南水北调中线干渠桥墩壅水计算公式的选择

南水北调中线工程沿线布置数百座桥梁,桥墩壅水对渠道的过流能力和渠道的水面线具有一定的影响,因此,准确计算桥墩壅水对于水面线的计算和输水渠道的设计具有十分重要的作用。以典型的圆柱型桥墩为研究对象,采用VOF方法对桥墩周围的紊流场进行了数值模拟,并计算了给定水深、流量和桥墩阻水比等条件下桥墩的壅水大小,通过与一维经验公式计算结果的对比,建议选择无坎宽顶堰公式作为桥墩壅水计算公式。最后,在南水北调中线干线一维数值仿真平台上分析了所有桥梁的壅水效应对渠首水位的影响。

Formula Selection on Backwater Effects of Bridge Piers for the Middle Route of South-to-North Water Transfer Project

Investigation of how piers influence channel obstruction and hydraufic efficiency is an important issue, for it can influence the designed water level during the period of project design and the water capacity during the period of project running. This research focused on the circular piers, the 3D flow field computer numerical simulation was used to analyze the water level increased by the piers under the different water depth, flow rate and ratio of the area of the submerged part of the piers to the total flow area. As a result, the formula of broad-crest ridge-free weir can be applied to calculate the increased water level by the piers, At last, the influence of cumulative water head loss by all bridges on water level of canal head was studied through 1D numerical simulation in middle route of South-to-north water transfer project.