Numerical Investigation of the Temperature Field of a New Convection-Intensifying Composite Embankment in Permafrost Regions

One of the main problems of wide expressway construction in permafrost regions involves protection of the thermal stability of roadbed. Although ventilating ducts and crushed-rock layers have been successfully used in railway embankment construction, their effects may fail to reach the requirements of large-width expressways. This paper proposes Convection-intensifying composite embankments composed of perforated ventilation ducts and crushed-rock layers and numerically studied their cooling effects. A numerical model for composite embankments in permafrost regions is established considering air flow and heat transfer characteristics in porous media. Temperature fields and cooling effects are simulated, and the results show that when the underlying permafrost temperature decreases, the position of the 0°C isotherm increases significantly. The installed position of the ventilation duct and the thickness of crushed-rock layer have a significant influence on thermal status of the underlying permafrost. The new convection-intensifying composite embankment is a potential cooling measure for high-grade, large-width highway construction in permafrost regions.