Transient Flow-Induced Soil Failures of Coastal Structures

在风暴潮期间，瞬时流体压力可导致严重的土壤破坏，包括瞬时冲刷、边坡失稳、滑动、下渗、底鼓、内部侵蚀和液化。 本项目的目标是：（1）开发先进的数值工具，以研究不同模式的瞬变流引起的土壤破坏的海岸结构，（2）开发故障功能，为每一个模式，并确定故障模式之间的关系，和（3）量化的影响，流量和土壤变量的性能典型的海岸结构受到风暴潮。 我们将扩展PI Young开发的完全耦合的波浪泥沙输运模型，以模拟任意几何形状的近场波浪上升和下降以及相关的瞬态冲刷。 将考虑底部摩擦和渗透性、沉积物输运引起的动量转移、河床形态变化以及波浪破碎和与多孔介质接触引起的能量耗散的影响。 将包括概率模型，以表示流入边界处的有效波高、峰值周期和平均方向的场。 为了模拟海岸结构物的瞬态流致土壤破坏，有限体积流求解器将与DYNAFLOW完全耦合，DYNAFLOW是一种由共同PI普雷沃斯特在过去二十年中开发的有限元程序。 DYNAFLOW配备了非线性、非弹性、多屈服本构模型（已通过现场和离心实验验证），用于模拟动态诱导的超孔隙水压力累积以及由此导致的非均匀土壤材料的软化和/或硬化。 基于非线性破坏力学的有效X-FEM方法将用于模拟土壤系统中的滑移破坏传播。 我们将研究不同组的无量纲波和土壤变量的动态响应的理想化和特定网站（概念表示的防洪墙系统在庞恰特雷恩湖）结构和水深的影响。 最后，我们将调查目前的设计建议的充分性，并开发新的/改进的故障功能和故障关系，以提供必要的工具，为现实的可靠性为基础的设计沿海structs.An项目的一个重要组成部分是跨学科合作的三个共同PI？在水文灾害，固体和流体动力学的专业知识，以及来自美国陆军工程兵团的咨询小组的参与，共同拥有解决问题的关键专业知识。我们的教育目标是：（i）创造知识并向学术、工业和政府部门传播知识;（ii）就风暴工程的关键问题教育新一代科学家和工程师;（iii）增加少数民族和贫困学生对科学和工程的参与。为了实现这些目标，我们将：（1）与伍德罗·威尔逊公共事务学院合作举办多学科研讨会系列，以更好地教育公众对风暴工程的重要性;（2）与团队成员和顾问小组定期举行会议;（3）通过独立研究项目，高级论文和暑期实习，让本科生参与研究;（4）与其他研究人员一起研究风暴工程。以及（4）通过普林斯顿大学的外展计划，包括NSF赞助的REU（通过PRISM在普林斯顿大学协调）和普林斯顿大学材料研究所，鼓励高中生和本科生参与其中。

During a storm surge, transient fluid pressures can lead to serious soil failures, including transient scour, slope instability, sliding, underseepage, bottom heave, internal erosion, and liquefaction. The objectives of this project are to (1) develop advanced numerical tools to investigate the different modes of transient flow-induced soil failures of coastal structures, (2) develop failure functions for each mode and identify relationships between failure modes, and (3) quantify the influence of flow and soil variables on the performance of typical coastal structures subject to storm surges. We will extend a fully coupled wave-sediment transport model developed by PI Young to simulate near-field wave runup and rundown, and associated transient scour, over arbitrary geometries. The effects of bottom friction and permeability, momentum transfer due to sediment transport, changes in bed morphology, and energy dissipation due to wave breaking and contact with porous media will be considered. Probabilistic models will be included to represent the fields of significant wave height, peak period, and mean direction at the inflow boundary. To simulate transient flow-induced soil failures of coastal structures, the finite volume flow solver will be fully coupled with DYNAFLOW, a finite element program developed by co-PI Prevost over the last twenty years. DYNAFLOW is equipped with nonlinear, inelastic, multi-yield constitutive models (which have been validated with field and centrifuge experiments) to simulate dynamically induced excess pore water pressure buildup and resulting softening and/or hardening of inhomogeneous soil materials. An efficient X-FEM approach based on nonlinear failure mechanics will be employed to model slip failure propagation in soil systems. We will examine the influence of different groups of non-dimensional wave and soil variables on the dynamic response of idealized and site-specific (conceptual representation of the levee-flood wall system at Lake Ponchatrain) structure and bathymetry. Finally, we will investigate the adequacy of current design recommendations, and develop new/improve failure functions and failure relationships to provide the necessary tools for realistic reliability-based design of coastal structures.An essential ingredient of this project is the cross-disciplinary collaboration of the three co-PI?s with expertise on hydrological hazards, solid and fluid dynamics, and the participation of an advisory panel from the US Army Corps of Engineers, together possessing critical expertise for tackling the problem. Our educational goals are to: (i) create and disseminate knowledge to the academic, industrial and government sectors; (ii) educate a new generation of scientists and engineers about problems critical to storm engineering; and (iii) increase participation of minority and underprivileged students in science and engineering. To implement these goals, we will: (1) organize multi-disciplinary seminar series in collaboration with the Woodrow Wilson School of Public Affairs to better educate the public about the importance of storm engineering; (2) hold regular meetings with team members and advisory panel; (3) include undergraduates in the research through independent research projects, senior theses, and summer internships; and (4) encourage involvement of high school and undergraduate students through outreach programs at Princeton, including the NSF-sponsored REU (coordinated at Princeton through PRISM) and the Princeton University Materials Institute.