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

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.