Collaborative Research: Hybrid Flow-Sediment-Structure Interaction Analysis of Extreme Scour due to Coastal Flooding

基础冲刷是沿海社区在洪水灾害中造成结构破坏的主要原因之一。该项目将利用最先进的波浪水槽物理模型、岩土离心模型和数值模拟来回答一些与极端洪水、土壤和结构之间的相互作用有关的关键和开放问题，这些相互作用导致冲刷和基础破坏，从而改变当前对复杂城市环境中洪水诱发冲刷过程中关键物理过程的理解范式。沿海灾害减轻的开源多物理场计算工具的增强将为更广泛的土木和沿海工程研究界提供强大的多学科建模平台。从基础知识的积累中得到的极端冲刷液化的新参数化集将有利于区域尺度的近岸形态动力学建模和洪水易发地区的基础设计状态。教育和推广工作将扩大各级的参与，包括：(1)在三所合作院校招收、保留和教育代表性不足的学生；(2)在具有不同城市环境和人口的三个沿海州，让科学教师参与沿海基础设施和社区弹性培训；(3)通过改变设计和减灾协议，提高沿海居民的福祉。该项目将在泥沙输运与冲刷、非饱和与饱和土力学、洪水流体动力学等方面建立桥梁。这一目标将通过将冲刷和荷载的时空变化与复杂城市环境中浅层洪水流动的动态以及地表结构周围和下方非饱和土壤中的水滞回相关联来实现。本课题的研究目标是：(1)在不同的水流和土壤状态下，单结构和阵列结构的冲刷模式；(2)在不同性质（即成分、相对密度、初始含水量）的低细粒含量土壤中，基础冲刷的开始和发展；(3)波浪作用和水致超孔隙压力作用下的地基相互作用响应；(4)非饱和地基浅基础的摇摆响应；(5)改进了开源欧拉两相模型框架，以完整描述海底稳定性和冲刷；(6)结合基于有效应力的扩展子模型和修正的微水压缩性求解器，模拟高覆盖层部分排水和非饱和条件下的土壤行为。该项目的长期目标是创建公共领域的工具，用于在极端沿海洪水条件下对复杂的城市和非城市环境进行可靠的冲刷预测。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Foundation scour is one of the primary causes of structural damage in coastal communities during flooding events. This project will leverage state-of-the-art in wave flume physical modeling, geotechnical centrifuge modeling, and numerical simulation to answer a number of critical and open questions related to the interactions among extreme flood flow, soil, and structure which lead to scour and foundation failure—shifting the paradigm in the current understanding of key physical processes in flood-induced scouring process in complex urban setting. Enhancement of open-source multi-physics computational tool for coastal hazard mitigation will provide a strong multi-disciplinary modeling platform to the broader civil and coastal engineering research community. The new parameterization set for extreme scour-liquefaction resulted from the fundamental knowledge-gain will benefit region-scale nearshore morphodynamic modeling and the state of foundation design in flood-prone areas. The education and outreach efforts will broaden the participation at all levels including: (1) recruitment, retention, and education of underrepresented students in three collaborating institutions; (2) engaging science teachers in three coastal states with different urban settings and population, in coastal infrastructure and community resiliency training; and (3) enhancing the well-being of the coastal residents through changing the design and hazard mitigation protocols.This project will bridge the state-of-the-art in sediment transport and scour, unsaturated and saturated soil mechanics, and hydrodynamics of flood flow. This goal will be achieved by correlating the spatiotemporal variations of scouring and loading with the dynamics of shallow flood flows within complex urban setting and water hysteresis in unsaturated soils around and underneath surface structures. The research objectives of this project are to understand: (1) scouring patterns of single and array of structures, under various flow and soil states; (2) initiation and progression of foundation scouring in low fines content soils of varying properties (i.e., composition, relative density, initial water content); (3) soil-foundation interaction response under simultaneous wave action and hydraulically-induced excess pore pressure; (4) rocking response of shallow foundations in unsaturated ground; (5) enhancement of an open-source Eulerian two-phase modeling framework for a complete description of seabed stability and scour; and (6) incorporating an extended effective stress-based sub-model and a revised solver for slight water compressibility to simulate soil behavior in partially drained and unsaturated condition with high overburden. The long-term goal of this project is to create public-domain tools for reliable scour predictions of complex urban and non-urban settings, under extreme coastal flooding conditions.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.