Application of the cooling measures in the highway roadbed in permafrost regions of the Qinghai-Tibet Plateau

Permafrost in the Qinghai-Tibet Plateau (QTP) accounts for a total area of 1.05 x 106 km2. Many highway engineerings have been through the permafrost regions of the QTP, including the Qingkang Highway (QKH), Qinghai-Tibet Highway (QTH), and Gonghe-Yushu expressway (GYE), and the Qinghai-Tibet expressway (QTE) will be constructed in the future. Under the action of roadbed construction and global warming, permafrost under roadbed is degraded and causes serious pavement damage. Although many useful cooling measures have been applied to prevent permafrost degradation, their application presents significant challenges on account of the stronger endothermic action of asphalt pavement. This paper summarizes the working principle of existing cooling measures, and ascertains the relationship between pavement damage and ground temperature distribution of permafrost under roadbed. Based on the relationship, geotemperature distribution criteria and requirements for the cooling measures are proposed, and some suitable composite structures and measures are suggested. The results reported in this paper can provide a valuable guidance for the design and construction of the QTE in the future.