Microtunnel Le Corbusier / Ø1500 EC pipeline (Switzerland)

27 juillet 2023

Tunnels and underground structures

• Project Owner: Ville de Genève – Service du Génie civil
• Mission: Maîtrise d’œuvre
• Cost of the works : 4’500– kCHF
• Cost of the mission : 250’000,–kCHF
• Mission date : 2013-2015

BRIEF DESCRIPTION AND CHARACTERISTICS OF THE PROJECT

The project involves building the final section of the large-capacity (Ø150 cm) intercommunal transport tunnel, which will collect rainwater from the Florissant-La Garance catchment area, in the Malagnou district: Rue Le Corbusier – Chemin de la Boisserette – Chemin de la Chevillarde section.

Given the considerable depth of the collector (between 4 and 9 metres) and the presence of poor-quality soil below the surface water table (loam and clay that is poorly consolidated or even free-flowing), the project study led to the adoption of a trenchless excavation method, using a microtunnelling machine with the containment head held in place by bentonite pressure.

This technique is the most suitable solution from a technical and economic point of view, allowing in particular a significant reduction in the impact of the work on the surface (site noise, volume of earthworks, felling of trees, hindrance to road traffic).

The main constraints of the project were as follows:

• Work to be carried out in a public and private urban environment, where the impact of the site at all levels had to be limited.
• Construction of the firing and reception cells for the microtunnelling machine, the drop shafts, and the installation of site facilities, mostly on restricted areas with landscaping and equipment to be protected or restored after the works.
• Deformable ground beneath the water table, with existing buildings nearby, and small deviation tolerances for the height of the route.

Technical specifications

• Demolition work
• Sheet piling (1100m2)
• Jetting columns Ø800 ground improvement (1800ml)
• Hydraulic jacking of the Ø1500 collector using a microtunnelling machine: 250ml (first shot); 165ml (second shot in a curve, radius of curvature 1500m).
• Ø1400 collector in open trench 4-6m deep (20m)
• Reinforced concrete chambers, 8m deep: concrete (400m3) Reinforcement (56T)
• 2 Ø250 private connections by directional drilling (20m)
• Roadway repairs

MISSION

As a civil and geotechnical engineer, GEOS carried out a project management mission including the following services:

• Invitation to tender,
• Execution project,
• Works management. Supervision of works,
• Commissioning and completion.

CIGEO – Bure (55)

27 juillet 2023

Tunnels and underground structures

• Project owner : ANDRA
• Mission : Etudes d’esquisse, AMO des phases APS et APD
• Mission date : 2012-2017

SUMMARY DESCRIPTION AND CHARACTERISTICS OF THE PROJECT

The study carried out by GEOS Ingénieurs Conseils is part of the underground radioactive waste disposal project.

The technical characteristics of the project are as follows: construction of 2 x 4 km descent tunnels, 4 x 550 m shafts and 200 km of underground storage galleries and cells at a depth of 500 m in the Callovo-Oxfordian clay.
The minimum operating life is 100 years.

MISSION

GEOS is carrying out the following tasks:

• System project management: design studies for the civil engineering of the underground structures;
• Assistance to the project owner for the APS and APD phases.

Line 15 of the « Grand Paris Express » metro system – Villejuif Louis Aragon – Pont de Sèvres section

27 juillet 2023

Tunnels and underground structures

• Project Owner : SOCIETE DU GRAND PARIS
• Project management : GROUPEMENT SETEC/INGEROP
• Mission : Etudes de conception en phases AVP et PRO
• Cost of the mission : 868 k€ (Tranche ferme)
• Mission date : 2013-2018

BRIEF DESCRIPTION AND CHARACTERISTICS OF THE PROJECT

The study carried out by GEOS Ingénieurs Conseils is part of the « Grand Paris Express » metro line 15 project.

• Technical characteristics:
  – The route studied comprises a tunnel Øi = 8.8 m, 4000 m long, dug with a tunnel boring machine, including three passages under the Seine,
  – This structure is located in the geological context of the Senon chalk,
  – Construction of the tunnel boring machine entrance shaft, Pont de Sèvres and Issy RER stations and ancillary structures.

MISSION

GEOS is a subcontractor of INGEROP.

GEOS is participating in the civil engineering project management for the western section of lot 3 between Pont de Sèvres and Fort d’Issy/Vanves/Clamart.

GEOS carried out the pre-project and project studies.

These studies covered the following points in particular:

• Geotechnical design of the stations;
• Geotechnical design of the excavated tunnel;
• Interaction with existing structures.

Mont Sion tunnel – A41 North motorway – Geneva – Annecy section (74)

27 juillet 2023

Tunnels et ouvrages souterrains

• Project Owner : ADELAC (Concessionnaire de l’autoroute A41 Nord)
• Mission : Assistance à Maîtrise d’Ouvrage
• Cost of the mission (projet global) : 187 k€ HT
• Mission date : 2006-2008

SUMMARY DESCRIPTION AND CHARACTERISTICS OF THE PROJECT

The study carried out by GEOS Ingénieurs Conseils is part of the construction of the A41 North motorway, section Geneva (Switzerland) – Annecy (Haute-Savoie – France).

The characteristics of the project are as follows:

• 3000 m long twin-tube tunnel,
• Tunnel excavated by tunnel boring machine Ø = 11.80 m in molasse.

MISSION

GEOS provided assistance to the project owner, including :

• External control of the design studies (EPOA, APOA) ;
• Preparation of approval decisions
• Auditing of execution studies and works;
• Providing expert advice to the Technical Department.