Talk:Shear strength (soil)

message: —Preceding unsigned comment added by 91.143.113.102 (talk) 10:08, 13 February 2009 (UTC)

message: Two points seem missing in this article.  Cohesion is not a function of negative pore pressure; it is caused by diagenetic forces between the solids in soil.  Apparent cohesion is caused by negative pore pressure; that force dissipates as the negative pore pressure is satisfied and the soil shifts to the drained condition.  Secondly, φ is the internal friction angle.  It is not a resistive force.  The resistive force from the friction angle is N*tan(φ); the resistance is proportional to the overburden pressure, N.
The term 'angle of internal friction' is prevalent in older literature, but is slightly misleading. The phi angle in soils is brought about by a more complex interaction of particles than the term 'friction' suggests, particularly in cohesive soils, but also in granular soils, where confining pressure, initial density, particle shape and angularity, orientation of particles, and physico-chemical effects such as cementation and bonding influence the phi angle, and ultimately the shear strength of a soil. A more 'correct' and generic term which should be used is 'angle of shearing resistance', as it encompasses all these effects not merely Coulomb friction. 
In the least, Friction should link to the main Wikipedia friction page: http://en.wikipedia.org/wiki/Friction
I'd suggest shear strength be expanded or carefully linked to other pages that cover failure criteria;  Linking to pages on Mohr-Coulomb Theory http://en.wikipedia.org/wiki/Mohr-Coulomb_theory, and for undrained shear strength, Tresca http://en.wikipedia.org/wiki/Henri_Tresca. Plasticity, http://en.wikipedia.org/wiki/Plasticity_%28physics%29, and Yield http://en.wikipedia.org/wiki/Yield_%28engineering%29 as general concepts for defining shear strength. But individual pages specific to shear strength of soils (for example) could be created, since there is much to expand on in this area.
GeoEng 09:05, 11 March 2007 (UTC)
replies: text: Thanks for your contributions; I'll try to help you out if I have time. Basar 19:53, 11 March 2007 (UTC)
replies: text:  Added some references and further info relating to cohesion and friction from those references. Really its just one actual reference at this stage (ref 2) by Prof. Schofield, and the others are cited in that document. May add some stuff from Prof. Burland if I get around to it, on 'post rupture' strength. This document needs some figures... i'll need to get around to those as well:) —The preceding unsigned comment was added by GeoEng (talk • contribs) 00:43, 18 March 2007 (UTC)
replies: text: I am not sure I agree re. the cohesion concept presented in below--it may be true for non-cohesive sils, but for coehsive soils ex. "fat clays", inter-particle attraction forces would cause C to be non-zero at zero confining stresses.  In otherwords, other than diagenetic forces, there is the plain old inter-particle attraction to consider--no?  Please let me know why I may be mistaken. Pathikoll 10:18, 20 July 2007 (UTC)
thread_title: Missing points

message: It seems to me that shear strength of soils should have its own article, perhaps shear strength (soil) or shear strength of soil. I'll move it if no one objects. Basar 19:53, 11 March 2007 (UTC)
replies: text: Good idea. Still need to leave the basics at this site with a "Main article" link. I have a preference for Shear strength (soil), but, eh, no big yank one way or t'other. ZueJay (talk) 20:05, 11 March 2007 (UTC)
thread_title: Move soils information

message: I would like to make a clarification re. the statement in the article that I have copied below:
"However, what is being plotted is not "true" cohesion, but is actually due to interlock of particles."
While this is no doubt possible for sands, for clays the cause is not so much intelock of particles, but rather inter-particle attractive forces.  These are not quite the same and I would like to distinguish between the two if there is no objection.
Pathikoll 18:09, 19 July 2007 (UTC)
thread_title: Clarificaton

message: Could expand on measurement e.g. by vane, Torvane.
—DIV (128.250.204.118 09:15, 10 October 2007 (UTC)
thread_title:  Measurement 

message: There seems to be a lack of understanding of the difference between the critical state and the steady state.  I am personally in contact with both Andrew Schofield and Steve Poulos, the two representatives of these respective states.
Thus the Critical State occurs at the quasi-static strain rate.  It does not allow for differences in shear strength based on different strain rates.  Also at the critical state, there is no particl alignment, all grains presumed to have broken to form spherical shaped grains.
The steady state can occur at any different strain rate, but has a slightly different value depending on the strain rate at which it is measured.  Thus the steady state shear strength at the quasi-static strain rate would seem to correspond to the critical state shear strength.  But it does not as the steady state does not assume that grains are crushed to form spherical particls. Rather it states that the grains align in the direction of shear, forming a special structure called the steady state structure.  —Preceding unsigned comment added by Pathikoll (talk • contribs) 15:35, 25 November 2007 (UTC)
thread_title: Critical State Vs. Steady State

message: Am moving all notes to references, and linking them in-line using Harvard Citation already in place  —Preceding unsigned comment added by Pathikoll (talk • contribs) 15:55, 1 November 2007 (UTC)
thread_title:  Maintanance 

message: Equations should conform to accepted formatting convention, such as . —DIV (128.250.80.15 (talk) 02:30, 25 July 2008 (UTC)
thread_title:  Formatting 

message: This is the policy to write about own research Wikipedia:NOR#Citing oneself sanpaz (talk) 15:27, 27 May 2010 (UTC)
thread_title:  Writing about own research 

message: I would like to add the two external connections, which are down shown. Do please notice both are NOT companies or general universities themselves adverting or driven by advert sites and  however they belong to the two prominent researchers in the field of critical state and the field of steady state soil mechanics. If there are no objections on the following 30 days, I add (in this order.)
http://www2.eng.cam.ac.uk/~ans/
http://soilmechanics.us
Efischer80 (talk) 14:23, 28 May 2010 (UTC)
thread_title:  External Links 

message: Recent changes use secondary sources.  Dilute credibility of article.
Ex.: The theoretical state at which the shear stress and density remain constant while the shear strain increases may be called the crtical state [1][2][3] , steady state, or residual strength.
This should refer Roscoe, Schoefield and Wroth,  and Poulos--not a text book or secondary compilation.
:Not sure I agree about lack of value of secondary sources. (1) Inclusion in recent books by leaders of the profession (e.g., Mitchell, Santamarina, Bolton) provides evidence of acceptance. (2)Text book explanations of the theory are more mature and accessible to others -- these are places where the reader should be directed to look for more details. (3) There are many theories of shear strength that have original sources. The theories that make it into text books are the encyclopedic ones. I suppose there is an article about the use of secondary issue somewhere. Would it be appropriate to move references to the text books in a suggested list for further reading instead of listing them as primary references?Blkutter (talk) 00:27, 19 November 2010 (UTC)
replies: text: Please look at http://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary.2C_secondary_and_tertiary_sources . This policy suggests that Wikipedia articles *should* generally be based on secondary sources, not primary or tertiary ones. Advanced text books and review articles may be considered to be secondary articles. Blkutter (talk) 01:02, 19 November 2010 (UTC)
replies: text: I agree wit jankar68 as in soil mech is there 100s of text books and people this article misuse to push their (or their professors) textbooks.  The txt book you mention is quite unknown, whereas the references concerned are "cannonical".  Also, the statement is wrong as the steady state is not this condition of shear stress and density remaining constant, but additional and very important, has strain rate and void ratio constant also.  If this book makes this statement then it straightway shows it is badly flawed as a reference.(Efischer80 (talk) 13:24, 20 February 2011 (UTC)

text: Please look at http://en.wikipedia.org/wiki/Wikipedia:No_original_research#Primary.2C_secondary_and_tertiary_sources . This policy suggests that Wikipedia articles *should* generally be based on secondary sources, not primary or tertiary ones. Blkutter (talk) 09:26, 8 February 2011 (UTC)
replies: text: disagree--finding provides important, independent basis of steady-state and also first constitutive model there on based.  Also read the Wikipedia article you mention above in detail and I from it quote: "primary sources are permitted if used carefully." and here the wording is quite careful. Please, if not so, suggest the changes you prefer to modify it to.  Also see http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.001 to further the credibility.(Efischer80 (talk) 13:24, 20 February 2011 (UTC)
replies: text: 2009 (2 yrs.) long enough. GeoLetters publishes w/in 6 weeks of sub.Jankar68 (talk) 15:18, 11 March 2011 (UTC)
replies: text:  What does the Geoletters publication time (a publisher of original research) have to do with Wikipedia (a tertiary reference)?  — Preceding unsigned comment added by Blkutter (talk • contribs) 07:17, 19 March 2011 (UTC)

text: I agree that we should only put in correct, well accepted material.   From what I understand, Wikipedia considers secondary references to be perhaps the best indication that the material is correct and accepted. If you have a more objective way to distinguish correct and incorrect references, please explain. Blkutter (talk) 18:20, 28 March 2011 (UTC)
thread_title:  Secondary Sources 

message: Fol. stmnt. imprecise:
This idea was extended to laboratory data in the empirical SHANSEP (stress history and normalized soil engineering properties) method.(Ladd & Foott 1974). 
Shd b:
This idea was systematized with the empirical SHANSEP (stress history and normalized soil engineering properties) method.(Ladd & Foott 1974). 
Will chg in 2 wks if no obj.
Jankar68 (talk) 16:53, 22 November 2010 (UTC)
thread_title:  Correction to this statement 

message: Propose mod. to the Steady State entry as follows:
1) "Steady state theory" -> "Steady state/dynamical systems theory"
2) >>In fact, Joseph (Joseph 2009) used this strict definition of the steady state to describe soil shear as a dynamical system.
to:
Dynamical systems are ubiquitous in nature (the Great Red Spot on Jupiter is one example) and mathematicians have extensively studied such systems.  Joseph (2009) used the strict definition of the steady state to describe soil shear as a dynamical system.  Joseph (2012) showed that the underlying basis of the soil shear dynamical system is simple friction.  These findings describe a new paradigm for soil shear that is at once both simple and powerful.
[note: point 2 is based on email received]
3) Add a link to the critique of critical state soil mech.
Unless hear otherwise, will target March 10 (30d since my orig. proposal) Jankar68 (talk) 15:47, 17 February 2012 (UTC)
thread_title:  phys. basis of dyn. sys. model 

message: This was an important discover--earliest known proposed by Henkel and then Perry in 1957.  Suggest adding the following:
"Perry and Henkel were one of the earliest who proposed that soil shear data could be usefully normalized by the initial confining stress."
Will add in 30 d unless I hear otherwise.  This basic finding was later fine tuned to become SHANSEP.
Jankar68 (talk)
Done.
Jankar68 (talk) 11:56, 22 October 2012 (UTC)
thread_title:  Normalisation of stress-strain curve 

message: There is by Dr. Joseph offered a online course (self-study, and seemingly free) on the dynamical systems based soil mechanics (dssm) approach.  The link: http://www.soilmechanics.us/dssm/  Since it is free to use and seems useful, I propose to add it to the external link.  Let me by 30 days know accordingly if ok.
Efischer80 (talk) 00:32, 25 November 2013 (UTC)
thread_title:  Dynamical Systems--Self Study Course 

message: I am not a scientist so I had to look up the meaning of dilatant. However, the article dilatant and the OED definition are not obviously related so I am asking for someone to clarify (add a synonym or brief definition) dilatant or use another more widely known term. Thanks. Jim Derby (talk) 15:38, 17 March 2015 (UTC)
thread_title:  Dilatant