×
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

How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

(OP)
Greetings, fellow Eng-Tippers.
Numerous authors suggest assume 10D for loose soils, 15D for medium soils, and 20D for stiff soils, for critical depth.
I am analyzing an existing 60-ft long pile that was driven thru sand, and am trying to determine the SKIN FRICTION capacity using empirical methods.
I plan to later verify the results via A-pile or other software.
For now, I am trying to understand the theory and its practical application.
The textbooks don't seem to cover realistic scenarios where the pile goes thru various soil stiffness properties.
What critical depth should one assume for a 60-ft long pile where the upper 20 feet goes thru loose soil, the middle 20 ft is medium soil, and the lower 20 ft is stiff soil?
Thank you.

RE: How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

FHWA Driven Piles Manual Vol I has some good information on static design. The better way to determine the capacity of an existing driven pile is to run a dynamic or static load test.

RE: How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

Looks like critical depth isn't really addressed anymore.

RE: How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

For pile capacity, I suggest using effective stress ("beta method") for all soil types for static loading conditions.
I suggest reading some Fellenius papers, which many are free to download. Search "unified design piled foundations Fellenius".
Critical depth is an inaccurate and flawed concept, but will usually result in a conservative pile depth calculation.

RE: How to Determine Critical Depth for Design of Pile Thru Mixed Soil Strata?

(OP)
I appreciate the fast replies. Thank you, all.

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! Already a Member? Login


Resources

White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. Download Now

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