Shaking Table Test and Numerical Simulation of Shield Tunnel Connecting Cross Passage

The shield tunnel and cross passage forming a spatial cross structure, is a weak link in the seismic resistance. To study the influence of the rigid and flexible connection forms on the shield tunnels in seismic response, the material parameters and proportions of the similar models in the shaking table test were determined by geotechnical tests based on the similarity theory, then the experimental structure and numerical model were established. The 15.0 Hz predominant frequency obtained from the first test was used as the input earthquake frequency in the other test conditions and numerical calculation. The seismic response of the main tunnel and the connecting crossway was studied by combining the model test and numerical calculation. The results show that the acceleration response of the stratum and structure at the same depth is basically the same, and the amplification effect of stratum acceleration is more obvious when closer to the ground. The maximum strain response occurs at the vault and arch foot of the structure when rigid connection is used in the connecting transverse passage. Flexible connection can better reduce the strain response of the structure, and the larger the input peak acceleration is, the more obvious the reduction effect is. On the cross section of the main tunnel, the position near the connection of the connecting cross-passage is susceptible to stress mutation, which is more affected with rigid connection . Shaking table test and numerical results are basically the same, the influence range of the cross channel on the longitudinal direction of the main tunnel is about 3.0 times as wide as that of the cross channel when rigid connection is adopted, while the influence range is reduced to 1.5−2.0 times when flexible connection is adopted.