Abstract: Dahua hydropower station has been in operation for more than 30 years. For the 9 gravity dam blocks on the left bank, the uplift pressure of dam foundation is much higher than designed value. By analysis on monitoring data, the conclusion is gotten that the high uplift pressure is caused by water level downstream and underground water. After the second stage construction, the uplift pressure was decreased first and then increased. Combined with the actual project condition, the influence of underground water on uplift pressure, by seepage through dam toe foundation and downstream of the dam, is analyzed. The cause reasons for high uplift pressure are presented, as well as the prevention suggestions.

Key words: left gravity dam, uplift pressure, analysis

摘要： 大化水电站运行30余年来，左岸重力坝全部9个坝段的基础扬压系数普遍偏大，远超过大坝荷载设计采用的渗透压力折减系数。历次大坝观测资料分析指出，扬压水位偏高主要受下游水位及地下水的影响。二期工程施工期间，开挖了与其相邻的接头土坝，且不存在岸坡地形，投产以后多数坝段扬压水位呈现明显“先降后升”现象，根据历次观测资料分析结论调查分析，结合左岸重力坝下游侧设计加固的挡土墙和接头土石坝形成三面合围土体的实际情况，进一步分析土体内地下水从坝趾基础和下游侧渗透对坝基扬压水位的作用机理，指出扬压水位普遍偏高的直接原因，并提出防范建议。

关键词: 左岸重力坝, 扬压水位, 分析