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为了解路基填筑对路基下多年冻土热状况的影响程度,在国道214沿线典型地段设置了监测断面,在天然场地路基中心、左右路肩及左右坡脚等处布设了测温孔。采用现场监测和数值模拟相结合的方法,分析了国道214沿线路基下伏多年冻土热状况长期变化情况。研究结果表明:多年冻土区修筑普通路基以后,多年冻土地温逐渐升高,路基下多年冻土发生快速融化;开始融化的时间提前,完成回冻的时间有所延后;针对K369+210断面,左路肩、路基中心以及右路肩下8m处升温速率分别为0.040,0.050,0.047℃·年-1,人为上限下降速率分别为16.82,25.36,16.73cm·年-1;在考虑全球气温升高的情况下,多年冻土温度持续升高,路基下多年冻土处于持续退化状况;年平均地温越高,人为上限下降的幅度越大;在路基运营30年内,多年冻土上限仍处于下降状态,这将严重威胁多年冻土路基的安全运行;需要及时采取措施主动冷却路基来保护冻土,避免产生更大的融沉变形,从而保障路基正常运营。
To understand the influence of roadbed filling on the thermal status of permafrost under subgrade, the monitoring section was set up in the typical section of State Road 214, and the temperature measuring holes were arranged at the center of subgrade in the natural site, the left and right shoulder and the left and right foot. Using the combination of on-site monitoring and numerical simulation, the long-term variation of the thermal status of the permafrost beneath the national highway 214 is analyzed. The results show that the permafrost temperature gradually increases after permafrost construction, and the permafrost melts rapidly under the subgrade. The thawing period begins ahead of time, and the time to complete the re-freezing is delayed. According to K369 + 210 The heating rates at the cross section, the left shoulder, the embankment center and the 8m at the right shoulder were 0.040, 0.050 and 0.047 ℃ · a-1 respectively, and the artificial upper limit descending rates were 16.82, 25.36 and 16.73cm · a -1 respectively. When considering global warming In the case of high, the permafrost temperature continues to rise, permafrost under the subgrade gradually deteriorate; the higher the annual average ground temperature, the greater the decline of the artificial ceiling; in 30 years of subgrade operation, the permafrost upper limit is still declining This will seriously threaten the safe operation of the permafrost subgrade. Timely measures should be taken to actively cool the subgrade to protect the permafrost so as to avoid greater thawing and deformation, thus ensuring the normal operation of the subgrade.