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利用青藏公路多年冻土区温度的监测资料,分析了高温冻土区普通路基下冻土的热状态及其人为上限的演变特征,并与自然地表下的变化特征进行对比。结果表明:1)沥青路面近地表温度年增幅明显大于自然地表的温度年增幅;2)与自然地表下相比,沥青路面下深部(h>6m)土体具有较小的温度梯度,对外界热扰动敏感;多年冻土温度逐年升高,不利于路基的长期稳定;3)高温冻土路基下浅部土体,冻结期明显小于融化期。融化期时间提前至3月底4月初,而冻结期开始时间与自然地表下均为11月底;融化深度大于冻结深度;4)沥青路面下多年冻土人为上限逐年下降,下降速率快于多年冻土天然上限下降速率,并且在多年冻土顶板上部已经形成贯通的融化层,融化层厚度逐年加厚。
Based on the monitoring data of permafrost zone temperature in Qinghai-Tibet Highway, the evolution of permafrost thermal regime and its artificial upper bound under common embankment in high permafrost area is analyzed and compared with the variation characteristics under natural ground surface. The results show that: 1) The annual increase of near-surface temperature of asphalt pavement is obviously larger than the annual increase of temperature of natural surface; 2) Compared with the subsurface subsurface, the soil depth of h> 6m under asphalt pavement has smaller temperature gradient, The temperature of permafrost is increasing year by year, which is unfavorable to the long-term stability of subgrade. 3) The soil in the shallow part of subgrade under high temperature permafrost is obviously less thawing than the thawing period. The thaw period advanced to the end of March and the beginning of April and the beginning of the freezing period and the natural surface were at the end of November; the thawing depth was greater than the freezing depth; 4) The artificial upper limit of permafrost under asphalt pavement decreased year by year, Natural maximum rate of decline, and in the upper part of the permafrost has been formed through the melting layer, the thickness of the melting layer thicker year by year.