Frank Rausche2011, Pile Dynamics, Inc.
GRLWEAP: Fundamentals, Models, ResultsGRLWEAP: Fundamentals, Models, Results
Background – Part 1Background – Part 1
• History and Objectives• History and Objectives
• Wave Equation Pile Model• Wave Equation Pile Model• Hammer Models• Hammer Models• Wave Equation Soil Model• Wave Equation Soil Model
• Program Flow –• Bearing Graph
• Inspector’s Chart
• Program Flow –• Bearing Graph
• Inspector’s Chart
• Wave Equation Numerics• Wave Equation Numerics
• Driven Pile Design, Energy Concepts• Driven Pile Design, Energy Concepts
1800s Closed Form Solutions1850s First Energy Formula1950: Smith’s Wave Equation1960s Dynamic Testing and CAPWAP1976: WEAP, TTI1980s: GRLWEAP1986: Hammer Performance Study1996, 2006: FHWA Manual updates
Dynamic Pile Analysis Developments
WAVE EQUATION OBJECTIVESWAVE EQUATION OBJECTIVES
• Smith’s Basic Premise: – Replace Energy Formula– Use improved pile model (elastic pile) and soil model
(elasto-plastic static resistance with damping)– Allow for realistic stress calculations
• Additional GRLWEAP developments expand the basic capabilities Inspectors’ Graph analysis option Driveability analysis option Diesel hammer analysis Residual stress analysis Static geotechnical analyses Special offshore analysis options
GRLWEAP Analysis OptionsGRLWEAP Analysis Options
• Bearing Graph for capacity from observed blow count– Hammer performance fixed– One depth– Assumed capacity values (10)
• Inspectors’ Chart for required blow count– Hammer performance variable– One depth– One capacity
• Driveability Analysis for anticipated blow counts– Hammer performance fixed– Assumed depth values (100)– Several capacity values for each depth (5)
GRLWEAP ObjectivesGRLWEAP Objectives
• WHEN SHOULD WE DO THE ANALYSIS?– Before pile driving begins
– After initial pile tests have been done (refined)
• FOR WHAT PURPOSE?– Formulate driving criterion:
• Safe stresses
• Required blow count for sufficient capacity
– Adequate equipment (e.g., hammer) selection
– Pile stress determination
– Blow count calculation for required capacity
– Capacity from observed blow count
Basic design approach for driven pilesBasic design approach for driven piles
1. Obtain Design Load (Qd) from structural design
2. Decide on Safety Concept (FS)
3. Decide on Pile Type based on suitability and availability
4. Perform Static Pile Analysis, determine Ultimate Capacity (Ru) for assumed Pile Length.
5. Find Pile Length so that Ru > FS Qd
Basic design approach continuedBasic design approach continued
6. Compute Blow Count for Ru - check Driveability by GRLWEAP
7. Either perform an initial Test Program, testing piles dynamically, sometimes statically
8. Establish Installation Criterion (min. penetration, required blow count)
9. Install Production Piles to criterion
10.For all production piles, final pile length is determined at installation time
Reference:
Hannigan, P.J., G.G. Goble, G.E. Likins, and F. Rausche. Design and Construction of Driven Pile Foundations - Volumes 1 and 2. Publication Numbers FHWA-NHI-05-042 and 043. Washington, D.C.: U.S. Department of Transportation Federal Highway Administration, 2006.
Factor of SafetyFactor of Safety
Ru ≤ (FS) Qd
• Ru Ultimate Capacity
(Nominal or Characteristic Resistance)
• FS Global Factor of Safety (1.5 < F.S. < 10)
(for LRFD: FS =Combined Load/Resistance Factor)
• Qd Design Load
(Safe Load, Working Load, Sum of Unfactored
Loads)
GRLWEAP works exclusively with Ru
Static Analysis MethodsStatic Analysis Methods
Ru = Rs + Rt
Ru = fsAs + qt At
fs, As …Unit/Shaft Resistance, Area
qt, At … Unit/End Bearing, Area
Ru = Rs + Rt
Ru = fsAs + qt At
fs, As …Unit/Shaft Resistance, Area
qt, At … Unit/End Bearing, Area
Rs
Rt
Q
The α-Method For example: Total Stress method for cohesive soils
The α-Method For example: Total Stress method for cohesive soils
• Rs = fs As with fs = α cUα is an empirical adhesion factor
cU is the undrained shear strength
• Rt = 9 cU
After Tomlinson, 1979
• Rs = fs As with fs = α cUα is an empirical adhesion factor
cU is the undrained shear strength
• Rt = 9 cU
After Tomlinson, 1979
The β-Method primarily for cohesionless soils
The β-Method primarily for cohesionless soils
• Rs = fs As with fs = β po β = ko tan(δ)po is the effective overburden pressure
ko is some earth pressure coefficient
• Rt = Nt po AtNt is a bearing
capacity factor
after Fellenius, 1991
... with certain limits
• Rs = fs As with fs = β po β = ko tan(δ)po is the effective overburden pressure
ko is some earth pressure coefficient
• Rt = Nt po AtNt is a bearing
capacity factor
after Fellenius, 1991
... with certain limits
Static Analysis MethodsStatic Analysis Methods
GRLWEAP’s Static Analysis Methods
GRLWEAP’s Static Analysis Methods
Rs
Rt
Q
Icon Input Basic AnalysisST Soil Type Effective Stress, Total StressSA SPT N-value Effective StressCPT R at cone tip and sleeve SchmertmannAPI φ, Su Effective Stress, Total Stress
• GRLWEAP’s static analysis methods may be used for dynamic analysis preparation (resistance distribution, estimate of capacity for driveability).
• For design, be sure to use a method based on local experience.
Use of Static Analysis MethodsUse of Static Analysis Methods
• Should always be done for finding reasonable pile type and length
• For driven piles static analysis is only a starting point, since pile length is determined in the field (exceptions are piles driven to depth, for example, because of high soil setup)
• For LRFD when finding pile length by static analysis method use resistance factor for selected capacity verification method
Energy ConsiderationsIf we take PDA measurements….
Energy ConsiderationsIf we take PDA measurements….
…we can calculate the Transferred Energy
WR
h
ER = WR hManufacturer’s Rating
WR
Max ET = ∫F(t) v(t) dt(ENTHRU)
ηT = ENTHRU/ ER
(transfer ratio or efficiency)Measure Force, F(t)Velocity, v(t)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
PE
RC
EN
TIL
E
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
DIESEL HAMMERS ON STEEL PILESN = 732; MEDIAN = 36.8%
ENERGY TRANSFER RATIO [EMX / E-RATED]
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
FR
EQ
UE
NC
Y
0-5% 10-15% 20-25% 30-35% 40-45% 50-55% 60-65% 70-75% 80-85% 90-95%
ENERGY TRANSFER RATIO [EMX / E-RATED]
MEAN = 36.8%STANDARD DEVIATION = 9.5%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
PE
RC
EN
TIL
E
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
DIESEL HAMMERS ON CONC./TIMBER PILESN = 394; MEDIAN = 24.9%
ENERGY TRANSFER RATIO [EMX / E-RATED]
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
FR
EQ
UE
NC
Y
0-5% 10-15% 20-25% 30-35% 40-45% 50-55% 60-65% 70-75% 80-85% 90-95%
ENERGY TRANSFER RATIO [EMX / E-RATED]
MEAN = 26.1%STANDARD DEVIATION = 7.9%
For all impact hammers GRLWEAP needs impact velocity
WP
WR
hEP = WR h (potential, ideal)
EP = WR h η (η = Hammer efficiency )WR
vi
EK = ½ mR vi2 (kinetic energy)
mR = WR / gEP = EK
vi = 2g hη
Energy (Dynamic) FormulasEnergy (Dynamic) Formulas
Energy Dissipated in Soil =
Energy Provided by Hammer
Ru (s + sl) = ηWr h
sl … “lost” set (empirical or measured),
η … efficiency of hammer/driving system
Energy Dissipated in Soil =
Energy Provided by Hammer
Ru (s + sl) = ηWr h
sl … “lost” set (empirical or measured),
η … efficiency of hammer/driving system
Bearing Graphs from 2 Energy FormulasHammer D 19-42; Er = 59 kJ
Bearing Graphs from 2 Energy FormulasHammer D 19-42; Er = 59 kJ
0
500
1000
1500
2000
2500
3000
3500
4000
0 25 50 75 100 125 150 175 200
Blows/0.25 m
Ca
pa
cit
y in
kN
Gates - w/ calculated Stroke ENR - Ru = Rd x 2
Ru = ηEr /(s + sl)η = 1/3; sl = 2.5mm
Ru = 1.6 Ep ½ log(10Blows/25mm) – 120 kN
4000[900]
Ru - kN[kips]
2000[450]
0
0 5 10 15 20Blows/25mm
THE WAVE EQUATION MODELTHE WAVE EQUATION MODEL
• The Wave Equation Analysis calculates the displacement of any point of a slender elastic rod at any time.
• The calculation is based on rod
– Length
– Cross Sectional Area
– Elastic Modulus
– Mass density
GRLWEAP FundamentalsGRLWEAP Fundamentals
• For a pile driving analysis, the “rod” is Hammer+Driving System+Pile
• The rod is assumed to be elastic(?) and slender(?)
• The soil is represented by resistance forces acting at the pile soil interface
Ham
mer
D.S.
Pil
eGRLWEAP Pile ModelGRLWEAP Pile Model
To solve the wave equation numerically:• The pile is divided into N segments
– of approximate length ∆L typically: ∆L = 1 m (3.3 ft)
– with mass m = ρ A ∆L
– and stiffness k = E A / ∆L
– there are N = L / ∆L pile segments
• The analysis time is divided into intervalstypically: ∆t = 0.1 ms
∆L
GRLWEAP Time Increment, ∆tGRLWEAP Time Increment, ∆t∆t is a fraction (e.g. ½ ) of the critical time, which is ∆L/c∆t is a fraction (e.g. ½ ) of the critical time, which is ∆L/c
∆tcr
∆ L
L/c
∆t
Time
Length
GRLWEAP Hammer ModelsGRLWEAP Hammer Models
Ram: A, L for stiffness, mass
Cylinder and upper frame = assembly top mass
Drop height
External Combustion Hammer ModelingExternal Combustion Hammer Modeling
Ram guides for assembly stiffness
Hammer base = assembly bottom mass
External Combustion Hammer ModelExternal Combustion Hammer Model
• Ram modeled like rod
• Stroke is an input (Energy/Ram Weight)
• Impact Velocity Calculated from Stroke with Hammer Efficiency Reduction: vi = (2 g h η) ½
• Assembly also modeled because it may impact during pile rebound
• Note approximation in data file:
Assembly mass = Total hammer mass – Ram mass
External Combustion HammersRam Model
External Combustion HammersRam Model
Ram segments ~1m long
Ram segments ~1m long
Combined Ram-H.Cushion
Helmet mass
Combined Ram-H.Cushion
Helmet mass
External Combustion HammersCombined Ram Assembly Model
External Combustion HammersCombined Ram Assembly Model
Combined Ram-H.Cushion
Helmet mass
Combined Ram-H.Cushion
Helmet mass
Ram segments
Assembly segments
Ram segments
Assembly segments
External Combustion HammerProcedure
External Combustion HammerProcedure
• Static equilibrium analysis
• Dynamic analysis starts when ram is within 1 ms of impact.
• All ram segments then have velocity
VRAM = (2 g h η)1/2 – 0.001 gg is the gravitational acceleration
h is the equivalent hammer stroke and η is the hammer efficiency
h = Hammer potential energy/ Ram weight
External Combustion HammerProcedure
External Combustion HammerProcedure
• Dynamic analysis ends when
– Pile toe has rebounded to 80% of max dtoe
– Pile has penetrated more than 4 inches
– Pile toe has rebounded to 98% of max dtoe and energy in pile is essentially dissipated
DIESEL HAMMERSDIESEL HAMMERSClosed Ended Open Ended
Diesel hammer componentsDiesel hammer components
Piston = RamPiston = Ram
Port (closed by piston)Port (closed by piston)
Combustion chamberCombustion chamber
Impact blockImpact block
Hammer Cushion; HelmetHammer Cushion; Helmet
CylinderCylinder
Compressive strokeCompressive stroke
DIESEL Hammer MODELDIESEL Hammer MODEL
• Ram, Impact Block modeled like rods• Compression, Expansion Pressures from Gas
Law• Combustion Pressure from rated energy –
measurements; different for Atomized and Liquid Fuel injection
• Ram velocity reduced by efficiency just before impact
• Ram, Impact Block modeled like rods• Compression, Expansion Pressures from Gas
Law• Combustion Pressure from rated energy –
measurements; different for Atomized and Liquid Fuel injection
• Ram velocity reduced by efficiency just before impact
Diesel Hammer Ram ModelDiesel Hammer Ram Model
Hammer Cushion
Helmet mass
Hammer Cushion
Helmet mass
Ram segments ~1m longRam segments ~1m long
Impact Block massImpact Block mass
Ram bottom/impact blockRam bottom/impact block
Diesel Hammer Combustion Pressure ModelDiesel Hammer Combustion Pressure Model
Precompression-Combustion-Expansion-Pressure
Precompression-Combustion-Expansion-Pressure
PortsPorts
• Compressive Stroke, hC
• Cylinder Area, ACH
• Final Chamber Volume, VCH
• Max. Pressure, pMAX
• Compressive Stroke, hC
• Cylinder Area, ACH
• Final Chamber Volume, VCH
• Max. Pressure, pMAX
hChC
DIESEL PRESSURE MODELLiquid Injection Hammers
DIESEL PRESSURE MODELLiquid Injection Hammers
TimeTime
Pressure
Por
t
Ope
ns
Por
t
Ope
ns
Compression:
p=patm(Vin/V)1.35
Compression:
p=patm(Vin/V)1.35
pMAX
Expansion:
p=pMAX(VCH/V)1.25
Expansion:
p=pMAX(VCH/V)1.25tD
Combustion Duration, tDCombustion Duration, tD
Combustion Delay, ∆tCombustion Delay, ∆t
∆t
Downward = upward stroke
Program Flow – Diesel HammersFixed pressure, variable stroke
Program Flow – Diesel HammersFixed pressure, variable stroke
Downward = rated stroke
Calculate pile andram motion
Find upward stroke
Output
Strokes match?
Setup hammer,pile, soil model
Next Ru?
N
N
GRLWEAP hammer efficiencies (Ek/EP)GRLWEAP hammer efficiencies (Ek/EP)
•The hammer efficiency reduces the impact velocity of the ram; it is based on experience•Hammer efficiencies cover all losses which cannot be calculated•Diesel hammer energy loss due to pre-compression or cushioning can be calculated and, therefore, is not covered by hammer efficiency
GRLWEAP diesel hammer efficienciesGRLWEAP diesel hammer efficiencies
Open end diesel hammers: 0.80uncertainty of fall height, friction, alignment
Closed end diesel hammers: 0.80uncertainty of fall height, friction, power assist, alignment
Modern Hydraulic Hammer Efficiencies
Modern Hydraulic Hammer Efficiencies
Hammers with internal monitor: 0.95uncertainty of hammer alignment
Hydraulic drop hammers: 0.80uncertainty of fall height, alignment, friction
Power assisted hydraulic hammers: 0.80uncertainty of fall height, alignment, friction, power assist
Air/Steam/Traditional Hydraulic Hammer Efficiency Recommendations
Air/Steam/Traditional Hydraulic Hammer Efficiency Recommendations
Single acting Air/Steam hammers: 0.67fall height, preadmission, friction, alignment
Double acting Air/Steam/Hydraulic: 0.50preadmission, reduced pressure, friction, alignment
Drop HammerEfficiency Recommendations
Drop HammerEfficiency Recommendations
• Drop hammers brake released: 0.50covers uncertainty of fall height and winch losses
• Drop hammers free released: 0.67covers uncertainty of fall height
VIBRATORY HAMMER MODEL
VIBRATORY HAMMER MODEL
VIBRATORY HAMMER MODELVIBRATORY HAMMER MODEL
Vibratory Force:FV = me [ω2resin ω t - a2(t)]
FLFL
FVFV
m1m1
m2m2
• Line Force
• Bias Mass and
• Oscillator mass, m2
• Eccentric masses, me, radii, re
• Clamp
GRLWEAP Hammer data fileGRLWEAP Hammer data file
Driving System ModelingDriving System Modeling
Driving Systems Consists of1. Helmet including inserts to align hammer and pile
2. Hammer Cushion to protect hammer
3. Pile Cushion to protect concrete piles
Driving system model (Concrete
piles)
Driving system model (Concrete
piles)
Pile Cushion + Pile Top: Spring + Dashpot
Pile Cushion + Pile Top: Spring + Dashpot
Helmet + InsertsHelmet + Inserts
Hammer Cushion: Spring plus Dashpot
Hammer Cushion: Spring plus Dashpot
Non-linear springsfor cushions and slacks
Non-linear springsfor cushions and slacks
Parameters1. Stiffness, k = EA/t
2. Coefficient of Restitution, COR
3. Round-out deformation, δr , or compressive slack
4. Tension slack, δs
δrδr
k /COR2k /COR2k
δsδsCompressive Deformation
Compressive Deformation
Compressive ForceCompressive Force
Non-linear springsSprings at material interfaces
Non-linear springsSprings at material interfaces
Hammer interface springs
Cushions
Helmet/Pile
Splices with slacks
Hammer interface springs
Cushions
Helmet/Pile
Splices with slacks
∆L= L/N 1m (default)
Soil ModelSpring (static resistance)
Dashpot (dynamic resistance)
Mass density, Modulus, EX-Area, A
Mass, mi
Stiffness, ki
The Pile and Soil ModelThe Pile and Soil Model
Soil ResistanceSoil Resistance
• Soil resistance slows pile movement and causes pile rebound
• A very slowly moving pile only encounters static resistance
• A rapidly moving pile also encounters dynamic resistance
• The static resistance to driving differs from the soil resistance under static loads
Soil Model ParametersSoil Model Parameters
Segment
i
ki,Rui
Ji
RIGID SOIL
Segment
i-1
Segment
i+1
ki+1,Rui+1
Ji+1
ki-1,Rui-1
Ji-1
Pile
-So
il In
terf
ace
Smith’s Soil ModelSmith’s Soil Model
Total Soil ResistanceRtotal = Rsi +Rdi
Total Soil ResistanceRtotal = Rsi +Rdi
Segment
i
ui
vi
Fixed
Rigid plastic slider with Resistance Rui
Elastic spring with max. compression q (quake)
Fixed referenceFixed reference
ui
Rui
Rsi
ksi = Rui /qi
1
quake, qi
Static Shaft Resistance ModelParameters Rui, qi
Static Shaft Resistance ModelParameters Rui, qi
Shaft Resistance and QuakeShaft Resistance and Quake
qi
Rui
qi
Rsi
ui
-Rui
Recommended Shaft Quake:
2.5 mm; 0.1 inches
Recommended Toe Quakes, qtRecommended Toe Quakes, qt
0.1” or 2.5 mm
0.04” or 1 mm on hard rock
qt
RqtRut
u
D/120: very dense/hard soils
D/60: softer/loose soils
Displacement pilesNon-displacement piles
D
Smith’s Soil Damping Model (Shaft or Toe)Smith’s Soil Damping Model (Shaft or Toe)
PileSegment
Smith damping factor,Js [s/m or s/ft]
Rd = RsJs v
Fixed reference (soil around pile)
velocity v
Rd = RuJsv v
Smith-viscous damping factor Jsv [s/m or s/ft]
For RSA and Vibratory Ananlysis
dashpot
Recommended Smith damping factorsRecommended Smith damping factors
Shaft
Clay: 0.65 s/m or 0.20 s/ft
Sand: 0.16 s/m or 0.05 s/ft
Silts: use an intermediate value
Layered soils: use a weighted averagefor bearing graph
Toe
All soils: 0.50 s/m or 0.15 s/ft
GRLWEAP Help forDynamic Soil Resistance Parameters
GRLWEAP Help forDynamic Soil Resistance Parameters
How to Distribute the Static Soil Resistance Along Pile and at ToeHow to Distribute the Static Soil
Resistance Along Pile and at Toe
1. SimplestI. Percentage Shaft resistance
(from static soils analysis)II. Triangular or Rectangular or
Trapezoidal
Only Reasonable for a simple Bearing Graph where little is known
about soil.
End Bearing = Total Capacity x (100% - Percent Shaft
Resistance)
Pen
etra
tio
n
How to Distribute the Static Soil Resistance Along Pile and at toeHow to Distribute the Static Soil Resistance Along Pile and at toe
2. Still Simple:ST Analysis based on some knowledge of Soil Types
Reasonable for a simple Bearing Graph; for Driveability possible, but more accurate analysis should be
done.
End Bearing = From Soil Type, Pile Bottom Area
Pen
etra
tio
n
How to Distribute the Static Soil Resistance Along Pile and at toeHow to Distribute the Static Soil Resistance Along Pile and at toe
3. More Involved:I. SA
Input: SPT Blow Count, Friction Angle or Undrained Shear Strength
II. APIInput: Friction Angle or Undrained Shear Strength
III. CPTInput: Cone Record including tip resistance and Sleeve Friction vsdepth.
Pen
etra
tio
n
All are good for a Bearing GraphMay be OK for Driveability Analysis
Local experience may provide better values
Numerical TreatmentNumerical Treatment
• Predict displacements:
uni = uoi + voi ∆t
• Predict displacements:
uni = uoi + voi ∆t
Fi, ci
uni-1
mi
mi+1
mi-1
uni
uni+1
Ri-1
Ri
Ri+1
• Calculate spring compression:
ci = uni - uni-1
• Calculate spring compression:
ci = uni - uni-1
• Calculate spring forces:
Fi = ki ci
• Calculate spring forces:
Fi = ki ci
• Calculate resistance forces:
Ri = Rsi + Rdi
• Calculate resistance forces:
Ri = Rsi + Rdi
Force balance at a segmentForce balance at a segment
Acceleration: ai = (Fi + Wi – Ri – Fi+1) / mi
Velocity, vi, and Displacement, ui, from Integration
Acceleration: ai = (Fi + Wi – Ri – Fi+1) / mi
Velocity, vi, and Displacement, ui, from Integration
Mass mi
Force from upper spring, Fi
Force from lower spring, Fi+1
Resistance force, RiWeight, Wi
Set or Blow Count Calculation (a) Simplified: extrapolated toe displacement
Set or Blow Count Calculation (a) Simplified: extrapolated toe displacement
RR
SetSetFinal SetFinal Set
Maximum SetMaximum Set
QuakeQuake
RuRu
ExtrapolatedExtrapolated
CalculatedCalculated
(b) Blow Count Calculation by RSA(b) Blow Count Calculation by RSA
• Residual Stress Analysis is also called Multiple Blow Analysis
• Analyzes several blows consecutively with initial stresses, displacements from static state at end of previous blow
• Yields residual stresses in pile at end of blow; generally lower blow counts
• Residual Stress Analysis is also called Multiple Blow Analysis
• Analyzes several blows consecutively with initial stresses, displacements from static state at end of previous blow
• Yields residual stresses in pile at end of blow; generally lower blow counts
Blow Count Calculation(b) Residual Stress Analysis (RSA)
Blow Count Calculation(b) Residual Stress Analysis (RSA)
Set for 2 Blows
Convergence:Consecutive Blows
have same pile compression/sets
Static EquilibriumRam velocity
Dynamic analysis
Program Flow – Bearing GraphProgram Flow – Bearing Graph
Model hammer,driving system
and pile
• Pile stresses• Energy transfer• Pile velocitiesChoose first Ru
Calculate BlowCount
Distribute RuSet Soil Constants
Output
IncreaseRu?
Increase Ru Input
N
Y
Bearing Graph: Variable Capacity, One depthSI-Units; Clay and Sand Example; D19-42; HP 12x53;
Bearing Graph: Variable Capacity, One depthSI-Units; Clay and Sand Example; D19-42; HP 12x53;
The Inspectors’ Chart: One Capacity and One Depth – Stroke Variable
The Inspectors’ Chart: One Capacity and One Depth – Stroke Variable
21-Aug-2011GRL Engineers, Inc. GRLWEAP Version 2010Demo 3-Inspector's Chart - D16-32
21-Aug-2011GRL Engineers, Inc. GRLWEAP Version 2010Demo 3-Inspector's Chart - D16-32
Com
pre
ssiv
e S
tress
(M
Pa)
0
50
100
150
200
250
Tensi
on S
tress
(M
Pa)
0
50
100
150
200
250
Blow Count (blows/.25m)
Stroke
(m
)
40 80 120 160 200 240 2801.50
1.90
2.30
2.70
3.10
3.50
DELMAG D 16-32
Capacity 1600.0 kNRam Weight 15.66 kNEfficiency 0.800Pressure 9825 (99%) kPa
Helmet Weight 8.45 kNHammer Cushion 10535 kN/mmCOR of H.C. 0.800
Skin Quake 2.500 mmToe Quake 2.500 mmSkin Damping 0.259 sec/mToe Damping 0.500 sec/m
Pile LengthPile PenetrationPile Top Area
18.28 16.76
140.64
m m cm2
Pile ModelSkin FrictionDistribution
Res. Shaft = 30 %(Proportional)
Formulas and Wave EquationD19-42; HP 12x53; Clay and Sand
Formulas and Wave EquationD19-42; HP 12x53; Clay and Sand
0
500
1000
1500
2000
2500
3000
3500
4000
0 25 50 75 100 125 150 175 200
Blows/0.25 m
Cap
acit
y in
kN
Gates ENR GRLWEAP-Clay GRLWEAP-Sand
SUMMARYSUMMARY
• GRLWEAP simulates the what happens when a hammer strikes a pile
• GRLWEAP is based on Smith’s model with important extensions such as:– Realistic hammer models (ECH, OED, CED, VIB)
– Non-linear spring models for interfaces and slacks
– Alternative soil models
– Residual stress analysis
• GRLWEAP simulates the what happens when a hammer strikes a pile
• GRLWEAP is based on Smith’s model with important extensions such as:– Realistic hammer models (ECH, OED, CED, VIB)
– Non-linear spring models for interfaces and slacks
– Alternative soil models
– Residual stress analysis
SUMMARY, continuedSUMMARY, continued
• GRLWEAP , to simplify input offers four static pile analysis methods– Soil type based (ST)
– N-value and qu based (SA)
– φ and Su based (API)
– Cone Penetrometer based (CPT)
• GRLWEAP , to simplify input offers four static pile analysis methods– Soil type based (ST)
– N-value and qu based (SA)
– φ and Su based (API)
– Cone Penetrometer based (CPT)
Summary, continuedSummary, continued
• GRLWEAP models 3 distinctly different hammer models– External Combustion Hammer models
– Diesel hammer and pressure models
– Vibratory hammer model
• GRLWEAP works with 3 components in the driving system model– Hammer Cushion
– Helmet and Inserts
– Pile Cushion
• GRLWEAP models 3 distinctly different hammer models– External Combustion Hammer models
– Diesel hammer and pressure models
– Vibratory hammer model
• GRLWEAP works with 3 components in the driving system model– Hammer Cushion
– Helmet and Inserts
– Pile Cushion
Summary, continuedSummary, continued
• Basic Analysis options are the– Bearing Graph which relates 10 bearing capacity values
and stresses to blow count and
– Inspector’s Chart which relates required blow count to a hammer’s energy level (or stroke) for one capacity value.
• Basic Analysis options are the– Bearing Graph which relates 10 bearing capacity values
and stresses to blow count and
– Inspector’s Chart which relates required blow count to a hammer’s energy level (or stroke) for one capacity value.
End of GRLWEAP FundamentalsEnd of GRLWEAP Fundamentals
Questions?Questions?
Bearing Graph Workshop examplesBearing Graph Workshop examples
• Bearing Graph; CE Pipe driven by diesel hammer
• Bearing Graph and Inspector’s Chart for inclined/battered concrete pile
• Steel follower on concrete pile
• Bearing Graph; CE Pipe driven by diesel hammer
• Bearing Graph and Inspector’s Chart for inclined/battered concrete pile
• Steel follower on concrete pile
Diesel hammer bearing graphDiesel hammer bearing graph
Hammer: Find appropriate OE Diesel Find Associated Driving System
Pile: 12-3/4x3/8”; 325x10 mmClosed Ended PipeLength L = 50’ (15 m)
Soil: Sand
Desired working load 50 tonsSafety Concept: Wave Equation OnlyExpected Penetration LP = 45’ (14 m)
Hammer: Find appropriate OE Diesel Find Associated Driving System
Pile: 12-3/4x3/8”; 325x10 mmClosed Ended PipeLength L = 50’ (15 m)
Soil: Sand
Desired working load 50 tonsSafety Concept: Wave Equation OnlyExpected Penetration LP = 45’ (14 m)
LLLP
Continue: Concrete pile bearing graph and Inspector’s Chart
Continue: Concrete pile bearing graph and Inspector’s Chart
Hammer: Find appropriate ECHBoth Hammer and Driving System
Pile: PPSC - 24x24”; 610x610 mm;L = 80’ (24 m)
Soil: 10’ (3 m) Medium Clay 20’ (6 m) Stiff Silt30’ (9 m) Soft Clay30’ (9 m) Dense Sand
Water table: 15’ (4.5 m) below grade
Desired working load 150 tonsSafety Concept: Dynamic TestingExpected penetration 75’ (22.5 m)
Hammer: Find appropriate ECHBoth Hammer and Driving System
Pile: PPSC - 24x24”; 610x610 mm;L = 80’ (24 m)
Soil: 10’ (3 m) Medium Clay 20’ (6 m) Stiff Silt30’ (9 m) Soft Clay30’ (9 m) Dense Sand
Water table: 15’ (4.5 m) below grade
Desired working load 150 tonsSafety Concept: Dynamic TestingExpected penetration 75’ (22.5 m)
Steel Follower on Concrete Pile
Hammer: Up to 10 ton HydraulicHelmet/Hammer Cushion: see Tables
Follower: LF = 42.5’ - 12,800 mm18x2”-42’ - 450x50-12,650 mm pipe 18x18x6” - 500x500x150 mm plate
Pile Cushion:8” - 200 mm used plywood
Pile: PPC 20x20” LP = 50’500x500 mm LP = 15 m
Water Depth: 40’ - 12 mSoil Information: See CPT dataExpected pile penetration: LP = 43’ (13 m)Required working load: QD = 180 k (900 kN)
LC
Lp
Penetration
Water depth LF
LTLC
CPT data fileCPT data fileCPT data taken at xxx
Project: yyyyy
Depth (m) Tip Resistance (MN/m2) Sleeve Friction (MN/m2)
0.05 ‐0.08 0.0266 0.0%
0.1 5.73 0.0406 0.7%
0.15 17.37 0.0574 0.3%
0.2 13.19 0.0774 0.6%
0.25 11.73 0.1289 1.1%
0.3 9.79 0.1892 1.9%
0.35 7.06 0.2458 3.5%
0.4 4.45 0.248 5.6%
0.45 3.02 0.2052 6.8%
0.5 3.7 0.1558 4.2%
0.55 3.47 0.1801 5.2%
0.6 5.73 0.2192 3.8%
0.65 5.03 0.2397 4.8%
0.7 6.77 0.2507 3.7%
0.75 5.11 0.2658 5.2%
0.8 5.29 0.2532 4.8%
0.85 5.09 0.2424 4.8%
0.9 4.84 0.2156 4.5%
0.95 4.74 0.1811 3.8%
1 4.89 0.1596 3.3%
1.05 4.83 0.1498 3.1%
1.1 4.87 0.1324 2.7%
1.15 4.97 0.1052 2.1%
1.2 3.51 0.0971 2.8%
1.25 4.66 0.0891 1.9%
1.3 4.41 0.082 1.9%
1.35 4.36 0.0773 1.8%
1.4 4.49 0.0801 1.8%
1.45 5.37 0.0928 1.7%
Soil Types of CPTRobertson 1986
Soil Types of CPTRobertson 1986
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