Dynamic thermal regime of permafrost beneath embankment of Qinghai-Tibet Highway under the scenarios of changing structure and climate warming

Abstract

Stability of the embankment is largely concerned with the height and pavement type in permafrost area. Climate is another key factor. The heat transfer model with phase change and finite element method are used to simulate the thermal regime of permafrost beneath embankment of Qinghai-Tibet Highway, considering the changing of pavement type, height of embankment and climate warming since the building of the road was started in 1954. In-situ observation of ground temperature was performed. Simulated results indicate that increasing embankment height can decrease the depth of permafrost table temporarily, and then the permafrost table goes deeper soon. Heat absorbing of black pavement is a key factor that causes permafrost degradation beneath the embankment. Both the simulated and the measured results indicate a continuous trend of permafrost degradation beneath both the embankment and the natural ground under the scenario of climate warming, which implies that only increase the embankment height is not enough to keep it stable.