Construction pit walls

Diaphragm walls are designed and manufactured in accordance with DIN EN 1538 and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises “Baugruben”, EAB). The stability of the opening is verified in accordance with DIN 4126.

The soil is excavated using the grab method to create a rectangular slot in the soil, while at the same time the pit is filled with support fluid (bentonite suspension). Excavation is carried out in sections using a cable excavator and diaphragm wall grab. Guide walls are built beforehand along the route the diaphragm wall will follow to guide the grab.

In subsequent work stages, the suspension is regenerated, the reinforcement and a stop-end element are installed to form the next element, and concrete is poured using the contractor method (from the bottom up). The individual elements are lined up next to each other and are connected with special joint profiles so as to form a wall that, according to structural findings, is technically watertight.

Generally speaking, diaphragm walls are between 0.45m and 2m thick, at depths typically ranging from 20m to 40m. In each case, these depend on the type of grab used. Diaphragm wall cutters can also be used for depths of 40m and more.

The reinforcement cages of the diaphragm walls can be fitted with PE pipes as circulation conduits. This allows the diaphragm wall to be thermally activated as a solid absorber in contact with the ground. Since many different factors can influence the economic efficiency of the energy diaphragm wall during planning and execution, the designer of the energy system and the execution team must work closely together.

Cut-off walls are designed and manufactured in accordance with DIN EN 1538 and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises “Baugrube”, EAB). Verification of the stability of the open diaphragm is carried out in accordance with DIN 4126.

Cut-off walls are produced along the same lines as diaphragm walls, using the grab method. Guide walls are built along the route where the cut-off wall will stand beforehand to guide the grab.

A cut-off wall compound is used to stabilise the earth walls. This does not have to be replaced in the single-phase system; instead, its high cement content means that it sets in place. Precast concrete elements, HEB profiles and sheet pile profiles are used as structural load-bearing elements.

Cut-off wall thicknesses typically range between 0.45m and 1.0m, with typical depths ranging from 15m to 40m.

Bored pile walls are calculated in accordance with DIN EN 1536 and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises “Baugrube”, EAB). Diameters typically range from 60cm to 150cm, with standard depths of 15m to 30m.

Production begins at ground level in the course of the shoring line by creating a concrete boring template. Cased or uncased boreholes, depending on the stability of the subsoil, are then driven into the ground using rotary drilling.

If groundwater is present, boring is carried out with hydrostatic force in order to prevent the groundwater pressure from causing a break in the ground.

Once the planned final depth has been reached, a reinforcement cage is inserted. The concrete is then poured using the contractor method. A concreting pipe is guided into the borehole up to the pile toe and the concrete is discharged from the bottom of the concreting pipe, forcing water and slurry upwards. This is continuously extracted and reused. Concreting is thus carried out from the bottom up. 

House connection lines can be realised later via a removable plug-in girder shoring without time-consuming mortising work. For this purpose, the concreting is not carried out up to the top edge of the ground and after concreting the plug-in beams are placed in the reinforced piles. The empty borehole is then backfilled with suitable material. The excavation is used to install the timber shoring, which can be removed once the shell has been completed and is no longer functional.

Anchored bored pile walls

At large excavation depths, the bored pile wall is anchored to reduce head deformations and pile diameters. The anchors for the anchored bored pile wall can be manufactured to remain permanently in the ground or to be removed, either partially or completely. As a leading supplier of grouted anchors, our company offers different anchor systems from a single source and can thus always provide the technically and economically optimal solution for the client’s construction project. Bored pile walls at large depths are economically dimensioned by using anchors, chording or bracing. If the construction pit is especially deep, the bored pile walls are secured with several layers of anchors.

Soil mixing walls are designed and manufactured in accordance with DIN EN 14 679 and the recommendations of the “Construction Pits” Working Group (Arbeitskreis “Baugruben”, EAB).

The surrounding soil is mixed with cement slurry or custom mix using a frame leaded, double mixing paddle, so that a pair of columns is formed every time the mixing tool is lowered and retracted. A series of these soil concrete columns is produced to create a continuous cut-off wall. HEB profiles or double U-beams are used as static load-bearing elements.

Column diameters typically range between 50cm and 80cm, with typical bore depths of up to 16m.

Sheet pile walls are designed and manufactured in accordance with DIN EN 1054 and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises "Baugruben", EAB).

The sheet piles are vibro-compacted into the ground with frame leaded high-frequency vibrators. A range of steel profiles are available for this purpose. The individual sheet piles are friction-locked together by interlocks and form a continuous wall. Sealing tapes, bitumen grouting and additional welding can be used to achieve a very high degree of watertightness.

If the neighbouring buildings are particularly vulnerable, sheet piles can also be gently inserted into the ground using hydraulic jacks. If there are no requirements for noise or vibrations, especially heavy profiles can be installed quickly and economically using the corresponding pile drivers.

From a certain excavation depth, the sheet pile wall must be secured to prevent severe deformation. This is done by installing chording on the side facing the construction pit, which is then tied back into the soil with grouted anchors. If anchors cannot be used, the chording can also be shored on the inside.

Soldier pile walls are designed and manufactured in accordance with DIN EN 1997-1, DIN 1054, and the recommendations of the “Construction Pits” Working Group (Empfehlungen des Arbeitskreises ”Baugrube, EAB).

The first step involves vibro-compacting the steel soldiers into the ground or inserting them into pre-drilled holes and concreting them in at the base. The soldiers are vertical steel girders (e.g. HEB girders, IPB girders or double U-profiles) placed at intervals of around 1m to 3m. The concrete grouting at the base increases the rigidity of the shoring and thus reduces deformations.

The second step is to excavate the soil step by step and to infill the exposed adjacent soil between the steel profile girders with timber (planks or squared timbers). The soil can also be infilled with jetcrete.

Anchored soldier pile walls

Berlin shoring systems at greater excavation depths must be anchored. The anchors for the anchored soldier pile wall can be manufactured to remain permanently in the ground or to be removed, either partially or completely.  As a leading supplier of pressure-grouted anchoring, our company offers different anchor systems from a single source and can thus always provide the technically and economically optimal solution for the client’s construction project. Soldier pile walls at great depths are economically dimensioned by using anchors, chording or bracing. If the construction pit is especially deep, the soldier pile walls are secured with several layers of anchoring.

Where there are high live loads, some sections are designed as bored pile walls. The bored pile wall can also be anchored.

Berlin shoring is the most common type. After the excavation has been completed, the wooden planks are placed between the IPB beams and held in place with wooden wedges. At greater excavation depths, a horizontal chording of U-profiles is placed in front of the shoring soldiers for support and secured with grouted anchors.

Hamburg shoring involves lining up wooden planks in front of the shoring soldiers and attaching them to the soldiers with hook plates. This variant is rarely used anymore.

Essen shoring uses two parallel U-profiles connected with lugs as shoring supports. The surrounding soil is infilled in the same way as with Berlin shoring. If the shoring is anchored, the pressure-grout anchors are drilled between the U-profiles, thus eliminating the need for chording. This saves space in the construction pit, which is then available for building construction.