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Abstract The crushed-rock interlayer (CRI) has been used to cool the railway embankment subbase and subgrade of the Qinghai-Tibet Railway (QTR) in permafrost regions. However, in addition to the climate change, aeolian sand clogging has been affecting this mitigation techniques aimed to increase heat extraction and reduce subsurface heat penetration by air convection through the voids of the CRI. Its long-term performance is evaluated herein using a numerical modelling. Simulation results demonstrate an unclogged CRI can mitigate permafrost warming for the first 20 years with a simulated increase in average air temperature by 0.052 °C a−1. But after sand clogging, including both filling of voids in the CRI and covering of embankment slopes, its cooling performance is weakened. In such conditions, permafrost table is increasing and the permafrost is warming up under different mean annual air temperature (MAAT) of −4.5, −5.5, and −6.5 °C. The water content of the aeolian sand can also affect the cooling effectiveness of CRI. A 1 m-thick dry sand cover can induce an increase in ground temperature. But wet sand layer can mitigate and delay the effect of climate change on the permafrost degradation. The sand-control measures and additional engineering techniques should be adopted to prevent the long-term thermal stability of the QTR in sandy permafrost zone of Qinghai-Tibet Plateau. Highlights • Crushed-rock interlayer can counteract impacts of climate warming on permafrost degradation. • Performance of crushed-rock interlayer embankment declines after aeolian sand clogging. • Warm ice-rich permafrost is sensitive to climate change and aeolian sand clogging scenarios. [ABSTRACT FROM AUTHOR]

Aeolian sand is an important factor, which can affect the permafrost environment and infrastructures on the Tibetan Plateau. The thermal conductivity of aeolian sand is an important parameter for analyzing the thermal regime of the ground in cold regions. This paper presents the test results of the thermal conductivity of aeolian sand sampled from the Tibetan Plateau in unfrozen state with temperature 20 °C and in frozen state. The aeolian sand samples were measured with water content ranging from 3% to 15% and dry density ranging from 1400 to 1650 kg·m − 3 . The results show that the thermal conductivity increased with water content and dry density. Some methods that have been developed for calculating the thermal conductivity of soils are applied to predict the thermal conductivity of aeolian sand. However, these methods all have significant deviations. From the test data, a simple model is proposed as a function of the degree of saturation and the volume fraction of each phase to calculate the thermal conductivity of aeolian sand. The calculated results obtained from the proposed model agree well with the test data. The mean deviations are 2.15% and 4.28% for the unfrozen and frozen states, respectively. [ABSTRACT FROM AUTHOR]