The problems encountered in tunnelling Melbourne's underground railway are described. Drill and blast methods were prohibited to minimize ground disturbance under the tall buildings and steel ring beams had to be inserted at 1 m intervals just behind the face. Also shotcreting of the tunnel sides within 1 m of the face was required within one hour of exposure. The tunnelling machine covered nearly 40 m/week until it hit hard rock when numerous problems arose culminating in the failure of the main bearing. This failure meant that the machine had to be completely rebuilt with a new 12 spoked head and the triple-disc cutters replaced by more efficient single discs. Front support is provided by a sliding shoe, and steering jacks on the shoe help to prevent the head dropping. Bearing design was changed, and the cutter head speed reduced from 5.2 rev/min to 3 rev/min. Gearboxes and variable speed motors have been replaced with high-torque low-speed motors. Mucking out is now by rail instead of conveyor. The new hard-rock machine can work at up to 73 m/week.


  • English

Media Info

  • Features: Photos;
  • Pagination: p. 16
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00168093
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jan 13 1981 12:00AM