×
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

Retaining wall Pile embedment in rock

Retaining wall Pile embedment in rock

Retaining wall Pile embedment in rock

(OP)
Hi,

We are about to try to design a retaining wall for a 15+m height of weathered volcanic ash above a 'soft' sandstone. Does anyone know of any simple way to calculate the embedment depth required to achive a cantilever action? All we have is a dynamic probe blow count on the sandstone at the site and general lab data for the sandstone from the local viciinty

Gareth Williams
Geotechnical Engineer,
Auckland New Zealand

RE: Retaining wall Pile embedment in rock

Madziwa,

What type of structure are you envisioning to retain your weathered ash? It's not clear from your post.

I would imagine that analysis of a cantilevered wall (sheet, soldier, tangent, secant) would suffice for any of those types, although you will have to evaluate the lateral capacity of the pile-rock system using a p-y (LPILE, COM624P) or Brom's analysis.

See the COM624P User's Manual here (http://www.fhwa.dot.gov/engineering/geotech/library_listing.cfm) for some background. See also Reese and van Impe's recent book "Single Piles and Pile Groups under Lateral Loading".

For the retained height that you mention (15m), you may need to install tieback anchors or similar restraints to keep the embedment depth reasonable and reduce moments in the piles. Alternately, you might consider a MSE/RSS wall.

Jeff

RE: Retaining wall Pile embedment in rock

Here is a simple way, from a 1931 Carnegie-Illinois Steel Corporation Catalog:

Quote:

For walls entirely cantilever, the penetration below bottom should equal approximately the unsupported height above.
Since this would require 15+ meters of embedment for an entire steel sheet pile wall the modern techniques, suggested by jdonville are almost guaranteed to be cost effective.

www.SlideRuleEra.net idea

RE: Retaining wall Pile embedment in rock

(OP)
Thanks,
We plan on using a barrier pile wall (soldier pile). MSE/SRW walls probably won't work due to  limited extent available for geogrid length. Tie backs are under consideration, but again due to limited site width behind the wall, they may not be feasible.

Cheers

Gareth Williams
Geotechnical Engineer,
Auckland New Zealand

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