Abstract: Using the analytical method, vertical vibration characteristics of pipe pile in saturated viscoelastic soil considering mass-coupling effects are investigated in the frequency domain. Based on Biot’s dynamic theory, the expressions for displacement and stress of the saturated viscoelastic soil are obtained by using Novak’s layer method. The pipe pile is treated as the Euler-Bernoulli rod. By utilizing the continuity conditions between the soil and pipe pile, a general analysis method for the vertical vibration of the pipe pile in the saturated viscoelastic soil is presented; and the expression of the complex dynamic stiffness at the pile top is obtained. On the basis, the comparative analysis between the vertical vibration characteristics of solid pile and one of pipe pile in saturated soil is made. By using the numerical example, the influences of mechanical parameters of soil around the pile and inner soil on the dynamic stiffness factor and equivalent damping at the pile top are investigated. It is shown that the vertical vibration characteristics of solid pile and pipe pile have significant difference.

Key words: saturated viscoelastic soil, pipe pile, vertical vibration, dynamic complex stiffness