Foundations In Frozen Soils

Abstract

Foundation design in areas of seasonal frost depends on the choice of an appropriate foundation depth and protection of the foundation from the effects of frost, particularly where there is frost-susceptible soil. Under certain conditions, harmful frost action effects may arise. For this to occur, frost must penetrate down to frost-susceptible soil, and sufficient water must be available to sustain the formation and growth of ice lenses. The lenses usually form parallel to the frost front, producing forces or soil movements directed at a right angle to the frost front. These forces can be very large and can lead to heaving or displacement of all parts of the foundation as the soil freezes. The magnitude of heave forces is generally difficult to determine. As it is impractical to restrain heave fully, one should attempt to eliminate it by proper design. In practice, this means that any frost-susceptible soil that will affect the foundation must be either prevented from freezing by proper insulation, or the water supply to the freezing front should be reduced by drainage. Otherwise, such a soil must be excavated and replaced with a frost-stable material.