The tunnel industry considered that tunnels were naturally resistant to earthquake action for many years, as they did not experience the same high levels of shaking as surface structures. This perception was supported by the relative good historic performance of tunnels and underground structures, especially of tunnels in rock, during large earthquakes. Dowding and Rozen (1978) presented one of the first compilations of damage to rock tunnels due to earthquake shaking. They collected information on 71 tunnels and compared their behavior with estimated peak ground accelerations (PGAs) and peak ground velocities (PGVs). Their conclusions can be summarized as follow:
Collapse of tunnels from shaking occurs only under extreme conditions.
No damage occurred when PGAs were lower than 0.19 g and/or PGVs were lower than 0.2 m/s.
Minor to moderate damage occurred when PGAs were up to 0.5 g and PGVs up to 0.9 m/s.
Moderate to heavy damage occurred when PGAs were larger than 0.5 g.
Tunnel collapse only occurred associated with movement of an intersected fault.
Tunnels are much safer than above ground structures for any given event. Several additional reviews of tunnel performance during earthquakes have been published since Dowding and Rozen (1978), including Powers, Rosidi, and Kaneshiro (1998), and being particularly important the reviews performed after large earthquakes in Taiwan (Wang et al., 2001), Japan (Kosugi, Hatsuku, & Shimonishi, 2011; Yashiro, Kojima, & Shimizu, 2007), and China (Lin & Chai, 2008; Li, 2011). These additional data points have confirmed that tunnels can actually behave quite well during earthquakes, but that their response is more complex than initially expected. Following a parallel path, several researchers were developing analytical and numerical approaches to evaluate the impact of earthquakes on tunnels and evaluate their performance, being some of the better known St. John and Zahrah (1987), Wang (1993), Penzien (2000), Hashash, Hook, Schmidt, and Yao (2001) and Hashash, Park, and Yao (2005), which was accredited by the International Tunneling Association (ITA). More detailed groundstructure approaches are also being considered and implemented as indicated among others by Corigliano, Scandella, Lai, and Paolucci (2011), Gasparini, Quaglio, and Floria (2012) and Yu, Yuam, and Bobet (2013). Currently most tunnel designers prepare initial ground support and final lining designs following static methods, advancing to the free field procedure as per Hashash et al. (2001), and moving to a full dynamic ground-structure interaction model when the seismic hazard is high.