Large-diameter shield tunnel crossing closely to existing metro tunnels and a residential building: A case study

In urban regions with multiple existing underground structures, the construction of a new shield tunnel can elicit intricate responses in soil-structure interactions. Here, we present an exhaustive case study of a large-diameter shield tunnel project in Shanghai, focusing on the section that closely crosses an existing metro tunnel and a residential building. Based on the in-situ data, the settlements of the ground, metro tunnel, and residual building induced by the tunneling were analyzed, and the correlations of their deformation mechanisms were discussed. The results indicate that the presence of a metro tunnel effectively mitigates ground movement. The settlement near the existing metro tunnel is significantly smaller than that in relatively remote areas. Additional displacements, settlements followed by heaves, were observed in the existing metro tunnels. Tunneling-induced settlement was also observed in the residential building, reaching a maximum of 8.92 mm facing the crossing side. Settlement along the tunneling direction decreased notably for residential buildings, primarily owing to the reinforcing effect of the existing metro tunnel. These findings underscore the importance of considering the soil-structure interaction within multiple existing underground structures during close tunnel crossings.