Retaining wall#Sheet piling

A sheet pile wall is a shoring to secure excavation or terrain jumps, can take over a sealing function at the same time. In some cases, sheet piles are built only for the seal against water or for the immobilization of pollutants by enclosing of contaminated soil. Usually made ​​of mild steel sheet piles are manufactured.

Manufacture and operation

A sheet pile wall consists of individual profiles ( bung boards or sheet piles called ), the most in the ground shaking ( vibrating ), are rammed or pressed. These special machinery come with Mäklern used, to which the corresponding rams, joggers, or pressing can be grown. With these machines, it is also possible to extract sheet piles for reuse from the ground.

The boards consist mostly of steel, can also be made of reinforced concrete, plastic or wood, in exceptional cases, however. The individual planks are joined together by interlocking locks ( tongue and groove ), so that a continuous wall is formed. When installing each board is led by the castle of the last rammed hall and positively connected with her. A completely water -tight connection is achieved with either inserted into the locks plastic seals or by subsequent welding.

Materials

For steel sheet piling the usual structural steels according to EN 10025 are used:

• S 235 JRC ( 1.0120 )
• S 275 JRC ( 1.0128 )
• S 355 JRC ( 1.0551 )

A special corrosion protection is not explicitly provided. It is assumed of approximately 0.03 mm / year, an annual erosion rate in air and soil of about 0.01 mm / year and in freshwater and seawater. Exact values ​​for the design are described in DIN EN 1993-5, Section 4.4 set.

Profiles

Sheet piling sections differ in shape and material thickness. Best known are lightweight sections ( Hoesch, Krupp ), panel profiles ( Hoesch Larssen, Krupp ), Z - profiles ( Krupp, Hoesch, Peine, Arbed ) and I-sections ( Arbed or Peine - box pile walls ). Related to the sheet piles are piles. However, they have no interlocking, thick lock and are therefore not suitable for sealing tasks.

The standard profiles are available in lengths of 6 m to 30 m.

Statics

In the simplest case, a sheet pile wall is held only by a correspondingly deep involvement in the underground, which corresponds to the static system of a cantilever beam. It must be considered that the sheet piling must be considerably longer than the depth of excavation. From a certain height of the wall, additional support is usually required. This is done by internal horizontal straps that gives additional supports the system. The straps are either against each other or tied back into the soil with ground anchors. It is also possible to support the straps by oblique struts on the bottom of the pit. Here, however, a relatively large amount (often non-existent ) is taking up space.

Areas of application

Main area of ​​application is the backup of excavations in areas where space does not permit embankment, or a seal against pressurized water is required ( see foundation (construction), construction waterproofing # seal for pressurized water). Here sheet piles are used as temporary safety measures that are taken after completion of construction and backfilling of the excavation.

Sheet piling of steel can be produced virtually waterproof. It is possible to work in a space enclosed by sheet piling, excavation ( sheet pile wall box) under the water table. On the downside, the pit is sealed by either a naturally dense soil or a concrete slab ( underwater concrete slab ). It is also possible with a water drainage to lower the groundwater in the excavation temporarily.

Sheet pile walls are used in addition to the time-limited use as shoring and permanently as components in hydraulic engineering for quay walls, flood walls, canals ( watercourse with artificially made water bed), piers and docks, and flood protection.

Sheet pile walls are among the "soft retaining wall '(' soft ' means: Depending on the depth down anchors or bracing must periodically be introduced, see also # pit excavation pit ). They are not suitable when subsidence above the excavation could lead to damage, such as in urban areas.

Combined wall

A special design for sheet piling walls are combined. To increase the stiffness of the retaining wall, I-sections are introduced as a bearing piles in the ground and filled in the spaces with conventional sheet piles at regular intervals. The bearing piles reduce by their high resistance torque, the deformations of the combined wall.

The bearing piles are similar in dimensions to the usual in construction I-beams, the edges of the flanges, however, are adjusted accordingly in order to produce a tight lock conjunction with the intermediate piles can.

History

The Romans used sheet piles. By the end of the 19th century, however, there were only wooden sheet piling. The steel sheet piling in today's execution was invented around 1900 by the Bremen State builder Tryggve Larssen. The wall consisted of a U- rolled section with a riveted connection terminal, the castle. They were manufactured at the steel mill in Dortmund Union from 1902, and as they proved to be successful, Larssen received a patent in 1904. 1902, the first sheet pile was driven into the ground as a waterfront structure in Hohentorshafen in Bremen, where it still stands today. In the period 1914-1921 the sheet piling section was developed with lock and since then rolled from one piece. In competition with the U- profile invented Baudirektor Lamp 1902, the Z- profile, which was first established in Luxembourg, in 1926 in a modified form at Hoesch Dortmund.