Seismic Dynamic Response Analysis of Mountain Tunnels with Seismic Reduction and Isolation Measures

In this paper, the multi-domain indirect boundary element method (IBEM) is developed for the seismic response analysis of double-line mountain tunnels with seismic reduction and isolation measures. The dynamic response of the tunnel with seismic reduction and isolation measures under incident SV waves is analyzed, and the effect of the mountain topography on the tunnel is also investigated. Further, the effects of the isolation layer and the grouting reinforcement with different thicknesses on the seismic response of the tunnel are discussed in detail. The results show that the scattering of seismic waves by mountain topography significantly increases tunnel stress. In general, with the increase of incident frequency, the isolation layer will increase the peak displacement of the tunnel by about 12.7% at most, and the isolation ratio of the isolation layer on the tunnel stress exceeds 40%. The seismic reduction performance of the grouting reinforcement also depends on the incident frequency, and the amplitude decreases by approximately 20% at most frequencies. However, it is possible that the lining displacement under high-frequency waves becomes larger. This method can provide valuable insights and assessments for damage prediction.