A New Close‐Formed Solution for Torsional Vibration of a Defective Pipe Pile in Radially Heterogeneous Soils

ABSTRACT Utilizing the dynamic theory of 3D continuous medium and 1D elastic rod, this paper obtains a new close‐formed solution for the torsional vibration of pipe piles, with regard to both the pipe pile defect and the surrounding soil radial heterogeneity effect. Firstly, combining Laplace transform and complex stiffess transfer method, the tangential stress on the pipe pile from the soils can be obtained. Secondly, the close‐formed solution for the torsional vibration characteristics (TVC) of pipe pile head is derived, via combining the continuity conditions of the soil‐pipe pile system and the transmissibility of impedance functions. Further, using the inverse Fourier transform (IFT) and the convolution theorem, a semi‐analytical solution for the time‐domain reflected signal function of pile head velocity is achieved. Finally, the accuracy of the reduced solutions derived in this paper is validated via a comparison analysis with existing theoretical solutions. Moreover, a parameterized analysis is implemented to discuss the impacts of different types of pile defects and radial heterogeneity effects on the TVC of pipe piles.