Thermal control performance of the embankment with L-shaped thermosyphons and insulations along the Gonghe-Yushu Highway

Abstract

In permafrost regions, the climate warming and construction of engineering will change the energy exchange process between the original ground surface and the ambient, and warm the permafrost stratum. The degradation of permafrost stratum will endanger the stability of the infrastructures built on it. To protect permafrost from degradation, the embankment combined with L-shaped thermosyhons and insulations was adopted in the construction of the first high-grade highway in permafrost regions of the Qinghai-Tibet Plateau, namely the Gonghe-Yushu Highway. In this study, we field investigated the energy budget process of the embankment. The results indicated that the embankment can efficiently cool the warm permafrost stratum under the embankment in cold seasons. The net annual energy budget can reach approximately 1117 MJ. The composite embankment can cool the deep ground (13.0 m below the pavement layer) with the average speed of about 0.02 °C/year in the first few years. Meanwhile, it can adjust the asymmetric geotemperature distributions under two slopes. Thus, the long-term service performance of the embankment will be significantly improved. It is expected that the research can supply support for the design and construction of other high-grade highways in permafrost regions by reasonably using natural cool energy to protect permafrost foundation.