Thermally induced water migration in frozen soils: Fid-Bau Portal

Thermally induced water migration in frozen soils

Perfect, E. / Williams, P.J.

Abstract An apparatus has been developed for the direct measurement of thermally induced water migration in saturated frozen soils. The frozen soil sample and reservoirs are sandwiched between two end plates containing Peltier modules. These cooling devices are controlled by a thermoelectric cooling control system, which can maintain temperatures constant to within $± 0.02° C$ under steady state conditions. The water in the reservoirs remains unfrozen because it contains dissolved lactose. When a linear temperature gradient is established across the system, water passes from the ‘warm’ reservoir into the prefrozen sample and out into the second, colder, reservoir. Observed rates of flow are compatible with permeability values for frozen soils measured earlier. The results are discussed with regard to current theoretical and applied studies of frozen ground. Unfrozen water in frozen soils has a potential which is lower than pure bulk water by an amount increasing as the temperature decreases. Thus, a temperature gradient in frozen soil implies a flux of water in the direction of decreasing temperature, at a rate dependent on the permeability in the frozen state.