The results of tests with a full face tunnelling machine using high pressure water jets in conjunction with roller cutters are discussed. It is shown that it is possible to either reduce the thrust or increase cutter speed and lower cutting costs. Tests have shown that full face tunnel boring in coal can successfully be supported by high pressure water jets reducing static forward thrust as well as cutter head torque by at least 40 to 50 per cent. Water jet assistance must be applied to the whole cutter head radius. For the same power consumption, a few larger nozzles are more effective than a larger number of smaller jets. Nozzle diameter should be smaller than 0.25 mm. The stand-off distance between nozzles and tunnel face must be at least 35 mm to avoid damage. Water pressure must be between 3000 and 4000 bar for satisfactory cutting. Cutting forces on the roller cutters are higher in the centre of the head. Selected concentration of water jet assistance on the head could make more effective use of the high pressure water. /TRRL/

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Filing Info

  • Accession Number: 00302008
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Report/Paper Numbers: Supplement
  • Files: ITRD, TRIS
  • Created Date: Dec 19 1979 12:00AM