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本文提出了考虑弦高以及流速和尺寸限制的U型渠道设计的最优条件。弦高可以设计流量为基础确定或作为水深的函数,这样更具普遍性。分析结果表明,最佳水力断面的边坡参数为0.514,并非有关U型渠道文献中所述的0.7.上述水力学分析使最优渠道断面窄而深.当衬砌成本与开挖成本比值大时,使开挖和衬砌成本之和最低的数学分析则偏爱稍宽的渠道.本文解析阐述了使成本最低的必要条件。结果表明,0.514的最优边坡参数设定了一个上界,且意味着在给定流量下最优U型断面不可能比经典最佳水力断面宽.文中还提供了设计辅助用表.
This paper presents the optimal design of a U-shaped channel considering the chord height, flow rate and size constraints. The chord height can be determined based on the design flow or as a function of water depth, which is more general. The results show that the slope parameters of the optimal hydraulic section are 0.514, which is not the same as the 0.7 described in the U-shaped channel literature.The above hydraulic analysis makes the optimal channel section narrow and deep.When the ratio of lining cost to excavation cost is large , The mathematical analysis that minimizes the sum of excavation and lining costs favors a slightly wider channel.This paper analyzes the necessary conditions to minimize costs. The results show that the optimal slope parameter of 0.514 sets an upper bound, and means that the optimal U-shaped cross section can not be wider than the classical optimal hydraulic cross section at a given flow rate.