Using "Peck's Method" for design pressure
Using "Peck's Method" for design pressure
(OP)
I'm studying for my Civil P.E. and ran across a question that said to use Peck's method to find the maximum design pressure. None of my reference material says anything about this method and an internet search has also been fruitless. Any good references would be helpful.
Also looking for any good recommendations on passing the exam in April. Are most of the questions math based equation questions or are there a lot of "non-quantitative" type questions? (I will take water resources in the afternoon.)
Also looking for any good recommendations on passing the exam in April. Are most of the questions math based equation questions or are there a lot of "non-quantitative" type questions? (I will take water resources in the afternoon.)





RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
With K. Terzaghi and G. Mesri, Soil Mechanics in Engineering Practice, 3rd Edition
With W.E. Hanson and T.H. Thornburn, Foundation Engineering
With A. Casagrande, L. Bjerrum and A.W. Skempton, From Theory to Practice in Soil Mechanics
http://w
RE: Using "Peck's Method" for design pressure
this is the reference list for the California exam which includes Peck's text
RE: Using "Peck's Method" for design pressure
So what is "Peck's method" of finding maximum design soil pressure? I read those texts and do not remember any method with that label.
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
For the hundreds of jobs I have done, and knowing others in the field,it never is used.
In my view settlement usually governs over shear failure. More often than not, some form of presumptive bearing pressure as from a building code is used. On rare occasion, pressure meter allows a higher number for design.
But for some exam, probably written by a college professor, he had better know it.
RE: Using "Peck's Method" for design pressure
Thanks for the many replies. Here is the actual question:
A braced excavation is cut 12 ft deep in a clay with a unit weight of 125 lbf/ft3 and a cohesion of 3000 lbf/ft2. Using Peck’s method, the maximum design pressure is most nearly...
I guess that is a good point to note from "oldestguy". Some stuff is just very unlikely to be applicable in the real world. I know I'm not going to study and learn everything. I have made lots of notes in my CERM for esoteric stuff but if it is that far out there, I guess I will have to learn to let some of it go and not worry about it.
RE: Using "Peck's Method" for design pressure
Note major modifications to the AEPDs (as used today) by Henkel (1971) and FHWA (1998).
Google "apparent earth pressure" and you'll find more...
Etc Etc
RE: Using "Peck's Method" for design pressure
In the lateral pressure case, Peck did some measuring of lateral earth pressures for systems like this in Chicago and he probably is asking for, not the average, but the highest unit lateral design pressure, not necessarily saying he wants it located with respect to vertical.
In that case, I would assume the trapezoid shown on page 347 and 350 of "Soil Mechanics in Engineering Practice" by Terzaghi and Peck, (My editon is copyrighted 1948) is what he is after. That I have used.
Then again, look at page 148 and you will see that there is a formula for an unsupported cut height. But is that a Peck method? Probably not.
An unconfined compressive strength of 3 tons per sq. ft., is a pretty stiff clay and maybe it will stand OK for 12 feet, unsupported. Chances are it has experienced shrinkage in the past and now you have a rather stiff clay with lots of cracks in it.
I once was almost buried in a 14 ft. test pit trench in that sort of stuff, so I'd not trust any stiff clay standing by itself unsuported.
Gets pretty sticky doesn't it?
I'd stay with the trapezoid, but given no phi value, you have to assume one.
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
<Thread_drift>
I agree with you about the loss of our history as a profession. Especially sad considering how young we really are. As an example, I recently received a scanned copy of firsthand notes of Terzaghi's 1955 Applied Soil Mechanics course and his 1959 Engineering Geology course. Nobody seems to know what to do with them, or want to deal with them.
</Thread_drift>
RE: Using "Peck's Method" for design pressure
Can you share the notes here with us? I'm sure Terzaghi won't mind.
RE: Using "Peck's Method" for design pressure
SlideRuleEra has generously agreed to host interesting materials on his website www.slideruleera.net for EngTips folks in the past.
SRE, would you be intersted in this?!
Jeff
RE: Using "Peck's Method" for design pressure
The files are somewhat large, and would need to be hosted somewhere. 3 PDFs altogether, totaling 20 MB.
I'm sure Terzaghi won't mind, but I'll need to check with the note-taker or his proxy. I expect he won't either, but I need to make the inquiry.
Is there a way to email folks here without spamming the boards?
RE: Using "Peck's Method" for design pressure
I once had a copy and gave it away, but could retrieve it if necessary.
Don't know the printing date, but got it from former employer who apparently was in his class about 1930ish. at MIT or Harvard.
Would be a nice thing if translated and reprinted I suppose.
RE: Using "Peck's Method" for design pressure
Please the send the notes to me (if permitted) at jtdonvilleAThotmailDAWTcom (change uppercase words to appropriate symbols). I can forward to SRE or another if they agree.
Jeff
RE: Using "Peck's Method" for design pressure
Good luck on your exam.
f-d
¡papá gordo ain’t no madre flaca!
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
fatt-dad AT comcast DOT net
¡papá gordo ain’t no madre flaca!
RE: Using "Peck's Method" for design pressure
The method applies:
1) If applies to excavation >>20ft deep (Fang) (That means your question would not be applicable in a practical situation)
2) The piezometric surface is below the bottom of the excavation (Fang)
3) an artificial loading designated as 'apparent' is applied (Fang, Bowles)
For soft to medium clay Pressure: P = 1.0Ka x unit wt x H
(The unit wt in this case is NOT the effective unit wt)
Maximum pressure occurs at 0.25H, and is constant below that depth.
Ka = 1 - m((2qu)/yH) (Fang)
Where m is a reduction factor
For stiff fissured clay:
P = Kap x y x H (Bowles)
where Kap = 0.2 to 0.4
In the case your question,you have stiff clay (qu = 6000psf as was pointed out by "Oldestguy". Note: c = qu/2)
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure
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RE: Using "Peck's Method" for design pressure
RE: Using "Peck's Method" for design pressure