| Abstract: | One of the main construction problems in permafrost regions is protecting permafrost thermal stability. Although ventilating
ducts and crushed-rock layers were successfully used in railway embankment construction, their effects might not
meet large-width expressway requirements. The convection-intensifying composite embankment composed of perforated
ventilation ducts and crushed-rock layers was numerically studied to investigate its cooling effects. Adopting a numerical
model, the temperature fields for two kinds of composite embankment with and without air doors were analyzed considering
air flow and heat transfer characteristics in porous media. The results show that wind velocity in the crushed-rock
zone is intensified by the perforated ventilation duct. The underlying permafrost temperature obviously decreases, and the
0 °C isotherm position rises significantly due to composite embankment. The composite embankment with air doors is
more effective than that without air doors. Therefore, the new convection-intensifying composite embankment is potentially
a highly efficient cooling measure for construction in permafrost regions. |
