季节性冻土区铁路路基冻融变形规律

为探究冻融循环作用对季节性冻土区铁路路基变形特性的影响,以兰新铁路的路基填土为研究对象进行冻融循环试验和固结压缩试验,得到了冻融变形和压缩特性的变化规律,并利用正交试验对压缩特性的影响因素进行显著性分析。试验结果表明:随着冻融循环次数的增加,冻胀率和融沉系数均呈多项式函数增加;在相同冻融循环次数下,两者均与含水率呈正相关,与压实度呈负相关。压缩模量随冻融循环次数的增加先增加,最终趋于稳定,各因素及其交互作用对压缩模量的影响从高到低依次为压实度B、含水率C、冻融循环次数A、B和C的交互作用BC、A和B的交互作用AB、A和C的交互作用AC。建议选取9次冻融循环后的压缩模量作为兰新铁路路基强度设计值,该研究成果对防治冻胀融沉和控制路基变形具有一定的指导意义。

Law of Deformation of Railway Subgrade Caused by Cyclic Freezingand Thawing in Seasonal Frozen Soil Region

In order to explore the influence of cyclic freezing and thawing on the deformation characteristics of railway subgrade in seasonal frozen soil region, we performed freeze-thaw cycle test and consolidation compression test on the roadbed filling of Lanzhou-Xinjiang Railway as the research object. Through the tests we obtained the regularities of railway subgrade deformation caused by freeze-thaw cycles and compression characteristics. Moreover, we analyzed the influencing factors of compression characteristics by significance test via orthogonal analysis. Results revealed that the frost heave rate and the melting subsidence coefficient both increased in a power function with the increase of the number of freeze-thaw cycles, and both were positively correlated with water content and negatively correlated with compaction degree at the same freeze-thaw cycle. The compressive modulus of subgrade soil increased at first and then stabilized with the proceedings of cyclic freezing and thawing. The compaction degree (B) had the largest influence on compressive modulus, followed by water content (C), freeze-thaw cycle (A), the interaction between B and C, the interaction between A and B, and the interaction between A and C in sequence. We recommend choosing the compression modulus after nine freeze-thaw cycles as the design value of the road strength of Lanzhou-Xinjiang Railway. The research finding is of guiding significance for the prevention and control of frost heaving and subsidence of railway subgrade.