青藏铁路高填方路基对下伏多年冻土热状况的影响

EFFECT OF HIGH EMBANKMENT ON THE THERMAL REGIME OF UNDERLYING PERMAFROST IN QING-ZANG RAILWAY

基于青藏铁路北麓河试验段两个监测断面的地温监测资料 ,分析了修筑高路基后下伏土层的热状况变化特征。结果表明 ,修筑高路基后 ,多年冻土上限有所抬升 ,而下伏土层地温明显升高。多年冻土上限的抬升主要是由于高路基的热阻效应导致上限附近土层温度变幅急剧减小而形成的。高路基的修筑会引起路基阴阳面热交换状态的明显差异 ,路基阳面边坡是最强烈的吸热面 ,而路基阴面边坡表现为放热效应 。

Based on observed data of two monitoring sections in Beiluhe test site of Qing-Zang Railway, The characteristics of underlying ground thermal regime after constructing high embankment are analyzed. Results indicated that permafrost table was raised, the underlying ground temperature increased after constructing embankment. The rising of permafrost table should be attributed to an obvious decrease in fluctuation of temperature at the depth of permafrost table due to the thermal resistance effect of high embankment. Constructing high embankment may cause considerable difference in thermal regime between shade slope and sunshine slope of embankment. The sushine slope is the most violent heat-absorb surface, while the shade slope presents as a heat-discharge surface. As a result, the thawing extent of underlying permafrost may differ.