To enhance the seismic performance of inclined tunnel portal sections in high seismic intensity zones,this study,based on a specific tunnel project,employed the finite difference numerical software FLAC3D to investigate the effectiveness of grouting reinforcement and vibration damping layers.Findings indicate:(1)The extreme longitudinal stress and maximum displacement occur in the intermediate transition section of the tunnel portal,while the extreme internal stress and maximum displacement are both observed at the skewback of the lining structure.(2)Compared to scenarios without anti-seismic measures,both grouting reinforcement and the implementation of a vibration damping layer reduce the differential displacement of the secondary lining.The vertical displacement difference is most significantly reduced after installing the damping layer,with a vibration reduction effectiveness of 74.83%.(3)The minimum principal stress peak is highest in Condition 1(with no measures),reaching-28.64 MPa,and decreases to-20.05 MPa after the installation of the damping layer,resulting in a vibration reduction effectiveness of 29.99%.(4)As the longitudinal length of the tunnel increases,the minimum safety factor initially decreases before increasing,reaching its lowest value at monitoring surface S3 in the intermediate transition section.The safety factor is 1.95 for Condition 1,and 2.24 for Condition 2,which although improved,remains below the safety threshold,and rises to 2.56 for Condition 3,meeting safety requirements.Considering displacement,stress,and safety factors,the adoption of a vibration damping layer demonstrates superior anti-seismic and vibration reduction performance compared to grouting reinforcement alone.The conclusions provide a valuable reference for the seismic-resistant design of inclined tunnel portal sections.
NETL
NSTL
维普
万方数据
