Control Technique Of The Downhill Roadway In Close Distance Seams Of Huacaotan Coal Mine

When the distance between adjacent coal seams is small,the stress concentration has caused different degrees of damage to the downhill of the mining area.It is of great significance to study in-depth all aspects of the mining of the short-distance coal seams,such as the structure of the rock stratum,the distribution of the overburden stress,the law of the coal pressure appearance in the working face and the stability control of the surrounding rock in the downhill.In this paper,the field investigation method,combined with numerical simulation and theoretical calculation analysis,is used to systematically study the stress distribution characteristics of the surrounding rock under multiple disturbances in the first mining area of huacaotan coal mine.Based on the analysis of the pressure arch appearance and stress transfer around the surrounding rock under the action of different mining sequences,the "full section prestressed anchor cable anchoring" system is proposed and successfully applied to the project actual.The main research results of this paper are as follows:(1)Based on the FLAC numerical simulation method,the stress distribution characteristics of the surrounding rock in the downhill under the influence of multiple mining disturbances,different stoping line positions and different mining sequences are studied.The surface displacement characteristics of the surrounding rock are analyzed.The failure of the original support system in the downhill and the causes of the deformation of the downhill track are discussed.(2)Under the influence of surrounding rock stress distribution,the deformation characteristics of the downhill of the track will form a pressure arch,which has a certain stabilizing effect on the surrounding rock.The mining sequence of the working face has more influence on the displacement of the roadway floor and the surrounding rock of the side,and the deformation of the surrounding rock of the track downhill shows a certain degree of asymmetry.(3)According to the influence range of the leading bearing stress,the influence range of the surrounding rock deformation of the main roadway and the related range of the sensitivity of the stability of the coal pillar between the roadway and the working face represented by the peak stress coefficient,the position distance of the stoping line of the working face is 2 × coal seam level and 50 m from the downhill.(4)Using numerical simulation,the influence of axial force distribution and parameters of non prestressed common anchor cable and prestressed anchor cable on the sensitivity of deformation and failure of downhill surrounding rock is compared.Combined with the maximum plastic failure range of surrounding rock calculated by theory,the whole section anchor cable anchoring system is proposed and the reasonable values of parameters(prestress of anchor cable,length of anchor cable,spacing between rows,etc.)are determined.(5)Based on the supporting mechanism of track downhill,combined with the engineering practice of track downhill surrounding rock in No.1 mining area,the technical advantages of full section prestressed anchor cable support are analyzed.The adopted supporting technology is applied to the engineering practice,and the surface deformation of track downhill surrounding rock is controlled.Through field observation and overall evaluation of mine pressure monitoring,the stability of track downhill surrounding rock is good,which meets the engineering requirements.There are 52 figures,7 tables and 87 references in this paper.