Abstract
The seismically isolated tunnel, which is one of the countermeasures for linear underground structures against earthquakes, is characterized by reducing the transmission of ground strain to the tunnel by smoothing the tunnel strain in the section where the isolation structure is applied. Therefore, it requires a sufficient length of seismic isolation section. Thus, in this paper, as an attempt to shorten the length, the seismic isolation with both functions of Slip and Separation (SaS) is proposed. It is a new seismically isolated tunnel with flexible joints with a function of small amount of displacement absorption at both ends of slip-type seismic isolation. By analyzing earthquake tunnel axial response of the shield-driven tunnel in surface soil deposits with SaS isolation structure and comparing it with the case of conventional slip-type seismic isolated shield-driven tunnel. Then, this paper demonstrates that SaS seismic isolation structure shows a remarkable effect of reducing the tunnel axis distortion which is superior to the conventional seismic isolated structure.
