立洲RCC拱坝渗控方案的三维有限元优化分析

以四川木里河立洲水电枢纽工程为研究对象,对坝区的渗控措施展开研究。利用ANSYS12.1建立三维有限元渗流模型,计算分析得到了各渗控方案的渗流特征和渗透压力变化规律。对各方案中关键部位的渗透比降、渗漏量和典型剖面渗流场的渗压、地下水位等特征量进行比较分析后,得知:(1)立洲拱坝渗控措施设计方案的防渗帷幕和排水孔幕能有效降低坝后渗流浸润线,对于减小坝基、坝肩扬压力、改善坝基和坝肩受力条件起到了良好的作用;(2)加深帷幕和排水孔幕、增厚帷幕对降低坝区渗透压力作用不大;(3)适当增加f5断层附近防渗帷幕的深度,可防止f5断层形成渗漏通道,影响坝区渗透稳定;另外,取消第一层排水幕、缩短坝肩防渗帷幕延伸长度,可使渗控措施在满足渗流安全的前提下更为经济。

Three-dimensional Finite Element Optimization Analysis of Different Seepage Control Schemes of Lizhou RCC Arch Dam

The seepage control measures were investigated for the dam area of Lizhou hydroelectric project in Muli River of Sichuan Province. A three-dimensional finite element seepage model was developed using ANSYS 2.1 to analyze the seepage characteristics and variations of seepage pressure under different seepage control schemes. The seepage gradient and seepage amount of key positions and the seepage pressure and groundwater level of typical profiles of seepage field for different seepage control schemes were compared. The results showed that (1) the impervious curtain and drainage hole in the design scheme of seepage control measures of Lizhou arch dam can decrease the seepage saturation line effectively, lower the uplift pressure on dam foundation and dam abutment, and improve the stress conditions of dam foundation and dam abutment; (2) the deepening curtain, drainage hole, and thickening curtain have insignificant effects on decreasing the seepage pressure; and (3) increasing the depth of impervious curtain near the f5 fault can prevent the formation of leakage passage in the f5 fault. In addition, removing the drainage hole in the first layer and decreasing the extending length of the impervious curtain of dam abutment can save the cost of seepage control measures without breaking seepage safety.