Cased auger pile

A cased auger pile is formed using the twin rotary-drive system (also called ‘FoW’ or Front of Wall system), with extraction of soil under a temporary casing. The system is particularly suitable for the manufacturing of a pile wall (secant pile wall, tangent pile wall, contiguous independent piles). The execution is vibration-free and with limited noise pollution. The reinforcement is placed after the concreting phase.

Construction chart

Construction sequence

1. Positioning of the auger housed inside a steel drill casing. The auger and the casing are mounted on two independent, superimposed rotary heads rotating in opposite directions.

2. Auger and casing are simultaneously screwed into the soil, but rotate in opposite directions. Closing of the sealing flap fixed at the bottom of the auger prevents any infiltration of water and/or soil into the hollow, central axis of the auger during the screwing-in phase.

3. Lowering of auger and casing to the designed depth. The soil which is loosened at the auger tip is conveyed to the surface by the auger flights inside of the casing.

4. Discharge of the excavated soil through openings located at the top of the casing, underneath the rotary drive.

Opening of the closing flap. Pouring of concrete through the hollow stem of the auger as auger and casing are simultaneously withdrawn and formation of the pile shaft.

5. Placement of the reinforcement cage in the freshly concreted pile

6. Finished cased auger pile

Possibility of continuous registration of the installation parameters in order to monitor the quality of the execution process.

Fields of application

• Particularly used for the realization of soil retaining and/or water retaining walls (see secant pile wall)

• Can be executed throughout existing, old foundations (masonry)

• Can be installed close to existing facades (e.g. a few centimetres)

Environmental impact

• In vibration sensitive areas: the pile is formed without vibration or shocks

• In a noise-sensitive environment: low noise level generated

• Removal of soil

• A stable, dry and flat work platform is required.

Technical specifications

• Available diameters from 430 up to 830 mm

• The use of a temporary casing allows the realisation of cased auger piles directly in front of existing walls of adjacent buildings (15 cm).

The term FoW, which stands for “Front Of Wall”, is therefore used (VDW = "Vor Der Wand" in German).

• Allowable bearing capacity up to 2.350 kN.

Related projects for this technique

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