Cased Continuous Flight Auger (Cased CFA) piling combines the speed and low-vibration benefits of conventional CFA piling with the precision and stability provided by a temporary steel casing. Using a dual rotary drive system, the casing and auger rotate independently, enabling simultaneous drilling and casing installation for improved accuracy and ground support.
Installation
The technique is particularly suited to challenging ground conditions, high groundwater environments and projects requiring close proximity to existing structures. It is widely used for high-capacity foundations, contiguous pile walls and hard/hard secant walls where tight construction tolerances are essential.
Cased CFA piles are constructed using a hollow stem continuous flight auger housed within a temporary steel casing. A dual rotary drive system rotates the casing and auger in opposite directions, allowing the casing to advance while spoil is extracted efficiently through the auger flights.
Once the design depth has been achieved, concrete is pumped under pressure through the hollow stem as the auger is withdrawn in a continuous, computer-monitored operation. The temporary casing provides bore stability throughout installation before being extracted, after which the reinforcement cage is inserted to the required depth.
This controlled process delivers excellent verticality, reduced spoil generation and reliable pile construction, even through variable or difficult ground conditions.
Capability
Quinn Piling operates modern dual rotary piling rigs capable of delivering Cased CFA solutions across a wide range of commercial, residential and infrastructure projects throughout Ireland and
the UK.
Our Cased CFA capability includes:
- Load-bearing foundation piles
- Contiguous pile walls
- Hard/Soft secant pile walls
- Hard/Hard secant pile walls
- Close-proximity piling adjacent to existing structures
- Deep basement and retaining wall construction
- High groundwater and unstable ground conditions
Our specialist equipment enables the installation of high-quality piles in demanding ground conditions where conventional CFA piling may not be suitable.
Key Benefits
Cased CFA piling provides the speed of conventional CFA piling together with the enhanced accuracy and ground support of temporary casing.
Key benefits include:
- Low noise and minimal vibration
- Excellent bore stability in unstable ground
- Suitable for high groundwater conditions
- Improved verticality and construction tolerances
- Reduced risk of necking and overbreak
- Lower concrete consumption through reduced flighting
- Capable of drilling through difficult and mixed ground
conditions - Close-proximity piling adjacent to buildings and boundaries
- Fast installation with full electronic monitoring throughout
construction
Applications & Performance
Cased CFA piling is commonly specified where conventional CFA piling requires additional ground support or enhanced construction accuracy.
Typical applications include:
- Commercial and residential developments
- Basement excavations
- Contiguous and secant retaining walls
- High-rise developments
- Infrastructure projects
- Bridge foundations
- Water and wastewater treatment facilities
- Urban developments adjacent to existing buildings
- Sites with high groundwater or unstable soils
Quinn Piling can install Cased CFA piles in diameters ranging from 350 mm to 1000 mm, with pile depths of up to 25 metres, depending on ground conditions and project requirements.
The dual rotary system provides exceptional installation accuracy, enabling piling to be carried out within close proximity to existing structures while maintaining low noise and vibration levels.
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