湖北省碾盘山水利水电枢纽超标准洪水溃堰风险分析

Risk analysis and countermeasures of dambreak due to excessive flood in Nianpanshan water complex in Hubei Province

湖北省碾盘山水利水电枢纽为Ⅱ等大(2)型工程,采取围堰一次拦断河床,施工导流设计标准为全年P=10%。当碾盘山围堰遭遇超标准洪水,可根据水情适时破堰行洪。为预测溃堰对下游的防洪影响,建立了溃坝洪水演进模型,能同时进行上游调洪演算、溃口发展过程模拟和坝下游洪水演算。计算结果表明,上游发生10年一遇洪水、20年一遇洪水溃堰后,溃坝洪水波在传播过程中坦化,不会超过沙洋河段安全泄量。上游发生50年一遇洪水溃堰后,沙洋河段断面将超过安全泄量18400 m^(3)/s,对碾盘山下游汉江防洪产生附加压力。计算结果为碾盘山围堰超标准洪水防御、汉江防洪应急工作提供技术支撑。

Nianpanshan water complex is Class Ⅱ large(2)project,which takes cofferdam to block off the river bed,whose diversion design standard is P=10% for the whole year.When the cofferdam encounters excessive flood,the cofferdam can be broken to discharge flood according to the water situation.To predict the cofferdam break impact on downstream area,the paper establishes a dambreak flood routing model,which can carry upstream flood routing calculation,the breach development process simulation and downstream flood routing simultaneously.The calculation results show that the dam break flood wave will flatten in the process of propagation after the dam break due to the 10-year and the 20-year flood in the upstream,and will not exceed the safe discharge of Shayang reach.The section of Shayang River will exceed the safe discharge of 18400 m^(3)/s when the dam breaks due to the 50-year flood in the upstream,which is a big threat to the downstream area of Hanjiang River.The calculation results provide technical support for the beyond standard flood prevention of Nianpanshan cofferdam and the flood emergency work of Hanjiang River.