纳子峡混凝土面板砂砾石坝渗流监测与评价

Seepage Monitoring and Evaluation on Concrete-Faced Sand Gravel Dam of Nazixia Hydropower Station

纳子峡水电站混凝土面板砂砾石坝是高海拔、严寒地区修建在覆盖层上的最高的面板坝,其渗透安全尤为重要。该坝最大坝高117.6 m,覆盖层组成物主要为冲积砂卵砾石层,厚度为19.9~21.1 m,坝址两岸基岩裸露,岸坡及坝基均为黑云母石英片岩夹花岗片麻岩和片麻状花岗闪长岩,致密坚硬,其渗流特性复杂。通过布置渗流监测设施,系统采集混凝土面板砂砾石坝的渗流监测数据,并利用三维有限元模型进行了分析,得出了坝体的渗流量。监测与评价结果表明,大坝蓄水运行以来,坝体渗透压力及最大渗透坡降满足设计要求,水库渗流量变幅较小,且逐步趋于稳定,总的渗流量与计算结果比较接近,说明工程运行状态与设计基本接近,大坝防渗设计合理。

The concrete faced sand gravel dam of Nazixia Hydropower Station is built on 19.9-21.1 m depth riverbed overburden of Datong River,which is mainly composed by alluvial sand gravel layer,and its height reaches 117.6 m.Its penetration security is particularly impor tant.The bedrock of dam site is exposed and consists of biotite quartz schist,granite gneiss and gneissic granitic diorite,its seepage charac teristics are complex.Through the arrangement of seepage monitoring facilities,the seepage monitoring data of concrete faced sand gravel dam were collected systematically and the three dimensional finite element model was used to analyze the monitoring data.The seepage amount and seepage field distribution of the dam under different operation conditions were obtained.The results of monitoring and evaluation show that the seepage pressure and the maximum seepage slope of the dam have met the design requirements since the dam water storage operation,and the seepage flow of the reservoir is small and gradually stable,and the total seepage flow is close to the calculated results.It shows that the run ning state of the project is basically close to the design.