Vertical vibration of pile in radially inhomogeneous soil layers

Based on three-dimensional axisymmetric soil model, the vertical dynamic response of pile in radially inhomogeneous soil layers was investigated with the effect of soil inhomogeneity. First, the soil surrounding the pile was subdivided into arbitrary numerous annular zones, Second, the boundary conditions and continuum assumptions of displacement and stress between adjacent soil zones were developed. Third, the dynamic equilibrium equations of each soil zone are solved from outer to inner surrounding the pile. Third, the dynamic equilibrium equation of pile is also solved and the analytical solutions in frequency domain and semi-analytical solutions in time domain are obtained with the coupled condition of pile-soil interface. The theoretical results reflect the influences of radial soil inhomogeneity on dynamic response of the pile and the soil.