Modelling unfrozen water content in a silty clay permafrost deposit

The mechanical properties of both unfrozen soils and permafrost soils are influenced by the amount of unfrozen water in the pore space. When dealing with foundation engineering in permafrost areas it is essential to estimate the unfrozen water content (wu). This paper deals with the establishing of a calibration equation for determining the unfrozen water content of a Greenlandic silty clay permafrost deposit. Calibration experiments have been conducted for water contents in the interval 0 – 10 % at both 5 °C and 22 °C. Calibration equations are verified against permittivity data from a permafrost core of material properties similar to the test soil. The calibration for 5°C is seen to make a good fit to the permafrost core data. Further experiments should be performed in order to extend the range of water contents tested and hence the range of validity of the calibration equation.