南水北调中线总干渠桥墩壅水影响分析

Backwater Influence of Bridge Piers in Middle Route of South-to-North Water Transfer Project

桥梁建设多在天然河道进行,当桥墩阻水面积占河道过水面积的比例较小时,可以不考虑桥墩壅水影响。南水北调干渠经常高水位运行,流速低,纵坡缓,桥梁壅水可能造成上游交叉建筑物输水能力降低以及渠顶超高不足和安全度的降低等问题。现以某跨渠高速公路桥为例,以数值模拟为手段对桥墩的壅水影响进行分析,认为在缓纵坡渠道上桥墩壅水上游影响长度较大,如跨渠桥梁间距过小,可能引起连锁壅水。桥梁设计时应尽量减小桥墩数量并避免斜交。

There almost have no backwater influence when bridge constructed in the natural river course as the bridge pier anti-water area occupies the river is small. The main channel of the Middle Line of South-to-North Water Transfer Project usually run on high water mark, the speed of flow is low with gentle slope, the bridge backwater possibly reduce the flow caPacity, causing the water overlapping and decrease the safety of ditch. This paper takes the Qing-hong highway bridge as an example, calculates the backwater by numerical simulation, illustrates that the bridge pier backwater affects the length to upstream larger in gentle slope, if the cross ditch bridge spacing excessively is small, which may cause the chain-ike backwater. In the design of the bridge the numbers of bridge pier should reduce and oblique interconnection should avoid.