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


Cracking to Bearing Pile due to Heave - Statement in Design Report

Cracking to Bearing Pile due to Heave - Statement in Design Report

Cracking to Bearing Pile due to Heave - Statement in Design Report

I am reviewing a design report and came across the statement below. I am not sure what to make of it.

The development comprises a 6m deep basement, 450 and 600mm dia contig pile wall. Ground conditions comprise 2.5m of gravel then Clay. It is over consolidated clay so due to the stress relief there will be heave. The internal columns, walls are supported on pile caps.

As the bearing piles are in a basement, there will be a degree of basement heave. Hence, there will be a degree of pile cracking, which usually closes up as the building load is applied

How will the pile crack? due to the shaft friction and vertical heave causing a horizontal type crack? Is it acceptable to say it will crack and then close up. Can the reinforcement not be spec'd to minimise the crack width? Interested to hear peoples thoughts.


RE: Cracking to Bearing Pile due to Heave - Statement in Design Report

Sounds like they are saying heave (basement uplift) will result in axial tension on the piles.
If that is the case, the piles should be designed for the tensile force to prevent "cracking".
It does not sound like this is acceptable cracking. This is not normal shrinkage / temp. cracking.
It sounds like they are talking about actual structural tensile failure of the pile. If the basement
is "pushed" back down by loading, that does not fix a structural failure. Will there be any de-loading and
What kind of piles are these (reinforced concrete?)

RE: Cracking to Bearing Pile due to Heave - Statement in Design Report

Similar to what I used to see in south Texas with expansive clays - the drilled piers we used (with belled bottoms) would have additional vertical reinforcement used in response to anticipated levels of tension forces in each pier due to clays swelling upward.

The geotech reports usually provided a formula for the tension steel but as I recall, it usually ended up in the range of 0.75% to 1.0% of the gross pier area.

The reinforcement doesn't prevent cracking - only minimizes the crack widths.

Once loads are applied to the piers (piling) you counter the soil-induced tension with axial compression and the cracking is reversed as much as it can be due to possible material infiltration into the cracks.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

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!


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