Timber piling questions. 1

[DrHurthing]

Thanks in advance.

I'm in my last year of mechanical engineering at Virginia Tech, so this is not my direct area of study.

My family and I began a small residential pile driving company. I've been studying up on the pile driveing and what we do is really simple. However, everybody seems to argue which way is the "proper" way to drive a timber piling.

Around here, people say to drive the big side down (butt is big side right?). This is for better bearing capacity in soft bottoms and so the ice doesn't pull the pile up when the tide changes. Others say put the skinny side down (tip?).

Most of the places we drive piles have soft bottom and we never hit rock. However, some places are hard sand with some river rock. One customer has pilings that fell over because the previous contractor only got them in 4 feet (looks like he was starting to split the top of the piling). I want to do the job right.

We have a hydraulic hammer that was made by some backyard guy, but it is used by several people (marinepiledrivers.com). I figure my two options are to either bore a hole or put a metal tip on the bottom of the pile. I'm rigging up a post hole digger from a bobcat as we speak and hopefully that will work.

As far as metal tips, I found that they make pointed ones that require cutting a point in the pile and flat round ones that just slip over bottom of the pile. In what instances is each one used and what are the advantages and disadvantages?

Lastly...pile or piling hahaha.

Thanks,
Jay

PS GO HOKIES!

 

[WSRIIIPE]

Drive small end down. In this manner the pile wedges into the ground generating skin friction. Big end down will degrade skin friction.

 

[DrHurthing]

Is there any suggested reading on the pile driving that addresses timber pilings in addition to other styles?

 

[WSRIIIPE]

Most PE review texts have a pile section as well as books such as "Foundation Analysis and Design". However, these are all on the design side. You may want to search the web for tips from the major manufacturers.

 

[SlideRuleEra]

Free downloads:
"Timber Pile Design & Construction Manual"

http://www.wwpinstitute.org/pdffiles/TimberPileManual.pdf

"Design & Construction of Driven Pile Foundations, Vol 1 & 2"

http://www.fhwa.dot.gov/engineering/geotech/library_arc.cfm?pub_number=42

Check out the website "Pile Driving Contractor's Association"

http://www.piledrivers.org/

...and check out this page (and others) at my website

http://www.slideruleera.net/AWPI-Page.html

http://www.SlideRuleEra.net

 

[BigH]

SRE has the right stuff on his web site!

 

[IFRs]

You really need a geotech analysis of the soils to determine the diameter and driving depth for proper bearing, friction and support. Just arbitrarily pounding toothpicks into the ground would not be my choice for my house or business.

 

[DrHurthing]

SRE, thank you very much for the links. I know what I will be doing for the next few days once it's to dark to work outside.

IFR, I agree for the need of a geotech analysis in your mentioned cases. However, we are driving piles only for residential docks. Most of these docks are no more than 3 feet wide. This does not mean I can just jam toothpicks into the ground (even though all the contractors around here have no engineering backround). However, the load the piles must bear is really low (compared to house foundations, of course).

My greatest concern is not that the piles will sink, but rather that the ice will pop them out. I'm learning from you guys but please don't think that I'm trying to put on a geotech hat.

 

[oldestguy]

Hi:

Another book is good, if you can find it. It is the "grandfather of all pile books" in my opinion. "Pile Foundations" by Robert D. Chellis. McGraw hill Book co. 1951.

He may not show all the latest pile drivers, but the basics are good.

Ice is a mighty strong puller. If your client can afford it, bubbler systems, or similar will do the job. Keeps the ice from freezing there. UW Madison Engineering Extension Dept has professors who specialize in this subject, cold areas marinas.