ERI: Evolution of Dynamic Behavior of Pile Foundations in Permafrost with Climate Change

ERI：永久冻土中桩基动态行为随气候变化的演变

• 批准号: 2347680
• 负责人: Suguang Xiao
• 金额: $ 20万
• 依托单位: Clarkson University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2347680&HistoricalAwards=false
• 关键词: ERI; Evolution; Dynamic; Behavior; Pile

This Engineering Research Initiation (ERI) award will support research that investigate the evolution of the dynamic behavior of deep structural foundations in permafrost. Pile response to vibrations from earthquakes is affected by changes in soil properties from increasing temperatures. Alaska has more earthquakes than any other region of the United States and is, in fact, one of the most seismically active areas of the world. Infrastructure is now being damaged by both thaw-related settlements and frequent seismic activity because mechanical properties of permafrost are temperature dependent and soil temperature variation significantly impacts seismic vibrations in the permafrost region. Consequently, dynamic behaviors of a soil-pile foundation system, which are critically important to the stability of a structure, cannot be predicted from measurements taken from permafrost or non-permafrost regions only. This research will characterize and assess the impact of ongoing permafrost degradation on the dynamic behaviors of pile foundations in the face of seismic hazards. The project will provide research experiences for undergraduates from Clarkson University and the University of Alaska Fairbanks; they will assist with instrumentation, soil testing, in situ tests, and data processing. In addition, an educational and outreach program for middle school science classes that demonstrates dynamic response of model piles in layers of soil will be implemented. The goal of this ERI research project is to characterize the dynamic behaviors of pile foundations in degrading permafrost, knowledge that could be used to develop resilient, sustainable designs for piles subject to earthquakes and climate change, and increase service life while reducing maintenance and operation costs of infrastructure. To achieve this goal, two objectives will be pursued: (1) characterization of the effects of thickness and distribution of frozen and unfrozen soil layers on the dynamic stiffness and damping of soil-pile systems using laboratory-scale tests; and (2) investigation of seasonal freeze-thaw effects on the dynamic behavior of piles in Alaska permafrost using in situ vibration testing. The following fundamental questions will be answered: (1) How does the temperature distribution of the ground affect the dynamic behavior of the soil-pile system in discontinuous permafrost regions? and (2) What is the role of changes in thermomechanical properties of the soil layers caused by freeze-thaw in the dynamic response of pile foundations? By integrating experimental results from both laboratory and field tests, the research will improve the model of a dynamic beam on a nonlinear Winkler foundation for permafrost regions. This research will provide the basis for developing and investigating innovative foundation solutions for continuous and discontinuous permafrost zones, thereby increasing community resilience in the Arctic.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.

该工程研究启动（ERI）奖将支持研究深层结构基础动态行为的演变的研究。地震振动的桩反应受到温度升高的土壤特性变化的影响。阿拉斯加的地震比美国的任何其他地区都多，实际上是世界上最活跃的地区之一。现在，基础设施被融化相关的定居点和频繁的地震活动损坏，因为多年冻土的机械性能是温度依赖性的，土壤温度的变化显着影响了永久冻土区域的地震振动。因此，对于仅从永久冻土或非层状区域进行的测量，无法预测土壤铜基粉底系统的动态行为，这对于结构的稳定性至关重要。这项研究将表征和评估持续的多年冻土降解对面对地震危害的桩基础动态行为的影响。该项目将为克拉克森大学和阿拉斯加大学Fairbanks大学的大学生提供研究经验；他们将协助仪器，土壤测试，原位测试和数据处理。此外，还将实施一项针对中学科学课程的教育和外展计划，以证明在土壤层中模型堆的动态反应。这个ERI研究项目的目的是表征堆积基础的动态行为，以降解多年冻土，可用于开发易于地震和气候变化的堆积的弹性，可持续设计，并降低服务寿命，同时降低基础设施的维护和运营成本。为了实现这一目标，将实现两个目标：（1）使用实验室规模的测试来表征厚度和冷冻和未冻结土壤层对土壤铅系统动态刚度和阻尼的影响； （2）使用原位振动测试研究了季节性冻结对阿拉斯加多年冻土的动态行为的影响。将回答以下基本问题：（1）地面的温度分布如何影响不连续的多年冻土区域中土壤 - 毛皮系统的动态行为？ （2）由冻融引​​起的土壤层的热机械性能变化在桩基础的动态响应中的作用是什么？通过整合实验室和现场测试的实验结果，该研究将改善在多年冻土区域的非线性Winkler基金会上的动态光束模型。这项研究将为开发和调查连续和不连续的多年冻土区的创新基础解决方案提供基础，从而提高了北极地区的社区韧性。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来通过评估来支持的。