Canopy effect: Water vapor transmission in frozen soils with impermeable surface

Authors: HOU, BOWEN - Northwest Agricultural & Forestry University; JIN, HUIJUN - Chinese Academy Of Sciences; Flerchinger, Gerald; LV, JAILONG - Northwest Agricultural & Forestry University; HE, HAILONG - Northwest Agricultural & Forestry University

Submitted to: Acta Geotechnica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2023
Publication Date: 4/14/2023
Citation: Hou, B., Jin, H., Flerchinger, G.N., Lv, J., He, H. 2023. Canopy effect: Water vapor transmission in frozen soils with impermeable surface. Acta Geotechnica. https://doi.org/10.1007/s11440-023-01845-0.
DOI: https://doi.org/10.1007/s11440-023-01845-0

Interpretive Summary: Frozen soil occurs on about 75% of the land area in the Northern Hemisphere, of which permafrost accounts for about 24%. Great efforts have been made to better understand the effects of climate change on permafrost degradation and associated hydrological, chemical, and biological processes. The freezing/thawing cycle in cold regions and degradation of permafrost significantly impacts hydraulic, thermal, and mechanical properties of foundation soils of engineered infrastructures, which subsequently affect their durability and stability. Vapor transport to the freezing front and subsequent condensation contributes to excessively high ice contents, frost heave, soils impermeable to water, and subsequent flooding. This review paper systematically summarizes the mechanisms of water-heat-vapor migration, current measurement methods, and the existing models that can simulate water-heat-vapor migration, which researchers and practitioners can use for scientific guidance and reference for research and engineering construction in cold regions.

Technical Abstract: Approximately a quarter of Northern Hemisphere territory is covered by permafrost where numerous reserves of energy and mineral resources exist. Therefore, infrastructures, such as railways, highways, airports, oil and gas pipelines, bridges, tunnels, and power grids, have always been the focus of development in cold regions. However, the durability and stability of these infrastructure facilities are affected by the freezing-thawing cycle of the active layer. Disasters such as permafrost degradation, frost heave, thaw slumping, and subsidence have largely damaged cold region infrastructure that is costly and laborious for rehabilitation. This severely constrains the social and economic development of cold regions. Meanwhile, global climate change and intensification of human activities make this problem even more complex and unpredictable. Great progress has been made in the past by reducing temperature rise of the frozen ground surrounding and capillary water induced frost heave beneath the infrastructure foundations during engineering design, construction, and maintenance. It is known that water vapor transmission can increase water content beneath infrastructures, resulting in frost heaving damage in cold regions. However, there is a lack of deep understanding of the significance of water vapor transmission under freezing-thawing cycles. In addition, insufficient research methods and technologies lead to inadequate research on vapor transmission compared to water flow or capillary rise. The objective of this study was therefore to review the research progress of water vapor transmission under freezing-thawing cycles. We reviewed topics including water vapor source, transmission process, influencing factors and measurement techniques of water vapor under freezing-thawing cycles. Pros and cons of available water-heat-vapor test methods and mechanisms of frost heaving caused by water vapor transmission are discussed. The existing water vapor transmission models are collated, while a variety of numerical simulation software tools that depict the water vapor transmission process are summarized. The review ends with critical discussions on shortcomings of currently available research and future perspectives on water-heat-vapor transmission.