GEOTECHNICAL ASPECTS OF TUNNEL CONSTRUCTION FOR THE DINORWIC POWER STATION

The main underground excavations in a folded and faulted sequence of purple, red and grey-blue cambrian slates interbedded with coarse, indurated sandstone beds is described, and the geology around the proposed caverns is illustrated. The report discusses geotechnical aspects of tunnelling in slate, and outlines the geotechnical data recording and prediction. The stability of old, 19th century railway tunnels was examined and found to correspond to stability conditions in the exploratory and access tunnels. It was found that discontinuities approximate to planes but deviate slightly with an amplitude of a few centimetres in about 15 metres. Considerable overbreak occurred when the tunnels were driven along or almost along the strike of the cleavage and hence along the most persistent of the near-vertical discontinuity sets. Most block failures from the roofs and walls of tunnels occurred at the time of blasting, and hand-scaling was carried out from the muckpile immediately after fume clearance. Post-blast loosening was more common in some rock types than in others. Tunnel records, together with detailed geological mapping in and around the Dinorwic Quarry and observations at the slate quarry to the north allowed a continuous updating of the contractors geological plans and sections.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00174653
• Corporate Authors:

  Foundation Publications Limited

  7 Ongar Road
  Brentwood CM15 9AU, Essex,   England 
• Authors:
  • Whittle, R A
• Publication Date: 1977-1

Media Info

• Features: Figures;
• Pagination: p. 15-20
• Serial:
  • GROUND ENGINEERING
  • Volume: 10
  • Issue Number: 1
  • Publisher: EMAP CONSTRUCT LIMITED
  • ISSN: 0017-4653

Subject/Index Terms

• TRT Terms: Data collection; Electric power plants; Excavation and tunneling; Excavations; Failure; Faults; Forecasting; Geology; Geotechnical engineering; Sandstones; Slate; Surveying; Tunneling
• Old TRIS Terms: Data recording; Underground surveying
• Subject Areas: Bridges and other structures; Geotechnology; Highways;

Filing Info

• Accession Number: 00156065
• Record Type: Publication
• Files: TRIS
• Created Date: Feb 16 1978 12:00AM