The Residual Stress in Thawing Soils

Abstract

If a fine grained soil is thawed under undrained conditions, in general an effective stress exists in the soil skeleton. This effective stress is termed the residual stress. In ice-rich soil the residual stress may be zero, but various combinations of stress and thermal histories can result in significant residual stresses being generated upon thawing.A simple procedure for measuring the residual stress is described and the method is employed to obtain values for the residual stress in natural and reconstituted samples of frozen soil. The residual stress is found to be dependent on the void ratio in the thawed undrained condition. A profile of the residual stress with depth is given for the natural permafrost samples that have been tested.Some implications of the residual stress in practice are discussed, with particular emphasis on the undrained strength and deformation properties of thawed permafrost.