×
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

Determination of pre-consolidation pressure by strain-energy method

Determination of pre-consolidation pressure by strain-energy method

Determination of pre-consolidation pressure by strain-energy method

(OP)
Hello,  
Our laboratory only uses typical Casagrande method for determination of pre-consolidation pressure in conventional consolidation tests.  I am planning to introduce a second option and currently my first choice is strain-energy method such as Tavenas method.  There are two questions here:
1 – Does anyone have a comment in regard to using strain-energy method for determining pre-consolidation pressure.  Most of the published papers are calling it a more accurate and easier to use method.  I am wondering if you have come to the same conclusion in real life experience/project?

2 – I have read a few published papers on this topic and there are a few methods for strain-energy which are slight different.  However, in order to use it in practice, I prefer to use a method that is endorsed by a standard.  I could not find anything in ASTM.  Is there any standard that endorsed this method?

Thanks in advance.
Regards,  geoman110
 

RE: Determination of pre-consolidation pressure by strain-energy method

Have never used it - it is outlined in Bowles 5th edition.  Why not check out logp'-loge?  There are some good papers out there that show this method - results in two straight lines and the intersection is the pre-consolidation pressure.

RE: Determination of pre-consolidation pressure by strain-energy method

(OP)
Thanks for the reply BigH
I will check out the suggested method and also dig more into the Strain-Energy method.  I will keep everyone posted of the outcome.  Meanwhile, if anybody has more comments, it is greatly appreciated
 

RE: Determination of pre-consolidation pressure by strain-energy method

Pacheco Silva's method from south america is also convenient to use and also independent of the graph scale.

Pacheco Silva, F. 1970. A new graphical construction for determination of the pre-consolidation stress of a soil sample. In Proceedings of the 4th Brazilian Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, Brazil. Vol. 2, No.1, pp. 225–232.

RE: Determination of pre-consolidation pressure by strain-energy method

I've told this story before - but Casagrande used to consult with my company back in the late 60s as our President at the time was a former student.  He came up to Toronto and an eager young engineer showed him all these beautiful Casagrande constructions he had done on quite a number of consolidatoin tests.  Casagrande looked at them and suggested a few changes here and there . . . the engineer asked him - "But, I did them according to your method."  Casagrande replied that, yes, you did but the construction method was developed to "teach" my students how basically to estimate it.

RE: Determination of pre-consolidation pressure by strain-energy method

(OP)
Hello everyone, thanks for the reply.

BigH, I am not sure if I understand the meaning of your story correctly.  Did Casagrande mean his method is just estimation or there is something else that I am missing?

In respect to the strain-energy method, I have done some research and so far it appears a good secondary/confirmatory method.  However, I am not done reading and cannot come to a final conclusion yet.  I will keep everyone posted when I have finished reading all the collected references.
 

RE: Determination of pre-consolidation pressure by strain-energy method

In looking at the various different types of curves one gets in consolidation testing (what about those that aren't "straight" in the primary consolidation range) - a lot is a matter of judgment of which he had plenty.  How does one take experience and judgment and teach students?  You make up a methodology that will get the student, typically, in the right ballpark.  The construction method he developed and taught was simply that, a teaching tool.   

RE: Determination of pre-consolidation pressure by strain-energy method

(OP)
Well said BigH.  Thanks for the reply

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