Centrifuge Modeling of Coastal Soil-Structure Instability

2011年日本地震和海啸在日本造成了前所未有的破坏和生命损失。 这次大地震造成了长时间的地面震动，随后是巨大的海啸淹没。 事后调查小组报告说，对建筑物和基础设施的破坏往往因土壤不稳定而加剧或造成。了解地震和海啸事件如何影响土壤不稳定性，对于为过去影响美国沿海地区的类似即将发生的地震海啸事件做好准备至关重要。 在地震中，土壤不稳定主要是由液化引起的;也就是说，土壤像液体一样，土壤支撑上覆建筑物和基础设施的潜力严重降低。 在海啸淹没期间，除了水流造成的表面冲刷外，也可能发生液化。 这项研究将促进对地震和海啸综合影响引起的土壤不稳定性的理解。 将制定设计具有复原力的关键建筑物和基础设施的有效战略。作为该计划的一部分，研究生将接受地质和流体力学基础教育，这将使她成为一名跨学科的多自然灾害研究人员。 为了鼓励大学生和高中生从事科学和工程职业，将制作一系列教育视频。关于2011年的事件，人们怀疑土壤不稳定首先是由地震引发的，可能是通过残余液化和液化，然后是随后发生的海啸进一步加剧，可能是通过瞬间液化和冲刷。这一假设产生了以下问题：（1）地震引起的土壤失稳与海啸引起的土壤失稳如何相互作用？ (2)地震和海啸之间的时间间隔如何影响这种相互作用？(3)地震海啸复合灾害是否会加剧海岸结构物周围的冲刷？ 为了回答这些问题，实验室实验将使用加州大学戴维斯分校的实验室设施进行。 离心机是唯一能够对原型土壤-流体-结构系统施加连续地震-海啸载荷的实验装置。 离心实验的目的是揭示连续的地震海啸荷载引起的土壤不稳定的基本机制，并反过来发现这种加载方案如何影响土壤-流体-结构系统。 从精确控制的实验中获得的高质量和独特的数据对于基准测试和验证分析和数值预测模型将是非常宝贵的。

The 2011 Japan Earthquake and Tsunami caused unprecedented damage and loss of lives in Japan. This large earthquake created long-duration ground shaking followed by giant tsunami inundation. Post-event reconnaissance teams have reported that damage to buildings and infrastructure was often exacerbated or caused by soil instability. Understanding how combined earthquake and tsunami events affect soil instability is crucial to prepare for similar impending earthquake-tsunami events that have affected coastal areas of the United States in the past. During an earthquake, soil instability is primarily caused by liquefaction; that is, the soil acts like a liquid, and the potential for the soil to support overlying buildings and infrastructure is severely reduced. Liquefaction can also occur during the tsunami inundation in addition to scouring at the surface caused by the water current. This research will advance the understanding of soil instability caused by the combined effects of earthquakes and tsunamis. Effective strategies for designing resilient critical buildings and infrastructure will be developed. As part of this program, a graduate student will be educated in the fundamentals of geo-and-fluid mechanics, which will prepare her to become an interdisciplinary multi-natural hazards researcher. A series of education videos will be created for the purpose of encouraging college and high school students to pursue careers in science and engineering.With regards to the 2011 Event, it is suspected that soil instability was first triggered by the earthquake, presumably via residual liquefaction and fluidization, and then further promoted by the ensuing tsunami, presumably via momentary liquefaction and scour. This hypothesis produces the questions: (1) How does earthquake-induced soil instability interact with tsunami-induced soil instability? (2) How does the elapsed time between the earthquake and tsunami affect this interaction? (3) Is enhanced scour around coastal structures worsened by the combined earthquake-tsunami multi-hazard? To answer these questions, laboratory experiments will be performed using the UC Davis Centrifuge Facility. The centrifuge is the only experimental apparatus capable of imposing successive earthquake-tsunami loading on prototypical soil-fluid-structure systems. The centrifuge experiments will aim to reveal fundamental mechanisms of soil instability caused by successive earthquake-tsunami loads and in turn, discover how this loading scenario affects soil-fluid-structure systems. The high quality and unique data obtained from the precisely controlled experiments will be invaluable for benchmarking and validating analytical and numerical prediction models.