We have seen many ingenious ways to extract old concrete foundation piles.

·   We have seen the ICE TP clamp for extracting square and round piles with a limited diameter [see ”selected furher reading" on the right]. This is for extracting piles with good strength/ integrity that can withstand the distributed total 120t-180t clamping force without being crushed.

·   We have seen casings that are driven around piles, with a lifting mechanism inside the casing, to extract the old pile by lifting out the pile together with the casing. The combined weight is considerable and leaves a large hole that needs to be filled up.

·   We have seen clients drive No. 6 sheet piles fitted with water jetting pipes along old piles and then lifting them out together, with mixed efficiency.

And then recently we stumbled upon how Dutch company BAM does it. BAM has developed a tool that uses high frequency vibrations from an RF vibratory hammer, combined with water and air jetting, for exceptional results even for weakened cast-in-situ piles. The water and air loosen the soil eliminating the friction, and the simultaneous vibration eliminates the last remaining downward pull on the old foundation pile. Because the vibro is clamping a welded side plate it can drive deeper around te pile, and the pile can be extracted while the vibro continues vibrating the outer casing. Shanghai ICE has just added a diesel-powered water jetting system to our rental fleet that is a perfect addition for this application.

The photos in this article were taken at Amsterdam Schiphol Airport. BAM was tasked to remove hundreds of old concrete piles so that excavation work for the basement of a new terminal building can be started. The piles were 40 years old cast-in-situ concrete piles. These piles were not reinforced with steel rebar so that care had to be taken not to break the piles during the extraction process. An extractor casing tool designed for this job overcame this challenge.

Short explanation of the work method:

Locate the old foundation pile; drive a short large diameter casing around it to protect the surrounding area using water jetting to create over pressure; drive the ‘pile extractor casing” around the old foundation pile and 3 meter deeper than the pile you want to remove; blast air and water around the pile to loosen the soil from the pile; vibrate the hammer and start pulling the pile out with the cranes auxiliary hook.

Step-by-step work instructions:

1.  A short oversized 1420mm diameter support casing is driven around the foundation pile to enclose the working area, and to be able to visualize the inclination of the pile

2. The topsoil is excavated so the pile tip emerges. An operator measures the distance from the casing rim to the pile tip.

3.  For extracting 15m long piles, an 18m long 800mm diameter extractor tool was prepared for this job, the extractor pipe is fitted with injectors for water and air and has three lifting fingers. The extractor casing tool is filled with water for downward pressure.

4.  The extractor casing is driven by an ICE high frequency vibratory hammer 3 meters deeper than the old foundation pile. The last five meters of soil layer is a dense sand layer. The hammers RPM should exceed 2000 for best result.

5.  Water and air jetting are started. The soil and water are pushed out at the top of the extractor casing.

6.  The pile, covered with clay in some places, is now free of soil friction, and is lifted out of the extractor casing. The clay layer that formed a watertight soil layer should now be repaired with a clay plug.

7.   The back-fill level is measured, in this case it is 9.3 meters. Swelling clay pellet material is prepared to plug the hole and reinstitute the water tightness of the ground. Clay is added until the desired depth is reached, then sand is used as back fill.

An alternative method is to lift the extractor casing tool together with the pile. This can be done by fitting the tool with lifting fingers:

The lifting fingers are moved in position by air pressure. They will carry the weight of the pile out of the soil

Why does this application work best with an ICE RF hammer?

The extractor casing is heavy and needs more eccentric force than casings used for other purposes, the high frequency hammer allows for better soil liquefaction. Old foundations removal projects are generally in urban areas where resonance free operation is preferred as they avoid resonance damage. For this reason, BAM chose the 36RF powered with an ICE 1000 power pack to drive the “pile extractor casing”. For extracting piles that are over 20m long we would recommend a 50RF resonance free hammer.

Equipment required:

Extractor casing:  we recommend a wall thickness greater than 20mm, the side clamp plate should have a similar thickness and be sufficiently large to allow the clamp jaw to grab it and have certified weld quality.

Water jetting: pressure 8 kg

Air compressor:  200L capacity

Crane size:  for 20m casings we recommend a crane over 80t

For more information please contact our team. We are on standby to answer your questions about pile design and water jetting.

About BAM 

BAM Infra is the number one partner for infrastructural connections in the Netherlands. We offer innovative solutions and we do this in our own, distinctive manner. Solutions that are just a bit different. Just a bit smarter. And always safe and sustainable. That is what we stand for. That is our goal. https://www.baminfra.nl/about-us