Segment
As tubbing (plural: tubbing ., In Süddeutschl / Austria tubbing ) a component of the outer shell is a shaft or tunnel , respectively.
Tunneling
A modern segment is a prefabricated concrete segment for reinforcement in tunnel construction . In its most common form, seven segments form a complete ring. The tunnel is then composed of a large number of rings. Very high demands are placed on a segment in terms of accuracy of fit. The error tolerance is normally in the range from one to a few millimeters . The casting is therefore mostly done in metal formwork. Tubbings are manufactured with or without sealing tapes, depending on the geological requirements.
In modern tunnel construction, the segments are laid by the driving machine , which is also supported in the axial direction on the edges of the segments that have already been laid in order to achieve the advance.
In tunnel construction in the Alpine countries , stiffening with tubbing began to prevail about 100 years ago, when tunnels were being built under increasingly difficult geological conditions as a result of increasing traffic . In the last few decades their use has decreased somewhat due to the spread of the New Austrian Tunneling Method .
In order to enable a change of direction, the concrete segments are designed and manufactured in such a way that they are slightly beveled, i.e. a few centimeters wider on one side. When installing on straight stretches, the segments are then installed alternately offset by 180 °; this offset is then interrupted for curves. This ensures that segment rings can be produced evenly in series.
In preparation for the installation of cross-passages , special steel segments are placed in the appropriate position, which can easily be dismantled later.
Mining
Since mid-19th century, and later rolled tubbing were cast iron for waterproof expansion used by shafts. At least at that time, segment lining was the most expensive form of shaft lining. The process originated in England and was introduced in the Ruhr mining industry by William Thomas Mulvany , who ultimately developed the system into German tubbing .
Joint sealing
For sealing of tubbing segment joints sealing bands are used (for example, from neoprene ) or Pikotagen ; lead sheet strips were used for cast iron tubbings.
Individual evidence
- ^ Fritz Heise, Fr. Herbst, Carl Hellmut Fritzsche: Textbook of Mining Studies , 8. u. 9th revised edition, 2nd volume, Springer-Verlag, Berlin / Göttingen / Heidelberg, 1958, p. 170.
