A potential new frost heave mechanism in high-speed railway embankments

Substantial frost heave has been observed in coarse fills in high-speed railway embankments. These coarse fills have very low water contents, and are located above the groundwater table. In an attempt to explain the unexpected frost heave, it is proposed that cyclic train loads cause the development of excess pore water pressure in the underlying subgrade soil, and hence ‘pump’ up the water table to the frost front, which in turn feeds the formation of ice and results in continuous frost heave. A simple quantitative model is then developed to simulate the pumping-enhanced frost heave. The numerical results show that the proposed mechanism can indeed provide a rational explanation for the otherwise unexpected frost heave. The engineering implications of this new frost heave mechanism are also discussed, in the context of designing frost heave mitigation measures in seasonally frozen regions.