摘要
高温高含冰量冻土地区,青藏铁路采取了冷却路基、降低多年冻土温度的工程措施.然而青藏铁路仍有大量路段未采用任何工程措施,因此修筑普通路基后冻土变化也是普遍关心的问题.根据青藏铁路普通路基下部土体温度监测的近期结果,分析了季节冻土区、已退化多年冻土区和多年冻土区路基下部冻土变化特征.结果表明,不同区域修筑普通路基,其下部土体温度、最大季节冻结深度、多年冻土上限等存在较大的差异.在季节冻土和已退化多年冻土区,右路肩下部(阴坡)已形成冻土隔年层;在多年冻土强烈退化区,其路基下部形成融化夹层;在高温多年冻土区,其路基下部上限存在抬升和下降,上限附近土体温度有升高的趋势.在低温多年冻土区,其路基下部上限全部抬升,上限附近土体存在"冷量"积累,有利于路基下部多年冻土热稳定性.因此,低温多年冻土区修筑普通路基后,冻土变化基本是向着有利于路基稳定性的方向发展,在其它地段修筑普通路基,冻土变化是向着不利于路基稳定性的方向发展的.特别是阴阳坡太阳辐射差异,导致了土体热状态和多年冻土上限形态产生较大的差异,这种差异将会对路基稳定性产生一定的影响.
These measures for protecting permafrost under an embankment were used to cool roadbed and lower permafrost temperature in ice-rich and warm permafrost regions along the QinghaiTibet Railway. However, not all measures can be taken in many sections of the Qinghai-Tibet Railway; therefore, the variation of permafrost under an ordinary embankment must be paid attention to after construction. In this article, the variations of soil temperatures under an ordinary embankment is analyzed in .the seasonal frozen soil regions, permafrost regions, degraded or not, using the recently monitoring data of soil temperatures under an ordinary embankment. The results show that soil temperature, maximum seasonal freezing depth and permafrost table under an embankment have some differences for different frozen soil regions after an embankment construction. In seasonal frozen soil regions and degraded permafrost regions, a frozen soil layer, which had not been thawed overall in the next year, was formed under the right shoulder of an embankment. In permafrost degradating regions, thaw sandwich was formed under an em bankment. In warm permafrost regions, permafrost table under an embankment is unstable and soil temperatures near the permafrost table have an obvious increasing tendency. In cold permafrost regions, permafrost table under an embankment is obvious increased and cool energy was accumulated in the soil near the permafrost table, which is advantage to permafrost thermal stability under an embankment. Therefore, the variation of frozen soil is advantage to roadbed stability in cold perma- frost regions; however, the variation of frozen soil is not advantage to roadbed stability in the other sections. Especially, the difference in radiation between sunside and downsun slopes of an embankment causes a difference in soil thermal regime and permafrost table, which affect potentially roadbed stability.
出处
《冰川冻土》
CSCD
北大核心
2007年第6期960-968,共9页
Journal of Glaciology and Geocryology
基金
国家自然科学基金杰出青年基金项目(40625004)
国家重点基础研究发展计划(973计划)项目(2002CB412704)资助
关键词
青藏铁路
普通路基
多年冻土变化
路基稳定性
Qinghai-Tibet Railway
ordinary embankment
variation of permafrost
roadbed stability.
