×
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

Drilled Pier Spacing
3

Drilled Pier Spacing

Drilled Pier Spacing

(OP)
Does anyone have a recommendation on drilled pier spacing? I've read in a foundations book from college, "3 diameters center to center". Does this make sense for belled piers also?

RE: Drilled Pier Spacing

I agree with your 3 diameter spacing (minimum). The spacing has more to do with how the soils carry the load than the pile / drilled pier type. Put the piles / drilled piers too close together and you tend to overload the soils (whether they are point bearing or skin friction supported).

www.SlideRuleEra.net reading

RE: Drilled Pier Spacing

Belled piers use end bearing.  Spacing generally determined by bell dia.

Dik

RE: Drilled Pier Spacing

It depends on soil conditions, generally.  I've seen recommendations for 3 diameters clear, sometimes 3 diameters center to center, even some that allowed piers to be adjacent to one another.  The spacing recommendations should be in the same geotech report that gave you the pier recommendations in the first place, but absent that info, 3 diameters is a pretty good rule of thumb.  It also applies to belled piers.  Use 3 times the larger diameter.

RE: Drilled Pier Spacing

There are two issues.

1)  Make sure they aren't close enough together that you get interconnection of concrete between the drilled shafts.  This is especially important when constructing nearby drilled shafts on the same day.

2)  If drilled shafts are too close together, then group effects come into play and the group tends to act as a single foundation.

In the first case, we normally recommend a minimum of 4 diameter from edge to edge.  In the second case, it depends on the number of piers in the group and the soil conditions.

To answer your question, the diameter would be the belled diameter.

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