Analysis on effect of permafrost protection by two-phase closed thermosyphon and insulation jointly in permafrost regions

Warm and ice-rich permafrost is widely distributed along the Qinghai–Tibetan railway, which is very sensitive to the environmental change. To protect the permafrost from thawing, we have suggested the combination of thermal-insulation and two-phase closed thermosyphon. In this paper, a three-dimensional numerical analysis for the temperature characteristic of the common embankment, an embankment with insulation, the embankment with two-phase closed thermosyphon, as well as the embankment protected by the combination of both insulation and thermosyphon have been performed considering the case where the air temperature will increase by 2.0 °C in the next 50 years. The numerical results indicate that in the fist three cases permafrost will (considerably) degrade where the yearly average air temperature is − 3.5 °C, or the yearly average temperature on the natural ground is − 1.0 °C. However, when protected by the combination of insulation and thermosyphon much better protection on the permafrost can be expected. The influence of annual range of air temperature and thermosyphon performance on the effect of permafrost protection was also analyzed.