Pressure Relief At Cutting Top Of Mining Face Study On The Regularity Of Mine Pressure In Retaining Small Coal Pillar

In the green mining of coal mines,roadway driving with small coal pillars in the active face can effectively solve the tight situation of mining and excavation.However,the dynamic pressure of the mine is affected by the dynamic pressure,and the roadway deformation is extremely serious,and the existing surrounding rock control technology cannot be compared.A good solution to this problem seriously restricts the safe and efficient production of coal resources.The technology of cutting the roof and leaving small coal pillars to protect the roadway in the moving working face has important theoretical value and practical significance for solving this problem.The pre-splitting blasting roof cutting method can effectively weaken the stress transmission path of the force transmission structure such as the cantilever rock beam and the basic top arc key block formed on the side of the mined-out area,and enable the gangue to fill the mined-out area in time to form an effective support for the overlying roof.Thereby reducing the impact of the dynamic pressure on the stability of the roadway.This paper takes the 1102 working face of Fusheng Coal Industry 15#coal seam while the 1106 working face is transported along the trench and the 1102 transport along the channel is advanced pre-splitting and roofing as the research background.Field investigation,laboratory test,theoretical analysis,and numerical simulation are used.And engineering practice and other methods,study the mining pressure on the top of the mining face to relieve pressure and leave small coal pillars to protect the roadway pressure behavior law.The main research results are as follows:(1)Through on-site drilling and peeping and core drilling,combined with the collection of relevant geological data,the occurrence of 15#coal seam and the distribution of the roof and floor rocks of 1102 and 1106 working faces were clarified;laboratory tests revealed 15#coal seam coal rock mass Based on the key layer theory,the position of the sub-key layer in the rock formation within 40m of the working face is determined.(2)Compared with the traditional overlying rock structure of the roadway when driving along the gob,the control mechanism of the surrounding rock of the cut-top and pressure relief is analyzed;the mechanical model of the rock beam of the second sub-key layer under the support of the collapsed gangue accumulation in the goaf is established Analyze the bending deformation characteristics of the second sub-key layer;the roadway is divided into five stages during the whole process of cutting the roof and leaving small coal pillars,and the failure process of the roadway covering rock structure and the surrounding rock stress in each stage are analyzed.State distribution.(3)Using FLAC^3Dnumerical simulation software,the stress evolution characteristics and displacement change laws of the surrounding rock of the roadway in the process of facing mining and excavation with or without roof cut were studied,and they were divided into 4stages;compared and analyzed with or without roof cut.Based on the stress and displacement of the surrounding rock of the roadway,it is concluded that the peak value of the internal stress of the coal pillar and solid coal wall after roof cut is 55.9%and 35.8%lower than that without roof cut,the distance between the roof and floor of the roadway and the convergence of the two sides The largest reductions are 39.5%and 35.1%;at the same time,the evolution characteristics of roadway stress and displacement during the mining process of this working face after roof cutting are analyzed.(4)Based on the results of theoretical analysis and numerical simulation,the 1106transportation channel support plan was formulated and applied to on-site industrial tests;according to the results of mine pressure monitoring,it was concluded that the mining range was 50m ahead to 80m lagging behind,and the roof and floor The cumulative deformations of the two sides and the two sides are 74mm and 71mm,and the maximum stress concentration factors of the pillar sides and solid coal sides are 2.10 and 2.72;the leading influence range of the stoping in this working face is 40m,and the cumulative deformations of the roof and bottom plates and the two sides are 223mm and 195mm.The maximum stress concentration coefficients of coal pillar and solid coal bank are 3.31 and 3.96.The effective control of the surrounding rock of the roadway under the mining face with small coal pillars is realized.