Artificial ground freezing of fully saturated soil: Thermal problem

Freezing of water in porous media such as soil results in a change of mechanical and thermal properties. This change of properties is exploited during artificial ground freezing (AGF) employed in tunneling, during open excavations, and for retaining structures. In this paper, a phase-change model for the simulation of freezing of fully saturated soil is presented. Disregarding the influence of mechanical loading on the freezing process, only the solution of the thermal problem, i.e., determination of the temperature field, is addressed. The (macroscopic) thermal properties are related to the material parameters of the different material phases, such as soil particles, water, and ice. This approach allows us to minimize the number of input parameters of the phase-change model and to account for the change of thermal properties in the course of the freezing process. The performance of the proposed model is illustrated by the reanalysis of freezing experiments and of an AGF construction site in Vienna, Austria.