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灾和洪水。事实上，与之相关的洪灾可以归类为5000年一次的事件。与洪水相关的是，发生了重大的泥沙迁移过程。水下建筑物和基础周围的泥沙侵蚀，通常被称为冲刷，对基础设施的稳定性构成了重大风险。在飓风哈维期间，早期侦察小组观察到桥墩、河堤、板桩墙、巨石墙和其他基础设施的严重冲刷和侵蚀。然而，安全限制仅限于现场勘察，而水位仍处于高位。事后冲刷和侵蚀调查的一个问题是重新填充冲刷坑。这意味着，当水位和流速下降时，以悬浮物形式输送的泥沙会沉降并填满冲刷坑，往往会导致对冲刷过程中侵蚀程度的错误评估。此外，填充物是新沉积的，往往很弱，可能会给人一种稳定的假象。这项奖励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点的灾后填充。收集的数据将促进对极端洪水事件期间冲刷、侵蚀和填充的了解，因此直接有助于改进风险评估。研究小组将访问飓风哈维期间经历严重冲刷和侵蚀的地点，以及早期侦察小组最初调查的地点。将采用一种综合的岩土工程和地球物理方法来收集关于冲刷和侵蚀以及随后的填土的独特数据集。海底回声探测仪(Chirp声纳)将在便携式自由落体透视仪的支持下对水下沉积物地层进行剖面分析，该仪器将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。现场腐蚀性将使用粘结强度计进行测试。重力取心将允许在淹没区域进行沉积物采样，而推管采样将在出现的岸边进行。将对沉积物样本进行岩土沉积物特性和可腐蚀性测试。后一项试验将使用侵蚀水槽装置进行。收集的现场数据将是独一无二的，因为它提供了来自自然沉积物和填充物的岩土信息，并将使未来能够研究和洞察与飓风哈维期间的极端洪水事件相关的侵蚀和充填过程。数据收集后将通过DesignSafe-CI数据库立即向公众和其他研究人员提供。

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.