Removing existing timber piles 1

[abusementpark]

Let's say you have a job in which an existing building is being demolished to rebuild a new structure on the same footprint. However, there are existing timber piles placed in fairly uniform grid across the entire existing footprint.

Is there a good way to remove the piles and fill the holes to make the site suitable for new construction?

 

[Ron]

You can remove the piles by vibration and then re-compact the soil, assuming mostly granular soil, using vibrating probe (TerraProbe process). To do this, you use a 30 to 36 inch diameter open end pipe attached to vibratory hammer. Insert the probe on a grid basis. Does an excellent job in granular soil.

Used it for deep compaction of granular fill/dredge spoils for a large project in the Bahamas and for smaller projects in other locations.

 

[BAretired]

Record the exact position of each pile...then leave the piles in place or cut them off below surface. If possible, place new foundations in positions so as to avoid existing piles.

BA

 

[JedClampett]

Is there a reason you can't use the existing piles?

 

[msquared48]

If the pile are still good, they could be tested in place and rated.

Years ago we were installing a foundation for a new three story structure and ran across an old 18" clear grain timber pile inside one of our pilecap locations. It was still as good as the day it was driven and did not budge one iota when tested with the piledriver. We reconfigured the design locally and used the pile. No reason not to.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[SteelPE]

We are in the process of completing a project which involved the demolition of an existing structure on wood piles with a new structure to be placed on wooden piles. In this instance the locations of the piles was not in line with the new structural elements so testing for reuse was out of the question as there was no cost advantage for the testing.

We abandoned the existing piles and cut them off below the new cap elevations. In some instances, this cause some problems with placement of new piles where existing piles were in the way. In these cases, we had to quickly come up with a suitable location for the new pile as a pile driver was waiting for the information.

 

[chicopee]

Vibratory extractor mounted from a crane should do the job.

 

[IDS]

This occurred on the first site job I ever worked on (circa 1974).

We got them out with a crane and an excavator with a hydraulic hammer. The excavator hit the top of the pile (roughly vertically), while the crane heaved upwards. Took a long time, but we got there in the end.

If I recall correctly, the piles were about 50 years old, and still in excellent condition (other than the tops ).

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[abusementpark]

Finding a good way to use the existing piles will be difficult. Many of the tops were severely damaged during the demolition process. I'm not sure how far down you would have to cut on some of them to get a tip with some integrity. But the bigger issue is the difference in loading magnitude and distribution between the new and existing structure. As I said, the existing of piles are in a pretty tight uniform grid (approximately 6' o.c.). The new structure will have concentrated loading such that large pile caps will be required.

 

[TpaRAF]

In Florida we have a widget called a pile nibbler, that basically shears concete piling by crushing. The problem here would be excavating down enough to get the hydraulic shears into place.

Why couldn't you excavate down to the point a chain saw could be used to lop away the piling?

Two feet is the typical cutoff below grade, but that's more of a rule of thumb.

If you consider the soil to distribute along a 60° angle, the 'spread' at the surface would be equal to the depth. So ... 2ft below the surface for a 12in pile would give (2+1)²/4·pi area (~7ft²). 3ft depth, 4pi (~12.5ft²) area.

This would serve to reduce any "point support" issues caused by leaving the prior piles in place.

Backfilling any trenches or voids would be the same any other subsurface void -- compaction to meet your code standards after suitable soil or gravel backfill has been placed.

Good luck on your project.