The mechanical properties of unsaturated soils

Underground water occurs in two different zones. The first zone, which occurs immediately below the land surface in most areas and above the water table, contains solid grains, water and air and is referred to as the unsaturated soil zone. The other zone is below the ground water table which contains solid grains and water only. In most areas, the unsaturated zone is composed of horizontal or nearly horizontal layers. On the other hand, the movement of water is predominantly in a vertical direction. The mechanical behavior of unsaturated soils can be very different to that of saturated soils. Research studies focusing on the mechanical behavior of saturated soils are by far more numerous as compared to the researches on unsaturated soils. It is obvious that the mechanical behavior of an unsaturated soil is more complex than that of saturated soil. In this study, USTX 2000 (Unsaturated Soil Triaxial Test System) machine which is available in the Geotechnical laboratory of Sakarya University (SAU) is used. This machine can be used to analyze both the static and dynamic properties of saturated and unsaturated soils. Despite its complexity, this machine has been used successfully in SAU. In conclusion, the mechanical behavior of unsaturated soils is analyzed by using this machine and the results obtained are evaluated.