The 9-km single-track rail tunnel is being driven through difficult and variable volcanic formations, and a description is given of the tunneling conditions, the equipment and techniques used to overcome changing circumstances. The west portal is situated in saturated alluvial deposits and a short length of tunnel through this formation was supported with multiple-stage timbering. The tunnel then passes through 5 km of andesite, which ranges from hard jointed rock to soft weathered material and associated tuffs and breccias. The formation is extensively faulted and contains zones of swelling montmorillonite clays; for much of its length temperatures of 35-40 degree C are encountered. Excavation is by full-face methods with the use of explosives, where possible, with variations of heading and bench techniques in bad ground. The high underground temperatures have been rendered tolerable by the installation of refrigeration equipment with a total capacity of 200 tonnes. The remainder of the tunnel passes through massive pyroclastic flows, material ranging from moderately hard blocky rock to weak tuffs and breccias. This section of the tunnel is being driven successfully by use of a 6.4-m diameter Jarva boring machine.

Media Info

  • Pagination: p. 371-380

Subject/Index Terms

Filing Info

  • Accession Number: 00167529
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Dec 27 1977 12:00AM