Study On Movement Laws Of Hard Roof And Control Technology Of Thick Coal Seam With Large Mining Height

Because of the hydraulic support crushed and rib spall problems under the condition of thick coal seam with large mining height, in response to these circumstances, this thesis is based on the research background of fully mechanized working face with large mining height in 402 panel in Jinhuagong Coal Mine of Datong mining area, using theoretical analysis, numerical simulation and field measurement methods, analysis of movement laws of roof and characteristics of stress field distribution in thick coal seam with large mining height.(1)Study on the movement laws of roof and characteristics of stress field distribution of thick coal seam with large mining height by using numerical simulation method, according to 8210 working face’s geological conditions in Jinhuagong Coal Mine. From the simulation results can be known that different cutting height affect the overlying strata ’s broken forms, the greater cutting height the more likely sliding instability of key stratum, and larger subsidence of the overlying strata. Key stratum’s different broken forms, have an impact on stress field distribution characteristics, when broken key strata forms masonry structure, the abutment pressure peaks advanced coal wall is greater than that when broken key strata does not form masonry structure, the distance between peaks and coal wall is less than that when broken key strata does not form masonry structure, The height of stress arching by key stratum is proportional to cutting height.(2)Building the mechanical model of the relationship between supports and surrounding rock in fully mechanized working face with large mining height with key block breaking angle variables. The key block sliding instability conditions are analyzed, the smaller α is the greater possibility of key blocks sliding instability when the other conditions are determined, get the support needed support resistance are not less than 12.65 MN per frame. Also studied the rib spall by numerical simulation method, the range of the rib falling is proportional to the height. Describes the mechanism of rib spall and proposes the rib spall prevention measures:①improve the performance of support、②Changes in physical-mechanical properties of plastic zone of coal、③damage key roof structure by external force.(3)Reasonable select of support by the calculated support resistance and ability to adapt thick coal seam with large mining height, finally determine ZZ13000/28/60 standing shield hydraulic support for 8210 fully mechanized working face with large mining height. Because the Jinhuagong Coal Mine in Datong mining area are hard roof and because of geological and technical production conditions of 8210 working face, decides that the working face by means of natural caving blasting as a supplement to manage the hard roof. At last, the hydraulic support is measured on the spot, and analysis of hydraulic support’s adaptability, further validate the importance to the reasonable selection support under the conditions of mining in thick coal seam with large mining height.