Climate warming is likely to weaken the performance of two-phase closed thermosyphon on the Qinghai–Tibet Plateau

Abstract

Over the years, numerous geotechnical approaches have been implemented to mitigate the adverse effects of climate warming on various infrastructures in the permafrost region of the Qinghai–Tibet Plateau (QTP), such as the Qinghai–Tibet Highway and Railway, and achieved the expected engineering outcomes. However, little attention has been given to whether the performance of these geotechnical approaches has changed during the ongoing process of climate warming. To investigate the performance variation of one of these geotechnical approaches, which is two-phase closed thermosyphon (TPCT), during sustained climate warming, we conducted a statistical analysis of soil temperature monitoring data in 2003–2020 from eight regular embankments and six TPCT embankments in our permafrost monitoring network. The results indicate that TPCT undeniably has a cooling effect on the permafrost beneath embankments, even rapidly eliminated previously formed taliks beneath embankment. However, further analysis reveals that the performance of TPCT has been weakening during sustained climate warming, which has confirmed by the re-forming of the taliks beneath embankment where they had been previously eliminated. Based on the current understanding, we attributed the weakening of thermosyphon performance to a significant reduction in the air temperature freezing index caused by ongoing climate warming. Through this study, we aimed to draw attention to the evolving performance of geotechnical approaches in permafrost regions amid climate warming, prompting necessary engineering innovations to address this situation and ensure the sustainable development of the permafrost region on the QTP.