Study On Surrounding Rock Control Technology Of Gob-side Excavation In Fully Mechanized Caving Face With Large Mining Height

Large mining height are broken roadway driving along goaf caving mining face roadway drivage compared with general,roadway under high pressure,the deformation of surrounding rock is serious,and the mine pressure appear obvious asymmetry,the large mining height are broken roadway driving along goaf caving mining face in this coal pillar width problems and rational support plan and parameters for the stability control of roadway driving along goaf is crucial.Taking the 946 fully mechanized caving face ii of Luling Coal Mine as the research background,this paper studies the width of small coal pillars,the characteristics of mine pressure and the support design of gob-side caving face with large mining height.The main research conclusions are as follows:(1)Analyze several stages of excavation roadway affected by dynamic pressure in goaf,and establish overburden rock structure mechanical model of excavation roadway along goaf with large mining height.According to the calculation formula,the location of fracture line is about 1.6m away from the edge of coal wall in goaf,and establish coal pillar width calculation model,and the theoretical width of small coal pillar is about 3.91m.The stress and deformation law in the roadway and in the coal pillar under different coal pillar widths were compared,and the reasonable width of the small coal pillar was determined to be 4m.(2)The supporting parameters of bolt and cable are calculated,and the deformation law of surrounding rock of roadway without support and after support is studied by numerical simulation.The results show that:without support,surrounding rock is rapidly destroyed after roadway excavation,roof and coal pillar are basically broken,and the damage degree is serious;The displacement of goaf side wall is obviously larger than that of solid coal side,and the deformation is asymmetrical on both sides.The supporting scheme was designed based on the law of mine pressure appearing in the unsupported roadway.Through the numerical simulation results,it was found that the support strength of the goaf side roadway wall and roof was not enough after the support,and it was necessary to strengthen the support.(3)to analyze the cause of the support strength is not enough,complete is obtained by uniaxial compression test of compressive strength of coal,use PFC simulation prefabricated crack under uniaxial test of coal is found in the fissure of coal is a certain development,reducing its compressive strength,about one-third,shows that crack would help significantly reduce along the empty side of the lane,and along the empty side of roof strength,lead to support failure.Aiming at the problem of insufficient support strength,the supporting scheme was optimized,and the stress,displacement and deformation law of supporting structure were analyzed by numerical simulation and insitu mine pressure observation.The results show that the optimized supporting scheme is effective and can stably control the deformation of surrounding rock along goaf.Figure[89]Table[3]Reference[82]...