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.

这个工程研究启动（ERI）奖将支持研究，调查在冻土深层结构基础的动态行为的演变。桩对地震振动的反应受温度升高引起的土壤性质变化的影响。阿拉斯加的地震比美国任何其他地区都多，事实上，阿拉斯加是世界上地震最活跃的地区之一。由于冻土的力学性质与温度有关，土壤温度变化对冻土区的地震振动有很大影响，因此，基础设施目前正受到与解冻有关的沉降和频繁的地震活动的破坏。因此，土桩基础系统的动力特性，这是至关重要的结构的稳定性，不能预测从多年冻土或非多年冻土地区的测量。这项研究将描述和评估正在进行的冻土退化对桩基在地震灾害面前的动力行为的影响。该项目将为来自克拉克森大学和阿拉斯加大学费尔班克斯的本科生提供研究经验;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推广计划，演示模型桩在土层中的动态响应。该ERI研究项目的目标是表征退化永久冻土中桩基的动态行为，这些知识可用于开发受地震和气候变化影响的桩基弹性，可持续设计，并增加使用寿命，同时降低基础设施的维护和运营成本。为了实现这一目标，将追求两个目标：（1）的厚度和分布的冻结和未冻结的土壤层的土壤桩系统的动态刚度和阻尼使用实验室规模的测试的特性;和（2）调查季节性冻融对桩的动态行为在阿拉斯加永久冻土使用现场振动测试。本文将回答以下几个基本问题：（1）在不连续多年冻土区，地温分布对桩土系统动力特性的影响;（2）冻融引起的土层热力学性质变化在桩基动力响应中的作用是什么？结合室内试验和现场试验结果，对多年冻土区非线性Winkler地基动力梁模型进行了改进。该研究将为开发和调查连续和不连续永久冻土区的创新基础解决方案提供基础，从而提高北极地区的社区复原力。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。