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Abstract How to determine the unfrozen water content in frozen soil is still a key and difficult problem in geocryology. For measuring the unfrozen water content in frozen silt in laboratory，silt samples are taken into isothermal air to melt by natural convection after being frozen at a negative temperature with the temperature-time history recorded. Based on Newton?s law of convection exchange，a analytical model reflecting the variation of the temperature with time throughout whole process is formulated. Some important parameters such as the convective heat transfer coefficient，freezing point and length of melting time are then obtained by fitting the temperature-time history of the tests. On the relationship between ice mass and quantity of heat absorbed in process of thawing，a thermal model of the unfrozen water content in practically frozen state is presented. The results indicate that the unfrozen water content in silt in practically frozen state is about 3.75% when temperature is －4 ℃. Based on the unfrozen water content obtained by this method，the process of the sample melting is then back analyzed. It shows that the analytical results match well with the measured temperature，and feasibility of the proposed analytical model and test method is proved.
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Received: 27 April 2012
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2012, Vol. 31 
