The thermal stability of roadbed in permafrost regions along Qinghai–Tibet Highway

For thoroughly understanding the roadbed failure at permafrost section of Qinghai–Tibet Highway (QTH), the radiation and thermal balance on the surface of asphalt layer of roadbed and nearby natural ground in two different types of permafrost sections were observed in two study sites located at Kunlun Mountains Pass and No. 66 Road Maintenance Station. The thermal balance on the two different surface and annual thermal rotation of the roadbed were calculated based on the data observed. It was concluded that the changes of thermal regime were the basic causes responsible for the roadbed subsidence and the formation of thawed zone. The formation and evolution processes of thawed zone in roadbed and their stability were discussed. At the end of the paper, the would-be maximum depth of the artificial permafrost table and its evaluation time as well as the final stable thickness of thawed zone below the roadbed were calculated. Based on the work, feasible measures to rehabilitate the QTH were put forward.