Efficient formwork systems for lining road tunnels make considerable economic savings possible. If the formwork is meant to be of general use in our road tunnels, it should be adoptable to varying cross-sections and length of lining. The construction sites are often difficult to access. Therefore the formwork should be of a knock-down construction and quick to assemble. Loads on the formwork depend primarily on concreting speed, temperature, consistency, and the water-tightness of the form. In addition to this, one should also consider special stresses caused by pumping and vibration of concrete. A basis for dimensioning the forms is shown in fig. 1. Formwork carriages (fig. 2) with form vaults being manoeuvred by hydraulic jacks are flexible, allow plant traffic pass through and make rapid lining progress. They may only be used when concreting long tunnel linings, owing to the purchase costs and the time consuming assembly. A cheaper formwork carriage is presented in fig. 3. The form is constructed of struts and shores which make the form adaptable to all types of cross-sections and lengths of tunnel linings. The wooden form panels are made to a fixed cross-section. This knock-down construction simplify the transport, repair as for ordinary formwork carriages. When concreting in tunnels is not in progress, the elements may be used in other types of formwork. Wheeled form vaults have been used in Norway when concreting motorway tunnels. The economical results have been satisfactory. Two different principles of form lowering and--raising have been used. One is based on conical wheels, being forced towards the lining or vice versa by means of double-acting hydraulic cylinders and a rigid connection between wheels and cylinders, see fig. 5. The other is based on levelling screws (fig. 4), and will not, as opposed to the first mentioned, block up the passage through the form. Formwork vaults are efficient to use but are tailor-made to a specific tunnel cross-section, which reduce the application. /Author/

  • Corporate Authors:

    Norwegian Road Research Laboratory

    Postboks 8109, Gaustadalleen 25
    Oslo,   Norway 
  • Authors:
    • Larssen, T L
  • Publication Date: 1975-9


  • Norwegian

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Subject/Index Terms

Filing Info

  • Accession Number: 00131568
  • Record Type: Publication
  • Report/Paper Numbers: No. 48
  • Files: TRIS
  • Created Date: May 14 1976 12:00AM