L1- Soil Classification 28-08-09

CLASSIFICATION OF SOILSLecture – 1 (28-08-2009)Lecture – 1 (28-08-2009)

By

Dr. H.B.NAGARAJ

Assistant Professor

Department of Civil Engineering

B.M.S. College of Engineering, Bangalore

Syllabus PART A

UNIT 3

3. CLASSIFICATION OF SOILSPurpose of soil classification, basis for soil classification

Particle size classification – MIT classification and IS classification, Textural classification

Unified soil classification and IS classification - Plasticity chart and its importance, Field identification of soils.

Dr. H.B.NAGARAJ, Asst Prof in Civil Engineering


CONTRIBUTORS TO THE GROWTH OFTHE GROWTH OF SOIL MECHANICS

1.KARL VON TERZAGHI 2.DONALD. W.TAYLOR2.DONALD. W.TAYLOR3.RALPH. B. PECK4.ARTHUR CASAGRANDE5.ALEC WESTLEY SKEMPTOM6.LAURITUS BJERRUM



KARL VON TERZAGHI

BornOctober 2, 1883Prague, Czech Republic

DiedOctober 25, 1963Winchester, Massachusetts, United St t f A i

THE FATHER OF SOIL MECHANICS

States of America



THE FATHER OF SOIL MECHANICS

Terzaghi had his basic

Education

Terzaghi had his basic education in Graz, Austria.

He received his degree in Mechanical EngineeringMechanical Engineering in 1904, even though his favorite subjects werefavorite subjects were geology, philosophy, and astronomy



astronomy.

Terzaghi after graduation fulfilled a compulsory one year military service.

While fulfilling his military obligationsWhile fulfilling his military obligations, Terzaghi translated and greatly expanded a popular English geology Early Lifeexpanded a popular English geology field manual into his native language, German.

Early Life

He returned to the Technical University in Graz for one year after thi d bi d th t d f lthis and combined the study of geology with courses on subjects such as highway and railway engineering



highway and railway engineering.

Early professional yearsHis first job was as a junior design engineer for the firm AdolHis first job was as a junior design engineer for the firm Adol

Baron Pittle, Vienna.He became involved in the geological problems the firm

facedfaced.He later focused on the design and construction of steel

reinforced structures. He embarked on an ambitious and challenging project to

construct a hydroelectric dam in Croatia, and a more chaotic project in St. Petersburg with great success.project in St. Petersburg with great success.

During six months in Russia, he developed some novel graphical methods for the design of industrial tanks, which he submitted as a thesis for his PhD at the university



submitted as a thesis for his PhD at the university.

Early professional yearsIn 1912 he moved to United statesIn the US on his own he undertook an engineering tour of major damIn the US, on his own, he undertook an engineering tour of major dam

construction sites in the West to gather reports and first-hand knowledge of the problems of many different projects.

When World War - I broke out, he found himself drafted into the armyWhen World War I broke out, he found himself drafted into the army as an officer.

After a short stint managing an airfield, he became a professor in the Royal Ottoman College of Engineering in Istanbul (now Istanbul y g g g (Technical University).

In 1925 he published much of this in his research findings, Erdbaumechanik auf bodenphysikalischer Grundlage (Fundamental Principles of Earth Mechanics) which revolutionized the field to great acclaim. It resulted in a job offer from the Massachusetts Institute of Technology, which he accepted immediately.



One of his first tasks in the USA was to bring his work to the attention of engineers.

Thi h d d t d b itiThis he proceeded to do by writing a series of articles for the Engineering News Record.

He found the facilities at MIT and set up a new laboratory geared to making measurements on soils with instruments of Later yearsmeasurements on soils with instruments of his own devising.

He entered a new phase of prolific bli ti d idl i dpublication and a rapidly growing and

lucrative involvement as an engineering consultant on many large-scale projects.



In 1938 Terzaghi emigrated to the United States and took up a post at H d U i it B f th d fHarvard University. Before the end of the war, he consulted on the Chicago Subway system the Newport NewsSubway system, the Newport News Shipways construction, and raising the Normandie, among others. Later years, g

He became an American citizen in March 1943.

He remained as a part-timer at Harvard university until his retirement in 1953 at the mandatory age of 70



in 1953 at the mandatory age of 70.

The American Society of Civil Engineers established in 1960 the Karl Terzaghi Award to an "author of outstandingAward to an author of outstanding contributions to knowledge in the fields of soil mechanics, subsurface

d th k i i d

Legacyand earthwork engineering, and subsurface and earthwork construction".

The Terzaghi and Peck Library, which is managed by the Norwegian Geotechnical Institute in Oslo Norway holds anInstitute, in Oslo, Norway holds an extensive collection of his papers.

The Mission Dam in British Columbia, Canada was renamed his honor as the



Canada, was renamed his honor as the Terzaghi Dam in 1965.

In 1936 Terzaghi served as the Chairman of the First International C f S il M h i dConference on Soil Mechanics and Foundation Engineering, which was held in Harvard University. y

On that occasion the International Society of Soil Mechanics and Foundation Engineering was founded AdministrativeFoundation Engineering was founded, Terzaghi was elected as its first president.

H ti d t h ld thi iti

Administrative Achievements

He continued to hold this position up to the Fourth International Conference at London in 1957.



Important Contributions to Soil Mechanics

Consolidation TheoryOne dimensional consolidation apparatusOne-dimensional consolidation apparatusEffective stress principleBearing capacity theoryBearing capacity theoryTunneling Classification and support system



Important Publications

Together with Ralph Peck, Karl Terzaghi, published in 1948 the g , pmost influential text book in geotechnical engineering: “Soil Mechanics in Engineering Practice”Engineering Practice .A Third Edition of this book, with additional co-author, Gholamreza Mesri, was published in 1996.



Influence of Terzaghi’s work on the Soil Mechanics Profession

Not only did Terzaghi start soil mechanics, but also he exerted a profound influence on it until his death.

T d b f h di d h dili tl kiTwo days before he died he was diligently working on a professional paper.

Terzaghi’s writings contain significant contributions g g gon many topics, especially consolidation theory, foundation design and construction, cofferdam analysis and landslide mechanismsanalysis, and landslide mechanisms.

Probably Terzaghi’s most important contribution to the profession was his approach to engineering

bl hi h h t ht d d t t dDr. H.B.NAGARAJ, Asst Prof in Civil Engineering


problems, which he taught and demonstrated

With the death of Karl Terzaghi on October 25 1963 the engineeringOctober 25, 1963, the engineering profession lost one of its most eminent and colorful personalities, the founder of soil mechanics



of soil mechanics.

Ralph B. Peck

BornOctober 23, 1912

BornWinnipeg, Canada

DiedFebruary 18, 2008Albuquerque New MexicoDied Albuquerque, New Mexico



Education

Civil Engineering Degree in 1934Doctor of Civil Engineering Degree in 1937Both degrees from Rensselaer Polytechnic Institute in Troy, New York.



Professional Career of Prof R.B.Peck

1937 to 1938 - structural detailer for American Bridge Company.

1938 39 Laboratory assistant to Arthur Casagrande at Harvard University1938-39 - Laboratory assistant to Arthur Casagrande at Harvard University

1939 to 1942 - Assistant subway engineer for the City of Chicago, representing Karl Terzaghi who was a consultant on therepresenting Karl Terzaghi who was a consultant on the Chicago Subway Project

1942 - joined the University of Illinoisj y

Continued as Professor of Foundation Engineering from 1948 to 1974



Professional Achievements of Prof R.B.Peck

An acclaimed international expert in the field of soil mechanics, Ralph Peck has helped to change the face of the p gEarth through his discoveries of the way soils behave.

Through his work on the Chicago subway in the early 1940s he emerged

fas one of the undisputed leaders in the development and practice of soil mechanics and foundation engineering.



g g

As a distinguished professor at the School of Engineering of the

Professional Achievements of Prof R.B.PeckAs a distinguished professor at the School of Engineering of the

University of Illinois, he conducted field and laboratory research on stabilization of railroad beds and embankments, the mechanics of earth dams, the stability of retaining walls, and the settlement ofearth dams, the stability of retaining walls, and the settlement of foundations.

Peck has served as a consultant for major foundation projects j p jthroughout the world, from the Trans-Alaska Pipeline, to rapid transit systems in Chicago, San Francisco, and Washington, to dams in Turkey and Greece, to the Dead Sea dikes in Israel.

President Ford awarded Peck the National Medal of Science in 1974.



Professor Peck o esso ecregularly returned to the University of Illinois twice each year to give a series of lectures and to continue l i ticlose association

with students and faculty members.



Arthur Casagrande

August 28 1902Born

August 28, 1902Austria

1981Died

1981United States



Professional CareerHe worked at the Bureau of Public Roads and as

a Research Assistant under Terzaghi at MITa Research Assistant under Terzaghi at MIT.While at MIT, he worked on soil classification,

shear testing, and frost action in soils.He was the "right hand" of Terzaghi for several

years and made, or contributed to making, the fundamental developments of Soil Mechanics. p

He later became a Professor of Soil Mechanics at Harvard University.

Many of his students were inpired by CasagrandeMany of his students were inpired by Casagrande and entered the field of Soil Mechanics; these men have later become the creators of the Geotechnical E i i fi ld k i d



Engineering field as we know it today.

Researcher

Being a pioneer Professor Casagrande worked on theBeing a pioneer, Professor Casagrande worked on the fundamental problems of Soil Mechanics, such as soil classification, seepage through earth, and shear strength.

I i f h h "A Li " h l i iIt is safe to assume that the "A-Line" on the plasticity chart is after "Arthur.“

Most geotechnical engineers, haven't seen half as many g g , ydams he worked on.

To honor his lasting contributions to this area of geotechncial engineering his former students have createdgeotechncial engineering his former students have created "Embankment-Dam Engineering -- the Casagrande Volume" (Wiley, 1974).



INDEX PROPERTIES OF SOILS

1.Water content2 S ifi G it2.Specific Gravity3.Particle Size distribution4 Atterberg limits4.Atterberg limits5. In-situ density6.Relative densityy



Particle Size DistributionParticle Size Distribution

SIEVE ANALYSIS:TEST PROCEDURE

(# 80 )(# 80 mm)

Sieve Analyses(# 4.75 mm)

Sieve Analyses

(# 75 µm)



Particle Size Distribution

HYDROMETER:TEST PROCEDURE

Dispersing agent used is a solution sodium hexametaphospate shall be used Dispersing agent used is a solution sodium hexametaphospate shall be used

in distilled water at a rate of 40g of sodium hexametaphospate per litre of

solution. The above pictures shows the of preparation of Blank SolutionDr. H.B.NAGARAJ, Asst Prof in Civil Engineering


About 50g of the sample is taken into a 250mL beaker and cover with 125mL About 50g of the sample is taken into a 250mL beaker and cover with 125mL

of the Dispersing solution and allow it to soak for about 16 hours.



At the end of the soaking period transfer the solution into the dispersion

cup and stir it properly by the stirring apparatus for about a minute



After the dispersion, dilute the soultion to 1000ml.By

l i th l t f th li d t it idplacing the palm on top of the cylinder turn it upside

down for about a min. Take hydrometer readings at

2 5 15 30 60 250 and 1440 min Note the temperature2,5,15,30,60 250 and 1440 min. Note the temperature

each time.

LIQUID LIMIT :TEST PROCEDURE



Liquid Limit Definition

• The water content at which a groove cut in a soil paste will close upon 25 repeated drops of a brass cup with a rubber base



Soil Constants : Test Procedure

The soil is prepared as per the Indian Standards, the soil is passed through

a 425µm sieve is taken to a required amount and mixed with water until a

uniform consistency is achieved.y



The liquid limit device is calibrated such that the height fall is 13mm. The

soil is then taken into the cup such that the surface is parallel to thesoil is then taken into the cup such that the surface is parallel to the

horizontal. Then using a grooving tool the soil is taken out such that the

grooving tool is always perpendicular to the cup at the time contactgrooving tool is always perpendicular to the cup at the time contact.Dr. H.B.NAGARAJ, Asst Prof in Civil Engineering


• View showing groove cut ingroove cut in soil paste with standardstandard grooving tool



• View showing the closure of the groove over a distance of 1/2” (13 mm)



Blows are given such the handle is revolved at 2 revolutions per second.

Th f bl i d f th il t f il i t d d l lThe no. of blows required for the soil to fail is noted and a sample along

the failure plane is taken for moisture content readings. This is done for

different blows ranging between 15 to 35 blows.Dr. H.B.NAGARAJ, Asst Prof in Civil Engineering


LL Test Results% Interpolate LL water content

onte

nt, % LL= w% Interpolate LL water content

at 25 blows

wat

er c

o

Log N

w

25Log N



Plastic Limit Definition

• The water content at which a soil changesThe water content at which a soil changes from a plastic consistency to a semi‐solid consistencyconsistency

• Defined by Laboratory Test concept developed by Atterberg in 1911by Atterberg in 1911.



Plastic Limit Test

• The water content at which a 1/8” (3 mm) thread of soil can be rolled out but it begins to crack and cannot then be re‐rolled



Definition of Plasticity Index

Plasticity Index is the numerical difference between the Liquid Limit and the Plastic Limit water contents It represents theLimit water contents. It represents the range in water contents over which a soil behaves in a plastic manner

w% LLPL

PI = LL - PLplastic (remoldable)



( )

Definition of Non-plastic

• If the soil has a PI of zero, or either of the Atterberg tests cannot be performed, the soil is said to be non‐plastic



CLASSIFICATION OF SOILS



IntroductionSoil classification is theSoil classification is the

arrangement of soils into different groups such that the soils in agroups such that the soils in a particular group have similar behaviour.

As there are a wide variety of soils covering earth, it is desirable t t ti l if th ilto systematize or classify the soils into broad groups of similar behaviour



behaviour.

Soils, in general, may be classifiedas cohesionless and cohesive or as

i d d fi i dcoarse-grained and fine-grained.These terms, however, are too

general and include a wide range ofgeneral and include a wide range ofengineering properties.

Hence, additional means of,categorization are necessary tomake the terms more meaningful inengineering practice.

These terms are compiled to formsoil classification systems



soil classification systems.

Purpose of Classification of SoilsNatural soil deposits are never homogeneous inNatural soil deposits are never homogeneous in

character; wide variations in properties andbehaviour are commonly observed.

Deposits that exhibit similar average properties,in general, may be grouped together, as a class.

Th h l ifi ti f il bt iThrough classification of soils one can obtain anappropriate, but fairly accurate, idea of the averageproperties of the soil group or a soil type which isproperties of the soil group or a soil type, which isof great convenience in any routine type of soilengineering project.



g g p j

Purpose of Classification of Soilscont’d

From engineering point of view,classification may be made based on theysuitability of a soil for use as a foundationmaterial or as a construction material.

For complete knowledge of soil behaviourof soils all the engineering properties areof soils, all the engineering properties aredetermined after conducting a large numberof tests.



Purpose of Classification of Soilscont’d

A classification system thusprovides a common languagebetween engineers dealing withsoils.

It is useful in exchange ofinformation and experienceinformation and experiencebetween the geotechnicalengineers.



g

Purpose of Soil classificationClassifying soils into groups with similarbehavior, in terms of simple indices, can providebehavior, in terms of simple indices, can providegeotechnical engineers a general guidanceabout engineering properties of the soils throughthe accumulated experience.p

Communicate between

Engineers

Simple Indices

GSD LL PI

Classification System

(Language)

Estimate Engineering

ti

Achieve Engineering

Engineers

GSD, LL, PI (Language) properties purposes

Use the accumulated

i

52

experienceDr. H.B.NAGARAJ, Asst Prof in Civil Engineering


Requirements for a Soil Classification System

It should have a limited number ofgroups.

It should be based on theengineering properties, which are most

l t f th f hi h threlevant for the purpose for which theclassification has been made.

It should be simple and should useIt should be simple and should usethe terms, which are easilyunderstood.



Soil Classification Systems

1. Particle size classification2 Textural classification2. Textural classification3. Highway Research Board (HRB)

classification4. Unified Soil Classification 5. Indian Soil Classification



The size of individual particles has an

Particle Size Classification

The size of individual particles has animportant influence on the behaviourof soils.

It is a general practice to classify thesoils into four broad groups, namely,

• Gravel• Sand• Sand• Silt size, and• Clay size.



Clay size.

While classifying the fine grained soils on the basis

Silt size and Clay size

While classifying the fine-grained soils on the basis of particle size, it is a good practice to write silt size and clay size and not just silt and clay. In general usage, the term silt and clay are used to denote the soils that exhibit plasticity and cohesion over a wide range of water content. The soil with clay-size particles may not exhibit the properties y p y p passociated with clays. For eg. Rockflour has the particles of the size of the clay particles, but does not possess plasticity. It is classified as clay size and not just clay in the particleIt is classified as clay-size and not just clay in the particle size classification systems.



Particle Size Classification Cont’d

Classification based on particle size is of immense value in the case ofis of immense value in the case of coarse-grained soils rather than fine-grained soils because the behaviour gof such soils depends mainly on the particle size, whereas fine-grained

il d d th l ti itsoils depend on the plasticity characteristics.



Classification based on particle size is of immense

Particle Size Classification Cont’d

pvalue in the case of coarse-grained soils rather than fine-grained soils because the behaviour of such soils depends mainly on the particle size whereas fine-grained soilsmainly on the particle size, whereas fine-grained soils depend on the plasticity characteristics.

S f th l ifi ti t b d ti l iSome of the classification systems based on particle size alone are:1. U.S. Bureau of Soil and Public Road Administration

(PRA) System Classification2. International soil classification3 M I T System



3. M.I.T System4. Indian Standard Classification

U.S. Bureau of Soil and Public Road Administration (PRA) System Cl ifi ti

This is one of the earliest classification systems

Classification

This is one of the earliest classification systems developed in 1895 by the U.S. Bureau of soils.

mm

mm

mm

mm

mm

mm m

Cl SiltCoarseMediumFineVery

Fi

0.00

5 m

0.05

m

2.0

m

0.01

0 m

0.25

m

0.50

m

1.0

mm

Clay(Size)

Silt(Size)

Fine Gravel

GravelMediumFine

Sand



International soil classification

This system was proposed for general use at the y p p ginternational Soils Congress held at Washington in 1927.

This was known as the Swedish Classification system before it was adopted as International systembefore it was adopted as International system.

In this system, an additional term Mo (Majla) has been used for soil particles in the size range between sand and iltsilt



International soil classification

mm

mm mmm mm m mmm

mm

m m

Ult Cl

0.00

02

0.02

m

2.0

mm

0.06

m

0.05

m

0.2

mm

1.0

mm

F C F C F FC C VCM

0.00

6

0.00

2

0.1

m

0.5

mm

Ultra Clay(Colloids) Gravel

MO(Majla)Clay Silt Sand



Prof. G. Gilboy at Massachusetts Institute of Technology

M.I.T System

y gyin U.S.A developed MIT system of classification of soils.

In this system the soil is divided into four groups:In this system, the soil is divided into four groups:a. Gravel, particle size greater than 2 mmb. Sand, particle size between 0.06 mm to 2 mm

Silt i ti l i b t 0 002 t 0 06c. Silt size, particle size between 0.002 mm to 0.06 mmd. Clay size, particle size smaller than 0.002 mm (2 µm)



MIT soil classification

mm

mm mmm m mmm

Cl

0.00

02

0.02

m

2.0

mm

0.06

m

0.2

mm

0.6

mm

Fine Med Coarse Fine CoarseMed

0.00

6

Clay (Size)

(Colloids)Gravel

Silt (Size) Sand



I.S. Classification (IS: 1498-1970)

mm

mm mmm

m mmCl Silt

CoarseMed

0.00

2 m

0.07

5 m

300

m

0.42

5 m

2 m

m

20 m

m

80 m

m

Coarse FineFine4.

75 m

mClay(Size)

Silt(Size)

Cobble

GravelSand

Boulders



The visual appearance of a soil is

Textural Classification System

ppcalled its texture.

The texture depends upon the particle size shape of particles andparticle size, shape of particles and gradation of particles and gradation of particles.

Th l l ifi iThe textural classification incorporates only the particle size.

Here, the term texture is used to

Clay mineralogy and how it affects water holding and plasticity,

express the percentage of the three constituents of soils, namely, sand, silt and clay

holding and plasticity characteristics are not evaluated with this classification system



and clay. classification system

According to the textural classification system the

Textural Classification System Cont’d

According to the textural classification system, the percentages of sand (size 0.05 to 2.0 mm), silt (size 0.005 to 0.05 mm) and clay (size less than 0.005 mm) are plotted along the three sides of an equilateral triangle.

The equilateral triangle is divided into 10 zones, q g ,each zone gives a type of soil.

The soil can be classified by determining the zone in which it liesin which it lies.

A key is given that indicates the directions in which the lines are to be drawn to locate the point.



Textural Classification Chart (Adapted from U.S. Public Roads Administration)



To use the graph, take the known clay siltthe known clay, silt, and percentages of the sample and follow the colour- coded grid lines t th i t h thto the point where they intersect.

Where would a sample t i i t i icontaining containing

15 % clay, 70 % silt, and 15 % sand be located?




Another example. If a soil contains 30 % sand 20 % silt andP sand, 20 % silt and 50 % clay.The point (P) falls in the zone labeled clay. Therefore, the soil is classified as clay.



y


The textural classification system is useful for classifying soils consisting of different constituentsdifferent constituents.

The system assumes that the soil does not contain particles larger than 2-mm isize.

However, if the soil contains a certain percentage of soil particles larger than 2 p g p gmm, a correction is required in which the sum of the percentages of sand, silt and clay is increased to 100 %



clay is increased to 100 %.

The textural classification system is useful for classifying soils consisting of different constituents.

For e.g. if a soil contains 20 % particles of size larger than 2-mm size, the actual sum of the percentages of sand, silt and clay particles is 80 pe ce tages o sa d, s t a d c ay pa t c es s 80%.

Let these be respectively 12, 24, and 44 %. The corrected percentages would be obtained bycorrected percentages would be obtained by multiplying with a factor of 100/80.

Therefore, the corrected percentages are 15, 30 and 55 %.

The textural classification of the soil would be done based on these corrected percentages.



p g

THANK YOU



L1- Soil Classification 28-08-09

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