Research On Stability Of Fractured Coal Seam Wall In Large Mining Height Working Face

ShenNan mining area is a typical large modern mining area in the development of Jurassic coal seam in North shanxi.Mining area in the south has the great thickness of coal seam,coal hardness.The coal cutting power consumption is large and the safety hidden danger is high in the comprehensive mechanized production of large mining height.In this regard,this combination of Shennan mining area coal mine fully mechanized high softening project Hong Liulin coal seam hydraulic fracturing such loose and large mining,using the method of field monitoring,theoretical analysis combined with numerical simulation,the stability of the coal wall of Hong Liulin coal mine fully mechanized face with large mining height coal seam fracturing expansion research,the main research contents and conclusions are as follows:(1)The establishment of coal seam fracturing mechanical model of instability failure analysis,coal wall spalling of coal seam fracturing,determine the mechanical condition of failure of coal seam fracturing failure,coal wall spalling of coal seam fracturing instability are bulging and spalling occurred in the first place for 0.35 times mining height and provide a theoretical basis for the point.For the fractured coal.At the same time,analysis of fractured coal seam roof happen rotary damage,direct top "plastic cushion" of "absorption" and "ease"roof pressure,roof pressure when the roof rock fracturing of coal body deformation times rotary absorption,coal wall abutment pressure transferred to the front of the working face,spalling failure the steady phenomenon did not occur in the coal wall fracturing area.(2)We can use analysis before and after fracturing of coal samples stress-strain curve to find that coal seam hydraulic fracturing,changed the overall mechanical properties of coal,improve the degree of development of fissures of coal,increase the coal wall of the plastic zone,reduce the coal strength and brittleness,plastic deformation ability improved so,the coal stress concentration peak shifts to the depths of the coal body,reduces the coal wall at the level of the peak stress,reduced the coal wall of horizontal and vertical displacement,effectively control the stability of the coal wall,reducing the risk of loss of coal wall stability.(3)By using FLAC3D numerical simulation analysis on the relationship between support and surrounding rock coal seam fracturing simulation software,with hydraulic support’s strength increased,the abutment pressure peak position in front of the working face is not changed,but the abutment pressure peak size significantly decreased after coal seam fracturing can change the abutment pressure peak the location,and reduce the abutment pressure peak value.