In Situ Test on Cooling Effectiveness of Air Convection Embankment with Crushed Rock Slope Protection in Permafrost Regions

摘要

An experimental air convection embankment (ACE) was constructed in Beiluhe on the Qinghai-Tibet Plateau during 2001-2003, using coarse (5-8 and 40-50 cm), poorly graded crushed rock fill material on the slope of embankment with thick ground ice permafrost foundation, which should be called the air convection embankment with crushed rock slope protection (ACE-CRSP). The highly permeable ACE-CRSP installation was designed to test the cooling effectiveness of ACE-CRSP concept in an actual railway project. Ground temperature data were collected from test sections on the railway with thermistor sensor strings. The results showed that the mean ground temperature under the layer of the crushed rock with coarse particle diameter of 40-50 cm was lower than that under one with finer particle diameter of 5-8 cm, and the fluctuating range of temperature under the former was bigger than that under the latter. It was obvious that the maximum thaw depth was raised under the layer of crushed rock with coarse particle diameter of 40-50 cm, which resulted from the stronger cooling effectiveness of air convection during the winter. The amount of heat exchange also showed that the absorbed cooling energy of the foundation, under the layer of the crushed rock with coarse diameter, was larger than that with finer diameter. So, we believe that the cooling effectiveness of the crushed rock layer with coarse diameter was stronger than that one with finer diameter.