Some support design details for TBM tunnels
Abstract
The potential use of direct Q -system support recommendations for TBM tunnels has been discussed in Chapters 29 and 30 . The inherently greater stability of circular, machine-excavated tunnels, and their reduced need for support is taken care of by the ‘central threshold’ Q -factoring (×2 to 5) discussed earlier and shown in Figure 49 . Outside this zone, to the right-hand side (higher Q -values), no temporary or permanent support will be required. To the left-hand side (lower Q -values), equally heavy temporary and permanent support will be required in the TBM tunnel as in the drill-and-blasted tunnel.
Fields of Study & Subjects
Tunneling and Rock Mechanics
Geomechanics and Mining Engineering
Rock Mechanics and Modeling
Publication details
- Journal / source
- CRC Press eBooks
- Pages
- 118–122
- Publication date
- 19 January 2026
- Language
- EN
- Document type
- Book chapter