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Static Testing Static Testing Expensive Expensive Time consuming Time consuming
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Odot- Pda Intro

Jul 21, 2016

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Page 1: Odot- Pda Intro

Static TestingStatic Testing••ExpensiveExpensive

••Time consumingTime consuming

Page 2: Odot- Pda Intro

Dynamic Pile Testingwith the

Pile Driving Analyzer ®

Dynamic Pile Testingwith the

Pile Driving Analyzer ®

© 2002, Pile Dynamics, © 2002, Pile Dynamics, IncInc..Quality Assurance for Deep FoundationsQuality Assurance for Deep Foundations

Page 3: Odot- Pda Intro

DYNAMIC TESTING

• Research began at Case Institute of Technology (Cleveland) in 1964 under G. Goble

• Developed “Case Method” – “PDA”– Pile capacity from pile top measurements

• WEAP (Wave Equation Analysis Program)

• CAPWAP (CAse Pile Wave Analysis Program

Page 4: Odot- Pda Intro

DYNAMIC METHODS

• Do not hinder pile driving• Are much less expensive than static tests• Can test many piles (a representative

sample)

Page 5: Odot- Pda Intro

Case Method – PDA• CONSTRUCTION CONTROL

– Test sample of production piles to insure capacity over entire project.

• DESIGN– Can be cost effective to test for pile capacity as a

function of penetration• Lower penetration to reach design capacity.

• REPLACE OR SUPPLEMENT STATIC TESTS– For large capacity piles– Offshore environments

Page 6: Odot- Pda Intro

Case Method – PDA

• RESULTS– Hammer performance

• Compute transferred energy, efficiency• Monitor effects of changes in hammer cushion, helmet and pile

cushion

– Pile stresses• Compressive (hard driving)• Tensile (easy driving)

– Pile integrity– Pile capacity

Page 7: Odot- Pda Intro

GRLWEAP• INPUT

– Hammer properties– Hammer and pile cushion properties– Helmet weight– Pile Properties– Soil Properties

• Quakes, damping, resistance distribution

• OUTPUT– Resistance vs. blow count– Stresses vs. pile length/blow count– Transferred hammer energy

Page 8: Odot- Pda Intro

CAPWAP

• PROCEDURE:1. Input soil model (quakes, damping, etc.)2. Use measured velocity as input3. Compute pile top force4. Compare computed force to measured force5. Modify soil model as necessary until field and

measured force are in agreement

Page 9: Odot- Pda Intro

CAPWAP

• OUTPUT:1. Ultimate capacity and distribution2. Stresses vs. pile length3. Quakes4. Damping factors Used to refine

GRLWEAP

Page 10: Odot- Pda Intro

Dynamic Testing BenefitsDynamic Testing BenefitsDynamic Testing Benefits

•• More information in less time (reduces delays):More information in less time (reduces delays):•• Confirms pile capacity design Confirms pile capacity design

•• EvaluatesEvaluates integrity, stresses, hammer energyintegrity, stresses, hammer energy

•• Improves quality control Improves quality control

••(test more piles; tests “problem piles”)(test more piles; tests “problem piles”)

•• Rational means to reduce pile costsRational means to reduce pile costs•• shorter piles or fewer piles (lower S.F.)shorter piles or fewer piles (lower S.F.)

•• Significantly less cost than static testSignificantly less cost than static test

Page 11: Odot- Pda Intro

CaseCase MethodMethod1958: first thesis 1958: first thesis

1964: field testing began under 1964: field testing began under direction ofdirection of DrDr. G.G. . G.G. GobleGoble

W

measure measure

Compute from measurementsCompute from measurements

•• hammer performance hammer performance

•• driving stressesdriving stresses

•• pile integrity pile integrity

•• capacitycapacity

“Monitoring”

“Dynamic Load testing”

Page 12: Odot- Pda Intro

Motion is measured Motion is measured by accelerometersby accelerometers

strainstraingagegage FF(t)(t)

accelerometeraccelerometer

vv(t)(t)

Dynamic Pile TestingDynamic Pile TestingDynamic Pile Testing

Load is appliedLoad is appliedby impacting ramby impacting ram

Load is measured byLoad is measured bystrain transducersstrain transducers

Page 13: Odot- Pda Intro

Strain Strain transducertransducer

AccelerometerAccelerometer

STRAIN

ACCELERATION

Page 14: Odot- Pda Intro

PDA testingdata acquisition

PDA testingdata acquisition

Page 15: Odot- Pda Intro

“PDA”“PDA”“PDA”

Pile Driving Analyzer ®

Page 16: Odot- Pda Intro

Hammer PerformanceHammer Performance

Why is it important?Why is it important?•• Contractor productivityContractor productivity

•• Sufficient for pile installationSufficient for pile installation to to designdesign depth and/or to required depth and/or to required capacitycapacity

Energy = ∫ Fv (dt)

Page 17: Odot- Pda Intro

Efficiency = Efficiency = Em / ErEm / ErEm = Measured Transf. EnergyEm = Measured Transf. EnergyEr = Rated EnergyEr = Rated Energy

0%0% 20%20% 40%40% 60%60% 80%80% 100%100%

20%20% 80%80%cabled drop hammerscabled drop hammers

60%60%30%30% diesel hammersdiesel hammers

40%40% 70%70%air or steam hammersair or steam hammers

60%60% 100%100%hydraulic drop hammershydraulic drop hammers

Efficiencies on concrete piles are lower ~ 10%Efficiencies on concrete piles are lower ~ 10%

Page 18: Odot- Pda Intro

Hammer performance and Hammer performance and cushion evaluation cushion evaluation

Page 19: Odot- Pda Intro
Page 20: Odot- Pda Intro

Driving StressesDrivingDriving StressesStressesKnowing stresses leads to steps to reduce risk of pile damage due to:

• Compression stress

• at both Top and Bottom

• Tension stress (concrete piles)

• Bending, Alignment

Knowing stresses leads to steps to Knowing stresses leads to steps to reduce risk ofreduce risk of pile damage due to:pile damage due to:

•• Compression stressCompression stress

•• at both Top and Bottomat both Top and Bottom

•• Tension stressTension stress (concrete piles)(concrete piles)

•• Bending, AlignmentBending, Alignment

Page 21: Odot- Pda Intro

PDA testingdata acquisition

PDA testingdata acquisition

Average force is proportional Average force is proportional and reasonable; 2 sensors can and reasonable; 2 sensors can

compensate large bendingcompensate large bending

Page 22: Odot- Pda Intro

Codes:Codes: Allowable Driving StressesAllowable Driving Stresses

USA - AASHTOSteel piles

90% of yield strength for steel

Concrete pilesCompression: (85% of c.strength) - prestressTension (PS): prestress + (50% of t.strength)

Compression: 85% of c.strengthTension (RR): 70% of yield of reinforcement

Page 23: Odot- Pda Intro
Page 24: Odot- Pda Intro
Page 25: Odot- Pda Intro

Pile integrityProblem:

Broken piles have low capacity

Detect damage by:

• blow count record , or very long piles

• visually (above ground, closed pipes)

• extraction

• Electronically ( PDA or PIT )

• or static load test

PilePile integrityintegrityProblem: Problem:

Broken piles have low capacityBroken piles have low capacity

Detect damage by:Detect damage by:

•• blow count record , or very long pilesblow count record , or very long piles

•• visually (above ground, closed pipes)visually (above ground, closed pipes)

•• extractionextraction

•• Electronically ( PDA or PIT )Electronically ( PDA or PIT )

•• or static load testor static load test

Page 26: Odot- Pda Intro

IntegrityIntegrityIntegrity•• Magnitude of damageMagnitude of damage•• LocationLocation

Page 27: Odot- Pda Intro
Page 28: Odot- Pda Intro

Normal time return (pile length OK)

Small damage

blow1

2

3

4

Integrity by PDA dynamic testing

Early return indicates shorter pile length

Large damage

Page 29: Odot- Pda Intro

Small damage

Large damage

blow

1

2

3

4

toetop

New toepile shorter

Page 30: Odot- Pda Intro
Page 31: Odot- Pda Intro

Start of damageStart of damage

Major damageMajor damagePile failed at pickup point. Pile failed at pickup point. Due to early handling, or Due to early handling, or low concrete strength, or low concrete strength, or

uneven toe stress (uneven toe stress (limerocklimerock))

Extraction reveals Extraction reveals damagedamage

12001200 psi prestresspsi prestress5000 5000 psi f’c psi f’c driven at 7 daysdriven at 7 days

Page 32: Odot- Pda Intro

β Condition100100 UniformUniform

80 80 -- 100100 Slight damageSlight damage60 60 -- 8080 Significant damageSignificant damage

<60<60 BrokenBroken

BETA guidelinesBETA guidelines

Capacity of broken piles Capacity of broken piles is meaninglessis meaningless

Page 33: Odot- Pda Intro

CapacityCapacity• At time of testing• vs depth during drive• resistance distribution

– CAPWAP ®

•• At time of testingAt time of testing•• vsvs depth during drivedepth during drive•• resistance distributionresistance distribution

–– CAPWAP CAPWAP ®®

Page 34: Odot- Pda Intro

PDA testingPDA testingdata interpretationdata interpretation

Easy drivingEasy driving Hard drivingHard driving

Page 35: Odot- Pda Intro

Pile as it encounters rock

Toe reflection in tension

(relatively easy driving)

Toe reflection in compression

(relatively hard driving)

Page 36: Odot- Pda Intro

End of Drive

Restrike (8 days)

Low shaft resistance

Increased shaft resistance

(setup)

Page 37: Odot- Pda Intro

PDA testingPDA testingdata interpretationdata interpretation

EOD 85 tonEOD 85 ton

BOR 1D BOR 1D -- 189 ton189 ton

BOR 75D BOR 75D -- 286 ton286 ton

Page 38: Odot- Pda Intro

Restrike testing -fine grained soilsRestrike testing -fine grained soils

log timelog time

capa

city

capa

city

1 da

y1

day

10 d

ays

10 d

ays

100

days

100

days

1000

day

s10

00 d

ays

Technically desirable

Technically desirableEconomically desirable

Economically desirable

Restrike testing generally underRestrike testing generally under--taken 1 to 10 days after installationtaken 1 to 10 days after installation

Page 39: Odot- Pda Intro

Restrike testing -fine grained soilsRestrike testing -fine grained soils

log timelog time

capa

city

capa

city

1 da

y1

day

10 d

ays

10 d

ays

100

days

100

days

1000

day

s10

00 d

ays

Technically desirable

Technically desirableEconomically desirable

Economically desirable

Restrike testing generally underRestrike testing generally under--taken 1 to 10 days after installationtaken 1 to 10 days after installation

Page 40: Odot- Pda Intro

CAPWAP METHODCAPWAP METHOD

1 Set up pile model and assume soil model for Rshaft and Rtoe

1 Set up pile model and assume soil model for Rshaft and Rtoe

RshaftRRshaftshaft

RtoeRRtoetoe5 Go to step 25 Go to step 2

4 Adjust 4 Adjust RRshaftshaft andand RRtoetoe

3 Compare 3 Compare FFcc with measured with measured FFmm

2 Apply one measured curve (2 Apply one measured curve (vvmm););Calculate complementary Calculate complementary FFcc

vvmm FFccFFmm

Repeat until match Repeat until match is satisfactoryis satisfactory

Page 41: Odot- Pda Intro

First try (poor)

Final match (good)

CAPWAP

Adjustments

….. is an iterative process

CAPWAP match can be obtained by computer in

fully automatic way!

Page 42: Odot- Pda Intro

PDA testing + CAPWAP leads to calculated load - set curve

PDA testing + CAPWAP PDA testing + CAPWAP leads to calculated load leads to calculated load -- set curveset curve

Page 43: Odot- Pda Intro

Drilled Shaft TestingDrilled Shaft Testing

Page 44: Odot- Pda Intro

PDAPDA

Alternate: Alternate: use hydraulic jawsuse hydraulic jaws

•• Drop weightDrop weight

•• SizeSize

•• drop mechanismdrop mechanism

•• GuidesGuides

•• CushionCushion

•• Pile Pile preparationpreparation

•• Sensor Sensor AttachmentAttachment

Page 45: Odot- Pda Intro

Loading guideLoading guide

20 ton ram20 ton ram(free drop)(free drop)

static tests planned for 70 shafts (1.5 m OD) to 2000 tons static tests planned for 70 shafts (1.5 m OD) to 2000 tons

WestgateWestgate Freeway, Australia, 1982Freeway, Australia, 1982

Page 46: Odot- Pda Intro

MalaysiaMalaysia

30 ton drop weight30 ton drop weight

Page 47: Odot- Pda Intro

40 ton weight 40 ton weight -- PhilippinesPhilippines

Page 48: Odot- Pda Intro

“Big Newton” “Big Newton” in honor of in honor of

Sir Isaac’s F=maSir Isaac’s F=ma

“APPLE” “APPLE” -- AA PPreferred referred PPile ile LLoad oad EEvaluatorvaluator

Page 49: Odot- Pda Intro

OhioOhio

GRL drop hammerGRL drop hammer

(fuel pump removed (fuel pump removed from a diesel hammer)from a diesel hammer)

Plywood cushionPlywood cushion

Page 50: Odot- Pda Intro

OhioOhio

GRL drop hammer >GRL drop hammer >

(fuel pump removed (fuel pump removed from a diesel hammer)from a diesel hammer)

Page 51: Odot- Pda Intro

Drilled Shaft tests Drilled Shaft tests -- Milwaukee StadiumMilwaukee Stadium

•• CSL tests found 15 shafts with soft toesCSL tests found 15 shafts with soft toes

•• Capacity was questionedCapacity was questioned

•• Quote for 2 static tests was $200,000 Quote for 2 static tests was $200,000 $100,000 per test$100,000 per test

•• Quote for 15 PDA tests was $45,000 Quote for 15 PDA tests was $45,000 $3,000 per test$3,000 per test

•• Client tested all 15 shafts with PDA Client tested all 15 shafts with PDA total cost savings: $155,000total cost savings: $155,000

Page 52: Odot- Pda Intro

Vibrator clampsVibrator clampsto free releaseto free releasethe ramthe ram

Ram guideRam guide

20 ton ram20 ton ram

42” drilled shaft42” drilled shaft

Drilled Shaft Testing in MilwaukeeDrilled Shaft Testing in MilwaukeeDrilled Shaft Testing in Milwaukee

Vibrator supportVibrator supportpostsposts

Steel pinSteel pin

2000 ton 2000 ton RuRu

Improvised Drop Hammer made Improvised Drop Hammer made on site: scrap steel bits in tube on site: scrap steel bits in tube (not ideal, but it worked)(not ideal, but it worked)

Page 53: Odot- Pda Intro

RultRult requiredrequired2000 ton 2000 ton 4000 4000 kipskips

CAPWAPCAPWAP

Page 54: Odot- Pda Intro

RultRult requiredrequired2000 ton 2000 ton 4000 4000 kipskips

4 blows in PDA test in Milwaukee4 blows in PDA test in Milwaukee( 20 ton drop weight )( 20 ton drop weight )

Stress OKStress OK RultRult OKOK

Page 55: Odot- Pda Intro

Milwaukee testsMilwaukee tests

PIT done before and PIT done before and after PDA testing after PDA testing for every shaft.for every shaft.

(2 examples shown)(2 examples shown)

PIT results show no PIT results show no damage to shaft due to damage to shaft due to PDA testing and PDA testing and improved toe bearing.improved toe bearing.

Before

Before

After

After

Increased toe resistance

Page 56: Odot- Pda Intro

Conclusions,Conclusions,PDA testing on drilled shafts:PDA testing on drilled shafts:

•• proven worldwide application now proven worldwide application now

•• uses available or easyuses available or easy--toto--make drop hammers make drop hammers and minimal pile preparationand minimal pile preparation

•• confirms capacity, even at large loadsconfirms capacity, even at large loads

•• reduced testing time and large cost savings reduced testing time and large cost savings (cost 10 to 30 times less than static cost) (cost 10 to 30 times less than static cost)

Page 57: Odot- Pda Intro

PDA ConclusionsPDA ConclusionsPDA Conclusions

• PDA with CAPWAP evaluates capacity at low cost for driven piles, drilled shafts,

& augercast piles

• PDA gives extra valuable information (integrity, stresses, hammer energy)

• PDA potentially saves time or pile length in favorable site conditions

• Improves quality control by more pile tests

•• PDA with CAPWAP evaluates capacity at PDA with CAPWAP evaluates capacity at low cost for driven piles, drilled shafts, low cost for driven piles, drilled shafts,

&& augercastaugercast pilespiles

•• PDA gives extra valuable information PDA gives extra valuable information (integrity, stresses, hammer energy)(integrity, stresses, hammer energy)

•• PDA potentially saves time or pile length in PDA potentially saves time or pile length in favorable site conditionsfavorable site conditions

•• Improves quality control by more pile testsImproves quality control by more pile tests

Page 58: Odot- Pda Intro

SPT Testing and Analysis

(Standard Penetration Test)

SPT Testing and AnalysisSPT Testing and Analysis

(Standard Penetration Test)(Standard Penetration Test)

Page 59: Odot- Pda Intro

SPT Purpose:SPT Purpose:

•• NN--value (strength)value (strength)

•• Retrieve soil sampleRetrieve soil sample

Page 60: Odot- Pda Intro

“Standard” Penetration Testing“Standard” Penetration Testing“Non“Non--standard” variablesstandard” variables

• Hammers– Safety– Automatic– Donut

• Operators– Manual– Semi-automatic– Automatic

• Drill Rods– Size– Length

• Hammers– Safety– Automatic– Donut

• Operators– Manual– Semi-automatic– Automatic

• Drill Rods– Size– Length

•• Lift MechanismsLift Mechanisms–– CatheadCathead--roperope–– CatheadCathead diameterdiameter–– Spooling WinchSpooling Winch–– Chain Driven Chain Driven

•• Drill MethodsDrill Methods–– Hollow Stem AugersHollow Stem Augers–– Drilling FluidsDrilling Fluids

•• Split Tube SamplerSplit Tube Sampler–– ShapeShape–– Liners or notLiners or not

Page 61: Odot- Pda Intro

Why measure?Why measure?

•• Due to “nonDue to “non--standard” SPT systems, standard” SPT systems, energy delivered can be highly variableenergy delivered can be highly variable

•• Energy transfer affects N Energy transfer affects N -- value value •• Soil strength estimated from N Soil strength estimated from N -- valuevalue

–– (used in static analysis to estimate capacity)(used in static analysis to estimate capacity)

•• Obtain normalized N Obtain normalized N -- value ( Nvalue ( N60 60 ))•• Improve reliability of soil analysisImprove reliability of soil analysis•• EvaluateEvaluate Liquifaction Liquifaction (ASTM D 6066)(ASTM D 6066)

Page 62: Odot- Pda Intro

SPT Energy TestingSPT Energy Testing

Page 63: Odot- Pda Intro

Energy TransferEnergy Transfer

Hammer Type EFV avg C.O.VOne stdTwo std Samples

Cathead-rope 63 12 55 – 7147 – 79 15

CME automatic 75 9 67 – 8359 – 91 10

Spooling winch 35 8 31 – 39 3Hydraulic auto 69 15 59 – 79 5Donut 43 22 34 – 52 3Other Auto 49 13 42 - 56 6

Data from GRL compiled by Utah StateData from GRL compiled by Utah State

Page 64: Odot- Pda Intro

Comparison of StudiesComparison of Studies

Hammer Study EFV avg C.O.V.

Safety Utah State 63 12

Flordia DOT 66 11

Automatic Utah State 75 9

Flordia DOT 80 8

Page 65: Odot- Pda Intro

Normalized N valueNormalized N value

NN60 60 ==NNmm * E* Emm

{{ WhWh (60%) }(60%) }

Wh Wh (60%) = (60%) = AverageAverage Energy Energy

NNmm = Measured N= Measured N

EEmm = Measured Energy= Measured Energy

Page 66: Odot- Pda Intro

Why measure on SPT?Why measure on SPT?• Energy is variable; affects N - value • Soil strength estimated by N - value

– (used in static analysis to estimate capacity)• Obtain normalized N - value ( N60 )

• Improves reliability of soil analysis• Evaluate Liquifaction (ASTM D 6066)

•• Energy is variable; affects N Energy is variable; affects N -- value value •• Soil strength estimated by N Soil strength estimated by N -- valuevalue

–– (used in static analysis to estimate capacity)(used in static analysis to estimate capacity)•• Obtain normalized N Obtain normalized N -- value ( Nvalue ( N60 60 ))

•• Improves reliability of soil analysisImproves reliability of soil analysis•• EvaluateEvaluate Liquifaction Liquifaction (ASTM D 6066)(ASTM D 6066)

What is the benefit?What is the benefit?

Page 67: Odot- Pda Intro

ConclusionsConclusions• Great potential benefit to industry due to

SPT testing– Better uniformity– Spot problem rigs– Improve predictions using N values– Adjust procedures to get uniform energy

• Great potential benefit to industry due to SPT testing– Better uniformity– Spot problem rigs– Improve predictions using N values– Adjust procedures to get uniform energy

Page 68: Odot- Pda Intro

The EndThe End