Slurry wall

A diaphragm wall is a protective wall in-situ concrete or sealing material that is partially manufactured in a bottom slot which is backed up before collapsing by a supporting liquid. The diaphragm wall is in use as pit support of deep excavations or deep foundations. A special form, it serves to landfill sites or opencast mines as a sealing wall.

The slurry wall was carried out fundamental research on the supporting function of bentonite suspensions developed in the 1930s by Christian Veder and brought in the 1950s with an Italian construction company to fruition. A diaphragm wall, which was initially built as excavation safety can - as well as the pile wall - later part of the building to be constructed, eg, as basement wall or underground garage wall.

Create the slot

For the construction of the diaphragm wall, a slot in the ground first with a diaphragm wall grab or a trench cutter excavated. For the stabilization of the slot supporting liquid is filled (usually a bentonite, a mixture of bentonite and water ) into the slot. If the slot wall to seal against ground water, the slot is guided into a water blocking layer of soil, such as clay. On both sides of the later slot baffles are created that lead the diaphragm wall grab and secure the top about 1 to 2 meters of slot area.

Ortbetonschlitzwand

After excavating the full slot depth a reinforcement cage is at Ortbetonschlitzwänden introduced and the supporting liquid replaced by concrete or steel fiber concrete. To this end, a tube ( Kontraktorrohr ) is lowered to just before the bottom of the slot, whereby the concrete goes directly to the bottom of the slot. Rising from the bottom up concrete displaces the supporting liquid, which is pumped out, degritted a regeneration plant and prepared for further use. Usual Diaphragm wall thicknesses are between 50 and 120 centimeters.

In tunneling and construction work slatwall also be used as side walls for the so-called top-down method.

A variant of the slit wall, the drainage wall, which can be simultaneously used for the removal of ground water.

Cut-off wall

At a Einphasenschlitzwand, which is also known as a sealing wall of the supporting liquid, a binder is added (typically cement), so that the supporting liquid hardens without exchange. One application for this type of construction is a subsequently created landfill liner.

To be able to perform the function of a Baugrubenverbaus be set in sealing walls before the stiffening of the cement - bentonite suspension and sheet piles for future support and Dichtungslemente or suspended.

Use in lignite mining

Diaphragm walls are also used in brown coal mining in Lusatia. To unlock the coal seams in 50 m to 70 m depth, a lowering of ground water to this depth is necessary. By pumping out a far-reaching groundwater funnel would form - as a parable with an average anticipated slope of 1/10. As a protective measure to be deep diaphragm walls applied to 90 m as a cut-off walls, so that the lowering of ground water is limited, and thus subsidence damage to buildings and to reduce adverse effects on waters around the open pits 70 m. In the area of the diaphragm wall creates a groundwater jump. An example of the protection of the groundwater level by diaphragm walls is the east side of the open pit Jaenschwalde. This open pit is located directly on the border with Poland. Since a lowering of ground water had to be restricted to the territory of the Federal Republic, here is a diaphragm wall was necessary.