large open ended pipe piles cylinder pile production · 3 a well designed driving system prevents...

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Large Diameter Open Ended Pipe Piles

Frank Rausche, GRL Engineers Day, 2015Frank Rausche, GRL Engineers Day, 2015

© 2014 Pile Dynamics, Inc.

Topics

• Pile Properties

• Cylinder and pipe pile details

• Damage potential

• The FHWA Synthesis

• Cylinder pile topics

• Plug formation, a study

• Very large pile example

• Summary

2 LDOEP, PDCA Professors’ Course, 2015

Steel Pile Properties• Rolled pipe diameters unlimited; spiral welded 10’

• Wall thickness 1” max for spiral weld


Cylinder Pile Production


Spinning, Post‐tensioning

Photos: courtesy Don Theobald, Gulf Coast Prestress


Moving and Installing

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Cylinder Pile Properties

• Sizes:– US: 36x5, 54x5, 66x6”

(910x130, 1370x130/150, 1680x150 mm)

– Other countries: 16, 20, 30” (400, 500, 750 mm) Concrete strengths:

– US: 6 to 8 ksi(42 – 55 MPa)

– Other countries: same or more


Driving systems


Add‐On

Stabbing Guide

Temp. Pile Top

Pile Stabbing


Static Bending Stresses

WH

Wp

Jacket Leg


Driving systems

•Leads which do not sway, bend piles

•Hammer cushion: man made material, uniformly worn

•Helmet: well fitting, evenly striking surface; skirt not to apply horizontal forces

•Pile cushion: plywood stacks, engineered and well assembled

Driving systems


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A well designed driving system prevents bending stresses,eccentricities

Photograph: Courtesy Massman Construction


ProblemsVertical Cracking Top Damage

Pile top damage due to:

• Uniform driving stresses plus prestress

• Hammer eccentricity and misalignment

• Limited effectiveness of hoop reinforcement

• Complex stress state at pile top


Pile top forces

Helmet lateral forceHelmet lateral force

Grout pressure

Strand anchoring forces

Cushion expansion force

Eccentric, misaligned driving forcesEccentric, misaligned driving forces

Non-uniformly worn cushion

Poorly fitting helmet

Concrete quality problemsConcrete quality problems


Pile top forces

Internal guide problems

Internal helmet lateral force

Internal helmet lateral force

Ouch

Non-uniformly worn cushion Non-uniform

cushion force


Tensile stress pile damage

• Low ram/pile weight ratios cause for high tension stresses both when driving is easy andwhen it is very hard

• Additional bending stresses particularly in battered pile driving

• High tension/compression stress cycles cause small tension cracks and eventually damage, particularly under water


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Recommendations for damage prevention

• Reduction of allowable driving stresses from 85% to 66% of strength minus prestress

• Monitoring of driving stresses

• Well engineered driving system

• Well aligned hammer ‐ pile to prevent bending

• Careful grouting and prestressing

• High quality concrete and curing


Bending / Local Stress concentrations

… due to

• Hammer Weight

• Pile Batter

• Barge/crane/lead motion

add to

• Driving and pre‐stress, post‐tensioning stresses

also

• Non‐uniform soil resistance adds to unpredictable additional stresses

Ouch


The Synthesis


Some relevant statements

• Large diameter open ended piles (LDOEPs) are steel or prestressed concrete cylinders 36” or larger in diameter which can provide large axial and lateral resistance even in relatively poor soil conditions

• Load and Resistance Factor Design (LRFD) methods for piles were calibrated using piles with a diameter of 24” or less

• Recent or current projects with LDOEPs San Francisco –Oakland Bay Bridge, Woodrow Wilson Bridge, Tappan Zee Bridge, Kentucky Lakes Bridge, .. in New York which is currently under construction


SynthesisResults


SynthesisResults


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SynthesisResults


Synthesis Results


Synthesis Results


Synthesis Results


Synthesis results

McVay 2004

66” dia OE Cylinder pileDetermined critical g‐level of 15 g’s for plug slipping

Static: 1962 kipsR‐total CAPWAP – restrike with 0 set and no superposition:

1266 kips

(Note: Superpostion uses end bearing from EOD and Shaft resistance from BOR)


Synthesis resultsAlaska DOT – 12 to 48” dia piles

Developed a design method based on CAPWAP results.

The proposed relationships were used to predict pile resistance on a project with 29 monitored piles driven into silt-rich deltaic deposits.

Dickenson reported “Overall, the agreement between the predictions and the CAPWAP results was good to excellent, and the proposed method provided much more reliable ranges of estimated pile resistance than obtained using widely-adopted, standard of practice procedures.”


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Synthesis results

A Comparison of Dynamic and Static Pile Test Results (OTC, Stevens 2013):

48” dia OEPipe Piles at 40’ and 65’ depth Uplift Static: 1180 and 2530 kips

R‐shaft CAPWAP: 1290 and 2530 kips

78” dia OEPipe Piles at 110’Uplift Static: 5875 kips

R‐shaft CAPWAP: 5930 kips (extrapolated to 53 days using pore water pressure measurements)


Synthesis resultsKentucky Lakes, Terracon

48 and 72” dia OEpipe piles with 1 to 2” wall thickness48” plug models after Paikowsky


Synthesis resultsKentucky Lakes, Terracon


Synthesis results: Kentucky Lakes


Synthesis results: Kentucky Lakes

• For the dynamic records where radiation damping was applied, the modelgenerally resulted in a significantly better signal match quality, indicating theradiation damping allows CAPWAP to better model the signals recorded by thedynamic pile testing equipment.

• The pile resistances calculated with CAPWAP using the radiation dampingmodel also generally produced higher end bearing resistance values than theCAPWAP models without the radiation damping. It appears that the radiationdamping model is better suited for estimating the end bearing component of thepiles when less pile set is experienced per hammer blow. This is the case whenthe constrictor plates are engaged on the dense granular soils.

• Wave equation analyses indicated that plugged piles would have high stresses.Additionally there was concern that localized high stresses might be encountereddue to the presence of the chert. Testing on the piles typically did not approachas high values as expected.


US 378 Bridge over Pee Dee River (South

Carolina) S&ME

Two 54” diacylinder piles

To monitor the formation of a plug in the interior of the pile, a simple device called apile plug monitoring device (PPMD) was constructed. The PPMD consisted of leadweights attached to a 100 foot fiberglass measuring tape. The weights would fall to thetop of the soil column inside of the piles, allowing the distance to the soil to becomputed. Access to the interior of the pile was made through a vent hole near the topof the pile. The PPMDs were read intermittently throughout test pile installation. The data showed that soil was rising inside both piles during driving, indicating that disturbed soil and water was accumulating in the pile rather than a pile plug forming and traveling down with the pile.

Synthesis results


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Synthesis results

US 378 Bridge over Pee Dee River (South

Carolina) S&ME

!

!


Longitudinal cracks

Potential causes:• Poisson’s effect and/or insufficient hoop reinforcement

– (may not be a problem)

• complex stress state at pile top or pile bottom• concrete and/or manufacturing defects• internal hydrostatic water pressure

– (provide water escape hole)

• internal excess soil or pore water pressure– (wash out plug, bail out water!)

• internal dynamic air/water pressure

CANNOT BE DETECTED BY PDA


Static Plugging

Internal Friction (from arching?) on plug

Internal friction on pipe

End Bearing

Internal soil column

Pile wall


Dynamic Plugging?

Internal Friction on plug

Internal friction on pipe

End Bearing

Inertia force

Soil column

Pile wall


Dynamic Considerations:Plug inertia vs internal resistance

Assuming a plug length equal to 1, 3 and 5 diameter pile diameters

Assuming 100 g’s steel acceleration

The graph shows internal friction and inertia (no end bearing) 0

1000

2000

3000

4000

5000

12 24 36 48 60 72 84 96

Iner

tia

or

Inte

rnal

Res

ista

nce

(k

ips)

Diameter (Inches)

1D Plug Inertia

3D Plug Inertia

5D Plug Inertia

1D Plug Ri

3D Plug Ri

5D Plug Ri

Conclusion: under these VERY simplified circumstances a plug will slip if the diameter is more than ~40 inches


Unplugged pile toe accelerationConcrete cylinder pile

Figure 3: Relative Toe Acceleration for Unplugged Cylinder Piles

30

40

50

60

70

80

90

100

40% 50% 60% 70% 80% 90%

Analyzed Stroke Relative to Rated Stroke

To

e A

cce

lera

tio

n (

g's

)

Hydraulic 8" Cushion



Diesel 8" Cushion

Diesel 12" Cushion

Diesel 15" Cushion


8

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

12000

0 10 20 30 40 50

Time (ms)

Fo

rce

(kN

)

Inertia Force

Toe Resistance on Plug

Total

Lp

qu

fs

Soil inertia and toe resistance on plug

Lpfs

Fi

qtoe


Loss of Resistance Due to Pile DrivingLoss of Resistance Due to Pile Driving

• Sand porewater pressure changes

• Liquefaction

• Clay remolding, thixotrophy

• Other?

• Arching in granular soils• not during driving at toe: reduced end bearing

• During driving at shaft: reduced friction


Loss of friction due to pile lateral motions

Pile


Pile

Loss of friction due to pile lateral motions


Loss of friction due to arching

Soil-pile interface with reduced effective

stresses

Pile

Compressed, higher density soil


Friction fatigue considers that the SRD is equal to the LTSR at the pile toe and decreases exponentially above the toe (loss depends on the distance from the toe)

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Dep

th b

elo

w m

ud

line

in m

Resistance per1 m segment in kN

Rinitial (LTSR)

Rresidual (SRD)


Friction Fatigue: Loss of resistance

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0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Dep

th b

elo

w m

ud

line

in m


Rinitial (LTSR)

Rresidual (SRD)


0

10

20

30

40

50

60

70

80

90

100

0 200 400 600

Dep

th b

elo

w m

ud

line

in m


Rinitial (LTSR)

Rresidual (SRD)



• Friction fatigue considers that the SRD is equal to the LTSR at the pile toe and decreases exponentially above the toe (loss depends on the distance from the toe)

• In contrast, the standard GRLWEAP approach assumes full loss of resistance in a particular soil layer.

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500

Dep

th b

elo

w m

ud

line

in m


25 m depth 50 m depth

75 m Depth



Rinitial (LTSR)

Rresidual (SRD) 0

10

20

30

40

50

60

70

80

0 0.2 0.4 0.6 0.8 1 1.2

Dis

tan

ce f

rom

Bo

tto

m

Long Term Capacity Multiplier

Example: fs=5, Ll=50, fo=0.001; fL= 0.05

fL

Ll

• Resistance Ratio, fs (say 5?)fs = Rinitial/Rresidual

• Degradation distance, Ll (Limit Length, 20 to 150 m)

• Undegraded distance, fL say 0.05)

• Exponent for degradation shape, fo (say 0.001)

See Alm and Hamre, 2001. Soil model for pile driveability based on CPT interpretation. Proc. 15th Int Conf. on Soil Mechanics and Geotechnical Engineering, Istanbul


GRLWEAP Friction Fatigue Approach

In Preparation of an improved GRLWEAP/CAPWAP model let us consider what we must calculate:

Displacement of steel and plug Velocity of steel and plug

Unknowns to be determined: fste, qste

fsti, qsti

rst, qst

rpl, qp

plus damping

External and Internal Pipe Friction, fsti, qsti,fste, qste

rP, qp,t

Plug Wt

Steel

Plug

Plug Inertia

rt,St qt

Plug modeling


Simplified model: single plug mass Unknowns to be determined: fste, qste, fsti, qsti, rpl, qp plus damping

Pipe Pile Steel onlyPlug

Wit Full End Bearing

Acceleration from GW - easy drivingDiameter inch D 18Wall thickness inch t 0.5Area in^2 A 27.489Pile segment length inch dL 40Soil plug length inch dPl 72.000Segment weight above toe segment k w1 0.313mass above last pile segment k/f/s2 m1 0.001weight of last pile segment k w2 0.313mass of last pile segment k/f/s2 m2 0.001weight of plug k wp 0.945mass of plug k/f/s2 mp 0.002internal limit friction F-int. ksf 5.000internal limit friction F-int. kips 133.518unit res against steel ru-toe-s ksf 250.000unit res against steel rutoe-s ksi 1.736Steel toe resistance ult Rutoe-s k 47.724unit res against plug ru-toe-p ksf 125.000unit res against plug rutoe-p ksi 0.868Soil toe resistance Rutoe-p k 196.931q steel toe qs inch 0.100q soil plug qp inch 0.283Rel. plug length Lplug diameters 4.000q internal friction qfi inch 0.100Note, this model uses unloading =loading quake as per GRLWEAP


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Example 18 inch pile

Pile is rigidly linked to plug –displacements are the same.

Easy driving record

-200

0

200

0 5 10 15 20 25 30

Vel

in

inch

/s

ms

v steel

v steel

-0.4

0.1

0.6

1.1

0 5 10 15 20 25 30Dis

pl.

in in

ches

Time in ms

d steel

d steel

-500

0

500

0 5 10 15 20 25 30

Acc

eler

atio

n in

g's

Time in ms

a steel

a steel

0

50

100

150

200

250

300

0 5 10 15 20 25 30

forc

e -

kips

Time in ms

Plug rigidly linked to steel

R steel Rplug-no slip Rtotal-no slip

INPUT - Easy driving record


Plug is linked to steel pipe with an elasto‐plastic spring (R‐int, q‐int)

-300

-200

-100

0

100

200

0 5 10 15 20 25 30

Vel

in

inch

/s

msv steel v plug

-0.4

0.1

0.6

1.1

0 5 10 15 20 25 30Dis

pl.

in in

ches

Time in msd steel d plug

-400

-200

0

200

400

600

0 5 10 15 20 25 30

Acc

eler

atio

n in

g's

Time in msa steel a plug

-300

-200

-100

0

100

200

300

0 5 10 15 20 25 30

forc

e -

kips

time - ms

All forces

R steel F-int Rplug Inertia

INPUT - Easy driving record

Example 18 inch pilePile is rigidly linked to plug –displacements are the same.

0

20

40

60

80

100

120

140

160

180

200

3 8 13 18 23 28 33

forc

e -

kips

Time in ms

Rigidly linked plug

R steel Rplug-no slip Rtotal-no slip

-1000

0

1000

3 8 13 18 23

Acc

eler

atio

n in

g'

s

Time in ms

a steel

a steel

-200

3 8 13 18 23inch

/s

ms

v steel

v steel

-0.2

3 8 13 18 23inch

es

ms

d steel

d steel

INPUT - Hard driving record



-500

0

500

3 8 13 18 23

Acc

eler

atio

n in

g'

s


-200

0

200

3 8 13 18 23inch

/s

msv steel v plug

-0.2

-0.1

0

0.1

0.2

3 8 13 18 23inch

es

ms

d steel d plug

-150

-100

-50

0

50

100

150

200

3 8 13 18 23forc

e -

kips

time - ms

R steel F-int Rplug Inertia




-500

0

500

3 8 13 18 23

Acc

eler

atio

n in

g'

s


-200

0

200

3 8 13 18 23inch

/s

msv steel v plug

-0.2

-0.1

0

0.1

0.2

3 8 13 18 23inch

es

ms

d steel d plug


-150

-100

-50

0

50

100

150

200

3 8 13 18 23forc

e -

kips

time - ms

R steel F-int Rplug F-pile Rs+Rp

Conclusion from simplified plug model

• The study clearly shows that the full activation of the toe resistance against the plug is as important as plug slippage when attempting to mobilize and calculate full resistance

• The model has to consider

– the internal friction on plug and pile

– the plug compressibility and mass

– different quakes and unit resistance values for annulus when not plugging and unit toe resistance for plugged analysis


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21m dia Steel; APE Octagon; Photo Galerie

A Word about Very Large Pipes and Vibratory Analysis


4 APE 600B12x0.25 m dia concrete shell


GRLWEAP Calculated of Rate of Penetration

Yangtze Caisson:

12x.25 m concrete pipe, 25 m long

4 APE 4B hammers (683 kg m, 20 Hz, 3000 kW); 8 clamps + beams

Clay, silty Sand; N at most 3

Shaft resistance (inside and out) 10 kPa

Analyzed at 80% and 100%

Toe resistance 90 kPa


GRLWEAP Calculated of Rate of Penetration

Yangtze Caisson

0

2

4

6

8

10

12

0 50 100 150 200

Penetration Speed - mm/s

Dep

th in

m

80% Shaft Res: 30 s 100% Shaft Res: 66 s


Thank You

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