3. Earthquake Engineering
3.1. Evaluation of Ground Damage
Basic Terminology:
Damage: Collapse, slip, crack, subsidence, undulation and inclination of ground,which includes retaining wall, caused by an earthquake.
Damage grade: Grade of damage by ground conditions after an earthquake.
Restoration: Repair the crack and the subsidence, etc. of ground due to an
earthquake and recover the ground to the condition before an earthquake.
Retrofit: Secure necessary ground strength by reinforcing the ground where thestrength decreased due to an earthquake, and enable to reuse.
Safety: The ground conditions which ensure the safety of human life and building
conditions even at a possible severe earthquake.
Purpose:
Methodology of an evaluation of safety on ground condition after earthquake ortsunamiImportant Points:
Timing::Timing

Evaluation Methodology

Immediate・First announcement of

Example・Reports of eye witness & Feelings

damage of ground・Damage overview indamaged area
・Quick inspection
Within few days
・Damage survey in a typicalarea
Within few weeks ・Damage Classification

by local habitants
・Broadcast

After several
months・Retrofit method and design

・Investigation for retrofit

・Judgment of off-limits or

emergency retrofit
・Judgment of need to retrofit or not

Grade:
Grade
Minimum Necessary
BetterBest

Methodology

MeasuresReports of eye witness & Feelings Information to habitants
by local habitants
Instant evaluation
Restoration of damage area
Retrofit of damage area
Evaluation on ground safety
Retrofit of damage area67

3.1.1. Damage investigation flow chart
The flow chart of ground damage investigation is presented in Figure 3.1.1-1.
The ground damage investigation may be classified into two types: one that concerns theground in a broad area and the other that is limited in scope to the ground in each building
site.
"Quick Inspection" of the ground is made within two or three days after anearthquake, with emphasis placed on the more seriously damaged ground. The purposes are toa) judge whether it is necessary to take measures such as preventing people from entering or
evacuating the residents, b) determine if emergency repair and reinforcement is needed, c)determine whether the current ground should be maintained, and d) when the current groundis maintained, the necessity of repair or reinforcement is judged according to "Damage GradeClassification" that is conducted within several weeks.
In cases where repair or reinforcement is needed to restore the ground, either the
restoration method is selected or the restoration design is investigated. The method is decided
several weeks to several months after the earthquake. But when the ground is judged
impossible to restore, the use of the area in question has to be reconsidered.
When such measures as forbidding people from entering or evacuating residents
from the ground are taken, either the restoration of the ground is investigated with a view toreusing it for the same purpose as before, or its restoration is abandoned and the category ofusage, including new application, of the area in question is considered anew.
For the details of the liquefaction map, refer to materials listed under the headingof "Zoning for Soil Liquefaction" in the reference section.

68

START
Earthquake

2～3 days after
Earthquake

First Step Disaster Survy（Target is large dameges）
Off-limits
orEvacuation
Not
Re-UseJudgment of the
Quick Inspection

Presenceof Re-Use

Emergency
Repair, Retrofit

Keep to a present state
Second Step Disaster Survy（Investigation to confirm necessity ofrepair and retrofit）

Re-UseNeeded Retrofit
Not Need Third Step
Disaster Survy

Judgment of theDamege GradeClassification

Sevral Weeks
after
Earthquake
Not Needed
Retrofit

Needed Retrofit

Third Step Disaster Survy（Investigation for decision of retrofit methodor
Investigation for retrofit design ）Sevral Months
after
Earthquake

Not possilbe retrofit
Usage change（Park, Green bellt etc.）

Not possilbe retrofit

Judgment ofretrofit method

END
Quick Inspection sheet
Judgment of Damage Grade Classification sheet

Fig. 3.1.1-1 Damage Investigation Flow of Ground[1]693.1.2. Quick inspection
The quick inspection of the ground is done to prevent any secondary damages
from occurring. The purpose of this inspection is to determine a) whether it is necessary totake such measures as prohibiting people from entering or evacuating residents and b)
whether the area is in need of emergency repair and reinforcement.
Example 1(Table 3.1.2-1) shows a quick inspection sheet for the ground in a
broad area. Example 2(Table 3.1.2-2) shows such a sheet for the ground in each building site.
The inspection should be made on the site as a rule; however, aerial photographs, videos, andsimilar methods may be used when various factors do not allow inspectors direct access to thesite.

3.1.3. Damage classification
When the judgment made by the quick inspection of the ground in 3.1.1 c) is thatthe ground should be maintained, the area’s damage grade classification is determined toreflect the amount of damage. It is also determined whether repair and reinforcement isneeded. Example 3(Table 3.1.3-1) shows a judgment of damage grade classification sheet for
the ground in a broad area. Example 4(Table 3.1.3-2) shows such a sheet for the ground ineach building site. For the ground in a broad area, attention should be paid also to the post
inspection development of its damage.

Reference
1. Quick inspection & Damage Classification of Ground[1] “Criterion on damage classification and guideline to restoration of buildings damaged byearthquake.” Post earthquake damage inspection sheet for building area, The Japan
Building Disaster Prevention Association, 1991 February. (in Japanese)
2. Zoning for Soil Liquefaction[2] Ishihara, K. : Stability of Natural Deposits during Earthquakes, Proc., 11th Int. Conf. on
Soil Mechanics and Foundation Engineering, San Francisco, Vol. 1, pp. 321-376, 1985.
[3] Ishihara, K. and Ogawa, K : Liquefaction Susceptibility Map of Downtown Tokyo, Proc.,
2nd Int. Conf. on Microzonation, San Francisco, Vol.2, pp.897-910, 1978
[4] Iwasaki, I., Tokida, K., Tatsuoka, F., Watanabe, S., Yasuda, S. and Sato, H. :Microzonation for Soil Liquefaction Potential Using Simplified Methods, Proc., 3rd Int.
Conf. on Microzonation, Seattle, Vol. 3, pp. 1319-1330, 1982.
[5] Iwasaki, T., Tatsuoka, F., Tokida, K. and Yasuda, S.: A Practical Method for Assessing
Soil Liquefaction Potential Based on Case Studies at Various Sites in Japan, Proc. 2nd mt.
70

Conf on Microzonation, San Francisco, Vol. 2, pp. 885-896, 1978.
[6] Kuribayasi, Tatsuoka : Brief Review of Soil Liquefaction During Earthquake in Japan,
Soils and Foundations, Vol.15, No.4, pp81-92,1975.
[7] Kotoda, K., Wakamatsu, K. and Oya, M.: Mapping Liquefaction Potential Based on
Geomorphological Land Classification, Proc., 9th World Conf. Earthquake Engineering,Tokyo, Vol. 3, pp. 195-200, 1988.
[8] Seed, H.B. and Idriss, I. M.: Simplified Procedure for Evaluating Soil Liquefaction
Potential, J. SMFD, ASCE, Vol. 97, No. 9, pp. 1249-1273, 1971.
[9] Seed, H.B. and De Alba, P. (1986). Use of SPT and CPT Tests for Evaluating the
Liquefaction Resistance of Sands, Proc., In Situ '86, ASCE, pp. 281-302, 1986.
[10] Seed, H.B., Tokimatsu, K., Harder, L.F. and Chung, R. M. : Influence of SPT
Procedures in Soil Liquefaction Resistance Evaluation, J. GED, ASCE, Vol. 111, No. 12,
pp. 1425- 1445, 1985.
[11] Tokimatsu, K. and Yoshimi, Y. : Empirical Correlation of Soil Liquefaction Based on
SPT N-value and Fines Content, Soils and Foundations, Vol. 30, No. 3, pp. 153-158,
1983.
[12] Wakamatsu, K : Maps for Historic Liquefaction Site in Japan, Tokai University Press,
1991[13] Youd, T.L., Nichols, D.R., Helley, E.J. Lajoie, K.R. : Liquefaction Potential, Studies for
Seismic Zonation of San Francisco Bay Region, Geological Survey Professional Paper
941-A, pp.A68-A74, 1975.
[14] Youd, T. L. and Perkins, D. M. : Mapping of Liquefaction Severity Index, I. GED,
ASCE, Vol. 113, No.ll, pp. 1374- 1392, 1987.
[15] Youd, T.L. and Perkins, D.M. : Mapping of Liquefaction Induced Ground Failure
Potential, J. GED, ASCE, Vol. 104, No.4, pp. 433-446, 1978.

71

Example 1

Table 3.1.2-1 Quick Inspection Sheet for Ground[1]

Sheet 1/3

Sheet No.
Time&Date
RecoderSite adress
Damage patern□ [A]: Collapse of fill-up groundkind of fill-up groundterracedothers(m)Collapsing width:(m)Collapsing length:
Collapsing azimuth:
Is there a housing lot in the vicinity of collapse ground□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [B]: Collapse of hillback slope
kind of hillback slope
natural slope
cutting slope(m)Collapsing width:(m)Collapsing length:
Collapsing azimuth:(deg)Inclination of slope:
Surface condition of slope:□Weed□Mortar□Turf□TreeIs there a building area in the vicinity of collapse ground?
□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others

72

Example 1 (Cont.)
Sheet 2/3
□ [C]: Collapse or Fall of Retaining Wall
Hight of Retaining Wall
Type of Retaining WallCollapsing width:
Collapsing length:
Collapsing azimuth:
Is there a housing lot in the vicinity of damage retaining wall
□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [D]: Crack and Step
The generation points are filled in on figure.
Width of Crack or Step(m)
Length of Crack or Step(m)
Depth of Crack or Step(m)
Range of Crack(m2)
Is there a building area in damage region?
□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [E]: Settlement , Inclination, Undulation and movement of retaining wall
The generation points are filled in on figure.
Damage hight(m)
Damage length(m)
Damage width(m)Is there a building area in damage region?
□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others73

Example 1 (Cont.)
Sheet 3/3
□ [F]: Watter
The generation points are filled in on figure.
Volume of water:□ Disorder, □ Usual□ [Yes], □ [No]Past situation:
Liquifaction:□ [Yes], □ [No]□ [Yes], □ [No]Outflow of gas:
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others
Damage patern
Sketch of damage situation
FailureSettlement
Upheaval
Spring water
Displacement
Step
Crack
House
Retaining wall
Slope
Ｓ

Emergency action isnecessary

Filling in recoder's opinion
Is there a house thought that shelter is necessary in the surrounding?
orIs there a house thought that off-limits is necessary in the surrounding?
□ [Yes], □ [No], □[Not possible to judge]
Is there a place where the emergency repair (or retrofit) are necessary?
□ [Yes], □ [No], □[Not possible to judge]
Maintenance of current state

Others74

Example 2

Table 3.1.2-2 Quick Inspection Sheet for Building Area Ground[1]

Sheet 1/3

Sheet No.
Time&Date
RecoderSite adress
Damage patern□ [A]: Collapse of slope
kind of slope
natural slope
cutting slope

enbankment slope
Damage scale□Large, □Medium, □Small(m)
Collapsing width:(m)Collapsing length:
Collapsing azimuth:(deg)Inclination of slope:Distance to Building:(m)
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [B]: Collapse or Fall of Retaining Wall
Back ground material
cutting ground material
enbankment ground material
Damage scale□Large, □Medium, □Small
Collapsing width of Retaining Wall :Collapsing length of Retaining Wall:Collapsing azimuth:
Distance to Building:(m)
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others

75

Example 2 (Cont.)
Sheet 2/3
□ [C]: Crack and Step
Damage scale□Large, □Medium, □Small
Width of Crack(m)
Length of Crack(m)
Depth of Crack(m)
Generation Points
Sloop,
Retaining WallDistance to Building:(m)
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [D]: Inclination, Undulation and movement of retaining wall
The generation points are filled in on figure.
Damage scale□Large, □Medium, □Small
Damage length(m)
Damage width(m)
Damage hight(m)
Distance to Building:(m)
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [E]: Settlement , Burying and Upheaval of GroundThe generation points are filled in on figure.
Damage scale□Large, □Medium, □Small
Damage hight(m)
Damage length(m)
Damage width(m)
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others

76

Example 2 (Cont.)
Sheet 3/3
□ [F]: Spring water
The generation points are filled in on figure.
Volume of water:□ Disorder, □ Usual
Liquifaction:□ [Yes], □ [No]□ [Yes], □ [No]Outflow of gas:
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others
Damage patern
Sketch of damage situation
FailureSettlement
Upheaval
Spring water
Displacement
Step
Crack
House
Retaining wall
Slope
Ｓ

Emergency action isnecessary

Filling in recoder's opinion
Is there a place where the shelter (or off-limits) is necessary?
□ [Need]□ [Not Need]□[Not possible to judge]
Is there a place where the emergency repair (or retrofit) is necessary?
□ [Need]□ [Not Need]□[Not possible to judge]
Maintenance of current state

Others77

Example 3

Sheet 1/3

Table 3.1.3-1 Judgment of Damage Grade Classification Sheet for Ground[1]

Sheet No.
Time&Date
RecoderSite adress
Damage patern□ [A]: Collapse of fill-up groundkind of fill-up groundterracedothers(m)Collapsing width:(m)Collapsing length:
Collapsing azimuth:
Number of collapse housing lots
Is there a building area in the vicinity of collapse ground?
Numbers of housing lots
□ [Yes]□ [No]
Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [B]: Collapse of hillback slope
kind of hillback slope
natural slope
cutting slope(m)Collapsing width:(m)Collapsing length:
Collapsing azimuth:(deg)Inclination of slope:
Surface condition of slope:□Weed□Mortar□Others□Turf□Tree
Number of outflow building area :Number of burying building area :Number of building area in surrounding :Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others

78

Example 3 (Cont.)
Sheet 2/3
□ [C]: Collapse or Fall of Retaining Wall
Hight of Retaining Wall
Type of Retaining WallCollapsing width:
Collapsing hight:
Collapsing length:
Collapsing azimuth:
Number of outflow building area :Number of burying building area :Number of building area in surrounding :Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [D]: Crack and Step
The generation points:
Width of Crack or Step(m)
Length of Crack or Step(m)
Depth of Crack or Step(m)
Range of Crack or Step(m2)
Number of building area in damage region :Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others□ [E]: Settlement , Inclination, Undulation and movement of retaining wall
The generation points:
Damage hight(m)
Damage length(m)
Damage width(m)
Number of building area in damage region :Investigation method□ by watching□ by video□ by scaling□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others

79

Example 3 (Cont.)
Sheet 3/3
□ [F]: Watter
The generation points:
Volume of water:□ Large amount, □ Midlle amount, □ Oozes out□ [Yes], □ [No]Past situation:
Liquifaction:□ [Yes], □ [No]□ [Yes], □ [No]Outflow of gas:
Investigation method□ by watching□ by measurement□ others
Soil type□ Sand, □ Loam, □ Viscous soil , □ Gravel, □ Others
Damage patern
Sketch of damage situation
FailureSettlement
Upheaval
Spring water
Displacement
Step
Crack
House
Retaining wall
Slope
Ｓ

Emergency action isnecessary

Filling in recoder's opinion
Is there a place where the repair (or the retrofit) are necessary?
□ [Need]□ [Not Need]□[Not possible to judge]
Progress situation of damage□ [Change], □ [No change]
Necessity of movement observation□ [Need], □ [No need]
Others80

Example 4

Sheet 1/4

Table 3.1.3-2 Judgment of Damage Grade Classification Sheet for Building Area Ground [1]Sheet No.
Time&Date
RecoderSite adress
Damage patern and content□ [A]: Slope failure
Kind of slope□ cutting slope□ enbankment slope□ natural slope(m)Hight of slope(H):(deg)
Inclination of slope:Azimuth of slope:(m)Collapsing slope width(B):(m)
Collapsing slope length(L):Distance to Building(S):(m)
Caluculation of damage grade index R1 or R3s
R1=( H x B x L )/( S + 1)…(Eq. - 1)
R1 =or
R3s=( H x (B+1) x (L+1))/(S + 1)
R3s=
Evaluation of damage grade index point P1 or P3s
R1 or R3s
50=< R1 or R3s
25<R1orR32<50
R1 or R3s <= 25
Investigation method

P1
9
6
3

P3s
6
4
2

P1 =
P3s=

□ by watching□ by video□ by scaling□ others

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others□ [B]: Collapsing or Over turnning of Retaining Wall
Type of Retaining Wall

Hight of Retaining Wall (H):(m)(m)
Collapsing or Over turnning retaining wall width((m)
Collapsing or Over turnning retaining wall length
Distance to Building(S):(m)
Caluculation of damage grade index R2
R2 = B x L…(Eq. - 2)R2 =R3w=(B+1) x (L+1)
R3w=
Evaluation of damage grade index point P2 or P3w
R2 or R3w
20=< R2 or R3w
10<R2orR3w<20
R2 or R3w <= 10
Investigation method

P2
9
6
3

P3w
6
4
2

P2 =
P3w=

□ by watching□ by video□ by scaling□ others

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others

81Example 4 (Cont.)
Sheet 2/4
Damage patern and content□ [C]: Occurrence of Crack
Place of Crack□ Slope□ Retaining Wall
□ Building area
Width of Crack (B):(m)
Length of Crack (L):(m)(m)
Depth of Crack:
Distance to Building(S):(m)(m)
Hight of slope(H):Caluculation of damage grade index and Evaluation of damage grade index point
Slope
R3s=( H x (B+1) x (L+1))/(S + 1)
R3s=
P3s=
Retaining Wall
R3w=(B+1) x (L+1)
R3w=
P3w=
Building Area2
R3g=
R3g=(B+1) x (L+1)=
m
R3g
P3g
P3g=
150 =< R3g
3
50<R3g<150
2R3g <= 50
1
Investigation method□ by watching□ by video□ by scaling□ others

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others□ [D]: Inclination, Moving, Undulation of Retaining Wall
Damage type
□ Inclination□ Moving□ Undulation
Width of Damage(B)(m)(m)
Length of Damage(L)(m)
Hight of Damage(H)(deg)
Degree of Inclination
Amount of movement(mm)
Distance to Building(S):(m)
Damage grade index and Evaluation of damage grade point
R4
Undulation
Inclination
MovingInvestigation method

P4
3
2
1

P4 =

□ by watching□ by video□ by scaling□ others

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others82

Example 4 (Cont.)
Damage patern and content□ [E]: Settlement , Burying and Upheaval of Ground
Damage type
□ Settlement□ Burying□ Upheaval
Damage scale
Width of damage(B)(m)(m)
Length of Damage(L)Settlement or Upheaval (H)(m)
Damage grade index and Evaluation of damage grade point
R5 = B x L x H =R5100 =< R5
50 < R5 < 100
R5 =< 50

m2

P5
3
2
1

Investigation method

P5 =□ by watching□ by video□ by scaling□ others

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others□ [F]: Spring water such as liquifaction
Liquifaction:□ [Yes], □ [No]sand boil□ [Yes], □ [No]Amount of spring water□Many, □few, □blots begin
Past spring water situation □ [Yes], □ [No]Generation points
Damage grade index and Evaluation of damage grade point
R6
Soft ground
Spring water
Investigation method

P6
2
1

P6 =

□ by watching□ others□ by measurement

Soil type□ Sand, □ Loam, □ Cohesive soil , □ Gravel, □ Others□ [G]: Others

83

Sheet 3/4

Example
4
Damage pattpattern and content
Sketch of damage situation

Sheet 4/4

FailureSettlement
Upheaval
Spring water
Displacement
Step
Crack
House
Retaining wall
Slope
Ｓ

Emergency action isnecessary

Evaluation of damage
P = P1 + P2 + P3 + P4 + P5 + P6
P=
( P3 = P3s + P3w + P3g ) Evaluation of damage
Total point P Damage level
10 =< P
Large damage
6 < P < 9 Middle damage
P =< 5
Small damage84