| Due to the wide range of overburden failure after the working face of thick coal seam is mined,the successive breakages of the basic roof and the overlying key strata often affect the appearance of the working face with combined action.In particular,the sudden breaking of the hard and thick rock strata in overburden will cause the rock strata controlled by it to sink simultaneously,and the load will be transferred to the working face layer by layer in the rock strata,thus leading to or inducing the stope mining pressure disaster,such as the crushing frame the dynamic load mining pressure,and the coal body rushing out.In the mining process of the fully mechanized caving face 42107 in Buertai coal mine,the mining pressure is extremely strong,which is mainly manifested by the characteristics such as high compressive strength,high dynamic load coefficient of the support and large shrinkage under the movable column of the support,etc.,and the support compression phenomenon occurs many times in the working face,and the roof control is difficult,which poses challenges to the safe and efficient production of the working face.Paper integrated the in-situ measurement,physical similar material simulation and numerical simulation and theoretical analysis of research methods such as system characteristics of 42107 fully mechanized face press,the far field key strata occurrence situation,the up and down after the mining of coal seam mining the cumulative development of fractured zone height,based on the 42107 fully mechanized face strong pressure mechanism of a preliminary study,to explore how to effectively relieve pressure strength,the main research results are as follows:(1)Through the field measurement and analysis of the support resistance of the working face,it is found that the working face 42107 has a period of pressure,with a small period of 10.2m~30.7m and an average of 18.6m.The pressure step distance in large period is 57.5m~83.6m,with an average of 67.85 m.The average step distance of strong ore pressure development is 141.6m,and the average duration is 31.6m.(2)By comparing the theoretical calculation and numerical simulation results,the cumulative development height of the “two zones” in repeated mining is determined comprehensively.After mining of 2-2 coal seams,the key strata in the far field are not broken,while after mining of 4-2 coal seams,the key strata in the far field will be broken successively.The development range of mining-induced fractures in 2-2 coal seam and 4-2 coal seam is further simulated by two-dimensional physical simulation experiment,which directly reflects the movement of overlying strata.Combined with the occurrence of key strata in overlying strata identified,it can be concluded that the fracture movement of key strata in the far field may be the main reason affecting the strong ore pressure in the stope.(3)According to the mechanism of strong mining pressure development on the working face,this paper puts forward some measures to control the roof,such as weakening and modified roof control technology for roof crack caused by water pressure,local top coal remaining on the working face,etc.,so as to reduce the mining pressure development intensity and effectively guide the safe production on the working face. |
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