RAPID: Integrated Geotechnical and Geophysical Investigation of Subaqueous Foundations, Levees and River Banks Impacted by Hurricane Harvey

2017年秋季，飓风哈维造成了严重的风力破坏和洪水。事实上，相关的洪水可以被归类为5000年一次的事件。与洪水相关，发生了重大的沉积物迁移过程。淹没结构和基础周围的沉积物侵蚀，通常被称为冲刷，对基础设施的稳定性构成重大风险。在飓风“哈维”期间，早期的侦察小组观察到桥墩、河堤、板桩墙、巨石墙和其他淹没地基的基础设施受到了严重的冲刷和侵蚀。然而，由于水位仍然升高，安全因素限制了现场调查。事后冲刷和侵蚀研究的一个问题是冲刷孔的再填充。这意味着，当水位和流速下降时，悬浮物运输的沉积物沉降并填充冲刷孔，常常导致对事件期间侵蚀程度的错误评估。此外，填充物是新沉积的，通常很脆弱，可能会给人一种稳定的错觉。该合同将支持收集易腐烂的现场数据，调查冲刷和侵蚀，以及飓风哈维期间受洪水和风暴潮影响的地区的灾后填充物。收集的数据将促进对极端洪水事件期间冲刷、侵蚀和填充物的理解，因此，直接有助于改进风险评估。研究小组将访问在哈维飓风期间遭受严重冲刷和侵蚀的地点，这些地点最初是由早期的侦察小组调查的。将采用综合岩土工程和地球物理方法来收集冲刷和侵蚀的独特数据集，并随后进行填充。海底回声测深仪（啁啾声纳）将对水下沉积物地层进行剖面分析，并由便携式自由落体穿透仪部署提供不同沉积层的岩土参数。侧扫声纳和摄影测量将提供详细的图像和地形。现场可蚀性将使用内聚强度计进行测试。重力取心将在淹没区域进行沉积物取样，而推管取样将在浮出的河岸进行。泥沙样品将被测试岩土泥沙特征和可蚀性。后一项测试将使用侵蚀水槽装置进行。收集到的现场数据将是独一无二的，因为它提供了来自原生沉积物和填充物的岩土技术信息，并将使未来的研究和洞察与哈维飓风等极端洪水事件相关的侵蚀和填充物过程。通过Designsafe-CI数据存储库收集后，这些数据将立即提供给公众和其他研究人员。

Hurricane Harvey caused severe wind damages and flooding in Fall, 2017. In fact, the associated flooding can be classified as a 5,000 year event. Associated to the flooding, significant sediment relocation processes occurred. Sediment erosion around submerged structures and foundations, commonly referred to as scour, represents a significant risk to the stability of infrastructures. During Hurricane Harvey, early reconnaissance teams observed significant scour and erosion at bridge piers, river embankments, sheet pile walls, boulder walls, and other infrastructure with submerged foundations. However, safety constraints limited on site investigations while water levels were still elevated. An issue of post-event scour and erosion investigations is the refilling of scour holes. This means that when with receding water levels and flow velocities, sediment transported in suspensions settles and infills the scour holes, often leading to false assessments of the magnitude of erosion during the event. Additionally, the infill is freshly deposited and often weak, potentially providing a false image of stability. This award will support the collection of perishable field data investigating scour and erosion, as well as post-event infill at locations impacted by flooding and storm surge during Hurricane Harvey. The collected data will advance the understanding of scour, erosion, and infill during extreme flooding events, and therefore, contribute directly to the improvement of risk assessment.The research team will visit sites that experienced severe scour and erosion during Hurricane Harvey, and that were initially investigated by early reconnaissance teams. An integrated geotechnical and geophysical approach will be employed to gather a unique data set of scour and erosion, and the subsequent infilling. Sub-bottom echo sounders (chirp sonar) will profile the submerged sediment stratigraphy, supported by portable free fall penetrometer deployments which will provide geotechnical parameters of the different sediment layers. Side scan sonar and photogrammetry will provide detailed imagery and topography. In-situ erodibility will be tested using a cohesive strength meter. Gravity coring will enable sediment sampling in submerged areas, while push tube sampling will be conducted at emerged banks. Sediment samples will be tested for geotechnical sediment characteristics, and erodibility. The latter tests will be conducted using a Erosion Flume Apparatus. The collected field data will be unique by providing geotechnical information from the native sediments and the infill, and will enable future research and insights into the erosion and infill processes associated to extreme flooding events as during Hurricane Harvey. The data will be made available to the public and other researchers immediately after collection through the Designsafe-CI data repository.