Effect of Crushed Rock Layer Width on Natural Convection Cooling of Highway Embankment in Permafrost Regions

Abstract

For the construction of the proposed Qinghai-Tibet Express Highway in permafrost regions, it will be necessary to use the new technique of cooling the ground temperature by the coarsely crushed rock layer with a low fines content. The heat convection governing equations based on airflow function in variable permeability porous crushed rock layer are derived. Comparison of the cooling capability of winter-time natural convection in the crushed rock highway embankments with various widths of crushed rock layer and an air-permeable side slope surface were studied using a finite element method. The result indicates that the cooling capability of natural convection within the crushed rock highway embankment with a crushed rock layer width of 12 m is stronger than that with a crushed rock layer width of 10 m. Under the same temperature and pressure boundaries, the storage of cold energy in the foundation soils below the wider crushed rock highway embankment due to natural convective heat transfer is larger than that below the narrower one.