An estimated 102 millions scrap tires are generated annually in Japan, 90% of which are recycled for thermal, material and retreading purposes. A major share of scrap tire recycling goes to the thermal recycling, a process that generates carbon dioxide, and is, thus contradictory to the principle of the Kyoto protocol that entered into the force since February 2005. However, the share of recycling as materials is still far from satisfactory. This research is an attempt to contribute towards material recycling of scrap tires by utilizing tire chips as a geomaterial for earthquake resistant reinforcement of geotechnical engineering structures. The objective of this research is to exploit the compressibility of tire chips by using such material as a cushion behind the massive port structures to reduce the load against the structures during the earthquake. Function of the sandwiched cushion layer is to provide flexibility, and thereby stability to a structure during the earthquakes by absorbing the energy. Thus, it is expected that only a part of the load coming to the structure will be transferred.
　A series of shaking table tests of was performed on a model caisson by using a large underwater shaking table assembly. The seismic performance of the developed technique was verified by subjecting the soil-structure system into three different earthquake loadings and measuring the respective responses. The results demonstrate that the dynamic load against the caisson quay wall could be significantly reduced using the proposed earthquake resistant technique. Also, the presence of tire chips cushion could significantly reduce the earthquake-induced residual displacement of the caisson quay wall. In addition, owing to highly permeable nature of the tire chips cushion material, the pore water pressure building up in the immediate vicinity of the structure could be checked, and thus preventing the occurrence of liquefaction. Application of the developed technique, thus, not only contributes towards a better environment, but also provides a cost-effective design alternative for earthquake resistant design of port and harbor facilities.