ABSTRACT
The dynamic responses of the ultra-shallow embedded tunnel, like GPST (ground penetrating shield tunnel), remain unclear compared to regular shield tunnels. In this paper, large-scale shaking table tests are performed to investigate the dynamic responses of the GPST. The physical model is designed to reproduce the system composed of tunnel launching and arrival at the ground level. The buried depth of the model tunnel ranges from -0.5D to +0.5D. The site-specific earthquake motion is adopted as seismic excitations along the transverse direction. The acceleration response, diameter deformation ratio, joint extension and dynamic earth pressure are investigated to reveal the dynamic characteristics of GPST. The results show a significant correlation between dynamic response and buried depth. In terms of acceleration response, the acceleration response increases with the decrease of the buried depth. Specifically, the acceleration of the tunnel at the shallowest buried depth reaches four times the input motion. Moreover, the structure has the ‘whiplash effect’; the overground structure oscillates violently due to earthquakes. However, the diameter deformation and joint opening response are opposite, showing that the diameter deformation response gradually increases with burial depth.
