Seismic model test research on the combination of rigidity with flexibility of tunnel portal in high intensity seismic areas

Abstract

Taking the soft rock portal section of the Baiyunding Tunnel as the research background, it is proposed that the combination of rigid and flexible anti-vibration measures can more effectively improve the seismic performance of the tunnel. Through shaking table model test, the seismic effects of structural reinforcement, installation of shock absorbing joint, and the combination of rigid and flexible anti-vibration measures are compared and analyzed. The test data shows that: only structural strengthening measures are taken, the minimum increase percentage of the structural safety factor of the tunnel portal section is between 30.40% and 62.28%; only shock absorbing joint are installed, and the minimum increase percentage of the safety factor of the tunnel portal section is between 41.86% and 53.30%; the combination of rigid and flexible anti-vibration measures is adopted, the minimum increase percentage of the structural safety factor of the tunnel portal section is between 85.20% and 140.99%. The combination of rigid and flexible anti-vibration measures has a significant effect on resisting earthquake vibration and reducing forced displacement, and the effect of shock absorption is the best. The research results can provide a reference for improving the seismic performance of traffic tunnels in high seismic intensity areas.

Keywords

• high intensity seismic area
• tunnel portal section
• model test
• shaking table
• minimum safety factor