Significance of Impedance Ratio in Case of Infilled-Pile Barrier for Vibration Isolation

Abstract

This paper focuses on the significance of impedance ratio between soil and the infill material in vibration isolation using pile barrier system with varying the infill materials. The study is accomplished using 3D finite element software Plaxis. The finite element model of the current study consists of a row of piles infilled with various isolation materials, i.e. Fly ash, EPS Geofoam and tyre chips to create a barrier system for the vibration waves. The piles are surrounded by homogeneous clay medium. Each combination of clay and isolation material is analysed with reciprocating machine induced harmonic loads of varying frequencies and the time acceleration responses are obtained. From the acceleration responses, the maximum displacement amplitude with horizontal distance is plotted to observe the variation of diminishing amplitude along the horizontal distance as waves passes through the barrier. The variation of amplitude reduction ratios with frequency are also computed by comparing the amplitude of the homogeneous clay layer alone and combination of clay layer and isolation material. It is evident from the results that the isolation efficiency of the material is better within attenuation zone. It is clear from the overall analysis results that as the impedance ratio increases a wider attenuation zone can be obtained.