Experimental study on vibration reduction by using soilbag cushions under traffic loads

Abstract

The dynamic behaviour of a subgrade with soilbags (filled with different materials) under traffic loads was investigated through a series of laboratory experiments. Three spaced hydraulic jacks with phase-shifted excitations were used to simulate moving loads. Different materials, namely gravel, coarse sand, and fine sand, were filled into the subgrade soilbags underneath the ballast. Equations of the peak acceleration and effective soil pressure with respect to the subgrade depth were derived to obtain an insight into the subgrade-load interactions. In addition, the effects of subgrades with and without the soilbags on the vibration and settlement were investigated and compared. The experimental results show that the peak acceleration decreases linearly with increasing depth from the vibration source, while the attenuation of the effective soil pressure increases with increasing distance from the vibration source. The settlement in reinforced subgrade is much smaller than that in unreinforced subgrade under three-jack excitation.