Numerical evaluation of thermal stability of a W-shaped crushed-rock embankment with shady and sunny slopes in warm permafrost regions

Abstract

The crushed-rock interlayer structure, crushed-rock revetment, and insulation board have been successfully applied in low-grade highways in low-temperature permafrost regions. However, it is doubtful whether the composite structure of the W-shaped crushed-rock embankment (W-CRE) composed of the three measures can be applied to high-grade highways in warm permafrost regions. For this reason, a model coupled with water, heat, and deformation in unsaturated soil was established for the high-grade highway with the W-CRE in warm permafrost regions. The cooling effect of the composite structure on the embankment with shady and sunny slopes in 20 service years was evaluated by numerical calculation, and the unfrozen water distributions and deformation characteristics were analyzed. The results show that (1) the W-CRE can cool the embankment of the high-grade highway in warm permafrost regions and improve the asymmetric ground temperature distributions caused by the shady and sunny slopes. (2) the W-CRE can improve the asymmetry of unfrozen water distributions, reduce the uneven settlement, and thus improve the mechanical stability of the embankment. (3) Although the cooling mechanisms of the three measures are different, the complementary thermal regulation mechanism formed by them in the composite structure effectively improves the thermo-mechanical stability of the embankment.