摘要
为优化跨度不等并行桥梁的设计,降低桥孔布置方式对防洪及桥下净空的不利影响,利用明渠水槽开展概化模型试验,研究了并行桥梁的多种跨径组合及布置方式对桥前壅水的影响规律,并基于量纲分析方法研究了影响并行桥桥前最大壅水高度的主要因素。结果表明:桥前壅水高度沿桥梁上游方向先增大后减小或单调减小;当并行桥梁之间的跨径比小于2时,宜将大跨径桥梁布置于上游,而当跨径比大于等于2时,宜将小跨径桥布置于上游,有利于减少壅水高度;对于跨径比不为整数的并行桥梁,将大跨径桥和小跨径桥的一组桥墩沿流向共线布置时的壅水高度小于将两桥桥孔沿河道中心对称布置;并行桥的桥前最大壅水高度受明渠流流态影响较大,随弗劳德数的增大近似呈线性增加,同时,最大壅水高度还随着相对水深和阻水比的增加而变大;并行桥阻水比对壅水的影响机制与单一桥梁有差异,当下游桥墩位于上游桥墩的尾流区时,下游桥墩产生的附加阻水效应极小,因此,并行桥阻水比的计算应考虑上游桥墩对下游桥墩的遮蔽效应。最后,根据试验数据和前人多桥壅水高度研究成果,提出了通过叠加上下游桥梁各自壅水高度计算跨度不等并行桥最大壅水高度的计算方法。
In order to optimize the design of parallel bridges with unequal spans and reduce the adverse effects of bridge opening arrangement on flood control and clearance under the bridge,a generalized model experiment is conducted by using an open channel flume to study the influence of various span combinations and arrangement methods of parallel bridges on the backwater in front of the bridge.The main factors affecting the maximum backwater height in front of the parallel bridge are studied based on dimensional analysis method.The result shows that(1)the height of the backwater in front of the bridge first increases and then decreases or monotonically decreases along the upstream direction of the bridge;(2)when the span ratio between parallel bridges is less than 2,it is advisable to arrange large span bridges upstream,while when the span ratio is greater than or equal to 2,small span bridges should be arranged upstream to reduce the height of backwater;(3)for parallel bridges with non integer span ratios,the backwater height when a group of piers of large and small span bridges are arranged along the same line in the flow direction is smaller than when the two bridge openings are symmetrically arranged along the center of the river;(4)the maximum backwater height in front of the parallel bridge is greatly influenced by the flow pattern of the open channel,and increases approximately linearly with the increase of Froude number,and the maximum backwater height also increases with the increase of relative water depth and water resistance ratio at the same time;(5)the mechanism of the influence of parallel bridge water resistance ratio on backwater is different from that of a single bridge,when the downstream bridge pier is located in the wake area of the upstream bridge pier,the additional water resistance effect generated by the downstream bridge pier is minimal,therefore,the calculation of parallel bridge water resistance ratio should consider the shielding effect of the upstream bridge pier on the downstream bridge pier.Finally,based on experimental data and previous study on the backwater height of multiple bridges,a calculation method for calculating the maximum backwater height of parallel bridges with unequal spans by overlaying the respective backwater heights of upstream and downstream bridges is proposed.The study result can provide reference for flood control optimization design of highway bridge expansion projects.
作者
陈猇
陈启刚
张汁
王志华
王振
CHEN Xiao;CHEN Qi-gang;ZHANG Zhi;WANG Zhi-hua;WANG Zhen(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;Qinghai Traffic Engineering Technical Service Center,Xining Qinghai 810000,China)
出处
《公路交通科技》
CSCD
北大核心
2023年第10期116-125,共10页
Journal of Highway and Transportation Research and Development
基金
青海省交通运输厅科技项目(2021-02)
青海省重点研发与转化计划科技成果转化专项项目(2021-SF-161)。
关键词
桥梁工程
壅水
模型试验
并行桥
不同跨度
bridge engineering
backwater
model test
parallel bridges
unequal spans
作者简介
陈猇(1995-),男,湖北宜昌人,硕士.(zgchenxiao822@163.com);通讯作者:陈启刚(1987-),男,四川宜宾人,博士,副教授.(chenqg@bjtu.edu.cn)。
