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

堤防决口闭合中粒子运动的机理研究。卡特里娜飓风过后，几处堤坝被冲毁，淹没了新奥尔良市的大部分地区。试图使用重达1万磅的沙袋并由直升机运输来封闭17街运河最关键的决口，但没有成功。由于现有的关于关闭裂口的资料有限，必须采用试错程序，结果需要很长时间才能关闭和广泛的水浸。与此相比，已经进行了大量的实验室和实地调查，对围堰的关闭进行了引水筑坝，并且在这些研究中发展的一些概念可以扩展到堤防关闭。围堰研究是基于对倾倒材料运动的视觉观察，可以利用目前可用的先进数字粒子跟踪测速（DPTV）技术进行改进，该技术可以对粒子运动进行可靠和准确的测量，这对于理解该过程的力学至关重要。例如，我们最近在水力实验室利用内部资金对17街运河决口的1:50比例物理模型进行了初步测试，结果表明，封闭决口的沙袋位置的轻微变化会极大地影响其运动。在本研究中，我们将探索DPTV技术在理解颗粒运动力学方面的适用性，扩展围堰封堵堤坝决口的方法，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，以确定筑堤材料的最小尺寸。本研究结果为未来研究开发系统的最佳堤防决口封闭程序奠定了基础。尽管一些机构正在调查最近新奥尔良大堤溃坝的原因，但据我们所知，没有针对同样重要的关闭决口的任务进行调查。本研究的目的是开展初步研究，以便将缺口关闭和洪水的时间和成本降至最低。拟议中的研究本质上是探索性的，因为它代表了“未经检验的想法的初步工作”。文献中提供了不同的DPTV技术，并已在其他几个应用中使用。这些技术还没有被用来可视化倾倒物质的运动和缺口闭合的演变。这些初步数据需要准备一份完整的建议，以进行全面的堤防关闭研究。这项研究的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的群体。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换资料，这两所大学已对水坝和堤防决口进行了广泛调查，并将与同行审查的期刊出版物交换资料，以便普遍传播研究结果。

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.