An active layer detachment slide (ALDS) in the interior portion of the Qinghai-Tibet Plateau (QTP) was investigated within 2 days of its formation on September 21, 2018. The ALDS developed on a relatively gentle slope (4.8 to 9 ) at an elevation of 4,850 m above sea level (asl) and was about 145 m long and 45 m wide, with a headscarp 2.2-2.5 m high. Analyses of meteorological data and soil temperatures indicated that it was probably triggered by a record thaw depth which intersected a layer with high ice content at the base of the active layer and in the top of the permafrost. Based on the time window, the minimum downslope velocity of the main slide mass was about 20 m/h which is higher than previously reported values. The ALDS ran into the embankment of the Qinghai-Tibet Railway (QTR) but did not damage the railbed. However, extensive rehabilitation of the slope was needed subsequent to the failure to clear the slide mass and as minor headscarp recession and thaw settlement continued on the slope. In this work, we describe this feature and the most likely mechanisms of development.

Understanding the long‐term role of cooling the underlying permafrost of the crushed rock structure embankment (CRSE) along the Qinghai–Xizang Railway (QXR) is crucial for the railway's safe operation. The thermal regime of the permafrost under the CRSE is analyzed here using monitoring data of soil temperature from 2005 to 2015. The results show that the CRSE plays an important long‐term role in cooling the underlying permafrost under the present climate change conditions; however, different types of CRSEs have different cooling effects. A U‐shaped crushed rock embankment and a crushed rock berm embankment with debris rock revetment can maintain the cooling of the permafrost underlying the embankment under a future climate warming of 1.0°C. Moreover, under an increase in air temperature of 0.5°C, a crushed‐based rock embankment and a crushed rock revetment embankment can maintain the cooling of the underlying permafrost when its mean annual ground temperature is below −1.0°C. The long‐term role of cooling the underlying permafrost of CRSEs indicates that the QXR must use reinforcing engineering techniques to ensure its safe operation and adaptation to a temperature increase of 1.5°C.

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