Applications and Techniques

This technique is now well developed and proven in the foundation industry. The piles are drilled and concreted in a single continuous operation allowing a much faster completion than for other pile techniques. A reinforcement cage is then placed in the fresh concrete further strengthening the piles resistance.

 

There are many different “sub-techniques” or company specific names for slight variations on the hollow auger technique, often defined by the type of drill bit or if the auger or part thereof may be left in the drill hole. The type of pressure in which the concrete is pumped may also vary depending on which of those sub techniques is applied, but in general hollow auger piles require relatively lowish concrete pressures, but are installed quicker and more efficient when using a crawler-mounted concrete pump which can run alongside the drill rig from drill hole to drill hole and provides powerful outputs to speed up the process. Hollow Auger Piles allow transferring loads to stronger soil layers for all types of build projects or civil engineering such as roads, bridges or underpasses. They are also used to produce pile walls either intersecting or disjoint to support build projects and secure excavations. Hollow Auger Piles can also be installed to prevent landslides, create flood protections or even protect existing buildings and structures.

IMPLEMENTATION

Hollow Auger or CFA piles are made by screwing a continuous hollow core bit into the substrate. When the design depth is reached, the auger is lifted upwards while the concrete is fed under pressure out of the bottom of the core pipe. A reinforcement cage is usually introduced into the still fresh concrete, with or without the use of a vibrator. The length of the CFA piles and their reinforcement will be adapted to the needs of the project. They can be reinforced along their entire length. CFA piles can exceed 30m in length and range in diameter.

 

BENEFITS

• Suitable for a wide variety of foundation projects.

• A cost-effective foundations solution, capable of carrying high compressive, pull-out and lateral loads.

• Can be installed in most soils such as sands, clays, silts, gravel and soft rocks.

• Hollow auger piles can reach pile depths of more than 30m and diameters of well over 1000mm.

• Their installation is very fast compared to standard bored piles.

• Low noise emission and no vibration make them ideal for projects in built-up areas with poor soil conditions and high water table levels.