Tunnel Boring Machine 'Annie' passing through ventilation shaft during excavation on the Channel Tunnel Rail Link.
Once a Tunnel Boring Machine (TBM) is launched and excavating, it's unusual for anybody (other than the tunnelling crew) to see it again until the tunnel is completed. However, there was a rare glimpse of TBM 'Annie' as she passed through an underground ventilation shaft during her drive from Stratford to Kings Cross on the Channel Tunnel Rail Link in London. The C220 tunnels are the longest section of bored tunnels on the CTRL and the longest earth pressure balance driven tunnels on this scale in the world. Earth Pressure Balance Machines (EPBMs) are tunnel boring machines specially designed for operation in soft ground, particularly in areas containing water under pressure. EPBMs are utilized in the construction of rail tunnels, metropolitan subway systems, highway tunnels and other projects where the tunnel will be constructed either partly or completely in soft soil beneath the water table. Loose sedimentary deposits with large boulders and a high water table will challenge ordinary TBMs, but not EPBMs because they have an articulated shield that is sealed against the pressure of water inflows. EPBMs control the stability of the tunnel face and subsidence of the ground surface by adjusting the pressure inside the cutterhead chamber to achieve a balance with the pressure in front of the cutterhead. This allows the working area inside the EPBM to remain sealed against the fluid pressure of the ground outside. The £ billion Channel Tunnel Rail Link (now High Speed One) was built between 1998-2007 and partly funded by the European Union, it forms a section of the Trans European Rail Network. It is basically a French-style high-speed rail line linking London with the Channel Tunnel, the Eurostar trains were developed on proven technology from the French TGV high-speed system.
Size: 2704px × 4064px
Location: Islington, London, UK
Photo credit: © qaphotos.com / Alamy / Afripics
License: Licensed
Model Released: No
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