Civil Engineering Reference
In-Depth Information
the main bearing but it also prevented an influx of slurry or another material
coming from the working chamber getting into the main bearing. In princi-
ple, the next two chambers - filled with oil - fulfilled the same function. The
chamber next to the oil chambers, the so-called leakage chamber, was
empty. As samples could be taken from all the chambers, any material
found in this chamber was a major indication that the seal was not working
properly.
The main bearing seal was adjustable in the axial direction in the event that
grooves indicating wear and tear arose which required repairing. An important
condition for carrying out repairs was that this had to be done under atmos-
pheric conditions.
Aspects of the TBM design related to diving activities
The design of tunnel boring machines had to take into account repairs and
maintenance activities to be carried out by divers in the high pressure part
of the boring machine. Divers are therefore intensively involved in the design
of TBMs at a very early stage.
In order to make diving work possible, it was first necessary to make provi-
sions in the form of air locks to bring the divers under pressure and to give
them access to the part of the machine under pressure. In addition, special
(saturation) diving techniques had to be used for working at great depths,
in which the divers remain under pressure for a longer time.This meant that
special accommodation was required for them: a pressure cabin outside the
tunnel which was fitted out for a stay of 28 days at a pressure of 4 bar. The
divers then had to travel by train in a transport unit - the pressure
shuttle - to the TBM, where the shuttle was coupled to one of the air locks.
This was of great importance for the design of the tunnel boring machines:
the whole 'train' behind the shield of the TBM - the trailers and platform
carriages - as well as the logistical system had to take into account the possible
comings and goings of the shuttle.
Fig. 10.7
The pressure shuttle
for the transportation
of divers situated
under the platform
carriages of the TBM
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