The economic use of boom-type tunnelling machines is restricted by the time taken for erection of supports. The article describes an open invert shield developed by Markham for use in conjunction with heavy-duty road heading machines. The machine takes the form of a walking horseshoe-shape shield or canopy designed for operation in an 18 x 16 ft NCB road heading. The distance between the face and the first permanent support erected is designed to be 3.6 M with a distance of only 2.0 M from the face to the front of the tunnelling shield. Advantages offered by the canopy are - a safe working environment; control of the strata, increased rate of advance and mechanisation of support arch setting. The equipment provides a method of setting lagging inside a steel skin said to give 15-times the flexure strength of standard arches set side by side. (TRRL)

  • Availability:
  • Corporate Authors:

    Morgan-Grampian Limited

    30 Calderwood Street
    London SE18 6QH,   England 
  • Publication Date: 1980-7

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00325122
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Sep 16 1981 12:00AM