Unexpected events and their Q-values
Abstract
A case record given by Robbins (1982) although fairly extreme, illustrates the problems and delays caused by unexpected conditions. The 3.1 m diameter TBM started an 8113 m long tunnel in the USA by boring 362 m of shale in less than 1 month (AR ≈ 0.56 m/hr). The next 270 m of completely unexpected waterbearing glacial debris took 203 days (AR ≈ 0.055 m/hr).
Fields of Study & Subjects
Tunneling and Rock Mechanics
Construction Project Management and Performance
Geotechnical Engineering and Analysis
Publication details
- Journal / source
- CRC Press eBooks
- Pages
- 57–62
- Publication date
- 19 January 2026
- Language
- EN
- Document type
- Book chapter