Freezing processes in porous media: Formation of ice lenses, swelling of the soil

When moist porous soil is freezing, a volume expansion is generally observed. The volume increase is mainly due to a water migration process from the base of the soil up to the freezing front, which separates the lower unfrozen part from the upper frozen one. The coupled heat-mass transfer process is accompanied, under particular conditions, to the formation of pure ice segregated layers. Conversely, if the freezing process is too fast or the overburden pressure acting on the column of soil is relevant, no macroscopic accumulation of ice is observed. generally accepted that a thin transition region (frozen fringe), where water and ice coexist in the porous space, separates the unfrozen from the frozen parts of the soil. rong interest on ground freezing is motivated by at least two reasons: preventing frost damages produced on roads pavements, pipelines, or other structures, and predicting the effects of artificial-freezing techniques for tunneling or underground constructions. going to present a mathematical model of frost heave where water is driven through the porous space by the coupling of a pressure and a chemical gradient. In particular, the interest is focused on detecting which are the boundary values for temperature (or thermal flux) that determine the process of lens formation or frost penetration, once the properties of the soil are known.