Measured Effects of Vibratory Sheetpile Driving

The installation of sheetpiles using a vibratory hammer is becoming more common. However, this process induces vibrations into the ground which can be transmitted to nearby structures and which may produce settlements in sandy soil layers. A series of field case histories from San Francisco are reviewed where the effects of vibratory sheetpile driving were measured. Typically the soils at the sites consisted of a 10-m (33-ft) layer of loose to medium sand-rubble fill underlain by either dense natural sands or soft San Francisco Bay mud. Horizontal and vertical accelerations and velocities are reported, as well as ground settlements. Accelerations and velocities are found to diminish rapidly with distance from the pile, with greater damping effects observed for cases where softer soils underlie the fills. Where the sheetpiles encountered hard rubble objects, accelerations are double those of the normal case. Settlements are found to correlate with the density of sands in the fills and the level of acceleration.