三峡工程二期围堰截流度汛期的水力学计算

三峡工程二期施工围左岸，进行主河床截流，迫使江水从右岸导流明渠下泄，为减小截流强度，满足明渠通航要求，围堰在１９９７年汛前进行了预进占和垫底平抛，预留４６０ｍ宽的口门度汛，在汛期各级流量与不同口门宽度条件下，对导流明渠分流比，非龙口段线堤口门的流速，落差等水力学要素进行了分析计算，并进行了实时校验，计算成果与实测值吻合较好。

Hydraulic calculation for TGP second stage cofferdam construction during flood period and its actual verification

The Stage II Three Gorges Project is constructed by enclosing left channel of Yangtze river. The main river channel closure forces the river flow to pass through the open diversion channel. In order to decrease the river closure intensity and meet navigation requirement of the open diversion channel, the construction of the pilot dykes for cofferdam and the horizontal bedding of the deep channel had started in advance before the 1997 high water period, with a 460-m wide opening unclosed for flood passing in 1997. Hydraulic elements of flow division ratio of the open diversion channel, velocity, head difference, etc., at the opening formed by pilot dykes were analysed, calculated and checked in real time for various discharges and opening widths in the high water period. Calculated results are in good agreement with observed ones.