Cooling Performance of a Composite Embankment for High-Grade Highways in Permafrost Regions

Abstract

In permafrost regions, high-grade highways with a wide and dark-colored asphalt pavement can cause the degradation of underlying permafrost. However, the embankments with single commonly cooling technique, e.g. two-phase closed thermosyphon (TPCT) embankment and crushed-rock embankment cannot effectively solve the problem. Therefore, a composite embankment for high-grade highways, combined with L-shaped TPCTs, crushed-rock revetments and insulation was designed. The L-shaped TPCTs were used to cool the core of the embankment, the crushed-rock revetments with different thicknesses was intended to cool the side slopes and to diminish the sunny-shady slope effect, and the insulation was designed to strengthen the cooling effect by increasing the thermal resistance of the embankment. Here, we experimentally and numerically evaluated the cooling performance of the composite embankment. The results indicate that the composite embankment can effectively raise the permafrost Table (0 °C isotherm) and cool the underlying permafrost under a separated high-grade highway with a wide and dark-colored asphalt pavement (double lanes each direction). Therefore, the composite embankment structure should be considered to be applied to the construction of high-grade highways in permafrost regions.