Bored pile walls

Bored pile walls are one of the key elements of temporary construction pit systems. Their high rigidity and the associated low degree of deformation make them particularly suitable as a stiff, low-deformation shoring method. This method is primarily used in construction projects located close to existing buildings or buried pipelines that are susceptible to settlement.

Secant bored pile walls are used to create watertight trough construction pits. Multiple design variants allow for individual adaptation to a wide range of subsoil conditions and construction site requirements.

Bored pile walls can be used both for temporary and permanent applications. For example, secant bored pile walls are used as a water-blocking or watertight variant. Pile walls are also used in hydraulic engineering, for example. Here they are used as deep drainage walls or reactive walls for groundwater purification.

Applications include:

• Construction pit shoring
• Shaft structures
• Securing slopes

Bored pile walls are used wherever there are high requirements for limited deformation and other types of shoring are no longer viable due to the depth of the excavation or the loads from adjacent structures.

• 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.