ABSTRACT
In evaluating mining conditions in Arctic regions, it is commonly assumed that permafrost contains water only in the solid phase and that it is impermeable and, therefore, effective in preventing movement of ground water. These assumptions, however, are not always valid. As the temperature of the frozen ground in the ore zone is increased, all mining conditions begin to change. Of critical importance is the filtration capacity of underlying, fissured bedrock, which is impermeable when frozen. This important property disappears on thawing and the mine may begin to fill with water, which easily enters through the thawed surface deposits and the fractured bedrock. Furthermore, infiltration of water through fine grained soil and bedrock increases the ground temperature, leading in turn to an increase in permeability. A mathematical model describing the simultaneous transport of heat and water in frozen porous materials has been developed. The physical basis for the model is the analogy between the mechanism of water transport in unsaturated porous media and in partially frozen, porous media. Thermal effects that result from transport of heat by infiltrating water in permafrost ground are accounted for in the model.
