Abstract: Regarding the soil profile in seismic liquefied deposits as being composed of a non-liquefied crust layer at the ground surface, a liquefied layer in the middle of the deposit and a non-liquefied base layer, and based on the theory of saturated porous media and Novak’s thin layer method, the dynamic behavior of an end-bearing pile in liquefied viscoelastic under axial force soil layer is investigated. The horizontal dynamic impedance of liquefied soil was obtained using Helmholtz decomposition. The analytical expressions of the harmonic vibration and dynamic complex stiffnesses of the end-bearing pile in liquefied soil under axial force are obtained with the transfer-matrix method. A parametric study was conducted to analyze the influences of the axial force, the slenderness ratio of the pile, pile-soil modulus ratio and the coupled coefficient of fluid and solid phase on the dynamic stiffnesses and dampings. It is shown that, with different slenderness ratio of the pile, pile-soil modulus ratio, coupled coefficient, the absolute values of the dynamic stiffness of pile with axial force are smaller than those of pile without axial force; and the change tendency with frequency are the same. The influence of the axial force on the dynamic impedance of the horizontal vibration pile is remarkable. The absolute values of the dynamic stiffness factors of the horizontal vibration of pile are approaching to zero; and the pile will buckle with the axial force increasing. Furthermore, the influences of the slenderness ratio of the pile and the pile-soil modulus ratio on the dynamic impedances of pile are notable; and the influence of coupled coefficient of fluid and solid phase is trivial.

Key words: liquefied soils, axial force, end-bearing pile, horizontal vibration, dynamic stiffness