Civil Engineering Reference
In-Depth Information
Starting provisions
The boring process started from the southern access ramp in which the con-
crete external work (sections 1 through 4) acted as the starting shaft. To
make the start possible, the following facilities had to be applied during and
after the completion of the concrete work:
- a shield cradle for the assembly of the tunnel boring machine - one for
each machine;
- steel platforms for the assembly of the trailer carriages and platform
carriages.
In connection with the enormous length of the entire boring train - about
195 metres - this construction had to be assembled on the embankment.
- blind rings and casing rings in the northern end wall and an impermeable
block on the outside of it, in order to make the boring through this wall
possible. The impermeable block was carried out as a filling of sand-
cement mortar (B5) applied layer by layer, within the total filling-in of the
construction pit;
- a steel thrust framework. The framework is fitted in the floor and the roof
at the location of section 2;
- facilities for the anchoring of the blind rings.
Fig. 8.6
A section of the boring
machine (being
assembled) on the
shield cradle
Design and implementation of the northern
access ramp; caisson and construction pit
At the northern bank the minimum construction depth required for the first
section of the access ramp (the receiving shaft of the tunnel boring machines)
was approximately 18 metres
NAP. Given the circumstances, it was not eco-
nomical to build a concrete structure at this depth within an anchored sheet
pile pit with tension piles and underwater concrete. That is why the choice
was made for a pneumatic caisson to be immersed from the surface level.
After receiving the tunnel boring machine, the construction was provided
with a concrete internal work.
Search WWH ::
Custom Search