Construction pit walls

Construction pit walls secure construction pits against collapsing, soil slippage, water penetration and erosion. In this way, they protect existing buildings, roads, pipelines, working areas and people from disruption and danger.

Our specialists install construction pits according to the individual construction task. The choice of shoring depends largely on the prevailing geological conditions such as strata sequences, groundwater levels, local site conditions and planning constraints.

Depending on these conditions, we produce construction pit walls as flexible or low-deformation shoring systems and using separate casting and/or capped construction methods.

We offer the following shoring options:

• Diaphragm walls
• Cut-off wall with inserted load-bearing elements
• Bored pile walls
• Soil mixing method
• Sheet-pile walls
• Soldier pile walls
• Grouted walls
• Jet grouting walls
• Jetcrete walls
• Soil nailing
   

If necessary, we can also add support systems and base seals to construction pit walls using

• Anchors
• Reinforcements
• Injection floor slabs
• Jet grouting floor slabs
• Underwater concrete floor slabs
   

• Diaphragm walls offer a high level of security because they are extremely resistant to deformation and can thus absorb high loads from adjacent structures.
• The special joint profiles and low proportion of joints mean that diaphragm walls are technically watertight.
• As a foundation element (barrette), they can support very high concentrated loads.
• The construction period is shorter than that of bored pile walls, which saves time and money.
• Thin walls and flat surfaces create more usable space and increase economic efficiency.
• They can be constructed underground without disturbing the ground cover and without temporary anchors. This means that the project does not depend on the owners of neighbouring properties granting permission and reduces encroachment on public space.
• As a permanent structure in accordance with ÖNORM, they eliminate the need for a separate outer wall and thus save further costs.
• Desanding equipment is used to clean the support fluid (bentonite suspension), which means it can be used several times. This saves on resources.
• Energy diaphragm walls for geothermal use make the process even more environmentally friendly.
• The method enjoys a high degree of acceptance among local residents because it is low in noise and vibration-free.
• They can be installed under restricted working heights, e.g. under bridges.
   

Standards and regulations

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.

Production

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.

Energy diaphragm walls

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of execution standard DIN EN 1538
• Verification of the position, torsion and verticality of the diaphragm lamella with modern measuring technology such as inclinometers
• Clear processes governed by our quality management system in accordance with DIN EN 9001:2015

The following variants are available:

• Retaining wall and temporary construction pit system made of concrete or reinforced concrete
• Foundation element (barrette) for very high loads
• Energy diaphragm wall for geothermal use

• Cut-off walls provide a high degree of security due to their excellent sealing qualities.
• When combined with load-bearing elements and anchoring, this method is exceedingly low in deformation.
• Cut-off walls are an economical shoring solution that allows for a separation between structural and sealing functions.
• Huge depths of 20m to 40m are possible using the grab method.
• The construction period is shorter than that of bored pile walls, saving time and money.
• Level surfaces have several advantages for formwork and ensure economic efficiency.
• This method enjoys a high degree of acceptance among local residents because it is low-noise and vibration-free.
• It can also be executed under restricted heights (e.g. under bridges).

Standards and rules

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.

Production

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of execution standard DIN EN 1538
• Verification of the position, torsion and verticality of the diaphragm lamella with modern measuring technology such as inclinometers
• Clear processes governed by our quality management system in accordance with DIN EN 9001:201
   

The following variants are available:

• Cut-off wall with sheet-pile wall
• Cut-off wall with prefabricated concrete elements
• Cut-off wall with HEB profiles
• Cut-off wall without load-bearing elements,  for sealing purposes only

• Production does not generate vibrations and is therefore highly suitable for inner-city areas and near sensitive buildings.
• This tried-and-tested method has a high degree of reliability in execution.
• Bored pile walls are very low in deformation. The high rigidity of the walls enables construction pits to be created safely.
• They can be constructed as waterproof secant bored pile walls, for example for trough construction pits.
• They can also be designed as a permanent structure without a separate outer wall. Vertical loads can also be safely transferred into the load-bearing subsoil.
• Bored pile walls can also be used when building in existing structures where space is limited.
• Bored piles can be used flexibly as shoring walls or foundation elements.
   

Standards and regulations

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

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of DIN EN 1536
• Inclinometer measurements to check for deformation
• Clear processes governed by our quality management system in accordance with DIN EN 9001:2015
   

There are three types of bored pile walls, depending on how the piles are arranged:  

Secant bored pile walls

These are made using the back-step method. Unreinforced primary piles are constructed at a distance of slightly less than one pile diameter. The reinforced secondary piles are then produced to intersect with the primary piles, thus creating a waterproof shoring wall.

Tangent bored pile walls

In this variant, each pile is installed flush to the adjacent pile. The piles are produced one by one and reinforced. Tangent bored pile walls are not impermeable to water without additional measures.

Contiguous bored pile walls

The reinforced bored piles are constructed at a distance of more than one pile diameter. The remaining gap is usually sealed with jetcrete or jet-grouted sealing columns.

• Soil mixing walls provide a high degree of security due to their excellent sealing qualities.
• This method has exceedingly low in deformation when combined with load-bearing elements and anchoring.
• Soil mixing walls are a cost-effective shoring solution. The surrounding soil is utilised in- situ, rather than extracted. Minimising soil extraction cuts down on transport and disposal costs, especially for contaminated soils.
• The soil mixing method is environmentally friendly and has a low carbon footprint as it uses comparatively little cement.
• The method can be applied flexibly and adapted to a wide range of soil properties and other requirements.
• Shorter construction periods compared to bored pile walls save on costs and time
• Even surfaces yield a number of advantages for formwork and ensure economic efficiency.
• The method enjoys a high degree of acceptance among local residents because it is low-noise and vibration-free.
• Comparatively little space is required for the construction site facilities.
   

Standards and rules

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).

Production

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of the execution standard DIN EN 14 679
• A manufacturing record prepared for each pair of columns
• Clear processes governed by our quality management system in accordance with DIN EN 9001:2015

Soil mixing is available in the following design variants:

• Soil mixing wall as a cut-off wall
• Soil mixing wall with load-bearing elements as a temporary construction pit system
• Individual soil mixing columns for subsoil improvement

• Sheet pile walls provide a high degree of safety due to their excellent sealing qualities.
• There are a variety of profiles available. This allows the sheet piling to be flexibly adapted to the specific requirements of the construction site.
• The method is low on resource consumption, as the profiles can be extracted and reused.
• Low-impact installation methods mean that sheet piling can also be used in inner-city areas. Hydraulic jacks and state-of-the-art high-frequency vibrators are used for this purpose.
• Sheet pile wall production is resource-friendly, no soil needs to be extracted.
• The site facilities require very little space, and the execution does not depend on weather conditions.
   

Standards and regulations

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).

Production

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of DIN 1054 and the recommendations of the “Construction Pits” Working Group
• eDtailed manufacturing logs
• Clear processes via our quality management system in accordance with DIN EN 9001:2015
• Regular oscillation readings
• Lock detectors that ensure that the individual piles are connected by interlocking joints (tongue and groove).
   

The following variants are available:

• Free-standing sheet pile wall
• Sheet-pile wall with chording and anchoring / bracing

• One of the main advantages of soldier pile shoring is its excellent ability to adapt to local conditions. It is relatively easy to cut out recesses for pipes, etc.
• It is produced quietly and without vibrations and is therefore acceptable to local residents.
• Shoring can be constructed very close to existing buildings.
• New buildings can be constructed immediately adjacent to Berlin shoring without leaving additional working space.
• The shoring soldiers and the upper infill are usually withdrawn and reused. The soldiers are processed and placed in interim storage. Berlin shoring is thus both resource-friendly and sustainable.
   

Standards and regulations

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).

Production

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.

We ensure high execution quality with:

• Individually coordinated instructions
• Compliance with the requirements of DIN EN 1997-1
• Inclinometer measurements to check for deformation
• Clear processes via our quality management system in accordance with DIN EN 9001:2015
   

There are several different types of soldier pile shoring:

Berlin shoring

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

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

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.