{"title":"Effect of submergence of sacrificial piles on local scour reduction at a bridge pier under U-type debris jam conditions","authors":"","doi":"10.1016/j.jher.2024.10.003","DOIUrl":null,"url":null,"abstract":"<div><div>A group of non-submerged sacrificial piles placed in front of a bridge pier have a propensity to trap a significant volume of floating debris during river floods, which affects their effectiveness as a scour countermeasure. This problem can be avoided by using short piles such that the tips of the piles lie below the free water surface, also known as submerged piles. However, it will cause the floating debris to accumulate at the pier itself. The current study attempts to ascertain whether or not such trapping of debris with submerged piles is preferable to that by emergent piles from the perspective of local scour protection of the bridge pier. Laboratory flume tests were conducted under uniform, subcritical, steady, and clear-water flow conditions. The ideal submergence value was ascertained by examining submerged sacrificial piles with varying spans (or lengths) with respect to the flow depth. The local scour reduction efficacy of these submerged piles was then compared with non-submerged piles, first without and subsequently with U-type (horseshoe-shaped) debris jams. Results revealed that submerged sacrificial piles spanning 50–60 % of the flow depth provide optimum protection to the pier against local scour, and this was slightly higher than that offered by emergent piles in an identical layout. In addition, submerged sacrificial piles with ideal submergence protected the pier better against local scour than emergent piles under U-type debris jam conditions.</div></div>","PeriodicalId":49303,"journal":{"name":"Journal of Hydro-environment Research","volume":null,"pages":null},"PeriodicalIF":2.4000,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Hydro-environment Research","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1570644324000558","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
A group of non-submerged sacrificial piles placed in front of a bridge pier have a propensity to trap a significant volume of floating debris during river floods, which affects their effectiveness as a scour countermeasure. This problem can be avoided by using short piles such that the tips of the piles lie below the free water surface, also known as submerged piles. However, it will cause the floating debris to accumulate at the pier itself. The current study attempts to ascertain whether or not such trapping of debris with submerged piles is preferable to that by emergent piles from the perspective of local scour protection of the bridge pier. Laboratory flume tests were conducted under uniform, subcritical, steady, and clear-water flow conditions. The ideal submergence value was ascertained by examining submerged sacrificial piles with varying spans (or lengths) with respect to the flow depth. The local scour reduction efficacy of these submerged piles was then compared with non-submerged piles, first without and subsequently with U-type (horseshoe-shaped) debris jams. Results revealed that submerged sacrificial piles spanning 50–60 % of the flow depth provide optimum protection to the pier against local scour, and this was slightly higher than that offered by emergent piles in an identical layout. In addition, submerged sacrificial piles with ideal submergence protected the pier better against local scour than emergent piles under U-type debris jam conditions.
放置在桥墩前的一组非沉没式牺牲桩在河水泛滥时容易吸附大量漂浮物,从而影响其作为冲刷对策的效果。使用短桩(也称为沉桩)可避免这一问题,即桩尖位于自由水面以下。不过,这会导致漂浮物在码头本身堆积。目前的研究试图从桥墩局部冲刷保护的角度,确定沉没桩对碎石的这种截留是否优于浮出桩。实验室水槽试验是在均匀、亚临界、稳定和清水流动条件下进行的。通过检测与水流深度相关的不同跨度(或长度)的沉没牺牲桩,确定了理想的沉没值。然后,将这些沉没桩与非沉没桩(先是无沉没桩,后是 U 型(马蹄形)碎石坝)的局部冲刷减少效果进行比较。结果表明,沉入水下的牺牲桩占水流深度的 50-60%,可为码头提供最佳保护,防止局部冲刷,其效果略高于相同布局下的浮出桩。此外,在 U 型泥石流堵塞条件下,具有理想沉没度的沉没式牺牲桩比冒出式桩能更好地保护码头免受局部冲刷。
期刊介绍:
The journal aims to provide an international platform for the dissemination of research and engineering applications related to water and hydraulic problems in the Asia-Pacific region. The journal provides a wide distribution at affordable subscription rate, as well as a rapid reviewing and publication time. The journal particularly encourages papers from young researchers.
Papers that require extensive language editing, qualify for editorial assistance with American Journal Experts, a Language Editing Company that Elsevier recommends. Authors submitting to this journal are entitled to a 10% discount.