Winter-time convection in open-graded embankments

摘要: Abstract Winter-time natural convection in open-graded gravel embankments is studied using a numerical representation of the unsteady two-dimensional momentum and energy equations. The analysis examines ability these to maintain structural integrity thaw-unstable permafrost that often underlies roadway or airport northern climates. As result low ambient temperatures acting on embankment surface during winter months, an unstable density stratification develops embankment. Buoyancy-driven pore air occurs reaction gradient. enhances upward transport heat out thus cooling lower portions underlying foundation soil. During summer months stable does not occur. Consequently, summer-time transfer dominated by thermal conduction which transports less effectively. results present study show winter-time can soil beneath as much 5°C annual average basis compared stan0ard sand embankments. Time varying velocites are calculated for different embankmenkt permeabilities visualized form isotherm velocity vector plots times year.