Effect of sunny-shady slopes and strike on thermal regime of subgrade along a high-speed railway in cold regions, China

Ground temperature and deformation of embankment were monitored at typical sections of the Harbin-Qiqihar high speed railway (HSR) to investigate complex causes of differential embankment deformation due to sunny-shady slopes and route strike in cold regions. Maximum frozen depth, ground temperature, frost heave, and thaw settlement of the embankment in the sunny and shady sides were analyzed relative to measurement dates, and then a numerical model for the embankment temperature filed was also established. On these bases, the influence of route strike on the embankment thermal regime and its mechanism were then revealed; and proper engineering countermeasures were proposed to mitigate the transverse embankment thermal difference; the formation mechanism of the differential deformation due to sunny-shady slopes was discussed. The results showed that both temperature and maximum frozen depth of the sunny side were greater than the shady side, whereas the cumulative frost heave of the sunny side was less than the shady side with opposite trends found for the cumulative thaw settlement. The temperature difference between the sunny and shady shoulders decreased gradually with increasing strike angle. The findings are potentially helpful for better understanding differential embankment deformation in cold regions, as well as for improving HSR embankment quality and operational safety.