青藏铁路多年冻土区路基变形特征及其来源

基于青藏铁路多年冻土区34个路基监测断面2005－2011年的变形与地温资料，分析路基的变形特征及其来源。监测结果表明：①监测期累计变形量大于100 mm的断面均为普通路基，其变形主要来自路基下部因冻土上限下降而引起的高含冰量冻土的融沉变形以及融土的压密变形，其次为路基下部多年冻土因地温升高而产生的高温冻土的压缩变形。②监测期累计变形量小于100 mm的普通路基与块石结构路基断面，其变形主要来自路基下部多年冻土的压缩变形。③总体而言，块石结构路基变形量明显小于普通路基，从而验证了主动冷却措施的长期有效性。其研究结果可为冻土区路基稳定性判断及病害预警提供数据支持。

Characteristics and causes of embankment deformation for Qinghai-Tibet Railway in permafrost regions

In order to study the stability of embankment of the Qinghai-Tibet Railway after its operation, long-term monitoring system for the railway in permafrost regions was built in 2005. Monitoring content mainly includes ground temperature and deformation of the embankment. Ground temperature was monitored automatically with data collecting instrument; and deformation was obtained manually. Based on in-situ monitoring data of deformation and ground temperature from 34 embankment sections of Qinghai-Tibet Railway in permafrost regions during the year of 2005-2011, the characteristics and causes of deformation are analyzed. The results indicate that the accumulative deformation for a part of common embankments is more than 100 mm, respectively, which mainly comes from thaw settlement of permafrost with high-ice content and consolidation settlement of thawed soil because of the decline of permafrost table, as well as the compression deformation of warm permafrost due to rise of ground temperature under the embankment. For another part of common embankments and the crushed rocks embankments, owing to the compression deformation of permafrost under the embankment their total deformations are less than 100 mm, respectively. In general, the settlement deformation amount of crushed rocks embankments is remarkably less than that of common embankments, which confirms long-term effectiveness of the active cooling measure.