Experimental Investigation of Thermal and Hydraulic Properties of Ice-Rich Saline Permafrost in Northern Alaska

Unfrozen water content and thermal properties are factors in understanding permafrost degradation processes, yet there is a general lack of information on the hydro-thermal properties of relatively undisturbed ice-rich permafrost in Arctic coastal regions. In this research, we measured the unfrozen water content as a function of temperature in samples from near-surface undisturbed ice-rich permafrost using a pulsed nuclear magnetic resonance (P-NMR) testing system, in a temperature-controlled environment. We measured frozen and unfrozen thermal conductivity and heat capacity of the permafrost samples. The average frozen and unfrozen thermal conductivities are 2.23 and 1.30 W/m · K, respectively, and the average frozen and unfrozen heat capacities are 1.91 and 3.00 MJ/m3/K, respectively. To investigate the effect of salinity on unfrozen water content of permafrost, we measured the samples’ salinity levels. The salinity levels of the permafrost samples varied, ranging from 0.5 to 15.2 parts per thousand. Based on these data, we established an empirical relationship between salinity and unfrozen water content for ice-rich organic silty permafrost that can be used for engineering purposes.