新疆下坂地水利枢纽工程深厚覆盖层防渗技术

新疆下坂地水利枢纽工程是国家和新疆维吾尔自治区的重点建设项目,坝址砂砾石土覆盖层厚达150 m,土性成因复杂多样,工程地质条件复杂,防渗难度国内外罕见.通过对深厚覆盖层地质资料的研究分析,提出“上墙下幕”垂直防渗方案,即上部采取80 m深、1.0 m厚的塑性混凝土防渗墙,下接70 m深的灌浆帷幕.水库蓄水后对防渗墙的挠度、应力应变及坝基渗流情况进行了监测分析,发现大坝防渗系统在初蓄期间工作性态良好,“上墙下幕”垂直防渗结构在深厚砂砾石覆盖层中发挥了理想的防渗效果.新疆下坂地水利枢纽工程深厚砂砾石土覆盖层“上墙下幕”垂直防渗技术的成功应用,为我国西南、西北山区同类大坝的兴建积累了宝贵的经验,为推动砂砾石土地基筑坝技术的发展提供了重要的参考和借鉴.

Seepage control technology of deep overburden in Xiabandi Water Control Project

The dam foundation of the Xiabandi Water Project is sand and gravel soil overburden, whose thickness reaches 150 m. According to the geological circumstances of the project, a scheme of ＂upper part wall and lower part curtain＂ was certified and adopted. The plastic concrete wall was 1.0 m thick and 80 m deep, and the grouting curtain was 70 m deep. ＂Drilling and splitting making trough＂ was executed in wall construction and ＂orifice-closed＂ was adopted in cement grouting. The wall deflection, stress and strain and dam foundation seepage were monitored after the reservoir impounded water. Results show that the dam seepage control system is in the early good workability state during storage, and vertical anti-seepage structure in deep sand gravel layer gets ideal anti-seepage effect. The successful example provides valu- able experience for similar dam constructions in southwest, northwest mountain areas in our country, and also promotes the development of sandy gravel soil dams.