Effect of compaction energy on shear wave velocity of dynamically compacted silty sand soil

This study was focused on the effects of compaction energy on the dynamic properties of a silty sand in its as-compacted state in relation to the measured values of matric suction. The influence of the imparted energy on the shear wave velocity and the small-strain shear modulus of the compacted soil was studied for three different energy levels that correspond to the standard Proctor as well as reduced and enhanced. The specimens were prepared with moisture contents ranging from the dry to wet of optimum, and subsequently compacted to known dry unit weights for which the corresponding matric suction and shear wave velocity were measured. While a non-destructive technique adopting Bender elements was used to determine the shear wave velocity, the matric suction was evaluated using the filter paper method. Test results reveal that the shear wave velocity increases with the level of imparted compaction energy and the associated matric suction developed in the compacted soil. However, the change in shear wave velocity along the compaction curve is very significant. Pronounced compaction energy dependence is observed on the dry side of the optimum moisture content, whereas on the wet side of the optimum the matric suction governs the variation in the shear wave velocity.