Shaking Table Test of Seismic Effects of a Fault Tunnel Supported by Anchor Cables with Negative Poisson's Ratio

Western China is located at the junction of the Eurasian Plate and the Indian Ocean Plate, resulting in the development of fractured zones and high seismic risk. Tunnel construction in this region often crosses fault zones, making it crucial to study the seismic support system for fault tunnels. Therefore, a physical model test using a shaking table was performed. The experimental results showed that under seismic action, ordinary anchor cables are pulled apart and fail because of cracks, while negative-Poisson's ratio (NPR) anchor cables experience energy absorption slip, ultimately leading to collapse and instability. The NPR anchor cable support system has good energy absorption and seismic resistance behaviors. In contrast, the Poisson's ratio anchor cable is broken in the time range 1,200-1,400 s, with the breaking time in the fault zone advanced to <1,200 s. Through numerical analysis and model testing, we observed that NPR anchor cables significantly inhibit the amplification effect of acceleration compared to ordinary anchor cables. Their energy absorption capability helps reduce the impact of seismic actions on the rock surrounding the tunnel. These experimental and numerical results offer a valuable design basis for future seismic support engineering of fault tunnels.