南水北调中线工程输水渠道桥梁影响分析

Effects of bridges on conveyance canal of South-to-North Water Transfer Middle Route Project

采用堰流公式对南水北调中线总干渠中的大量桥梁对渠首水位和水头损失的影响进行模拟计算和分析。计算结果表明,桥梁对渠首水位的影响不能用每座桥梁的水头损失进行简单叠加;在采用阻水能力较小的半圆头尾型桥墩时,设计和加大流量下由764座桥梁引起的渠首水位增加分别仅为0.194 m和0.238 m。通过对所有桥梁水头损失的计算比较发现,不同的桥墩形状造成的总水头损失相差较大,选用流线型、水流易于通过的桥墩形状可以节约相当部分的水头。

The effects of bridges over the arterial canal on the water level at canal head and water head loss in the South-to-Noah Water Transfer Middle Route Project were calculated and analyzed by use of the weir formula. The result shows that the effects of bridges on the water level at canal head cannot be derived only by the simple addition of water head loss of each bridge, and that the rises of water level induced by 764 bridges under designed discharge and increased discharge were only 0.194m and 0.238 m when the semi-circular bridge piers with low water-resisting ability were adopted. The comparative analysis shows that there are great differences between the water head losses of bridges with different shapes of piers, and that the adoption of stream-fined piers easy for water flow to pass through may help to save considerable water head.