Talk:Soil mechanics

Bearing capacity

probabilistic methods in determining the bearing capacity

Editing

This is one of those very general articles. I am using this as a general template and expanding the subsections. --Zeizmic 15:07, 11 September 2006 (UTC)

More editing

Hi, I want to dramatically edit the soil mechanics page. Any objections if I do the following:

• Rewrite the introduction.
• Delete Shear Strength section, and merely link to Shear_strenth, and other relevant topics such as friction, Coefficient_of_friction -the topic as written appears to be covered mostly by these links, and this avoids doubling up.

GeoEng 19:35, 11 March 2007 (UTC)

The intro could definitely use a rewrite as it does not really explain what soil mechanics is as much as who uses it or where it is used. As for dumping sections on shear strength, etc., the usual convention is to pare those down to one paragraph with a link to the main article. A good example of this exists at Civil engineering where each branch has a small description and a link to the "main article." All-in-all, sounds all right; and you know other editors are (almost) always watching... ZueJay (talk) 19:45, 11 March 2007 (UTC)

Indeed, I agree with Zuejay, and welcome to Wikipedia GeoEng. Basar 19:48, 11 March 2007 (UTC)

OK thanks. I'll try not to annoy anyone with my edits. In terms of re-organising the geotech pages, may I suggest using the Burland Triangle (From his Nash lecture: "The Teaching of Soil Mechanics, a personal view", 1987. Proc. 9th Conf. Soil Mech & Found Eng) as a rough guide. It essentially separates Geo-Engineering into three main areas, linked to each other. These are:

• 1. Ground Profile: Genesis, SI, Ground Description (Minerology; Classification; Ground water; geological processes).
• 2. Soil Behaviour: Laboratory & Field Testing, Measurement & Observation (Particulate behaviour; effective stress; stress paths; compressibility; Ko, preconsolidation; permeability, consolidation, creep; Drained strength, dilatant & contractant behaviour; excess pwp; undrained strength; critical state framework)
• 3. Applied Mechanics: Idealisation, conceptual, physical, analytical modelling (Stress, strain, elasticity, plasticity, limit equilibrium, limit analysis, finite element analysis, soil constitutive models)

At the nexus of the three points it has: Practice: (Empiricism "based on well winnowed experience"; Insitu testing; Atterbergs; bearing capacity; earth pressure; geotechnical processes;(other design aspects) etc).

"soil mechanics", whilst retaining links to "Ground Profile" & "Practice" topics, it essentially is better described as covering Soil Behaviour and Applied Mechanics groups. In this sense, I think items relating to "Ground Profile" and "Practice" should be moved to link directly from Geotechnical Engineering (eg. Ground Investigation, Bearing Capacity -comes under Foundation Design, Slope Stability -comes under Slope processes), whilst aspects relating to Soil Behaviour and Applied Mechanics should stay within Soil Mechanics. This is fairly logical, and Geotechnical Engineering already has the more practical (less theoretical) aspects.

I think once the framework is there, we can work on developing each subgroup, gradually becomming more detailed as we (and others) see fit. GeoEng 20:52, 11 March 2007 (UTC)

Some good suggestions here - have moved this over to Wikipedia talk:WikiProject Geotechnical engineering where it can be more readily discussed. I need to reread this and consider it a bit more before voicing a reasonably thought-out opinion. ZueJay (talk) 21:01, 11 March 2007 (UTC)

Editing of Shear Strength and Soil Liquefaction

The section of soil liquefaction needs to get incorporated into shear strength. And I agree with the previous comments: the shear strength needs to be simplified and referenced to the main article about it. —The preceding unsigned comment was added by 70.74.26.76 (talk • contribs) 03:42, July 20, 2007 (UTC)

Ya, a lot of this article has not been touched in a very long time, including the shear strength section. Feel free to make whatever modifications you see fit. -- Basar (talk · contribs) 03:50, 20 July 2007 (UTC)

I took the liberty to make major changes to the Shear Strength section. The idea of this entry is to address in a logical fashion all the aspects related to shear strength of soils: Definition, importance in soil mechanics, factors affecting shear strength and laboratory tests. A more thorough explanation of shear strength should be done in the Shear Strength article. Please discuss if this changes are valid and how they can be improved.

The Soil Liquefaction section was deleted, and it was just mentioned in the Shear Strength article with a link to the main article. Soil Liquefaction is a particular problem of Shear Strength. Please forgive the major edits. I did not know how to be more subtle on the edits.

Please comment. sanpaz75 00:33, 21 August 2007 (UTC)

The changes seem OK to me. I don't mind major edits. -- Basar (talk · contribs) 01:28, 21 August 2007 (UTC)

Re-defining the scope of the Soil Mechanics and Geotechnical Engineering articles

This is what I propose: The Soil Mechanics article should deal strictly with the basic theories of Soil Mechanics: Soil Structure, Soil Classification, Shear Strength, Seepage, Consolidation... Topics such as: Soil Liquefaction, Ground Investigation etc. belong to the Geotechnical Engineering article.

I have not decided if Slope Stability, Bearing Capacity and Lateral Earth Pressure should go into the Soils Mechanics article or the Geotechnical Engineering article. I think the former is more appropriate.

Please comment sanpaz75 00:51, 21 August 2007 (UTC)

Yes, I think you are right about the split between soil mechanics and geotechnical engineering. I have tried to follow this distinction too when I was sorting those respective categories: Category:Soil mechanics and Category:Geotechnical engineering. It would seem to me too that slope stability, bearing capacity, and lateral earth pressure would be best in soil mechanics as they don't involve specific design recommendations. I'll try to clean up somethings in this article too to try to help. -- Basar (talk · contribs) 01:26, 21 August 2007 (UTC)

Definition of Soil

I have modified the first section of this article titled "Basic Soil Characterisitcs". I based the definition on the book by Mitchell (see references). It explains that the soil has 3 phases, and explains each phase. A short introduction is given on soil mineralogy and soil structure. To continue with the same idea for other section, I suggest opening a new article Soil(engineering), which will expand all this concepts (mineralogy, structure, fabric, composition, interparticle forces etc). Please comment. Sanpaz 05:02, 17 September 2007 (UTC)

Yes, I would like to see those concepts expanded on too. I, however, would prefer to see the topics added to the article soil and the articles on types of soil like clay or sand. I have given my thoughts on the soil talk page, but they are essentially that I think the topic of soil should be integrated with other academic disciplines that deal with soil and because it is the standard way of dealing with this situation on Wikipedia. – Basar (talk · contribs) 05:57, 17 September 2007 (UTC)

Yes, I agree with you that the article soil should have all these concepts integrated. Geology, Pedology, and Geotechnical Engineering certainly use different definitions for the term soil. I think it is important to acknowledge this fact is some clear manner. Creating a Soil(engineering) page would address the specific aspects of soils that matter to civil engineers. Sanpaz 15:52, 17 September 2007 (UTC)

Major rewrite of entire soil mechanics article

I have taken the existing article and am reworking the whole thing. A link to my current draft of the rewrite can be found on my user discussion page http://en.wikipedia.org/wiki/User:Blkutter/Soil_Mechanics_Rewrite. Please take a look and let me know if you would be disturbed by such a wholesale change. Let me know if you think I should make the changes piece by piece or should I just move my new page into the old page. Please feel free to give me your suggestions here or on my user talk page. Blkutter (talk) 22:57, 12 August 2010 (UTC)

In the next week or so, I will begin moving the contents of http://en.wikipedia.org/wiki/User:Blkutter/Soil_Mechanics_Rewrite into this Soil mechanics page. In the mean time, feel free to work on that page or make comments her or on my user page.Blkutter (talk) 01:13, 29 August 2010 (UTC)

I just replaced the introduction and soil classification and gravimetric relations sections of the old soil mechanics article. I am planning to replace the whole article in about 3 chunks. You can look at my user page which has a link to the rest of the rewritten article.Blkutter (talk) 22:10, 30 August 2010 (UTC)

I just replaced the section on effective stress and added a lot of material on capillary action and soil classification. This goes through section 3 in the table of contents at the top of the page. next comes seepage, consoilidation and shear strength. I will move them when I get a chance in the next couple days. You can look at my user page which has a link to the rest of the rewritten article.BlkutterBlkutter (talk) 23:00, 31 August 2010 (UTC)

I just replaced the rest of the article. I encourage others to help polish this page at this time; here are some tasks I see

New graphics would useful(a grain size distribution curve, a sketch of curved failure envelope to illustrate how c and phi can overestimate strength, a nice photograph of soil grains, a sketch to illustrate concept of effective stress

some of the graphics could be improved.

references are not consistent in terms of their format.Blkutter (talk) 15:44, 1 September 2010 (UTC)

Recent developments

Will add following new section in 30 days. Plz comment.

I apologize for not responding sooner. The information below that you have added to the recent developments section describes very recent work of a single author P.G. Joseph and this work has not been widely cited in the literature. A Wikipedia article in general, and especially a basic article such as soil mechanics should not be used to promote recent research. Furthermore, much of this information is repeated on the shear strength (soil) page. Please remove it and reference the shear strength page instead of repeating it here. Blkutter (talk) 19:23, 8 October 2014 (UTC)

I am not happy to do this for the following reasons:

1. finding is fundamental

2. published in all the premier internationale journals with peer review

3. is not specific to just schear (applies everywhere)

4. Andrew Schofield is well known of his personal opposistion to the steady-state and thereon, his use of his ex. phd students to propogate his views while curtaining other views. Wikipedia is not a curtaining knowledge base.

5. Contra, finding is not "promotion".

6. Basis finding dated over five years and not contraindicated.

7. Science is not a "popularity" game.

Efischer80 (talk) — Preceding undated comment added 20:06, 12 January 2015 (UTC)

Agree with efischer. 5 years plus long enough for even academics to get of their butt. Finding is fundamental. Solomon1980 (talk) — Preceding undated comment added 23:19, 15 January 2015 (UTC)

I checked one of the references by Joseph in Geotechnique in google scholar https://scholar.google.com/scholar?cites=5985209865683255319&as_sdt=2005&sciodt=0,5&hl=en. That paper has six citations, and all of the citations are by Joseph himself to his own work. That means that the idea has not been adopted by any other scholars. Until the idea has been adopted, it should not be in wikipedia. You should be publishing your support of these ideas in journals instead of wikipedia. In contrast, Critical State Soil Mechanics has been published in many books and several of these books have thousands of citations. Joseph's work, even if it is fundamental, has not yet been accepted by the profession. I agree that science is not a popularity game, but wikipedia is not a place to publish new science that has not been accepted by a majority of scholars. There are many recent developments published in premier journals that are not cited by this wikipedia article. Why do you so strongly feel that DSSM is the most fundamental recent development? Blkutter (talk) 19:42, 20 July 2015 (UTC)

Yes, this is why it is in the "recent", i.e., neu section. What other finding is as fundamental as this one? I cannot recall any. Please advize and I can add that as well. Efischer80 (talk) 18:51, 9 July 2016 (UTC)

---

RECENT DEVELOPMENTS A recent development in soil mechanics is a model for soil behavior based on dynamical systems theory and referred to as Dynamical Systems based Soil Mechanics (DSSM). DSSM holds simply that soil deformation is a Poisson process in which particles move to their final position at random shear strains.

The basis of DSSM is that soils (including sands) can be sheared till they reach a steady-state condition at which, under conditions of constant strain-rate, there is no change in shear stress, effective confining stress, and void ratio. The steady-state was formally defined in Poulos (1981). Steve J. Poulos, then an Associate Professor of the Soil Mechanics Department of Harvard University, built off a hypothesis that Arthur Casagrande was formulating towards the end of his career. The steady state condition is not the same as the "critical state" condition.It differs from the critical state in that it specifies a statistically constant structure at the steady state. The steady-state values are also very slightly dependent on the strain-rate.

Many systems in nature reach steady-states and dynamical systems theory is used to describe such systems. Joseph (2009, 2010) showed that soil shear can be described as a dynamical system. Joseph (2012) showed that the physical basis of the soil shear dynamical system is a Poisson process in which particles move to the steady-state at random shear strains; Joseph (2014) generalized this--particles move to their final position (not just steady-state) at random shear-strains. Because of its origins in the steady state concept DSSM is sometimes informally called "Harvard soil mechanics."

DSSM provides for very close fits to stress-strain curves, including for sands. Because it tracks conditions on the failure plane, it also provides close fits for the post failure region of sensitive clays and silts (Joseph, 2012), something that other theories are not able to do. Additionally DSSM explains key relationships in soil mechanics that to date have simply been taken for granted, for example, why normalized undrained peak shear strengths vary with the log of the over consolidation ratio and why stress-strain curves normalize with the initial effective confining stress; and why in one-dimensional consolidation the void ratio must vary with the log of the effective vertical stress, why the end-of-primary curve is unique for static load increments and why the ratio of the creep value Cα to the compression index Cc must be approximately constant for a wide range of soils. Joseph (2013) has the details.

• Joseph, P. G. (2009), "Constitutive Model of Soil Based on a Dynamical Systems Approach" (PDF), Journal of Geotechnical and Geoenvironmental Engineering, vol. 135, no. No. 8, pp. 1155–1158, doi:10.1061/(ASCE)GT.1943-5606.0000001 {{citation}}: |issue= has extra text (help)
• Joseph, P. G. (2010), "A Dynamical Systems Based Approach to Soil Shear", Geotechnique, vol. LX, no. No. 10, pp. 807–812, doi:10.1680/geot.9.P.001 {{citation}}: |issue= has extra text (help)
• Joseph, P. G. (2012), "Physical Basis and Validation of a Constitutive Model for Soil Shear Derived from Micro-Structural Changes" (PDF), International Journal of Geomechanics, doi:10.1061/(ASCE)GM.1943-5622.0000209
• Joseph, P. G. (2013), Dynamical systems based soil mechanics (DSSM), a short self-study course
• Joseph, P. G. (2014), "Generalized soil deformation model based on dynamical systems theory", Geotechnical Research, vol. 1, no. No. 1, pp. 32–42, doi:10.1680/geores.14.00004 {{citation}}: |issue= has extra text (help)
• Poulos, S. J. (1981), "The Steady State of Deformation", Journal of Geotechnical Engineering, vol. 107, no. GT5, pp. 553–562

Efischer80 (talk) 21:18, 16 June 2014 (UTC)

added

Efischer80 (talk) 23:52, 17 July 2014 (UTC)

Pressure bulb

is a term frequently used in books on the subject. --Rainald62 (talk) 23:20, 16 May 2015 (UTC)

Layman's questions

I am curious about how it is that on flat ground soil builds up. Specifically why it is that on flat ground soil builds up to cover things that archaeologists later find. So far I seem to have found out that things being covered up is likely at the bottom of, for example, a hill. That makes immediate sense. I have also seen that wind can carry particles of whichever kind so that could explain some of it. Another thing that makes sense is if something is demolished on the ground in question or nearby. Any assistance you can give, such as links to articles will be gratefully received. --bodnotbod (talk) 19:40, 4 December 2016 (UTC)

I've been Googling and one thing that simply didn't occur to me would be plants decaying on the surface. I realise there's many other processes that could "add height" to land and I also found Excavation_(archaeology)#Site_formation, so I'm basically happy just with what I've discovered, so nobody need now reply. If somebody does, however, then I shall read the replies. --bodnotbod (talk) 20:34, 4 December 2016 (UTC)

River flooding is another mechanism which deposits soil on flat areas. Also, in areas with a dry season, sand dunes can move - about 8000 years ago, when San Francisco was an island, sand dunes moved enough to block an outlet to the bay, and built up to a height of over 100 feet in the years since then. Argyriou (talk) 16:01, 5 December 2016 (UTC)

Copyright problem removed

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