PROGRESS ON CTRL'S NORTH DOWNS TUNNEL

This article reports on the project for constructing the 3.2km long North Downs Tunnel in Kent, using the New Austrian Tunnelling Method (NATM). The tunnel will be an essential part of the Channel Tunnel Rail Link (CTRL) Ashford, and London St Pancras. The article describes the tunnel contract, the tunnel design, the tunnel construction and lining, the monitoring regime, and progress to date. Several possible types of design were considered, but the required tunnel dimensions and the predicted ground conditions led to choosing a single-tube, large-span NATM tunnel design. Safety provisions are vital, and include high-level evacuation walkways on either side of the tunnel. Between January 1994 and October 1998, pre-construction site investigations were conducted, and 30 boreholes and 17 trial pits were excavated to determine the geology and ground conditions. Most of the tunnel will be through various types of chalk, but marl is also present. A strict environmental standard for design and construction was imposed by the legislation for the CTRL. Tunnelling began on 16 April 1999, and is being conducted from two portals, using top heading, bench, and invert excavation, using a Paurat E242 roadheader and a Liebherr 932T excavator. Monitoring allows real time analysis of ground conditions during construction.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/0041414X
• Corporate Authors:

  Miller Freeman

  Calderwood Street
  London,   United Kingdom  SE18 6QH
• Authors:
  • Thomas, T
• Publication Date: 2000-1

Language

• English

Media Info

• Pagination: p. 29-31
• Serial:
  • Tunnels & Tunnelling International
  • Volume: 32
  • Issue Number: 1
  • Publisher: Progressive Media Markets, Ltd
  • ISSN: 0041-414X

Subject/Index Terms

• TRT Terms: Boreholes; Construction; Contracts; Design; Environmental protection; Full face tunneling; Geology; Legislation; Pits; Railroad tracks; Safety; Tunnel lining; Tunneling; Tunneling machines; Tunnels
• Identifier Terms: Austrian tunneling method
• Uncontrolled Terms: Site investigation
• Geographic Terms: United Kingdom
• ITRD Terms: 3386: Austrian tunnelling method; 5711: Bore hole; 3655: Construction; 146: Contract; 9011: Design (overall design); 2444: Environment protection; 5702: Excavation pit; 3383: Full face tunnelling machine; 4053: Geology; 1556: Legislation; 1665: Safety; 5722: Site investigation; 3374: Tunnel; 3385: Tunnel lining; 8119: United Kingdom
• Subject Areas: Administration and Management; Bridges and other structures; Construction; Design; Environment; Geotechnology; Law; Railroads; Safety and Human Factors;

Filing Info

• Accession Number: 00790357
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Apr 11 2000 12:00AM