Underwater shake table tests on waterfront structures protected with tire chips cushion

A series of large-scale underwater shaking table tests was performed on a gravity type model caisson protected by a cushioning technique using tire chips (scrap tire derived recycled product). The function of the tire chips cushion is to reduce the load and restricting the permanent displacement of such waterfront retaining structures during earthquakes by exploiting the compressibility, the ductility and the energy absorbing capacity of tire chips. The seismic performance of such earthquake resistant techniques was evaluated by subjecting the soil-structure system into three different earthquake loadings (two actual earthquake records and one synthetic earthquake), and measuring the respective responses. The results demonstrated that the seismic load against the caisson quay wall could be substantially reduced using the proposed technique. In addition, the presence of the protective tire chips cushion could significantly reduce the earthquake-induced residual displacement of the caisson quay wall.