Numerical Study on Seismic Isolation Effect of Gravel Cushion

The cushion consisted of gravels can be used as an isolation layer to reduce the seismic response of upper structure. In this study, numerical simulation of the isolation layer was performed using discrete element method. Effects of foundation base pressure and cushion thickness on the isolation effect were investigated. Isolation mechanism of the cushion was studied at mesoscale by exploring the movement and coordination number of the particles. The results show that the gravel cushion can reduce the seismic response of the upper structure. The isolation effect of the cushion is shown to increase with the increase of layer thickness and decrease with the increase of base pressure. The objective of this study is to provide recommendations for future design of composite foundations in earthquake area.