Degradation of permafrost damages infrastructure and housing. For the sustainability of the Qinghai-Tibet Highway, a monitoring system of ground temperature under 9 typical road embankments was initiated in 1995. In this study, permafrost changes were analyzed based on the collected data until 2020. Field observations demonstrated widespread degrading of permafrost and variational features of the artificial permafrost table (APT) depths and permafrost temperature, the two important indexes for quantizing permafrost degradation. In specific, the permafrost thawing rate ranged from 5.9 to 27.5 cm yr⁻¹, and higher rates were observed for relatively warm permafrost. The warming rates of permafrost near the artificial tables varied from 0.012 to 0.044 °C yr⁻¹, while those at the depth 15.0 m varied from 0.005 to 0.022 °C yr⁻¹. Slightly higher warming rates were found for relatively cold permafrost. Importantly, a positive correlation relation was found between the permafrost thawing rate and the mean annual ground temperature at the depth of 15.0 m. The negative thermal gradient within permafrost under the embankment indicates the permafrost was degrading. The above findings may provide a valuable reference for the construction of the Qinghai-Tibet Express in the near future.

永久冻土退化会损害基础设施和住房。为了青藏公路的可持续发展，1995年启动了9个典型路堤地温监测系统。本研究根据收集的数据分析了2020年之前的多年冻土变化。现场观测表明，多年冻土和路基普遍退化。人工多年冻土层（APT）深度和多年冻土温度的变化特征是量化多年冻土退化的两个重要指标。具体而言，多年冻土融化速率范围为5.9至27.5 cm yr ^-1，相对温暖的多年冻土观察到更高的速率。人工台附近永久冻土的升温速率在0.012至0.044°C yr ^-1之间变化，而15.0 m深处的永久冻土的升温速率在0.005至0.022 °C yr ^-1之间变化。相对寒冷的永久冻土层的变暖率略高。重要的是，多年冻土融化速率与15.0 m深度的年平均地温之间存在正相关关系。路堤下永久冻土内的负温度梯度表明永久冻土正在退化。上述研究结果或可为近期青藏高速的建设提供有价值的参考。