Analysis of coupled heat‐fluid transport in partially frozen soil

TLDR

Water transport in partially frozen soils can be understood by analogy to unsaturated soil processes. A Darcian framework coupled with a numerical model was used to analyze heat‑fluid transport during freezing and thawing, examining how soil type and initial conditions affect water redistribution and infiltration in a hypothetical soil column. The model predicts that upward water redistribution to a freezing zone is slower in finer soils and deeper water tables, that melting redistributes water more slowly than freezing, and that infiltration into partially frozen soil markedly influences groundwater table dynamics.

Abstract

An analogy can be made between the mechanisms of water transport in partially frozen soils and those in unsaturated soils. By use of this analogy a Darcian approach is applied to the analysis of coupled heat‐fluid transport in porous media with freezing and thawing. With the aid of a numerical model, freezing‐affected soil‐water redistribution and infiltration to frozen soil are examined from a phenomenological point of view, and the effects of soil type and initial conditions on the response of a hypothetical soil column are studied. In general, the model shows that the rate of upward redistribution of soil water to a freezing zone at the soil surface decreases from coarse‐textured soils to fine‐textured soils and decreases with increase in depth to the water table. Subsequent redistribution during melting of the frost wedge is shown to occur at a rate less than that associated with freezing. Infiltration to partially frozen soil is also shown to have a significant influence on soil‐water redistribution and the response of the groundwater table.