THE VALIDITY OF GEOLOGIC PROTECTION: A SUCCESSFUL EXAMPLE: THE STRAIGHT CREEK TUNNEL PILOT BORE, COLORADO

Projection of details of surface geology to depth prior to construction has met with only limited success in many tunneling operations. In the Straight Creek Tunnel pilot bore good results were obtained by making predictions of the extent and kinds but not of the exact locations of conditions that could be expected at tunnel level based on a statistical study of surface features. Successful predictions were made regarding percentages of rock types, linear feet of faulted and sheared rocks, and attitudes of foliation and fractures, including faults and joints. Predicted rock loads and final small pressures to gouge and altered rocks agreed well with actual measurements. Ground-water flows were encountered in expected amounts, but criteria for estimations proved to be unsound. Estimates were made of the amount of temporary support, footage of exploratory feeler holes, and amounts of grouting, and provided a sound basis for estimating total tunneling costs. /Author/

  • Corporate Authors:

    U.S. Geological Survey

    F Street Between 18th and 19th Street, NW
    Washington, DC    20244
  • Authors:
    • ROBINSON, C S
    • Lee, F T
  • Publication Date: 1965

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 65 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00263307
  • Record Type: Publication
  • Source Agency: Geoscience Abstracts
  • Report/Paper Numbers: #803
  • Files: TRIS
  • Created Date: Dec 19 1974 12:00AM