PAS DE L'ESCALETTE

This article describes the construction of the 700m long Tunnel du Pas de l'Escalettes under the limestone plateau of the Causse du Larzac on the A75 road between Cermont Ferrand, France and the motorway between Marseille and the Spanish border. The work is divided into two lots: (1) the construction of the Moulinette embankment, which will require about 400,000 cu m of material; (2) the construction of the tunnel, which includes substantial cut-and-fill work on the southern approaches and other ancillary work like the building of the portals and the rerouteing of a river near the northern entrance. The tunnel itself is being bored by drill+blast, through various types of limestone rock. Although the limestone's upper layer is reasonably homogeneous, there are many fissures and cavities lower down, so that water could be one of the most serious problems. To minimise the limestone overbreak, and thus the use of concrete, the contractors chose to use an Atlas Copco Robot Boomer, for the first time in France. They also chose to replace the initial support system of shotcrete and mesh by fibre-reinforced shotcrete, covered by a second concrete layer. These choices save considerable sums of money. The support system varies according to the ground conditions, with three basic options for rockbolting.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09568700
• Corporate Authors:

  THE MINING JOURNAL LTD

  60 WORSHIP STREET
  LONDON,   United Kingdom  EC2A 2HD
• Authors:
  • MONRO, M
• Publication Date: 1993-10

Language

• English

Media Info

• Features: References;
• Pagination: p. 331,333
• Serial:
  • WORLD TUNNELLING
  • Volume: 6
  • Issue Number: 8
  • Publisher: THE MINING JOURNAL LTD
  • ISSN: 0956-8700

Subject/Index Terms

• TRT Terms: Construction management; Drilling; Excavation; Excavations; Fibers; Limestone; Reinforced concrete; Shotcrete; Tunnel lining; Tunnels
• Geographic Terms: France
• ITRD Terms: 3666: Construction method; 3871: Drilling; 5155: Excavation (process); 4557: Fibre; 8036: France; 4131: Limestone; 4794: Reinforced concrete; 4730: Shotcrete; 3374: Tunnel; 3385: Tunnel lining
• Subject Areas: Bridges and other structures; Construction;

Filing Info

• Accession Number: 00663435
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Aug 24 1994 12:00AM