A Study Of The Segment Coal Pillar Width And Stability Of Fully Mechanized Top-coal Caving Face In Extra-thick Coal Seam

It is of great significance to study the segment coal pillar width and stability of fully mechanized top-coal caving face in extra-thick coal seam for maintaining the integrity of the mining roadway,increasing the recovery rate of coal resources and ensuring the safe and efficient production for the working face.The thesis closely focuses on the segment coal pillar width and stability of fully mechanized top-coal caving face in hard roof and extra-thick coal seam,and set W1123 working face of Kuangou coal mine as research subject.The research on reasonable width of segment coal pillar under the condition of extra-thick coal seam with hard roof is carried out with hybrid methods including field investigation,theoretical analysis,physical simulation experiment,numerical calculation and field monitoring,the following results have been achieved.Firstly,the theoretical analysis of segment coal pillar setting is completed in detail.Its mechanical model was established,and it shows that the yield zone width is 6.6m.At the same time,it obtains the reasonable size range by the size effect of coal pillar and the limit equilibrium theory.Secondly,the segment coal pillar stability was established in the physical similarity simulation experiment.This thesis reveals the law of overburden migration in fully mechanized caving face and the failure characteristics of segment coal pillar with overburden in different width coal pillar.It has obtained the number and energy characteristics of microseismic under different width coal pillar.Furthermore,it lays a foundation for studying the reasonable width of segment coal pillar in working face.Thirdly,numerical calculation is used to systematically analyze the deformation and failure characteristics,the evolution rules of stress and energy of coal pillars in different width coal pillar.When the coal pillar width is 8.0-10.0m,under the influence of mining on the working face,the internal stress of coal pillar is high,the plastic zone is connected,the damage and plastic deformation of coal and rock mass are gradually intensified.When the coal pillar width reaches 13.0-30.0m,the distribution of stress is relatively smooth,the peak value of stress decreases gradually.Meanwhile,the stability of the coal pillar continuously strengthens.On the basis of comprehensive consideration of factors such as the stability of roadway and improving the recovery rate of coal resources,the width of segment coal pillar is finally determined to be 15.0-20.0m.Finally,in-situ monitoring such as loose circle detector,borehole TV detector and stress meter of coal pillar stability is carried out in extra-thick coal seam.This thesis obtains the development characteristics of fractures in surrounding rock of coal pillar,the loosing range and the evolution law of mine pressure.It is verified that the stability of segment coal pillar under the influence of mining.This result provides theoretical support for guaranteeing the stability of segment coal pillar and safe mining in fully mechanized top-coal caving face of B2 coal seam in Kuangou coal mine.At the same time,it has certain reference value for the retention of segment coal pillar under similar engineering conditions.