Comparative Analysis of Dynamic Responses of Different Rock Tunnel Slopes

Large-scale shaking table tests and numerical simulations are performed to analyze the commonality and difference of the seismic responses between two rock tunnel slopes. One is a slope with a single tunnel, the other is a slope with small spacing tunnel, and both have the same slope size and tunnel size. Two recorded ground motions with different amplitudes are applied in three directions. The results show that the acceleration amplification effect of two slopes both presents obvious nonlinear characteristics along the height of slope. The acceleration amplification effects of two slopes mainly appear at the middle-upper part of slope under horizontal seismic excitation, whereas those mainly appear near the slope crest under vertical seismic excitation. Whether in horizontal or vertical excitation direction, the acceleration amplification effect of the slope containing small spacing tunnel is greater than that of the slope containing single tunnel. There is a significant difference in seismic response between small spacing tunnel and single tunnel. The maximum horizontal displacements of two slopes are on the slope crest. With the increase of the input earthquake amplitude, the peak displacement of the slope containing small spacing tunnel is gradually approaching and exceeding that of the slope containing single tunnel. The arch springing, the tunnel vault, the middle rock pillar and the slope foot of the slope containing spacing tunnel require special enhancements for seismic design, whereas the special reinforcement area of the slope containing single tunnel is the arch springing and the tunnel vault.