A semi-analytical solution for vertical dynamic response of noncircular piles in layered viscoelastic soils

The vertical dynamic response of noncircular piles in viscoelastic soil is investigated by developing an interaction model between the noncircular piles and the viscoelastic soil in this paper. The differential equations of the soil and pile displacement functions are derived through variational calculus and Hamilton's principle, assuming the noncircular pile displacement function and the soil displacement field The pile-soil interaction problem under vertical dynamic loading is formulated as a coupled solution involving both an ordinary differential equation (ODE) and a partial differential equation (PDE). A novel computation method for the coupled ODE and PDE are presented, resulting in the numerical solution for the dynamic response of noncircular piles. The reliability of this method is validated through comparisons with analytical solutions from existing studies. Furthermore, parametric analyses are conducted separately in the high-frequency and low-frequency ranges to investigate the effects of pile cross-section shape, pile-soil relative modulus, slenderness ratio, soil modulus distribution, and layered soil thickness on the vertical dynamic response of noncircular piles. It is indicated that the impact of the aforementioned parameters on the vertical dynamic response of noncircular piles is frequency-dependent.