Vibration wave propagation differences in straight assembled shield tunnels under different deformation conditions

During the implementation of shield tunnel construction, deformation and joint opening may arise as a result of load-induced influences. Recent research has highlighted the crucial role of segment joints in the dynamic analysis of shield tunnels, yet a comprehensive understanding of the influence of joint opening on vibration wave transmission is still lacking. To address this gap, this study established a finite element model of a shield tunnel and investigated the effects of joint opening on the transmission of vibration waves. The findings of this study indicate several important results: (a) The weakening ability of joints to vibration waves within a specific frequency range is closely related to the degree of joint opening. With increasing joint opening, the weakening ability of certain joints towards specific frequency vibration waves can increase by more than 40%; (b) The weakening effect of joints on vibration waves exhibits a significant correlation with the orientation of joint openings. Inward-opening longitudinal joints exhibit a high rate of weakening for vibration waves, while outward-opening longitudinal joints demonstrate limited weakening ability towards the vibration wave; (c) The weakening ability of segment concrete towards vibration waves is significantly weaker compared to that of joints. Hence, the inclusion of segment joints is crucial in the investigation of dynamics of shield tunnels, as they cannot be disregarded.