Although high-speed railway (HSR) subgrades in cold regions are filled with coarse-grained soil (CGS), they still undergo frost-heaving displacement. The liquid water–vapour migration mechanism can explain the frost-heaving process; therefore, the characteristics of liquid water–vapour migration in CGS are investigated in this study. The results show that in CGS, vapour migration is dominant under unidirectional freezing and dynamic loading. The water redistribution in the frozen zone and freezing front is primarily caused by vapour migration, whereas that in the unfrozen zone is primarily caused by liquid water migration. The final migration height of liquid water and the amount of vapour migration are positively correlated with the amplitude and frequency of dynamic loading. Continuous pore-structure changes and soil-particle movement provide favourable conditions for vapour migration, which are amplified by increasing the dynamic loading amplitude or frequency. A pumping action produced by dynamic loading exists inside CGS. In the design and maintenance of HSR subgrades in cold regions, vapour migration merits careful consideration because it induces more than 50% of the frost-heaving displacement.

尽管寒冷地区的高速铁路（HSR）路基充满了粗糙的土壤（CGS），但它们仍然经历了冻胀位移。液态水蒸气迁移机制可以解释霜冻过程。因此，本研究研究了CGS中液态水蒸气迁移的特征。结果表明，在CGS中，在单向冻结和动态载荷下，蒸汽迁移占主导地位。冻结区和冻结区中的水重新分配主要是由蒸汽迁移引起的，而未冻结区中的水重新分配主要是由液态水迁移引起的。液态水的最终迁移高度和蒸汽迁移量与动态载荷的幅度和频率成正相关。连续的孔隙结构变化和土壤颗粒运动为蒸汽运移提供了有利条件，通过增加动态载荷振幅或频率来扩大这些条件。通过动态加载产生的泵送作用存在于CGS内部。在寒冷地区高铁路基的设计和维护中，蒸气迁移值得仔细考虑，因为它引起了超过50％的冻胀位移。