(1)Dam Earthquake Engineering

8/6/2019 (1)Dam Earthquake Engineering

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Yoshikazu YAMAGUCHI

Team Leader, Dam Structures Research TeamHydraulic Engineering Research Group

Public Works Research Institute

Dam Earthquake Engineering


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Seismic Design of Dams

Dam Structures Research TeamHydraulic Engineering Research Group

Public Works Research Institute

Dam Earthquake Engineering


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1. Geological Condition2. Earthquake Observation System

3. Past Earthquakes4. Seismic Design of Dams5. Advanced Seismic Design of Dam

Contents


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Geological Condition


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Location of earthquakes occurred

in the world

JAPAN


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Location of earthquakes occurred

in Japan


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Plate tectonics

EurasiaPlate

PhilippinePlate

Pacific

Plate

trench

Nankai t

rough

Sagamitrough

Japan

trenc

h

Izu-Ogasawaratrench

Chish

ima

trenc

h


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Earthquake types

Ocean PlateLand Plate

Movement of PlateSeveral centimeter per year

Compression force

Inland Type Trench Type

Fault


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Active Faults in Japan


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Earthquake Observation System


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Definition of earthquake size

by Japan Meteorological Agency (JMA)

JMA operates a network made up of about 180 seismographs for continuous

earthquake monitoring and 650 Seismic Intensity Meters, together withSeismic Intensity Meters of about 2000. The observational data are collectedby the Earthquake Phenomena Observation System (EPOS) at theHeadquarters of JMA and the Earthquake and Tsunami Observation System

(ETOS) at the District Meteorological Observatories. As soon as an earthquakeoccurs, EPOS/ETOS processes the observational data to locate the

epicenter

and to determine the magnitude.

After the occurrence of earthquake JMA quickly announces information on

epicenter, magnitude and the distribution of seismic intensity to the publicthrough mass media as well as to the disaster prevention organizations.

It also

provides these observational data for the International Seismological Centre(ISC) in the UK which collects and analyzes seismic observational data over

the world.


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JMA Seismic Intensity ScaleJMA Scale Explanation

7In most buildings, wall tiles and windowpanes are damaged and fall. In

some cases, reinforced concrete-block walls collapse.

6UpperIn many buildings, wall tiles and windowpanes are damaged and fall. Most

unreinforced concrete-block walls collapse.

6lower In some buildings, wall tiles and windowpanes are damaged and fall.

5UpperIn many cases, unreinforced concrete-block walls collapse and tombstonesoverturn. Many automobiles stop due to difficulty to drive. Occasionally,

poorly installed vending machines fall.

5lowerMost people try to escape from a danger. Some people find it difficult to

move

4Many people are frightened. Some peolpe try to escape from a danger.

Most sleeping people awake.

3 Felt by most people in the building. Some people are frightened.

2 Felt by many people in the building. Some sleeping people awake.

1 Felt by only some people in the building .

0 Imperceptible to people.


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Earthquake Observation Systems

Strong Motion Seismograph Network

National Research Institute For Earth

Science and Disaster Prevention

KiK-net (Rockfoundation)

K-net (Surface of ground)


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Online Earthquake Observation

Systems for Dams

NILIM (Tsukuba)

Earthquake Data

Headquaters of MLIT(Tokyo)

Dam Office

Real Time

Database

About 60 dams areconnected on line now.In the future, 410 dams

will be connected.

Seismographs


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Past Earthquakes


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Recent Major Earthquake Disasters

in Japan

Date Earthquake MagnitudeNumberof Lostpersons

Oct. 28, 1891 Nobi Earthquake 8.0 7,273

June 15, 1896 Sanriku Earthquake and Tsunami 8 1/2 22,072

Sept. 1, 1923 Great Kanto Earthquake 7.9 142,807

Mar. 7, 1927 Kitatango Earthquake 7.3 2,925Mar. 3,1933 Sanriku Earthquake and Tsunami 8.1 3,064

Sept. 10, 1943 Tottori Earthquake 7.2 1,083

Dec. 7, 1944 Tonankai Earthquake 7.9 998

Jan. 13, 1945 Mikawa Earthquake 6.8 1,961Dec. 21, 1946 Nankai Earthquake 8.0 1,330

June. 28, 1948 Fukui Earthquake 7.1 3,796

May 26, 1983 Central Japan Sea Earthquake 7.7 104

July 12, 1993 Southwest of Hokkaido Earthquake 7.8 230

Jan. 17, 1995 Southern Hyogo Prefecture Earthquake 7.2 6,427

Oct 6, 2000 Western Tottori Prefecture Earthquake 6.6


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Hyogo-ken Nambe (Kobe) Earthquake

Date : 17 Jan 1995 am 5:46

Epicenter : 3436 North Latitude13502 East Longitude

Focal Depth : 16 km

JMA Magnitude : 7.3


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Distribution of Seismic Intensity

Epicenter


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Location of Nojima Fault

Osaka

Nojima Fault

Kobe


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Photo 1

Collapse of Highway Overpass


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Photo 2

Collapse of Buildings


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Photo 3

Appearance of Nojima Fault


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Location of Dams near the Epicenter

About 50 dams exist within 50 km from the epicenter


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Special Safety Inspections of Dams

Primary Inspection

Visual Inspection immediately after the earthquakeSecondary Inspection

Both a detailed visual inspection andsafety checks of data recorded by instruments

The special safety inspection of 251 dams werecompleted by January 21, 1995

(occurrence of the earthquake was Jan. 17)

No damage requiring emergency protective

countermeasures was reported.


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Horizontal Accelerations observed at

dam sites


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Acceleration Response Spectrum


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Relationship between the Distance and

the Horizontal Accelerations


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the Vertical Accelerations


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the Horizontal Accelerations (Soil Sites)


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FEM Analysis (Concrete Gravity Dam)


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Results of FEM Analysis

(Concrete Gravity Dam)


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Results of FEM Analysis

(Concrete Gravity Dam)


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Conclusions of Dam Safety Evaluation

during Hyogo-ken Nambu Earthquake

The special safety inspections by site officers and detailedinvestigations (using dynamic analyses) by PWRI engineersconfirmed that there was no serious damage affecting damsafety or requiring protective countermeasures.The dams were constructed on the rock foundations wherethe earthquake motion were substantially smaller than thoseat soil sites. It is one of major reasons why dams were safe

during the earthquake.Careful geological investigation and site location, adequatesafety factor in designing dams, high-quality construction

were also important to ensure the safety of dams.


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Seismic Design of Dams


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Essentials of a design

The dam shall be of a structure possessingsafety under anticipated loads, the necessary

durability and watertightness, and good operatingproperties. Also, It should be designed withconsideration to its economics.


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Essentials of Design

A Concrete Dam should have such a structure thatwill not slide or overturning under the estimated loads.

An Embankment Dam should have such a structure

that will not show sliding or seepage failure under theestimated loads.

Foundations for dams should be safe from sliding,or seepage failure under the estimated loads.


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Difference in Design Methods

in accordance with Dam Types

Type ofDams

BasicAssumptions

Conditions ofDam Design

ConcreteGravity

Dams

ConcreteArch

DamsEmbankmentDams

2-DimentionalElastic Body

3-DimentionalElastic Body

2-DimentionalNon-Elastic Body

1) Middle third condition2) Hennys formula (Fs4)

3) Allowable stress

1) Allowable stress2) Hennys formula (Fs4)

1) Sliding method(Fs1.2)


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Design Water Levels

Concrete Dam Embankment Dam

SWLNWL

DFL

LWL

SWLNWL

DFL

LWL

MWL

Empty Empty

Drop rapidly


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Design Loads (2)

Reservoir condition Concrete Gravity Dam Concrete Arch Dam Embankment Dam

Middle water level Self weightHydrostatic pressure

Pore pressure

Inertia forceWhen the water level

drops rapidly

Empty reservoir

Self weight

Inertia force

Self weight

Inertia force

Self weight

Pore pressure

Inertia force


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Seismic Loads

Concrete Dam Embankment Dam

Inertia Force Inertia ForceHydrodynamicpressure

Seismic Coefficient Method


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Inertia Force

I = WkWhere,

I inertia force of the dam body duringan earthquakeW weight of dam bodyk design seismic coefficient


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Hydrodynamic Pressure

Where,

Pd hydrodynamic pressurehHkWPd w 875.0=

Ww unit weight of waterk design seismic coefficientH depth of the reservoir

h

depth of the water from the water surface


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Hydrodynamic Pressure

H

h

Pd

2

0)(

12

7HkW

dyPdH

w

H

dynamicw

=

=


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Advanced Seismic Design of Dam


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Advanced Seismic Design

Modified Seismic Coefficient Method

Dynamic Analysis using FEM


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SeismicCoefficient

Method

ModifiedSeismicCoefficientMethod

Distribution of Seismic Coefficient k


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1991.6 SEISMIC DESIGN STANDARD FOR

EMBANKMENT DAMS (DRAFT)

0.0 1.0 2.0 3.0

0.0

0.2

0.4

0.6

0.8

1.02.51.4

k/kf

y/

H

1.76

Hy


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Example of Dynamic AnalysisOct 6, 2000 Western Tottori Prefecture Earthquake

Kasho Dam

Kasho DamEpicenter


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Earthquake Record (Input Data)

20.480

0.010 -503.345 5.930

-500.0

-250.0

0. 0

250.0

500.0

ACCELERATI

ON

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0

20.480

0.010 485.209 6.680

-500.0

-250.0

0. 0

250.0

500.0

ACCELERATION

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0

Horizontal

Vertical


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Dynamic Analysis using FEM

Principal Stress(Tension)

Principal Stress

(Compression)

X

Y

Z

-7.3479

-183.59

0.

-10.

-20.

-30.

-40.

-50.

-60.-70.

-80.

-90.

-100.

-110.

-120.

-130.

-140.

-150.

-160.

-170.

-180.

-190.

V1L1G1

Output Set: PLAN-S3Contour: PLANE S3

X

Y

Z148.86

5.1191

150.

140.

130.

120.

110.

100.

90.

80.

70.

60.

50.

40.

30.

20.

10.

0.

V1L1G1

Output Set: PLAN-S1Contour: PLANE S1

N Li D i A l i


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Non-Linear Dynamic Analysis

using FEM


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Role of Dynamic Analysis

Design Inspection

Seismic Coefficient Method

Modified SeismicCoefficient Method

Unique solution can beobtained.

Dynamic Analysis usingFEM, BEM, DEM

Results are effected bymethod, model,conditions


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Definition of Earthquake Motions

Level I Earthquake motions is the level in which structuresare not damaged when these motions strike.(OBEOperation Based Earthquake)

Proposal of Earthquake Resistance for Civil Engineering Structures

by Japan Society of Civil Engineering

Level II Earthquake motions is the level in which an ultimatecapacity of earthquake resistance of a structure isassessed in plastic deformation range.(MCEMaximum Credible Earthquake)

A structure is designed so that it may not get damage

A structure is designed so that it may not get fataldamage

Documents

(1)Dam Earthquake Engineering