GROUND CONDITIONS
The CFA technique is appropriate for most ground conditions including soft rock, but becomes particularly economical in non-cohesive sands, gravels or silts where otherwise long casings or drilling fluids would be required.
PILE DETAILS
CFA piles are drilled to the required depth using a hollow stem continuous flight auger. High slump concrete is then pumped under pressure through the stem whilst the auger is withdrawn at a controlled rate.
As the spoil is removed a shaft of fluid concrete is formed up to ground level. The reinforcing cage is the introduced through the wet concrete.
INSTRUMENTATION
The CFA technique carried out by Simplex provides the highest standard of pile construction which is assisted by on-board computerised monitoring systems. A simple screen display within the driver’s cab shows the auger depth, speed of rotation and rate of penetration. During the concreting stage, diagrammatic presentation of pressures and volume ensures adequate supply along the pile length. All data is stored for subsequent review and can be printed out in an easily understood format to confirm pile integrity.
PLANT EMPLOYED
Simplex operate a large fleet of dedicated CFA rigs together with additional dual purpose hydraulic rigs. Diameters range from 300mm up to 1200mm and depth up to 30 metres can be achieved. LOW HEADROOM equipment is also available allowing work within 6.5 metres depending upon project requirements.
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