分布承压黏土隔水层的坝基深厚覆盖层防渗研究

Study on Seepage Control of Deep Overburden of Dam Foundation with Distributed Pressure-bearing Clay Insulation

MRKQT水利枢纽工程坝址处河谷宽度1450m,覆盖层最大厚度206m,既有自上而下结构逐渐密实、多点分布透镜体状砂层、粉土层的整体性,又有中部分布两层连续隔水层及对应承压含水层的独特典型特征。从坝基防渗处理底部隔水层选择入手,分析隔水层①以下覆盖层覆盖层渗漏可控性和安全性;又从施工期、运行期不破坏隔水层①现状整体性为前提,拟定3组较常用的覆盖层防渗处理方案进行计算分析,初选防渗墙全封闭方案及防渗墙采用柔性材料。

The Valley width and maximum thickness of overburden at the dam site of MRKQT hydraulic complex are 1450m and 206M respectively.It has not only the integrity of lenticular sand and silt layers with gradually compact top-down structure and multi-point distribution,but also the unique typical characteristics of two continuous water barriers and corresponding confined aquifers in the middle.Starting with the selection of bottom water-proof layer for dam foundation seepage-proofing treatment,this paper analyses the seepage controllability and safety of overburden layer below water-proofing layer①.On the premise of not destroying the integrity of water insulation layer①during construction and operation period,3 groups of commonly used treatment schemes for seepage prevention of overburden are proposed for calculation and analysis.Finally,the scheme of full closure of cut-off wall is selected,and the flexible material is used for the cut-off wall.