SGER: Understanding the mechanics of particle motion in levee-breach closure

了解堤防决口中颗粒运动的力学。卡特里娜飓风过后，哈尼夫·乔杜里和艾哈迈德·卡塞布拉斯特拉特的几个堤坝被冲垮，淹没了新奥尔良市的大部分地区。使用重达1万磅的沙袋，并用直升机运送，试图堵住第17街运河上最关键的堤口，但没有成功。由于可获得的封堵漏洞的信息有限，必须使用反复试验的程序，这导致封堵时间较长，并导致大范围的洪水泛滥。与此相比，已经进行了大量的围堰截流的室内和现场调查，以便改道修筑堤坝，这些研究中提出的几个概念可以扩展到截堤。围堰研究是基于对倾倒材料运动的目视观察，可以利用目前可用的先进数字颗粒跟踪速度计(DPTV)技术来改进这一点，这些技术允许可靠和准确地测量颗粒运动，这对于理解过程的机理至关重要。例如，最近在我们的水力学实验室利用内部资金建造的1：50比例的第17街运河决口物理模型的初步试验表明，沙袋关闭裂口的位置稍有变化就会显著影响其运动。在拟议的研究中，我们将探索DPTV技术在了解颗粒运动机理方面的适用性，推广围堰封堵堤口的方法，并开发确定最佳颗粒尺寸的新方法。预期的结果包括为DPTV开发一种算法，以可视化倾倒材料的运动，并了解颗粒运动的力学，以确定堤坝截流材料的最小尺寸。这项研究的结果为今后制定系统的最佳堤防决口封闭程序的研究奠定了基础。尽管新奥尔良最近堤坝坍塌的原因正在多家机构进行调查，但据我们所知，没有人在调查同样重要的堤坝封堵任务。这项研究的目的是启动初步研究，以便将封堵裂缝和洪水的时间和成本降至最低。这项拟议的研究是探索性的，因为它代表了“对未经检验的想法的初步工作”。不同的DPTV技术在文献中是可用的，并且已经在几个其他应用中使用。这些技术还没有被用来可视化倾倒材料的运动和裂缝闭合的演变。需要这些初步数据来准备一份全面研究堤防关闭的全面建议。这项研究的更广泛影响包括一名研究生和两名本科生的参与，特别是来自代表性不足群体的参与。此外，随着这些研究的进展，将与比利时天主教大学和瑞士联邦理工学院交流信息，在那里对大坝和堤坝决口进行了广泛的调查，并出版了同行评议的期刊出版物，以便普遍传播结果。

Understanding the mechanics of particle motion in levee breach closureM. Hanif Chaudhry and Ahmed KassemABSTRACTSeveral levees were breached following hurricane Katrina, inundating most of the city of New Orleans. Attempts to close the most critical levee breach on the 17th Street Canal using sandbags as large as 10,000 pounds and transported by helicopters were unsuccessful. Due to limited available information on breach closure, trial-and-error procedures have to be utilized which result in taking long times for closure and extensive flooding. As compared to this, considerable laboratory and field investigations for the closures of cofferdam have been conducted for river diversion to build dams and several concepts developed in these studies could be extended to levee closure. The cofferdam studies were based on visual observations of the motion of the dumped material which can be improved utilizing presently available advanced digital particle tracking velocimetry (DPTV) techniques that allow reliable and accurate measurements of the particle movements which are critical for the understanding the mechanics of the process. For example, preliminary tests on a 1:50 scale physical model of the 17th Street Canal breach built recently in our hydraulic laboratory utilizing internal funds show that a slight change in the positioning of a sandbag to close the breach dramatically affects its movement. In the proposed research, we will explore the applicability of DPTV techniques for the understanding of the mechanics of particle motion, to extend the cofferdam closure methods for the closure of levee breach and to develop new methodologies for determining the optimum particle size. The expected results include the development of an algorithm for the DPTV to visualize the motion of the dumped material and understanding the mechanics of particle motion for determining the minimum size of the material for levee closure. The findings of this research represent a base for future research on developing systematic optimum procedures for the closure of levee breaches. Although the causes of the recent levee failure in New Orleans are being investigated at a number of institutions, to the best of our knowledge, no investigations are in progress for an equally important task for the breach closure. The objective of this study is to initiate preliminary research so that the time and costs of breach closure and flooding are minimized. The proposed research is exploratory in nature as it represents "preliminary work on untested ideas". Different DPTV techniques are available in the literature and have been used in several other applications. These techniques have not been used to visualize the motion of the dumped material and the evolution of breach closure. These preliminary data are needed to prepare a full proposal for a comprehensive study for levee closure. The broader impacts of the study include the participation of one graduate and two undergraduate students, especially from the under-represented groups. In addition, as these studies progress, information will be exchanged with the Catholic University, Belgium and Swiss Federal Institute of Technology, Switzerland, where extensive investigations have been conducted on dam and dyke breaches as well as peer-reviewed journal publications for the universal dissemination of results.