Abstract: This paper presents a case history of deep excavation design in soft soils with irregular supporting shape and close to an active metro line. The site-specific engineering and hydrological conditions, irregularity of the site on the plan view, and the excavation and supporting sequences due to the adjacent active metro line are comprehensively considered for an optimized excavation supporting solution. The supporting structure type and structure design details, access trestle arrangement and the construction impacts on the active metro line are discussed in the paper. Measures that could control the deformation of the supporting structures were implemented in the construction, the rehabilitation of the ventilation shaft of the active metro and the connection underpass were constructed after the completion of the deep excavation so that the safety of the metro operation was maintained. The predicted deformation values were also compared with the construction monitored values. The comparative values indicated that the excavation design and construction are successful.

Key words: excavation adjacent to active subway line, deep excavation with irregular support shape, layout of access trestle