Pressure tunnel

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View into the pressure tunnel of the Amsteg I power plant during construction in 1921.

A pressure tunnel (also called pressure shaft in the vertical direction ) is a tunnel, i.e. an underground tunnel that is used as a water pipe , whereby the entire cross section of the tunnel is filled with water, so that a corresponding hydrostatic water pressure builds up ( pressure pipe ).

This is the difference between a pressure tunnel and a gravity tunnel , which is not completely filled and in which the water flows off freely following the gradient, like in an open channel .

Pressure tunnels are mainly used to guide the headwaters of storage power plants , more rarely in water distribution systems to guide drinking or irrigation water, in sewer systems ( pressure drainage ) or to discharge water that penetrates in mining or tunnel construction ( water solution tunnels ). The first pressure tunnels are already known from antiquity (underground aqueducts ); later pressure tunnels were used in various water arts .

Pressure tunnels are created using tunneling and mining methods (see mining tunnels ).

So that the water under the high pressure does not seep through pores and cracks in the wall rock, the tunnel is not washed out by the current and no rocks can loosen from the wall that could damage the pumps and turbines, pressure tunnels are usually watertight in modern times Lined with pressure-proof ("armored") , for example with reinforced concrete , high-strength plastic or a sheet metal wall . Only if the rock is very dense or if the losses due to seepage are insignificant in relation to the effort involved, a waterproofing can exceptionally be dispensed with.

To avoid pressure surges long pressure tunnel have today usually a moated castle .

literature

  • Gerhard Seeber and R. Friedrich: Pressure tunnels and pressure shafts . Spektrum Akademischer Verlag, 2001, ISBN 3827412846 , ISBN 978-3827412843
  • Jürgen Giesecke and Emil Mosonyi: Hydroelectric power plants. Planning, construction and operation . 5th edition, Springer Verlag, Berlin, 2009, ISBN 978-3-540-88988-5
  • Anton Schleiss: Underground hydropower plants . In specialist journal: Wasser Energie Luft - Eau Energie Air 79 (1987), No. 9, pp. 217-218, ISSN  0377-905X