Dynamic vertical response of piles in nonlinear soil

An analytical solution to the plane-strain axisymmetric problem of a vertically vibrating pile slice is presented, and the dynamic vertical response of piles in nonlinear soil is examined in this study. The impedance of soil layers are formulated based on a model of a boundary zone with nonreflective interface, involved with both cases of weakened and strengthened zones around the pile. With the impedance of the soil medium derived, the stiffness and damping of a pile are presented using the finite-element method. The validity of the approximate approach proposed in this paper is verified with dynamic experiments on a full-scale pile in the field, and the theoretical predictions match the nonlinear response of the pile subjected to different excitation intensities.