How does vibratory driving compare to drop hammer driving with a composite pile?
With a drop hammer you know the initial resistance or capacity of the driven pile. We do not have test data comparing vibrated piles to hammer driven piles in the same ground conditions. There is no easy method for determining the load bearing capacity of piles during installation with a vibratory hammer that I know of, and without a blow count you would need a static load test. They could be vibrated in and a drop hammer used to drive the last couple of feet to determine capacity. In talking to a couple of pile drivers, they felt that if the vibrated piles reached refusal with less than a 2’ penetration variation between them the values would be in the same range in inch-pounds as the hammer energy. This may work if you have soil data and know the energy of the hammer.
