Possible frost heave mechanisms in an unsaturated high-speed railway formation

The Harbin-Dalian high-speed railway in north-eastern China has a significant portion of track foundation built on seasonally frozen ground. Wide-spread frost heave has been observed during the first winter of its operation and the heave occurred mainly in coarse fills that were considered not susceptible to frost heave. This paper analyses alternative mechanisms that may have caused the observed frost heave. The three most likely mechanisms are: poor quality control of fine content in the coarse fill, the top-down water supply mechanism and the bottom-up water supply mechanism. The likelihoods of these mechanisms are analysed against observed field data, using a one-dimensional frost heave model. The results indicate that the most likely explanation for the unexpected frost heave is a combined action of different mechanisms