某抽水蓄能电站上水库防渗帷幕深度优选研究

Depth optimization of anti-seepage curtain of the upper reservoir in a pumped storage power station

针对某抽水蓄能电站上水库地质条件较为复杂、库区存在两条由库内延伸到库外的中等宽度断层、副坝区基岩弱风化层较厚的特点,以及设计防渗方案不合理的问题,根据上库工程坝址区的地质结构、地形地貌及防渗帷幕设计,建立了三维有限元渗流分析模型。首先通过参数及地下水位反演确定了库区基岩的渗透系数和水库特征点处的地下水位,然后在设计防渗方案的基础上计算分析了不同防渗帷幕深度对库区渗流场、渗透流量及各部位渗透坡降的影响,并根据分析结果对防渗帷幕深度进行了方案优选。结果表明:河床断层附近和库周断层及副坝附近的防渗帷幕深度可增大10 m,左、右坝肩帷幕深度可分别减少10 m并降低至3 Lu标准,库周非断层及副坝附近的防渗帷幕深度可减少10 m。研究结果可为类似工程防渗帷幕深度方案的优选提供参考。

According to the complex geological conditions of the upper reservoir of a pumped storage power station,there are two medium-width faults extending from the inside to the outside of the reservoir and the weak weathering layer of the foundation rock mass in the auxiliary dam area is relatively thick.In addition,the designed anti-seepage scheme is impracticable.To address these problems,we established a three-dimensional finite element seepage analysis model based on the geological structure,topography and anti-seepage curtain design of the reservoir.The permeability coefficients of the foundation rock mass in the reservoir area and the groundwater levels at the typical points of the reservoir were firstly determined through inversion,then the effect of different depths of the anti-seepage curtain on the seepage field,seepage flow and seepage gradients of different parts of the reservoir were analyzed and quantified,and based on which the optimal scheme of the depth of the anti-seepage curtain was obtained.The results show that the depth of the anti-seepage curtain near the faults at the riverbed and the periphery of the reservoir should be increased by 10 m.The depth of the left and right dam abutments should be respectively reduced by 10 m according to 3 Lu standard.The depth at the periphery of the reservoir with no fault and auxiliary dam should be reduced by 10 m.The research results can serve as a reference for the depth optimization of anti-seepage curtain of similar hydraulic engineering.