In recent decades geotechnical concerns, such as frost damage to highways, disruptions of building foundations and especially problems of gas and oil pipelines, have led to increased knowledge of the thermal and thermodynamic properties of freezing ground. The presence of unfrozen water in frozen ground, its mobility and importance for long term heave and for strength and deformation considerations are basic to practical engineering solutions for complex problems. Generally however, the soils are considered as being saturated.

Interest in the seasonally frozen layer from an agricultural point of view, of necessity must consider partly-saturated soils. The study of the soil water energy relations is fundamental to understanding the particular characteristics of freezing soils. The chemistry of freezing soils, too,has received more attention from the agricultural point of view.

Recently soil contamination in cold regions has presented new research problems arising from the special behaviour of freezing soils. This is a topic drawing together the sometimes disparate approaches. The surface layers of the ground are most affected and may be unsaturated. With time contaminants spread into the soil and may enter the ground water system. While the thermal characteristics, the thermodynamic and hydraulic properties and microstructures of freezing soils in general can now be defined, this is not so for contaminated soils. Leaked oil for example, is an extensive problem in the cold regions. In general very little is known about the modifications of the freezing/thawing process that occur in the presence of oil. Yet it is the modified properties of the freezing soil that largely determine the fate of the contaminant and indeed, the design of appropriate and cost-effective remedial measures.

Peter J. Williams
Distinguished Research Professor
Geotechnical Science Laboratories
Carleton University
Ottawa, Ontario, Canada K1S 5B6
Phone: (613) 520-9004
Fax: (613) 520-9005
E-mail: pwilliam@ccs.carleton.ca