Soil Plugging and Relaxation in Pipe Pile during Earthquake Motion

Abstract

The objective of this paper is to investigate the effect of seismic loading of soil on the relaxation of the resistance of soil plugs in open-ended pipe piles driven into saturated sand. An experimental study was performed at small scale by driving an instrumented open-ended model pile into saturated sand in a pressure chamber by impact and vibration, performing static compression loading tests to failure, applying simulated horizontal seismic shaking to the soil, and extracting the piles and loading the plugs. During static compression loading, slippage of the plug relative to the interior surface of the pile did not occur in either the impacted or vibrated piles, although the plug in the vibrated pile developed only about 0.5–0.7 times the resistance of the plug in the impacted pile. Most relaxation in pile resistance during seismic loading occurred in outer shaft friction and not in the plugs. Static loading of the plugs after the seismic event indicated that they remained intact.