青藏铁路多年冻土区冻胀丘发展特征及其对路基稳定性的影响  

Development Features of Frost Mound in Permafrost Region and Their Influence on Subgrade Stability along Qinghai-Tibet Railway

作　　者：王平[1] 

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043

出　　处：《铁道标准设计》2013年第5期1-4,共4页Railway Standard Design

基　　金：国家"十一五"科技支撑计划课题(2006BAC07B02)

摘　　要：冻胀丘是多年冻土区常见的冻胀现象,冻胀丘融化后,融水汇聚或渗进路基,造成路基及其周围土体饱和,而引起路基冻胀融沉。以青藏铁路K966+746处路基右侧一典型发育的冻胀丘为研究对象,地温、水分及变形监测的结果表明:地表扰动及积水对地温及冻土上限产生了显著影响,0.5 m深度处,天然孔年平均地温低于路基坡脚处相同深度地温2.2℃,15 m深度地温低0.5℃;天然条件下的多年冻土上限为0.75 m,随着向路基方向的靠近,多年冻土人为上限逐渐加深,至路基坡脚附近上限深度为2.3 m。路基坡脚附近含水量在融化期高达60%,土体处于饱和、过饱和状态,导致地温升高和多年冻土上限的下降,从而通过侧向热侵蚀影响路基稳定性。沉降表现出冷季的冻胀和暖季的下沉,地面最大变形量约为10 cm。Frost mound is an usual frost heaving phenomenon in permafrost region. After a frost mound have melted, the melt water may converge at or sink into the subgrade, then the subgrade soil and its surrounding soil will get so saturated that the thaw settlement will appear in the subgrade. In this study, a representative frost mound at the right side of K966＋746 mileages of Qinghai-Tibet Railway was taken as an example to monitor the changes in ground temperature, moisture and the deformation. The monitoring results indicate that the ground surface disturbance and water accumulation have significant influences on the ground temperature and permafrost table： the annual mean ground temperature at 0.5 m depth in undisturbed regions is about 2.2 ℃ lower than that in toe of subgrade slope, and at 15 m depth it is about 0.5 %. The permafrost table is 0.75 m in undisturbed regions, and with the approaching to the subgrade gradually, the artificial permafrost table is gradually deeper, which is 2.3 m at the toe of subgrade slope. During thawing season, the water content is up to 60% in the toe of subgrade slope, then the soil is saturated or even supersaturated; and this will lead to ground temperature rising and permafrost table falling, consequently, the subgrade stability will be influenced by lateral thermal erosion. In addition, the settlements may appear in the form of frost heaving in cold season and in the form of sinking in warm season respectively, and the maximum ground deformation is about 10cm.

关 键 词：青藏铁路 多年冻土 冻胀丘 变形 地温 水分 

分 类 号：U213.14[交通运输工程—道路与铁道工程]