Southern tube of the underground crossing in Toulon: tunnel and branches

The Southern tube of the underground crossing of Toulon (A50-A57 link) fits into a geological complex similar to the one already encountered during the construction of the Northern tube (1994-2000).

The excavation of the tunnel and of the twigs in an urban context requires preliminary support and an important face reinforcement with bolts 18m long, made of fiberglass or metal tubes (total expected length of 250 km).

The immediate support, consisting of steel arches and shotcrete, associated to an invert is implemented closely to the front.

Given the numerous difficulties (geotechnical, urban frame, protection of the existing buildings, necessity to keep the Northern tube operating), the design has been validated throughout the study by a panel of experts elected by the Equipment Ministry.

The deformation control in a dense urban site is particularly important. In order to reach the planned goals, the civil engineer contract considers applying many leveling measurements. These measurements allow interpreting and interpolating the surface deformation evolution, optimizing the implemented supporting profile, while ensuring the safety of the excavation and surrounding frame.

Terrasol’s achievements:

Global project management:

  • Civil engineering works preliminary study
  • Civil engineering works project study
  • Consultancy
  • Works supervision
Characteristics
PERIOD :  2010 - 2011
Owner : Ministère des Transports, de l’Équipement, du Tourisme et de la Mer (Transports, Equipment, Tourism & Sea Ministry)
Project Manager : SETEC TPI / TERRASOL
Main specifications :  

  • Bi-tube: cross ventilation
  • Length of the drilled tunnel: 1818m
  • Excavated section:  about 120 m2
  • Cover: 15 to 35m under water table
  • Operation amount (forecast): 245M€ excluding VAT (2003)

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