Numerical Simulation Analysis On Groundwater Inflow To The Coal Seam Mining Around A Bulky Fault

Fault F2 of HuaiBei Taoyuan Mine is a normal one,with a strike of N80-88°W,a dip of NNE,a hade of 40°～60°,and a throw of more than 400m. NO.10 coalbed in Northern Mining areaⅥ-8 lies upon it,where water inflow in the gob is supplied by aquifers of Ordovician limestones,Archaean era limestones as well as Coal roof sandstones in the opposite side.According to the thickness of every stratum in the mining area, the hydro-geological parameters, and the location of NO.10 coal,fault,the aquifers of Ordovician limestones, carbonic limestones floor and sandstone crack water in coal stratum,a three-dimensional steady flow model can be established by the Visual Modflow to show the three-dimensional spatial location of Fault F2 and make a numerical simulation analysis on water inflow of the gobs that are 100m or 700m in length.By using Illustrator drawing software to clip the maps outputted,the gobs will be presented in a translucent way to demonstrate the three-dimensional spatial relationship.See from the equipotential water head line outputted by the simulation,the water head around the gobs change greatly in gradient,while the equipotential water head tend to be dense. The section where the density is more obvious lies around the cut hole region. The reason is that this part is much closer to the fault so as to be influenced by Ordovician limestone water. Besides, the gob floor at the coal face is so near the carbonic limestones aquifers that this part is also involved in the influence of the carbonic limestones high-pressure water. It can also be told from the simulation velocity vector diagram and the velocity direction schematic diagram that the aquifers of all the three areas of Archaean era limestones,Ordovician limestone and the top part supply water to the gobs, where around the corners of the fault, the current speed arrives its highest; the recharge from Ordovician limestone aquifer to the fault water is not evenly distributed, that is, the nearer the gob is to the fault, the higher the velocity is; and the velocity vector of both the top part and the bottom part toward the gob is parallel to each other, which accords with the practical rules. The amount of water which the aquifers of Ordovician limestones,carbonic limestones and the sandstone crack water in coal stratum recharge the gobs can also be obtained through the simulation:Recharge from Ordovician limestones is the most among the three, that from Carbonic limestone takes the second place, and that from the upper part is the least.When the length of the gobs increases from 100m to 700m, the water inflow floating from the aquifers of the Ordovician limestones and the Carbonic limestones to the gobs rises respectively by 12.38m3/h和3.26m3/h.That is to say, the increasing amount of the formmer is larger than that of the latter, and water from the top part of the aquifers changes little in amount, less than 1m3/h.