design and execution of jack-in piles in malaysia” at the 1-day

G&P Geotechnics Sdn Bhd

Ir. Chow Chee MengG&P Geotechnics Sdn Bhd (Malaysia)

31st August 2015

DESIGN AND EXECUTION OF JACK-IN PILES IN MALAYSIA

One Day Seminar on

JACK-IN FOUNDATION PILES –

GOOD PRACTICES AND ITS APPLICATIONS

Organized by Geotechnical Society of Singapore (GEOSS)

Bored Pile Contractors/Engineers working with Bored Pile

Contractors?

PLEASE RAISE YOUR HAND!!!

Jack-in Pile Contractors/Engineers working with Jack-in Pile

Contractors?


Engineering consultants / Government engineers?


SCENARIO A SCENARIO B

PROCEED WITH PRESENTATION!

Are we a victim of confirmation bias on selection of foundation system?

In psychology and cognitive science, confirmation bias (or confirmatory bias) is a tendency to search for or interpret information in a way that

confirms one's preconceptions, leading to statistical errors.

Good girl?

Good academic results?

Good wife material?

What is our immediate opinion?

We like this picture more!!!


INTRODUCTION

Jack-in pile has been adopted in Malaysia since early 1990s

Currently, 600mm diameter spun pile with working load up to 3000kN adopted for high-rise developments up to 45-storeys


HIGH CAPACITY JACK-IN PILE MACHINE


HIGH CAPACITY JACK-IN MACHINE

•Maximum jack-in force up to 7000kN

•Width of machine up to 13.5m

•Required clearance for piling works: 5.5m to 6.9m (centre jacking)

•Clearance can be reduced to 1.5m to 2.0m for side jacking but maximum jack-in force reduced to approx. 3500kN


Typical schematic of high capacity jack-in pile machine


SMALLER CAPACITY JACK-IN PILE MACHINE


Maximum Jack-in Force = 700kNSize = 4.8m x 3.6m


Maximum Jack-in Force = 1500kNSize = 6.6m x 5.0m


PROS & CONS

PROS:

Low noise and vibration

Faster construction rates (vs. bored piles)

Cleaner sites (vs. bored piles)

Relatively clean site compared to bored piles!


CONS

Strong and flat piling platform required

Larger working area required (vs. driven piles/bored piles)

Limited pile size (vs. bored piles)

Unable to go through intermittent hard layers/boulders (vs. bored piles)

PROS & CONS


Comparisons JACK-IN PILE DRIVEN PILE BORED

PILE Cyclic load during pile installation

Less cycles compared to driven pile

Number of cycles more especially

for long piles

N.A.

Termination criteria

Static (pseudo) load imposed onto

pile head

Dynamic load imposed onto pile

head

Based on SI information

Variables affecting efficiency of load transfer during pile installation

1. Hydraulic system of jacks

2. Calibration of pressure gauge

1. Efficiency of hammer, helmet, etc.

2. Hammer drop height

3. Cushion properties

4. Eccentricity of pile/hammer

N.A.

Verification of geotechnical capacity during installation

Relatively straightforward as loading rate is

slow

Indirect verification based

on dynamic analysis. Often

unreliable.

N.A.

Probability of pile damage during installation

Low High Depends on workmanship


GEOTECHNICAL CAPACITY OF PILES



Ultimate shaft resistance,fsu = Ksu x SPT-N (in kPa)

Ultimate base resistance,fbu = Kbu x SPT-N (in kPa)

Typically,Ksu = 2.5 to 3.0Kbu = 200 to 400 (clay to sand)


Design based on driven piles experience

Valid for jack-in pile design?



BEHAVIOUR OF JACK-IN PILES



Rankine Lecture by Prof. Mark Randolph (2003):

•Bored piles – zero residual pressures

•End-bearing can only be mobilised at relatively large displacement


Driven and jacked in piles - significant residual pressures are locked in at the pile base during installation

Higher end-bearing can be mobilised at working load



White & Lehane (2004):

Greater number of cycles during pile installation

larger reduction in shaft friction



Reduction in shaft

resistance!!!

White & Lehane, 2004


Deeks, White & Bolton (2005):

The measured jacking force during installation indicates plunging capacity of the pile



Jacked piles have a high base stiffness

Stiffness of jacked piles> 2 times stiffness of driven piles> 10 times stiffness of bored piles



CASE HISTORIES


• Starting of Jack-In Pile system using large size pile in Malaysia (Year 1999)

• Installed through municipal dumping site with mine tailings overlying Karstic Kuala Lumpur Limestone bedrock.

• Adopted 450mm Spun Pile with Working Load of 1500kN

1st Site


1st Site

GRANITE FORMATIONCASE HISTORIES


Four sites in Kuala Lumpur and Selangor, Malaysia :

•Site A: 31-storey apartment•Site B: 45-storey apartment•Site C: 40 to 43-storey apartment•Site D: 15-storey apartment

Case Histories


Case Histories (Sites A to D)

• Pile size: 400mm to 600mm

• Pile working load: 1520kN to 3000kN

• All piles generally jacked to 2.0 times working load with holding time of 30-seconds (2 cycles)


• Silty SAND / sandy SILT overlying Granite Formation (weathered granite)

• Boulders encountered- Some piles installed after preboring

Case Histories (Sites A to D)


Site A


Site A

Granite Formation


Site C

Target Completion Mid 2011


Site D


Site B


Pile toe at hard weathered granite layer

Site B


Total of 22 static load tests carried out for the 4 sites

All piles selected for testing achieved minimum 2 times working load!!!

(No pile failed!)•No signs of plunging failure of pile•Settlement at working load: 3.04 – 9.88mm•Settlement at 2*WL: 6.96 – 22.22mm

Static Load Tests


Static Load Tests

• Pile as short as 6.5m tested with settlement at working load and 2*WL of 8.32mm and 19.73mm respectively

• Pile performance are satisfactory for piles where preboring have been carried out

• Termination criterion adopted adequate


Preboring through boulders

Boulders exposed after

preboring


Static Load TestsSite B

0 1 2 3 4 5 6 7 8 9 10111213141516171819202122PILE TOP SETTLEMENT (mm)

0200400600800

1000120014001600180020002200240026002800300032003400360038004000420044004600

APP

LIED

LO

AD

(kN

)

500mm Spun Pile, Pile length = 6.5m


Static Load TestsSite B


Static Load Tests


Termination criterion for jack-in piles in weathered granite:

“Jack the pile to 2.0 times of the design load for a minimum of two cycles. The corresponding pressure has to be held for minimum 30 seconds with settlement not exceeding 2mm”

Termination Criteria


Instrumented test piles Site C (3 Nos.)Site D (2 Nos.)

Piles instrumented using the Global Strain Extensometer method

Mobilised Resistance


Mobilised (Shaft) Resistance

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20DISPLACEMENT (mm)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150M

OB

ILIS

ED S

KIN

FR

ICTI

ON

(kN

/m2 )

0.5m to 10.7m10.7m to 20.9m

600mm Spun Pile, Pile length = 21.4m(Nearest borehole, BH-20)

Site C

fsu = 5 x SPT-N (in kPa)

- conservative!!!


Mobilised (Base) Resistance

0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

0500

10001500200025003000350040004500500055006000650070007500800085009000

MO

BIL

ISED

EN

D-B

EARI

NG

RES

ISTA

NCE

(kN

/m2 )


End-bearing not fully mobilised

Stiff end bearing response observed –

end-bearing mobilized with small toe displacement

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20DISPLACEMENT (mm)

0

25

50

75

100

125

150

175

200

225

250

275

300M

OB

ILIS

ED S

KIN

FR

ICTI

ON

(kN

/m2 )

0.5m to 5.75m5.75m to 14.75m14.75m to 20.75m20.75m to 23.0m





- conservative!!!



0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

0500

100015002000250030003500400045005000550060006500700075008000

MO

BIL

ISED

EN

D-B

EAR

ING

RES

ISTA

NC

E (k

N/m

2 )






0 2 4 6 8 10 12 14 16 18 20 22DISPLACEMENT (mm)

0

25

50

75

100

125

150

175

200

225

250

275

300M

OB

ILIS

ED S

KIN

FR

ICTI

ON

(kN

/m2 )

0.82m to 6.53m6.53m to 17.43m17.43m to 26.43m26.43m to 31.43m31.43m to 33.93m



- conservative!!!

Site D



0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

020406080

100120140160180200220240260280300320340360380400

MO

BIL

ISED

EN

D-B

EAR

ING

RES

ISTA

NC

E (k

N/m

2 )





LIMESTONE FORMATIONCASE HISTORIES


Static Load Tests

0 5 10 15 20 25 30PILE TOP SETTLEMENT (mm)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

Legends:1st Cycle2nd Cycle3rd Cycle

Load-Settlement Curve for Pile Static Load Test

500mm Spun Pile, Pile length = 31.5m

500mm diameter spun pile

Pile working load = 2,300kN

1*WL

8mm

2*WL

16.5mm

3*WL

28.5mm



0 5 10 15 20 25 30DISPLACEMENT (mm)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

MO

BILI

SED

SH

AFT

FRIC

TIO

N (k

N/m

2 )

Legends:1.0m to 9.0m9.0m to 19.5m19.5m to 27.5m27.5m to 31.0m

Mobilised Shaft Friction (Sunway)

500mm Spun Pile, Pile length = 31.5m(Nearest borehole, ABH-4)


- conservative!!!



0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

6500

7000

Mobilised End-Bearing Resistance (Sunway)

500mm Spun Pile, Pile length = 31.5m(Nearest borehole, ABH-4)




ALLUVIAL DEPOSITSCASE HISTORIES

AP

PLI

ED

LO

AD

, kN


Static Load Tests



1*WL

11mm

2*WL

23mm

3*WL

44mm

Sudden structural failure of pile head!

MO

BIL

ISE

D S

HA

FT F

RIC

TIO

N (k

N/m

2 )




- conservative!!!

0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

Mobilised End-Bearing Resistance (GEMA)








SUMMARY


• Termination criterion of jack to 2 times pile working load and holding time of 30-seconds (two to three cycles) with settlement not exceeding 2mm is satisfactory

• Ultimate pile capacity is a function of jack-in force during pile installation (consistent with other findings, e.g. Deeks et al., 2005)

SUMMARY


• Traditional correlations of skin friction based on driven piles (e.g. fs = 2.5*SPT-N) is too conservative for jack-in piles

• Conservative estimate based on instrumented test results:- Ultimate skin friction, fs ~ 5*SPT-N (expected to be even higher – to be verified with more test results)

SUMMARY


SUMMARY

•Jack-in piles demonstrates higher skin friction possibly due to:

- Less disturbance during installation -friction fatigue phenomenon (e.g. White & Lehane, 2004)

- Locked-in pressure (residual pressure) effect (e.g. Randolph, 2003)


SUMMARY

•Jack-in piles demonstrates stiffer end bearing response

- Consistent with Deeks, White & Bolton (2005):

Stiffness of jacked piles> 2 times stiffness of driven piles> 10 times stiffness of bored piles

METASEDIMENTARY FORMATION

CASE HISTORIES


NusajayaPROPOSED 4 BLOCKS OF 12 & 24 – STOREY RESIDENTIAL APARTMENTS (488 UNITS) AT PHASE C1B, EAST LEDANG, JOHOR


Static Load Tests



Prebored depth = 9.0mPile length = 9.5m

Mobilisation of end-bearing?



fsu 2 x SPT-N (in kPa) of original subsoil



End-bearing less stiff compared to behavior observed in granite formation, etc. Possibly due to

behavior of weathered sandstone/siltsone.

End-bearing mobilized still relatively high compared to

bored piles/driven piles!


Puteri HarbourPROPOSED MIXED DEVELOPMENT @ PUTERI HARBOUR ON LOT CS2, COMMERCIAL SOUTH, NUSAJAYA, JOHOR3 blocks up to 35-storey high


Puteri Harbour

Traders Hotel

CS2 – Jack-in Piles

CS1 – Driven Piles


CS-2Jack-in Piles


Static Load Tests



1*WL

5.5mm

2*WL

15mm

Maximum test load achieved 8,000kN (2.7*WL)



Prebored length = 13.0mInstalled pile length = 15.0m

Significant shaft resistance mobilised even after preboringfsu = 5 x SPT-N (in kPa)????






bored piles/driven piles!


CS-1Driven Piles


Static Load Tests

400mm x 400mm RC square pile


1*WL

8.5mm

2*WL

20mm





Shaft resistance still influenced by original subsoil but magnitude less compared to jack-in pilesfsu = 2 x SPT-N (in kPa)????






bored piles!


Static Load Tests

450mm x 450mm RC square pile


1*WL

12mm





Shaft resistance influenced by original subsoil but significant less compared to jack-in pilesfsu = 2 x SPT-N (in kPa)????


Mobilised (Base) ResistanceEnd-bearing less stiff compared to behavior observed in granite formation, etc. Possibly due to


End-bearing affected by softer layer beneath toe?

Re-testing carried out on another pile with deeper

preboring length of 15m (pile length 18m) but still failed at

1.3*WL


SUMMARY


• Noticeable differences in jack-in pile behavior between granite/sandy soil vs. metasedimentary formation (sandstone/siltsone) with preboring

• End-bearing response stiffer in granite/sandy soil without preboring

• End-bearing response for jack-in piles in metasedimentary formation still stiffer compared to bored piles and driven piles

SUMMARY


0 1 2 3 4 5 6 7 8 9 10DISPLACEMENT (mm)

0500

100015002000250030003500400045005000550060006500700075008000

MO

BIL

ISED

EN

D-B

EAR

ING

RES

ISTA

NC

E (k

N/m

2 )

Granite formation(without preboring)

Metasedimentary formation(with preboring)


• Due to heterogeneous characteristics of metasedimentary formation and effect of preboring, end-bearing resistance highly variable. Conservative assumptions of ultimate end-bearing resistance of 10,000kPa for pile design in metasedimentary formation with preboring– As opposed to granite formation where pile

capacity is a function of jack-in force during pile installation

SUMMARY


• Any difference between jack-in pile and driven pile?

• Results indicate shaft friction for jack-in pile higher than driven pile (approximately 2 times higher)

• Possibly affected by bigger prebored zone in driven square piles

SUMMARY


Jack-in Pile


Significant shaft resistance mobilised even after preboringfsu = 5 x SPT-N (in kPa)????


Driven Pile


Shaft resistance influenced by original subsoil but significant less compared to jack-in pilesfsu = 2 x SPT-N (in kPa)????


• Shaft friction after preboring very low or negligible?

– Shaft friction is a function of original subsoil even after preboring

– For jack-in pile, mobilized shaft friction still significant and fs ranges from 2*SPT-N to 5*SPT-N!

SUMMARY


CONCLUSION


• Jack-in pile can be an economical foundation system for high-rise buildings

• Behaviour of jack-in piles and driven piles different

– Pile length for driven piles would have to be longer to mobilize similar geotechnical capacity due to lower shaft friction and lower base stiffness

– Shaft friction mobilized in granite formation/sandy subsoil for jack-in pile can be conservatively assumed to be 5*SPT-N (likely to be higher subject to further test results)

CONCLUSION


• For granite formation/sandy subsoil:– Termination criterion of jack to 2 times pile

working load and holding time of 30-seconds (two to three cycles) with settlement not exceeding 2mm is satisfactory

– Ultimate pile capacity is a function of jack-in force during pile installation (consistent with other findings, e.g. Deeks et al., 2005)

CONCLUSION


• For metasedimentary formation:– Due to heterogeneous characteristics of

metasedimentary formation and effect of preboring, end-bearing resistance highly variable. Geotechnical capacity checks should be carried out with ultimate end-bearing resistance of 10,000kPa

• Significant shaft resistance is still mobilized after preboring for jack-in pile and it is still a function of original subsoil

CONCLUSION


• Jack-in Piles not suitable in soft ground?

• Jack-in Piles not suitable in limestone?

• Jack-in Piles not suitable for high-rise?

• Jack-in Piles less reliable compared to bored piles?

QUESTIONS TO PONDER


THANK YOU

design and execution of jack-in piles in malaysia” at the 1-day

Documents