Deep FoundationsDeep Foundations

Lesson 9 Lesson 9 -- Topic 3Topic 3Driven Piles Driven Piles -- Load TestingLoad Testing

(Section 9.9.10)(Section 9.9.10)

Learning OutcomesLearning Outcomes

ggAt the end of this session, the At the end of this session, the participant will be able to:participant will be able to:-- Describe types of pile load tests and their Describe types of pile load tests and their

applicationapplication-- Define advantages of pile load testingDefine advantages of pile load testing

Pile Load TestingPile Load Testing

ggPile Load Testing is the Most Positive Pile Load Testing is the Most Positive Method of Determining Pile Capacity.Method of Determining Pile Capacity.

Load Load -- Settlement Graph Settlement Graph

Ultimate Bearing Capacity

Load

Settl

emen

t

Types of Load TestsTypes of Load Tests

RoutineRoutineggStatic Static ggDynamic Dynamic

Other Methods (Discussed in Drilled Other Methods (Discussed in Drilled Shaft Section)Shaft Section)

ggOsterberg Cell Osterberg Cell ggStatnamicStatnamic

Static Load Test Types Static Load Test Types ASTM D1143ASTM D1143ggMaintained LoadMaintained LoadggQuick Load (Texas Quick Test)Quick Load (Texas Quick Test)ggConstant Rate of Penetration (CRP)Constant Rate of Penetration (CRP)

Static Load Test Static Load Test -- Test SetupTest SetupReaction Beam Stiffeners

PlateLoad Cell Spherical Bearing

Ram

Hydraulic Jack Bourdon Gage

Dial GageLVDT

Mirror

ScaleTest Pile

GradeBracket Attached to Pile

Wire

Typical Arrangement for Load Typical Arrangement for Load Testing a Pile or Drilled ShaftTesting a Pile or Drilled Shaft

Reaction BeamReaction Beam

JackJackDial

GageDial

Gage

Test Pile or Drilled ShaftTest Pile or Drilled Shaft

Support Beam

Support Beam

Anchor Pile or Drilled ShaftAnchor Pile or Drilled Shaft

Static Load Test Static Load Test -- MechanismMechanism

Load (Q)

Pile Head

Telltale “A”

Telltale “B”

Telltale “A” Movement

Telltale “B”

Q1+Q2+Q3

Q1+Q2

Q1

Q1+Q2+Q3, etc.

Readout Unit

Jack Pressure Gage

Jack Pump

Hydraulic Jack

Spherical Bearing Plates

Load Cell

Reaction Beam

Reference Beam

Static Load Static Load

Test Load Test Load

Application Application and and

Monitoring Monitoring

ComponentsComponents

Load Test Movement Monitoring ComponentsLoad Test Movement Monitoring Components

LVDTDial Gage

MagneticBase

Reference Beam

SmoothSurface

19-11

Failure CriteriaFailure Criteria

ΔΔ = PL / AE= PL / AE

The commonly used failure criteria are based on the The commonly used failure criteria are based on the elastic pile compression plus an offset.elastic pile compression plus an offset.

The elastic compression, The elastic compression, ΔΔ, is calculated as , is calculated as followsfollows:

Where: P = axial load in kips (Where: P = axial load in kips (kNkN))L = pile length in inches (mm)L = pile length in inches (mm)A = pile cross sectional area in inA = pile cross sectional area in in22 (m(m22))E = elastic modulus of the pile material in E = elastic modulus of the pile material in ksfksf ((kPakPa))

Failure criteria (b < 24 inches)Failure criteria (b < 24 inches)

The recommended offset is based on the pile diameter.

where:sf = Settlement at failure load in inchesb = Pile diameter or width inchesΔ = Elastic deformation of total pile length in inches

In US UnitsIn US Units sf =Δ + (0.15 +b/120)

Failure Criteria (b > 24 inches)Failure Criteria (b > 24 inches)

The recommended offset is based on the pile diameter.

where:sf = Settlement at failure load in inchesb = Pile diameter or width in inchesΔ = Elastic deformation of total pile length in inches

sf = Δ + (b / 30)

QUESTIONQUESTION

ggWould you feel comfortable using a pile Would you feel comfortable using a pile that has been tested to geotechnical that has been tested to geotechnical (plunging) “Failure” in compression as (plunging) “Failure” in compression as a production pile?a production pile?

ggWhy? / Why not?Why? / Why not?

LOAD TRANSFER LOAD TRANSFER EVALUATIONSEVALUATIONSgg Determine relative resistance contributions Determine relative resistance contributions

from shaft and toe.from shaft and toe.

gg Determine load transfer behavior along shaft Determine load transfer behavior along shaft (shaft resistance distribution).(shaft resistance distribution).

gg Confirm, correlate, and calibrate static Confirm, correlate, and calibrate static analyses, WEAP input, CAPWAP soil analyses, WEAP input, CAPWAP soil resistance distributions.resistance distributions.

gg Refine Refine dragloaddragload magnitudes.magnitudes.

VWSG sister bars VWSG sister bars for concrete for concrete embedmentembedment

VWSG with VWSG with welded anchor welded anchor blocks and blocks and protective protective channelchannel

Dynamic Pile TestingDynamic Pile TestingASTM D4945ASTM D4945ggMeasures strain and pile acceleration to Measures strain and pile acceleration to

predict capacitypredict capacityggRequires experienced personnel to Requires experienced personnel to

interpret resultsinterpret resultsggCorrelates well with static test resultsCorrelates well with static test resultsggUsed for timeUsed for time--related capacity changes related capacity changes

Osterberg Load Test ConceptOsterberg Load Test Concept

Qr

Qo

Rs

RtQo

Rt

Rs

Conventional Osterberg

Expanding Osterberg Cell

Reaction System

Osterberg Load Test SetupOsterberg Load Test SetupCell Expansion Telltale

Dial Gage 2

Friction Collar

Dial Gage 1

High Strength PipeShaft Compression TelltalePile Top (Side Shear) Movement Gage

Reference Beam

PrestressedConcrete Pile

Osterberg Cell Cast Into Pile

Pile Shaft Resistance

Hand Operated Hydraulic Pump with Pressure Gage and Pressure Transducer

Osterberg Load Test MechanismOsterberg Load Test Mechanism

Measured Shaft Friction Load Curve

Measured End Bearing Load Curve

Extrapolated Friction Curve

Maximum Load from O-Cell Test

2 3 4 5 6

89

1

7

1 2 34

56

78

910

11

Load

Def

lect

ion

Dow

nD

e fle

c tio

n U

p

Statnamic Load Test ConceptStatnamic Load Test ConceptReaction

Mass

Pressure Chamber

Pile

- FSin

+ FSin

Statnamic Load Test SetupStatnamic Load Test Setup

Pressure Chamber

Load Cell Base Plate Grouted to Foundation

Concrete or Steel Reaction Mass

Loose Granular Fill Propellant

Launching CylinderPiston BaseDisplacement Measuring Means

Pile or Drilled Shaft

Statnamic Load Test MechanismStatnamic Load Test Mechanism

Load (MN)

0

-1

-4

-2

-3

-5

-60 1 2 3 4 5

Dis

plac

emen

t (m

m)

Examples of Cost Savings Examples of Cost Savings From Pile Load TestingFrom Pile Load TestingggWest Seattle Freeway West Seattle Freeway -- Major Project Major Project

Design Phase ProgramDesign Phase ProgramggNorth Carolina DOT North Carolina DOT -- Coordinated Coordinated

Design Phase ProgramsDesign Phase ProgramsggOregon DOT Oregon DOT -- Routine Project Test Routine Project Test

ProgramsPrograms

West Seattle Freeway BridgeWest Seattle Freeway Bridge

West Seattle Freeway Bridge West Seattle Freeway Bridge DesignDesignggFriction Piles for all FoundationsFriction Piles for all Foundations

-- 36” Diameter Open36” Diameter Open--end Pipe Piles for Main end Pipe Piles for Main Channel Piers (24,000 LF driven)Channel Piers (24,000 LF driven)

-- 24” Octagonal Prestressed Concrete Piles 24” Octagonal Prestressed Concrete Piles for Approach Piers (172,000 LF driven)for Approach Piers (172,000 LF driven)

West Seattle Freeway BridgeWest Seattle Freeway Bridge

Item EstimatedSaving

Remarks

Piles $ 9,000,000 -Pile cap size $ 1,000,000 -Test pile dataprovided tobidders

? Difficult toquantify savings

North Carolina Design Phase North Carolina Design Phase Load Test ProgramsLoad Test ProgramsProjects Projects 19941994--19991999

Project Cost Project Cost $ (Bid)$ (Bid)

Test Cost $ Test Cost $ (Bid)(Bid)

Estimated Estimated Savings and (%)Savings and (%)

Neuse Neuse RiverRiver

92,998,00092,998,000 310,000310,000 10,500,000 (11)10,500,000 (11)

New RiverNew River 16,457,00016,457,000 276,000276,000 850,000 (5)850,000 (5)

Chowan Chowan RiverRiver

33,923,00033,923,000 375,000375,000 1,357,000 (4)1,357,000 (4)

Oregon Oregon InletInlet

122,800,000122,800,000 1,155,0001,155,000 1,200,000 (1)1,200,000 (1)

Croatian Croatian SoundSound

88,963,00088,963,000 998,000998,000 1,800,000 (2)1,800,000 (2)

North Carolina Design Phase North Carolina Design Phase Load Test ProgramsLoad Test ProgramsggBenefits to Project DesignBenefits to Project Design

-- Reduction in lengthReduction in length-- Increase in capacityIncrease in capacity-- Reduced number of pilesReduced number of piles-- Driveability, jetting, and setDriveability, jetting, and set--up evaluatedup evaluated-- Improved special provisionsImproved special provisions

North Carolina Design Phase North Carolina Design Phase Load Test ProgramsLoad Test ProgramsggBenefits to Project ConstructionBenefits to Project Construction

-- Improved special provisionsImproved special provisions-- Restructured pay itemsRestructured pay items-- Eliminated unsatisfactory alternatesEliminated unsatisfactory alternates-- Established dynamic test criteriaEstablished dynamic test criteria-- Established pile equipment requirementsEstablished pile equipment requirements-- Reduced potential claimsReduced potential claims

North Carolina Design Phase North Carolina Design Phase Load Test ProgramsLoad Test ProgramsggBenefits of new technology verified….Benefits of new technology verified….

-- Pile driving analyserPile driving analyser-- Osterberg cell axial testOsterberg cell axial test-- Statnamic axial & lateral testStatnamic axial & lateral test-- Integrity test proceduresIntegrity test procedures

….and applied to reduce the costs of ….and applied to reduce the costs of subsequent test programssubsequent test programs

Cost Savings for Oregon DOT from Cost Savings for Oregon DOT from Small Project Pile Load TestsSmall Project Pile Load TestsBridge Bridge

LocationLocationPile Size & Pile Size &

TypeTypeLength Length

ReductionReductionNet Net

SavingsSavingsPiling Piling

SavingSaving

Denny Denny Rd. Rd.

12” Sq. 12” Sq. PrecastPrecast

Concrete 30’Concrete 30’

10’10’ $55,000$55,000 26%26%

Allen Allen BlvdBlvd

12” Sq. 12” Sq. PrecastPrecast

Concrete 30’Concrete 30’

10’10’ $60,000$60,000 20%20%

Airport Airport RdRd

12¾” Closed 12¾” Closed end steel end steel pipe 98’ pipe 98’

30’30’ $135,000$135,000 25%25%

Student Exercise 10Student Exercise 10

ggDetermine the failure Determine the failure laodlaod for the static for the static load test plot shown below. Plot both load test plot shown below. Plot both the elastic line and Davisson failure line the elastic line and Davisson failure line for a 14for a 14--inch square inch square prestressedprestressedconcrete pile 35 ft in length and an concrete pile 35 ft in length and an f’f’cc of of 5,000 5,000 psipsi (Modulus of Elasticity of 4,000 (Modulus of Elasticity of 4,000 ksiksi))

Student Exercise 10Student Exercise 10

Student Exercise 10Student Exercise 10

Use AEPLδ = to find δ @ P = 400 tons (800 kips)

in0.43lbs/in4,000,000in196

in/ft.12ft35lbs800,000δ 22 =×

××=

X = 0.15 in + 14/120 = 0.27 in

Student Exercise 10Student Exercise 10

Learning OutcomesLearning Outcomes

ggAt the end of this session, the At the end of this session, the participant will be able to:participant will be able to:-- Describe types of pile load tests and their Describe types of pile load tests and their

applicationapplication-- Define advantages of pile load testingDefine advantages of pile load testing

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS

Interstate 0 Interstate 0 –– Apple FreewayApple FreewayNote: Scale shown in Station Note: Scale shown in Station FormForm

Baseline Stationing

Baseline Stationing

S.B. Apple Frwy

N.B. Apple Frwy

Proposed Toe of SlopeProposed Toe of Slope

Interstate 0Interstate 0

Existing Ground SurfaceExisting Ground Surface

12

Proposed Final GradeProposed Final GradeProposed AbutmentProposed Abutment

9090 9191 9292 9393

Apple Apple Freeway Freeway ExerciseExercise

ggAppendix AAppendix A-- Section A.8Section A.8

Subsurface Explorations Terrain Reconnaissance Site Inspection Subsurface Borings

Basic Soil Properties Visual Description

Classification Tests Soil Profile

Laboratory Testing Po Diagram

Test Request Consolidation Results Strength Results

Slope Stability

Design Soil Profile Circular Arc Analysis Sliding Block Analysis Lateral Squeeze

Approach Roadway Settlement

Design Soil Profile Settlement Time – Rate Surcharge Vertical Drains

Spread Footing Design Design Soil Profile

Pier Bearing Capacity Pier Settlement Abutment Settlement Surcharge Vertical Drains

Driven Pile Design

Construction Monitoring

Wave Equation Hammer Approval Embankment Instrumentation

Design Soil Profile Static Analysis – Pier Pipe Pile H – Pile Static Analysis – abutment Pipe Pile H – Pile Driving Resistance Abutment Lateral Movement

Design Check of Design Check of DriveabilityDriveability of of 12x84 H12x84 H--pilepile

Wave Equation Results Over 75Wave Equation Results Over 75--ft Depth for ICE 70S Hammerft Depth for ICE 70S Hammer

Diesel Hammer Stroke Diesel Hammer Stroke vsvs Blow Blow Count at 75Count at 75--ftft

Construction AspectsConstruction Aspects

ggPile Pile DriveabilityDriveability-- DriveabilityDriveability of 12x84 Hof 12x84 H--pile section verified pile section verified

for most difficult driving conditionfor most difficult driving conditionggDriveabilityDriveability with Depthwith Depth

-- DriveabilityDriveability of 12x84 Hof 12x84 H--pile section pile section computed for whole 75computed for whole 75--ft depthft depth

-- Pile installation time expected to vary Pile installation time expected to vary between 16 and 20 minutes (no prebetween 16 and 20 minutes (no pre--augeringaugering))

Any Questions?Any Questions?

THE ROAD TOUNDERSTANDING

SOILSAND

FOUNDATIONS