Tunnel size effects
Abstract
Unfortunately, it is not so frequently that a large diameter TBM follows a small diameter TBM through the same rock, without the ‘benefit’ of the reduced volume to excavate, caused by the pilot tunnel preceding it. If there is a ‘normal’ distribution of rock quality, the large TBM will encounter a longer total length of rock requiring temporary (and permanent) support than the smaller TBM. This will tend to increase gradient (–) m in these zones, and tend to give a slightly higher overall average gradient as a result.
Fields of Study & Subjects
Tunneling and Rock Mechanics
Geotechnical Engineering and Analysis
Geotechnical Engineering and Underground Structures
Publication details
- Journal / source
- CRC Press eBooks
- Pages
- 88–90
- Publication date
- 19 January 2026
- Language
- EN
- Document type
- Book chapter