乌东德水电站首次蓄水期坝基渗流控制效果评价

Evaluation on seepage control effect of extra-high arch dam foundation during first impoundment period:case of Wudongde Hydropower Station

在特高拱坝首次蓄水期,对坝基渗流控制效果进行评价是保障大坝安全的重要依据。以岩溶地区300 m级特高拱坝乌东德水电站坝基为例,利用监测成果分析、测试分析、工程地质分析等手段,分析了首次蓄水期坝基渗流变化规律及分布特征,以及蓄水过程中产生的局部渗漏问题,评价渗流控制措施的工程效果。结果表明:乌东德水电站首次蓄水完成后,幕后渗压折减系数一般为0.08~0.27,最大0.40,均在规范允许范围;幕后山体地下水位增加0~13 m,幕后排水孔出水总流量6.5 L/s,总体变化均较小;水化学与地质信息表明右岸733 m灌浆平洞局部渗水来源主要为坝后水垫塘。综合表明,坝基扬压力正常,渗漏量总体较小,渗流状态趋于平稳,大坝防渗帷幕及排水幕效果理想,在同类工程中处于较优水平。

During the first impoundment period of extra-high arch dams,the evaluation on seepage control effect is significant for dam s safety.For Wudongde Hydropower Station,a typical 300 m high arch dam in karst region,we used monitoring data,test analysis and engineering geology to analyze the variation and distribution of dam foundation seepage,identify local leakage positions,and evaluate the effect of the seepage control measurements.The results showed that after the first impoundment of Wudongde Hydropower Station,the reduction coefficient of seepage pressure behind the curtain ranged from 0.08 to 0.27 with the highest value of 0.40,which were within the allowable range of the standard.The groundwater level of the mountain behind the curtain increased by 0~13 m,and the total discharge amount of drainage holes behind the curtain was 6.5 L/s.According to the analysis of water chemistry and engineering geology,the seepage at elevation of 733 m grouting curtain was mainly from the water cushion pond behind the dam.The comprehensive analysis showed that the seepage uplift pressure of the dam foundation was normal,the amount of seepage leakage was generally small and the anti-seepage curtain and drainage curtain of the dam had a good effect,being a relatively supreme position among similar projects in China.