Dynamic response of mountain tunnel, bridge, and embankment along the Sichuan-Tibet transportation corridor to active fault based on model tests

The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes. While extensive studies have individually explored the effect of active faults and strong earthquakes on different engineering structures, their combined effect remains unclear. This research employed multiple physical model tests to investigate the dynamic response of various engineering structures, including tunnels, bridges, and embankments, under the simultaneous influence of cumulative earthquakes and stick-slip misalignment of an active fault. The prototype selected for this study was the Kanding No. 2 tunnel, which crosses the Yunongxi fault zone within the Sichuan-Tibet transportation corridor. The results demonstrated that the tunnel, bridge, and embankment exhibited amplification in response to the input seismic wave, with the amplification effect gradually decreasing as the input peak ground acceleration (PGA) increased. The PGAs of different engineering structures were weakened by the fault rupture zone. Nevertheless, the misalignment of the active fault may decrease the overall stiffness of the engineering structure, leading to more severe damage, with a small contribution from seismic vibration. Additionally, the seismic vibration effect might be enlarged with the height of the engineering structure, and the tunnel is supposed to have a smaller PGA and lower dynamic earth pressure compared to bridges and embankments in strong earthquake zones crossing active faults. The findings contribute valuable insights for evaluating the dynamic response of various engineering structures crossing an active fault and provide an experimental reference for secure engineering design in the challenging conditions of the Sichuan-Tibet transportation corridor.