Statnamic Pile

Flip Hoefsloot, Fugro The Netherlands January 2010

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

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STATIC HighHigh 100 % pressurepressure gas gas

Load Displacement STATNAMIC DYNAMIC 5-10% 1-2 %

Strain Load Acceleration Displacement

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A = Pile B = Load cell C = Cylinder D = Piston with chamber E = Platform F = Silencer 1 2 G = Reaction mass H = Container I = Gravel J = Laser K = Laser beam L = Laser sensor 3 4

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Clients Knowledge and experience Word wide Statnamic (Peter Middendorp)

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

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Advantages: •Static behaviour •Separation of: •End Bearing •Shaft

Disadvantages: •Cost •Selection of Test Piles

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Advantages: •Low Cost •Test on all Piles

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

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Advantages: Relatively low Cost Free selection of test Piles

Disadvantages: Difficult to determine Difficult to distinguish between End Bearing and Shaft Friction

Application: Re-use of existing Piles Load-Settlement behaviour

Condition: T Duration of rapid load Tf f 10 ≤ ≤1000 L pile length c stress wave velocity test pile L/cp p

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Fstn Fstn = statnamic force, measured Fst = static resistance u = displacement, measured M v = du/dt u a = d 2u/dt 2 F stn m = pile mass C = damping coefficient

m

k C

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

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Time [ms] 0 50 100 150 200 250 300 20

15 Load Cell 10

Load[MN] 5

0

Time [ms]

0 50 100 150 200 250 300 0 10 20 30 Laser Sensor 40 Accelerometer 50 Displacement[mm] 60

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Load [MN] 0 5 10 15 20 0

10

20

30

40 Fstn(t) Displacement [mm] . Displacement[mm] 50 Fstatic(t) UP 60 = − ⋅ − ⋅ Fst (t) Fstn (t) m a(t) C v(t)

Estimated damping parameter C (hyperbolic curve)

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Dynamic Analysis,

Simplified input of dynamics boundary conditions with Microsoft notepad

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Dynamic Analysis, PLAXIS

Calibration model with static behaviour Average damping parameter selected based on hyperbolic curve

Statnamic Test Numerical Simulation PLAXIS

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Load [MN]

0 5 10 15 20 25 0 Extrapolation according to 20 Middendorp and Bakker

40

60 Correction for “rate effects”: 80 Undrained behaviour

Fy [kN/rad] 100 -5000 Undrained analysis 120 -4000 Displacement [mm] . Displacement[mm] -3000 “Rate effect ” 140

Fstn(t) -2000 160 Drained analysis Fu(t) -1000 180 Hyperbolic F=u/(p+q.u) 0 Hyperbolic F=Fref(u/uref)^0.5 0 0,05 0,10 0,15 0,20 200 |U| [m]

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Bochum, Pfahl 57 STN Cyclic Load Displacement Diagram 0 Cycle 1 Cycle 2 Cycle 3

5 Bochum, Pfahl 57 STN Static Cyclic Load Displacement Diagram Cycle 1 Cycle 2 Cycle 3 Hyp. Appr. Static Quick 10 0 Hyp. Appr. Static Long Term

15 5

Displacement [mm] 20 10

25 15

30 Displacement [mm] [mm] Displacement 20 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Load [MN]

25

30 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Load [MN]

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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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Statnamic provides alternative in case

 Static load tests are not feasible

 Re-use of existing Piles

 Determine Load-Settlement behaviour

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