soilcompaction.pptx

8/15/2019 SoilCompaction.pptx

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Soil Mechanics

−

Soil CompactionVIJAY BHILWADEIIT [email protected]

Outline

1. Soil Improvement

2. Compaction

3. Theory of Compaction

4. Properties and Structure of Compacted Fine-

rained Soils

!. Field Compaction "#uipment and Procedures

$. Field Compaction Control and Specifications


2/30

Soil Improvement

Methods for Soil Improvementround

%einforcement

& Stone Columns

& Soil 'ails

& (eep Soil 'ailin)

& *icropiles +*ini-piles,

& et routin)

& round nchors

& eosynthetics

& Fi/er %einforcement

& 0ime Columns

& i/ro-Concrete Column

& *echanically Sta/ilied

"arth

& iotechnical

round

Improvement

& (eep (ynamic

Compaction

& (raina)eSurchar)e

& "lectro-osmosis

& Compaction )routin)

& lastin)

& Surface Compaction

Compaction

round

Treatment

& Soil Cement

& 0ime dmi5tures

& Flyash

& (e6aterin)

& 7eatin)Freein)

& itrification

Shaefer8 199:

Soil Improvement

Methods for Soil Improvement- Jet Grouting

Courtesy of *enard-soltraitement


3/30

Soil Improvement

Methods for Soil Improvement-Soil Nailing

Courtesy of tlas Copco %oc;

(rillin) "#uipment

Soil Improvement

Elephant and Compaction

I?m smart.

The compaction result is

not )ood. @hy=

7eavy @ei)ht


4/30

Compaction

Compaction and Objectives

Compaction

*any types of earth construction8 such as dams8 retainin) 6alls8 hi)h6ays8and airport8 re#uire man-placed soil8 or fill. To compact a soil8 that is8 to place

it in a dense state.

The dense state is achieved throu)h the reduction of the air voids in the soil8

6ith little or no reduction in the 6ater content. This process must not /e

confused 6ith consolidation8 in 6hich 6ater is s#ueeed out under the action

of a continuous static load.

A/Bectives& (ecrease future settlements

& Increase shear stren)th

& (ecrease permea/ility+From 0am/e8 1991D 7ead8 1992,

Compaction

General Compaction MethodsCoarse-grained soils Fine-grained soils

&i/ratin) hammer +S, &Fallin) 6ei)ht and hammers

&Eneadin) compactors

&Static loadin) and press

&7and-operated vi/ration plates

&*otoried vi/ratory rollers

&%u//er-tired e#uipment

&Free-fallin) 6ei)htD dynamic

compaction +lo6 fre#uencyvi/ration8 41G 7,

Vibration

&7and-operated tampers

&Sheepsfoot rollers

&%u//er-tired rollers

Kneading+7olt and Eovacs8 19H1D 7ead8 1992,


5/30

heor! of Compaction

"aborator! CompactionAri)in

The fundamentals of compaction of fine-)rained soils are relatively ne6.

%.%. Proctor in the early 193G?s 6as /uildin) dams for the old ureau of @ater6or;s and Supply in 0os n)eles8 and he developed the principles

of compaction in a series of articles in "n)ineerin) 'e6s-%ecord. In his

honor8 the standard la/oratory compaction test 6hich he developed is

commonly called the proctor test .Purpose

The purpose of a la/oratory compaction test is to determine the proper amount of mixing water to use 6hen compactin) the soil in the field andthe resulting degree of denseness 6hich can /e e5pected from compactionat this optimum 6ater

Impact compactionThe proctor test is an impact compaction. hammer is dropped severaltimes on a soil sample in a mold. The mass of the hammer8 hei)ht of drop8

num/er of drops8 num/er of layers of soil8 and the volume of the mold are

specified.

heor! of Compaction

est E#uipmentStandard Proctor test e#uipment

(as8 199H


6/30

heor! of Compaction

Standard $roctor Compaction est

Summary of Standard Proctor Compaction Test

Specifications +ST* (-$9H8 S7TA,

(as8 199H

heor! of Compaction

Modified $roctor Compaction est

Summary of Modied Proctor Compaction TestSpecifications +ST* (-$9H8 S7TA,

(as8 199H


7/30

heor! of Compaction

Comparison-Summar!

Standard Proctor Test

12 in hei)ht of drop

!.! l/ hammer

2! /lo6slayer

3 layers

*old sie 13G ft3

"ner)y 1283:! ftl/ft3

*odified Proctor Test

1H in hei)ht of drop

1G l/ hammer

2! /lo6slayer

! layers

*old sie 13G ft3

"ner)y !$82!G ftl/ft3

Higher compacting energy

heor! of Compaction

Comparison-%h!&

& In the early days of compaction8 /ecause construction e#uipment 6as small

and )ave relatively lo6 compaction densities8 a la/oratory method that used

a small amount of compactin) ener)y 6as re#uired. s construction

e#uipment and procedures 6ere developed 6hich )ave hi)her densities8 it /ecame necessary to increase the amount of compactin) ener)y in the

la/oratory test.

& The modified test 6as developed durin) @orld @ar II /y the J.S. rmy

Corps of "n)ineerin) to /etter represent the compaction re#uired for airfield

to support heavy aircraft. The point is that increasin) the compactive effort

tends to increase the ma5imum dry density8 as e5pected8 /ut also decrease

the optimum 6ater content.

+7olt and Eovacs8 19H1D 0am/e8 1991,


8/30

heor! of Compaction

'ariables of CompactionProctor esta/lished that compaction is a function of four varia/les

+1,(ry density +ρd, or dry unit 6ei)ht γd.

+2,@ater content 6

+3,Compactive effort +ener)y ",

+4,Soil type +)radation8 presence of clay minerals8 etc.,

For standard

Proctor test

@ei)ht of

hammer

" K

7ei)ht of 'um/er of

× drop of × /lo6s per hammer layer

olume of mold

'um/er of ×layers

"=2.49!;)+9.H1m s2,+G.3G4Hm,+3 layers,+2!/lo6s layer,

−3 3G.944×1G m

3 3=!92.: ; m +1283:!ft⋅l/ ft ,

heor! of Compaction

$rocedures and (esults Procedures

+1, Several samples of the same soil8 /ut at different 6ater contents8 are

compacted accordin) to the compaction test specifications.

The first four /lo6sThe successive /lo6s

+2, The total or 6et density and the actual 6ater content of each

compacted sample are measured.

* ρρ= t 8ρd= (erive ρd from the ;no6n ρ

t 1+6 and 6

+3, Plot the dry densities ρdd versus 6ater contents 6 for each compacted

sample. The curve is called as a compaction curve.


9/30

heor! of Compaction

$rocedures and (esults )Cont*+%esults

Pea point

!ine of optimum

"ero air void

0ine of Lero air

optimums void

ρd ma5

*odified

Proctor

StandardProctor

6opt@ater content 6 +M, 7olt and Eovacs8 19H1

heor! of Compaction

$rocedures and (esults )Cont*+The pea; point of the compaction curve

The pea; point of the compaction curve is the point 6ith the ma5imum

dry density ρd ma5d ma5. Correspondin) to the ma5imum dry density ρd ma5 is a

6ater content ;no6n as the optimum 6ater content 6optopt +also ;no6n asthe optimum moisture content8 A*C,. 'ote that the ma5imum dry density

is only a ma5imum for a specific compactive effort and method of

compaction. This does not necessarily reflect the ma5imum dry density

that can /e o/tained in the field.

Lero air voids curve

The curve represents the fully saturated condition +S K 1GG M,. +#t cannot be reached by compaction,

0ine of optimums line dra6n throu)h the pea; points of several compaction curves at

different compactive efforts for the same soil 6ill /e almost parallel to a

1GG M S curve8 it is called the line of optimums


10/30

heor! of Compaction

$rocedures and (esults )Cont*+

The "#uation for the

curves 6ith different

de)ree of saturation is

ρd=

6

ρ6S

ρ6+

=

S

ρ6

6+

S

S

ρ s s

Nou can derive the e#uation

/y yourself

ρs7int ρ =

d

1+eSe= 6s

7olt and Eovacs8 19H1

heor! of Compaction

$rocedures and (esults-E,planation

elo6 6opt +dry side of optimum,

s the 6ater content increases8 the particles

develop lar)er and lar)er 6ater films around

them8 6hich tend to Olu/ricate the particlesand ma;e them easier to /e moved a/out and

reoriented into a denser confi)uration.

t 6opt

The density is at the ma5imum8 and it does

not increase any further.

/ove 6opt +6et side of optimum,

@ater starts to replace soil particles in themold8 and since ρ6 QQ ρs the dry density

starts to decrease.

!ubrication or loss of suction$$

+6opt8 ρd ma5,

ρd

6



11/30

heor! of Compaction

$rocedures and (esults-Notes

"ach data point on the curve represents a sin)le compaction

test8 and usually four or five individual compaction tests arere#uired to completely determine the compaction curve.

t least t6o specimens 6et and t6o specimens dry of

optimum8 and 6ater contents varyin) /y a/out 2M.

Aptimum 6ater content is typically sli)htly less than the

plastic limit +ST* su))estion,. Typical values of ma5imum dry density are around 1.$ to 2.G

*)m3 6ith the ma5imum ran)e from a/out 1.3 to 2.4 *)m3.

Typical optimum 6ater contents are /et6een 1GM and 2GM86ith an outside ma5imum ran)e of a/out !M to 4GM.


heor! of Compaction

Effects of Soil !pes on Compaction

The soil type-that is8 )rain-sie distri/ution8 shape of the soil )rains8

specific )ravity of soil solids8 and amount and type of clay minerals

present.

7olt and Eovacs8 19H1D (as8 199H


12/30

Structure of Compacted Cla!s

Structure of Compacted Cla!s

& For a )iven compactive

effort and dry density8 thesoil tends to /e more

flocculated +random, for

compaction on the dry side

as compared on the 6et side.

& For a )iven moldin) 6ater content8 increasin) the

compactive effort tends to

disperse+parallel8 oriented,

the soil8 especially on the

dry side.

0am/e and @hitman8 19:9

Engineering $roperties-$ermeabilit!

& Increasin) the 6ater contentresults in a decrease in

permea/ility on the dry side of

the optimum moisture contentand a sli)ht increase in

permea/ility on the 6et side of

optimum.

& Increasin) the compactive effort

reduces the permea/ility since it

/oth increases the dry density8

there/y reducin) the voids

availa/le for flo68 and increasesthe orientation of particles.

From 0am/e and @hitman8 19:9D



13/30

Engineering $roperties-Compressibilit!

t lo6 stresses the sample compacted on the 6et side is

more compressi/le than the one compacted on the dry side.



Engineering $roperties-Compressibilit!

t the hi)h applied stresses the sample compacted on the dry side

is more compressi/le than the sample compacted on the 6et side.




14/30

Engineering $roperties-Selling

S6ellin) of compacted clays is )reater for those

compacted dry of optimum. They have a relatively)reater deficiency of 6ater and therefore have a

)reater tendency to adsor/ 6ater and thus s6ell more.

7i)her

s6ellin)

potential ρd

+6opt8 ρd ma5,7i)her shrin;a)e

potential

6

From 7olt and Eovacs8 19H1

Engineering $roperties-StrengthSamples +Eaolinite,compacted dry of

optimum tend to /e

more ri)id and

stron)er than

samples compacted

6et of optimum

From 0am/e and

@hitman8 19:9


15/30

The C% +California /earin) ratio,

C%K the ratio /et6een resistance re#uiredto penetrate a 3-in2 piston into the

compacted specimen and resistancere#uired to penetrate the same depth into a

standard sample of crushed stone.

)reater compactive effort produces a

)reater C% for the dry of optimum.7o6ever8 the C% is actually less for

the 6et of optimum for the hi)her

compaction ener)ies +overcompaction,.


Engineering $roperties-Summar!

Structure

Permea/ility

Compressi/ility

S6ellin)

Stren)th

(ry side

*ore random

*ore permea/le

*ore compressi/le in

high pressure ran)e

S6ell more8

hi)her 6ater

deficiency

7i)her

@et side

*ore oriented

+parallel,

*ore compressi/le in

low pressure ran)e

RShrin; more


16/30

Engineering $roperties-Notes

"n)ineers must consider not only the /ehavior of the soil as

compacted /ut the /ehavior of the soil in the completed structure8

especially at the time 6hen the sta/ility or deformation of the

structure is most critical.

For e5ample8 consider an element of compacted soil in a dam core.

s the hei)ht of the dam increases8 the total stresses on the soil

element increase. @hen the dam is performin) its intended

function of retainin) 6ater8 the percent saturation of the compacted

soil element is increased /y the permeatin) 6ater. Thus the

en)ineer desi)nin) the earth dam must consider not only the

stren)th and compressi/ility of the soil element as compacted8 /ut

also its properties after is has /een su/Bected to increased total

stresses and saturated /y permeatin) 6ater.0am/e and @hitman8 19:9

.ield E#uipment and $rocedure

E#uipment

Smooth-6heel roller +drum, & 1GGM covera)e under the 6heel

& Contact pressure up to 3HG ;Pa

& Can /e used on all soil types

e5cept for roc;y soils.

& Compactive effort static 6ei)ht

& The most common use of lar)e

smooth 6heel rollers is for proof-

rollin) su/)rades and compactin)

asphalt pavement.



17/30


E#uipment )Cont*+

Pneumatic +or ru//er-tired, roller & HGM covera)e under the 6heel

& Contact pressure up to :GG ;Pa

& Can /e used for /oth )ranular and

fine-)rained soils.


and ;neadin).

& Can /e used for hi)h6ay fills or

earth dam construction.



E#uipment )Cont*+

Sheepsfoot rollers & 7as many round or rectan)ular shaped protrusions or Ofeet

attached to a steel drum

& HM 12 M covera)e

& Contact pressure is from 14GG to

:GGG ;Pa

& It is /est suited for clayed soils.


and ;neadin).



18/30


E#uipment )Cont*+

Tampin) foot roller & /out 4GM covera)e


H4GG ;Pa

& It is /est for compactin) fine-

)rained soils +silt and clay,.


and ;neadin).



E#uipment )Cont*+

*esh +or )rid pattern, roller & !GM covera)e


$2GG ;Pa

& It is ideally suited for compactin)

roc;y soils8 )ravels8 and sands.

@ith hi)h to6in) speed8 the

material is vi/rated8 crushed8 and

impacted.


and vi/ration.



19/30


E#uipment )Cont*+

i/ratin) drum on smooth-6heel

roller

& ertical vi/rator attached to

smooth 6heel rollers.

& The /est e5planation of 6hy roller

vi/ration causes densification of

)ranular soils is that particle

rearran)ement occurs due to cyclic

deformation of the soil produced

/y the oscillations of the roller.


and vi/ration.

& Suita/le for )ranular soils



E#uipment-Summar!



20/30


'ariables-'ibrator! CompactionThere are many varia/les 6hich control the vi/ratory

compaction or densification of soils.

Characteristics of the compactor:+1, *ass8 sie

+2, Aperatin) fre#uency and fre#uency ran)e

Characteristics of the soil:+1, Initial density

+2, rain sie and shape

+3, @ater content

Construction procedures:+1, 'um/er of passes of the roller

+2, 0ift thic;ness

+3, Fre#uency of operation vi/rator

+4, To6in) speed7olt and Eovacs8 19H1


.re#uenc!

The fre#uency at 6hich

a ma5imum density is

achieved is called the

optimum fre#uency.



21/30


(oller ravel Speed

For a )iven num/er of passes8a hi)her density is o/tained if

the vi/rator is to6ed more

slo6ly.



(oller $asses

@hen compactin) past five or so

covera)es8 there is

not a )reat increasein density

&24G cm thin; layer

of northern Indiana

dune sand

&!$:G ;) roller

operatin) at a

fre#uency of 2:.! 7.



22/30


/etermine the "ift 0eight



/!namic Compaction

(ynamic compaction 6as first used in

ermany in the mid-193G?s.

The depth of influence (8 in meters8 of soilunder)oin) compaction is conservatively

)iven /y

( ≈ +@h,12

@ K mass of fallin) 6ei)ht in metric tons.

h K drop hei)ht in meters



23/30


'ibroflotation

i/roflotation is a techni#ue for

in situ densification of thic;

layers of loose )ranular soil

deposits. It 6as developed in

ermany in the 193Gs.

From (as8 199H

'ibroflotation-$rocedures

From (as8 199H

Stage1 The Bet at the /ottom of the i/roflot is turned on and lo6ered into the )round

Stage2 The 6ater Bet creates a #uic; condition in the soil. It allo6s the vi/ratin) unit tosin; into the )round

Stage 3 ranular material is poured from the top of the hole. The 6ater from the lo6er Bet

is transferred to he Bet at the top of the vi/ratin) unit. This 6ater carries the )ranular material do6n the hole

Stage 4 The vi/ratin) unit is )radually raised in a/out G.3-m lifts and held vi/ratin) for a/out 3G seconds at each lift. This process compacts the soil to the desired unit 6ei)ht.


24/30

.ield Control and Specification

Control $arameters

%ry density and water content correlate 6ell 6ith the

en)ineerin) properties8 and thus they are convenientconstruction control parameters.

Since the o/Bective of compaction is to sta/ilie soils

and improve their en)ineerin) /ehavior8 it is important

to ;eep in mind the desired en)ineerin) properties of

the fill8 not Bust its dry density and 6ater content. This point is often lost in the earth6or; construction

control.



/esign-Construct $rocedures

0a/oratory tests are conducted on samples of the

proposed /orro6 materials to define the properties

re#uired for desi)n. fter the earth structure is desi)ned8 the compaction

specifications are 6ritten. Field compaction controltests are specified8 and the results of these /ecome thestandard for controllin) the proBect.



25/30


Specifications

+1, "nd-product specifications

This specification is used for most hi)h6ays and /uildin)foundation8 as lon) as the contractor is a/le to o/tain the

specified relative compaction 8 ho6 he o/tains it doesn?t matter8nor does the e#uipment he uses.

Care the results only &

+2, *ethod specifications

The type and 6ei)ht of roller8 the num/er of passes of that roller8

as 6ell as the lift thic;ness are specified. ma5imum allo6a/lesie of material may also /e specified.

#t is typically used for large compaction pro'ect(



(elative Compaction )(*C*+

%elative compaction or percent compaction

ρ

%.C.=ρ

d−filed

×1GGMd ma5−la/oratory

Correlation /et6een relative compaction

+%.C., and the relative density (r

It is a statistical result%.C. = HG+G.2(r /ased on 4: soil

samples.

s (r K G8 %.C. is HG

)ypical re*uired +(C( , -./ 0 -1/


26/30


/etermine the %ater Content )in .ield+

Control

0ine of

optimums

ρd ma5

9GM %.C.

1

1GGM saturation

+1, %elative compaction

+2, @ater content +dry side

or 6et side,

2

3

a

Increase

compaction

ener)y

6opt@ater content 6 M

/ c

'ote the en)ineerin)

properties may /e different

/et6een the compacted

sample at the dry side and at

the 6et side.7olt and Eovacs8 19H1


/etermine the (elative Compaction in the .ield

Where and WhenFirst8 the test site is selected. It should /e representative or

typical of the compacted lift and /orro6 material. Typical

specifications call for a ne6 field test for every 1GGG to 3GGGm2 or so8 or 6hen the /orro6 material chan)es si)nificantly.

It is also advisa/le to ma;e the field test at least one or

may/e t6o compacted lifts /elo6 the already compacted

)round surface8 especially 6hen sheepsfoot rollers are used

or in )ranular soils.

Method

Field control tests8 measurin) the dry density and 6ater content in the field can either /e destructive or

nondestructive.7olt and Eovacs8 19H1


27/30


/estructive

Methods

Methods

+a, Sand cone+/, alloon

+c, Ail +or 6ater, method

Calculations&Eno6 *s and t

&et ρd field and 6 +6ater content,

&Compare ρd field 6ith ρd ma5-la/

and calculate relative compaction%.C.

+a,

+/,

+c,



/estructive Methods )Cont*+

Sometimes8 the la/oratory ma5imum density may not

/e ;no6n e5actly. It is not uncommon8 especially in

hi)h6ay construction8 for a series of la/oratorycompaction tests to /e conducted on Orepresentative

samples of the /orro6 materials for the hi)h6ay. If the

soils at the site are hi)hly varied8 there 6ill /e no

la/oratory results to /e compared 6ith. It is time

consumin) and e5pensive to conduct a ne6 compaction

curve. The alternative is to implement a feld check point 8 or 1 point Proctor test.



28/30


/estructive Methods )Cont*+

Check Point M

&1 point Proctor test

& Eno6n compaction

curves 8 8 C

& Field chec; point

+it should /e on the

dry side of optimum,

0ine of

optimums

ρd ma5

*

C

1GGM saturation

N+no,

6opt 7olt and Eovacs8 19H1@ater content 6 M


/estructive Methods )Cont*+The measurin) error is mainly from the determination of the

volume of the e5cavated material.

For e5ample8 For the sand cone method8 the vi/ration from near/y 6or;in)

e#uipment 6ill increase the density of the sand in the hole8 6hich 6ill)ives a lar)er hole volume and a lo6er field density.

ρd−field=* s t

If the compacted fill is )ravel or contains lar)e )ravel particles. ny

;ind of unevenness in the 6alls of the hole causes a si)nificant error in

the /alloon method.

If the soil is coarse sand or )ravel8 none of the li#uid methods 6or;s6ell8 unless the hole is very lar)e and a polyethylene sheet is used to

contain the 6ater or oil.



29/30


Nondestructive Methods

uclear densit! meter+a, (irect transmission

+/, ac;scatter +c, ir )ap

Principles(ensity

The amma radiation is scattered /y the soil

particles and the amount of scatter is

proportional to the total density of the material.

The amma radiation is typically provided /y

the radium or a radioactive isotope of cesium.@ater content

The 6ater content can /e determined /ased on

the neutron scatter /y hydro)en atoms. Typical

neutron sources are americium-/eryllium

isotopes.

+a,

+/,


+c,


Nondestructive Methods )Cont*+

Cali"ration

Cali/ration a)ainst compacted materials of ;no6n

density is necessary8 and for instruments operatin) onthe surface8 the presence of an uncontrolled air )ap can

si)nificantly affect the measurements.


30/30

(eferencesMain #eferences:

7olt8 %.(. and Eovacs8 @.(. +19H1,. 2n #ntroduction to

3eotechnical 4ngineering8 Prentice 7all. +Chapter !, $thers:

(as8 .*. +199H,. Principles of 3eotechnical 4ngineering8 4thedition8 P@S Pu/lishin) Company.

0am/e8 T.@. and @hitman8 %.. +19:9,. Soil Mechanics8 SI ersion8

ohn @iley U Sons.

Schaefer8 . %. +199:,. 3round #mprovement5 3round +einforcement53round )reatment 8 Proceedin)s of Soil Improvement and

eosynthetics of The eo-Institute of the merican Society of Civil

"n)ineers in conBunction 6ith eo-0o)an?9:. "dited /y .%.

Schaefer.

soilcompaction.pptx

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