Tetrapod (structure)

Tetrapods (Greek τετρα, tetra = four, ποδές, podes = feet ) are concrete blocks, which are used in coastal structures. The "arms" of about six ton stones are aligned with the corners of an imaginary tetrahedron. Tetrapods are on the coastline, to dams or piers lined up or stacked in several rows. They serve primarily as a breakwater and to reduce the force of the water waves hitting against the shore.

History

The invention of tetrapods goes to the French laboratory Ets. Neyrpic back in Grenoble. As of 1950, the tetrapods have been patented in many countries for Neyrpic.

Production

The production of tetrapods is easy and is usually made ​​directly because of the cheaper transport of liquid concrete at the intended operating: A reusable mold made ​​of steel is poured from the top with seawater-resistant concrete. After it is cured, it is opened on the outer sides and the finished tetrapod being lifted by a crane to its final location. Used in port here are often floating cranes are used.

Applications

Also in river engineering tetrapods are used for bank stabilization. They have the advantage that many spaces occur as a safe haven for fish and other aquatic animals. They are useful also in the construction of harbor fortifications Leitdämmen or on a solid surface. The use of tetrapods on sand beach, as on the Hoernum - Odde, however, can lead to serious environmental damage. Said and nature reserve area shrank by over 60% since 1968.

Research Projects

The Alfred Wegener Institute (AWI ) launched a project in 2009 to explore the impact of the tetrapods along the German North Sea coast to the natural development of coastal structures. Particularly, the researchers want to find out how the tetrapods influence on salt marshes and tidal flats.

Military use as a roadblock

Tetrapods were also used as anti-tank obstacles. At the San Giacomo pass tetrapods were introduced into a stream bed that is armor- consistently in the dried or frozen state.