roof caving height, main roof thickness and pressure equivalent were calculated; According to grade index of main roof, it was determined to be grade I, and pressure behavior is not obvious; Roadway surrounding rock was classified by structural stability index,4105transport lane was influenced by the structure and mining, and it belongs to mid-stable.Obtained from results of FLAC3D numerical simulation,4105transporting lane deformation was caused by unreasonable section coal pillar size and high stress of upper coal seam. Lateral pressure influence was effectively decreased under the condition of changing section coal pillar from46m to38m, considering structure influence, the lower coal mining working face should lag120m.Combined with overlying strata laws,"top coal+immediate roof+collapse strata"structure model was established, and reasonable working resistance of support was calculated to be not less than9690KN. In normal pressure, the selected hydraulic support in fully mechanized sublevel caving face mining was enough to ensure the safety of stope. For improving the serious deformation problems of roadway, supporting design was divided into respectively on stability and non stability of surrounding rock; Field observations show that the optimized design of roadway can meet field requirements with surrounding rock deformation reducing, and the anchor can reach reasonable value.