Cooling performance of novel embankment structures in permafrost regions

Objective This study investigated the cooling performance and permafrost protection effect of different embankment structures. It verified the engineering adaptability of embankment structures, improving the road service performance. Method In-situ measurements were conducted on three novel embankments with thermosyphon-ventilation plate, thermosyphon-insulated plate, and ventilation plate at Erzhi highway test site in Qinghai Province. The cooling performance and pavement settlement characteristics of three types of embankment structures were compared. Result All three embankments effectively reduce embankment temperature, maintaining permafrost embankment stability. From the perspective of cooling effect, the embankment with thermosyphon-ventilation plate has the lowest temperature throughout borehole depth. The longest freezing period of embankment center reaches 6 months. Thermosyphon-ventilation plate shows significant cooling performance. Its 0 ℃ isotherm rises by up to 1.7 m during monitoring; the average temperature of embankment decreases by 6.6 ℃, achieving the best cooling performance. The embankment with thermosyphon-insulated plate has the smallest temperature difference between warm and cold seasons. The settlement deformation reduces by 49.0 mm compared with that with thermosyphon-ventilation plate, improving pavement smoothness. The embankment with ventilation plate is in an open state, limiting its cooling performance. Among three structures, the embankment with thermosyphon-ventilation plate would effectively prevent permafrost degradation. The embankment with thermosyphon-insulated plate would stabilize ground temperature and slow permafrost degradation. The embankment with ventilation plate has limited effect on slowing permafrost degradation. Conclusion Considering cooling efficiency and engineering applicability, the composite embankment with thermosyphon-ventilation plate is recommended for cold-region roads and permafrost maintenance.