FEA meets construction: Sprayed concrete lined tunnels connecting existing subsurface assets at London Underground’s Bank Station

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4. FEA meets construction: Sprayed concrete lined tunnels connecting existing subsurface assets at London Underground’s Bank Station

London Underground (LU)s Bank-Monument Station is a key interchange served by five LU lines and the Docklands Light Railway (DLR). The Bank Station Capacity Upgrade (BSCU) adds approximately 1,300m of new sprayed concrete lined (SCL) tunnels to the existing station complex, increasing connectivity and relieving passenger congestion. The tunnel cross-sections range from 10 to 90m² and connect existing assets from the Central line finished floor level (FFL) at -20m below ground level (bgl) down to the DLR FFL at -40m bgl. Apart from a 17-week blockade for the running tunnel tie-ins, the station was kept fully operational while construction works were taking place. This paper presents numerical modelling results of the new SCL cross passages connecting to the existing station, which is composed of a variety of materials. This includes pre-1900 cast iron segments, precast concrete segments from the 1990s, brick arched passages, and mass concrete collars. Predicted asset movements from finite element analyses (FEA) were compared against the actual asset response observed by in-tunnel monitoring systems at an early stage of the construction. Back analyses were then carried out to verify the models as work progressed.

10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)

10. Tunnelling and mining applications