The cased CFA pile is a continuous pile drilling and installation technique with low noise level and no vibration. It is ideal for excavations requiring shoring systems abutting existing buildings within built-up areas with weak soil conditions and high levels of ground water.

Common uses

Provide earth retention, especially on site boundaries or close to adjacent buildings
Provide structural support
Prevent landslides or protect existing buildings (often combined with other techniques such as anchors or soil nails)
Infrastructure projects such as tunnelling, road, rail or bridge construction

Process

Cased CFA piles are constructed by rotating a hollow stem continuous flight auger within a temporary casing into the soil to a designated depth. The double rotary drive units for the auger and casing rotate in opposite directions, simultaneously drilling them into the ground. This allows for faster continuous drilling while the casing helps to keep the pile vertical, which is important for applications such as secant pile retaining walls. Concrete or grout is pumped through the hollow stem, maintaining static head pressure, to fill the pile drill hole as the auger and casing is slowly removed. Upon completion the reinforcing (pipe/I-beam/cage) is installed while the concrete/grout mix is fluid.

We have extensive experience of working on challenging sites where access is difficult or compromised, and where existing infrastructure such as underground services and transport links are present.

Advantages

Minimizes de migration and cave-in of surrounding soils
Very effective shoring system for excavations abutting other structures
Low noise level and minimal vibration so ideal in built-up areas with weak soil conditions and high levels of ground water
Resists compressive, uplift, and lateral loads
A cost-efficient foundation solution
Can be installed in most soil conditions such as sands, clays, silts, gravels and soft rock
Construction is quick as temporary support systems are not required
Higher construction tolerances and pile surface appearance when compared to traditional CFA

Quality assurance

Close control of the installation process is essential to ensure the highest quality pile construction.

All Keller CFA rigs are equipped with sensitive state-of-the-art instrumentation that monitors all aspects of CFA piling, including pile depth, auger rotation, penetration rate, concreting pressure, extraction rate and over-break. The instrumentation produces an individual quality control construction record for each pile that includes element identification, date, time and operator details.