Research On The Development Law Of "three Belts" In The Roof Of 1805 Working Face In Wulunshan Mine

This paper takes the working face of no.8 coal seam 1805 in wulunshan coal mine of guizhou wulunshan coal industry co.,LTD as the research area.The coal seam has the problem of great difficulty in gas extraction.After gas extraction,the gas content in some areas is still higher than 8m~3/t.Based on 8 coal roof of 1805 face MaoLaDai,height of fractured zone and bend subsidence zone division and development situation of the research,obtained 8 coal roof overburden deformation and failure development regularities,guide the five rounds mountain coal 8#coal seam roof water prevention and control work,and the upper adjacent 6#coal seam of coal seam gas extraction,strengthen the 8#coal bed and upper minable seam gas management,and provide guidance for similar mining conditions of coal mines.In order to grasp the movement of the overlying rock affected by the excavation of coal seam,FLAC~3DD numerical simulation of excavation process,analyzed the coal seam in the process of excavation of overlying rock stress,displacement and plastic deformation.After coal mining,the stress distribution form of overlying strata is trapezoid along the coal seam strike profile,and the stress increases gradually from the center to both feet.The vertical stress is rectangular with rounded corners,and the range of rectangles increases with the increase of excavation depth.On the horizontal section,with the increase of vertical height from the roof,the vertical stress distribution is oval.The total displacement of overlying strata is mainly downward displacement and close to the center of goaf.According to the situation of the scene and empirical formula to calculate the fracture zones is expected maximum height of 36.8 m,observation of drilling hole location choice in 1805 face down 5#drill yard,roof opening height 2.4 m,arrangement of three observation hole,using YTJ-20 layers detecting recorder borehole imaging method for static observation.The WBD-type 1 network parallel electrical method for dynamic monitoring,monitoring of drilling hole location choice in cis 1#drilling yard roof of 1805 face,no.1 bore detection for elevation,the actual drilling elevation is 64,and the roadway between Angle of 60,to face the side,used for monitoring the fissure zone development.No.2 drilling and drilling hole in the same position,1 elevation is34°,60°Angle between roadway and,to face the side,for monitoring MaoLaDai development process.Two kinds of methods to confirm each other,realize the regional dynamic monitoring combined with local static observation,determine MaoLaDai development after mining height is 7~9 m,development of fractured zone height of30~37 m,more than 37 m section of roof strata rock for bending subsidence zone.The roof of no.8 coal seam is not the main key layer of the formation of the rock formation,and 8.07m fine sandstone is the key layer.The main key layer decides the height of the height of the goaf in 1805.The rock breaking in the process of mining,sliding instability caused by roof deformation,forming 8 coal mined-out area and adjacent layer 6-3 coal seam gas emission channels,6-3 coal seam gas influx of 1805working face.