A Study on the Effect of Grouting Pressure and the Frequency Content of Rayleigh Waves on the Response of TBM Tunnel Lining

This study primarily focused on the effect of grouting pressure on the internal forces of a TBM tunnel lining under the influence of Rayleigh waves propagating in three different directions: horizontal, vertical, and inclined, based on the frequency content of these waves. Assuming undamped soil, a TBM tunnel segment from the Algiers Metro project was modeled. The analysis considered Rayleigh wave effects in the frequency range of 1 to 5 Hz on both the dynamic soil–tunnel response and the lining. Additionally, the same frequency range was used to study the influence of varying grouting pressure levels on the internal forces of the TBM tunnel lining. The results revealed that the frequency content had a greater influence on vertical and inclined waves compared to horizontal ones. This was reflected in the higher internal force values in the tunnel structure. Furthermore, the total acceleration above the tunnel was several times higher than below it in all directions, confirming the tunnel’s role as a wave damper. It was also observed that increasing the grouting pressure contributed to reducing the sagging bending moment. The hogging bending moment, on the other hand, exhibited more complicated behavior and occasionally even increased. In addition to the effect of wave frequency content, the axial force increased with increasing grouting pressure because of the consequent increase in the stiffness of the surrounding soil. These results demonstrate that the internal forces acting on the tunnel lining are significantly influenced by both grouting pressure and Rayleigh wave frequency.