Centrifuge Model Study of Impact on Existing Undercrossing Induced by Deep Excavation

A 33-meter deep excavation with multi-level struts for a ventilation shaft of Shanghai metro line 9 was simulated by a series of centrifuge model tests at Tongji Centrifuge Laboratory in 100g acceleration filed to study its impact on an adjacent undercrossing and the effect of barrier piles-wall installed between them. The draining-fluid method was used to simulate the process of excavation while a new hydraulic-control device to simulate the installation of multi-level inner struts in-flight was developed. The observed settlements of undercrossing in tests were compared with those obtained in field monitoring in the first place. Then the behaviours of the undercrossing in tests differing in parameters of barrier piles-wall were analyzed. Finally, the impact range of the excavation and the recommended geometric parameters of barrier piles-wall were discussed.