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为掌握冻土冻结变形规律,揭示冻结变形机理,采用自行研制的温控体变仪精确测量不同饱和度、孔隙比土样的冻结变形,为计算冻土的体积含冰量,对非饱和粉质黏土冻结温度进行了测量。室内试验结果及其数据分析表明:(1)非饱和粉质黏土冻结温度(冰点)主要由土样初始基质吸力决定,基质吸力越大,冻结温度越低。(2)非饱和粉质黏土冻结变形随饱和度变化存在两种截然不同的机制,饱和度较低时,冰水相变影响较小,土体呈冻缩特征;饱和度较高时,冰水相变占主导作用,导致土体结构破坏,呈冻胀特征。(3)非饱和粉质黏土冻结体应变与土体体积含冰量和初始孔隙比具有良好的经验关系,可以基于体积含冰量和初始孔隙比预测土体冻结体应变,其中体积含冰量由土体冻结温度、温度、饱和度、干密度计算得到。
In order to grasp the law of freezing deformation of frozen soil and to reveal the mechanism of freezing deformation, the frozen deformation of soil sample with different saturation and void ratio is accurately measured by a temperature-controlled strain gauge developed by ourselves. In order to calculate the volume of frozen soil, Quality Clay freezing temperature was measured. Laboratory test results and data analysis show that: (1) The freezing temperature (freezing point) of unsaturated silty clay is mainly determined by the initial suction of soil samples. The larger the substrate suction, the lower the freezing temperature. (2) There are two distinct mechanisms for the variation of freezing deformation of unsaturated silty clay with saturation. When the saturation is low, the ice-water phase change is less affected and the soil is frozen and contracted. When the saturation is high, Water phase change dominates, resulting in the destruction of soil structure, was characterized by frost heave. (3) There is a good empirical relation between the strain of unsaturated silty clay frozen body and the ice volume and initial void ratio of soil volume, and the frozen body strain of soil can be predicted based on the volumetric ice content and the initial void ratio. The ice volume Calculated from the soil freezing temperature, temperature, saturation, dry density.