人工冻结黏土冻胀特性试验研究

Experimental Research on Frost Heave of Artificial Frozen Clay

为进一步研究人工冻结黏土的冻胀特性,分别在单、双向冻结和顶部预留一定空间量的单向冻结条件下,对重塑黏土进行了冻结试验。结果表明:冷端温度相同时,单、双向冻结试样冻胀力随时间变化规律一致,但双向冻结试样的冻胀开始时间略早于单向冻结,且在冻胀快速增长阶段,冻胀力增长速率明显快于单向冻结;随着冷端温度的降低,单、双向冻结试样冻胀力都呈非线性增大,但在任一温度水平下,两种模式下的差值基本相同;双向冻结模式下,土样测点的温度及冻结锋面的发展随时间变化规律基本都延纵向对称,其中冻结锋面平均发展速度约是单向冻结条件下的3倍;预留一定空间量的单向冻结试验是可行的,能直接得出土样冻胀力与冻胀量之间的关系。

To further study the frost heave characteristics of artificial frozen clay, freezing experiments of remolded clay were carried out under unidirectional and bidreetional freezing modes and unidirectional freezing with headspace. The resuhs show that, at same temperature, the variations of frost heave force with time are identical under unidirectional and bidrectional freezing modes, but compared to the unidirectional condition, the start time of frost heave under bidrectional freezing mode is slightly earlier, and the increment speed of frost heave force is faster during the rapid growth stage of frost heave. The frost heave force of the two modes both increases nonlinearly with the decrease of temperature, but the deviations are basically the same at the same temperature. The variations of temperature and freezing front with time at measuring points of a soil sample show longitudinal symmetry under bidrectional freezing mode, and the development rate of freezing front is three - time faster than that under unidirectional mode. It is feasible for the freezing test with headspace under unidirectional mode, in which the relationship between frost heave force and amount of frost heave could be obtained directly.