The seismic isolation structure for urban tunnels, in which an isolation layer is formed between a tunnel lining and surrounding soil, enables us to reduce considerably the sectional forces of a lining in the tunnel axial direction. Such an isolation layer must have a low elastic modulus and a high Poisson's ratio of almost 0.5.
This paper presents a new silicone-based material for a seisimic isolation layer. Laboratory tests were carried out to obtain material properties, and a material injection test was conducted using a large-scale soil chamber and a tunnel model. Then, the appropriatenes of the new developed material as the isolation material was verified.