Study On Numerical Test Of Water Barrier Pillars For Gently Inclined Coal Seam Under Alluvium

At present, shallow coal resources increasingly exhausted in China. Mining technical conditions of deep coal resources become more complicated. It is necessary to increase recovery ratio adequately for developing coal industry in the future. Large numbers of coal resources of water barrier pillars for gently inclined coal seam under alluvium are overstocked in eastern China. Reasonable water barrier pillars scale is important significance for many coal mines.Firstly, influence factors of water barrier pillars are analyzed in the paper. It is pointed out that water barrier pillars scale is influenced by fissure developing height. Fissure developing height is related to ground stress, rock feature overlying coal seam, incline angle of coal seam, mining thickness, mining velocity. Secondly, fissure developing height of different rock combination in certain geological and mining conditions, such as, stiffness, soft, stiffness-soft, soft-stiffness, are simulated by FLAC3D software. Fissure developing height for 8m,9m,10m,11m,12m of mining thickness are simulated. In the mean time, fissure developing height are simulated for stiffness rock overlying coal seam, mining thickness 8m accordingly different coal seam incline angle 5o,10o,15o,20o,25o,30o,35o.According to numerical test results, regression formula is obtained for fissure developing height being related to overlying rock feature, mining thickness, coal seam incline angle for certain ground stress and mining velocity. At last, forecast results is in accordance with practical data.