Civil Engineering Reference
In-Depth Information
the cutting wheel - had to be filled with concrete. After cutting away the con-
crete between the pressure wall and the cutting wheel a lovely working
space would be created. A good idea, which still required optimization how-
ever: after the repairs of the main bearing seal, it would take a lot of time to
cut the stuck cutting wheel out of the concrete. A brilliant and simultane-
ously a very workable 'simple' solution for the problem was discovered in
the application of a foil seal with which the entire cutting wheel was covered
on the excavation front.
Divers spanned the foil, which was provided with feed-throughs, over the
cutting wheel. Through the openings, the space between the cutting wheel
and the soil was then filled with 'lean' concrete. Simultaneously - in order to
prevent that the foil would collapse or would come inside - soft mortar
which had the same density as the lean concrete, was poured on the other
side of the cutting wheel. After the concrete on the excavation front end had
hardened sufficiently, the soft mortar between the pressure wall and cutting
wheel was sprayed away. The result was a lovely clean working chamber
which could be used by everyone under atmospheric pressure.
The actual repairs to the main bearing seal - a task which as such was far
less exceptional than the creation of the circumstances which were neces-
sary for the implementation - took five days. The boring could then be
resumed . . . a world first!
Fig. 11.25
Exposed chambers of
the main bearing seal
during the repair work
Search WWH ::
Custom Search