Study On The Strata Behavior Characteristics Of Fully Mechanized Caving Under The Goaf Of Contiguous Seam Group

The goaf and residual coal pillars of the upper mined seam lead to a significant change for roof structure and stress of the lower seam to be mined by schedule.Therefore,overlying strata movement and strata behavior of the lower seams mining have its particularity compared to single coal seam.In Liujia coal mine,there exists closed distance seam group including 9 mineable coal seams,Fully mechanized carving panel S ? N26-7,with average coal thickness of 6.91 m and complex coal seam structure,is being mined nowadays.It is separated with the upper 6-6 seam merely by a mud stone of 2 m.During the mining,the deformation of ventilation roadway beside goaf and coal pillar is quite severe.In the paper,the overlying strata movement,surface movement and strata behavior characteristics were studied,which have provided scientific basis for arrangement of mining sequence,mining method and optimization of panel and have a guideline for roadway supporting technology,mining area layout and safety production.Through the theoretical analysis,detection of EH-4,the paper confirmed the height of the "Three Zone" of overburden after the S ? N26-7 fully mechanized top-coal caving panel mined;It has set up the calculation model of supports load which based on the structure "Immediate Roof Strata +Caving Zone Strata+ Fractured Zone Strata",and the rationality of support's selection has been verified;It has also predicted the deformation characteristics of S ? N26-7 fully mechanized top-coal caving panel overburden by using the Mining Subsidence Disaster's Prediction and Forecast System,obtained the temporal and spatial pattern of motion of the overburden and surface.The conclusion of abutment pressure and weighting interval in the S ? N26-7 fully mechanized top-coal caving panel decreased because the mining of 6-6 coal seam was achieved by simulating the mining process of 6-6 and 6-7coal seam,using FLAC3D and UDEC numerical simulation software.Through the detection in S ?N26-7 fully mechanized top-coal caving panel,showed that setting load of hydraulic support in S ?N26-6?7 fully mechanized top-coal caving panel was low,so it should be increased.From monitoring results of mining roadway,the scope of lead abutment pressure is 35m.Finally,we optimized the length,width of panel,hydraulic support's selection,roadway support,section coal pillar in S ? N26-7 fully mechanized top-coal caving panel based on research results of overburden stratum movement and disturbance stress.The research of the structure of overlying strata movement characteristics of Liujia Coal Mine S?N26-7 full mechanized caving mining and the stress distribution and evolution law of stope,we determined the characteristics of close distance coal seam repeated mining panel,the upper coal seam mining makes the pressure under the mining panel more moderate,The results of the study provide guidance for the safety and high efficiency mining of Liujia Coal Mine.The study on the law of mining pressure in fully mechanized caving panel under the condition of close distance coal seam mining provides theoretical guidance and technical reference for the production of coal mine under similar conditions.