The four TBMs for the 13.5km-long HS2 Northolt Tunnels beneath London constructed tunnels with internal diameters of 8.10m (Northolt Tunnels East) and 8.8m (Northolt Tunnels West). In addition to 34 standard cross-passages between the upline and downline tunnels, 12 adits connect to the shafts, three of which are large diameter openings.
To minimise impact on tunnel logistics, reduce overall construction time and improve safety, Skanska Costain Strabag JV (SCS), working with HS2 Ltd, designed the tunnel connections to be constructed without conventional temporary works such as propping, temporary steel framing, or installation of SGI rings around openings. Instead, specially developed opening sets using special concrete segments were used. These incorporated corrosion-protected cast-in steel components that ensured highly rigid and durable connections between ring joints.
In accordance with the HS2 project requirements, the special segments underwent pre-installation testing under both fire and sustained loading conditions.
The lecture, to be held on Thursday, January 15, will be delivered by SCS’s head of tunnels, Michael Greiner; Strabag’s TBM tunnelling design lead, Dominik Hoerrel; and Typsa’s senior TBM tunnel designer, Xavier Torello Ciriano.
The event will be held at, 18:00 (GMT+1) at the Institution of Civil Engineers, One Great George Street, London SW1P 3AA and streamed live.
