A direct simple shear device for the dynamic characterization of partially saturated soils.

摘要

The importance of unsaturated soil mechanics has become of interest in recent decades to the geotechnical community. Previous investigations have led to the conclusion that inter-particle interactions present in unsaturated soils can contribute additional strength to the soil structure. Recent renovations made to a custom built Direct Simple Shear Apparatus at the University of New Hampshire has allowed researchers to study the dynamic properties of partially saturated soils. The renovations included a new control system, hydraulic components, and data acquisition system to allow the system to become functional from its previous working state. Modifications made to the soil chamber and the installation of a flow pump allows users to use the axis translation technique to control the degree of saturation in the soil specimens. An investigation conducted on a clean sand subjected to medium shear strains were tested at different degrees of saturation from a completely dry to a saturated state. The investigation confirmed the importance of matric suction on both the seismic compression and dynamic properties, as well as the validation of the system to record these properties. Results indicated that higher shear modulus values and lower damping ratios were observed for specimens subjected to larger matric suction values. Further investigations will be needed to address some of the challenges encountered in the system.