汉江兴隆水利枢纽一期土石围堰二维渗流分析

Two-dimensional seepage analysis for powerhouse section of first stage earth-rock cofferdam of Xinglong Hydraulic Complex

汉江兴隆水利枢纽一期土石围堰坐落在50-60 m深的覆盖层上,覆盖层上层为厚15-30 m粉细砂、含泥粉细砂层,抗渗稳定性差,下层为30余m厚的砂砾石层,透水性大。围堰防渗采用塑性混凝土防渗墙上接复合土工膜心墙方案。为了解方案的防渗效果,采用二维稳定渗流模型和理正渗流分析软件,计算比较了不同防渗墙深度对应的渗透出逸比降和单宽渗流量。结果表明,悬挂式防渗墙不能有效控制渗透出逸比降和渗流量,与下部相对不透水层接触的着底式防渗墙渗流控制效果显著。

The first stage cofferdam of Xinglong Hydraulic Complex is located on the deep overburden with depth of 50-60m.The upper layer of the overburden,with depth of 15-30 m,is fine sand with mud,which has poor seepage stability;the lower layer,with depth larger than 30 m,is sand gravel which has strong permeability.The plastic concrete cutoff wall with geomembrane above was adopted as seepage control method.Two-dimensional steady seepage model and Lizheng seepage analysis software were used,and the overflow gradients and unit width seepage discharges for several depths of the cut-off wall were calculated and compared.It was shown that hanging typed cut-off wall can not effectively control the overflow gradient and seepage discharge,while touchdown cut-off wall was effective in controlling the overflow gradient and seepage discharge.