Two articles describe the rapid development and increased use of the slurry shield (bentonite) machine in Japan. The importance of maintaining face stability and continuous automatic transport of excavated materials from the face is discussed. Recently developed slurry shield machines are designed to supply fresh pressurised slurry to the chamber at the face, to adjust its pressure and excavate the tunnel under pressure automatically and continuously return the dirty slurry containing excavated materials. In large diameter machines, flow meters and gamma ray meters are used in conjunction with a mini-computer to continuously control the slurry composition and excavated muck volume for optimum operation. The methods of excavating cobbles and use of back fill grouting are explained. The largest shield machine in use is 10.9 M in diameter and a 12.6 M diameter mechanical shield machine is planned to start work this year. /TRRL/

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  • Accession Number: 00301957
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Report/Paper Numbers: Supplement
  • Files: ITRD, TRIS
  • Created Date: Dec 19 1979 12:00AM