N4.1.5 Uetliberg Tunnel

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Lawrence Hicks
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N4.1.5 Uetliberg Tunnel The world's largest tunnel bore extender (TBE), which excavates the molasse by undercutting, was commissioned on April

As already reported at the ITA 2003 in Amsterdam, a tunnel bore extender using a new undercutting technique from Wirth (Germany) was started up

ITA 2003 presentation Following the breakthrough of the initial pilot tunnel on February 20, 2003, the official start of this tunnel bore

1 N4.1.5 Uetliberg Tunnel The world's largest tunnel bore extender (TBE), which excavates the molasse by undercutting, was commissioned on April 11, As already reported at the ITA 2003 in Amsterdam, a tunnel bore extender using a new undercutting technique from Wirth (Germany) was started up successfully. ITA 2003 presentation Following the breakthrough of the initial pilot tunnel on February 20, 2003, the official start of this tunnel bore extender (TBE) was celebrated on April 11, After completion of final assembly work in the trailer and functional checks of the boring head, the TBE started excavation on April 25, Since then the world's biggest "mole" a TALPA has been boring through the 2 x 2700 m long molasse stretch under Uetliberg mountain towards Zurich. TBE commissioning: April 11, 2003 TBE Information I April/2003 page 1 from 5

Tunnel Erweiterungsmaschine bore extender Bohrdurchmesser bore diameter 14.20-14.

2 Tunnel Erweiterungsmaschine bore extender Bohrdurchmesser bore diameter m TBE: with bracing arrangement in the pilot tunnel The job of the TBE, which is about 180 m long and weighs 1000 tonnes, is to extend the diameter of the 2700 m long pilot tunnel through the Uetliberg's molasse section from 5.00 m to / m. The TBE's boring head consists of a two-piece cutterhead body and six cutter arms. The boring head rotates on the interior kelly, which is braced and positioned in the pilot tunnel and in the extended tunnel crosssection. The cutting rollers, which are offset both axially and radially from the tunnel axis, are mounted on radially movable slides on the cutter arms. Superposition of the slides' radial movement on the rotation of the boring head causes each cutting roller to follow a spiral path around the tunnel axis. Because the outermost cutter on each arm leads the rest, the face area assumes a stairstep profile that enables each cutter to shear away the molasse against an open surface by the undercutting principle. The advance is limited to a maximum length of 20 cm by the axial displacement of the rollers on the slides, which ranges from 60 to 80 cm. Shorter advances can be used where harder rock is encountered. Operating principle of the boring head TBE Information I April/2003 page 2 from 5

Undercutting Technology by Cutting rollers on radially shifted slides Between eight and ten rotations of the boring

When the six-arm head turns, the rollers are shifted from an inner to an outer boring diameter.

Then the continuously rotating head is shifted by one 20 cm advance toward the face, and boring of the next advance

3 Undercutting Technology by Cutting rollers on radially shifted slides Between eight and ten rotations of the boring head are required for an advance. When the six-arm head turns, the rollers are shifted from an inner to an outer boring diameter. When the nominal boring diameter has been reached, the slides are retracted radially. Then the continuously rotating head is shifted by one 20 cm advance toward the face, and boring of the next advance (renewed outward travel of the slides) can begin. Standard cross-section The standard cross-section of the Uetliberg's molasse stretch is m wide and m high. The excavation area is about 160 m 2. TBE Information I April/2003 page 3 from 5

Fahrbahnbreite 10.50 m Pilot tunnel (Diameter 5m) Slotted channal 14.

4 Excavation area = ca. 160 m² Abluftkanal False ceiling Excavation support Waterproofing membrane In-situ concrete lining Fahrbahnbreite m Pilot tunnel (Diameter 5m) Slotted channal m Temporary site road Hydrant pipe Prefabricated service duct Drainage main m Standard cross-section in the Uetliberg molasse stretch Types of excavation, heading progress TBE Information I April/2003 page 4 from 5

5 Further information Further information on the Uetliberg Tunnel Project is available at and Further information about undercutting is avialable at All planning and design work is being handled by a team comprising four Civil Engineers ETH Project Manager Uetliberg Tunnel Project Engineers, Uetliberg Tunnel Danlei Marti Business Engineer FH Asst. Manager of Tunnelling Division dmarti@amberg.ch Tel Michael Glättli mglaetlli@amberg.ch Tel Thomas Kobler tkobler@amberg.ch Tel Arno Solèr asoler@amberg.ch Tel W:\Aibrdata\R800\INFO AE\Anfahren TBE\TBE Information E-DM.doc DM \ R TBE Information I April/2003 page 5 from 5

Reaming Tunnel Boring Machine Undercutting Technique

Reaming Tunnel Boring Machine Undercutting Technique Hat trick in the Uetliberg Tunnel State of the art technology Reaming Tunnel Boring Machine It is a well known fact that mechanically excavated tunnels