Cased CFA Piling

Cased CFA is a modified version of traditional CFA and combines the benefits of both rotary bored and CFA piling using a temporary segmental casing.

The combined technique can achieve better pile installation tolerances in terms of vertically and plan position with enhanced surface appearance.

What is Cased CFA piling used for?

The cased CFA system is particularly suited to contiguous and secant retaining walls as the temporary casing helps to improve vertical tolerances. The lead casing and auger are fitted with tungsten tipped cutting teeth providing superior cutting power to keep the pile vertical and the ability to cut into female piles to achieve watertight retaining secant walls.

Key capabilities:

Rig loadings: 93.4 tonnes
Pile diameter: 600 – 750mm
Maximum depth: 22.5m
Up to 4,400kN

What are the advantages of Cased CFA Piling?

Quicker than traditional rotary bored piling methods
A relatively quiet and low vibration piling technique
Modern, hi-tech rigs including sophisticated onboard computers providing improved quality controls and records
Improved vertical and plan tolerances
Capable of drilling through man-made obstructions such as reinforced concrete
Reduced concrete over break and wastage
Limits flighting in poor soils
Improved appearance of finished retaining wall

Common Uses

Structural foundations across all construction sectors
Suitable for clay, weak rock and water-bearing sand, gravel, and glacial till
Secant and contiguous piled retaining walls and can be used in conjunction with temporary props and permanent anchors
Slope stabilisation and retention to prevent slip and landslides
Retention for deep excavations and basements close to adjacent structures
Ability to achieve tight drilling tolerances adjacent to site boundaries
Working next to buildings and homes and in environmentally sensitive areas
Used across infrastructure projects including tunnelling, road or bridge construction and flood prevention

Cased CFA piles are formed by drilling a hollow stemmed auger encased with a string of segmental casing of similar length into the ground to design depth. The drilling system includes twin rotary drive units that turn in opposite directions independently allowing pile arisings to exit at the head of the casing while simultaneously installing the casing. Pile arisings then fall through a full-length telescopic chute to ground level.

On reaching founding level, high slump or flow concrete is pumped through the hollow stem auger in a controlled manner ensuring a static head while the auger and casing is extracted simultaneously. Pile arising continue to exit at the head of the casing. The pile reinforcing cage is then inserted into the concrete.

Throughout the installation process sophisticated onboard computers monitor both the boring and concreting process. The cloud based online data portal allows engineering teams to monitor their contracts and individual pile installation from remote locations in real time.