Influence of Degree of Saturation on the Dynamic Soil Properties of a Fine-Grained Soil

The degree of saturation of the soil could affect its shear and compressive strength under static conditions. Under dynamic loading, it is possible to observe changes in behavior as a function of effective stress changes due to water content variations. Normally, the fully-saturated condition is considered as the critical shear strength for the design geotechnical structures; nevertheless, this does not necessarily hold true when the dynamic shear strength of unsaturated soil is considered, because the water content affects the transmission of seismic waves through the porous medium and into a structure. Thus, if the same wave amplitude occurs, the dynamic load that reaches a structure could vary. It is important to better understand this behavior so an adequate assessment of the structure during an earthquake is achieved. A series of cyclic triaxial tests with controlled matric suction was conducted to determine Young's Modulus, Shear Modulus, and Hysteretic Damping for the different degrees of saturation tested.