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。这场大地震造成了持续时间较长的地面震动，随后引发了巨大的海啸洪水。了解地震和海啸综合事件如何影响土壤不稳定，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。在地震期间，土壤不稳定主要是由液化引起的；也就是说，土壤就像液体一样，土壤支撑上面的建筑物和基础设施的潜力严重降低。将制定有效的战略来设计具有复原力的关键建筑和基础设施。作为该项目的一部分，一名研究生将接受地质和流体力学基础知识的教育，这将为她成为一名跨学科的多种自然灾害研究人员做好准备。将制作一系列教育视频，以鼓励大学生和高中生从事科学和工程职业。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，可能是通过残余的液化和流态化，然后是随后发生的海啸，可能是通过瞬间的液化和冲刷。这一假设产生了以下问题：(1)地震引起的土壤不稳定与海啸引起的土壤不稳定是如何相互作用的？(2)地震和海啸之间经过的时间如何影响这种相互作用？(3)地震和海啸的综合作用是否加剧了沿海建筑物周围的冲刷？为了回答这些问题，将使用加州大学戴维斯分校的离心机设施进行实验室实验。离心机实验将旨在揭示连续地震-海啸荷载引起的土壤不稳定的基本机制，并反过来发现这种荷载情景如何影响土壤-流体-结构系统。

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.