实用堰后接梯形断面泄槽水面线计算方法探讨

梯形断面是泄槽最常用的断面形式之一，泄槽水面线计算对溢洪道设计具有重要意义。实用堰后接梯形断面泄槽起始水深及水面线计算须求解非常复杂的非线性方程，传统试算法计算过程繁琐，需要多次计算才能得到满足精度要求的结果。为解决实用堰后接梯形断面泄槽水面线计算的难题，构造坡降差方程，介绍了弦截法计算泄槽水面线的具体步骤，并对起始水深方程进行恒等变形，得出了起始水深的直接计算公式。实例表明，采用的计算方法可行，计算结果可靠，可为类似工程设计提供参考。

Discussion on the calculation method of water surface profile in trapezoidal section spillway after practical weir

Trapezoidal section was one of the most commonly used cross-sectional forms for spillways, and the calculation of water surface profile in spillway was of great significance for the design of spillways. The calculation of the starting water depth and water surface profile in the trapezoidal section spillway after the practical weir required solving complex nonlinear equations, and the traditional trial-and-error method was cumbersome and required multiple calculations to obtain results that meet the accuracy requirements. To solve the problem of calculating the water surface profile in the trapezoidal section spillway after the practical weir, a slope difference equation was constructed and the specific steps of the chord intercept method for calculating the spillway water surface profile were introduced. The starting water depth equation was transformed into an equivalent form, and a direct formula for calculating the starting water depth was derived. Examples showed that the calculation method was feasible and the results were reliable, and could provide reference for similar engineering designs.