Abstract: The static and dynamic characteristics of cast-in-place concrete large-diameter pipe pile (PCC pile for short) are not the same as a common solid pile because of the difference of inside and outside frictions. Based on an analytical solution deduced by the authors, the dynamic responses of PCC pile, solid pile with the same cross-section area and solid pile with the same outer diameter are analyzed. The results indicate that the displacement amplitudes among different pile models have little difference when the tip resistance is relatively small, however, they have greater difference when the tip resistance is relatively large. The displacement amplitude of solid pile is larger than that of PCC pile with the same section area, while the displacement amplitude of solid pile with the same outer diameter is smaller. The phase-frequency curve of the displacement presents periodical oscillation; the peak value of solid pile is larger than that of PCC pile; and the frequency corresponding to the peak of solid pile is higher than that of PCC pile. The oscillation aptitudes of dynamic stiffness among three pile models are different. The real part of the dynamic stiffness of solid pile with the same outer diameter is the largest; that with the same section area takes the second place; and that of PCC pile is the smallest. The imaginary part of the dynamic stiffness of solid pile with the same outer diameter is the largest; that of PCC pile takes the second place; and that with the same section area is the smallest. The velocity admittance has similar characteristics. The velocity admittance with the same outer diameter is the largest; and that with the same section area is the smallest. The capacity of unit volume concrete is fully exerted for PCC pile; thus the dynamic response of PCC pile is smaller than solid pile with the same cross-section, and the concrete is more economic than the solid pile with the same outer diameter.

Key words: large-diameter pipe pile, dynamic response, displacement amplitude, dynamic stiffness, velocity admittance