FIELD STUDY OF TUNNEL PREREINFORCEMENT-CLOSURE

The authors reply to discusser's comments. It is noted that the use of steel sets in relatively competent ground can be ascribed to design conservatism on account of the difficulties encountered during the construction of the first bore and some questions as to the competence of the reinforcement system. The orientation of joints relative to the spiling is discussed, and the authors comment on the discusser's preference for longer bolts, steeper installation angles, and prestressed bolts. Excessively long bolts do little to improve the opening stability. Spiles installed at a steeper angle from the horizontal will result in a thicker arch. Spile installation should not only be related to geologic features but also to the response of the rock mass upon excavation. The installation angle (for angles greater than 20 degrees) and use of prestress probably has a minor effect on the mode by which reinforcement stabilizes the rock mass especially when compared to factors such as position and time of installation and method of installation (fully grouted versus mechanically anchored).

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Filing Info

  • Accession Number: 00310723
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13948
  • Files: TRIS
  • Created Date: Oct 8 1980 12:00AM