Investigating the mechanism of frost penetration under railway embankment and projecting frost depth for future expected climate: A case study

• Published in: Cold regions science and technology 2022-05, Vol.197, p.103523, Article 103523
• Main Authors: Roustaei, M., Hendry, M.T., Roghani, A.
• Format: Article
• Language: English
• Subjects: Climate models; Frost penetration depth; Frost susceptibility; Railway subgrade; TEMP/W; Weather conditions
• ISSN: 0165-232X; 1872-7441
• DOI: 10.1016/j.coldregions.2022.103523

A common issue for railways constructed in cold regions is the development of localized frost heave on the surface of railway tracks during winter and track softening during the spring thaw. Both frost heave and thaw softening cause track geometry degradation and often require frequent maintenance and the reduction of train speeds to ensure safe operating conditions. This study investigated the mechanism of frost development within a railway embankment through field observations and numerical simulations. This paper uses the temperature measurements from an instrumented section of railway track in Ontario, Canada to calibrate a numerical model and then uses this model to quantify the effect of ambient temperature and the amount of snowfall on the frost penetration within railway foundations. The results show a widespread frost zone develops within the embankment that could last until spring. The sensitivity analysis conducted as part of this study shows ambient temperature has a stronger effect on frost penetration than snow on the ground. Moreover, this paper proposes a simplified methodology to combine numerical model results and data from climate models to project future frost depth at a given location. The application of this methodology at the study site of this project indicated the frost will penetrate less under future climate but still to sufficient depths to reach the frost-susceptible layers of subgrade. •Thicker snow cover maintains higher mean annual ground temperatures and shallower frost penetration depths.•The effect of snow cover reduced due to the thermal conductivity and microstructural changes after being compacted.•A widespread frost zone develops in the embankment in winter, lasts until May and result in less proper support of the tracks•Ambient temperature has a stronger effect on frost penetration than snow on the ground.•More rainfall could result in higher volumetric water content, more required energy for phase change and a shallower frost depth.•The maximum frost depth of the next 75 years at this site were anticipated using a regression model and a climate model.