多年冻土区路基调查中瞬态面波勘探方法应用研究

多年冻土地区铁路路基的振动与环境变化对路基稳定性的影响问题日益突出，为了评价这种影响引起的青藏铁路多年冻土区冻土的变化状况，首次应用了一种简便、高效、环保的瞬态面波勘探方法对其天然地表和典型结构路基及其下部多年冻土层进行了勘探。试验数据良好、频散特征显著，通过反演分析得到了青藏高原多年冻土地区天然地表和典型结构路基下部土体的剪切波速度剖面和多年冻土的分布。勘探结果表明，青藏铁路北麓河试验段勘探区内多年冻土上限一般为2 m，层厚为20 m左右，多年冻土层Vs平均为600 m/s以上。该结果与该区地质钻探编录和钻孔波速测试结果较为一致，说明瞬态面波勘探在自然环境严峻的青藏高原多年冻土地区有着良好的适用性。

Application study of transient surface wave survey on embankment in permafrost regions

It’s an increasingly serious problem that the influences of vibration and environmental changes on the stability of railroad embankment in permafrost regions. The maintenance of the railroad and assessment for the influence of the railway on the permafrost requires investigation and monitoring the changes of the embankment and the permafrost layer. We firstly applied a field experiment on applicability of transient surface wave survey on natural ground and railroad embankment together with permafrost investigation. The experiment data were good and the dispersion characteristics distinct. The Vs profiles of the natural ground, embankment, and their permafrost layers underground were obtained through dispersion analysis and inversion. Moreover, the result gave very clear boundary of the table and bottom of the permafrost layer underground at the Beilu River test segment of the Qinghai-Tibet Railroad. The table of permafrost is around 2m in deep; the thick of permafrost layer is about 20m; and their average Vs are above 600m/s, which is coincident with the borehole data and wave velocity test in this area. It demonstrates that the transient surface wave survey is effective for permafrost investigation in Qinghai-Tibet plateau.