Abstract

Permafrost degradation caused by climate warming and human activities would result in the thermal instability of embankments in permafrost regions, which would increase the maintenance cost. Two-phase closed thermosyphon (TPCT) is a widely-accepted green countermeasure against the problem in permafrost regions. However, the combination of TPCT with other countermeasures is usually proposed when it comes to a high-grade highway with a wide pavement. In order to explore the ideal combination, four combinations are compared by the instrumented physical embankment models: 1) inclined TPCT and insulation; 2) inclined TPCT, insulation and crushed-rock revetment; 3) L-shaped TPCT and insulation and 4) L-shaped TPCT, insulation and crushed-rock revetment. Under this experimental condition, the experimental results show that the TPCTs can effectively cool down the embankment center, the crushed-rock revetments can keep the soil slope and slope toe frozen during the whole freeze-thaw period after the 5th cycle, and the insulation can effectively prevent heat from entering into the embankment in warm seasons. After a thorough comparison of the thermal distribution and heat flux during seven freeze-thaw cycles, the embankment combined with L-shaped TPCT, insulation and crushed-rock revetment is proved to be the best way to keep the thermal stability of the wide-paved embankment. The results have potential to use for the future optimal construction against the thermal instability of high-grade highways in permafrost regions.

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