Theoretical and Numerical Study on the Pile Barrier in Attenuating Seismic Surface Waves

Abstract

The purpose of this study is to investigate the attenuation effect of the pile barrier in blocking seismic surface waves by using theoretical and numerical methods. First, we derive the dispersion characteristics of pile barriers embedded in soil from the perspective of periodicity theory to explain that such periodic barriers can attenuate seismic surface waves when the main frequencies fall into the band gaps of the pile barrier. Second, the dispersion characteristics of periodic barriers composed of different inclusions are discussed, and it is suggested preliminarily that scatters with low stiffness and low density are more conductive to mitigate low-frequency surface waves. Third, a three-dimensional transmission calculation model is also developed to illustrate that the attenuation zone of a finite number of piles is consistent with the surface wave band gap. Finally, transient analysis of the periodic pile barriers is performed to validate the block effects on seismic surface waves. The numerical results show that the frequency band gaps of multi-row pile barriers are in accordance with the frequency band gaps of the surface wave in theory, which can greatly mitigate surface ground vibration. The pile spacing, number of piles, and pile length are the key parameters that can affect the width of attenuation zones of the periodic barriers by an appropriate design.