Dynamic response characteristics and damage evolution process of a slope-tunnel system containing parallel traversing weak interlayers based on frequency domain analysis via shaking table test

The dynamic response of slope-tunnel systems under seismic loading is complex due to the intricate interaction between the slope, tunnel, and earthquake. This work investigates these dynamics characteristics through frequency-domain analysis, focusing on key parameters including peak Fourier spectrum amplitude (PFSA), the ratio of horizontal to vertical Fourier spectral (FSR), and acceleration amplification coefficient. The shaking table tests reveal that the seismic intensity and frequency significantly influences the dynamic response and spectral characteristics of the slope. As seismic intensity increases, the inherent frequencies, MPGA, and FSR within the slope gradually decrease, while PFSA increases. Low-frequency components (0-30 Hz) primarily cause overall deformation beneath the tunnel and inside the slope, while high-frequency components (48-70 Hz) mainly induce shear band deformation on the slope surface. Additionally, this work investigated the impact of seismic waves in different directions on the spectral transformation and damage deformation of the slope-tunnel system. Vertical seismic waves mainly affect settlement deformation and crack propagation in weak interlayers and tunnel. Meantime, the vertical waves amplify the high-frequency band in the Fourier spectrum of horizontal seismic waves. Moreover, the correlation between the inherent frequencies of the slope-tunnel system and MPGA is further evaluated via Pearson correlation coefficients. The cumulative damage factors of the slope following an exponential trend. The frequency-domain analysis conducted accurately represents the seismic response characteristics of slope-tunnel systems, thereby facilitating enhanced seismic performance and structural safety of engineering designs.