CONTINUOUS FLIGHT AUGER (CFA) PILES
This piling system is fast and economical. It has no vibration and limited noise levels. However, it does have some limiting features.
- High production levels are attainable in suitable soil conditions
- The system is economical in suitable soil profiles
- Noise levels are low and limited to the engine noise of the piling rigs
- There is no vibration associated with CFA piles
- In sandy soils below the water-table there is a reduction in soil strength in the immediate vicinity of the pile due to the drilling operation. As a result of this, the load / deflection performance of a CFA pile is inferior to that of a driven pile
- Soil falling off the flight can contaminate the concrete / grout of the pile shaft
- CFA piles have to be cast to ground level. This results in waste of concrete and excess trimming if there are deep cut-off levels
- There is very limited indication of soil strength during the drilling operation
The maximum depth of CFA piles is 30 metres at present and the recommended maximum rake 1:10.