Study on surrounding rock stress evolution law of fully-mechanized top coal caving mining face under role of overlapping coal pillars

According to the high mine strata behavior phenomenon occurred when a coal miming face in a Carboniferous ultra thick seam passed through the Juras sic coal pillar in the top seam, a numerical simulation and site measuring method were applied to the study on the stress evolution law of the surrounding rock under th e role of the overlapping coal pillars and the mining coupling. The UDEC numerical calculation software was applied to the simulation on the mining process of the coal mining face under the role of the overlapping coal pillars. The results showed that when the coal mining face mined at the relevant area of the Jurassic coal pillars, the advance support pressure peak of the coal mining face was ranging from 32 ~ 37 MPa and was improved by 25% ~ 33% higher than the non coal pillar area. The lateral support pressure of the coal mining face and the coal pillar stress at the Jurassic minefield boundary were overlapped, the lateral support pressure influence scope of t he coal mining face was about 120 m and the surrounding rock stress of No.5105 gateway reached at27 ~ 32 MPa. A rock burst occurred in the abandoned roadway wa s a result of the coupling role with the advance support pressure and overlapping coal pillar stress transmission. A roof dynamic monitoring and measuring system was applied to the real-time monitoring and measuring of the powered support working resistances. The analysis showed that when the coal mining face pushed to the relev ant area of the Jurassic goaf, the powered support working resistance would be higher during the roof strata weighting period, the resistance of the powered support WO uld be frequently increased and the mine strata behavior would be serious.