Dynamic response characteristics of tunnel linings at varied burial depths in landslide systems under seismic loading

This paper uses shake table tests to study tunnel landslide failures in earthquake zones under four conditions: (GK1) the tunnel intersects the sliding mass, (GK2) the tunnel is perpendicular to the sliding surface, (GK3) the tunnel is positioned below the sliding surface, and (GK4) the tunnel is situated above the bedrock. The dynamic responses under the four conditions are analyzed using time-domain strain analysis methods. Additionally, from an energy perspective, the amplified Arias intensity (MIa) is employed to characterize the cumulative deformation damage of the tunnel lining. The results indicate that under four working conditions, the upper landslide region of the tunnel landslide system exhibits a "settlement-compression-shear" type of sliding failure. However, in conditions GK1 and GK2, where the lining structure is present, the tunnel lining provides additional support to the landslide, resulting in less severe damage to the slope compared to conditions GK3 and GK4. However, under conditions GK1 and GK2, the left sidewall of the tunnel lining experiences more severe damage due to landslide pressure. The maximum soil pressure and bending moment on the left sidewalls in GK3 and GK4 are only 40-60% of those observed in GK1 and GK2. In addition, based on the trend of MIa, the cumulative deformation evolution of the tunnel lining can be categorized into three stages: the initial stage (0.1-0.2 g), the progressive deformation stage (0.2-0.4 g), and the failure deformation stage (0.4-0.6 g). Further research confirms that under seismic action, the slope experiences a significant progressive catastrophic evolution. This process is characterized by typical seismic cumulative damage effects, with sustained seismic loading causing deformation and damage to gradually expand from localized areas to the entire slope. This continuous fatigue effect progressively weakens the stability of the lining structure, ultimately leading to its failure. Therefore, the deformation and damage of the slope under seismic loading pose a serious threat to the safety of tunnel linings, highlighting the need for close attention to their long-term stability. The research results provide a scientific basis for reinforcing tunnel linings in earthquake-prone mountainous areas.