I am currently exploring the possibility of using vibro hammer for the installation end-bearing steel H-piles due to environmental concern. Does anyone has any experience using vibro hammer for the installation of end-bearing piles? If yes, what are the pile performance (capacity and load-settlement)? What are the measures taken to ensure proper seating? Many thanks in advance.
At present, no well-documented relationaships exist between delivered energy during vibratory sheep (pile) driving and endbearing capacity. However, in certain regions and for specific pile types, empirical relationships do exist.
One important aspect is that vibratory-driving of piles and sheet piles is operator-depending (type of vibrator and its operation, frequency and amplitude etc.). In most cases, bearing capacity is therefore determined using impact hammers and stress-wave measurements.
However, if the bearing capacity depends mainly on shaft resistance, static methods can be used to asses the skin friction and a simplified method can be used to estimate base resistance (for instance from CPT measurements).
I might add to Rainer's comments that if the pile is installed using vibratory methods because of environmental concerns, it may be acceptable to give the pile a small number of impacts with a pile driving hammer in its installed position. Much of the energy will be transmitted to the soil at depth, and the surface effects may be significantly reduced and acceptable. Stress-wave measurements would then be performed to ensure compliance with acceptance criteria. Of course, static load testing is another (expensive but vibration-free option).
I might add that if there are dense layers above the rock then the pile is likely to refuse in these layers and not reach the rock. Vibratory driving is highly sensitive to end bearing. Dynamic pile testing can easily verify capacity as suggested by Julian Seidel. Garland Likins, Pile Dynamics