比邻梯级水电站同期建设条件下,若上游水电站围堰遭遇超标洪水发生漫顶溃决,将严重威胁下游水电站施工中期度汛的安全,因此,对度汛水位变化过程进行数值模拟具有重要意义。基于水动力学理论方法,建立了上游水电站围堰漫顶溃决条件下中期度汛水位变化过程模拟的数学模型,并将该模型应用于大渡河流域某相邻梯级水电工程实例中。通过不同计算方案的数值模拟分析,结果表明:该模型及方法是可行的、有效的;相比于基于天然洪水流量的计算方法,所提方法更加贴近工程实际,且度汛最高水位明显增大,因而更有利于工程安全。研究成果为上游水电站围堰挡水条件下的施工中期度汛方案决策及防洪应急预案的制定提供了重要的理论依据。

Simulating the flood level at downstream cascaded hydropower station in mid-stage construction is of critical significance once the adjacent upstream cofferdam in simultaneous construction encounters standard-exceeding flood and overtopping failure which severely threatens the construction safety of the downstream plant. In line with the hydrodynamic theory, a mathematical model is built for simulating the process of water level variation in mid-stage construction period under the condition of cofferdam break of the upstream cofferdam. The model is applied to two adjacent cascade hydropower stations in Dadu River valley. Simulation results suggest that the model is feasible and effective. Compared with the calculation method based on natural flood flow, the proposed method is closer to the actual situation, and the obtained maximum water level in flood season is apparently larger, which is more conducive to the safety of the project. This study provides an important theoretical basis for the decision-making and flood emergency planning of downstream plant in mid-stage construction with cofferdam in the upstream.