Study on mine pressure law of compound roof working face with large dip angle under the influence of mining

Under the influence of mining, the overburden in the middle and upper part of the large dip compound roof working face is seriously damaged, causing the support not to be connected with the roof, which seriously affects the safety production. Aiming at this problem, this paper takes the 211112 large dip angle compound roof working face of Xinji No.2 Mine as the engineering background, and adopts the comprehensive research method of numerical simulation and field monitoring to study the mine pressure behavior law and roof control technology of 211112 large dip angle compound roof working face under the influence of mining. The results show that the height and width of the maximum overburden relief arch and the distance from the arch crown to the upper end of the working face under the condition of large dip compound roof are 5, 13 and 3 m higher than those under the condition of non-composite roof. After coal mining, the vertical stress of coal seam is asymmetrical in the inclined direction, and the maximum abutment pressure in front of the lower end of working face is about 32% higher than that in front of the upper end. The maximum vertical displacement subsidence of overburden of compoud roof is about 10% higher than that of non-compound roof working face. The pressure relief is faster and the damage degree of the middle and upper part of working face is more serious. The field monitoring shows that the force on the middle and upper part of the working face is larger, and the pressure comes first, which results in large subsidence displacement and high pressure relief degree of the middle and upper part of the working face, which is consistent with the simulation results. It explained that the scope of No.72—No.95 supports (middle and upper parts of the working face) in 211112 working face had roof leakage, and the supports were not connected to the roof. On this basis, the control technology of filling broken composite roof with inorganic grouting reinforcement material is proposed. The field trial results are good, and the safe and efficient mining of the large dip Angle composite roof working face is realized.