Base expander for timber pile

[IFRs]

I would like to increase the load capacity of to be driven timber piles. Is there a manufacturer of a pile base that would increase the diameter of the pile from 7" to 9"?

 

[SlideRuleEra]

To increase point bearing capacity, I don't think so. Pile tips such as these

http://www.piletips.com/timber.html

are used to help penetrate hard soils (Arrowhead type) or to keep the wood from "brooming" (Boot type) when the pile is driven to hard rock.

One answer, of course, would be to specify larger piles. A specification for piles usually calls out the tip diameter, diameter 3 feet from the butt, length (often in 5 foot increments), and (if needed) preservative treatment type & quantity (pounds per cubic foot, retention).

An expensive "trick" would be to specify piles longer that needed, then cut off the small diameter end before driving.

A more cost effective "trick", if the soils are right (soft) AND your Geotech Engineer approves, is to drive the piles upside-down (butt down - tip up). Not often done, but will work under the proper conditions - got to have point bearing, though. The reverse taper is great for resisting uplift but not worth 2 cents for providing any skin friction capacity for "down" loading. May also have to look at the pile as an essentially unsupported column, subject to buckling under load.

http://www.SlideRuleEra.net

 

[BigH]

One other way is to get your extra load capacity with a few more timber piles - they are not that expensive compared to other types.

 

[Floodwall]

A 15,000 ft-lb hammer would split an upside down pile in most cases unless predrilled, which contractors hate to do. I would specify a class B timber pile and add piles as necessary to meet the load requirements.

I'm driving Class 0.8 CCA treated timber piles (L=40') now at a site in Norco, Louisiana and the actual tips are on the order of 9 to 12 inches. Butts are up to 18" diameter and need to be trimmed to fit in hood of hammer. (Southern Pine Piles). For your info on a job that has about 1000 piles add about $550 for each additional pile.

 

[IFRs]

What is the difference between class A and B piles?