Contractors f Salzburg, Austria, encountered very bad geology - heavily distorted, preloaded rock under an overburden up to 3,300 ft (1,000-m) thick. After crossing a zone of almost cohesionless talus at the northern entrance, the major extent of the highway tunnel advanced into heavily distorted, tectonically preloaded phyllites under an overburden of up to 3,000-ft. The difficult construction task, comprising the first of twin-tube tunnels, connecting tunnels and ventilation shaft and cavern, relied throughout on the New Austrain Tunneling Method (NATM). Described herein are the overriding importance of system anchoring which could be adjusted to meet all conditions, and of the less effective but also necessary shotcrete lining. A new way of subdividing the latter had to be introduced to accomodate without damage to the lining the large deformations required to reduce the heavy rock pressure. /ASCE/

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  • Accession Number: 00131709
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 14 1976 12:00AM