A method for frost jacking prediction of single pile in permafrost

In this paper, a model is proposed to simulate frost jacking performances of a pile foundation within an axisymmetric pile-soil system through a coupling strategy. We consider three diversified stages for frost heave of adjacent foundation soil below freezing point, where mathematical expressions for the volumetric strain are given in terms of volumetric ice content, negative temperature and porosity. A modified strain-softening model characterizing frozen soil-pile interactions is established based on experimental results, taking into account the effects of normal pressure, negative temperature and moisture content. The proposed computational approach is then illuminated and validated via the numerical example of a simplified bridge pile foundation under natural permafrost condition. Variation of temperature regime, volumetric ice content, displacement and stress over time is analyzed. This model can be further applied to evaluating effects of different countermeasures that mitigate frost jacking hazard of single pile subjected to cold climate.