Effect of freezing and thawing on K ₀ geostatic stress state for granular materials

The coefficient of lateral stress at rest, K ₀, is an important soil parameter that characterizes the geostatic stress state of soils. In this study, an experimental testing program was established to investigate the values of K ₀ for granular materials that are subject to freezing and thawing. Various material conditions, including different fines contents, relative densities and freezing-thawing cycles, were considered in the testing program. The values of K ₀ for thawed condition were higher than for unfrozen condition with net volume decrease. The effect of freezing and thawing became more pronounced as fines content increased while the effect of relative density was small. From the multi-cycled freezing-thawing tests, it was observed that the increase in K ₀ was most significant during the first freezing-thawing cycle. For frozen condition, the values of K ₀ were very low up to a certain limit stress level. Beyond the limit stress level, the values of K ₀ became higher and close to those of unfrozen condition. The increases in K ₀ with net volume decrease after freezing and thawing process was explained with internal changes in microstructure and stress state of soils.