×
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

Horizontal Directional Drilling (HDD) caused distress?

Horizontal Directional Drilling (HDD) caused distress?

Horizontal Directional Drilling (HDD) caused distress?

(OP)
A utility subcontractor was installing a casing under an existing building using HDD and drilling mud. As soon as "breakthrough" was achieved, the occupants of the building noticed a loud popping sound.  Some of the interior sheetrock walls cracked (slightly) and there appeared a noticeable (on one wall only) stair stepped crack in the brick veneer wall.  The crack was wider at the top (near the frieze board) than at the bottom.  The crack exists not only at the mortar joints, but in some cases through the brick itself. Some interior rolling files would not roll as easily.  This happened approximately one week ago, and the building seems to have "settled" down.  The rolling files stay put now and doors close tighter.  The conduit is approximately 3-4 feet below the building and is 10" diameter.  The building is of concrete slab on grade construction with a turned down edge beam.  My question is could the pressure induced from this drilling operation have caused a "lift-up" of the exterior edge beam?  By all appearances this is what happened.

RE: Horizontal Directional Drilling (HDD) caused distress?

Some questions/ramblings:
What is HDD?  Is the process fully sleeved to prevent the pressure from escaping?  What pressure is the HDD and drilling mud injected at?  Can the sleeved area be inspected by cutting out a portion of SOG?  Was there an existing condition report undertaken?  Were the cracks reviewed to confirm that they are recent?  Often cracking has been around for several decades, before people realize something is cracked.

If there was a leakage of HDD and drilling mud and even a small pressure 5 psi is equivalent to 700 psf... and can cause some real issues.  If the system is closed, it's a matter of determining if leakage has allowed HDD and mud to lift the grade beam.  Was there a void underneath the grade beam.

Dik

RE: Horizontal Directional Drilling (HDD) caused distress?

(OP)
dik,
You asked some of the same questions that I had asked the prime contractor.  HDD also known as horizontal directional drilling involves the advancement of a casing behind rotary cutting heads and drilling mud.  There are no sleeves involved.  The electrical contractor told me that he had seen asphalt pavement "rise" and then settle down in similar parking lot work.  I do not know the pressures involved and there were no "existing" condition reports available.  This major veneer crack was simultaneous with the punching through of the cuting head on the opposing side.  I hope that I have answered the majority of your questions, and I do not know if there was a void underneath the grade beam or not.  Thank you for your time.

RE: Horizontal Directional Drilling (HDD) caused distress?

In short, yes the HDD could have raised the building.  It could also lead to settlement of the building in time.  Placing a 10" HDD only 3 to 4 feet below a slab on grade building...generally sounds like a bad idea to me.

I would say that the contractor has some interior remolding to do.

RE: Horizontal Directional Drilling (HDD) caused distress?

(OP)
Guys,
Thanks for the replies.  This work is part of an expansion project for this building.  The brick veneer wall that cracked was coming out anyway.  When we excavate for the new grade beam for the addition, we can investigate this matter more in depth.

RE: Horizontal Directional Drilling (HDD) caused distress?

Was the foundation beam 4' deep and did he cut through the bottom of it?

Dik

RE: Horizontal Directional Drilling (HDD) caused distress?

(OP)
Dik,
The foundation edge beam bottom is approximately 2' below the floor slab, and I have been corrected that the conduits are approximately 6' below the floor slab.

RE: Horizontal Directional Drilling (HDD) caused distress?

I think it will have to wait until you get a chance to look at the areas damaged... you can possible tell which areas may have been uplifted... any idea of the pressure?

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