STATE-OF-THE-ART OF INFLUENCE OF FREEZE-THAW ON ENGINEERING PROPERTIES OF SOILS

It has become a common understanding that frost action is a kind of weathering process, which considerably changes engineering properties of soils due to cryogenical actions. Soils newly exposed to freeze-thaw in cold regions tend to change their properties. Therefore, care must be taken with respect to the freeze-thaw induced influence on stability and deformation of engineering constructions. With a view of the state-of-the-art, this paper reviews the general findings of the research on this topic on the basis of an extensive literature study. Technically, the following aspects of soil behavior regarding freeze-thaw are included: the means of investigation and testing techniques, physical and mechanical properties as well as mechanism analysis. Typical research results are taken from various resources and listed herein. The influences of freeze-thaw on soil properties can be summarized that, permeability of soils is generally increased despite of the change of density; densities of loose and dense soils are changed in the opposite way; structure of undisturbed soils can be changed, as the results peak in the stress-strain curve is not as pronounced as that in the pre-freezing ones; strength change is not well in agreement from the previous studies. The authors' comments on previous studies and ideas for further investigation with regard to particularly concerned aspects are given. It is suggested that the original state, such as stress state, density and preconsolidation ratios should be taken into consideration for a more systematic investigation. Meanwhile, the deformation versus time during freezing and thawing may serve as a sound proof of change in particle bondings.