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