THE INFLUENCE OF PIER GEOMETRY AND DEBRIS
THE INFLUENCE OF PIER GEOMETRY AND DEBRIS
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桥墩几何形状和碎片的影响
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Gustavo A. M. de Almeida
中科院分区：
文献类型：
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作者：
D. Panici;Gustavo A. M. de Almeida
8本文分析了桥墩的几何形状和提供的9块碎片的几何形状对桥墩木屑堵塞形成和生长的影响。共进行了162 10项实验室实验。实验结果表明，由圆柱形碎片堆积形成的碎片堵塞（即木钉）的最大尺寸小于由不规则形状的天然无枝木材形成的碎片堵塞。此外，有分枝的岩屑实验13产生的堵塞比无分枝的天然岩屑实验13产生的堵塞要小得多，稳定性也差得多。最后，对6种不同桥墩形状的实验进行了比较，结果表明桥墩形状对木屑淤塞最大尺寸的影响可以忽略不计。唯一的例外是方形桥墩，它显示的碎片堵塞尺寸比其他类型的桥墩略大。在流动河床上的桥墩长期以来一直是水利和结构工程师关注的对象。桥墩施加的阻力减小了桥墩的流过面积，改变了桥墩周围的流场，产生了回水效应和局部冲刷。在过去的几十年里，这些问题已经得到了广泛的研究（例如Melville和Sutherland, 1988; Dargahi, 1990; Williamson, 1996； Johnson和King, 2003； Dey和Raikar， 2007），并且已经开发了许多模型24来帮助评估洪水风险和设计弹性墩基础。在许多河流中，洪水期间大量木质碎屑（以下简称LWD）的积累会严重加剧上述影响。先前的研究表明，碎屑淤塞可以显著减小流道面积（Parola et al., 2000; Daniels and Rhoads, 2004; Bradley et al., 2005; 28 Pfister et al., 2013），从而强烈影响流道内的流速和湍流分布（Gurnell et al., 2002; Daniels and Rhoads, 2004; Wilcox and Wohl, 2006; Manners et al., 3）
8 This paper analyses the influence of the geometry of bridge piers and the geometry of the 9 supplied debris on the formation and growth of wood debris jams at bridge piers. A total of 162 10 laboratory experiments have been conducted. Experimental results showed that the maximum size 11 of debris jams formed by the accumulation of cylindrical debris (i.e. wooden dowels) is smaller 12 than that of jams formed by natural non-branched wood of irregular shape. In addition, experiments 13 with branched debris resulted in jams that were significantly smaller and less stable than those with 14 non-branched natural debris. Finally, comparison of experiments conducted with six different pier 15 shapes indicate that the shape of a pier has negligible effects on the maximum size of a woody 16 debris jam. The only exception to this observation was for square piers, which showed slightly 17 larger debris jam sizes than the other types of piers tested. 18 INTRODUCTION 19 Bridges piers resting on mobile river beds have long been the object of concerns among hy20 draulic and structural engineers. The obstruction imposed by the pier reduces the flow area, alters 21 the flow field around the pier, and produces backwater effects and localised scour. These problems 22 1 Panici, May 23, 2019 have been extensively studied over the last decades (e.g. Melville and Sutherland, 1988; Dargahi, 23 1990; Williamson, 1996; Johnson and King, 2003; Dey and Raikar, 2007), and numerous models 24 have been developed to aid the assessment of flood risk and the design of resilient pier foundations. 25 In many rivers, the accumulation of large woody debris (hereafter referred to as LWD) during floods 26 can critically exacerbate the above effects. Previous studies have shown that debris jams can signif27 icantly reduce the flow area (Parola et al., 2000; Daniels and Rhoads, 2004; Bradley et al., 2005; 28 Pfister et al., 2013), which strongly affects the distribution of flow velocities and turbulence in the 29 channel (Gurnell et al., 2002; Daniels and Rhoads, 2004; Wilcox and Wohl, 2006; Manners et al., 3