Analytical solution for longitudinal dynamic complex impedance of tapered pile

The longitudinal dynamic complex impedance of tapered piles in layered ground is investigated. Assuming the surrounding soil to be plane strain model and considering variable cross-section of the tapered piles and stratification of the surrounding soil, the pile-soil system is discretized into finite segments. Then, by means of the Laplace technique and the impedance function transfer method, the analytical solution of complex stiffness of the tapered piles under vertical exciting force is derived. Additionally, by means of parametric study method, the influence of the cone angle on the complex stiffness at the pile top is investigated. It is shown that the amplitudes of resonance peak of dynamic stiffness curve and dynamic damping curve increase as the cone angle increases. When the length of tapered piles is variable and other parameters are unaltered, the amplitude of resonance peak of dynamic stiffness curve decreases as the cone angel increases and the amplitude of resonance peak of dynamic curve increases as the cone angel increases. When the radius of tapered pile tip is variable and other parameters are unaltered, the amplitudes of resonance peak of dynamic stiffness curve and dynamic damping curve increase as the radius of tapered pile tip increases.