Extracting piles can on occasion be a more difficult task than installing them. In the main, it is certainly as challenging a job and one best left to the specialist contractor.

The modern world continues to become less tolerant of noise pollution and far more concerned about the adverse effects of ground vibrations. It is increasingly unacceptable working practice to simply leave piles in the ground only to create problems for future generations. Indeed, there is a growing movement that argues piled foundations should be considered a recyclable part of any structure that uses them – they MUST be taken out.

The most common method of pile extraction is to utilise a pile vibrator gripping the top of a pile whilst pulling with the considerable force generated through the line pull of a crane. Usually this process is effective, but on occasion the forces generated at the pile top can be sufficient to either break off part of the pile top or simply lose grip. When this happens the result can be catastrophic with the vibrator and crane jib being catapulted over the back of the crane causing it to topple and collapse.

With pile extraction work often dictating the use of a large crane the whole process can be cumbersome and expensive. Given that piles are often extracted during the latter stages of construction when access or headroom may have become limited as a result of the surrounding new construction the challenges start to become apparent.

Add all these issues together and there is a clear need for alternate methods of pile extraction. Dawson believes it has developed a formidable alternative whilst at the same time addressing concerns over noise and vibration.

CONEXPO-CON/AGG 2005 will see Dawson’s X400 and X1000 metric tonne Universal Pile Extractor revealed for the first time in the USA. The machines utilise two hydraulic cylinders acting on a common jaw assembly to extract practically any steel pile. An on-board computerised system provides the operator with simple push button control of all independent functions and processes an automated extraction sequence.

Sheet piles (‘U’ or ‘Z’), H-piles or Pipe piles can be accommodated in the powerful jaw assembly utilising different insert arrangements.

In low headroom situations the pile can be extracted and cut-off in short lengths.