General report on mechanical properties of frozen soil

The state of the art papers and contributions by many authors to this session contain much valuable information on the time-dependent strength-deformation behavior of frozen soil materials. They illustrate different methods for modelling the highly complex interaction between a solid soil skeleton and the pore matrix composed of ice, unfrozen water, and air. Some of the papers rely largely on empirical curve fitting techniques and available experimental data to show various relationships. These papers recognize that changes may occur continuously with time as a function of temperature, stress state, and/or strain level. They show that these variables effect the stress-strain-time behavior differently for frozen sands as compared to frozen silts or clays. All the papers are, in different ways, directed towards development of more rational design techniques involving frozen soil. They recognize that the physical mechanisms controlling strength of frozen soils have basically three components: ice strength; soil strength; and soil skeleton-ice matrix interaction through dilatancy effects and structural interference. The relative importance of these strength components remains, for a range of soil types, only partly defined in terms of temperature, strain rate, and confining pressure. A brief review using information from various authors appears to be appropriate.