Kinematic response of floating piles in two-layered soils subjected to vertically incident S-waves

Abstract

A rigorous solution is proposed for the kinematic transverse response of a single floating pile in the two-layered soil by vertically propagating S-waves. The soil displacements of the two layers are solved by Helmholtz decomposition and the method of separation of variables. The soil mode functions with a series of eigenvalues are calculated and satisfy the weighted orthogonality. The unknown coefficients in the solution functions are obtained in light of the boundary conditions. An infinite series of algebraic equations with unknown coefficients can be solved by truncating the series number. The cutoff frequency, soil reaction factor, and pile curvature along the shaft are investigated for different properties of the adjacent soil. For the pile in the soil with soft upper and stiff lower layers, the dimensionless cutoff frequency is smaller than that of homogeneous soil, but it follows opposite rules when the upper layer is rigid.