Practice of Large Penetration Test after 1999 Ji-Ji Earthquake

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Practice of Large Penetration Test after 1999
Ji-Ji Earthquake

• Jiin-Song Tsai and Yean-Jhe Liou
• Department of Civil Engineering National Cheng
  Kung University
• 11. 4. 2003

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Aspects

• Field Conditions
• Facilities Instrumentation
• Experiment Results
• Summaries Lessons

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Liquefaction of Gravelly Ground

• BPT (Harder and Seed, 1986)
• Effects of hammers and casings
• BPT-SPT correlation
• FBPT (Sy and Lum, 1997)
• Effects of casing friction (Mud-injection Becker)
• LPT (Daniel, Howie and Sy, 2003)
• Scale effect of LPTs (scale-up SPT)
• TLPT (Tsai, Huang and Liou, 2003)
• Measurement of Energy Transfer

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TLPT Project
Dr. D.H. Lee NSC Coordinator
Dr. A.B. Huang Joint Project Coordinator
TLPT Research Team
Dr. A.B. Huang (Planning and Coordination)
Dr. P.S. Lin (Soil Investigation and Job Site
Preparation)
Dr. J.S. Tsai and Diagnostic Eng. Consultant LTD.
(Energy Measurement)
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Test Site Ground Condition
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Location
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Liquefaction of Test Site
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Layout
Da Li River
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Test Pit
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Profile ( B-14 )
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Facilities Instrumentation
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Casings of TLPT
Comparisons with BPT and FBPT
BPT FBPT
TLPT (Close end)
Mud-Injection (Close end)
Conventional (Open end)
405mm
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Steel Shoes
P1, P2
P3, P4 , P5
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BPT and TLPT Hammers
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Three-Segment Casings
P1, P2
P3, P4 , P5
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Instrumentation - Setup
Strain transducerAccelerometer
TNOsignal conditioner
Notebookcomputer
Set-A
Loadcell
InstruNet M100signal conditioner
Notebookcomputer
Set-B
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Instrumentation Set-A
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Loadcell Set-B Development
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Loadcells
P3, P4 , P5
P1, P2
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Q 1 How to place the sensors properly inside the
tube under limit working space ?

• A 1 Prefabricate the sensors module on a plastic
  sheet for one-time easy pasting

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Q 2 How to effectively cover sensors under limit
working space to resist high water pressure ?

• A 2 Fill up the tube with silica gel

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Q 3 How to isolate the sensors and wire cords
from high temperature induced by welding ?

• A 3 Wrap them carefully using asbestos belts

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Loadcell Calibration
500t MTS
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Shop Prefabrication
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Experiment Procedure
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Installation Steps

• Double-check Set-B, and label 30cm markson the
  tube.
• Erect the lower segment and slightly pound to
  the ground.

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Pounding Steps

• Bolt Set-A sensors onto casing. Connect Set-A and
  Set-B to signal conditioners.
• Record blow counts of 30cm penetration.
• Stop pounding before Set-A sensors were dragged
  into the ground. Dismount Set-A.

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Steps for next cycle

• Stretch Set-B cords to new outlet hole.
• Welding.
• Repeat the pounding
• steps until the uppersegment done.

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Correlate BPT-Nb and SPT-N60

• Sy and Lum method (1997)
• No shaft friction Rs

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Results
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Discussions
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Unsolved puzzle 1Why size effects on ENTHRU
results are not clearly shown ?
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Unsolved puzzle 2Why NL30 numbers of same
size casing are scattering?
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Failure

• No meaningful data of Set B !!
• Why?

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SimWave simulation Study

• Force-time history of Set-B

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• Interpretation
• High particle velocity fail the bounding
  between casing tube and strain gauges.
• Measures
• Adopt longer strain gauges (lower accuracy)
  to provide larger glue area.

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Summaries

• The first trial of local LPT (TLPT) is described
  and data are presented.
• Results of TLPT give an explanation to
  liquefaction of gravelly ground in the Ji-Ji
  Earthquake.
• Lessons learned give clues for future
  improvements.

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Appreciate all involvedTo be Continued ..