过水土石围堰下游护坡的溢流设计风险率模型

系统分析河道来流和泄水建筑物结构尺寸的不确定性与过水围堰运行时下游护坡流速水头和设计抗冲流速水头不确定性之间的关系,以及影响围堰下游护坡安全运行的因素。在土石过水围堰最不利流量的分析方法基础上,提出了用围堰下游护坡的流速水头超过设计条件下最不利溢流工况所对应的抗冲流速水头的概率来刻划溢流工况设计风险率。运用可靠性理论的JC法,给出了过水围堰溢流时设计风险率的计算方法,为堰体下游护坡结构及消能防冲设计提供了理论依据。

A design risk model for the downstream slope for overtopped rockfill cofferdam during flood

The paper systematically discusses the relations of uncretainty between the current velocity head,design head of erosion protection of the downstream slope blocks,construction flood and sizes of diversion structure during operation of rockfill cofferdam,and analyzes the operational safety affecting cofferdam slopes.Based on the computational method for the worst flood discharge during overtopped rockfill cofferdam,a design overflow risk is measured by the probability that current velocity head of cofferdam downstream slope blacks exceeds its design erosion protection head.A computational method for design risk in overflow period of cofferdam is given by using the JC method of reliability theory,providing a theoretical rule of structural design,energy dissipation and erosion protection for overtopped rockfill cofferdam.