Bored pile walls

Bored pile walls are used to stabilise construction pits and are particularly suitable for deep construction pits or in areas with adjacent structures. As overlapping bored pile walls, they also enable watertight construction pits and are suitable for both temporary and permanent applications such as construction pits, shaft structures, slope stabilisation and hydraulic engineering.

Lexikon: Bohrpfahlwand

Stable backup solution

Bored pile walls
Excavation shoring with structural and waterproofing functions

Bored pile walls are among the key elements of construction pit shoring. They are used in particular for deep construction pits or in areas with adjacent structures and utility lines that are sensitive to settlement. Bored pile walls are used in particular for construction pits with stringent requirements regarding deformation, as well as in areas with adjacent structures or utility lines that are sensitive to settlement.

As overlapping bored pile walls, they can also fulfil waterproofing functions within the excavation structure. Different design variants allow for adaptation to project-specific subsoil conditions and boundary constraints.

Bored pile walls can be used for both temporary and permanent applications. Areas of application include, amongst others, construction pits, shaft structures, slope stabilisation as well as hydraulic engineering structures. In hydraulic engineering, bored pile walls are used, for example, as drainage walls or as part of groundwater treatment measures.

Applications include:

Construction pit shoring
Shaft structures
Slope stabilisation
Hydraulic engineering

Bored pile walls are used in particular for construction pits with stringent requirements regarding deformation, construction pit depth or adjacent structures.

Bild einer Bohrpfahlwand; Zusätzlich wurde diese mit Verpressankern gesichert

Technical brochure
Construction pits

Construction pit walls (only available in German)

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Benefits / Features
bored pile walls

Installation: low-noise and low-vibration; also suitable for inner-city areas
Scope of application: suitable for a variety of subsoil conditions and project requirements
Deformation behaviour: shoring wall with minimal deformation
Waterproofing: can be constructed as overlapping bored pile walls to provide waterproofing against groundwater
Permanent structure: can be used without an additional external wall, depending on the project
Existing buildings: can also be used where space is limited
Multiple functions: can be used as both a retaining wall and a foundation element

Basic facts of bored pile walls

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

For greater excavation depths, the bored pile walls are back-anchored to reduce head deformation and pile diameter. The anchors can be installed either to remain permanently in the ground or to be removable, either partially or completely.
PORR offers a range of grouted anchor systems to meet various technical and economic project requirements. Through the use of anchors, girders or bracing, the bored pile walls are dimensioned in accordance with the respective project requirements. For particularly deep construction pits, the bored pile walls can be secured with multiple anchor layers.

Design variants
There are three types of bored pile walls:

Secant bored pile walls

Skizze einer ueberschnittenen Bohrpfahlwand — © PORR

The method involves the ‘pilgrim’s step’ technique. To achieve this, unreinforced primary piles are driven into the ground at a spacing slightly less than the pile diameter. The reinforced secondary piles are then driven, cutting into the primary piles. This creates a watertight retaining wall.

Tangent bored pile walls

Skizze einer tangierenden Bohrpfahlwand — © PORR

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

PORR Spezialtiefbau Bohrpfahlwand Aufgeloeste Bohrpfahlwand — © PORR

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.

Quality assurance

We ensure a high standard of workmanship through:

Individually coordinated procedural instructions
Compliance with the requirements of DIN EN 1536
Inclinometer measurements to monitor deformation
Clear processes via our quality management system in accordance with DIN EN 9001:2015