In the context of climate warming, damage to road pavements and embankments in permafrost regions caused by thawing of underlying permafrost severely reduces the serviceability of roads. In this study, 10 types of asphalt pavement damage were measured every kilometer along the Qinghai–Tibet Highway (QTH), from Kunlun Mountain to Tonggula Mountain (approximately 440 km in permafrost regions). Based on observed data and embankment geometry along the QTH, and information about the characteristics of the permafrost, aspects of pavement deterioration are analyzed and discussed. The three most common forms of pavement damage in the permafrost regions are transverse cracking (TC), potholes, and longitudinal cracking (LC), observed in 87, 64, and 57% of the study section, respectively. About half of the damaged pavement was also affected by block cracking (BC) and alligator cracking (AC), in addition to LC and TC. Results also showed that pavement damage in the degrading permafrost regions was closely related to the underlying permafrost characteristics and embankment geometry. Damage from settlement and patching were more severe in sections with high ice content than low ice content. All the above forms of damage increase exponentially with higher underlying permafrost temperatures. Because of the significant thermal effects of sunlit/shaded slopes, BC, LC, and TC cracking is closely related to roadway orientation, with the most severe cracking damage observed in roads oriented approximately east to west (E–W). Also, more LC was seen in sections of greater embankment thickness, which exacerbates the sunlit/shaded thermal effect.

Most previous studies of the Qinghai-Tibet engineering corridor (QTEC) have focused on the impacts of climate change on thaw-induced slope failures, whereas few have considered freeze-induced slope failures. Terrestrial laser scanning was used in combination with global navigation satellite systems to monitor three-dimensional surface changes between 2014 and 2015 on the slope of permafrost in the QTEC, which experienced two thawing periods and a freezing period. Soil temperature and moisture sensors were also deployed at 11 depths to reveal the hydrological–thermal dynamics of the active layer. We analyzed scanned surface changes in the slope based on comparisons of multi-temporal point cloud data to determine how the hydrological–thermal process affected active layer deformation during freeze–thaw cycles, thereby comprehensively quantifying the surface deformation. During the two thawing periods, the major structure of the slope exhibited subsidence trends, whereas the major structure of the slope had an uplift trend in the freezing period. The seasonal subsidence trend was caused by thaw settlement and the seasonal uplift trend was probably due to frost heaving. This occurred mainly because the active layer and the upper permafrost underwent a phase transition due to heat transfer. The ground movements occurred approximately in the soil temperature conduction direction between the top of the soil and the permafrost table. The elevation deformation range was mainly −0.20 m to 0.20 m. Surface volume increases with heaving after freezing could have compensated for the loss of thawing twice and still led to the upward swelling of the slope. Thus, this type of slope in permafrost is dominated by frost heave. Deformation characteristics of the slope will support enhanced decision making regarding the implementation of remote sensing and hydrological–thermal measurement technologies to monitor changes in the slopes in permafrost adjacent to engineering corridors, thereby improving the understanding and assessment of hazards.

Temperature changes and deformations were monitored on various embankment types on the Qinghai-Tibet Railway. Some of these embankments utilized permafrost protection techniques such as duct ventilation, crushed-rock embankments, crushed-rock protected slopes, or thermal-insulation treatments. Some embankments were built conventionally without considering permafrost protection. It was found that the majority of the deformations on both the permafrost-protected and the conventionally built embankments were due to deformation of warm frozen layers closely related to the temperature changes in the underlying permafrost. However, it was found that building embankments with permafrost protection reduced the magnitude of the settlements. After 2–3 years , deformation of all the embankments with permafrost protection countermeasures became smaller and smaller, whereas deformation was still increasing in the conventional embankments, where the settlement in the underlying permafrost could reach a considerable lev...