Collaborative Research: Experimental Quantification of Tsunami-driven Debris Damming on Structures

该项目将调查海啸期间建筑物前堆积的瓦砾，即瓦砾筑坝，如何导致海啸流对建筑物施加的力量增加。为了更好地了解因筑坝而增加的海啸力量的幅度、导致力量增加的机制以及筑坝荷载的可变性，俄勒冈州立大学国家科学基金会(NSF)支持的自然灾害工程研究基础设施(NHERI)将在大型波浪水槽中的高架建筑上进行实验。更好地了解海啸引发的碎片筑坝负荷可用于(1)改进现有设计准则，以建造更安全的建筑物，(2)确定影响碎片筑坝的因素，以确定有助于减少或减轻筑坝负荷的措施，以及(3)改进对现有建筑物的海啸脆弱性评估，以确定风险和复原力。该项目还将包括让高中生参与实验的外联活动，为本科生和研究生提供参与实验和计算建模的研究机会，以及为研究人员和执业工程师举办的网络研讨会，以促进采用研究成果。这项研究将有助于国家科学基金会在国家减少地震灾害计划(NEHRP)中发挥作用。在大型波浪水槽中的实验将集中于确定在高架结构(如垂直疏散结构)的一楼柱上造成海啸驱动的碎片筑坝和相关荷载的机制。这些机制包括但不限于，岩屑-结构、泥石流、岩屑-岩屑相互作用、流动和速度场的变化，以及有效建筑物投影面积的变化。实验将使用均匀的碎屑以及形状、大小、密度和数量不同的非均匀碎屑混合物。一种新的迭代实验设计策略将被用来解决指数级的大量潜在实验条件，并量化负载中的不确定性。此外，新的无量纲参数将被用来量化筑坝的可能性和超过设计筑坝荷载的概率。对实验数据的分析和补充的计算流体力学模拟的结果将提供关于碎石如何与其他碎石和结构相互作用的新知识，以及海啸流场(速度和深度)如何因泥石坝而改变。由此产生的数据集将通过NHERI数据库与研究社区共享(https://www.DesignSafe-ci.org).This奖反映了美国国家科学基金会的法定使命，并已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。

This project will investigate how the accumulation of debris in front of buildings, i.e., debris damming, during tsunami events leads to an increase in the forces imposed by tsunami flow on structures. To better understand the magnitude of increase in tsunami forces due to damming, the mechanisms that cause increased forces, and the variability in damming loads, experiments will be conducted on elevated buildings in the large wave flume at the National Science Foundation (NSF)-supported Natural Hazards Engineering Research Infrastructure (NHERI) facility at Oregon State University. A better understanding of tsunami-driven debris damming loads can be used to (1) improve existing design guidelines to construct safer buildings, (2) identify factors that affect debris damming to determine measures that help reduce or mitigate the damming loads, and (3) improve tsunami vulnerability assessment of existing buildings for characterizing risk and resilience. The project will also include outreach activities to engage high school students in the experiments, research opportunities for undergraduate and graduate students to participate in the experiments and computational modeling, and webinars for researchers and practicing engineers to promote the adoption of the research findings. This research will contribute to the NSF role in the National Earthquake Hazards Reduction Program (NEHRP). The experiments in the large wave flume will focus on identifying the mechanisms that cause tsunami-driven debris damming and associated loads on the first floor columns of an elevated structure, such as a vertical evacuation structure. These mechanisms include, but are not limited to, debris-structure, debris-flow, debris-debris interactions, changes in flow and velocity fields, and changes in effective building projected area. The experiments will use homogeneous debris as well as non-homogeneous debris mixtures with varying shapes, sizes, densities, and quantities. A novel iterative experimental design strategy will be used to address the exponentially large number of potential experimental conditions and to quantify the aleatory uncertainty in the loads. Additionally, new dimensionless parameters will be used to quantify the likelihood of damming and the probability of exceeding design damming loads. The results from the analysis of experimental data and supplementary computational fluid dynamics simulations will provide new knowledge on how debris interacts with other debris and the structure, and how tsunami flow fields (speed and depth) change because of debris damming. The resulting data set will be shared with the research community via the NHERI Data Depot (https://www.DesignSafe-ci.org).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.