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DEEP DYNAMIC COMPACTIONDEEP DYNAMIC COMPACTION

Engr Sarfraz AliEngr Sarfraz Ali

sarfrazengr@yahoo.comsarfrazengr@yahoo.com

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IN THE NAME OF ALLAH, THE MOST BENEFICENT,

THE MOST MERCIFUL

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Methods for Soil ImprovementMethods for Soil ImprovementGround

Reinforcement

Ground

Improvement

Ground

Treatment

Stone Columns Soil Nails Deep Soil Nailing

Micropiles (Mini-piles) Jet Grouting Ground Anchors Geosynthetics

Fiber Reinforcement Lime Columns Vibro-Concrete

Column Mechanically

Stabilized Earth Biotechnical

Deep DynamicCompaction

Drainage/Surcharge

Electro-osmosis Compaction

grouting Blasting Surface

Compaction

Soil Cement Lime Admixtures Flyash

Dewatering Heating/Freezing Vitrification

Compaction

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Compaction and ObjectivesCompaction and Objectives

CompactionCompaction

ManyMany typestypes ofof earthearth construction,construction, suchsuch asas dams,dams, retainingretainingwalls,walls, highways,highways, andand airport,airport, requirerequire manman--placedplaced soil,soil, oror fillfill..ToTo compactcompact aa soil,soil, thatthat is,is, toto placeplace itit inin aa densedense statestate..

TheThe densedense statestate isis achievedachieved throughthrough thethe reductionreduction ofof thethe airairvoidsvoids inin thethe soil,soil, withwith littlelittle oror nono reductionreduction inin thethe waterwatercontentcontent.. ThisThis processprocess mustmust notnot bebe confusedconfused withwithconsolidation,consolidation, inin whichwhich waterwater isis squeezedsqueezed outout underunder thetheactionaction ofof aa continuouscontinuous staticstatic loadload..

Objectives:Objectives:

(1)(1) Decrease future settlementsDecrease future settlements

(2)(2) Increase shear strengthIncrease shear strength

(3)(3) Decrease permeabilityDecrease permeability

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Share information on:Share information on:

Experiences of dynamic compactionExperiences of dynamic compaction

TechniqueTechnique

DesignDesign

EvaluationEvaluation

EffectivenessEffectiveness

AimAim

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TechniqueTechnique

Energy transfer mechanismEnergy transfer mechanism

Stages of compactionStages of compactionApplicationApplication which soils are compacted ?which soils are compacted ?

TypesTypes

Ground VibrationsGround Vibrations

Design ConsiderationsDesign Considerations

QuestionsQuestions

SequenceSequence

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TECHNIQUETECHNIQUE

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TechniqueTechnique involvesinvolves repeatedlyrepeatedly droppingdropping aa largelarge weightweight

fromfrom aa cranecrane

WeightWeight maymay rangerange fromfrom 66 toto 172172 tonstons

DropDrop heightheight typicallytypically variesvaries fromfrom 1010 mm toto 4040 mm

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degreedegree ofof densificationdensification achievedachieved isis aa functionfunction ofof thethe

energyenergy inputinput (weight(weight andand dropdrop height)height) asas wellwell asas thethe

saturationsaturation level,level, finesfines contentcontent andand permeabilitypermeability ofof thethe

materialmaterial

66 3030 tonton weightweight cancan densifydensify thethe looseloose sandssands toto aa depthdepth

ofof 33 mm toto 1212 mm

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DoneDone systematicallysystematically inin aa rectangularrectangular oror triangulartriangular

patternpattern inin phasesphases

EachEach phasephase cancan havehave nono ofof passespasses;; primary,primary, secondary,secondary,tertiary,tertiary, etcetc..

3 m 3 m 3 m 3 m3 m3 m3 m 3 m 3 m 3 m3 m3 m

8 m

8m

LEGE D

Primary Pass

Secondary Pass

3 m 3 m 3 m 3 m3 m3 m3 m 3 m 3 m 3 m3 m3 m

8 m

8m

LEGE D

Primary Pass

Secondary Pass

(a)(b)

3 m 3 m 3 m 3 m3 m3 m3 m 3 m 3 m 3 m3 m3 m

8 m

8m

LEGE D

Primary Pass

Secondary Pass

3 m 3 m 3 m 3 m3 m3 m3 m 3 m 3 m 3 m3 m3 m

8 m

8m

LEGE D

Primary Pass

Secondary Pass

(a)(b)

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SpacingSpacing betweenbetween impactimpact pointspoints dependdepend uponupon::

DepthDepth ofof compressiblecompressible layerlayer

PermeabilityPermeability ofof soilsoil ocationocation ofof groundground waterwater levellevel

DeeperDeeper layerslayers areare compactedcompacted atat widerwider gridgrid

spacing,spacing, upperupper layerlayer areare compactedcompacted withwith closercloser

gridgrid spacingspacing

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DeepDeep craterscraters areare formedformed byby tampingtamping

CratersCraters maymay bebe filledfilled withwith sandsand afterafter eacheach passpass

HeaveHeave aroundaround craterscraters isis generallygenerally smallsmall

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ENER Y TRANSFER MECHANISMENER Y TRANSFER MECHANISM

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Energy transferred by propagation of RayleighEnergy transferred by propagation of Rayleigh

(surface) waves and volumic (shear and(surface) waves and volumic (shear and

compression) wavescompression) waves RayleighRayleigh 67 %67 %

ShearShear 26 %26 %

CompressionCompression 7%7%

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DENSIFICATION PROCESSDENSIFICATION PROCESS

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Compressibility of saturated soil due to presence ofCompressibility of saturated soil due to presence of

micro bubblesmicro bubbles

radual transition to liquefaction under repeatedradual transition to liquefaction under repeatedimpactsimpacts

Rapid dissipation of pore pressures due to highRapid dissipation of pore pressures due to high

permeability after soil fissuringpermeability after soil fissuring

Thixotropic recoveryThixotropic recovery

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APP ICATION

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Zone 1: Best

Zone 3: Worst (consider alternate methods)

Zone 2: Must apply multiple phases to allow for pore pressure dissipation

Zone 1: Best

Zone 3: Worst (consider alternate methods)

Zone 2: Must apply multiple phases to allow for pore pressure dissipation

Applicable to wide variety of soilsApplicable to wide variety of soils

rouping of soils on the basis of grain sizesrouping of soils on the basis of grain sizes

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Mainly used to compact granular fillsMainly used to compact granular fills

Particularly useful for compacting rockfills belowParticularly useful for compacting rockfills below

water and for bouldery soils where other methods canwater and for bouldery soils where other methods cannot be applied or are difficultnot be applied or are difficult

Waste dumps, sanitary landfills, and mine wastesWaste dumps, sanitary landfills, and mine wastes

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InIn sanitarysanitary fills,fills, settlementssettlements areare causedcaused eithereither byby

compressioncompression ofof voidsvoids oror decayingdecaying ofof thethe trashtrash materialmaterial

overover time,time, DDCDDC isis effectiveeffective inin reducingreducing thethe voidvoid ratio,ratio,andand thereforetherefore reducingreducing thethe immediateimmediate andand longlong termterm

settlementsettlement..

DDCDDC isis alsoalso effectiveeffective inin reducingreducing thethe decayingdecaying problem,problem,

sincesince collapsecollapse meansmeans lessless availableavailable oxygenoxygen forfor decayingdecayingprocessprocess..

ForFor recentrecent fillsfills wherewhere organicorganic decompositiondecomposition isis stillstill

underway,underway, DDCDDC increasesincreases thethe unitunit weightweight ofof thethe soilsoil

massmass byby collapsingcollapsing voidsvoids andand decreasingdecreasing thethe voidvoid ratioratio..

ForFor olderolder fillsfills wherewhere biologicalbiological decompositiondecomposition isis

complete,complete, DDCDDC hashas greatestgreatest effectseffects byby increasingincreasing unitunit

weightweight andand reducingreducing longlong termterm groundground subsidencesubsidence..

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TYPES

OF

DYNAMIC COMPACTION

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Dynamic compactionDynamic compaction

Dynamic consolidationDynamic consolidation

Dynamic replacementDynamic replacement

Rotational dynamic compactionRotational dynamic compaction

Rapid impact dynamic compactionRapid impact dynamic compaction

TYPES OF DYNAMIC COMPACTIONTYPES OF DYNAMIC COMPACTION

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ItIt isis thethe compactioncompaction ofof unsaturatedunsaturated oror highlyhighly

permeablepermeable saturatedsaturated granulargranular materialsmaterials byby heavyheavy

tampingtamping

TheThe responseresponse toto tampingtamping isis immediateimmediate

Dynamic CompactionDynamic Compaction

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TheThe improvementimprovement byby heavyheavy tampingtamping ofof saturatedsaturated

cohesivecohesive materialsmaterials inin whichwhich thethe responseresponse toto tampingtamping isis

largelylargely timetime dependentdependent

ExcessExcess porepore waterwater pressurespressures areare generatedgenerated asas aa resultresult

ofof tampingtamping andand dissipatedissipate overover severalseveral hourshours oror daysdays afterafter

tampingtamping..

Dynamic ConsolidationDynamic Consolidation

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TheThe formationformation byby heavyheavy tampingtamping ofof largelarge pillarspillars ofof importedimported

granulargranular soilsoil withinwithin thethe bodybody ofof softsoft saturatedsaturated soilsoil toto bebe improvedimproved

TheThe originaloriginal soilsoil isis highlyhighly compressedcompressed andand consolidatedconsolidated betweenbetween

thethe pillarspillars andand thethe excessexcess porepore pressurepressure generatedgenerated requiresrequires severalseveral

hourshours toto dissipatedissipate

TheThe pillarspillars areare usedused bothboth forfor soilsoil reinforcementreinforcement andand drainagedrainage

Dynamic ReplacementDynamic Replacement

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Process of Dynamic Replacement

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AA newnew dynamicdynamic compactioncompaction techniquetechnique whichwhich makesmakes useuse ofof thethefreefree fallfall energyenergy asas wellwell asas rotationalrotational energyenergy ofof thethe tampertamper calledcalled

RotationalRotational DynamicDynamic CompactionCompaction (RDC)(RDC)

TheThe techniquetechnique increasesincreases depthdepth ofof improvementimprovement inin granulargranularsoilssoils

ComparativeComparative studystudy showedshowed thatthat thethe conecone penetrationpenetration resistanceresistance

waswas generallygenerally largerlarger thanthan conventionalconventional dynamicdynamic compactioncompaction andand

thethe tampertamper penetrationpenetration inin rotationalrotational dynamicdynamic compactioncompaction waswas

twicetwice asas largelarge asas thatthat ofof conventionalconventional dynamicdynamic compactioncompaction

Rotational Dynamic CompactionRotational Dynamic Compaction

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Rotational Dynamic CompactionRotational Dynamic Compaction

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Rapid Impact Dynamic CompactionRapid Impact Dynamic Compaction

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EVA UATION

OF

IMPROVEMENT

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TheThe depthdepth ofof improvementimprovement isis proportionalproportional toto thethe energyenergy

perper blowblow

TheThe improvementimprovement cancan bebe estimatedestimated throughthrough empiricalempirical

correlation,correlation, atat designdesign stagestage andand isis verifiedverified afterafter

compactioncompaction throughthrough fieldfield teststests suchsuch asas StandardStandard

PenetrationPenetration TestsTests (SPT),(SPT), ConeCone PenetrationPenetration TestTest (CPT),(CPT),

etcetc..

EVA UATION OF IMPROVEMENTEVA UATION OF IMPROVEMENT

W

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DDmaxmax==nnW x HW x H

Where,Where,DDmaxmax == Max depth of improvement, mMax depth of improvement, m

nn == CoefficientCoefficient thatthat caterscaters forfor soilsoil andand

equipmentequipment variabilityvariability

WW == WeightWeight ofof tamper,tamper, tonstons

HH == Height of fall of tamper, mHeight of fall of tamper, m

TheThe effectivenesseffectiveness ofof dynamicdynamic compactioncompaction cancan alsoalso bebeassessedassessed readilyreadily byby thethe cratercrater depthdepth andand requirementrequirement ofof

backfillbackfill

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Reference N-Values

Menard and Broise (1975) 1.0

Leonard et al. (1980) 0.5Bjolgerud and Han (1963) 1.0 (rockfill)

Smoltcyk (1983)0.5 (soil with unstable structure)0.67 (silts and sands)

1.0 (purely frictional sand)Lukas (1980) 0.65 - 0.8

Mayne et al. (1984) 0.3 - 0.8

Gambin (1984) 0.5 1.0

Qian (1985) 0.65 (fine sand)0.66 (soft clay)0.55 (loess)

Van Impe (1989) 0.65 (silty sand)0.5 (clayey sand)

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GROUND VIBRATIONS

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DynamicDynamic compactioncompaction generatesgenerates surfacesurface waveswaves withwith aa

dominantdominant frequencyfrequency ofof 33 toto 1212 HzHz

TheseThese vibrationsvibrations generategenerate compression,compression, shearshear andand

RayleighRayleigh waveswaves

TheThe RaleighRaleigh waveswaves containcontain aboutabout 6767 percentpercent ofof thethe

totaltotal vibrationvibration energyenergy andand becomebecome predominantpredominant overover

otherother wavewave typestypes atat comparativelycomparatively smallsmall distancesdistances

fromfrom thethe sourcesource

RaleighRaleigh waveswaves havehave thethe largestlargest practicalpractical interestinterest forfor

thethe designdesign engineersengineers becausebecause buildingbuilding foundationsfoundations

areare placedplaced nearnear thethe groundground surfacesurface

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TheThe groundground vibrationsvibrations areare quantifiedquantified inin termsterms ofof

peakpeak particleparticle velocityvelocity (PPV)(PPV);; thethe maximummaximum velocityvelocity

recordedrecorded inin anyany ofof thethe threethree coordinatecoordinate axesaxes

TheThe measurementmeasurement ofof vibrationsvibrations isis necessarynecessary toto

determinedetermine anyany riskrisk toto nearbynearby structuresstructures

TheThe vibrationsvibrations cancan bebe estimatedestimated throughthrough empiricalempirical

correlationscorrelations oror measuredmeasured withwith thethe helphelp ofof

instrumentsinstruments suchsuch asas portableportable seismograph,seismograph,

accelerometers,accelerometers, velocityvelocity transducers,transducers, linearlinear variablevariable

displacementdisplacement transducerstransducers ( VDT),( VDT), etcetc..

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TheThe frequencyfrequency ofof thethe RaleighRaleigh waveswaves decreasesdecreases withwith

increasingincreasing distancedistance fromfrom thethe pointpoint ofof impactimpact

RelationshipRelationship betweenbetween PPVPPV andand inverseinverse scaledscaled

distancedistance isis shownshown graphicallygraphically (the(the inverseinverse scaledscaled

distancedistance isis thethe squaresquare rootroot ofof thethe compactioncompaction energy,energy,

divideddivided byby thethe distance,distance, dd fromfrom thethe impactimpact point)point)

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Tolerance imits for StructuresTolerance imits for Structures

British Standard 7385: Part 2British Standard 7385: Part 2--1993, lays down following1993, lays down followingsafety limits for various structures having different naturalsafety limits for various structures having different natural

frequencies:frequencies:

Reinforced or framed structures industrial and heavyReinforced or framed structures industrial and heavy

commercial buildings at 4 Hz and abovecommercial buildings at 4 Hz and above 50 mm/s50 mm/s

UnUn--reinforced or light framed structures residential or lightreinforced or light framed structures residential or light

commercial type buildings at 4 Hzcommercial type buildings at 4 Hz 15 Hz15 Hz

1515--20 mm/s20 mm/s

UnUn--reinforced or light framed residential or lightreinforced or light framed residential or light

commercial type buildings at 15 Hzcommercial type buildings at 15 Hz 40 Hz and above40 Hz and above

2020--50 mm/s50 mm/s

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Effect on HumansEffect on Humans

0.1 mm/sec0.1 mm/sec not noticeablenot noticeable

0.15 mm/sec0.15 mm/sec nearly not noticeablenearly not noticeable

0.35 mm/sec0.35 mm/sec seldom noticeableseldom noticeable

1.00 mm/sec1.00 mm/sec always noticeablealways noticeable

2.00 mm/sec2.00 mm/sec clearly noticeableclearly noticeable

6.00 mm/sec6.00 mm/sec strongly noticeablestrongly noticeable

14.00 mm/sec14.00 mm/sec very strongly noticeablevery strongly noticeable

17. mm/sec17. mm/sec severe noticeablesevere noticeable

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MONITORING ANDCONTRO

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DESIG

N AND ANA YSISCONSIDERATIONS

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Depth of improvement, dDepth of improvement, d

Impact energy, EImpact energy, E

Influence of cable dragInfluence of cable drag

Equipment limitationsEquipment limitations

Influence of tamper sizeInfluence of tamper size

Grid spacing, S

Grid spacing, S

Time delay between passesTime delay between passes

Soil conditionsSoil conditions

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Primary concernPrimary concern

DependsDepends onon::

SoilSoil conditionsconditions

EnergyEnergy perper dropdrop

ContactContact pressurepressure ofof tampertamper

Grid

Grid spacingspacing

NumberNumber ofof passespasses

TimeTime laglag betweenbetween passespasses

Depth of ImprovementDepth of Improvement

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WeightWeight ofof tampertamper timestimes thethe heightheight ofof dropdrop

MainMain parameterparameter inin determiningdetermining thethe depthdepth ofof

improvementimprovement

CanCan bebe calculatedcalculated fromfrom thethe equationequation

DDmaxmax== nnWW xx HH

(Free(Free fallingfalling ofof weights)weights)

Impact E nergy, EImpact E nergy, E

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CableCable attachedattached toto thethe tampertamper causescauses frictionfriction andand

reducesreduces velocityvelocity ofof tampertamper

FreeFree fallfall ofof tampertamper isis moremore efficientefficient

Influence of Cable DragInfluence of Cable Drag

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CraneCrane capacitycapacity

HeightHeight ofof dropdrop

MassMass ofof tampertamper

TamperTamper sizesize

Equipment limitationsEquipment limitations

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SignificantSignificant effecteffect onon depthdepth ofof improvementimprovement

FirstFirst passpass compactscompacts deepestdeepest layer,layer, shouldshould bebe equalequal

toto thethe compressiblecompressible layerlayer

SubsequentSubsequent passespasses compactcompact shallowershallower layers,layers, maymay

requirerequire lesserlesser energyenergy

IroningIroning passpass compactscompacts toptop layerlayer

Grid SpacingGrid Spacing

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AllowAllow porepore pressurespressures toto dissipatedissipate

PiezometersPiezometers cancan bebe installedinstalled toto monitormonitor dissipationdissipation

ofof porepore pressurespressures followingfollowing eacheach passpass

Time Delay between PassesTime Delay between Passes

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SignificantSignificant effecteffect onon depthdepth ofof improvementimprovement

FirstFirst passpass compactscompacts deepestdeepest layer,layer, shouldshould bebe equalequal

toto thethe compressiblecompressible layerlayer

SubsequentSubsequent passespasses compactcompact shallowershallower layers,layers, maymay

requirerequire lesserlesser energyenergy

IroningIroning passpass compactscompacts toptop layerlayer

Grid SpacingGrid Spacing

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