After more than 1000 years of unloading effects, the roof of Beishan Cave 168 at Dazu Rock Carvings is riddled with intersecting cracks, posing significant structural stability problems. At present, the cave roof is temporarily supported by materials like steel plates and pipes, but cracks continue to spread, and the steel plates are severely corroded, leaving the cave at risk of instability and collapse. Emergency reinforcement and protection are urgently needed. Due to the cultural importance of the site, the reinforcement process must minimize disturbance, necessitating continuous monitoring throughout construction. This paper uses numerical simulation to analyze the deformation mechanism under existing support conditions, guiding the placement of monitoring points. Monitoring data from the entire construction process are analyzed to evaluate the engineering treatment. The results provide valuable insights for monitoring and protecting similar structured grotto roofs.

In order to study the energy absorption characteristics and dynamic response rule of constant resistance and large deformation with negative Poisson’s ratio (NPR) anchor cable under the action of earthquake, the physical model test on the tunnel passing through a fault supported by common anchor cable and NPR anchor cable was carried out by using the shaking table test. The dynamic response rule of tunnel structure under different surrounding rock conditions and supported by different anchor cables under the action of earthquake was compared and analyzed. The results show that the damage degree of tunnel structure supported by NPR cable is significantly improved compared with that supported by common cable under the same seismic wave. This suggests that NPR cable has good energy absorption characteristics and can provide effective support for tunnel structure under earthquake. By comparing and analyzing the time-history curves of axial force of common cable and NPR cable, it is evident that under the action of seismic waves, the common cable will break and the axial force will drop to zero, while the high constant resistance of NPR cable can continue to provide effective support. By analyzing the dynamic response of acceleration, strain and earth pressure at each measuring point of the tunnel structure, it can be seen that the dynamic response of the tunnel fault area is more obvious, and the tunnel structure fails in the sequence of arch spandrel→haunch→crown under the action of earthquake. This research achievement provides a theoretical reference for support strategies in tunnel engineering.