Monitoring study on technology of the cooling roadbed in permafrost region of Qinghai–Tibet plateau

On the base of in situ engineering tests of the crushed rock embankment, the embankment of crushed rock slope protection and the ventilated duct embankment in Qinghai–Tibet railway, the basic data of actively adjusting and cooling roadbed measures in permafrost regions have been obtained through monitoring the ground temperature in the roadbed. Analyzing the data of two freezing and thawing periods, the three measures all have certain effects of adjusting and cooling roadbed, and are advantageous to protecting permafrost under the roadbed. However, during 2–3 years after construction, the rising of artificial permafrost table still need consuming the cold energy of underground frozen soil, the thermal regime of permafrost is in instable phase.