RATIONAL DESIGN OF TUNNEL SUPPORTS--A FIELD STUDY OF SPILING REINFORCEMENT IN UNDERGROUND OPENINGS

This report covers the second phase of a two part research effort. The previous study (Technical Report MRD-2-75) largely considered the effectiveness of prereinforcement systems. From measurements and observations of the physical model behavior in conjunction with calibrated numerical model results, the mechanisms by which prereinforcement displays its effectiveness was implied, but not verified. Further investigations were required to examine and substantiate the mechanisms by which prereinforcement and, in particular, spiling reinforcement work. A field instrumentation program was designed to monitor the spiling under actual tunneling conditions. This report describes the results of two such investigations. The first was carried out at the Burlington Northern Railroad pilot tunnel and main bore near North Bonneville, Washington, and the second at the Eisenhower Memorial Tunnel, South Bore. The investigation was designed to address questions primarily related to the magnitude, distribution, and time history of the deformation induced tension and bending of spiles as a result of excavation. Deformation induced tension was shown to be the major mechanism by which spiling reinforcement displays its effectiveness, while bending was of minor significance. Results from the Bonneville and Eisenhower tunnels were compared as their size, depth, and geologic environment were significantly different. The results indicated that the reinforced arch thickness was strongly dependent on ground type, while arch capacity was largely a function of opening size, shape, and depth. Variations in the instrumentation program at each of the two field sites provided for additional findings. At Bonneville, instrumented spiles used in conjunction with extensometers furnished information on the compatibility of the strains in spiles and that of rock mass in their immediate vicinity. All instrumentation installed for the pilot tunnel was designed to also monitor rock mass behavior during excavation of the main bore. /Author/

  • Supplemental Notes:
    • This report was prepared for the Department of the Army, Missouri River Division, Corps of Engineers.
  • Corporate Authors:

    University of California, Berkeley

    Department of Civil and Environmental Engineering
    Davis Hall
    Berkeley, CA  USA  94720-1710
  • Authors:
    • Korbin, G E
    • Brekke, T L
  • Publication Date: 1977-6

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 211 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00167827
  • Record Type: Publication
  • Report/Paper Numbers: Tech. Rpt. MRD-1-77 Final Rpt.
  • Contract Numbers: DACW45-74-C-0026
  • Files: TRIS
  • Created Date: Mar 7 1978 12:00AM