高温不稳定多年冻土区保温护道路基热状况监测分析

Monitoring and analysis of the thermal condition of insulation protection roadbed in high-temperature unstable permafrost region

基于高温不稳定多年冻土区保温护道路段地温监测数据,分析了天然场地及左右路肩下地温、年平均地层温度、热收支及多年冻土上限变化等,探讨了气候变暖及阴阳坡效应下路基不同位置不同深度热状态变化特性及其与天然场地的差异。结果表明:左右路肩阴阳坡效应显著,左路肩下多年冻土最大融化深度为右路肩的2倍,最大融化深度降低速率为右路肩的5倍,且左路肩下多年冻土上限下降速率为右路肩的1.5倍;右路肩处在阴坡且保温护道可能对其多年冻土维持稳定起到了一定积极作用,抬升了其人为冻土上限并减缓了上限下降速率。不同位置年平均地层温度均呈上升趋势,且增长速率随深度逐渐降低,然而左路肩的路基与天然场地交界面附近温度增长速率大于2.5 m深度处,表明此特殊位置土层在多因素作用下可能受到更强的热扰动影响。一般情况下,冻土吸热放热量均随深度降低逐渐减少,但多年冻土上限处在0℃等温线的特殊位置,可能出现吸热量突然增大的现象;多年冻土上限处由于深度较深,热收支增长速率已不受阴阳坡效应影响,该断面左路肩多年冻土上限处年平均热收支为右路肩的2.92倍,但其热收支增长速率几乎相等。

The analysis of ground temperature monitoring data from the road section with thermal insulation protection measure in the high-temperature unstable permafrost region provides valuable insights into the temporal changes in ground temperature under natural conditions and on the left and right shoulders of the roadbed.This study encompasses the examination of mean annual ground layer temperature,heat budget,and permafrost table variations.Furthermore,the influence of climate warming and the sunny-shady slope effect on the thermal state change characteristics at various locations and depths of the roadbed,as well as the differences between these characteristics and the natural site,are also explored.The results of the study indicate that the sunny-shady slope effect on the left and right shoulders is particularly pronounced.Specifically,the maximum thawing depth of permafrost under the left shoulder is found to be twice that of the right roadbed shoulder.The rate of reduction of the maximum thawing depth is five times that of the right shoulder,and the declining rate of the permafrost table under the left shoulder is also 1.5 times that of the right shoulder.These findings suggest that the thermal state of the left and right shoulders is significantly different under the influence of the sunny-shady slope effect.Additionally,the right shoulder,being situated on a shady slope,may have experienced a stabilizing effect on the permafrost due to the presence of the insulation protection.This is evidenced by the fact that the artificial permafrost table on the right shoulder has been raised.This positive role of the insulation protection in stabilizing the permafrost is crucial for maintaining the integrity of the roadbed in the high-temperature unstable permafrost region.Furthermore,the study reveals that the mean annual ground layer temperature at different locations exhibits an upward trend.This growth rate gradually decreases with the increase in depth.However,it is observed that near the interface between the roadbed and the natural site on the left shoulder,the temperature growth rate is greater than that at a depth of 2.5 meters.This suggests that in this specific location,the soil layer may be subjected to stronger thermal disturbance under the influence of certain factors.To further understand the thermal state changes in the roadbed,a comprehensive analysis of the ground temperature monitoring data is conducted.This analysis involves examining the temporal variations in mean annual ground layer temperature,heat budget,and permafrost table.By comparing these parameters under natural conditions and on the left and right shoulders of the road,valuable insights into the impact of climate warming and the sunny-shady slope effect can be gained.The study also investigates the differences in thermal state change characteristics between the roadbed and the natural site.This includes analyzing the variations in maximum thawing depth and permafrost table declining rate.By quantifying these differences,a clearer understanding of the influence of the sunny-shady slope effect on the thermal state of the roadbed can be obtained.Furthermore,the study explores the role of the insulated berm in stabilizing the permafrost on the right shoulder.This involves analyzing the changes in the artificial permafrost table and the declining rate.In conclusion,the analysis of ground temperature monitoring data from the thermal insulation and protection roadbed section in the high-temperature unstable permafrost region provides valuable insights into the temporal changes in ground temperature under natural conditions and on the left and right shoulders of the roadbed.The study highlights the significant influence of the sunny-shady slope effect on the thermal state of the roadbed,particularly on the left shoulder.Additionally,the positive role of the insulation protection in stabilizing the permafrost on the right shoulder is emphasized.These findings contribute to a better understanding of the thermal dynamics in the roadbed and provide valuable information for the design and maintenance of roadbed in high-temperature unstable permafrost regions.