Numerical simulation of artificial freezing of soils accounting for thermo-hydro-mechanical effects

Abstract

In the study a thermo-hydro-mechanical model of freezing of saturated soil is presented, with focus on numerical simulation of artificial ground freezing (AGF). Artificial freezing of saturated soils induces such process in the soils as water migration, frost heave and consolidation which can have an effect on the freezing process and surrounding areas. To take into account the important from geotechnical point of view processes the thermo-hydro-mechanical model was developed. The model is based on the fundamental balance equations of continuum media mechanics. The Clausius-Clapeyron equation and constitutive relations of poromechanics are used for describing a relationship between pore pressure, temperature, stress and strain fields. Also an inelastic strain is included accounting for an effect of frost heave. The equations of the model were implemented in Comsol Multiphysics® software and solved using the finite element method relative to variables of porosity temperature and displacement. Numerical simulation of artificial freezing of a soil stratum for a vertical shaft sinking was carried out. A mesh convergence of numerical solution was analyzed. Results of the simulation have shown the model enables to describe a frozen wall formation with a coupled change of porosity, water pore pressure, volumetric strain and mean stress.