Numerical analysis of coupled water, heat and stress in saturated freezing soil

Clapeyron equation can be applied in freezing soil to describe the relationship among temperature, water pressure and ice pressure when ice and water coexist in phase equilibrium. The mathematical deduction shows that the driving force that makes the unfrozen water in soil moves from high temperature area to low temperature area is determined by gravity, temperature and pore pressure. Upon proposing the concept of separating void ratio as a judge criterion for the formation of ice lenses, adjusting the hydraulic conductivity to describe the unfrozen water gathering at the front of ice lenses and the growth of ice lens, a mathematical model of coupled water, heat and stress is established. A typical process of coupled water, heat and stress that happens in a saturated freezing soil column is simulated by COMSOL Multiphysics simulation software. The amount of frost heave is calculated, and the result of simulation gives the distribution bar graph of ice lenses and distribution curves of temperature, equivalent water content and pore pressure, and shows how they change.

► We establish a strict mathematical model for coupled water, heat and stress fields.
► The separating void ratio is introduced to judge the formation of ice lenses.
► A numerical example is given by COMSOL Multiphysics simulation software.
► The temperature, water content, frost heave and ice lenses have been simulated.