Deformation of existing metro tunnels under close and complex construction disturbances: Case study

Abstract

This paper investigates deformation mechanisms of operational metro shield tunnels induced by adjacent collinear excavation through a case study of the Hangzhou Grand Convention & Exhibition Center project. A 31-month monitoring program systematically captured tunnel displacement evolution, diaphragm wall deformation, and ground response under spatially complex conditions where excavation zones intersected parallel metro tunnels. Three principal findings emerge: Phased excavation sequences govern cumulative deformation patterns, with tunnel uplift driven primarily by stress redistribution during progressive basement excavation; Interactions between adjacent excavation pits exacerbate localized displacements near tunnel intersections, underscoring the necessity for adaptive structural countermeasures; Deformation progression exhibits significant temporal dependency, with sustained collinear unloading phases contributing disproportionately to total displacements. Post-construction monitoring data confirm stabilization trends attributable to optimized zoned excavation strategies and proximity reinforcement interventions. This study provides the basic data of tunnel deformation development and a practical framework for mitigating deformation risks in urban excavation projects interfacing with metro infrastructure.