Study On The Reasonable Width Of Section Coal Pillar In Fully Mechanized Heigh-wall Mining Face In Shallow Seam

The coal seams of Shenfu mining area are thick coal seams and shallow deposited,and the fully mechanized heigh-wall mining method are widely used.The reasonable width of the sectional coal pillar in the longwall face has a direct impact on the safety of the entry and mining face,and it also affects the coal recovery rate.In this paper,the research background is the heigh-wall mining in Zhangjiamao coal mine.Based on field measurement analysis,numerical simulation and theoretical calculation,the reasonable width of the sectional coal pillar in shallow coal heigh-wall minig is studied.Based on the condition of mining face in No.5-2 coal seam of Zhangjiamao coal mine,the strata pressure monitoring scheme is established,and the roof weighting as well as overburden load are measured.By using the limit equilibrium theory of rock mass,the monitoring scheme of sectional coal pillar abutment pressure and broken zone are established,the result is that the width of plastic zone and broken zone of coal pillar are 1.2m and 0.8m in the shallow coal seam heigh-wall mining.The deformation,and failure characteristics as well as pressure distribution of coal pillars with different width are analyzed by using the FLAC3D numerical calculation software.The stability and reasonable width of sectional coal pillar are demonstrated.It is concluded that the width of the coal pillar elastic core zone is close to the theoretical limit after the sectional coal pillar width of the No.5-2.coal seam is optimized from the original 17.6m to 19.2m.On the basis of pressure arch theory and Wilson theory,according to the overburden caving feasure in shallow coal seam,the hopper load model of section coal pillar is presented.Based on the hopper load model,combined with the theory of limit equilibrium and shallow hard coal seam characteristics,the theoretical calculation formula of coal pillar average sress and the reseanable width are put forward,and the optimized coal pillar width of 17.6m is verifiedThis research provide a theoretical basis for the reseanable sectional pillar design of the No.5-2 coal seam in Zhangjiamao coal mine,and it also provide a reference for similar coal pillar width design.