Variation of Degree of Saturation in Unsaturated Silty Soil

Summary

This paper presents the results of an experimental study on variation of degree of saturation of a compacted unsaturated silty soil during isotropic loading and unloading. A series of laboratory experiments have been conducted in a double-walled triaxial cell (and a conventional triaxial cell for saturated samples) on samples of a compacted silty soil. In the experiments the soil samples were subjected to isotropic consolidation followed by unloading under constant suction. The results show that during consolidation a significant increase in degree of saturation was observed. In contrast, during subsequent isotropic unloading, where only a very small elastic component of swelling occurred, the changes of degree of saturation were very modest. Comparison has been made between the experimental and theoretical prediction using a relationship proposed in the literature.