Abstract
An effective reinforcement method for the side wall of a cut and cover tunnel has not been established yet. It is difficult to apply the reinforcement method that has already been developed because the outside of underground structure is surrounded by ground. We, therefore, develop a new seismic countermeasure of the under ground structure based on new concept. In this method a polymer material whose stiffness is quite flexible, is embedded both sides of the tunnel. In this paper, we examined the effect of the covered soil, and analyzed the causes of the effect on seismic isolation. It was found that the covered soil is hardly influenced by the effect of the isolation wall, and it was clarified that the effect of the rigidity ratio between the ground and the structure was high.
