Study On The Key Mining Parameters And The Surrounding Rock Control Technology Of The Remaining Coal In The Thick Seam Of Hufeng Coal

For mining of coal resources left over from the destruction of thick coal seams by the old mining method(blade and pillar type)mining,because of the complex structure of the overlying strata of the working face during the complex mining,the rationality of the complex mining face The technical parameters,roadway excavation,and support will have certain requirements.The presence of this complex structure will have a great impact on the safe and efficient production of mine-backed coal.This paper takes thick coal seam damaged by the old mining method of the old kiln of Huasheng Hufeng Coal as the research object,adopts the methods of theoretical calculation and analysis,FLAC3D numerical simulation and field measurement,and adopts the surrounding rock control and key technical parameters of the working face of the mining thick coal seam are studied in detail.The following main conclusions have been drawn:1)Based on the actual conditions of the old coal pillars in Hufeng,the theoretical calculations are used to derive the formula for the ultimate stability width of the coal pillars:Thus,the method to determine the instability of coal pillars was obtained.2)According to the stability of the coal pillars in the old empty areas,numerical simulation analysis is consistent with the theoretical calculation and analysis results.The stress distribution of the coal pillars shows a strong-weak-strong symmetry distribution,the stress value of the coal pillars is the largest,and the stress value in the middle of the coal pillars is the smallest;however,with the increase of the width of the coal pillars,the concentrated stress values on both sides of the coal pillars are The stress value in the middle has gradually decreased,and the stress value in the middle has finally reached the stress state of the original rock.3)For the stability of the top and bottom slabs in the old empty areas,through numerical simulation analysis,the stability of the surrounding rock in the remaining old empty areas is affected by the span.As the span of the old void gradually increases,the displacement of the roof also shows an increasing trend,especially since the roof begins to fall from the span of 20m and it partially falls until it completely falls;the displacement in the middle of the floor increases first and then decreases.Until the center shift is 0.4)When the old empty area has a certain span value,the larger the pillar size,the lower the probability of two old empty areas adjacent to the coal pillars from penetrating,and the old empty area roof will maintain its own stability.And the span of the old empty zone is no less than 20m,the 13m coal pillar is the limit condition for maintaining the stability of the coal pillar,and it is also the limit condition for the continuity of the neighboring old void area and maintaining the original stability of the old empty area itself.5)The rated work resistance and the initial support force of the hydraulic support of the mining face were determined.When the economical efficiency and applicability are all satisfied,the second type of mining support hydraulic support is ZFS4000/15/32,which can meet the control requirements of the surrounding mining rock for complex mining.6)In view of the characteristics of surrounding rock in mining roadway in working face,the method of“retaining belly and notching”should be adopted in the roadway of the coal mining face of Hufeng Coal Mining and the 22ath I-beam should be used as the main support roadway.7)Based on the geological conditions of the mining face and the results of the above research,the research and analysis determine the reasonable key mining parameters of the working face:the coal mining height of the mining face is preferably controlled within 2.5m,and the actual mining height is taken as 2.2m;A coal mining method with a coal mining step of 0.6m.The results of the above-mentioned main conclusions were verified by industrial tests at the 2011 mining face of Shanxi Huasheng Hufeng Coal Mining Co.,Ltd.All of them verified the rationality and achieved satisfactory results.