Study On Overlying Strata Movement And Support Selection In Horizontal Section Mining Of Steeply Inclined And Extra Thick Coal Seam In Yimen Coal Mine

This paper takes the complex and unstable engineering geological conditions of Yimen coal mine as the research background,this coal seam has a large change in the inclination angle and a large change in the thickness of the coal seam,based on the similar material simulation experiment,numerical simulation and theoretical analysis,this paper makes a deep research on the overlying strata movement and support selection in horizontal section mining of steeply inclined and extra thick coal seam,which provides the theoretical basis for the caving mining in the thick coal seam under the complicated geological conditions of Yimen coal mine.(1)Based on the geologic conditions of Yimen coal mine,the similar material simulation experiment was used to study the overlying strata movement in horizontal section mining of steeply inclined and extra thick coal seam.The results show that the characteristics of overlying strata movement in the early stage and the later stage of the horizontal section mining of steeply inclined and extra thick coal seam are quite different,in the early stage of mining,the overburden formed a pressure arch structure,and the later stage of mining will form an articulated rock block structure;at the same time,there are many kinds of roof strata movement in steep coal seam,such as gravity sinking,moving along the normal to the bottom plate and sliding down along the bottom plate.(2)Considering the change of Yimen coal seam inclination angle and thickness of coal seam and other complex and unstable factors,UDEC software was used to simulate the overlying strata movement of different coal seam inclination angle and different coal seam thickness,and the effects of these complex and unstable factors on the overlying strata movement in horizontal section mining of steeply inclined and extra thick coal seam are studied.Research shows: the change of coal seam inclination angle and coal seam thickness directly change the stress condition and the fracture characteristics of overburden rock;the pressure cycle of the overburden fracture increases with the increase of the inclination angle,the stability of the overburden structure is weakened with the increase of the thickness of the coal seam,and the development degree of the overburden fractures increases with the increase of the thickness of the coal seam.(3)The pressure arch structure formed at the initial stage of mining,the cantilever beam structure formed in transitional stage and the stability and instability of the articulated rock block structure formed in the later stage in horizontal sectionmining of steeply inclined and extra thick coal seam were studied through the mechanical analysis,it is concluded that the main factors affecting the structural instability are the height to length ratio of the rock mass and the dip angle of coal seam,which provides the basis for the reasonable determination of working resistance of hydraulic support in working face.(4)The mechanical model of support and surrounding rock in horizontal section mining of steeply inclined and extra thick coal seam was established,the main sources of the hydraulic support load on the working face were analyzed,the reasonable working resistance of the hydraulic support of the working face was calculated,and the reasonable selection of hydraulic support was also carried out.