M25 FEATURE: CUT AND COVER TUNNELS

The article describes the principal features of two tunnels, provided on the A10 to M11 section for environmental reasons, the 650 M long Holmesdale tunnel under Waltham Cross High Street and the 470 M long Bell Common tunnel under Epping Forest. Because both tunnels formed part of the motorway contract and resultant excavation was required for use in the earthworks, embedded walls propped through the roof construction designs were chosen. Excavation between the walls was carried out in two stages, one before and one after the roof had been constructed. Slurry trench construction was used for the outer walls of the Holmesdale tunnel with central support of a transom beam roof provided by bored piles spaced at 3 M centres. A secant pile system is used for wall construction of the Bell Common tunnel because of the high lateral pressure of over consolidated clay. The central wall constructed of contiguous pairs of bored piles at 3 M centres, supports a composite form of prestressed beam and in situ slab roof. Both contain automatic control systems for lighting and ventilation, together with closed circuit television and sensor loops for automatic surveillance. (TRRL)

  • Availability:
  • Corporate Authors:

    Plenum Publishing Corporation

    233 Spring Street
    New York, NY  United States  10013
  • Authors:
    • Hubbard, H W
  • Publication Date: 1984-2

Media Info

  • Features: Figures; Photos;
  • Pagination: p. 9
  • Serial:
    • CONCRETE
    • Volume: 18
    • Issue Number: 2
    • Publisher: THE CONCRETE SOCIETY
    • ISSN: 0010-5317

Subject/Index Terms

Filing Info

  • Accession Number: 00387502
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Aug 30 1984 12:00AM