牙根二级水电站坝区渗流场分析与渗控效应评价

Simulation of Seepage and Its Control Effects at the Dam Site in Yagen-II Hydropower Station

牙根二级水电站坝址区河谷狭窄,岸坡陡峻,地质条件复杂。水库蓄水后,坝体、坝基及两岸绕坝渗流将成为影响工程安全和正常运行的重要因素之一。综合分析地形地貌、地质构造以及防渗排水方案的特点,建立坝区三维有限元模型,采用子结构、变分不等式和自适应罚函数相结合的方法(简称SVA方法),结合典型挡水坝段与坝区整体渗流场分析成果,研究了坝区渗流场分布特征,分析了排水孔幕间距以及碾压混凝土层间渗透性对渗流场的影响,并对防渗排水措施的渗流控制效率进行了评价,从而为工程建设提供合理的建议。研究表明,坝区渗流控制措施布置合理,防渗排水效果显著;排水孔幕的布置对坝基扬压力起控制性作用;碾压混凝土渗流特性的各向异性对大坝渗流自由面的性态有显著影响。

Located in a narrow and deeply-cut valley in the middle course of the Yalong River,Yagen-II Hydropower Station has the necessity of considering the dam seepage condition due to its complex geological conditions,since the dam seepage will become one of the important factors affecting the safety and the normal operation of the project after the impoundment of reservoir dams.For performance assessment and optimization design of the seepage control system,a numerical method combining a substructure technique,a variational inequality formulation of Signorini＇s type and an adaptive penalized Heaviside function（short for SVA method）is adopted.Combined with the typical dam section and the whole seepage field analysis results,the characteristics of seepage field is studied,the effect of drainage curtain spacing and RCC interlayer permeability on seepage field are analyzed.Research shows that,the seepage control measures are reasonable and the seepage control effect is significant.The arrangement of drainage curtain plays an important role in controlling uplift pressure of dam foundation;An isotropic seepage characteristic of RCC has a significant influence on the dam seepage free surface.