SEISMIC PERFORMANCE OF URBAN, RECLAIMED AND PORT AREAS -FULL SCALE EXPERIMENT USING BLAST TECHNIQUE

by

Takahiro SUGANO1) and Eiji KOHAMA2)

ABSTRACT A full scale lateral spreading experiment was carried out on November 13th, 2001 at Tokachi port in Hokkaido island, Japan. The primary objective of the experiment was to assess the performance of steel sheet pile quay walls subjected to liquefaction/lateral spreading. Two 5.5 m deep quay walls were designed and constructed, to investigate the damage mechanism of steel sheet pile quay walls. They were constructed with seismic design coefficients of k=0.15 and k=0 separately. The test site was reclaimed with dredged fine sand about 18 months before the test. The depth of the reclaimed sand layer was about 8 m and the test field area was around 4800 m2 (50 m by 96 m). Controlled blast technique was used to induce liquefaction/lateral spreading, and 127 blast holes each consisting 4 kg explosive material for lower part and 3 kg for upper part were charged. The total weight of explosive material was 840 kg. Various structures such as group pipe piles, gas pipes and buried structures were installed with measuring instruments. Two liquefaction remediation methods and several new measurement techniques were adopted. Forteen organizations were participated in this project. KEYWORDS: Full scale field experiment, Liquefaction, Lateral spreading, Reclaimed land

1. INTRODUCTION The 1995 Hyogoken-Nambu earthquake caused severe soil liquefaction in extensive areas of reclaimed land in Kobe. The soil liquefaction induced large ground displacements in the horizontal direction, which resulted in damage to buried structure such as lifeline pipes and foundations. Also, many caisson type quay walls were damaged in Kobe Port during the earthquake. Generally, three sets of data can be used to investigate the mechanism of damages; 1) Strong motion record nearby the damaged

facility, 2) Geotechecnical data, design conditions and

damage data ( i.e. deformation). and, 3) Numerical simulation or model test results However, an important piece of information as ‘behavior of structures during earthquake’ is not available. In this project, we focused on the behavior of full scale structures during liquefaction state and 14 organizations were jointed in the project as shown in Table 1. 1) Head, Structural Dynamics Division, Geotechnical and Structural Engineering Department, Port and Airport Research Institute, 3-1-1 Nagase, Yokosuka, Kanagawa 239-0826, JAPAN 2) Research Engineer, ditto

2. OUTLINES OF THE EXPERIMENT The test site was located in Pier No.4 at Tokachi Port in Hokkaido. The Pier No.4 filling construction was completed in June 2000 with use of dredged fine sands. The experimental yard area was around 4800 m2 (50 m by 96 m) and it was separated into two parts. In one part, steel sheet pile quay wall which was designed with seismic coefficient of k=0.15 was installed the other part the one designed with k=0 was employed. In this paper, the k=0.15 part is refered as region (A), and k=0 part as region (B). In region (B), 4% slope (25 m width, 50 m long) were constructed to induce lateral spreading. The typical soil profile is shown in Fig.1. The particle size distribution of the soils are shown in Fig.2, as can be sheen most of the soil samples are in ‘possibility of liquefaction’ zone. 2.1 Blast sequence

The blast hole is indicated in Fig.3 from A1 to A54 , from B1 to B48 and from C1 to C25. The first ignitions were A1 and B1 at the same time. Then, ignite next holes in order with 500 ms time interval which showed snake walking in plan view. Each hole consisting 4 kg explosive material for lower part and 3 kg for upper part were charged with 200 ms time interval, the ignite order was from lower part to top part.

2.2 Lift up mechanism (Fig.3) In region (A), The Japanese Geotechinical Society installed eight buried structures such as sewage water pipes to investigate the lift up mechanism during liquefaction and the countermeasures. The dimensions of the installed cylindrical structures were 1 m in diameter and 3.8 m in length. 2.3 Performance of Cement deep mixing soil improvement/Permeable grouting improvement

during liquefaction UC Berkeley and Japan Cement Deep Mixing Association installed four cement deep mixed specimens in region (A) as a 3.4 m by 3.4 m foot print cement deep mixing improvement to depth of 8 m (full improvement of reclaimed layer), 5.5 m , 3.5 m and no treatment. Permeable Grouting Method Association and Port and Airport Research Institute tried to injected 8 hrs gel time chemical grout in between sheet pile quay wall and the anchor pile to investigate the efficiency of permeable grouting method as shown left bottom zone of region (A) in Fig.3. 2.4 Performance of steel sheet pile quay walls Port and Airport Research Institute, Japan Dredging and Reclamation Engineering Association and Japan Steel Pipe Pile Association constructed two steel sheet pile quay walls with different design seismic coefficients including strain gauges and load cells. In region (A), the quay wall with seismic coefficient of k=0.15 ,and in region (B), the quay wall with k=0 were constructed. At the tie rod connectors just behind the sheet piles in region (B), special explosives were used so as to cut the tie rod to induce lateral spreading during liquefaction. 2.5 Performance of lifelines subjected to lateral spreading UC San Diego and Waseda University carried out the pile experiment. The three sets of pile foundations were installed behind the k=0 quay walls to determine the effect of pile groups on the pile response. 300 mm diameter steel pipe piles in pile groups having 900 mm spacing and a concrete pile cap (three single piles, 4-pile group, and 9-pile group) were constructed.

Two pipes were installed to intersect the lateral spreading direction at 90 degree angle, and one pipe was installed in the lateral spreading direction as shown in the right bottom part of Fig.3. Ten wireless transmition dynamic GPS devices (10 Hz time interval) were installed and attached to the structures to measure the deformation of structures during lateral spreading. 2.6 Investigation on the mechanism of lateral spreading Waseda university installed 11 GPS devices on the surface of slope with 1 Hz measurement interval, and installed vertical optical fiber modules to measure the deformation inside the slope. 2.7 Evaluation of impervious sheet properties when large deformations occur during and after earthquake National Institute for Land and Infrastructure Management Yokosuka, installed the impervious sheet used for garbage dumping ground. Many of Japanese garbage dumping grounds are located in coastal area. To keep the garbage material and polluting matter inside the designated area, the performance of impervious sheet is important. 2.8 Survey and Sounding techniques Port and Airport Research Institute conducted several sounding tests as follows: SPT-blow count, seismic cone penetration test, portable cone penetration test, automatic Swedish weight sounding, and dilatometer test. These tests were conducted about a couple of months before, the day before and after the blast. It is also planed to perform them in June 2002. National Institute of Advanced Industrial Science and Technology research team used the resistivity method to measure the density profile of the liquefied soil.

Earthquake Research Institute, Tokyo Univ. and Port and Airport Research Institute compared the data obtained from the dynamic GPS installed in region (A) and conventional laser survey data. Chuo Univ. used the radio controlled helicopter to take photos of the experimental site before and after the blast and automatic computer processing technique to measure the deformation. Chuo Univ. also installed CCD camera into the vertical transparent cylinder to visualize the soil profile during the test. Waseda Univ. team tried to detect the liquefied soil layer profile during liquefaction by using acoustic tomography with pseudo random binary sequence code technique. UC Berkely and Port and Airport Research Institute installed both conventional strain gauge type accelerometers and wireless accelerometers which using the micro electro mechanical systems and bluetooth transmission. In this project around 800 sensors were installed and total length of signal cable between sensor and amplifier was about 40 km. The data obtained from wireless accelerometers showed good agreement with the data obtained from conventional accelerometers. 2.9 Re-liquefaction phenomena Civil Engineering Research Institute of Hokkaido is interested in the re-liquefaction phenomena and curried out the post experiment on Dec. 14th , 2002 with UC San Diego and Port and Airport Research Institute. In region (B), the controlled blast were applied with the group pile foundations as its center.

3. SUMMARY OF RESULTS The overall deformation of the test field is shown in Fig.4. The maximum horizontal displacement of quay wall in region (A) was

about 30 cm, region (B) was about 130 cm respectively. Due to the horizontal movement of quay walls, lateral spreading was occurred in region (B). However, three sets of group piles played a role in control works against lateral spreading as shown in Fig.5. In this experiment, acceleration caused by controlled blasting could not simulate actual earthquake acceleration as shown in Fig.5. Fig.5 shows an acceleration time history recorded at region (A) quay wall, the maximum acceleration was over 10 g. On the other hand, excess pore water pressure was built up overburden pressure as shown in Fig.6. The bending moment distribution of initial

condition, maximum displacement condition and residual condition are shown in Fig.7. The failure of sheet pile quay walls occurred due to the reduction of resistance of anchor pile during liquefaction, then sand water mixture fluid push the quay walls. Many kinds of challenges to investigate seismic performance of urban, reclaimed and port were conducted in collaboration with 14 organizations. The reports in this paper include wide filed subjects related to liquefaction/lateral spreading phenomena. The analysis works is presently continuing by individual organization participated in this experiment. The results will be presented in the future.

Table 1 Organizations of the research project

Organization Research content Role

Port and Airport Research Institute (PARI)

1. Investigation on the dynamic characteristics of ground before and after liquefaction 2. Investigation on seismic behavior of sheet piles, anchor piles and tie rods/wires

supervision of entire experiment, measurement of behavior of sheet piles and analysis

National Institute for Land and Infrastructure Management

(NILIM)

1. Evaluation of impervious sheet properties when large deformations occur during and after earthquake 2. Investigation on characteristic of microtremor before and after earthquake

analysis of experimental results

Japan Dredging and Reclamation Engineering Association (JDREA)

Investigation on seismic behavior of sheet piles, anchor piles, tie rods and surrounding ground

execution management and analysis

Japanese Association for Steel Pipe Piles (JASPP)

Investigation on seismic behavior of sheet piles, anchor piles, tie rods and surrounding ground

measurement of sheet piles displacement and analysis

University of California, San Diego (UCSD)

Investigation on behavior of pile groups and buried pipes Measurement and analysis about interaction between structure and ground during lateral flow

Cement Deep Mixing Association

(CDM Association)

Investigation on properties of ground improved by cement deep mixing method

cement mix design, execution management and analysis

University of California, Berkrey (UCB)

Investigation on properties of ground improved by cement deep mixing method

measurement of improved ground behavior and analysis

The Japanese Geotechnical Society (JGS)

Investigation on behavior of buried pipes imposed to up-lift pressure of liquefaction

measurement of underground pipe behavior and analysis

Waseda University (Waseda Univ.)

1. Investigation on ground movement during and after lateral flow and behavior of buried single pile 2. Investigation on elastic wave velocity in liquefied ground 3. Measurement of vibration at adjacent buildings 4. Measurement of underground displacements

acoustic tomography, measurement of underground displacement by using optical fiber, GPS, etc.

Permeable Grouting Method Association

(PGM Association) Confirmation of efficiency of permeable grouting method execution management and analysis

Tokyo University, Earthquake Research Institute

(Tokyo Univ.) Measurement of 3D dynamic displacements by GPS measurement by dynamic GPS

Chuo University (Chuo Univ.)

1. Investigation on water film phenomenon occurred by liquefaction 2. Measurement of ground displacements

measurement by borehole-camera and radio-control helicopter

National Institute of Advanced Industrial Science and

Technology (NIAIST) Investigation on underground density profile of liquefied soil measurement by resistivity method

Civil Engineering Research Institute of Hokkaido (CERI)

Investigation on behavior of re-liquefied ground analysis of experimental results

Fig.1 Typical soil profile

Fig.2 Particle size distribution

10-3 10-2 10-1 100 101 1020

25

50

75

100

Perc

enta

ge F

iner

by

Wei

ght (

%)

Grain Size (mm)

+3.00m +2.00～+1.70m +1.00～+0.60m +0.00～-0.46m -1.00～-1.45m -2.00～-2.45m -3.00～-3.45m -4.00～-4.45m -5.00～-5.30m -6.00～-6.30m -7.00～-7.30m -8.00～-8.30m

A-5

B-1 +3.00m +2.00～+1.70m +1.00～+0.70m +0.00～-0.35m -1.00～-1.40m -2.00～-2.45m -3.00～-3.45m -4.00～-4.30m

Possibility of liquefaction

High possibilityof liquefaction

20.00

B7

L=10,500

A30

A29

A28

A27

A26

A31

A32

A33

A34

A35

A40

A39

A38

A37

A36

A41

A42

A43

A44

A45

C5

C25

+3.0

１：

３

１：２

１：２

１：３

１：

３

+3.0

+3.0

-1.0

A

+3.0

+3.0

12.50

+3.0

+3.0

-5.0

-5.0

１：

３

24.00 50.00

21.00

16.00

24.00

１：

３

１：３

-1.0

12.00

2.25

2.25

3.40

L=11.5m

L=11.5m

L=25.6m

L=22.0m

34.507.50 25.00

6.00

B1

E2

E1E4E3

F1

6.00

① ②

6.00

L=25.6m

3.00

4.00 5.20

3.80

3@6=18.00

3.80

3.30

3@6=18.00

3.30

6.006.00

A1

A2

A3

A4

A5

B1

B2

B3

B4

A10

A9

A8

A7

A6

B8

B7

B6

B5

A11

A12

A13

A14

A15

B9

B10

B11

B12B13

B14

B15

B16

A16

A17

A18

A19

A20

B20

B19

B18

B17

A25

A24

A23

A22

A21

B24

B23

B22

B21

B25

B26

B27

B28

B32

B31

B30

B29

B33

B34

B35

B36

A49 A48

A47

A46

B40

B39

B38

B37

A50

A51

B41

B42

B43

B44

B46

A53

A52

B48

B47

6@6=36.00

C10

C11

C20

E5 E6

F2

A1 A2

B2

B3 B4 B5 B6

C1 C3C2 C4

D1 D4

A54

D1

D2

D3

B45

B

B

CC

DD

EE

A5

A4

B4

B3

B1

：UCSD - pore water pressure in one-elevation

3.00

C9C8C7C6C5C4C3C2C1

9@6=54.00

C12

C13

C14

4@6=24.00

C19

C18

C17

C16

C15

4@6=24.00

C21C22C23C24

63.20

12.50

14.20

24.60

D3D2

S7

S11

S6

S2 S1

S5

S8 S9

S4

S10

S12

S3

3.40

AD3

AD5

AD8

PP4AD9

AD7 PP3

AD2

PP1

PP5

6

4

2

6

42

6

4

2 2.24.2

6.2

2

6

4

AD1

AD4

PP2

AD5 PP6

L=11.5m

6

42

: Waseda Univ. (acoustic tomography） : Chuo Univ. （borehole camera）

　

25.60

12.00

49.80

5.00

24.60

25.20

: Waseda Univ. (single pile） : Waseda Univ. (underground disp.） : Waseda Univ. (investigation on blasting)

(qua

y w

all w

ith la

tera

l flo

w)

(ase

ism

ic q

uay

wal

l)

(des

ign

for

eart

hqua

kes)

(des

ign

for

ordi

nary

con

ditio

n)

JGS(area embedded piles

and manholes)

NILIM (impervious sheets)

Waseda Univ.(underground displacement)

UCSD pipe φ500

UCSD pipe φ508

UCSD pipe φ268

UCSD pile φ318

UCSD pile φ318

Legend (organizations)

PARI

JASPPJDREA(sheet pile and anchor pile)

design water level

design water level

UCSD pile φ318

Chuo Univ.

Waseda Univ. pile φ318

Chuo Univ.

Chuo Univ.

Legend (holes for measurement)

Legend (holes for charging blast)

Waseda Univ. (investigation on blasting)

Waseda Univ. (investigation on blasting)

Waseda Univ. (investigation on blasting)

(Research on properties of ground)

PARI

JASPPJDREA(sheet pile and anchor pile)

PARI

UCB & CDM Association

Was

eda

Uni

v. (

acou

stic

tom

ogra

phy)

1. Investigation on dynamic properties of sheet pile quay walls

2. Research on countermeasures against liquefaction

3. Research on properties of liquefied ground

5. Investigation on properties of ground by acoustic tomography

PGM Association(efficiency of permeable grouting method)

NIAIST

: UCSD

: PARI JASSP JDREA : NILIM

: UCB & CDM Association

: JGS : NIAIST

: PIGMA6. Research on dynamic properties of ground improved by CDM

length of embankment

：UCSD - pore water pressure in three-elevation

：UCB&CDM pore water pressure transducer：UCB&CDM accelerometer

plate cut 20sheets

：UCSD - inclinometer

：PARI - accelerometer + pore water pressure transducer

：PARI - pore water pressure transducer：boring and sampling point

：to cause liquefaction

4. Research for visualizing liquefaction phenomenon

11. In-situ experiment on aseismic performance of impervious sheet

9. Observation of lateral flow by GPS10. Measurement of vertical displacement after lateral flow

12. Evaluation of ground behavior by precise camera when lateral flow occurs

：to shake the liquefied ground (outside the area which measuring transducers are installed)

3800010500

2000 33000 3000

12000 8000

800045

00

４

３

+3.0m

-5.0m

+3.0m

area without lateral flow, B-B cross section,　vertical:horizontal = 2:1

+2.0m

9.7510.00 PARI(Research on propertiesof ground)

JGS(area embedded pipe and manhole)

３

４

C20

３

４

C21

３

４

C22

３

４

C23

３

４

C24 C19

12.25 7.50slope

３

４

C25

-1.5m

-5.0m

3760010500

2000 33000 2600

3859

4104

4349

4547

4839

5084

5329

11000

8000

800045

00

３ ３ ２ ２

３ ３ ３ ３ ４ ４ ４４

４ ２ ２４ ４ ４ ４４ ５ ５ ５ ５ 4

3

４

+3.0m

-5.0m

3615

UCSD　　　　　　

　piles・pipeline

impervious sheets

+2.0m

+3.0m+4.0m

+5.0m

-0.5m

-4.5m

3500

area with lateral flow, D-D cross section,　vertical scale:horizontal scale = 2:1

cutting point

4000

C13

pipe

（B38,B39)（B33-B35)

7. Experiment on buried structures imposed by lift-up pressure when liquefaction occurs

(unit : m)

(unit : mm)

(unit : mm)

8. Investigation on behavior of pile foundations, buried pipes and so on when lateral flow occurs

Fig. 3 Plan view of the test site

-700-600

-500

-500

-500 -40

0

-400

-400

-300

-300

-200

-200

-200

-200

-100

-100

-100

-100

-100

-100

-100

0

0

0

0

00

0

0

0

100

200

-850-800-750-700-650-600-550-500-450-400-350-300-250-200-150-100-50050100150200

Contour of Settlement (mm)

The Result of Survey (after 1 day)

１：３

１：２

１：２

１：３

１：３

１：３

１：３

１：３

A4

A3

A2

A1

B1T

B2T

B3T

B4T

B5T

B6T

C1

C2

C3

C4

D1T

D2

D3T

D4

D5

D6

D7

D8

D9

E1 F1

25

24

23

22

21

33

2

332 20

31

6

730

29

10

1128

19

18

2713

14

26 17

15

16

12

9

8

5

4

1

H5

H4

H3

H2

H1T

I1 I4

I3

I2

I5

S1

S2

S3

S4

S5

S6

S7

S8

S9

T6

T5

T4

T3

T2

T1

CT-1

CT-2

Survey Point (SATOKOGYO)

Vector of Displacement (m)

Survey Point (TOBISHIMA)

Survey Point (Geotechical Society)

Geo.scale 0 10 20

Displacement 0 2 4

Survey point

Vector of Displacement (m)

Fig.4 Deformation of test fields

ground surface before test

ground surface after test

face line before test

surveying target

1.0m

※deformation（×10）

Fig.5 Lateral spreading deformation

-500 -1000 500 1000

strain(μ)

-500 -1000 500 1000

strain(μ)

イベント時刻(sec)

タイロッド張力

(kN/m)

実験前 0.000 52.2

タイロッド張力最大 45.725 184.4

鋼矢板正負ひずみ最大 45.760 150.2

控え直杭正ひずみ最大 46.575 99.4

実験後 90.000 90.2

Sheet pile Anchor pile

before test

after test

max strain in sheet pile

max strain in anchor pile

Time Tension in tie rod

-2

-1

0

1

2

Acc

. (G

) AB7x

-2

-1

0

1

2

Acc

. (G

) AB2x

200

150

100

50

0

-50

Exc

ess

Pore

Wat

erPr

ess.

(kP

a) PB11

Fig.6 Acc. caused by blast

Fig.7 Excess pore water pressure

Fig.8 Strain distribution of sheet and anchor pile

0 60

0 60

Photograph Test site : before experiment

Photograph Tokachi port from window of airplane Photograph Under construction

Photograph Installing blast Photograph During blast

Photograph Visitors during blast

Photograph Boiling sand caused by liquefaction Photograph After sand boil

Photograph Sheet pile quay wall after blast (PARI, JDREA & JASPP)

Photograph Pile groups (UCSD)

Photograph Pile groups (UCSD) Photograph Single Pile (Waseda Univ.)

Photograph Impervious sheet (NILIM) Photograph Lift-up of buried pipe (JGS)

Photograph Improved ground by CDM (UCB & CDM Association) Photograph Execution of PGM (PGM Association)

Photograph Radio control helicopter (Chuo Univ.) Photograph Test site from helicopter’s camera (Chuo Univ.)

Photograph Borehole camera (Chuo Univ.) Photograph Re-liquefaction test during heavy storm on Dec 14th, 2002