水汽补给下砂土冻胀量与微观结构参数关联研究

水汽补给可诱发砂土填料的冻胀。基于自主研发的水汽迁移和冻胀试验仪，研究了气态水补给下砂土含水率、温度和冻胀量变化规律；利用体视显微镜对冻结过程中砂土微观结构变化特征进行了研究，结合灰色关联理论分析了宏观指标冻胀量与微观参数之间的关联关系。结果表明：在水汽补给下砂土会发生明显冻胀，冻结 7 d 时冻胀量达到 3.45 mm。砂土经历冻胀后，大孔隙面积占比增加、中小微孔隙面积占比降低，孔隙数量占比变化趋势与面积占比相反，孔隙丰度值变化不大，孔隙定向角在各区间分布趋于更加均匀，孔隙定向概率熵整体呈震荡上升趋势，孔隙分形维数呈下降趋势。此外，利用灰色关联理论，建立了宏观参数冻胀量与平均孔径等微观参数之间的关联关系式，进一步揭示了水汽补给下砂土冻胀的微观机制。

Correlation between frost heave and microscopic parameters of sand under water vapor recharge

Watervapor supply can induce frost heave of sand filler. Based on the self-developedmoisture migration and frost heaving tester, the variations of sand moisturecontent, temperature and frost heave with freezing time under gaseous waterrecharge were studied. The change characteristics of sand microstructure duringfreezing were examined by stereomicroscope. By combining with the greycorrelation theory, the correlation between the macroscopic index, i.e., frostheave and the microscopic parameters was analyzed. Notable frost heaving wasobserved under water vapor supply, and the frost heave reached 3.45 mm after 7days of freezing. After sandy soil frost heaving, the proportion of large porearea increased and the proportions of small and medium micropore area decreased,and the change trend of pore number proportion was opposite to that of areaproportion, while pore abundance value changed little, pore orientation angle distributionin each interval tended to be more uniform, the probability entropy of poreorientation present an overall upward trend of oscillation, and the porefractal dimension showed a trend of decrease. In addition, the grey correlationtheory is used to establish the correlation between the frost heave and theaverage pore size and other microscopic parameters, which provides an insightinto the microscopic mechanism of sand frost heaving under water vapor supply.