Tunnel boring machine starting bell in Rouen

XtreeE realized this piece in partnership with GTM Normandie Center. This is a prefabrication part to make a tunneling machine bell. This technique makes it possible to pressurize the tunneling chamber of the tunnel borer within the bell, to reach the confinement pressure and thus to ensure stability of the ground behind the diaphragm wall. This variant eliminates the masses injected behind the eardrums of the structure, which eliminates the risks related to leaks of this type of plug, which can have serious consequences for the safety of people working on the site or that of neighboring works. As such, this method represents an interesting option and an opportunity to reduce risks and costs. Traditionally the bell is made of metal.

  • tunnelier impression
  • Tunnelier montage
  • tunnelierscan
  • tunnelierscan2

The bell itself is partly prefabricated and partly casted in situ. A ring with the exact geometry is printed with reservations, or “ears”, to pour a reinforced concrete and ensure its embedding in a prefabricated sail. This veil is then placed in its final position and a casting is made to fit the excavated walls. Two copies have been made, compared with a third method without printing.

The printed piece has the following characteristics: Height 50 cm and weight of 480kg i.e. 750.83m of cord with a cord of 2.5cm wide and 1cm high. The impression of a ring has a duration of 1h30. A geometric control was realized by 3D scanner.


3D design: XtreeE
Client: GTM Normandie Centre