Editorial: Geomechanik und Tunnelbau 3/2008

✍ Scribed by Nejad Ayaydin

• Publisher: Wiley (John Wiley & Sons)
• Year: 2008
• Tongue: English
• Weight: 26 KB
• Volume: 1
• Category: Article
• ISSN: 1865-7362
• DOI: 10.1002/geot.200890022

✦ Synopsis

No tunnelling project on method can be without some level of risk having to be managed. Even the most careful investigations usually cannot define the ground conditions to achieve a design confidence level comparable to structural design conditions.

In "deep tunnels", when the knowledge of the ground conditions is poor and where we mainly have to deal with stress release, controlled displacements must be allowed to build economically. Flexible tunnelling methods -as "New Austrian Tunnelling Method (NATM)" -provide a number of possibilities for adapting the excavation and support measures for a wide field of ground behaviour. Time for setting these measures is given.

In an "urban environment" (with "low overburden") however, the minimization of settlements and the avoidance of sudden ground failure are essential for design work and construction. The design has to consider this by suitable reserves and the site organizations have to act immediately if unexpected ground behaviour is observed.

Also tunnelling with TBM shield, particularly with "low overburden" it is essential to have a real time analysis of system behaviour and make immediate decisions for additional measures to increase safety.

For all methods the aim must be to eliminate possible hazards and to identify remaining risks at the design stage and to have suitable control and management resources to act immediately.

This issue contents some practical examples for "low overburden" tunnelling and also theoretical treatises.