Experimental and numerical investigation on the sunny-shady slopes effect of three cooling embankments along an expressway in warm permafrost region, China

Subgrade diseases caused by temperature differences of sunny-shady slope seriously threaten the safe operation of highways or railways in permafrost regions. This study analyzes the transverse thermal characteristics of different soil layers for three different cooling embankments based on temperature data collected from the newly constructed Gonghe–Yushu Expressway. The complex causes of differential temperature fields in warm permafrost regions are then investigated. Three-dimensional heat transfer models are established for each cooling embankment and used to predict the long-term transverse thermal characteristics of the embankments. On the basis of the study, optimized engineering measures are proposed to mitigate the transverse ground temperature difference between the slopes. Results demonstrate that the temperature differences between the sunny and shady sides for all three cooling embankments are greater than 0 °C. The underlying permafrost displays a warming trend which can be understood to be increasing under the effect of climate warming. Ventilated embankment with insulation and crushed rock proved the most effective in decreasing transverse thermal differences. These findings provide important technical references for the future construction and operational safety of expressway in warm permafrost regions. •Complex causes of differential temperature field of embankment are investigated.•Three-dimensional heat transfer models for different embankments were established.•Short-term and long-term transverse thermal regimes of embankments were studied.•VE + insulation + crushed-rock was the greatest effect in decreasing thermal difference.