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

基础冲刷是洪水期间沿海社区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拟、土工离心模拟和数值模拟来回答一些关键的和开放的问题，这些问题与极端洪水、土壤和结构之间的相互作用有关，这些相互作用导致冲刷和基础破坏，从而改变了目前对复杂城市环境中洪水引起的冲刷过程中关键物理过程的理解。增强用于沿海减灾的开源多物理计算工具将为更广泛的土木和沿海工程研究社区提供强大的多学科建模平台。新的参数化设置的极端液化的基础知识的增益，将有利于区域尺度的近岸地貌动力学模拟和基础设计的状态在洪水易发地区。教育和外联工作将扩大各级的参与，包括：（1）在三个合作机构招募、保留和教育代表性不足的学生;（2）让三个城市环境和人口不同的沿海州的科学教师参与沿海基础设施和社区复原力培训;（3）通过改变设计和减灾协议，提高沿海居民的福祉。该项目将连接沉积物输运和冲刷、非饱和和饱和土壤力学以及洪水流体动力学的最新技术。这一目标将通过将冲刷和荷载的时空变化与复杂的城市环境中的浅洪水流的动态以及地表结构周围和下方的非饱和土壤中的水滞后相关联来实现。本项目的研究目标是了解：（1）在各种水流和土壤状态下，单个和阵列结构物的冲刷模式;（2）在不同性质的低细粒含量土壤（即，（3）在波浪作用和水力引起的超孔隙压力同时作用下的土-基础相互作用响应;（4）非饱和地基中浅基础的摇摆响应;（5）增强开源欧拉两相模拟框架，以完整描述海床稳定性和冲刷;（6）采用扩展的有效应力子模型和修正的微水压缩性求解器模拟高覆盖层非饱和部分排水条件下的土体性状。该项目的长期目标是创建公共领域的工具，用于在极端的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NSF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.