Study Of Drainage For Limestone Water Of Coal Floor Based On Visual Modflow

The study area of this paper is the first mining district of Wolonghu coal mine which covers 3.84km2. The first mining coalbed is coalbed NO.10 in the middle of the Shanxi formation. The Taiyuan formation limestone aquifer abounds karst, which below 50 meters under coalbed NO.10 in the first mining district. The limestone water pressure of coalbed NO.10 floor was calculated, which is between 0.24MPa and 5.6MPa while the water-pressure of the Taiyuan formation limestone roof is between 2.8MPa and 6.0MPa. The water bursting coefficient of coalbed NO.10 floor of the first mining district is between 0.06MPa/m and 0.16MPa/m, which exceeds 0.06MPa/m. So the Taiyuan formation limestone water is the most important water hazard in Wolonghu coal mine during mining coalbed NO.10. In this paper, mining safety was implemented during mining coalbed NO.10, against limestone water hazard of the first mining district of Wolonghu coal mine under coalbed NO.10 floor. So the study of drainage limestone water under coalbed NO.10 floor was carried out.Because of the pumping test of limestone water is not carried out for the study area,the numerical simulation of underground boring's drainage course for the study area is carried on by use of Visual Modflow in this article, the results are also analyzed in this article. the drawdown distribution of water level are obtained, which can supply the theory gist for pumping and depressurizing of Taiyuan formation 's limestone water in the process of mining coalbed No.10.Based on the analysis of geological and hydrological data of Wolonghu coalmine, karst water-bearing media system was generalized and the hydrogeological conceptual model of the first mining district of Wolonghu coal mine was set up by analyzing the hydrogeological characteristics and the dynamic characteristics of groundwater of the study area. The model is homogeneous anisotropy, double-decker and confined of 3D unsteady fluid flow model. Furthermore, a more dependable 3D groundwater mathematical model was set up on this model. The numerical simulation of groundwater was researched by the international advanced Visual Modflow software and simulates groundwater flow field changing regularities. Moreover,the study of underground drainage research was proceed in the simulation model. The drawdown distribution of water level under different drainage capacity and time are simulated, according to the numerical modeling results, the scheme of dewatering orifice's position, quantity and required drainage time are designed: when dispose three dewatering orifices in the rock drift of the first mining district, and the maxima drainage capacity is 1320m3/d, at 30～90 days the water level drawdown varied can attain to 20～135m, of which the effect is versus prominence. The drainage program of Taiyuan formation limestone water of the study area is appraised in this article; it can reach the desired rates of drainage depressurizing for the study area, and indicate that it is approvable to carry on the drainage depressurizing prevention and cure water measure. After verification of the drainage program, the result of the simulation indicated that the model accorded with the local actual hydrogeological very well.Above all, the groundwater numerical model which fit the study area was explored and application of Visual Modflow software to the prevention technologies of the coal floor limestone water. In order to prevent the coal floor water bursting during mining coalbed NO.10 and realize safely and efficiently production, the property of dredging of the coal floor limestone water was studied, the location of depressing bore was suggested, suitable control measures were selected and drainage quantity was calculated.