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HomeTypes of pilingCFA - Continuous Flight Auger bored piling

CFA Continuous Flight Auger Piling

In addition to our range of driven steel piling techniques VolkerGround Engineering also provides in situ concrete bored piling, utilising the Continuous Flight Auger (CFA) technique.

CFA piling has become the most widely used bored piling system in the market. VolkerGround Engineering can design and install piles varying in diameter, from 450mm to 1200mm, and working loads, ranging from 1400k N to 10,000 k N, to a depth of 30m. Rigs used for this type of work are fully instrumented and provide electronic records of all piles constructed. VolkerGround Engineering presently operate PVE 55 DR purpose built CFA piling rigs.

The construction process used in CFA piling involves the rig drilling a hollow stem auger down to the required depth. Once attained, the auger is slightly withdrawn to enable an end cap to be blown free, by pressure within the concrete line attached to the head of the auger. Concrete is then pumped from a static pump and storage agitator.

Utilising the on board instrumentation system, the rig operator is able to match the tool withdrawal to the rate of pumping; ensuring positive pressure is maintained throughout the construction process. Once the full bore has been concreted and excess spoil removed a pre-formed steel reinforcement cage is inserted to the designed depth. You can watch the process in the below video.

Whilst CFA piling has become the most widely used bored piling system in the market certain ground conditions can lead to issues such as “flighting” – where saturated loose material is drawn into the pile bore, or “polishing” – when limited penetration is achieved in weak rocks and auger rotation smoothens the surrounding ground, with a loss of load capacity on the completed shaft.

Our industry experienced team of designers and estimators are able to provide guidance on ground suitability for all foundation requirements.

Where ground conditions or environmental constraints mean that driven steel sheet piles cannot be used to provide a retaining wall solution; VolkerGround Engineering is able to design and construct concrete bored pile walls utilising high torque Continuous Flight Auger plant. Alternatively, a combination of steel retaining wall and concrete bearing piles may be more economically advantageous for a particular development.

Whatever your requirement our team can advise on the best solution – steel driven, concrete bored, or a combination of the two within one specialist.