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 (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.
