×
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

Shear strength of soil at plastic limit

Shear strength of soil at plastic limit

Shear strength of soil at plastic limit

(OP)
the shear strength of soil at liquid limit is 1.67 kPa and its penetration is 20 mm. It is alleged that the shear strength of soil at plastic limit is about 167 kPa. Why is the penetration of the soil at plastic limit is very variable?

RE: Shear strength of soil at plastic limit

Can you rephrase the second question - it doesn't read quite right and want to respond succinctly (for once!!)

RE: Shear strength of soil at plastic limit

I have to agree, there's not enough information to answer this question.  The soil type has to be defined (i.e., what's the sand content), the method of a "penetration" test has to be defined, who is alleging what and what is the basis for the allegation, what is the PI, and what is the confining stress?  These are just what comes to mind, but as it stands, it's hard to put your question into context. . . .

f-d

¡papá gordo ain’t no madre flaca!

RE: Shear strength of soil at plastic limit

One question, who is saying the soils shear strength is 167kPa. I have just been having a conversation [over a completly seperate project] with another engineer in our office over the likley shear strength of a soil at it's plastic limit, and he showed me a figure based on the liquidity index of a soil. This suggests that a soil at its plastic limit would have a shear strength of around 100 kPa [80 to 120 ish. I don't have a copy of the figure to hand, but the relationship forms a parabolic curve, which compares well to historical data of the drop in shear strength with increasing moisture above the plastic limit.

RE: Shear strength of soil at plastic limit

iandig:  I have seen the 170 kPa (or 200 kPa) before - see the abstract of a paper in the ASCE Geotech and Geoenvironmental Journal by Sharma(2003):

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JGGEFK000129000008000774000001&idtype=cvips&gifs=yes

The actual paper gives pretty good background references with Skempton being involved early along with Wroth. Of course, in 2005, there was some dissent and closure by the authors.

RE: Shear strength of soil at plastic limit

1.67 kPa is only 35 psf.  I suspect a decimal got slipped.

RE: Shear strength of soil at plastic limit

1.67 kPa is the "Su" value at liquid limit - most suggest that at plastic limit is is 100*Su(LL).  How the 1.7 and 170 have come up.  The paper by Sharma explains pretty well.

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