Abstract: Laboratory experiments on the cooling capability of crushed rock embankment samples with a perforated ventilation pipe and an air permeable top surface are performed. The impact of mechanism on the cooling capability of the open crushed rock embankment enhanced by a perforated ventilation pipe is analyzed. The analysis indicates that the heat transfer processes in the crushed rock embankment with a perforated ventilation pipe and an air permeable surface include pure heat conduction, forced convection due to the pore air motion in the crushed rock layer forming directly a complete circulation in conjunction with the ambient air by the small holes of the perforated ventilation pipe wall, convective heat transport between the ambient air and the surface of pipe wall, and forced convection that occurs in the crushed rock layer around the perforated pipe forming directly a pore air circulation in conjunction with the ambient air by the small holes of perforated pipe wall. Under the air permeable top surface and only ventilating during the negative temperature period, a crushed rock embankment embedded a perforated ventilation pipe may enhance the cooling capability of the embankment base due to winter-time air motions in the crushed rock layer forming a complete pore air circulation in conjunction with the ambient cold air via the small holes of perforated pipe wall and the air permeable top surface.

Key words: crushed rock embankment, air permeable surface, perforated ventilation pipe, cooling capability, enhancement