Impact of activating a reserved metro interface on existing tunnels and station after long-term operation: Dynamic response and safety assessment

The delayed activation of reserved metro interfaces after long-term operation poses significant geotechnical challenges that remain poorly understood. This study develops a novel “long-term consolidation” framework, integrating 12-year stratum evolution and residual structural stresses into a refined 3D finite element model. Simulation of 19 dynamic construction stages reveals maximum displacements of only 2.0 mm for the station and 1.8 mm for the tunnel, along with a maximum crack width of 0.06 mm—all well below Chinese code limits. The proposed method improves displacement prediction accuracy by 25% compared to conventional static models, providing a validated technical framework for urban metro renewal projects.