odot- pit and csl overview
TRANSCRIPT
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GRLGRLDynamic Testing Methods for
Evaluation of Integrity andCapacity for Drilled Shafts
Dynamic Testing Methods for
Evaluation of Integrity andCapacity for Drilled Shafts
CSL
CSL
PDAPDAPDA PITPITPIT
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GRLGRLDeep Foundation Solutions:
Driven Piles
Steel, Concrete, Timber
Drilled Shafts Wet or Dry, Cased or Uncased
Augercast Piles
Each pile type has differentinspection needs
Deep Foundation Solutions:Deep Foundation Solutions:
Driven PilesDriven Piles
Steel, Concrete, Timber Steel, Concrete, Timber
Drilled ShaftsDrilled Shafts Wet or Dry, Cased orWet or Dry, Cased or UncasedUncased
AugercastAugercast PilesPiles
Each pile type has differentEach pile type has differentinspection needsinspection needs
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Planned inspection
Included in project specifications
Planned costs - normal pay item
Unplanned inspection
in response to something gone wrong
Unplanned costs - who pays?
Delays project, extra claims
Planned inspectionPlanned inspection
Included in project specificationsIncluded in project specifications
Planned costsPlanned costs -- normal pay itemnormal pay item
Unplanned inspectionUnplanned inspection
in response to something gone wrongin response to something gone wrong
Unplanned costsUnplanned costs -- who pays?who pays?
Delays project, extra claimsDelays project, extra claims
( Preferred )( Preferred )( Preferred )
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Low Strain Integrity MethodsLow Strain Integrity MethodsLow Strain Integrity Methods
PILE INTEGRITY TESTING (PIT) Measure Pile Top Motion, Reflections from Defects For concrete piles, concrete filled pipes, drilled
shafts, augercast piles, and sometimes timber piles.
CROSS-HOLE SONIC LOGGING (CSL) Determines Concrete Quality Between Tubes in Shaft For drilled shafts and larger augercast piles
PILE INTEGRITY TESTING (PIT)PILE INTEGRITY TESTING (PIT) Measure Pile Top Motion, Reflections from DefectsMeasure Pile Top Motion, Reflections from Defects For concrete piles, concrete filled pipes, drilledFor concrete piles, concrete filled pipes, drilled
shafts,shafts, augercastaugercast piles, and sometimes timber piles.piles, and sometimes timber piles.
CROSSCROSS --HOLE SONIC LOGGING (CSL)HOLE SONIC LOGGING (CSL) Determines Concrete Quality Between Tubes in ShaftDetermines Concrete Quality Between Tubes in Shaft For drilled shafts and largerFor drilled shafts and larger augercastaugercast pilespiles
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GRLGRLPile Integrity Testing...
looks for major defects
Pile Integrity Testing...
looks for
major defectsSmall hammerimpact device Accelerometer
measures response
(defect)
ASTM D5882ASTM D5882
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Local Defect: small medium large
Local Bulge: small medium large
PIT - Basic InterpretationsPITPIT -- Basic InterpretationsBasic Interpretations
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GRLGRLNormal test
(pile top free)
800 mm drilled shafts800 mm drilled shafts
L = 25 m (L/D = 31)L = 25 m (L/D = 31)
Good PileGood Pile
Bad PileBad Pile
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14 inch14 inch augercastaugercast pile with 15 foot rebars.pile with 15 foot rebars.
Failed static load testFailed static load test often prompts testing.often prompts testing.
Defect in this test pile shaft caused failed testDefect in this test pile shaft caused failed test(rather than soil failure)(rather than soil failure)
GRL#994034
Test Pile
DefectDefect
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GRLGRLPIT detected bored pile defect at 4.1 m depth;PIT detected bored pile defect at 4.1 m depth;confirmed by coreconfirmed by core
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Good pile with local bulgeat about 25 ft and clear toe
Bulge- / + cycle
Bad pile with major defect atabout 3.5 ft and no clear toe
Neck+ / - cycleBad pile excavatedto reveal neck
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GRLGRLClassifications(4 categories proposed by GRL)
Classifications(4 categories proposed by GRL)
AA -- Good PileGood PileClear toe response, no obvious defect; sound shaftClear toe response, no obvious defect; sound shaft
BB -- Bad PileBad PileClear identification of serious defect;Clear identification of serious defect; no toe signalno toe signal
needs contingency tests or corrective measuresneeds contingency tests or corrective measures CC -- Possible DefectPossible Defect
rere --test, other tests, reduce capacity or replacetest, other tests, reduce capacity or replace
DD -- Inconclusive dataInconclusive data(poor pile top quality,(poor pile top quality,
or no reflections due to strong soil)or no reflections due to strong soil) fix pile top & refix pile top & re --test; might givetest; might give infoinfo for upper pile shaftfor upper pile shaft
which is reason to accept pile.which is reason to accept pile.
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Compare with other observationsCompare with other observations
ReRe --test with PIT (trim pile top to solid concrete)test with PIT (trim pile top to solid concrete) Excavate if near topExcavate if near top
Request pile coreRequest pile core Request a PDA test or a static testRequest a PDA test or a static test Replace pile (or repair)Replace pile (or repair) Other?Other?
Have a planHave a plan what to do if find a defectwhat to do if find a defect
What to do if find a problem ?What to do if find a problem ?
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Some studies suggest a 30 L/DSome studies suggest a 30 L/D limit.limit.Actually this is only a rule of thumb andActually this is only a rule of thumb anduseable length depends on:useable length depends on:
soil strength,soil strength, pile uniformity,pile uniformity,
actual diameter and length,actual diameter and length, and equipment noise and resolution.and equipment noise and resolution.
We often see much farther We often see much farther
PIT LimitationsPIT Limitations
Highly nonHighly non --uniform piles difficult to interpretuniform piles difficult to interpret Cracks or mechanical joints block wavesCracks or mechanical joints block waves
Small defects (or of short length) hard to findSmall defects (or of short length) hard to find Gradual changes hard to findGradual changes hard to find
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GRLGRLPIT ConclusionsPIT ConclusionsPIT Conclusions
PIT finds major defects,
low cost so can test every pile Inclusion of inspection requirements in
job specifications is suggested PIT can sometimes test piles in structure
Guideline of use till 30 L/D is not a limit.
Cracks or gaps limit transmission of wave
No information about capacity
PIT findsPIT finds major defectsmajor defects ,,
low cost so can test every pilelow cost so can test every pile Inclusion of inspection requirements inInclusion of inspection requirements in
job specifications is suggested job specifications is suggested PIT can sometimes test piles in structurePIT can sometimes test piles in structure
Guideline of use till 30 L/D is not a limit.Guideline of use till 30 L/D is not a limit.
Cracks or gaps limit transmission of waveCracks or gaps limit transmission of wave
No information about capacityNo information about capacity
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Stress Waves, emittedStress Waves, emittedin one tube are receivedin one tube are received
in another one if concretein another one if concrete
quality is satisfactoryquality is satisfactory
ReceiveReceiveTransmit Transmit
Cross Hole Sonic Logging
ASTM D6760
Cross Hole Sonic LoggingCross Hole Sonic Logging
ASTM D6760ASTM D6760
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Cross Hole Sonic Logging
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SignalSignal
(wave speed) = ( tube distance ) / (arrival time )(wave speed) = ( tube distance ) / (arrival time )
Arrival
Energy
Cross Hole Sonic Logging
Arrival
Arrival
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DefectDefect
DefectDefect
DefectDefect
How do we spot defects?How do we spot defects?Low energyLow energyLate arrivalsLate arrivals
Cross Hole Sonic Logging
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GRLGRL48 shaft with soft toe condition48 shaft with soft toe condition
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GRLGRLShaft with tremie defect
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insensitive to surrounding soil or pile lengthinsensitive to surrounding soil or pile length
finds multiple defects, depth and quadrantfinds multiple defects, depth and quadrant
finds soft bottoms if tubes go to bottomfinds soft bottoms if tubes go to bottom inspires careful construction by contractor inspires careful construction by contractor
CSL Testing AdvantagesCSL Testing Advantages
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must plan and install access tubesmust plan and install access tubes tubes preferably less than 2 meters aparttubes preferably less than 2 meters apart
evaluates concrete only between tube pairsevaluates concrete only between tube pairs
defects undetected when outside cagedefects undetected when outside cage
CSL Testing LimitationsCSL Testing Limitations
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GRLGRLCSL ConclusionsCSL ConclusionsCSL Conclusions Can find multiple defects and their quadrant;
not sensitive to pile length or soil
CSL finds defects between (steel) access tubes;consider defect remedy in advance
CSL access tubes in every shaft inspireshigh quality installation for every shaft
(even if do not test every shaft)
Allows low cost testing access if problems occurduring installation
Waterfall, FAT and energy complimentinterpretation of results
Can find multiple defects and their quadrant;Can find multiple defects and their quadrant;not sensitive to pile length or soil not sensitive to pile length or soil
CSL finds defects between (steel) access tubes;CSL finds defects between (steel) access tubes;consider defect remedy in advanceconsider defect remedy in advance
CSL access tubesCSL access tubes in every shaft in every shaft inspiresinspireshigh quality installation for every shafthigh quality installation for every shaft
(even if do not test every shaft)(even if do not test every shaft)
Allows low cost testing access if problems occur Allows low cost testing access if problems occurduring installationduring installation
Waterfall, FAT and energy complimentWaterfall, FAT and energy complimentinterpretation of resultsinterpretation of results
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The ndhe nd