×
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

Max. Equivalent Fluid Density

Max. Equivalent Fluid Density

Max. Equivalent Fluid Density

(OP)
I am looking for the maximum equivalent fluid density of soil used in the design of poured concrete retaining walls (see Reward Wall Systems).  The borings encountered SC overlying CL with N-values from 7 to 19.  Is there any similarity between the equivalent fluid density and equivalent fluid pressure?  Thanks for your input.

RE: Max. Equivalent Fluid Density

Equivalent Fluid Density and Equivalent Fluid Pressure are, I think, synonymous.  The highest I've encountered are about 80 or 90 lb/cf.  These seem pretty high for the soils you have described.  For those, with a level backfill you probably have about 45 or 50 lb/cf EFD. You should, of course, calculate the Rankine or Coulomb Active earth pressure coefficient which will lead you to the correct EFD to use.

RE: Max. Equivalent Fluid Density

The equivalent fluid density concept comes from the old code of practice CP2.  Usually, this is taken as 5 kN/m2

RE: Max. Equivalent Fluid Density

Because the equivalent fluid density or equivalent fluid pressure is another form to present the lateral earth pressure, it can vary according to the wall movement and groundwater conditions. For example, if it is a rigid wall, I will probably calculate the equivalent fluid density based on the at-rest earth pressure instead of the active earth pressure. If the retained soil is below the water table, the water pressure should probably be accounted for. If there is fill behind the wall, the earth pressure from the fill instead of the native soil should be used to get a quivalent fluid density.....

RE: Max. Equivalent Fluid Density

Hi RWF7437,

     I printed this thread out back when it was new.  I am about to send some info to a mining engineer in Canada about max pressures.  In that thread, which he started, some engineers expressed the opinion that pressures never even get up to full hydrostatic.  I disagree and so does at least  one of my reference books.  I plan to fax a copy of this thread to him too but I was wondering ,were those 80 to 90 pcf equivalents you mentioned measured or calculated.  I have calculated equivalent hydrostatics as high as 81 pcf.  I am looking for as much info to back up the higher pressures as possible, especially if it was gained by some kind of actual field testing.  Also I am interested in finding out what kind of tests could be conducted say near the face of a retaining wall or bulkhead.  

Thanks,
DPA

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