Abstract: Crushed rock embankments embedded a perforated ventilation pipe are employed in the expressway construction of the Qinghai-Tibet Plateau. Laboratory experiments for the cooling effect in crushed rock embankment samples with air-open/air-tight surfaces embedded a perforated ventilation pipe are performed. Impacts of air-open/air-tight top boundaries on the cooling effect in crushed rock embankment embedded a perforated ventilation pipe are analyzed. The analysis shows that the air-open/air-tight crushed rock embankments embedded a perforated ventilation pipe can enhance the cooling capability of the embankment base due to forced convective heat transfer of the pore air motion in the crushed rock region near the ventilation pipe forming a pore air circulation in conjunction with the ambient air by the small holes of ventilation pipe wall, and the natural convective cooling effect due to pore air circulation may occur in the upper region of the crushed rock embankment during the negative air temperature ventilating period. Hence, the cooling effect in the air-tight crushed rock embankment embedded a perforated ventilation pipe is significant due to ventilating during the negative air temperature fluctuation period.

Key words: crushed rock embankment, perforated ventilation pipe, air-open boundary, air-tight boundary, cooling effect