Soil impedance in vertical vibration of a floating pile

Abstract

An analysis is presented here to give the soil impedance on a vertically vibrating floating pile. The soil is assumed to be a homogeneous elastic halfspace. The analysis uses the slenderness aspect of the pile to assume that the pile action is that due to a line distribution of vertical loads. Also, it is assumed that the wave length of the waves generated in the soil is much larger than the pile diameter. The analysis leads to an expression for the shear force acting along the length of pile. This expression is similar to the one given by Baranov. Whereas the Baranov expression assumes that only horizontally propagating shear waves are generated by the vibrating pile, the present analysis incorporates axisymmetric waves generated by the pile of finite length. When the pile length is made infinite the present result leads to the Baranov expression. Through a numerical consideration it is shown that the latter expression is valid near the soil surface only and that there is considerable departure in the interior of the soil.