Loose Aquifer Thickness Thin Bedrock Mining Strata Movement And Mining Parameters

This paper, according to the specific geological conditions of Huainan Gubei Coal Mine, in view of the thin bedrock in mining abutment pressure of coal seam and aquifer strata rock mass under the action of water pressure, with the comprehensive research methods of the combination with analog simulation and numerical simulation, and through the site measurement, analyzed the stope appeared rock pressure and strata movement rule. Research results show that:1. During working face advancing, the loose aquifer compressed、settled and bended、subsided、deformed, which resulted in coal face periodic cyclical size-small periodic weighting interval and large periodic weighting interval. The roof pressure along the direction of working face advancing changed in a periodic vein, that is, the distribution of three-dimensional contours of the roof pressure are "vein mountains" characteristics. In working face, during large periodic "mountains", area is larger, peak is higher and continuous length is longer.2. The existence of the dynamic stress of the arch coal seam surrounding rock, which is the main supporting body stope. The roof stress distribution law is basically the same at same height. The vertical stress of coal seam roof is reducing gradually with the increase of roof height, stress curve from "U" shape form gradually to "V" shape form. The vertical stress of the coal wall in front of the peak is gradually increasing with the increase of mining width or mining height.3. Vertical displacement along the roof of coal seam is divided into initial stage, active stage, severe stage and stable stage; Along with the advance of working face, the movement of the strata is mainly to the vertical displacement of the mined-out area, which is "V" shape. Three stages of strata displacement in turn is increase, decrease, steady. With the increase of the roof height, displacement is gradually decreasing, peak position is different, the displacement curve turns to flatten. Displacement change laws of roof, at the same height, is basically same. With the increase of mining height or width, roof displacement increase accordingly at the same height.4. In the process of caving mining method, the damage height of overburden rock increases gradually with advancing distance. When there is large cycle to pressure, failure pattern is obvious "arch". As for filling mining method, in working face advancing to40m, the damage height of overburden rock is stable to8.9m, and during the entire process of stoping, there is no big phenomenon of periodic pressure but irregular failure pattern. Because filling the mined-out area was filled with filling body, it reduced the free rotation of space below the strata, played a very good supporting role to above rocks, the mine pressure seemed relatively moderate.This paper aimed at thin bedrock under the unconsolidated aquifer appear stope pressure rule and law of strata movement were studied. The results of the study provide Huainan mining area under loose aquifer water threat safety mining of coal seam with thin bedrock with certain reference value.