日冕水电站心墙堆石坝坝体渗流场初步分析

日冕水电站心墙堆石坝最大坝高达346 m，坝体的渗流，尤其是心墙的渗流，对大坝的安全至关重要。采用有限元计算方法，对多种条件下的大坝渗流场进行了计算。通过计算成果的对比分析，认为在反滤层Ⅰ与心墙渗透性相差10倍以上、心墙坡比为1∶0.25时，大坝分区和渗流场分布比较合理；在反滤层Ⅰ与心墙渗透性相差较小、心墙坡比更陡的条件下，心墙的安全性将更加依赖于反滤层的保护。针对水电站水位以8 m/d的速度连续下降5d的较不利条件分析非稳定渗流场，结果表明：上游坝壳内的自由面几乎同步下降，对上游坝壳渗透稳定和坝坡稳定影响不大。研究成果为水电站预可研阶段设计提供了参考依据。

Preliminary Analysis on Seepage Filed in Core Wall Type Rockfill Dam of Rimian Hydropower Station

The dam of Rimian Hydropower Station is a core wall type rockfill dam with height of 346 m. The situation of seepage field in the dam ,and especially in the core wall, is very important to the dam safety. The seepage field under different conditions was simulated with finite element method. In comparison with the simulated results, it is concluded as follows： The dam zoning and the seepage field distribution are reasonable while the filter layer Ⅰ is more permeable than the dam core with 1 magnitude and the ratio of the core wall slope is 1∶0.25. However, the safety of the core wall would much more rely on the protection by filter layer if the permeability difference is less and the core wall slopes are steeper. The transient seepage field is simulated under the condition that the reservoir water level falls in 5 days with speed of 8 m/d. The results indicate that the phreatic surface in the upstream dam shell falls almost synchronously with the reservoir water level, and the small hysteresis would not worsen greatly the seepage and the slope stability. The research results provide important references to the design of the dam at the pre-feasibility study stage.