Effects of inner soil on the vertical dynamic response of a pipe pile embedded in inhomogeneous soil

This paper is concerned with the effects of inner soil on the vertical dynamic response of a pipe pile embedded in a vertically multilayered and radially inhomogeneous soil. The soil is considered a three-dimensional axisymmetric medium, the radial inhomogeneity of which (due to the construction disturbance effect) is simulated by gradually varying the soil parameters in the radial direction. The pipe pile is treated as a vertical, hollow, viscoelastic, one-dimensional bar. The velocity admittance and reflected signal at the pile head are derived by solving the equilibrium equations for the pile and soil. They are then used to obtain an insight into the coupled effects of the inner soil and several related factors, such as the pile parameters, construction disturbance effect and pile defect characteristics, on the vertical dynamic response of the pipe pile concerned in pile integrity testing. A comparison with the measured data is also presented to verify the reliability of the proposed solution.