高寒冻土区路基变形演化规律与破坏特征
Evolution laws and failure characteristics of subgrade deformation inalpine permafrost region

为进一步研究高寒冻土区路基变形破坏演化过程,以漠北公路K6+200断面处的高温高含冰量冻土区路基和K8+200断面处的低温高含冰量冻土区路基为研究对象,在路基不同部位和路基下不同深度处土体埋设温度传感器和变形传感器,研究了高纬度、高寒冻土区不同冻土条件下路基实测温度和变形演化过程及其特征。研究结果表明:在高温高含冰量冻土区,在公路建成2年后,路基下出现了明显的融化盘偏移现象,新建宽幅路基呈现出明显的横向不均匀变形特性,路基下形成了2个融化盘,其中一个明显向路基坡脚处偏移,左坡脚和路中冻土上限明显下降了3～4 m,路基下原天然地表处沉降达4～9 cm,而路肩处冻土上限基本保持稳定; 在低温高含冰量冻土区,在保证一定路基高度的条件下,除了建成初期路基土体存在一定的变形(工后沉陷)外,由路基下多年冻土不均匀融化导致的变形很小,因此,在低温冻土区公路路基稳定性相对较好。可见,研究结论进一步阐释了高温冻土区路基、路面变形严重的成因,为高纬度、高寒冻土区路面结构抗融沉破坏设计和病害防治提供了参考,揭示了高温多年冻土区路基纵裂、沉陷等不均匀变形破坏的特征和成因,相比高温多年冻土区,在保证一定路基高度下低温多年冻土区路基具有相对良好的稳定性,这一结论对于高纬度、高寒冻土区不同冻土条件下冻土路基的设计及病害防治具有重要意义。
In order to further study the evolution process of subgrade deformation failure in permafrost region, the subgrades at section of K6+200 in the high-temperature and ice-rich permafrost region and at section of K8+200 in the low-temperature and ice-rich permafrost region along Mobei Highway were choose as research objects, the temperature and deformation sensors were installed at different positions and different depths of subgrades, and the evolution processes and characteristics of measured temperatures and deformations under different conditions in high-latitude and alpine permafrost region were analyzed. Analysis result shows that in high-temperature and ice-rich permafrost region, an obvious offset of thaw bulb under subgrade is formed after 2 years service period. Transverse uneven deformation feature of newly-built wide subgrade is observed obviously, there are two thaw bulbs under subgrade, one obviously offsets to the slope toe of subgrade. The permafrost tables at left slope toe and the center of road obviously decrease by 3-4 m, and the settlement of the original natural surface under subgrade is 4-9 cm after 2 years service period. The permafrost table at shoulder remains stable. In low-temperature and ice-rich permafrost region, under ensuring a certain height of subgrade, besides the deformation(post-construction settlement)of subgrade soil in early service time, the subgrade deformation caused by permafrost melt is very small, therefore the subgrade stability in low-temperature permafrost region is relatively superior. So, the conclusion further illustrates the causes of serious deformations of subgrade and pavement in high-temperature permafrost region, and offers the reference for the design and disease control of pavement damage resistance in high-latitude and alpine permafrost region. The result further illustrates the failure characteristics and reasons of uneven deformation, such as settlements, longitudinal crack and so on. It is concluded that under ensuring a certain