瀑布沟大坝蓄水期心墙应力分析

Stress Analysis for the Core-wall of Pubugou Dam During Impoundment

以瀑布沟水电站蓄水期监测资料为基础,对大坝心墙内孔隙水压力、土压力及两者的关系进行分析。分析结果表明:在瀑布沟水电站的整个蓄泄水过程中,孔隙水压力随水位的升高而增大,反之亦然;大坝横断面方向,从上游往下游,渗压与库水位的相关性依次减小,库水的入渗是心墙渗压变化的决定性因素;土压力变化与孔隙水压力变化规律基本一致,土压力值调整是蓄水引起的渗流、固结共同作用的结果,主要受上游水位的影响;在水库蓄水过程中,有效应力下降,孔隙水压力占土压力的百分比达到100%,可能发生局部水力劈裂。总结蓄水期砾石土心墙渗压和土压力变化规律,可供其它同类工程参考。

On the basis of monitoring data of Pubugou Hydropower Station during its impoundment, we analyzed the pore water pressure, soil pressure in the core-wall and the relationship between them. Results show that： during the storage and discharge of water in the Pubugou Hydropower Station, the pore water pressure increases along with the rise of water level, and vice versa. The correlation between the water level and the osmotic pressure reduces from the upstream to the downstream , and the reservoir water infiltration is the decisive factor of seepage water pressure variation in the core-wall. The variation pattern of soil pressure coincides well with that of pore water pressure. The adjustment of soil pressure value is jointly induced by water seepage and consolidation, which is mainly influenced by the water level in the upstream. During the reservoir impoundment, the effective stress drops, the percentage of pore water pressure in the soil pressure reaches 100% , and as the reservoir water reaches high level, local hydrau- lic fracture is likely to occur. Summarizing the regularity of seepage pressure and soil pressure variation in the grav-el soil core wall during the impoundment can provide reference for similar projects.