Experimental study of frost heave mechanism

为了阐明冻胀现象的机理，进行了以下试验。高冻易感土与多孔板冻胀试验。2 .电场作用下不冻水迁移实验。用核磁共振测量未冻水含量和未冻膜厚度。刚性壁面附近流体行为的分子动力学研究。本研究得到了以下结果：1)利用分层多孔板得到了冰偏析速率与冰偏析表面温度的关系。实验结果表明，随着冰分离表面温度的降低，冰分离速率降低。这可以解释为随着温度的降低，未冻水含量降低，水粘度增加。2)对冻胀试验后冻结试样的纵断面进行复制，通过图像分析得到冻胀后冻结试样的含冰量。从实验结果得到了分离冰含量与冻结速度和温度梯度的关系。3)通过电场作用下的冻胀实验，测量了未冻水的运动。结果表明，电渗透流量对冻结过程中水的再分配有一定的调节作用。4)采用核磁共振法测定易冻土的未冻水含量。用总比表面积计算平均未冻膜厚度。将计算结果与范德华力和双电层计算结果进行了比较。5)从壁面流体的分子动力学研究来看，壁面流体表现为固体状，自扩散常数比体态小一个数量级。

To clarify the mechanism of frost heave phenomena, the following experiments are performed.1. Frost heave experiments using high frost susceptible soil and porous plates.2. Experiments on unfrozen water migration under the electrical field.3. Mesurement of unfrozen water content and unfrozen film thickness using neclear magnetic resonance.4. Molecular dynamics study of fluid behavior adjacent to rigid wall.The following results are obtained by this study1) We obtained the relationship between the ice segregation rate and the temperature of ice segregating surface by using layred porous plate. The experimental results showed that the ice segregation rate decresed with decreasing temperature of ice segregating surface. This was explained by the decresing unfrozen water content and increasing water viscosity with decreasing temperature.2) From a replica of vertical section of frozen sample after the frost heave experiment, the ice content was obtained with image analysis. From the experimental results, the relationship was obtained between the segregated ice content and freezing speed and temperature gradient.3) From the frost heave experiments under the electrical field, the movement of unfrozen water was measured. The result showed that the amount of electro-osmotic flow was conperable to the water redistribution during freezing.4) The unfrozen water content of frost susceptible soil was measured with neuclear magnetic resonance. The average unfrozen film thickness was calculated with total specific surface area. The results are compared with the calculated results using Van der Waals force and electric double layr.5) From the molecular dynamics study of fluid adjacent to the wall, the fluid near the wall behaved as soilid like and the self-diffusion constant became one order smaller than the bulk state.