Cooling effect of a composite embankment for wide expressways in permafrost regions: a three-dimensional numerical analysis

Abstract

One of the most significant problems of wide expressway in permafrost regions is how to protect the thermal stability of permafrost under an embankment. The composite embankment consisting of perforated pipe and blocky stone has been used in the construction of common roadways. However, its effectiveness for highway is poorly concerned. Based on the cooling effect shown by the field test results of embankment with the common width, the composite embankment was investigated as a potential reasonable cooling system for embankments of wide expressways. The three-dimensional numerical model was established based on local thermal non-equilibrium theory. The temperature field characteristics were analyzed, and three main influencing factors affecting the cooling effect (different pipe diameters, blocky stone layer thicknesses and the pipe spacing) were also examined. The results show that the composite embankment works a considerable protective effect on the permafrost. Meanwhile, the increases of pipe diameter and blocky stone thickness provide an increase in cooling effect, as opposed to the increase of pipe spacing. The validity of the application of a composite embankment for wide expressways is verified and useful parameters optimized from analysis are recommended. The results may be useful in the design of embankments in permafrost regions.

Keywords:

• Composite embankment
• numerical analysis
• local thermal non-equilibrium
• perforated ventilation pipe
• permafrost

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant No. 41572255].