Impacts of Bridge Piers on Scour at Downstream River Training Structures: Submerged Weir as an Example
Impacts of Bridge Piers on Scour at Downstream River Training Structures: Submerged Weir as an Example
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DOI：
10.1029/2019wr026720
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发表时间：
2020-04
影响因子：
5.4
通讯作者：
Lu Wang;B. Melville;A. Shamseldin;Ruihua Nie
中科院分区：
文献类型：
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作者：
Lu Wang;B. Melville;A. Shamseldin;Ruihua Nie
河道整治工程通常用于改善河流稳定性和生态条件，并保护上游基础设施免受冲刷和侵蚀。淹没堰是一种典型的河道整治建筑物，通常建在桥梁下游，用于控制坡度。溢流堰可能会造成局部冲刷，破坏结构和受控制河段的稳定。因此，准确地估计冲刷和了解上游桥墩对淹没堰局部冲刷的影响对于安全设计非常重要。本研究描述了一个淹没堰与上游桥墩的冲刷过程的实验，改变两者之间的距离L。在这项研究中，使用中值粒径d50 = 0.85 mm的均匀粗砂在沉积物再循环水槽中进行了56次实验。对于清水冲刷，实验表明，桥墩冲刷过程引起的底形在淹没堰上游产生冲填过程;上游桥墩也可以通过两种机制影响淹没堰下游的冲刷：（i）上游泥沙补充和（ii）流动截面收缩。机制（i）和（ii）可分别减少和增加淹没堰下游清水冲刷深度。对于活床冲刷，上游桥墩可分别减少和增加淹没堰上游和下游的冲刷深度。根据试验数据，分析了淹没堰处冲刷深度与L的关系。
River training structures are conventionally used to improve river stability and ecological conditions and to protect the upstream instream infrastructures from scour and erosion. A submerged weir is a typical river training structure usually built downstream of bridges for grade control. Flow over the weir can cause local scour, destabilizing both the structure and the trained river reach. It is therefore important for safe design to estimate the scour accurately and understand the effects of an upstream bridge pier on local scour at submerged weirs. This study describes experiments on the scour process at a submerged weir with an upstream bridge pier, varying the distance L between the two. In this study, 56 experiments were conducted using uniform coarse sand with a median grain size d50 = 0.85 mm in a sediment‐recirculating flume. For clear‐water scour, the experiments showed that the bedform induced by the pier scour process creates a scour‐and‐fill process upstream of the submerged weir; and the upstream pier can also affect the scour downstream of the submerged weir, through two mechanisms: (i) upstream sediment replenishment and (ii) flow section constriction. The mechanisms (i) and (ii) can reduce and increase the downstream clear‐water scour depth at the submerged weir, respectively. For live‐bed scour, a pier upstream can reduce and increase the scour depth upstream and downstream of the submerged weir, respectively. Based on the experimental data, the dependence of the scour depth at the submerged weir on L is evaluated.