SGER/Collaborative Research: 2008 Midwest Levee Failure Invesigation

SGER/合作研究：2008 年中西部堤坝溃决调查

• 批准号: 0842374
• 负责人: Jean-Louis Briaud
• 金额: $ 5.53万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0842374&HistoricalAwards=false
• 关键词: SGER; Collaborative; Research; 2008; Midwest

This Small Grant for Experimental Research (SGER) award is an immediate field reconnaissance and data collection effort to collect sensitive and time-dependent perishable levee performance (failures and successes) data, documenting the performance of the flood protection levees along the Mississippi River between Davenport Iowa and St. Louis Missouri during the June and July 2008 storms. The objective of the study is to perform an integrated evaluation of levee performance subject to "extreme" loading, such as extended duration elevated river stages (inducing underseepage/internal erosion) and overtopping/scour erosion. Individual erosion characteristics for levee performance have been studied and significantly advanced in the last ten years, but no integrated studies have been performed that synthesize all the erosion characteristics in one model. This study provides desperately needed comprehensive field data to validate empirical formulas and numerical models that have been developed to analyze erosion of levees. There are lessons of potentially vital importance to be learned from the performance of the Midwest levee systems. The data collection consists of detailed laser imaging surveys (Terrestrial LiDAR) of the breach and erosion/scour features, characterization of the vegetative grass cover, characterization of the levee soil materials (Unified Soil Classification System, Atterberg Limits, density, grain-size distribution, and Erosion Function Apparatus rating), documentation of river stage at the location of levee failures from eyewitness accounts as well as river stage gaging stations, and lessons from the engineers and personnel who observed the levee failures and performed/oversaw repairs. Thus, this study provides comprehensive field data for use in advancement of levee erosion-resistance design. There are thousands of miles of earthen levees in the United States, many without any engineering design or certification, that are supposed to provide flood protection for residents living within the protected zone behind the levees. Of the levees that were designed in accordance with accepted engineering methods, very few of the levees have been designed to resist the most common failure type, overtopping. Thus, the results of this field reconnaissance study can be directly applied to the entire U.S. flood protection system to evaluate the reliability of earthen levees as flood protection elements, as well as recommendations for levee improvements to increase performance reliability.

这项实验研究小额拨款(SGER)奖是一项即时的实地勘察和数据收集工作，旨在收集敏感的和随时间变化的易腐烂堤防性能(失败和成功)数据，记录2008年6月至7月风暴期间爱荷华州达文波特和密苏里州圣路易斯之间密西西比河沿岸防洪堤坝的性能。这项研究的目的是对堤防在“极端”荷载作用下的性能进行综合评估，如延长持续时间的高架河段(导致潜流/内部侵蚀)和溢流/冲刷侵蚀。在过去的十年里，人们对堤防性能的单个侵蚀特性进行了研究，并取得了显著的进展，但还没有进行将所有侵蚀特性综合在一个模型中的综合研究。这项研究提供了急需的全面现场数据，以验证已开发的用于分析堤防侵蚀的经验公式和数值模型。从中西部堤防系统的表现中可以学到一些可能至关重要的经验教训。数据收集包括详细的激光成像测量(陆地激光成像测量)，有关决口和侵蚀/冲刷特征的调查；植被覆盖的特征；堤防土壤材料的特征(统一的土壤分类系统、Atterberg界限、密度、粒度分布和侵蚀功能仪器评级)；目击者帐户以及河流水位计量站提供的堤防损毁位置的河流资料；以及观察堤防破坏和实施/监督修复工作的工程师和人员取得的经验教训。因此，本研究为推进堤防抗冲刷设计提供了全面的现场资料。美国有数千英里长的土堤，其中许多没有任何工程设计或认证，它们本应为居住在堤坝后面保护区内的居民提供防洪保护。在按照公认的工程方法设计的堤防中，很少有堤防被设计成抵抗最常见的破坏类型--漫顶。因此，这项现场勘察研究的结果可以直接应用于整个美国防洪系统，以评估土堤作为防洪要素的可靠性，并提出改进堤防以提高性能可靠性的建议。