×
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

P-multipliers for piles in a retaining structure

P-multipliers for piles in a retaining structure

P-multipliers for piles in a retaining structure

(OP)
The structural engineer is proposing to reinforcing an existing slope with drilled shafts, which will be 24 inches diameter and 30 inches center-to-center. Basically, 6 inches room is left between shafts for installing tiebacks installed into the body of the retained structure.

What P-multipliers do we need to recommend, considering the spacing is only 1.25(=30/24) times of B?

Recommendations by AASHTO 2000 and US Army 1993 simply do not provide values for spacing below 3B, except uncertain extrapolation is used. Would 0.2 be reasonable? or even 0.1? Thanks.

RE: P-multipliers for piles in a retaining structure

Where to start...

As far as I'm aware, neither AASHTO or USACE provides recommendations for drilled shafts used to stabilize a landslide, so quit looking for a code solution.

There should be very little vertical load on the drilled shafts, only the vertical component of the tie-back load. So figure the vertical load that will be on the drilled shaft and then look at how the drilled shaft will shead that load. If it is in very small end bearing, figure the overlap in the pressure cones and see if you have an acceptable factor of safety. If the load path is to shead the load in friction, again figure the overlap and see if you are ok.

Other options include installing the tie-backs at a flatter angle so there is less of a vertical load component.

Mike Lambert

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