O-CELL® LOAD TESTING FOR DRILLED SHAFTS AND ACIP PILES

2006 ASCE Florida Section Annual Conference

IMPLEMENTATION OF O-CELLIMPLEMENTATION OF O-CELL®® LOADLOAD TESTING FOR DRILLED SHAFTS TESTING FOR DRILLED SHAFTS

AND AND AUGERED-CAST-IN-PLACE (ACIP) AUGERED-CAST-IN-PLACE (ACIP)

PILESPILES

John HayesJohn Hayes, Senior Project Manager | LoadTest, Inc., Senior Project Manager | LoadTest, Inc.Matthew E. Meyer, P.E.Matthew E. Meyer, P.E., Senior Associate | Langan , Senior Associate | Langan Engineering and Environmental Services, Inc.Engineering and Environmental Services, Inc.


IMPLEMENTATION OF O-CELL LOAD TESTING FOR IMPLEMENTATION OF O-CELL LOAD TESTING FOR DRILLED SHAFTS AND AUGERED-CAST-IN-PLACE DRILLED SHAFTS AND AUGERED-CAST-IN-PLACE

(ACIP) PILES(ACIP) PILES

• Comparison of Conventional Top Load and Comparison of Conventional Top Load and the Osterberg Cell the Osterberg Cell

• O-Cell EvolutionO-Cell Evolution• Limitations and AdvantagesLimitations and Advantages• ApplicationsApplications• Constructability IssuesConstructability Issues• ACIP piles – Necessity leads to InnovationACIP piles – Necessity leads to Innovation• ACIP MilestonesACIP Milestones• InstrumentationInstrumentation


COMPARISON OF O-CELL AND COMPARISON OF O-CELL AND CONVENTIONAL TESTSCONVENTIONAL TESTS


O-Cell Evolution O-Cell Evolution

Evolution of Technology from 1980’s to 2006 Evolution of Technology from 1980’s to 2006

• Pioneering research by Dr. Jorj Osterberg and Pedro Pioneering research by Dr. Jorj Osterberg and Pedro De Silva in the 1980’sDe Silva in the 1980’s

• Osterberg’s impetus - to ascertain the bearing Osterberg’s impetus - to ascertain the bearing capacity within a rock socketcapacity within a rock socket

• Mid-west US and BrazilMid-west US and Brazil• Loadtest Inc. founded in 1991Loadtest Inc. founded in 1991• O-Cells available in sizes ranging from 9” – 34” dia O-Cells available in sizes ranging from 9” – 34” dia

and loads from 200 kips to >64,000 kipsand loads from 200 kips to >64,000 kips• Multi-cell and Multi-level applicationsMulti-cell and Multi-level applications• Bi-directional testing is used globallyBi-directional testing is used globally


O-cell Bi-directional TestingO-cell Bi-directional Testing

Advantages

• No external reaction system

• No anchor piles

• Little or no heavy transport requirements

• Only half the stresses applied to the concrete

• Significant cost savings as loads increase

Limitations

• Pre-selected pile

• Maximum load limited by weaker of end bearing or skin friction

• Test results need interpretation

• Top of the pile is not structurally tested

• Top load movement curve must be calculated


53

33

4

10

11

10

2

13 15

10

36

319

24

1223

17

89

157515

2

12

13

4(NH) 1

(CT) 7

Total USA Tests: 677

(MA) 26

7

2

World record load test set in 2001

(PR) 29

2 Lateral

4

(HI) 34

19(NJ) 31

(MD) 8(DC) 7

(RI) 4

Osterberg Cell Tests Completed in the United States*

*As of September 30, 2005

1

World record load test set in 2003

2


O-cell Tests World-wideO-cell Tests World-wide

1-1011-2021-30>30

0

Upcoming/In progress

Key


3000 ton Conventional3000 ton Conventional2500 ton Conventional2500 ton Conventional

3000 ton O-cell Test3000 ton O-cell Test

No reaction system required

Advantage in many in-situ scenarios including:

off-shore•low concrete cut-offs•confined areas


One Raffles Quay, SingaporeOne Raffles Quay, Singapore(with Gammon Skanska and Meinhardt consultant)(with Gammon Skanska and Meinhardt consultant)

13 tests completed during November and December 2004 – 13 tests completed during November and December 2004 – extremely difficult soil conditions (Boulderly Clay)extremely difficult soil conditions (Boulderly Clay)


Foundation ApplicationsFoundation Applications

• Drilled ShaftsDrilled Shafts• ACIP PilesACIP Piles• Driven PilesDriven Piles• Slurry Walls/BarrettesSlurry Walls/Barrettes


Installation Schematics for Drilled Installation Schematics for Drilled Shafts in South FloridaShafts in South Florida


Connection of O-Cell to Drilled Connection of O-Cell to Drilled ShaftShaft


Drilled Shaft O-Cell and Reinforcing CageDrilled Shaft O-Cell and Reinforcing Cage


THE MULTI-LEVEL O-CELL TEST CAN PROVIDE THE ENGINEER WITH MORE INFORMATION WHEN THE ESTIMATED CAPACITY IN SIDE SHEAR EXCEEDS THAT OF END BEARING

THE TEST ALLOWS THE ENGINEER TO OBTAIN DATA ON THREE OR MORE ISOLATED PILE COMPONENTS (i.e. two or more for shear and one for end bearing)

MULTI-LEVEL O-CELLMULTI-LEVEL O-CELLLOAD TESTINGLOAD TESTING



Multi Level O-cell Shaft Installation


Constructability Issues For O-Cell Constructability Issues For O-Cell Installation in Drilled ShaftsInstallation in Drilled Shafts

• O-Cell diameter to shaft diameterO-Cell diameter to shaft diameter• O-Cell positions and tremie pipe positionO-Cell positions and tremie pipe position• Concrete slump and slump loss vs. timeConcrete slump and slump loss vs. time• Concrete cover on reinforcing cageConcrete cover on reinforcing cage• Spacing between vertical and horizontal Spacing between vertical and horizontal

reinforcing steelreinforcing steel• Horizontal assembly and cage liftingHorizontal assembly and cage lifting


World-Record Drilled Shaft Load World-Record Drilled Shaft Load Test – 62,700 kipsTest – 62,700 kips

… record static load test achieving 62,700 kips (278 MN) on a single 118-inch (3m) diameter foundation pile at the Incheon 2nd Link project in Korea…


O-Cell Development to ACIP Pile O-Cell Development to ACIP Pile Construction TechniqueConstruction Technique

Necessity is the Mother of InventionNecessity is the Mother of Invention-Plato-Plato

Necessity:Necessity:• To economize the testing of ever increasing ACIP pile depth and diameter To economize the testing of ever increasing ACIP pile depth and diameter

• As pile design load increases, testing becomes more costlyAs pile design load increases, testing becomes more costly• O-cell does not require reaction system, no need to drill reaction pilesO-cell does not require reaction system, no need to drill reaction piles• 2,000 kip load test from the surface becomes difficult – e.g. - 2,000 kip load cells are 2,000 kip load test from the surface becomes difficult – e.g. - 2,000 kip load cells are

not readily availablenot readily available• Shorten time for testing – 3x design allows quick test ASTM 4311D standardShorten time for testing – 3x design allows quick test ASTM 4311D standard

Issues Faced:Issues Faced:

• Insertion of reinforcing steel through grouted shaft with O-cell attachedInsertion of reinforcing steel through grouted shaft with O-cell attached• Grout fluidityGrout fluidity• Sufficient cage weightSufficient cage weight• Acceptable O-Cell/ACIP pile diameter ratio – would 50% of available volume be the limit?Acceptable O-Cell/ACIP pile diameter ratio – would 50% of available volume be the limit?• Vertical vs. horizontal assembly (cage bending/racking)Vertical vs. horizontal assembly (cage bending/racking)• Early recognition that entire assembly had to be as straight as possibleEarly recognition that entire assembly had to be as straight as possible• O-Cell to reinforcing cage connection (steel fins vs. traditional plates) O-Cell to reinforcing cage connection (steel fins vs. traditional plates) • Augercast contractors would not change installation technique to suit our method – time Augercast contractors would not change installation technique to suit our method – time

consuming, inefficient (e.g. - more than one crane)consuming, inefficient (e.g. - more than one crane)• InnovateInnovate


Initial ACIP Pile ApplicationsInitial ACIP Pile Applications

Initial applicationsInitial applications• 24-inch-diameter, 100-ft long piles24-inch-diameter, 100-ft long piles

• 13-inch diameter O-cell13-inch diameter O-cell• 2,600 kips (Equivalent Top Load)2,600 kips (Equivalent Top Load)

• 30-inch-diameter, 120-ft long piles30-inch-diameter, 120-ft long piles• 16-inch diameter O-cell16-inch diameter O-cell• 4,240 kips (Equivalent Top Load)4,240 kips (Equivalent Top Load)


Simulation PilesSimulation Piles


Auger cast-in-place (ACIP) pilesAuger cast-in-place (ACIP) piles

Adapting to the Augercast Installation method – or making hockey sticks!


Vertical Vertical AssemblyAssembly

Allowed Allowed cage to flex cage to flex assuring assuring verticality verticality (no hockey (no hockey sticks) sticks)

Welding Welding time time infringing on infringing on installation installation processprocess

Required Required a pilot hole a pilot hole for stingerfor stinger


Innovate - PrefabricationInnovate - Prefabrication

• O-cells and stingers are MIG O-cells and stingers are MIG welded in shop and then shipped welded in shop and then shipped to fieldto field

• ““Fins” replace bearing plates - Fins” replace bearing plates - additional planes to attach rebaradditional planes to attach rebar

• Field welding now limited to upper Field welding now limited to upper cagecage


Additional ModificationsAdditional Modifications

• Plumbers union for TT pipePlumbers union for TT pipe• Taping pipe jointsTaping pipe joints• Sealing of hose joints with Sealing of hose joints with

plumbers puttyplumbers putty

Connection of O-Cell to ACIP Piles


Installation Schematics for ACIP Installation Schematics for ACIP Piles Piles


Evolution of ACIP Pile ApplicationsEvolution of ACIP Pile Applications

ApplicationsApplications• 18-inch-diameter, 80-ft long piles18-inch-diameter, 80-ft long piles

• 9-inch diameter O-cell (800 kip cap.)9-inch diameter O-cell (800 kip cap.)

• 24-inch-diameter, 100-ft long piles24-inch-diameter, 100-ft long piles• 16-inch diameter O-cell (2800 kip cap.)16-inch diameter O-cell (2800 kip cap.)

• 30-inch-diameter, 120-ft long piles30-inch-diameter, 120-ft long piles• 21-inch diameter O-cell (4800 kip cap.)21-inch diameter O-cell (4800 kip cap.)

• 36-inch-diameter, 120-ft long piles36-inch-diameter, 120-ft long piles• Multi-level assembliesMulti-level assemblies• Two 21-inch diameter O-cellTwo 21-inch diameter O-cell• 26-inch? (7200 kip cap.)26-inch? (7200 kip cap.)


Milestones of utilizing O-cell Milestones of utilizing O-cell Technology in Augercast pilesTechnology in Augercast piles

• Incremental records of total load on an ACIP pile – from Incremental records of total load on an ACIP pile – from 2,400 kips to >10,000 kips2,400 kips to >10,000 kips

• Increased O-Cell/shaft diameter ratio from 0.53 to 0.70Increased O-Cell/shaft diameter ratio from 0.53 to 0.70• First multi-level test on an ACIP pile (able to separate First multi-level test on an ACIP pile (able to separate

strata)strata)• Testing some of the deepest ACIP piles worldwide - >145 Testing some of the deepest ACIP piles worldwide - >145

ft. (44 m)ft. (44 m)• Method allows economical testing at 3 times design, Method allows economical testing at 3 times design,

allowing “quick test” standard.allowing “quick test” standard.• Largest known total load applied to an ACIP pile - 10,421 Largest known total load applied to an ACIP pile - 10,421

kipskips


ACIP Pile O-Cell and Reinforcing ACIP Pile O-Cell and Reinforcing CageCage


Multi-level Multi-level O-cell O-cell ACIP ACIP

placementplacement


Schematic of Schematic of InstrumentationInstrumentation• Dial gauges for top of Dial gauges for top of

shaft deflectionshaft deflection• Strain gauges for load Strain gauges for load

distributiondistribution• Top of cell telltales for Top of cell telltales for

compressioncompression• Bottom “fin” tell-tales Bottom “fin” tell-tales

for downward for downward movement and/or O-cell movement and/or O-cell expansionexpansion

• ECT’s at tip of stinger to ECT’s at tip of stinger to measure toe movement measure toe movement


O-cell O-cell Test Set upTest Set up


Implementation of O-Cell Load Testing Implementation of O-Cell Load Testing for Drilled Shafts and Augered Cast-in-for Drilled Shafts and Augered Cast-in-

Place (ACIP) PilesPlace (ACIP) Piles• Drilled shaft load test resultsDrilled shaft load test results• ACIP pile load test resultsACIP pile load test results• Top load test results vs. calculated equivalent top load Top load test results vs. calculated equivalent top load

curvescurves• Load DistributionLoad Distribution• Mobilized side shear for drilled shaftsMobilized side shear for drilled shafts• Mobilized end bearing for drilled shaftsMobilized end bearing for drilled shafts• Strain gauge interpretation (drilled shafts and ACIP Strain gauge interpretation (drilled shafts and ACIP

piles)piles)• Testing DevicesTesting Devices• O-Cell positionsO-Cell positions• Regional ApplicationsRegional Applications


Result of Bi-Directional Load Test:Result of Bi-Directional Load Test:Drilled ShaftsDrilled Shafts


Result of Bi-Directional Load Test:Result of Bi-Directional Load Test:Auger Cast-In-Place (ACIP) PilesAuger Cast-In-Place (ACIP) Piles


Top Load Test: Top Load Test: Predicted vs. Field ResultsPredicted vs. Field Results


Top Load Test Setup:Top Load Test Setup:30-Inch-Diameter ACIP PILE30-Inch-Diameter ACIP PILE


Load Distribution for ACIP Piles:Load Distribution for ACIP Piles:O-Cell Load TestsO-Cell Load Tests


Load Distribution for ACIP PilesLoad Distribution for ACIP PilesTop Load TestsTop Load Tests


Mobilized Side ShearMobilized Side ShearDrilled ShaftsDrilled Shafts


Mobilized End BearingMobilized End BearingDrilled ShaftsDrilled Shafts


Geotechnical Considerations for Geotechnical Considerations for Strain Gauge InterpretationStrain Gauge Interpretation

• Shaft diameterShaft diameter• Shaft roughness/undulationsShaft roughness/undulations• Slurry exposure (filtercake)Slurry exposure (filtercake)• Drilling procedure and casing extraction Drilling procedure and casing extraction

procedureprocedure• Pile diameterPile diameter• Pile undulationsPile undulations• Conditions at test shaft/pile location vs. Conditions at test shaft/pile location vs.

site subsurface conditionssite subsurface conditions


Shaft CaliperShaft Caliper


Shaft DiameterShaft DiameterShaft Caliper Sample Test ResultsShaft Caliper Sample Test Results


Shaft Diameter 3-D RenderingShaft Diameter 3-D Rendering


Shaft Sampling and Inspection Tools:Shaft Sampling and Inspection Tools:Sidewall SamplerSidewall Sampler


Shaft Sampling and Inspection Shaft Sampling and Inspection Tools: Mini-SIDTools: Mini-SID


Caliper Results from ACIP PileCaliper Results from ACIP Pile

• No technique presently available to No technique presently available to determine diameter versus depth of determine diameter versus depth of ACIP pileACIP pile

• Inferences available based on grout Inferences available based on grout factorfactor


O-Cell Positioning ConsiderationsO-Cell Positioning Considerations

• Reaction above and below O-Cell is Reaction above and below O-Cell is necessary to facilitate testingnecessary to facilitate testing

• Proper positioning to evaluate single Proper positioning to evaluate single or multiple bearing layersor multiple bearing layers

• Proper positioning to evaluate end Proper positioning to evaluate end bearing alone or through bearing alone or through instrumentationinstrumentation


Typical Application in South FloridaTypical Application in South Florida


Typical Application in Northern Typical Application in Northern FloridaFlorida


Typical Application in Western Typical Application in Western FloridaFlorida


ConclusionsConclusions

• Full-scale load testing of production sized Full-scale load testing of production sized foundation elements is viablefoundation elements is viable

• Can separate shaft capacity into Can separate shaft capacity into componentscomponents

• Understanding of load distribution with Understanding of load distribution with depth and available side shear with depthdepth and available side shear with depth

• Can obtain end bearing values at various Can obtain end bearing values at various deflectionsdeflections

• Adaptation of existing technology has Adaptation of existing technology has allowed ACIP piles to be O-Cell load testedallowed ACIP piles to be O-Cell load tested

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O-CELL® LOAD TESTING FOR DRILLED SHAFTS AND ACIP PILES

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