Field and numerical studies on geofoam-infilled dual barriers to screen ground vibrations

The unwanted vibrations resulting from man-made activities are very common and can cause damage to the surrounding buildings. Previous studies have suggested single barriers for vibration isolation that require unrealistic depth requirements. To effectively control the vibration-related hazards, a geotechnical seismic isolation strategy of dual shallow barriers has been explored in the present work. Geofoam has been used as a filling material in the barriers. Extensive field studies and numerical simulations have been performed to isolate the continuous harmonic vibrations. The Lazan-type mechanical oscillator has been utilized to generate continuous harmonic vibrations of frequencies ranging from 20 to 45 Hz. A comprehensive numerical investigation has been conducted to screen continuous harmonic vibrations. The barriers were found to eliminate vibrations of higher frequency more effectively compared to low-frequency excitations. The isolation efficiency of EPS15-infilled dual barriers of a normalized depth of 0.31 was noticed to be 45% higher than that of the EPS15-infilled single barrier of a similar depth (where EPS is expanded polystyrene). Furthermore, an optimum depth of 0.5 L_R for EPS15-infilled dual barriers was noticed to be sufficient to reach the vibration-limiting criteria of isolation efficiency equal to or greater than 75% (where L_R is Rayleigh wavelength).