Post on 04-Apr-2018
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Statnamic Pile Load Testing
Flip Hoefsloot, Fugro The NetherlandsJanuary 2010
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Contents Menu
Load Testing Methods
Description Statnamic
Video of TestApplication
Interpretation
GuidelinesConclusion
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Load Testing Methods
STATIC
100 %
Load
Displacement
DYNAMIC
1-2 %
STATNAMIC
5-10%
High pressure gas
High pressure gas
Strain
Acceleration
Load
Displacement
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Description Stanamic
1 2
3 4
A = Pile B = Load cellC = Cylinder D = Piston with chamberE = PlatformF = SilencerG = Reaction massH = Gravel ContainerI = GravelJ = LaserK = Laser beamL = Laser sensor
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Fugro Profound
Knowledge and experienceStatnamic(Peter Middendorp)
ClientsWord wide
Description Stanamic
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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
Description Stanamic
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Equipment:
80 tons reaction mass
7 trailers for transport2 to 3 days a test
one cycle of testing
Description Stanamic
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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 analyzingTechniques
•Applicable only for Steel PipePiles
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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: Tf Duration of rapid loadL pile lengthcp stress wave velocity test pile
1000/
10 ≤≤p
f
cL
T
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Interpretation
Fstn = statnamic force, measuredFst = static resistanceu = displacement, measuredv = du/dta = d2u/dt2
m = pile massC = damping coefficient
)()()()( tvCtamtFtF ststn ⋅+⋅+=
M
Fstn
u F stn
k C
m
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Interpretation
Load Cell
Laser Sensor
Accelerometer
0
5
10
15
200 50 100 150 200 250 300
Time [ms]Lo
ad [M
N]
0
10
20
30
40
50
60
0 50 100 150 200 250 300
Time [ms]
Dis
plac
emen
t [m
m]
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Interpretation
Estimated damping parameter C (hyperbolic curve)
0
10
20
30
40
50
60
0 5 10 15 20
Load [MN]D
ispl
acem
ent [
mm
] .
Fstn(t)
Fstatic(t)
UP
)()()()( tvCtamtFtF stnst ⋅−⋅−=
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Interpretation
Simplified input ofdynamics boundary conditions withMicrosoft notepad
Dynamic Analysis, PLAXIS
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Interpretation
Dynamic Analysis, PLAXIS
Calibration model with static behaviourAverage damping parameter selected based on hyperbolic curve
Statnamic Test Numerical Simulation PLAXIS
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Interpretation
Extrapolation according toMiddendorp and Bakker
Correction for “rate effects”:
Undrained behaviour
0
20
40
60
80
100
120
140
160
180
200
0 5 10 15 20 25
Load [MN]
Dis
plac
emen
t [m
m]
.
Fstn(t)
Fu(t)
Hyperbolic F=u/(p+q.u)
Hyperbolic F=Fref(u/uref)^0.5 0 0,05 0,10 0,15 0,20
-5000
-4000
-3000
-2000
-1000
0
|U| [m]
Fy [kN/rad]
Drained analysis
Undrained analysis
“Rate effect”
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30
25
20
15
10
5
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Bochum, Pfahl 57STN Cyclic Load Displacement Diagram
Dis
plac
emen
t [m
m]
Load [MN]
Cycle 1 Cycle 2 Cycle 3
30
25
20
15
10
5
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Bochum, Pfahl 57STN Static Cyclic Load Displacement Diagram
Dis
plac
emen
t [m
m]
Load [MN]
Cycle 1 Cycle 2 Cycle 3 Hyp. Appr. Static QuickHyp. Appr. Static Long Term
Interpretation
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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