截水帷幕技术在元宝山露天煤矿的应用与效果评价

内蒙古元宝山露天煤矿是国内外罕见的特大富水型露天煤矿，为解决多年疏干排水造成的生产成本高和环保风险大等问题，拟采用截水帷幕技术对矿坑渗流补给通道进行帷幕截流。通过分析矿坑水文地质和工程地质条件，提出弧形半封闭落底式帷幕与群井疏干水力帷幕相结合的地下水控制方式，采用防渗膜垂向隐蔽叠覆铺设与抗渗混凝土充填工艺，在矿坑高程+452 m平盘开展帷幕试验研究，建造一座平面长度1 369 m、平均深度29 m、有效厚度大于0.8 m、底部嵌入基岩面3 m的截水帷幕。试验研究过程中，确定了元宝山露天矿的截水帷幕工艺，获得其单幅槽段开挖长度(14 m)、护壁泥浆密度(1.05~1.25 g/cm3)和防渗膜叠覆宽度(1 m)等主要技术参数，提出防渗膜水下磁吸式连接技术，通过加装磁条，利用阴阳磁吸原理实现防渗膜叠覆处的水下自粘连。试验工程结束后，通过取心验证、流场分析和流量变化等方法检验帷幕墙的质量和截水效果。结果表明:混凝土浇筑充填连续、密实；墙体内外水位差已达15 m以上；盲沟补给流量消失，截水效果显著。试验研究证实截水帷幕技术适用于元宝山露天煤矿，为后续工程开展提供了关键技术参数，完善了我国露天煤矿截水帷幕技术体系。 

Application and effect evaluation of water cutoff curtain technology in Yuanbaoshan open-pit coal mine

Yuanbaoshan open-pit coal mine of Inner Mongolia is a rare extra large water rich open-pit coal mine at home and abroad. In order to resolve the problems of high production cost and high environmental risk caused by drainage for many years, it is plan to adopt water cutoff curtain technology to closure the seepage supply channel. By analyzing the hydrogeological and engineering geological conditions of the mine, the groundwater water control method of combining arc semi-closed curtain with group wells drainage hydraulic curtain was proposed. The curtain test study was carried out in the mine 452 m flat plate by using the vertical concealed overlay laying of geomembranes and the filling process of impermeable concrete. A water cutoff curtain with a plane length of 1 369 m, an average depth of 29 m, an effective thickness > 0.8 m and bottom embedded in bedrock surface of 3 m was built, During the test study, the technology of water cutoff curtain was determined in Yuanbaoshan open-pit mine. The main technical parameters such as the excavation length of single trench section (14 m), the retaining wall mud density (1.05-1.25 g/cm 3) and the overlapping width of the geomembrane (1 m) were obtained, and the technology of underwater magnetic suction connection of geomembranes was put forward, by adding magnetic strips, the underwater self-adhesion of the geomembrane overlaps on the principle of Yin-Yang magnetic suction was accomplished. After the experiment project, the quality and water interception effect of curtain wall were tested by drilling verification, flow field analysis and runoff changes. The results show that the concrete pouring and filling is continuous and the water level difference between inside and outside of the wall has reached more than 15 m; the recharge flow of blind-ditch disappears, and the water interception effect is remarkable. The experimental research proves that the water interception curtain technology is suitable for Yuanbaoshan open-pit coal mine, and provides key technical parameters for the follow-up project, improves the water interception curtain technology system of open-pit coal mine of China.