Special features in tendering, award and contract - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 344

9.3.2 Examples: Adler Tunnel, Sieberg Tunnel, Stuttgart Airport Tunnel,
Rennsteig Tunnel, Lainzer Tunnel
Adler Tunnel. The Adler Tunnel is part of the new line Muttenz - Liestal near Basle as
part of the Bahn 2000 plan of Swiss Railways SBB. The underground part of the two-track
rail tunnel has a length of 4.3 km and an excavated diameter of 12.58 m. The geology of
the Adler Tunnel is characterised by the claystone, marlstone and limestone rocks of the
Jura (Fig. 9-3), although a third of the tunnel is located in gypsum Keuper (anhydrite, sus-
ceptible to swelling) with clay formations. In the course of the tunnel drive, extensive clay
formations had to be overcome. The hydrology of the Adler Tunnel features formation
water containing sulphates and chloride, which also tends to cause severe sintering due to
the calcium content. The water pressure was max. 1.0 bar and the water inflow 10 to 20 l/s.
Figure 9-3 Geological profile of the Adler Tunnel.
Comparative design and tendering was carried out for two variants - TBM with shield and
shotcrete tunnelling.
After a detailed analysis, the TBM option was preferred, although the initial section was
to be supported with shotcrete. One essential reason for this decision was the swelling
behaviour of the anhydrite.
The TBM drive of the Adler Tunnel was completed at the start of 1998. Early after the start
of the temporary works for the starting area by shotcrete tunnelling, a collapse occurred.
Another collapse occurred soon after the subsequent start of the TBM. During the advance
of the shielded machine, there was another collapse after 1,710 m, which led to complete
jamming of the cutterhead.
After the performance of additional works like drainage from the surface, grouting ahead
of the machine from the shield and further improvements to the machine, the shield drive
was completed without problems, with average advance rates of 15.5 m/d being achieved;
5.4 m/d was even achieved in a fault zone.
The resulting extra costs led to an arbitration process, at which all the problems that had
led to interruptions and costs were worked through with the project parties. Despite the