Understanding and Quantifying Structural Loading from Tsunami-Induced Debris Fields

海啸和风暴潮对世界各地的沿海社区构成重大威胁。在海啸风险区，大规模沿海淹没的威胁因堆积的大片废墟而加剧，这些废墟会影响关键的基础设施系统并在其周围建立。这些碎石场由各种物体组成，这些物体随着水流的到来而移动，大小不一，从建筑材料到受损的建筑物到车辆和大型船只。为了减少对沿海基础设施的风险和破坏，并最终改善这些风险区社区的福利，有必要改进设计和战略性改造战略，并要求更好地了解与这种碎片撞击相关的力量，特别是与大而杂乱的碎片领域相关的力量。以前的研究讨论了波浪和水流负荷对基础设施的影响，但很少有人研究由这种水流携带的多块碎屑或碎屑场的影响。水流驱动的泥石场本质上是混乱的；几乎相同的初始条件可能会导致截然不同的结果。因此，预测这些事件产生的负荷需要一种统计方法来帮助解决碎片如何与建成环境相互作用和影响的不确定性。利用实验结果和数值模拟相结合的方法，本项目将以一种适用于这种高度非线性、混沌系统的方式来量化冲击力和筑坝效应。这项研究的结果将提供关键信息，以提高沿海地区结构系统的安全性和可持续性，并改进灾后反应和恢复工作。该项目的数据将存档在自然灾害工程研究基础设施(NHERI)数据仓库(https://www.DesignSafe-ci.org).该项目为国家科学基金会在国家减少地震灾害计划中的作用做出了贡献。该项目将结合两个不同的实验项目，一个在俄勒冈州立大学的NHERI大型波浪水槽设施，另一个在华盛顿大学，与一种战略性的数值模拟方法相结合，以预测海啸危险区结构上的碎片诱导力。大量潜在的碎片撞击情景，再加上受大型海浪事件影响的沿海社区碎片区域的不同性质，远远超出了任何单一实验方案的实际范围。因此，开发一种稳健的、可预测的数值方法对于提高对复杂的碎片-流体-结构相互作用现象的理解至关重要。这项研究有三个主要目标：(1)为流动驱动的多碎片撞击情景产生具有统计代表性的实验测试结果，为数值建模工作提供信息；(2)开发、改进和组合一系列能够捕捉与实验结果相关的关键物理现象的复杂数值模型；以及(3)使用基于统计的方法扩展数值模型，以在更广泛的情景下预测碎片诱导力。通过使用统计方法，这项研究将开发出具有物理意义的、具有代表性的对碎片撞击和堰塞力的风险的数字估计，并得到实验结果的支持，这将为工程师和社区官员在海啸和风暴潮易受影响的地区设计安全和有弹性的沿海基础设施提供更好的信心。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Tsunamis and storm surges pose a significant threat to coastal communities around the world. In tsunami risk zones, the threats from large-scale coastal inundation are exacerbated by the accumulation of large debris fields that impact and build up around critical infrastructure systems. These debris fields are composed of various objects that move with the incoming flow and that range in size from construction materials from damaged buildings to vehicles and large watercraft. To lessen the risks and damage to coastal infrastructure and ultimately improve the welfare of communities in these risk zones, improved design and strategic retrofit strategies are necessary and require a better understanding of the forces associated with such debris impacts, specifically forces associated with large, disorganized debris fields. Previous studies have addressed the effect of wave and flow loads on infrastructure, but few have examined the influence of multiple pieces of debris, or debris fields carried by such flows. Flow driven debris fields are fundamentally chaotic in nature; nearly identical initial conditions can lead to widely varying outcomes. Thus, predicting the loads arising from these events requires a statistical approach to help address the uncertainties with how debris interacts with and affects the built environment. Using a combination of experimental results and numerical modeling, this project will quantify the impact forces and damming effects in a manner valid for this kind of highly nonlinear, chaotic system. The results of this research will provide key information to enable improved safety and sustainability of structural systems in coastal regions and to improve post-event response and recovery efforts. Data from this project will be archived in the Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org). This project contributes to NSF's role in the National Earthquake Hazards Reduction Program. This project will combine two distinct experimental programs, one at the NHERI large wave flume facility at Oregon State University and the other at the University of Washington, with a strategic numerical modeling approach to predict debris-induced forces on structures in tsunami hazard zones. The large number of potential debris impact scenarios, combined with the disparate nature of debris fields across coastal communities impacted by large wave events, is well beyond the practical scope of any single experimental program. Thus, the development of a robust, predictive numerical approach is critical to improving the understanding of complex debris-fluid-structure interaction phenomena. This research has three primary objectives: (1) generate statistically representative experimental test results for flow-driven, multi-debris impact scenarios to inform numerical modeling efforts; (2) develop, refine, and combine a series of complex numerical models capable of capturing the key physical phenomena associated with the experimental results; and (3) extend the numerical models using a statistics-based approach to debris-induced force predictions under broader scenarios. By using a statistical approach, this research will develop a physically meaningful, representative numerical estimate of the risks of debris impact and damming forces, supported by experimental results that will provide engineers and community officials with an improved confidence for designing safe and resilient coastal infrastructure in tsunami and storm surge susceptible regions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.