Optimizing embankment structures in a snowy permafrost region of the pan-Arctic based on a coupled numerical model

In pan-Arctic permafrost regions, snow drift may lead to more snow accumulation around the road, which prevents the heat release from the underlying soil in winter and aggravates the permafrost degradation beneath the road. However, the study of snow distribution patterns around the road is insufficient, which makes it difficult to accurately evaluate the long-term stability of the road. To investigate the thermal regime of the road and optimize the road structure in permafrost regions under the effect of snow drift, based on heat transfer and multiphase flow theories, a coupled numerical model is presented. The model includes snow transportation around the embankment, natural convection of air in the crushed-rock layer, and heat conduction in soil and snow layers. The results of model simulation show that an embankment with a height of 4 m leads to heavier snow accumulation on both sides of the embankment in winter compared to an embankment with a height of 3 m, which accelerates permafrost degradation. The full crushed-rock embankment with a height of 3 m can be used to counteract the permafrost degradation caused by snow accumulation to some extent, while the soil temperature beneath the toe of the embankment slope is still noticeably higher. By contrast, when the U-shaped crushed-rock embankment (UCRE) with a height of 3 m and 1:6(vertical: horizontal) side slopes is used, the snow accumulation around the embankment is greatly reduced, the embankment slope delivers better cooling performance. Considering the climate warming at a rate of 0.067 ℃ year−1 in pan-Arctic regions, the thermal stability of the UCRE can still be ensured after 20 years of its construction. These results provide a valuable reference for road construction in pan-Arctic snowy permafrost regions.