Vapour migration and condensation into ice have been found to be the main reasons for frost heave in coarse-grained soils. The mechanism of this kind of frost heave is less understood than the traditional one due to condensation of liquid water. In particular, an accurate mathematical criterion is required to explain when and where the ice lens will form in coarse-grained soils. This study focuses on the migration of vapour from a mesoscale point of view. Mechanical equilibrium on the vapour-ice interface is discussed, and the rate of frost heave is acquired theoretically. A new criterion for ice lens initiation is proposed by analysing the forces acting at the vapour-ice interface. The influence of the overburden pressure and temperature gradient on the heaving rate is discussed. The new criterion provides a theoretical basis to understand frost heave in coarse-grained soils and can be used in numerical models for simulating frost damage in cold regions.

已发现蒸汽迁移和凝结成冰是粗粒土壤发生冻胀的主要原因。由于液态水的凝结，这种冻胀的机制比传统的冻胀机制还不清楚。特别是，需要一个准确的数学标准来解释冰透镜何时何地在粗粒土壤中形成。本研究从中尺度的角度关注蒸汽的迁移。讨论了水汽-冰界面的力学平衡，从理论上得到了冻胀率。通过分析作用在蒸气-冰界面的力，提出了一种新的冰晶状体启动标准。讨论了上覆地层压力和温度梯度对隆起速率的影响。