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.