Franki pile

The Franki pile is a driven, cast-in-situ concrete displacement pile with an enlarged base in dry concrete and a cylindrical shaft.

Construction sequence

1. Positioning of the tube and construction of a water-tight gravel plug at the bottom of the casing preventing soil and/or water from entering it.

2. Bottom driving on the plug using an internal hammer. This operation causes the casing to compress the soil strata by lateral displacement.

3. Expulsion of the plug at the installation depth of the pile and insertion of dry concrete for the formation of the cast-in-situ (over)expanded base.

4. Lowering of the reinforcement before continuing the concreting phase

5. Concreting of the shaft

6. Withdrawal and recovery of the driving tube.

Fields of application

• Optimal geotechnical behaviour

• Designed to safely withstand very high tensile and compressive forces

• To reduce the part of the pile to be cut off, the execution of non-concreted lengths is possible

• Industrial projects and infrastructural works.

Environmental impact

• No soil removal (soil displacement pile)

• Limited vibrations since driving is done with an internal free-fall hammer

• Limited noise pollution since driving is performed with an internal free-fall hammer

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

Technical specifications

• Sectional area of the base up to twice the sectional area of the shaft; even more in case of an overexpanded base

• Pile shaft diameter of 457 mm up to 609 mm

• The pile shaft is filled with dry concrete (moist or wet earth consistency) or with slump concrete.

• Inclined piles with a maximum inclination up to 1/3

• Maximum allowable bearing capacity of 2.275 kN

• Driving inside the tube using an internal hammer (free fall hammer or ‘dameur’).