Statnamic Pile Load Testing Flip Hoefsloot, Fugro The Netherlands January 2010

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Contents Menu Load Testing Methods Description Statnamic Video of Test Application Interpretation Guidelines Conclusion

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Load Testing Methods

STATIC

High High pressure pressuregas gas

100 % Load Displacement

STATNAMIC

DYNAMIC

5-10% 1-2 %

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Strain

Load

Acceleration

Displacement

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Description Stanamic

1

3

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2

A = Pile B = Load cell C = Cylinder D = Piston with chamber E = Platform F = Silencer G = Reaction mass H = Gravel Container I = Gravel J = Laser K = Laser beam L = Laser sensor

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Description Stanamic

Fugro

Clients Word wide

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Profound

Knowledge and experience Statnamic (Peter Middendorp)

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Description Stanamic Hydraulic Catching Mechanism Containers filled with local material (gravel or equivalent) 4 test a day Simple inspection ignition system Transport on one trailer

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Description Stanamic Equipment: 80 tons reaction mass 7 trailers for transport 2 to 3 days a test one cycle of testing

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Video of Test

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Application, Static Load Test Advantages: •Static behaviour •Separation of: •End Bearing •Shaft Friction

Disadvantages: •Cost •Selection of Test Piles

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Application, Dynamic Load Test Advantages: •Low Cost •Test on all Piles

Disadvantages: •Dynamic Pile-Soil behaviour •High stresses in Pile •Requires advanced analyzing Techniques •Applicable only for Steel Pipe Piles

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Application, Statnamic Load Test Advantages:

Relatively low Cost Free selection of test Piles

Disadvantages:

Difficult to determine Bearing Capacity Difficult to distinguish between End Bearing and Shaft Friction

Application:

Re-use of existing Piles Load-Settlement behaviour

Condition:

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10 ≤

Tf L / cp

≤ 1000

Tf L cp

Duration of rapid load pile length stress wave velocity test pile

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Interpretation Fstn

u

Fstn Fst u v a m C

M

F stn

= statnamic force, measured = static resistance = displacement, measured = du/dt = d2u/dt2 = pile mass = damping coefficient

m k

C

Fstn (t ) = Fst (t ) + m ⋅ a(t ) + C ⋅ v(t ) Date

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Interpretation Time [ms] 0

50

100

150

200

250

300

Load [MN]

20 15

Load Cell 10 5 0

Time [ms]

Displacement [mm]

0

50

100

150

200

250

300

0 10 20 30 40 50

Laser Sensor Accelerometer

60 Date

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Interpretation Load [MN] 0

5

10

15

20

Displacement [mm] .

0 10 20 30 40 Fstn(t) 50

Fstatic(t) UP

60

Fst (t ) = Fstn (t ) − m ⋅ a (t ) − C ⋅ v(t ) Estimated damping parameter C (hyperbolic curve) Date

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Interpretation Dynamic Analysis, PLAXIS Simplified input of dynamics boundary conditions with Microsoft notepad

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Interpretation Dynamic Analysis, PLAXIS Calibration model with static behaviour Average damping parameter selected based on hyperbolic curve Statnamic Test

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Numerical Simulation PLAXIS

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Interpretation Load [MN] 0

5

10

15

20

25

0

Extrapolation according to Middendorp and Bakker

20

Displacement [mm] .

40 60

Correction for “rate effects”:

80

Undrained behaviour Fy [kN/rad]

100

-5000

120

-4000

Undrained analysis

160

Fstn(t) Fu(t)

180

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-2000

Drained analysis -1000

Hyperbolic F=u/(p+q.u) Hyperbolic F=Fref(u/uref)^0.5

200

“Rate effect”

-3000

140

0 0

0,05

0,10

0,15

0,20

|U| [m]

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Interpretation Bochum, Pfahl 57 STN Cyclic Load Displacement Diagram 0

Cycle 1

Cycle 2

Cycle 3

5

Bochum, Pfahl 57

10

0

15

20

25

30 0.0

Cycle 1 Cycle 2 Hyp. Appr. Static Long Term

Cycle 3

Hyp. Appr. Static Quick

5

Displacement [mm]

Displacement [mm]

STN Static Cyclic Load Displacement Diagram

0.5

1.0

10

15

20

1.5 2.0 Load [MN]

2.5

3.0

3.5

25

30 0.0

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0.5

1.0

1.5 2.0 Load [MN]

2.5

3.0

3.5

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Guidelines The Netherlands
CUR-comittee H410 “Rapid load tests”
goal: preparation European Codes
Fugro is member (Maarten Profittlich)

European Codes
Draft standard Rapid Load Testing procedure
Working group 4 of TC 341
(Testing of geotechnical structures; Testing of piles: rapid load testing (reference EN-ISO 22477-# version: 3.3, 23 April 2008)


Guideline on the interpretation of Rapid Load test on piles
7 November 2008

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Conclusion Statnamic provides alternative in case
Static load tests are not feasible
Re-use of existing Piles
Determine Load-Settlement behaviour

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Thank You

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