Foundations

Displacement Piles

Bored Displacement piles are usually employed in brown field sites where the cost of removing spoil of site is expensive.  While the technique is relatively new to Ireland it is now widely considered to be an acceptable, and often attractive, alternative foundation solution. The piles are produced and cast in-situ with minimal creation of spoil using low noise and vibration techniques.

Bored displacement piles can be constructed to depths of up to 26m in a range of diameters. Piles can be designed to carry lateral and tension loads as well as bending moments.

Ground Conditions

The bored displacement piling technique is suited to a wide range of soil types, particularly very loose and loose to medium-dense granular materials (sands and gravels) and cohesive materials (clays and silts) which are very soft, soft, firm or even stiff. Piles can be constructed through alluvial deposits and man made fill. The absence of spoil from the operation makes this technique ideal for contaminated sites.

Basic Technique

A hollow stemmed specially designed displacement auger is rotated in to the ground displacing the soil laterally this avoids the need to deal with large volumes of spoil. As the auger is withdrawn, concrete is pumped down the hollow stem while the operator monitors the concrete pressure and flow rate forming a shaft of liquid concrete to ground level. A reinforcing cage is then inserted in to the wet concrete and pushed in by hand, attending excavator or vibrated in.

Advantages

The bored displacement pile is suited to a range of soil types and can improve the strength of the soil during its installation.
Minimal spoil production leads to reduced costs from haulage and disposal. Production can be fast because of the absence of spoil to clear from the head of the pile.  On contaminated sites the risk associated with handling spoil is eliminated.  The improvements to the soil lead to more efficient pile design and superior performance when compared to other pile types of bored pile.

 

 

 

 

Displacement Piles Pilot Street Belfast

 

Please click on the images above to download some case histories. For further case histories please go to our Projects page.