A tunnel excavation in Los Angeles, California, is described in which a world record is claimed for a single day's advance in hard rock. During excavation as part of the Gathright dam flood control project, an 8ft wide by 16ft high tunnel was advanced a distance of 128ft in a 24-hour, 3-shift period. Working in limestone rock which in some sections was able to stand unsupported, three jackleg drills on a mucker mounted platform were used to drill 18-24 holes 6ft deep in the rock followed by blasting. The tunnel forms part of the underground foundation treatment which requires the construction of an 8ft thick concrete underground cut-off wall 820ft long within the left abutment of the dam's foundations. /TRRL/

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  • Corporate Authors:

    Morgan-Grampian Limited

    30 Calderwood Street
    London SE18 6QH,   England 
  • Publication Date: 1975-11

Media Info

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Filing Info

  • Accession Number: 00137508
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Oct 6 1976 12:00AM