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

SSIRL

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

SSIRL Soil-Structure Interaction Research Laboratory

Aspects

• Field Conditions

• Facilities & Instrumentation

• Experiment & Results

• Summaries & Lessons


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 Bec

ker)

• LPT (Daniel, Howie and Sy, 2003)– Scale effect of LPT’s (scale-up SPT)

• TLPT (Tsai, Huang and Liou, 2003)– Measurement of Energy Transfer


TLPT Project

TLPT Research Team

Dr. A.B. Huang

(Planning and Coordination)

Dr. J.S. Tsai and Diagnostic Eng. Consultant LTD.

(Energy Measurement)

Dr. P.S. Lin(Soil Investigation

and Job Site Preparation)

Dr. A.B. Huang Joint Project Coordinator

Dr. D.H. LeeNSC Coordinator

SSIRL

Test Site & Ground Condition


Location

TaichungCounty

TaichungCity

Nantou

Ming jianJiJi

NantouCounty

FengyuanDungshr

Drolan

MiaoliCounty

ChangHuaCounty

Yuanlin

YunlinCounty Chelunpu

Fault

Epicenter

Jushan

WufeugTest Field


Liquefaction of Test Site

Fu Tin Bridge

Liquefaction Outlet

South Levee ofDa Li River


Layout

Da Li River


Test Pit

G . W . L . ： - 4 . 5 m P r o p e r t i e s ( % )

D e p t h

( m ) D e s c r i p t i o n

G r a v e l S a n d S i l t C l a y U S C S t

( g / c m 3 ) nw

( % ) sG

S F B a c k f i l l

0 . 5

1 . 5 5 3 4 4 3 0 G P 1 . 9 9 7 . 2 4 2 . 6 7

2 . 5

3 . 5

G r a v e l w i t h M e d i u m t o c o a r s e l o o s e s a n d

cmd 15max

w i t h s i l t y c l a y

4 . 5

5 . 5

6 . 5

G P


Profile ( B-14 )

2

4

6

8

10

12

14

16

18

20

22

24

26

28

S-1

S-0

S-0

S-0

S-0

S-0

S-0

S-0

S-0

S-0

S-0

S-0

5 5 5

9 9 11

13 22 35

50/12 cm

100/17 cm25

50/4 cm

50/14 cm

50/8 cm

50/13 cm

50/5 cm

50/6 cm

50/14 cm

Ground EL: +35.16 m Date: 1/21/2000 - 1/23/2000

Location : N2664115 : E215570 Hole No. : B-14 G.W.L. :-3.5 m (01/22/00)

Depth(m)

SempleNo.

S.P.T

15 cm 15 cm 15 cmDescirption

Gravel with medium to coarse sand

-2.1~7.0 m :

Occasional thin layersof fine to medium sand

dmax 16 cm~~

SSIRL

Facilities & Instrumentation


Casings of TLPT

170mmMudinject

140mm

170mm

305mm

170mm

220mm

405mm

BPT & FBPT TLPT(Close end)Conventional

(Open end)

Mud-Injection

(Close end)

168mm 232mm

208mm 272mm

Comparisons with BPT and FBPT


Steel Shoes

P1, P2 P3, P4 , P5


BPT and TLPT Hammers


Three-Segment Casings

Segment 3 Segment 2 Segment 1

:point welding:ψ 40mm hole for Set-B signal cords unit: mm

500 500 500 6006500 6500 5000

18000

208

20

20

50

150

30

30

168

100

272

20

2040

232

Toe

40

ψ 168mm casing

ψ 232mm casing

Shoe

P1, P2

P3, P4 , P5


Instrumentation - Setup

Strain transducerAccelerometer

TNOsignal conditioner

Notebookcomputer

LoadcellInstruNet M100

signal conditionerNotebookcomputer

Set-A

Set-B


Instrumentation – Set-A

accelerometer

ψ232mm casing

strain transducer

bolt

accelerometer

SSIRL

Loadcell & Set-B Development


Loadcells

P1, P2 P3, P4 , P5


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

cm1


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


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

A 3: Wrap them carefully using asbestos belts


Loadcell Calibration

500t MTS


Shop Prefabrication

SSIRL

Experiment Procedure


Installation Steps

• Double-check Set-B, and label 30cm markson the tube.

• Erect the lower segment and slightly pound to the ground.


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.


Steps for next cycle

• Stretch Set-B cords to new outlet hole.

• Welding.

• Repeat the pounding

steps until the uppersegment done.


Correlate BPT-Nb and SPT-N60

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

Rs = 0 kN 45 90 135 150 225

270

315

360

80

60

40

20

00

100

20 40 60 80 100

BPT Nb30 ( blows / 30 cm )

SPT

N60

( b

low

s / 3

0 cm

)


Results

0 40 80 120Blow Count N L

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P1P2

0 40 80 120Blow Count N L

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P3P4P5

0 40 80 120 160Transfered N 60

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P1P2

0 40 80 120 160Transfered N 60

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P3P4P5

SSIRL

Discussions


Unsolved puzzle 1:Unsolved puzzle 1:

Why size effects on ENTHRU results are not clearly shown ?

0 20 40 60 80 100E N T H R U (% )

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P1P2

0 20 40 60 80 100E N T H R U (% )

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P3P4P5


Unsolved puzzle 2:Unsolved puzzle 2:

Why NL30 numbers of same size casing

are scattering?

0 20 40 60 80 100Energy-Corrected N L30

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P1P2

0 20 40 60 80 100Energy-Corrected N L30

1 8

1 7

1 6

1 5

1 4

1 3

1 2

1 1

1 0

9

8

7

6

5

4

3

2

1

0

De

pth

(m

)

P3P4P5


FailureFailure

No meaningful data of Set B !!

Why?


SimWave simulation Study

Force-time history of Set-B

0 0 .5 1 1 .5 2 2 .5 3Tim e (m s)

0

4 0 0 0

8 0 0 0

1 2 0 0 0

1 6 0 0 0

2 0 0 0 0

2 4 0 0 0

Fo

rce

(kN

)

FzV

ε=2.23×10-3

εallow=5×10-2

Particlevelocitydoubled

1500

mm

5000

mm

400m

m

Hammerradius=260mmweight=2.5t

ψ232mmSegment 1area=24127mm

Set-B


• 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.


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.

SSIRL

Appreciate all involved…

To be Continued …..

Documents

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