Effect of strong ground motion duration on the seismic response and fragility of tunnels

This study aimed to clarify the influence of ground motion duration on the seismic response of tunnels. We utilized significant duration as a measure to construct five sets of ground motion records featuring significant durations ranging from 10 s to 50 s. This approach facilitated a quantitative investigation into the effects of ground motion duration on tunnel response and fragility. Initially, the spectrum-compatible ground motion datasets corresponding to various durations were generated by selecting ground motion records based on a duration criterion and applying wavelet function superposition. Subsequently, a two-dimensional soil-tunnel system was developed, and the generated spectrum-compatible ground motions were input into this system for seismic response and fragility analyses. The results indicated that the generated spectrum-compatible ground motions exhibited high accuracy and effectively mitigated the impacts of the amplitude and shape of ground motion spectrum. As the duration increased, both the mean value and standard deviation of the tunnel's diameter deformation ratio significantly increased. This suggests that ground motion duration significantly affects tunnel response and that the associated damage mechanisms become increasingly complex. Moreover, when the seismic intensity was low, the tunnel remained in an elastic state, demonstrating a limited influence of duration. However, when the seismic intensity was sufficiently high, ground motions with longer durations could lead to more severe damage to the tunnel. The findings of this study underscore the critical importance of accounting for duration effects in assessing the seismic response and fragility of tunnels. • High-precision spectrum-compatible ground motion datasets are generated. • Seismic response and fragility of tunnels are conducted with varying durations. • Ground motions with longer duration increase the damage to the tunnel.