×
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

Gravel/sand pressure?

Gravel/sand pressure?

Gravel/sand pressure?

(OP)
The simplest way to present this question is to assume the following:
Typical formwork.....6in wide by 7ft tall and filled with gravel.
What is the design pressure from the gravel?.....thanks in advance for your response.

RE: Gravel/sand pressure?

35 degrees is a common estimate of the angle of repose for gravel. With that in hand, perhaps you can treat it like you would a retaining wall?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Gravel/sand pressure?

I don't have the books handy, but bin pressures would be one way to go here. Using something like a Rankine earth pressure is not correct.

RE: Gravel/sand pressure?

For dry gravel, you can assume an equivalent liquid pressure of 24 to 26 lb / ft^2. Smaller gravel has less voids therefore the higher value. These numbers are based on traditional Rankine / Coulomb assumptions and should be conservative values. See pages 5 and 8 of "US Steel Sheet Piling Design Extracts" on this page of my website:
http://www.slideruleera.net/Steel-Piling.html

www.SlideRuleEra.net idea
www.VacuumTubeEra.net r2d2

RE: Gravel/sand pressure?

I would approach this with Bin Theory. If you have Gaylords structural engineering handbook it can walk you through it. Other references are ACI 313-97 which addresses design and construction of concrete silos and stacking tubes. These all follow Jannsen theory. The hard part is going to be assuming a wall friction angle for the material against the wood, but I would probably assume something along the lines of what it would do against concrete and look at a range of numbers. With that small of a gap, the material is going to be significantly carried by vertical wall friction, so the forms will carry a lot of the vertical load.

RE: Gravel/sand pressure?

IRC uses 30 psf/ft for basement walls backfilled with gravel.

RE: Gravel/sand pressure?

(OP)
thanks to everyone for their responses......because of the narrow width, it was questionable wheather the Rankine/Coulomb or the bin theory would apply....

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