Observed differences in the behaviour of London Clay sub-units during SCL works for Bond Street Station and Tottenham Court Road Station (C300/410)

BFK (BAM, Ferrovial, Kier joint venture) was awarded Crossrail contracts C300/410 in January 2011, this included 6.4km of twin bore tunnels between Royal Oak Portal and Farringdon, two new underground stations at Bond Street and Tottenham Court Road, a crossover at Fisher Street and six running tunnel cross passages. Donaldson Associates Ltd, in conjunction with IGT, were appointed as Contractor’s SCL Designer.

The Sprayed Concrete Lining (SCL) excavation works at Bond Street and Tottenham Court Road have formed the main focus of this paper. The works have provided an opportunity to observe first-hand the mechanical behaviour of the ground during construction. These observations combined with geotechnical ground investigation information obtained prior to construction and in-tunnel convergence monitoring obtained during construction enable an understanding of mechanics responsible for the observed behaviour.