×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Timber friction pile - top 6ft excavated

Timber friction pile - top 6ft excavated

Timber friction pile - top 6ft excavated

(OP)
I have been asked by a co-worker to find out if excavating around the top 6ft of a 45ft friction timber pile (to remove contaminated soil) would impact the capacity of the pile.  The piles currently are not supporting any load.  They were only driven and are awaiting pouring of pile caps.

The thought is to excavate the top 6ft, and backfill with crushed stone.  Intuitively, I would think this should not effect the capacity of the piles, with the thought that most of the strength of the pile is gained deeper down their length and the top 6ft or so is not a factor.

Thoughts?

RE: Timber friction pile - top 6ft excavated

I usually ignore the top 5 feet of the pile when I calculate capacity.  I would contact the geotech who provided the capacities and ask them their assumptions.

Off the cuff, I think it should be OK since you are putting good, compacted soil back in before applying load to the piles.

If the piles are laterally loaded (probably not with wood piles, but it happens) then you may have to take a different material into account.

RE: Timber friction pile - top 6ft excavated

I see no problems with this.

RE: Timber friction pile - top 6ft excavated

I guess the question I have is:  Why the excavation?

RE: Timber friction pile - top 6ft excavated

(OP)
In response to TDAA...

There is contaminated soil on site (or, there was) and it was supposedly cleaned up and then the piles were driven.  Another sample was taken after driving, and the contamination is just barealy (~5%) over the limit.  They are oging to test again, but if need be, they will need to take out the soil and replace with clean.

RE: Timber friction pile - top 6ft excavated

OK, thankn you.  At least you have a good reason to do the excavation.  I also belive this should be OK.

I would be cautios of creating a bathtub effect when backfilling withh the granular material, if you are removing cohesive materials.  I would recommend a below fill drain in that case.  

RE: Timber friction pile - top 6ft excavated

If these are new piles I agree there should not be a problem. Someone should look to check if capacities were field measured and what the actual vs. required is.
If these are existing timber piles, you may have a concern. exposing timber piles that have been submerged can start te piles to decay. Iftat is the case the piles must be consently wetted down.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources