Simulation of heat–water–mechanics process in a freezing soil under stepwise freezing

Frost heave is a process coupling heat transfer, water migration, water–ice phase change and deformation. Frost heave forms various landforms, such as frost mounds, ice pitons, sorted polygons and stone circles, and potentially induces a variety of engineering failures, such as building inclination, differential engineering foundation and pavement cracking. To understand the mechanism of frost heave under complex freezing paths, we provide a numerical heat–water–mechanics model that incorporates shrinkage in an unfrozen zone and uses a water content criterion to judge the formation of the ice lens. The model is then used to simulate the moisture, temperature, deformation and ice lens of a freezing soil during stepwise freezing. The simulated results for temperature, displacement and the ice lens are in good agreement with measured data, indicating that the model can be used to describe the heat–water–mechanics process in freezing soils under a complex freezing path. The freezing path determines the soil's water content profile in a manner like that in a stepwise freezing process, where each step produces a water‐content peak at the frozen fringe of the step. The model must consider shrinkage of the unfrozen area, or the amount of frost heave would be overestimated and the predicted ice lens would unrealistically be found in the frozen zone.