| Shaanbei Shennan mining area is located in the edge of Maowusu desert, the hydrogeological condition is relatively complex, especially the south limb of Ningtiaota Coal Mine is more complicated. The first coalface S1210 in south limb have happened water inrush accident, which lasted for longer time and large water inflow, forcing S1210 coalface stop working. S1224 as the rearranged first coalface in the south of west roadway in Ningtiaota Coal Mine, how to make a accurate and reasonable dynamically prediction of the water inflow in this coalface, has a strong guiding significance for the prevention and control of water in S1224 coalface.This text mainly based on the geological, hydrogeological and engineering geological data of the south limb in Ningtiaota Coal Mine. And choose S1224 coalface as the main research object, application of the rock and soil hydraulics theory and numerical simulation method realized the dynamically prediction of the water inflow in mining forward different distance of S1224 coalface. After the working face mining, the development of the mining-induced fractures in the overlying strata, and when the mining-induced fractures touch the aquifer, has become a good water flow channel, that is the water flowing fractured zone.The relationship between hydraulic conductivity and stress of fractured rock mass is established by the hydraulic theory of rock mass, and the relationship between the strain and hydraulic conductivity of mining rock is deduced. Based on the FISH language, realized the coupling calculation of the fractured rock mass hydraulic conductivity and strain in FLAC3 D Fluid-solid Coupling Model Analysis System, and made a research of the overlying strata hydraulic conductivity change law on S1224 coalface after mining the 2-2seam. The calculation results show that the shape and developmental range of vertical hydraulic conductivity increases area and the horizontal hydraulic conductivity increases area in the process of advancing the working face are different. Vertical hydraulic conductivity increases area shape is symmetric distribution central of mined out area of "M" shape, in coal wall andopen-off cut both sides highest development. Horizontal hydraulic conductivity increases area shape from just when mining "semi elliptical" slowly turns into "ladder" shape, and the highest of increases area is right upper in the center of mined out area. Finally,using the MODFLOW module of GMS software established the 3D hydrogeological numerical model, and predicted the water inflow of S1224 working face by unsteady flow calculation. Results show that the water inflow of S1224 working face is relative large, with the advance of working face, the water inflow can be divided into four stages. The first stage of water inflow is the rapid increase stage(0~300m), the water inflow by the 2.36m3/h increased to 620m3/h, the second stage is the basic stability stage(300~700m), the water inflow of working face is stable at620m3/h, the third stage is gradually reducing stage(700~900m), water inflow gradually reduced to 420m3/h, the fourth stage is the final stable stage(900~2000m), the water inflow of working face is finally stable at 420m3/h. Based on the prediction results, the suggestions for the prevention and control of water in working face are put forward. At the same time, this is a new method to predict the water inflow of the working face in this paper, this new idea can be applied to predict the water inflow at different distances of other coal mine working face before mining. |
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