Influence of a Super-Large Diameter Shield Tunnel Excavation on the Lining Structure of the Metro Lines in Operation

In central areas of large cities, it is necessary to ensure the safety of the existing tunnel during the construction of a super-large diameter shield tunnel. Given the rapid development of the over-lapping tunnel excavation in recent years, detailed study of the stress and deformation responses under trains' dynamic and vibration loads when a super-large diameter shield tunnel passes through the existing tunnels is essential to improve the stability of metro lines in operation. This study presents the influence of a super-large diameter shield tunnel excavation on the existing tunnel in the Shanghai North Cross Channel project. In this study, the construction disturbance of a super-large diameter shield tunnel and the influence of trains' dynamic and vibration loads on the existing tunnel are considered. The results of numerical simulations show that there are differences in the dynamic response amplitudes of segments at different positions under the combined action of new tunnel excavation loadings and trains' dynamic and vibration loads. The strong dynamic response area of the displacement and acceleration of the lining structure is mainly located at the bottom of the segment ring. The maximum compressive stress of segments appears at the arch waist of the tunnel, and the maximum tensile stress appears in arch crown.