Torsional dynamic response of tapered pile considering compaction effect and stress diffusion effect

Considering both the compaction effect of pile surrounding soil and the stress diffusion effect of pile end soil, this paper theoretically investigates the torsional vibration characteristics of tapered pile. Utilizing the complex stiffness transfer model to simulate compaction effect and tapered fictitious soil pile model to simulate stress diffusion, the analytical solution for the torsional impedance at tapered pile top is obtained by virtue of Laplace transform technique and impedance transfer method. Based on the present solution, a parametric study is conducted to investigate the rationality of the present solution and the influence of soil and pile properties on the torsional vibration characteristics of tapered pile embedded in layered soil. The results show that, both the compaction effect and stress diffusion effect have significant influence on the torsional vibration characteristics of tapered pile, and these two factors should be considered during the dynamic design of pile foundation.