Effect of Near-Fault Pulsed Ground Motions on Seismic Response and Seismic Performance to Tunnel Structures

Table 5

Three-level fortification requirements and its control index thresholds.

Fortification requirement	Fortification target	Performance level	Threshold
I	After the earthquake, the tunnel is not damaged or slightly damaged and can maintain its normal service function	Normal service	=
II	The tunnel may be damaged after the earthquake. After repairing, its normal service function can be restored in a short time	Available after repairing	=
III	After the earthquake, the tunnel may occur major damage but does not collapse and can be opened to traffic at a speed limit after emergency repairing	Life threatened	= 4