Approach for defective floating pile embedded in layered saturated soils and application in pile integrity test

In this study, a novel analytical method combining a 3D continuum model, Biot propagation theory, a fictitious saturated soil pile (FSSP) model, and a heterogeneous pile model is proposed to analyze the dynamic response of a defective floating pile embedded in saturated soils. The vertical velocity of the defective pile in the frequency domain is obtained by introducing the complete coupling conditions of the pile and soil. With the most widely used half-sine pulse as the excitation force in the low-strain integrity testing of the pile, the solution is extended to the time domain using the inverse Fourier transform (IFT). The rationality and accuracy of the proposed approach are verified via comparison with previous methods and measured data from an engineering example. Parametric analyses are also conducted to investigate the quantitative relationship between the pile defect parameters and the dynamic response characteristics of a defective pile. It is indicated that the depth and length of a pile defect can be roughly evaluated using the proposed methodology when clear signals are reflected from pile defect interfaces in practical engineering.