King's Cross underground station, London: geotechnical aspects

The redevelopment of London Underground's King's Cross St Pancras Station in central London is being carried out to increase capacity from the current 55 000 passengers per hour during the morning peak to an anticipated 82 000, following the construction of the adjacent Channel Tunnel Rail Link (CTRL) terminus. The work will be undertaken in two phases: phase I works, currently nearing completion, which comprises a new western ticket hall and upgrade of the existing tube ticket hall; and phase II, which will comprise a new northern ticket hall and tunnelled links between the existing underground stations. This paper reviews the considerable amount of geotechnical work carried out for the project and will focus principally on three key areas: (a) developing an understanding of the potential hazards related to the stratigraphy of the site; (b) the use of advanced numerical methods; and (c) the role of instrumentation and monitoring within the design and risk management process.