Geotechnics (not only) of Switzerland Major railroad constructions Gotthard base tunnel (GBT) Bastian Bommer-Denss.

Geotechnics (not only) of SwitzerlandMajor railroad constructionsGotthard base tunnel (GBT)

Bastian Bommer-Denss

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Overall context

> The new transalpine rail routes (NEAT - Neue Eisenbahn-Alpentransversale)

Content Overall context

Geological context CostsGeotechnical

problems

Bundesamt für Verkehr BAV

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Overall context

> The new Gotthard rail link (longer, flatter and faster)

Content Overall context

Geological context CostsGeotechnical

problems

Bundesamt für Verkehr BAV

(2016/17)

(2019)

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geological context

> Gotthard base tunnel – Geological profile

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Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGDie Zeit 42/2010

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Preliminary study 1992

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Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGTunnel 4/2004

- 950 m- Partially

squeezing rock -> comprising sheared and folded Serizit phyllites (cataclasite)

- 2910 m- Extreme

squeezing rock -> intensively crumbled, kakiritic mica gneisses, mica slates and mica phyllites

- 400 m- Talus material

from rockfall-> unconsoli-dated rock

- 150 - 250 m- Liquid rock with

high water pressure-> sugar-grained Dolomite

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

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Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGTunnel 4/2004

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

Content Overall context

Geological context Methode VorgehenGeotechnical

problems Ergebnisse Zeitplan

AlpTransit Gotthard AGTunnel 4/2004

TZM North

-Geotechnically trickiest section

-1 km long, with 1000 m overburden

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

Content Overall context

Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGTunnel 4/2004

Geol. exploration-Five exploratory drillings-One penetrated the entire TZM=> Intensively crumbled, kakiritic micas

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

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Geological context CostsGeotechnical

problems

Tagungsband Swiss Tunnel Congress 2008Tunnel 4/2004

Information about the danger patterns

Triaxial testsExtreme squeezing behaviourcapacity to close the cavityLoosening phenomena and caving behaviour at the face and on the fringeSecuring the cavity

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

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Geological context CostsGeotechnical

problems

Cavity support-to resist large permissible deformations of up to 70 cm radiallyDeformable steel arches (double ring) every 1 m, 66 cm or 33 cmAnchoring system with radial anchors of up to 12 m in length

Tunnel 4/2004, Swiss Tunnel Congress 2008, IUT’ 02

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Sedrun Part-Section

Content Overall context

Geological context CostsGeotechnical

problems

Choice driving method

-Conventional driving with tunnel excavators (shovels, picks and ripper teeth)

On account of squeezing rock

AlpTransit Gotthard AGIUT’02

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Situation 2010

Content Overall context

Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGTunnel 4/2004

- 950 m- Partially

squeezing rock -> comprising sheared and folded Serizit phyllites (cataclasite)

- 1000 m- Extreme

squeezing rock -> intensively crumbled, kakiritic mica gneisses, mica slates and mica phyllites

- 400 m- Talus material

from rockfall-> unconsoli-dated rock

- 150 - 250 m- Liquid rock with

high water pressure-> sugar-grained Dolomite

- Difficult Intschi zone crossed without problem with an average daily advance of 6 m by TBM (6/2004)

- Squeezing Rock Conditions Successfully Overcome: breakthrough took place nine months ahead of schedule (TZM)(10/2007)

- Piora syncline definitively and successfully mastered with an average daily advance of 10 to 12 m by TBM. The rock was stable. No deformations and no water. (2/2009)

- Firsts breakthrough in the GBT with special driving method (11/2002)

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Geotechnical problems

> Unexpected 2003

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Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGTunnel 4/2004

- Fault zone: Squeezing rock in Faido multifunction station (1/2003)

Investigating fault zone Redisposition of the FMS 24 months delay additional costs of 500 million

CHF

10. April 2023

Major railroad constructions: Gotthard base tunnel (GBT)

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Costs

> The Costs of the AlpTransit Gotthard Project (2010)

Total costs: CHF 13.157 billion (Gotthard route with the Gotthard and Ceneri Base Tunnels)

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Geological context CostsGeotechnical

problems

AlpTransit Gotthard AGKurzfassung NEAT-Standbericht 2010 / I

Thank you! Questions?