DPA screw piles - Vroom Foundation Technology
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DPA screw piles

A DPA (Drilling Push Aside) pile is a cast-in-situ displacement pile system. No soil that might be polluted will rise to the surface. The production of this foundation pile type is vibration-free and that is of importance in the case of production near adjacent structures that might be damaged by subsidence and/or vibrations.

Vroom Funderingstechnieken (Vroom Foundation Technology) has gained wide experience with DPA piles and gives advice about the application options of this pile type and other screw pile systems. 

Special features of DPA screw piles

The pile system works on the principle of soil displacement, so only a small portion of the soil into which the pile is drilled will rise to the surface. DPA pile installation is vibration-free, so the piles are especially useful where there is a danger that adjacent property may be damaged by subsidence and/or vibrations. The installation process is low-noise, causing fewer problems in the immediate vicinity; it is suitable for use in residential areas, near schools and public buildings, etc.

Uses for DPA screw piles

  • Particularly useful in house-building, non-residential building and other new-build construction where noise and pollutants are potential issues.
  • Suitable for urban renovation projects in which vibration is a concern in terms of adjacent structures or buildings. 
  • Displace soil and are thus suitable in polluted sites, where soil reaching the surface would have to be removed and sent for remediation.
  • Are an alternative to non-displacing screw piles where they bring up contaminated soil that seriously contaminates the building pit, or where the contaminated soil brought to the surface cannot or may not be disposed of.
  • Generate less noise pollution than ‘conventional’ pile driving systems, and are thus suitable for use when extending existing buildings that are already in use.
  • Can be used for soil conditions or loads requiring a long reinforcement cage that can be fitted centrally to the pile with the required coverage.

DPA

  • The pile head is driven and cast up to working level and can be finished at the appropriate height above working level. Pile length can be directly adjusted depending on the soil conditions: the pile is always installed to the calculated level. Adjustments to the pile specifications are possible until just before the start of the project.
  • Maximum installation gradients: leaning backwards 5:1 and forwards 10:1. 
  • Can take compressive as well as tensile stresses.
  • No soil will rise to the surface.
  • Vibration-free pile system.
  • The entire length can be reinforced. Reinforcement can be applied in the shaft before concrete is poured.
  • Factors from load tests with an influence on load-bearing are evaluated and established by 'Bouw- en woningtoezicht' [Netherlands Building Control Committee]. Competitive compared to other displacement piles as a result of a higher load-bearing capacity and a 'clean' building pit.

Quality control 

Vroom Funderingstechnieken produces DPA piles to an implementation procedure designed for Vroom Funderingstechnieken in the context of internal quality control, nationally-recognised standards and conditions. 

Checking geotechnical load capacity

DPA piles are essentially installed to the calculated drilling depth. To do this, the drilling torque is measured to assess and identify the base.

Allow us to advise you

We at Vroom Funderingstechnieken prepare our leaflets and website with the greatest possible care and attention. However, no rights can be derived from such content. If you use information from our leaflets or our website without verification or further advice, this is at your own risk.

Vroom Funderingstechnieken accepts no liability for the correctness and/or suitability of the information for the purpose you envisage. Should you have any questions about the use of our products for actual projects we advise you to contact our sales department.

Technical specifications DPA screw piles

Production process

Realization schedule drilled DPA piles  

  1. The DPA drill is positioned with the hydraulic rotary drill attachment.
  2. The hydraulic rotary head turns clockwise through the strata in between.
  3. The hydraulic rotary head turns clockwise to the correct depth.
  4. The reinforcement cage is installed to match the required length.
  5. Wet concrete is then injected into the stem of the screw pile.
  6. Wet concrete is injected during the process up to at least 1m above working level. The tube is then retracted from the ground either still or slightly rotating clockwise.
  7. The pile can then be finished if necessary.

Reinforcement

B500B standard.
Pile reinforcement and dimensioning are based on information supplied by the designer. Spiral reinforcement mesh makes the reinforcement cage appreciably stronger, resulting in less deformation.

Before the concrete is poured, the shaft reinforcement is hung at the correct height in the drilled tube.

Extra reinforcement at the top, if required, is applied immediately after the pile is produced.

Bearing capacity

The pile classification factors have been established using test loads carried out by Geomet of Alphen aan den Rijn, the Netherlands, which have been positively evaluated by the Netherlands Building Control Committee.

Pile cap bearing capacity

αp = 0.8 (section III Koppejan NOT reduced) 

β = 1.0 The part of the screw pile that displaces the soil is driven (screwed) into the subsoil.

Borehole friction factor

αs = 0.010 (no reductions).
The part of the screw pile that displaces the soil is driven (screwed) into the subsoil. Tension: αt = 0.009.

Load and deformation behaviour

They show consolidation behaviour similar to that of driven piles within the serviceability limits.

Load spectrum

Compression up to 2500 kN max. Tension up to 400 kN max. Vroom Funderingstechnieken can give advice on the bearing capacity of a DPA pile in specific soil conditions.

Available pile diameters (mm)

310, 360, 410, 460 and 510.
The length of the pile depends on the nature of the substrate and forces to which the pile is exposed. Vroom Funderingstechnieken will assess feasible screw depth.

Concrete grades

Grades C20/25, C25/30, C30/37 and C35/45.

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Can we help you with your project?

Contact Rob Sman. Dial +31(0) 299 409 542 or send us an e-mail.

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