The possible influence of stress and strength ratios
Abstract
An interesting analysis of four hard rock tunnels in California was given by Klein et al. (1995) . The σ c or UCS range was 70 to 489 MPa, TBM diameters ranged from 3.4 to 4.3 m, and tunnel lengths ranged from about 2 to 5 km. The authors utilised the field penetration index (FPI) which is defined as follows: ( 2 ) https://www.w3.org/1998/Math/MathML" display="block"> FPI = thrust / cutter ( kN ) penetration rate ( mm / rev )
Fields of Study & Subjects
Tunneling and Rock Mechanics
Rock Mechanics and Modeling
Geomechanics and Mining Engineering
Publication details
- Journal / source
- CRC Press eBooks
- Pages
- 23–25
- Publication date
- 19 January 2026
- Language
- EN
- Document type
- Book chapter