CFA
Continuous Flight Auger piling (CFA) is suitable for most construction projects. Causing minimum disturbance, CFA is ideal for noise and environmentally sensitive sites for both load bearing piles and excavation support.
Basic Technique
A hollow stemmed continuous flight auger is rotated into the ground to the required depth. As the auger is withdrawn, concrete is pumped down the hollow stem under balancing pressure forming a shaft of liquid concrete to ground level. A reinforcing cage is then inserted by hand or vibrator.
Two significant factors influence the load bearing capacity of CFA piles: the sophistication of the equipment used and the experience of the operators on the ground. These factors are often overlooked at design stage, and the depth of experience within BBGE engineering teams, plus its investment in R&D are both key strengths in this area.
Technique Enhancements (SIRIS)
Stent Integrated Rig Instrumentation System (SIRIS) consists of a computer and sensors on the piling rig, a notebook computer used by the site foreman and a database at head office, all linked via GSM.
The system provides instant data on parameters such as:
- Auger depth
- Auger rotation
- Concrete pressure
- Concrete volume
- Productivity
The data is analysed on site to produce graphical representations of pile conformity. Data is then stored centrally to provide historical reference. Key data is also available to project managers via SMS interrogation.
Strengths
- Minimal disturbance - hence limited risk of damage to adjacent structures
- No casing is required
- Suitable for all soil types
- Ideal for retaining walls
- Speed of installation
What is CFA used for?
- Noise and vibration sensitive sites
- Interbedded sequences of clays and sands
- Water bearing strata
- Piling in weak rocks
- A broad range of loading conditions
- Retaining walls
- Rapid installation
