Coupled Thermo-Hydro-Mechanical Behavior of Soils Subjected to Freeze-Thaw Cycles

冻融循环下土壤的热-水-机械耦合行为

• 批准号: 2034204
• 负责人: Marcelo Sanchez
• 金额: $ 36.15万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2034204&HistoricalAwards=false
• 关键词: Coupled; Thermo; Hydro; Mechanical; Behavior

Seasonally frozen soils occupy approximately 55 percent of the earth's total surface land. Rising air temperatures particularly in the upper latitudes are causing an increase in ground temperatures, intensifying permafrost degradation. A good understanding of the behavior of frozen soils is critical for safe and economical design of civil infrastructure in regions seasonally exposed to freezing temperatures. This aspect is particularly relevant considering the recent discovery of fossil fuels (e.g., gas hydrates) near the Arctic Circle, with the associated needs of developing new infrastructure in these regions. Moreover, artificial ground freezing technique has become an extraordinary ally for building deeper, quicker, bigger and more complex geotechnical structures (e.g., tunnels in large urban areas). However, some recent construction issues associated with this methodology have shown the need to gain a better understanding of the fundamental aspects associated with the complex nature of frozen soil behavior. The outcomes of the research contributions in this project will be incorporated into undergraduate and graduate curricula. The project offers opportunities for graduate and undergraduate students novel technical skills in geotechnical engineering and a better understanding of the soil freeze-thaw cycles and its impact on the environment and built infrastructure. The project will advance the general area of thermal geotechnics, with contributions towards problems involving soils subjected to freeze-thaw cycles. The overarching goal of this project is to advance the current understanding of frozen soil behavior. Particularly, the following specific objectives will be pursued: (i) gain a better understanding of the key features associated with the behavior of frozen soils, including permafrost degradation, the effect of freeze-thaw cycles, the impact of stress history, and the interaction between the soil-fabric and the changes in water-volume occurring during water-phase transformations; (ii) produce high-quality experimental data related to the behavior of frozen soils including a variety of stress levels, temperatures, stress history, and permafrost degradation scenarios, which will contribute to expanding the current database in this area; and (iii) develop advanced constitutive and numerical codes to tackle problems involving frozen soils subjected to complex freeze-thaw cycles and loading conditions. A combined experimental, and numerical investigation program will be conducted to achieve these objectives. Research findings will be disseminated through scientific publications and a dedicated website. This research aligns with NSF's Navigating the New Arctic program.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.

季节性冻土约占地球总表面面积的 55%。气温升高，尤其是高纬度地区气温升高，导致地面温度升高，加剧了永久冻土退化。充分了解冻土的行为对于季节性暴露于冰冻温度的地区的民用基础设施的安全和经济设计至关重要。考虑到最近在北极圈附近发现的化石燃料（例如天然气水合物）以及在这些地区开发新基础设施的相关需求，这一点尤其重要。此外，人工地面冻结技术已成为建造更深、更快、更大和更复杂的岩土结构（例如大城市地区的隧道）的非凡盟友。然而，最近与该方法相关的一些施工问题表明需要更好地了解与冻土行为复杂性相关的基本方面。该项目的研究成果将纳入本科生和研究生课程。该项目为研究生和本科生提供了岩土工程方面的新颖技术技能的机会，以及更好地了解土壤冻融循环及其对环境和建筑基础设施的影响。该项目将推进热岩土工程的整体发展，为解决涉及冻融循环土壤的问题做出贡献。该项目的总体目标是增进目前对冻土行为的理解。特别是，将追求以下具体目标：（i）更好地了解与冻土行为相关的关键特征，包括永久冻土退化、冻融循环的影响、应力历史的影响以及相互作用土壤结构与水相转变过程中发生的水量变化之间的关系； (ii) 产生与冻土行为相关的高质量实验数据，包括各种应力水平、温度、应力历史和永久冻土退化情景，这将有助于扩大该领域的现有数据库； (iii) 开发先进的本构和数值规范，以解决涉及复杂冻融循环和载荷条件下冻土的问题。为了实现这些目标，将进行综合实验和数值研究计划。研究结果将通过科学出版物和专门网站传播。这项研究与 NSF 的导航新北极计划相一致。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Mechanical behavior of frozen soils: Experimental investigation and numerical modeling

• DOI: 10.1016/j.compgeo.2021.104361
• 发表时间: 2021-10
• 期刊: Computers and Geotechnics
• 影响因子: 5.3
• 作者: Ajay Shastri;M. Sánchez;X. Gai;Moo Y. Lee;T. Dewers