Abstract: The paper introduced the sudden drop of confined water level in the foundation of Liujiaxia Dam and analyzed the change law. Further, it was pointed out that it may caused by crack opening or the connection of crack with seepage passage or the drainage passage. As well, it was advanced that the connection of confined water and fracture water would not be a threat to the dam safety.

Key words: confined water in dam foundation, sudden drop of water level, change law, reason analysis

摘要： 介绍了刘家峡坝基承压水力突降情况，分析了承压水变化规律，揭示了承压水位突降是由于裂隙突然张开或裂隙的某一部位突然与相邻的上部裂隙潜水渗流或排水通道相连通造成的，阐明承压水与裂隙潜水的连通一般对大坝的安全不会构成威胁的观点。

关键词: 坝基承压水, 水位突降, 变化规律, 原因分析