Tunnelling shield

The shield tunneling is a construction method of tunnel construction where the tunnel boring machine is protected by a shield ( or a mehrgliedrig ). This automatic process is primarily used for tunneling in non-stable and weathered rock formations used.

Process indicator

A tunnel boring machine for the shield tunneling has the following modules, which are with the shield, a steel tubular structure, surrounded and protected so that:

  • Degradation sign with feed and bracing
  • Facilities for the installation of support and extension work
  • Facilities for material removal ( Schutter systems)
  • Supply unit ( electricity, compressed air, ventilation, water)
  • Transport facilities for excavated material, proppant and finishing materials

The tunnel lining - usually made of precast concrete ( tubbing ) - is under the protection of the rear shield skin, the so-called shield tail installed.

Structure and Types

See main article tunnel boring machine

Steps during tunneling

See main article tunnel boring machine

Work sequences: Animation of a tunnel boring machine of alptransit.ch

Manufacturing companies and machine development

See main article tunnel boring machine

History

The shield tunneling was designed by Sir Marc Isambard Brunel, a French emigrant, Thomas Cochrane and developed for the construction of 400 m long Thames Tunnel under the Thames in London ( 1825-1843 ). He settled for the shipworm ( teredo navalis ) inspire a shell with the rasp itself - to back teeth formed shells - front digs its way and secures it behind him with a tube of endogenous calcareous secretions. She bore herself as a salt water dweller prefers to ship by timber, hence the name.

The engineer developed from this principle a design - dig forward and secure the back - which he had patented in 1818. He pursued her with an ambitious project: In the middle of London, he began to build a 400 meter long tunnel with two tubes in shield tunneling under the Thames through. His method used nor a rectangular box with open sides, next to and above the other worked in the workers at the excavation wall, while the side walls were bricked. The tunnel box was always nachgerückt a piece.

A number of technical problems and water leaks led to considerable delays and the project ultimately made ​​into a financial disaster. Although the tunnel was completed, even after almost 20 years of construction in 1843, there was no money for access roads and the route construction to pre-accession of the currently burgeoning urban rail transit. In the refurbished tunnel today passes under the metro line East London Line the River Thames.

The method was further developed by Sir Peter W. Barlow, who was commissioned in 1869 with a construction of a Thames tunnel for the London Underground. Instead of a box he used a round jacking plate, and the support was no longer masonry, but by iron segments which are bolted together - these supporting segments are the forerunners of today's tubbing. His assistant James Henry Greathead further improved the technique (Tower Subway ), and invented the eponymous Greathead shield, with hydraulic presses for propulsion and pressure to prevent water ingress.

Known projects

Selection, other examples see main article tunnel boring machine

  • City-Tunnel Leipzig ( S-Bahn rail link and main line)
  • Finne Tunnel ( New Erfurt - Leipzig / Halle ) ( Germany )
  • TRUDE ( motorway A7, fourth Elbtunnelröhre, Hamburg)
  • Wienerwald Tunnel ( railway, Austria )
Wienerwaldtunnel
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