1999 Volume 9 Pages 39-46
The seismic isolation for underground structures is the system in which a tunnel body is covered by a thin isolation layer consisting of elastic rubber with low shear modulus. It was applied for the first time to a shield-driven tunnel used as a common duct at a junction with a vertical shaft. In order to verify shearing capability of the newly formed isolation structure, an in-situ test was conducted right after its construction. The shear resistence of the isolation layer due to lateral movement of a tunnel body including a shield machine was measured when the tunnel body was pushed toward the cutting face by oil jacks fixed at the shaft wall. As a result, the relationship between reaction force and deformation for the isolation layer revealed that the isolation layer with necessary shear modulus and shearing capability was successfully formed.
