Vertical Vibration of Pile in Vibration-Induced Excess Pore Pressure Field

Abstract

Vertical vibration of pile generates the cyclic shear in soil and can induce excess porewater pressure if the soil is submerged and cohesionless. The induced porewater pressure softens the soil and reduces the maximum skin friction allowed at the soil-pile interface. The behavior of a pile foundation under such an environment is numerically studied herein. A soil-pile interaction model and its formulations are first developed in the frequency domain adopting Winkler's hypothesis. They are computationally efficient yet capable of taking into account the effects of porewater pressure rationally. Parametric studies show that the most significant effects associated with porewater pressure are the reduction of the maximum skin friction allowed at the interface and the drastic alteration of the pile response due to slippage. It is found that the skin friction can be fully mobilized far more easily with porewater pressure than without it. This suggests a great advantage in utilizing vibration for driving a pile in submerged cohesionless soil.