Numerical Modelling Ice Lens Formation and Frost Heave in Unsaturated Soils

Frost heave is a typical thermo‐hydro‐mechanical coupling process, which can lead to significant threats to the infrastructures in cold regions. The initiation and growth of ice lenses is the core issue to understand the process of frost heave. But this process has not been well modelled in previous studies. It is hard to accurately model the formation of ice lenses and the contribution of the vapour phase during the freezing process. This study presents a novel frost heave model that accounts for the effects of vapour migration in unsaturated soils, which is implemented in a C++ simulation programme with an interactive user interface. The model reveals periodic frost heave variations due to cooling gradients and highlights the impact of vapour on ice lens formation under low moisture conditions. It also demonstrates the relative importance of liquid and vapour fluxes with moisture content, with vapour migration playing a key role in frost heave in coarse‐grained soils. These new findings provide new insights into frost heave mechanisms and challenge traditional ice lens formation criteria. In addition, the model effectively simplifies boundary conditions and improves computational stability and efficiency. These advancements can improve frost heave prediction and deepen the understanding of soil freezing mechanisms, offering valuable insights for infrastructure applications.