During an earthquake, the strong interaction between the surrounding rock and lining structure causes the lining susceptible to extrusion or shear damage. To evaluate the damping effect of the shock-absorbing layer on seismic loads and mitigate the deformation-induced damage of tunnel structures in loess regions, the dynamic mechanical properties of loess seismic-isolated tunnels subjected to P-wave seismic loading were investigated. In this work, the dynamic behavior of loess seismic-isolated tunnel under seismic loads was converted into a static problem. Analytical methods were employed to derive solution for internal forces within the lining structure using a mechanical analysis model. Additionally, the impact of loess hardness and seismic intensity on the performance of the shock-absorbing layer were analyzed based on the analytical solutions. Numerical methods were then applied to examine the influence of shock-absorbing layer parameters on the mechanical properties of loess seismic-isolated tunnel subjected to P-wave loads. The results indicate that the analytical solutions, simplified numerical solutions, and theoretical results in the literature exhibit strong numerical consistency and similar trends. The analytical results demonstrate that the internal forces in the lining structure increase linearly with seismic intensity, while the effect of loess hardness on the bending moment is more complex. As the loess hardness decreases, the damping effect of the shock-absorbing layer on the internal forces gradually diminishes. Numerical analysis further reveals that reducing the elastic modulus and increasing the thickness of shock-absorbing layer significantly enhance its damping effect on the axial force, although the bending moment slightly increases. Additionally, the shock-absorbing layer effectively reduces the peak stress and strain responses in lining structure, but the peak stress at the hance position increases, with this increase becoming more pronounced as the elastic modulus of the damping material decreases. Moreover, the shock-absorbing layer significantly reduces the peak acceleration response of lining structure but also leads to increased deformation, which progressively intensifies with the thickness of shock-absorbing layer. These findings provide valuable theoretical insights for the seismic design of tunnel structures in loess regions, emphasizing the importance of balancing damping efficiency and deformation control in the lining structure.

来源平台：STRUCTURES