SEISMIC DAMAGE ASSESSMENT OF RESIDENTIAL
FILL GROUND IN THE EASTERN PARTOF KYOTO BASIN
CAI Xiaoguang∗
MEE08168

Supervisor: Toshitaka KAMAI ∗∗Fawu WANG ∗∗∗ABSTRACT
Several earthquakes record that the residential fills always suffer severe damages. In order to know theseismic damage mechanism and evaluate the damage extent of residential fill ground, research iscarried out on two fill grounds in the eastern part of Kyoto basin. The research works include fieldsurvey using surface wave explorations; mechanism analysis by using Fast Lagrangian Analysis ofContinua (FLAC) software. Some remarkable conclusions are summarized as follows: In Jyodo-ji area,
it is a residential fill on soft alluvium ground. The geological condition is back swamp. The thicknessof surface fill soil is about 1~4 meters. The simulations show that the shear strain accumulates in thesoft sediments. Sliding arc surface generates in the upper part of the ground. In Kiyomizu-dera area, it
is a valley filled ground. The geological condition is hilly platform. The simulations show that fill soil
parts have larger shear strain and displacement. With the groundwater level increasing, theacceleration amplification ratio slightly decreases, but the shear strain band and displacement zone
become larger.
Keywords: Fill ground, Damage assessment, Surface wave exploration, Groundwater level effect

1. INTRODUCTION
With the economic development, the urbanization trend becomes more and more popular in the world.
People move to cities and reclaim the ground for residential land. Some lands are coming from former
marshland, pond or hilly areas. People flatten the ground by cut or filled soil. The changed landforms
sometimes increase the damage potential, especially during earthquake. In recent year, there are about
10 earthquakes that caused residential fill ground damage (Kamai, 1995, 2005, 2008). So it aroused
the concern of researcher. Previous research show that the reason for the residential fill grounddamage includes intense seismic motion, terrain condition, groundwater level, site condition, etc(Yoshida, 2001;Okimura, 2006). But the seismic damage mechanism of fill ground is not well
explained. So in this study, the seismic damage mechanism will be researched by using surface wave
exploration and numerical analysis by Fast Lagrangian Analysis of Continua (FLAC) software.

2. SURFACE WAVE EXPLORATION ON RESIDENTIAL FILL GROUND
In this study, the ground conditions of two residential fill ground areas in the eastern part of Kyoto
basin are introduced. They are Jyodo-ji area and Kiyomizu-dera area (Figure 1).

∗

Lecturer, Institute of Disaster Prevention Science and Technology, Beijing, China
Professor, Disaster Prevention Research Institute of Kyoto University, Kyoto, Japan∗∗∗
Assistant Professor, Disaster Prevention Research Institute of Kyoto University, Kyoto, Japan
∗∗1

2.1 Site condition of Jyodo-ji area
Jyodo-ji area is a small basin between Yoshita mountain on the west side and Kurodani hill on thesouth side. The basin is about 1km from south to north and about 500~600m from east to west.
Shirokawa pass through this area from north to south. Most area is back swamp. It was farmland in
1922, and due to the urbanization, it becomes residential land now. During the 1995 Kobe earthquake,
Jyodo-ji area suffered severe damage(Uemura, 1999). The location of damaged house concentrated inBaba machi and Minamida machi. There were about 40 houses’ tiles fell down. Most of the damaged
house located on the back swamp area. The depth of fill soil is ranged 1 to 4 meters. Geology
columnar section shows there is a humus soil layer on the surface (KG-NET, 2008). The thickness ofthe soft mixture layer is more than 4 meters. The location of exploration sites and shear wave velocity
distribution in two sites of Baba machi are showed in Figure 3. There are some parts of soft sedimentin the ground. The average shear velocity is 130m/s.

A

N valuegravel mixed sandhumus soil
sandjade stony gravel
sand
gravel mixed sand
sand
clay
sand
sandy clay

B

Figure 1. Location of two residential fill groundin Kyoto city
A:Jyodo-ji area；B: Kiyomizu-dera area
(Uemura, Y. 1999)

Figure 2.Geology columnar section in Baba
machi
(KG-NET, 2008)

soft sedimentsoft sediment

A-1
A-2

A-1 Site

soft sedimentsoft sediment

A-2 Site
Figure 3. Exploration Location and shear wave velocity distributions in two sites of Baba machi
2.2 Site condition of Kiyomizu-dera area
Kiyomizu-dera area is hilly platform. There are some deep valleys from east to west. Some lowland ofvalley is residential filled ground. Despite little damage in 1995 Kobe earthquake, some damaged
house can be seen in new developed area (near B-3 site). From the exploration results, fill ground canbe seen clearly in B-2 and B-3 sites (Figure 4).

2

soft

B-1 Site
B-3

fill

B-2

B-2 Site
B-1
fill

B-3 Site
Figure 4. Exploration Location and shear wave velocity distributions in in Kiyomizu-dera area

3. SEISMIC RESPONSE ANALYSIS ON RESIDENTIAL FILL GROUND
Seismic response of the fill ground in Jyodo-ji area and Kiyomizu-dera area are analyzed by FLAC
software. The potential damage mode of the ground will be discussed.
3.1 Analysis results of fill ground in Jyodo-ji area
According to the surface wave exploration results (Figure 3) and geology columnar sections results,
FLAC model of A-1 site is set up as Figure 6. Water level is 3 meters below the ground level. Soilmodel 1-5 uses the Finn model and soil model 6 uses the Mohr-Coulomb model (Figure 6). Horizontal
boundary uses free field boundary. The Hyogo-ken-Nanbu earthquake ground motion record obtainedat Higashiyama (in Kiyomizu-dera area) in Kyoto city is used as input acceleration time history(Figure 5 Nakamura, Y., 1996,).
EW

0.8

8-Aug-09 22:06
step
2779
Flow Time1.2141E+08-6.444E+00 <x< 1.224E+02-4.944E+01 <y< 7.944E+01

-0.4

0

2E 1

A
B
C
116m

-0.8

3.000

23m

0.0

5.000

30m

User-defined Groups
User:soil6
User:soil5
User:soil2
User:soil3
User:soil4
User:soil1
Grid plot2

Acc(m/s )

0.4

1.000

-1.000-3.000Figure 6. FLAC model of A-1 site2

-0.987m/s (10.95s)
-1.2
0

5

10

15

20

25

30

Time(s)Figure 5. Input acceleration time history
The ground amplified the seismic motion about 2.3 times (Figure 7). Both B and C elements have highpore pressures during earthquake (Figure 8).There is a shear strain band generated from the upper tothe middle of the ground (Figure 9). The upper part has slide potential (Figure 10, the part in dot line).

3

140

3

B
C

130
2

2.264m/s (10.99s)

120

Pore pressure (kPa)2

Acc(m/s )

2

1

0

110
100
90
80
70
60
50

-1
40
30

-2
0

5

10

15

20

25

0

30

5

10

20

25

30

Figure 8. Pore pressure development atelement B and C

Figure 7. Acceleration response at the groundsurfaceDynamic Time 3.0000E+01-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

Dynamic Time 3.0000E+01-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

Max. shear strain increment
0.00E+00
1.00E-02
2.00E-02
3.00E-02
4.00E-02
5.00E-02
6.00E-02
7.00E-02
8.00E-02

X-displacement contours-1.50E-01-1.25E-01-1.00E-01-7.50E-02-5.00E-02-2.50E-02
0.00E+00
2.50E-02
5.00E-02
7.50E-02

Conto r inter al

15Time (s)Time(s)

1 00E 02

Figure 9.Shear strain increment

Figure 10.Horizontal displacements

3.2 Analysis results of fill ground in Kiyomizu-dera area
3.2.1 B-2 Site
FLAC model of B-2 site is seen in Figure 11. The geological condition of the ground is valley filled
ground. Water level, horizontal boundary and the input motion are same as the input of A-1. The
ground amplified seismic motion 3.97 times (Figure 12). From the top to the middle part of the ground,
there is a shear strain band generated. The upper part has large horizontal displacements.
4
3
step
0
-4.778E+00 <x< 9.078E+01-3.278E+01 <y< 6.278E+01

2

A

fill

1
2

Acc (m/s )

B

2.500

30m

28m

User-defined Groups
User:soil6
User:soil5
User:soil4
User:soil1
User:soil3
User:soil2
Grid plot

3.500

1.500

0
-1

0.500

-2
0

2E 1

86m

-0.500-3
2-3.914m/s (11.13s)-4-1.500-5
0Figure 11. FLAC model of B-2 site

5

10

15

20

25

30

Time (s)Figure 12. Ground acceleration response
Flow Time 1.9015E+08
Dynamic Time 3.0000E+01-4.958E+00 <x< 9.064E+01-3.295E+01 <y< 6.265E+01

Flow Time 1.9015E+08
Dynamic Time 3.0000E+01-4.958E+00 <x< 9.064E+01-3.295E+01 <y< 6.265E+01

Max. shear strain increment
0.00E+00
1.00E-03
2.00E-03
3.00E-03
4.00E-03
5.00E-03

X-displacement contours-1.75E-01-1.70E-01-1.65E-01-1.60E-01-1.55E-01-1.50E-01-1.45E-01-1.40E-01-1.35E-01

Contour interval= 1.00E-03

Figure 13. Shear strain increment

Figure 14.Horizontal displacements

3.2.2 B-3 Site
FLAC model of B-3 site is seen in Figure 15. Water level, horizontal boundary and the input motion
are same as the input of A-1. The ground amplified seismic motion 3.87 times (Figure 16). In the
middle part of the ground, there is a shear strain band generated (Figure 17). The fill soil part has large
horizontal displacement (Figure 18). The results can well explain why there are a lot damaged housesin this area.

4

4
3
5.000

2

LEGEND
9-Aug-09 15:49
step939-4.333E+00 <x< 8.233E+01-2.833E+01 <y< 5.833E+01

01
2

Acc (m/s )User-defined Groups
User:soil10
User:soil9
User:soil3
User:soil4
User:soil5
User:soil6
User:soil7
User:soil2
User:soil1
User:soil8
Grid plot

4.000

A

3.000

fill
30m

2.000

26m

B

0
-1
-2

1.000

-3
0.000

78m

2

-3.822m/s (11.14s)-4-1.000

2E 1

0

5

10

15

20

25

30

Time (s)Figure 15. FLAC model of B-3 site

Figure 16. Ground acceleration response

step 371177
Flow Time
1.8778E+05
Dynamic Time 3.0000E+01-4.528E+00 <x< 8.218E+01-2.851E+01 <y< 5.820E+01

step 371177
Flow Time
1.8778E+05
Dynamic Time 3.0000E+01-4.528E+00 <x< 8.218E+01-2.851E+01 <y< 5.820E+01

Max. shear strain increment
0.00E+00
2.50E-03
5.00E-03
7.50E-03
1.00E-02
1.25E-02

X-displacement contours-2.00E-01-1.90E-01-1.80E-01-1.70E-01-1.60E-01-1.50E-01
Contour interval= 5.00E-03

Contour interval= 2.50E-03

Figure 17. Shear strain increment

Figure 18.Horizontal displacements

4. GROUNDWATER LEVEL EFFECT ON SEISMIC STABILITY OF FILL GROUND

Acc. of surface / Acc. of basement

2.6

2.5

2.4

2.3

2.2

-1

-2

-3

-4

-5

-6

Groundwater level (m)Figure 19. The relation between groundwaterlevel and acceleration amplification ratio

A-1 site is used as calculation model. All the
calculation parameters are same as before except
groundwater level. The groundwater level is changed
into 1, 3 and 6 meters below ground surface. Results
are seen in Figure 19~21. With the groundwater level
increasing, the acceleration amplification ratio
slightly decreases, but the shear strain band anddisplacement zone become larger. When the groundwater level is high, more area will have high porepressure. When liquefaction occurred, on the one
hand, liquefaction ground behaving as an isolationcushion can slightly reduce the seismic motion; on theother hand, liquefaction lowers the effective stressand it can induce large horizontal displacement.

y-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

y-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

Max. shear strain increment
0.00E+00
2.00E-02
4.00E-02
6.00E-02
8.00E-02
1.00E-01

X-displacement contours-1.50E-01-1.00E-01-5.00E-02
0.00E+00
5.00E-02
1.00E-01

Contour interval= 2.00E-02

Contour interval= 5.00E-02

Groundwater level(GL) -1m

GL -1my-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

y-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

Max. shear strain increment
0.00E+00
1.00E-02
2.00E-02
3.00E-02
4.00E-02
5.00E-02
6.00E-02
7.00E-02
8.00E-02

X-displacement contours-1.50E-01-1.25E-01-1.00E-01-7.50E-02-5.00E-02-2.50E-02
0.00E+00
2.50E-02
5.00E-02
7 50E 02

GL -3mGL -3m5

y-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

y-6.610E+00 <x< 1.225E+02-4.961E+01 <y< 7.945E+01

Max. shear strain increment
0.00E+00
1.00E-02
2.00E-02
3.00E-02
4.00E-02
5.00E-02
6.00E-02
7.00E-02

X-displacement contours-1.50E-01-1.25E-01-1.00E-01-7.50E-02-5.00E-02-2.50E-02
0.00E+00
2.50E-02
5.00E-02

Contour interval= 1 00E 02

GL -6mFigure 20.Shear strain increment

GL -6mFigure 21.Horizontal displacements

5. CONCLUSIONSIn order to evaluate the seismic damage mechanism of residential fill ground, field survey using
surface wave exploration, mechanism analysis by FLAC software have been carried out on two
residential fill ground in the eastern part of Kyoto basin. Some remarkable conclusions are
summarized as follows:(1) In Jyodo-ji area, it is fill land on soft ground. The geological condition is back swamp.
It is former farmland changed into residential land. The seismic simulation results show that the shear
strain accumulates in the soft sediment. Sliding arc surface generates in upper part of the ground. Highpore pressure generates and the acceleration amplification occurs during the earthquake. The analysis
results are coincident with the real disaster condition.
(2) In Kiyomizu-dera area, it is residential fill ground in hilly area. The geologicalcondition is hilly platform. Despite this area suffered almost no damage during the 1995 Kobe
earthquake, some cracks can also be seen on the walls of houses in newly developed fill ground. The
analysis results show that the shear strain band accumulates in the ground. Fill soil parts have larger
shear strain and displacements.
(3) With the groundwater level increasing, the acceleration amplification ratio slightly
decreases, but the shear strain band and displacement zone becomes larger.

ACKNOWLEDGEMENT
I would like to express my sincere and heartfelt gratitude to the adviser Dr. Shin KOYAMA from
Building Research Institute for his guidance, support and encouragement during my study.

REFERENCES
Itasca, 2005, FLAC manual – Theory and Background. Minneapolis.
Kamai, T., 1995, Journal of the Japan Society of Engineering Geology, 36-1.
Kamai, T., 2005, Journal of Japan Society of Engineering Geology, 46(3):138-144.
Kamai, T., 2008, Japan Society of Natural Disaster Science, 27(2):189-198.
KG-NET, 2008, Ground information database of Kannsai circle 2008 edition CD-ROM.
Nakagawa. H., 1986, The geological society of Japan. 10:233-239.
Nakamura, Y., 1996, Waveform and its analysis of the 1995 Hyogo-Ken-Nanbu Earthquake(II), JR
earthquake information NO.23d.
Okimura, T., Torii, N., etc, 2006, City safety research center of Kobe university, Research report,
2006(10).
Uemura, Y., 1999, Seismic environment of Kyoto city.
Uemura, Y., 1996, The cause of residential house seismic damage in the surrounding area of Kyoto
during Hyogo-Ken-Nanbu earthquake. Fault research data center
Yoshida, N., et al. 2001, Natural Hazards 23: 87–97.

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