Assessing building damage during station break-out in urban railway construction: real monitoring data

The rapid expansion of urban railway networks has necessitated the extensive construction of underground stations within densely populated urban environments, where adjacent buildings are often situated in close proximity to excavation zones. Among the various stages of underground station construction, the station break-out phase—during which the tunnel boring machine (TBM) transitions between the station box and the running tunnel—represents one of the most critical and high-risk operations. This phase is characterized by complex ground–structure interactions, abrupt alterations in stress redistribution, and an elevated likelihood of ground deformation. Such conditions may induce adverse effects on surrounding structures, including cracking, differential settlement, and, in extreme cases, partial or complete structural failure. Despite notable advancements in excavation technologies and ground improvement techniques, unforeseen damage to nearby buildings continues to be reported, underscoring the limitations of existing predictive approaches and the need for enhanced analytical frameworks. Accordingly, this study aims to investigate the underlying mechanisms and contributing factors associated with building damage during station break-out operations, while proposing more robust strategies for risk mitigation and infrastructure protection in urban tunneling projects. The findings reveal a strong interdependence between the stability of excavation chamber pressure and the magnitude of ground response, thereby highlighting the critical importance of rigorous face support control, alongside the implementation of continuous, high-resolution monitoring systems to ensure construction safety and minimize structural impacts.