A semi-analytical approach to anchorage system with defects considering radial leakage of guided wave

Abstract

An equivalent model of a piecewise viscoelastic rod is proposed to investigate the propagation and attenuation characteristics of guided waves in an anchorage/pile foundation system. Based on the property that the leaking wave attenuates rapidly in a viscoelastic medium, the effective radius is introduced to characterize the influence area of the guided wave leaking from the rod to the surrounding rock/soil. The mixing rule of composite materials is used to obtain equivalent material parameters of the rod and the surrounding rock/soil. The semi-analytical solution for the dynamic response of each anchorage segment under arbitrary excitation is derived in the time domain by using Laplace transform and inversion. Then, a system of integral equations is derived from the continuity condition at the interface between segments and it is solved numerically. The comparison of the computational results in validation examples with the related experimental data and the analytical solutions available in references as well as the FEM demonstrates the applicability of the proposed one-dimensional simplified model and the semi-analytical approach. Moreover, the influences of excitation frequency, anchorage geometry, surrounding rock material, and bonding area on the characteristics of guided wave propagation are examined. In addition, the dispersion curves with different parameters and for multiple reflections are given. Finally, the anchorage length and position are identified by the time difference and wave velocity of the interface reflected wave.