Retaining wall
A retaining wall (with the appropriate construction, retaining wall ) is a structure that serves to secure incision and embankment slopes . Support walls therefore often run along roads and waterways . Within settlements as well as in the mountains, a stable slope is often not possible for reasons of space .
If the supporting wall is higher than 2.0 m, the stability must be proven by a static calculation. The wall is mainly loaded horizontally by the earth pressure of the slope.
Various methods are used to improve stability:
- the slope of the wall so that the weight of the wall counteracts the earth pressure
- widening the wall or increasing its own weight, see heavyweight wall
- the anchoring of the wall in a sufficiently heavy foundation or the use of corresponding precast concrete parts, see angled retaining wall
- if the wall is curved or angled, the use of the geometry by means of a shear and bending-resistant design of the crown area, for example in the manner of a ring anchor
- the stiffening of the wall with ribs on the front or back
- a back anchoring in the ground by ground anchors , strand anchors , rod anchors , drainage Anchor &. a., see anchor (geotechnical engineering) .
Support structures can also be constructed as reinforced earthen bodies. For this purpose, the stability of the ground is achieved by means of geogrids or steel strips, so that constructions with a slope of up to 85 ° can be carried out. However, the steeper variants from 60 ° have their own outer skin system in the form of z. B. blocks or gabions .
If the wall is not thick enough to prevent frost from occurring on the side facing the soil, it is essential to provide drainage to dehumidify the soil. The expansion pressure of the accumulation of water that freezes behind the wall would otherwise move the wall a little each winter, which over the years can endanger its stability. The bending stresses that occur in the process usually lead to cracks, through which seeping rainwater can partially run off. Depending on the soil conditions, it may be sufficient to remove the seepage water by drilling a sufficient number of holes in the wall. Alternatively, when building a heavyweight wall, filling the butt joints can be dispensed with.
The pressure of freezing water must be taken into account, especially in the case of soil backfills from a thickness of about 10 cm made of water- permeable material, if there is cohesive soil underneath that allows seepage water to run off slowly. Without adequate drainage, rainwater and meltwater can collect over an impermeable layer like a tub and cause the top of the wall to move several centimeters every year.
Types
There are different types of retaining walls:
- Bored pile wall
- Lining wall
- Heavy weight wall (often incorrectly also: heavy weight wall), e.g. B. Gravity dam
- Krainerwand
- Plastic-Reinforced Earth (KBE)
- Backpack wall
- Retaining wall
- Dry stone wall
- Angled retaining wall and walls made of L-bricks ("wall panels")
Retaining wall with slate facing in the Hamburg Botanical Garden
Support wall of the former Herford small railway on the Werre
Back-anchored sheet pile wall as a retaining wall
Overcut bored pile wall as a retaining wall at the approach to the Waldschlößchenbrücke in Dresden
Web links
Individual evidence
- ↑ Karl-Eugen Kurrer : A study of earth pressure on retaining walls . In: History of structural engineering. In search of balance . 2nd, greatly expanded edition. Ernst & Sohn , Berlin 2016, ISBN 978-3-433-03134-6 , pp. 52-58 .
- ↑ Example: After the new building of the swimming pool at the Schwanseebad in Weimar , a reinforced concrete retaining wall over three meters high, which was erected towards the higher street, inclined so much within a few years that it was completely demolished and rebuilt.