Study on Dynamic Response Characteristics of Shallow-Buried and Unsymmetrical-Loaded Double-Arch Tunnel

Due to the unique structural form of the shallow-buried and unsymmetrical-loaded double-arch tunnel, the dynamic response is quite different from that of the general tunnel. In order to obtain the dynamic response characteristics of the tunnel, a three-dimensional model of the tunnel under the condition of soft-hard-soft surrounding rock is established. The EL-Centro is taken as the loading wave, the dynamic response of the tunnel under different loading peaks and different loading directions is studied. The results of numerical simulation are verified by large-scale shaking table model test. The results show that: (1) The dynamic response characteristics of the tunnel are significant affected by the direction of seismic wave loading. The peak load has little effect on the dynamic response of the tunnel. The results of numerical simulation are similar to those of shaking table experiment. (2) The dynamic response of the lining at the bias side is intenser than that at other locations. The tunnel on the bias side has poor stability. (3) The maximum acceleration response of tunnel is 0.55 g and the minimum is 0.05 g. The maximum displacement response is 30 mm and the minimum is 5 mm. The maximum value of the maximum principal stress is 5.71 × 10³kN/m². The maximum value of the minimum principal stress is 4.7 × 10³kN/m². (4) The dynamic response of the spandrel and the arch foot of the left tunnel is relatively intense. The existing slope has a significant effect on the dynamic response characteristics of the right tunnel. The middle wall structure is more dangerous under the earthquake. The research conclusion can provide reference for tunnel design and construction.