Civil Engineering Reference
In-Depth Information
A tunnel with circular cross-section and a diameter of 10 m that is constructed accord-
ing to the principle of resisting support is considered. In this case large radial swell-
ing pressures acting on the internal lining are calculated at the transition from the un-
leached Gypsum Keuper containing anhydrite to anhydrite-free Gypsum Keuper in the
area of the sidewalls that lead to high bending moments (Fig. 23.13). In such a case this
unfavorable loading of the internal lining, which cannot be avoided by the arrangement
of a yielding zone in the tunnel invert, should be accounted for in the design.
23.2.4 Conclusions
The results of this study comply with observations and experience gained from tunnels
that have been constructed in the past in unleached Gypsum Keuper.
The Wagenburg tunnel, the Heslach II tunnel and the Engelbergbasis tunnel are exam-
ples of tunnels that are located in the transition zone from leached to unleached Gyp-
sum Keuper. In the Wagenburg tunnel, water inflow could not be avoided. As a result,
heaving of the tunnel due to swelling and also damages of the internal lining occurred
because the latter was not sufficiently designed against swelling pressure (Paul & Wichter
1993). After construction of the Heslach II tunnel, heaving of the tunnel and the ground
surface were observed. However, this tunnel has been in operation since its completion
in 1991 without any damage to the internal lining. In case of the Engelbergbasis tunnel
the anhydrite surface in certain zones is located in the middle of the tunnel cross-section.
This tunnel suffered large amounts of heaving and damage of the internal lining. Even
during construction, access of water was observed (Bernhardt & Rock 1995).
In the Belchen tunnel only in sections where the tunnel intersects the transition zone
from leached to unleached Gypsum Keuper was water inflow observed. In these areas
heaving of the tunnel and damages of the internal lining took place (Schillinger 1970).
Where the distance of the tunnel to the anhydrite surface was sufficiently large, the rock
mass was found to be dry and no damages occurred.
As in case of the Belchen tunnel, in construction lots 12 (underground turning loop) and 13
(Hasenberg tunnel) of the urban railway Stuttgart (Grüter & Liening 1976, Wittke & Rißler
1976, Wittke 1978, Wittke & Pierau 1979, Grüter & Wittke 1981) and of the Freudenstein
tunnel of the high-speed railway line Mannheim-Stuttgart (Klonsdorf & Schaser 1991) ac-
cess of water was observed only in the transition zones from leached to unleached Gypsum
Keuper. Where the distance of the tunnel to the anhydrite surface was sufficiently large,
these tunnels could be excavated in dry condition and no damages occurred.
23.3
Urban Railway Tunnel in Stuttgart, Construction Lot 12
23.3.1 Project
The approx. 1600 m long tunnel of construction lot 12 of the urban railway Stuttgart
(Figs. 23.14 and 23.15) belongs to the underground connection between the main
train station of Stuttgart and the airport on the Filder plain. With a radius of 190 m,
it forms an underground loop west of Schwabstraße station, which serves as a revers-
er for half of the trains coming from the main station.
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