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!

*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.

Jobs

Piles under horizontal load into bedrock

Piles under horizontal load into bedrock

(OP)
Guys,

I am involved in a free standing structure, essentially an upside down L whose base must resist low vertical loads, horizontal load and moment.  The team is heavily vested in mounting each of these onto a single caisson pile (drilled pier, filled with concrete), to an appropriate depth.

In a uniform cohesionless soil, the minimum calculated depth (controlled by deflection) is approx. 9m. (This is about equal to the structure's height above ground). However, the site has bedrock at around a 6m depth.

Is it common practice to neglect the soil in such a case, and design as a cantilever anchored into the bedrock, or are there more refined methods? (FEA with soil "springs" and a fixed base, etc.)

tg

RE: Piles under horizontal load into bedrock

Certainly you may profit from the presence of rock and -6 m, and of the presence of the soil above it, except if very weak. In my view, ordinary FEM packages may give structural approximation enough, and only when nonlinear behaviour in the soil is paramount the more complicated geotechnical FEM programs should be of necessary resource.

RE: Piles under horizontal load into bedrock

I wouldn't ignore the overburden soils.  They are there and provide real resistance to horizontal/moment loads.

RE: Piles under horizontal load into bedrock

I agree with dcarr, will be way too conservative to ignore the contribution of 6 m. of soil. Consider using a program like LPILE which will take into account the bedrock,overburden and caisson stiffness. The analysis will give you the deflection and bending moment in the caissons. You could also consider, going with caisson to bedrock and getting additional lateral resistance from increased diameter or a collar.

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


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close