Japanese National Committee on Large Dams. Dams in Japan, No. 10

1. Outtine

of the

project

The

Azusa River Project includes

three arch dams, named

Nagawado, Midono

and Inekoki,

and three

power plants in-

cluding pumped-storage

power

plants with

total maximum

output

capacity of 900 MW.

(see

Figure 1)

The

main structures of the

project are Nagawado Dam and

Azumi

pumped-storage

power

plant

with maximum

output

capacity of 623

MW.

2. Geology

of

the

dam site

The foundation rock at the dam site consists

of three kinds

of rock, that

is

granite,

homfels and lamprophyre.

(see

Fi-

gure

2) Some systems of dislocated

planes

and

joints

exist in the

foundation rock,

and

the most

remarkable strike

and dip

amonq them is

around N83'W,?8'NE.

ShinE,ino&ni

Riyer

Dan

fgtirEiinodni

PS

t

rRlstimo

pS

grinrtushirm

Fig.

I

PROFILE

OF

AZUSA

RMR

PROJECT

I ooo

(m)

66

,

-tt

f

t*PS

(imPro,"o)

X

I

d

I

X

x[All{llxlxxx

x f>df I fx l'l

xl

x x

NOTE

[r7l

cnnru tre

Fl

Hspxs6r_5

ffi

uaupRopHyRE

@

rautt

Fig.2

GEOLOGICALPROFILE

Systems of almost vertical

faults are developed in the

granite foundation rock on both banks,

roughly in

parallel with

the

river valley; therefore,

the symmetric axis of the

dam was arranged nearly

parallel

to the ver in

order

that the dam

thrust would

have almost equal effect upon the foundation of

both abutments.

3.

Design of

the dam

In addition

to stress analysis on the arch dam, model

tests

were

conducted to

check

the result of numerical analysis,

and

to determine

the final shape of the dam and the method

of

foundation treatment.

4.

Foundation

treatment

The fault

treatment by concrete replacement

was done for the

prominent faults to ensure necessary

stabilization,

to

control

the deformation and reduce the

permeability

of

the foundation.

Furthermore a

prestressing

system

using high-

tension

steel rods was

applied

to the foundation rock mass

which rnight be

partly loosened

by the stress release

du ng the

fault excavation.

(1)

Excavation

by high

pressure water

The

excavation of the faults was carried out by

using machines

with 1.5-24mm nozzles ejecting a

water

jet

stream

approximately 2m3lmin

under

lo0kgflcmz

pressure,

because

conventional excavation

method using dynamite

would

tend

to

weaken

the sound rock around the faults.

The volume of fault materials excavated by

iet

water

was about 13,400mr.

(2)

Concrete

placing

and

grouting

After

the fault excavation,

concrete was

placed

immediately.

The total volume of concretc used to replac€

the fault

materials

amounted to about 30,000m3.

(see

Figure 3)

After concrete placing, consolidation

grouting was executed

in the surrounding

rocks of the

faults.

(3)

Prestressing reinforcement for abutment

171 holes, 150mm in diameter

and 40-90m deep,

were

drilled into the rock

mass of the abutment.

(see

Figure

4)

The

steel rods were anchored

with cement mortar

on the inside

end of the hole

about 6m lorig. The tension

was 24O tonf

a hole and about 40,000 tonf in total,

and the total

volume of the

prestressed rock mass was nearly 250,000mr.

:_-A!.t_s_?o.ooo

PLAXE

:---DrL--€!!,_90e_

K.J

I

Fig. 3

FAULT

TREATMENT

EL.87Z

OOO

GROUT CURTAIN

DRAINAGE

HOLE

FAULT

____-=I

STEEL

ROD

Fig.

4

PRESTRESSING

REINFORCEMENT

FOR

ABUTMENT

SECTION

A

-A

6l

2I

.

NARUGO

DAM

Location

Nearest

City .

River

Purpose

Catchment

area

Mean

annual

discharge

Years

of construction

.

Type

Foundation

Height

Crest length

Volume

Spillway

Type

and

number

of

gate ..

Maximum

discharge

capacity

Reservoir

Gross

capacity

Effective

capacity

Area

Drawdown

range

Owner

Engineering

by

Construction

by

Narugo-cho,

Tamatsukuri-gun,

Miyagi-ken

Furukawa-shi

Eai

Flood control, Irrigation

and Hydroelectric

210km'?

13.8m3/s

1952-t957

Arch

Granodiorite

95m

215m

180,000m'

Controlled/Uncontrolled

Orifice

fixed

roller

gateX2

700m3/s

50X

10um3

35

X

106m3

2.Ikm'

24m

Ministry

of Construction

Ditto

Kajima Corp.

GENERAL

PLAN

Thrusf

Block

)

Narugo Dam is one of the

the oldest arch

dam

in Japan

constructed

by Minishy

of Construction.

It has two

types

ot

spittways, an inclined tunnel

spiuway, the biggest

in lapan

and an

overfaU

spiuway'

-

The dam site forms a

V-shapid

va[ef-and

conrprises

granodiorite and

liparite. Faults

and ftactured

zones

ir the

foundation were

treated

by a

concrete wali

trarsmitting

arch

thrust

into the

sound

rock and

foundation

grouting was

ela-

borately

canied out.

Various kinds of measurements

such as deflection,

stless,

joints

movement

and

temperature

have been

observed

since

its

donstruction.

The collected

data are

not only utilized

for the

dam inspectidn

but also contributed

much

to the technical

advance in designing arch

dams

thereafter.

260m

2so

210

TYPICAL

CROSS SECTION

230

?20

2ro

200

t90

t80

'r70

EL

EmerqencY

SPillwoY

-

/lt

Thrusl

/

!

Elock

,/ I

4o9t--L

(on

Elemenl

Belween

Arch

ond

Abulmenl

UPSTREAM

VIEW

69

22.

ODO DAM

Location

Nearest

City

.

River

Purpose

Catchment

area

Mean

annual

discharge

Years

of construction

.

Type

Foundation

Height

Crest

length

Volume

Spillway

Type

..................

..... Controlled

T5pe

and number

of

gate

......................

Crest mdial

gateX4

and Orifice radial

gateX5

Maximum

discharge

capacity ................. 7,700m7s

Reservoir

Gross

capacity

..........

66

X

lffml

Effective

capacity

...... 52

X

1Cl6m3

Area .................,

.... 2.0km,

Drawdown

range

.,.,............................. 40m

Owner

.............,..

......,.... Ministry of Construction

Engineering

by

............... Ditto

Constructiou

by

Taisei

Corp.

1.. General

Profile

Odo dam

is a concrete

gravity

dam constuucted by Ministy

of Construction. It is located in one

of the heavy

rainfall

territories

in

Japan, where the typhoon ftequently overtake

and total rainfall exceeds

3,500mm

a

year,

so flood control

is

the

most important

aim of the dam.

2. Geology

The

geology

of the darn

site

mainly consists of the Permian

Shirakidani stratum covered with river sediment and talus

materials

of the

Quartemary

period

of the Cenozoic era. The Shirakidani

stratum consists of chert, scharlstein, sandstone

and

Slate, which

are in layer. The scharlstein is the

most

predominent at the dam site. The chert and

sandstone

which

are

hard and

b ttle are especially crushed and sheared.

They are

found in the scharlstein or

slate in the form

of a lens.

The strike aqd

dip of

each stratum

is not uniform due to

the

presence of folding and faults. Faults

are small

in

general,

whose

width

are less than 1m. Cracks develop in

parallel to the

joints

and faults.

Niyodo-mura,

Takaoka-gun,

Kochi-ken

KOchi-shi

Niyodo

Flood

control, Maintenance

of normal

function

of the

river

water.

water

supply and

Hydroelectric

689km'

20.1m3is

196G-1981

Gravity

Schalstein

and Chert

96m

325m

1,000,000m,

__a

\

r

70

PLAN

Design

and

Construction

of the

dam

Main

features

of

the design

and

construction

are as follows,

\

\c9!€9LrO4nS!_-GE9!r-|L

?r

rt50!3r30

GontaY

cronc

_

po

3.

Construction

of large

fillet

at the

upstream

side of the

dam

to increase

bearing

and

shearing

stability.

Installation

high pressure

radial

conduit gates

as

main

outlet

of

which

size

is

the

largest

ones

in

Japan

(5.6m

height,

5.0m

width,

design

water

depth

60m,

5 units)

Flood

flow

is so large

at

the

dam

site that works

of

main

outlets

installation

had

to

avoid

the typhoon

seasons

(July

-

October)

to

prevent

the work

site from

being drowned.

Therefore,

when

it

started

to construct

five

main

out-

let gates,

it was

inevitable

to construct

two

gates

(both

ends)

at first

and

another

three gates

(center)

separately.

;

SECTION

"lr*-r

ll tr'-*o

Il Er-oasF

ll f---

|

il--r\l

-l

l[

ELrzs.o |

\ r f\l

\_-L____________

-,,1 |

(1)

(2)

(3)

€Um)

240

?+--e-*--+...t"

7T

O

rc

JO€

S

-|._

UPSTREAM

VIEW

23.

OGOCHI

DAM

Location

Nearest

City .

River

Purpose

Catchment

area

Mean

annual discharge

Years

of construction

.

Type

Foundation

Height

Crest

length

Volume

Spillway

Type

Controlled

Type

and number

of

gate

..

Roller-gate,

5

Maximum discharge

capacity

1,800m3/s

Reservoir

Gross

capacity

189.1

X

106m3

Effective

capacity

185.4

X

106m3

Area

4.3km'?

Drawdown

range

101.5m

Owner

Tokyo

Metropolitan

Government

Engineering

by

Ditto

Construction

by

Hazama-Gumi,

Ltd.,

Kajima Co., and

Nishimatsu

Construction Co.,

Okutama-cho,

Nishitama-gun.

Tokyo-to

Oume-shi

Tama

Water supply

263km'?

10.2m3ls

1938-1957

Gravity

Greywacke

L49m

353m

1,675,680m3

Ltd.

c

o

E

a

c

o

E

\>

/ ol

(

.3

1

)F

eo-g_

-\9.

---u

-

S

vqF.i

_\r

---

.:

=;

%,

'l,^\

,-i,\

Blonkel Grouting Hole

PLAN

TYPICAL

CROSS

SECTION

Spirol

Sloir Tower

EL

r530

UPSTREAM

VIEW

(1)

Generallnformation

ogdchi

Dam

is aimed

at

meeting

the increasing

demand for

water

supply

in Tokyo.

The

flow

of Tama

River is

con-

trolled

by

the

Og6chi

Dam

constructed

in its

upper reaches to

increase

the

ra\ry water

to be taken

in

for additional

distribu-

tion.up.

to

425,000mr

per

day.

water

from Tama

River is

taken

prirnarily

through

the

Hamura

Intake

weir

located

36km

on

the

lower

course.

The water

taken

from

the dver is conducted

to the

Higashi

Muruy"rnu

r,riiti""iion

plant,

the ozaku

l,{ifi:a-tio-n

Plant

and

the

Murayama

Yamaguchi

Reservoirs.

The

water

stored

at

these reservoirs

is conducted

to the

Hrgasnr

Mumyama

Pu fication

Planr

and the

Sakai

purification

plant.

In

conjunction

with

the

aboYe,

hydro-electric

power

with

three power

plants

and

flood

control

were developed

by the

colstruction

of

the

dam.

In addition

there

are recreation

benefits

around

the reservoir

which

is

named

Lake

okutama.

73

(2)

History

Construction

of the

dam was

started

in

November

of

1938.

It

was

suspended

World

war

II,

and

concrete placing

was

started

in

March

of 1953.

In

July

of

1957,

the

November

of

the

same year

the work

was

completed.

,,

(3)

Treatment

of Foundation

The

foundation

consisting

of

graywackes

with

clay

slates of belt

inteJbedded

in several

places

belongs

to the

upper

Jurassic

Period'

No

faults wire

pirceived

in

the founiation

of

the dam,

but

there could

be

seen

several

fissures

of

rather

consplcuous

natule.

The

amount

of excavation

totalled

approximately

560,400mr.

Grouting

of approximately

54,500m

in total

length

was

executed

in

order

to

establish an effectiv€

barrier

to seepage

and to

consolidate

the foundation

.ock

,rnde,

the

dam,

thus

securing

the

unified

and

monolithic

foundation.

(4)

Concrete

Placing

In

Placing

the

concrete,

the

block construction

system was employed

and contraction

joints

were

provided

every

15m

transversally

and

30m

longitudinally.

.

Both precooling

and pipe

cooling

systems

were

employed

in order

to control

the

temperature

of

dam.

Conqet

after

the

second-stage

pipecooling,

both the

transvelse

and thi longitudinal

joints

were grouted.

The

concrete

used was

a moderate

heat

cement

with anlir

entraining

agentffor

the

fine aggregate

a

mixture

of river

sand

and

crushed'stone

and

for coarse

aggregate

crushed

stone to th€

maximum

size of

l50mm.

The unit

cement

content

from

the surfac€

to

the depth

of 3m was

2,lokg,

while

it was

reduced ro

180

and 165kg

on

th" it-",

p"i

oi,rr" au-.

(5)

Measuring

of the

dam

In

order

to

maintain

safety

of the

dam,

the dam

is equipped

with

various

measuring

instruments,

of which

the

principal

items

are

as follows

:

1)

For

measuring

the interlal

temperature

;

2g7

thermometers

at

1g5

spots

2)

For

measuring

the

strains

and

stresses

;

2g4

strain-meters

and 29

suess_merers

3) For

measuring

the

opening

of

joints

;

77

joinr

meters

4)

For

measuring

the deflections

;

Pendulum

line

measurement

at 2 srrots,

alignment

survey

at 2

spots

and

precise

trian-

gulation

at 5

spots

5)

For

measuring

the

uplift pressure

;25

spots

6)

Measurement

of leakase

7),-

Measurem^ent

of eanhquake

;

13 displacement

mete$

and 5 accelemtion

seismographs

-

lt has

been-26

years

sinc€

ogochi Dam

was

constructed

in 1957.

As

a t".utt

of tlhe

observation

based

on these

appar-

atus,

no

unusual phenomenons

are

detected

in the

dam.

(6)

Settlement

of both

banks

ogouchi

Dam

has

been

measured

periodically

the

settlement

of

As

the

result

indicates

in Fig.

L,

the

settlement

has

the

equal

banks

can

be

judged

to

be

stable.

for

about

five

years

because

of

the

concrete

placing

was

finished

and

in

the grouting

surface

at

both

banks

by

precise

levelling.

tendency

at

the

every

measuring

date.

And

so

boih

\

5OOm

R ising

Sett

lemenf

Grophicol

oresentotion

ot resulls

Fig. I

Settlembnt of

ground

surface

Woter

level

ond Storoge

ot eoch

meosuring

Time

Dole

Woler

level

Remorks

r957

5-8

EL

UM

Oolum

6

1969 ll

-12

526

22

t97 |

t2

.

518.98

197

7

tO

524

02

I

?9

6 5

o 51

55

F

m

-/

\

4

S

74

-3Omm

24.

OKT]RA

DAM

Location

Nearest

City

.

River

Purpose

Catchment

area

Mean

annual

discharge

Years

of

construction

.

Type

FounCation

Height

Crest

length

Volume

Spillway

TyPe

........

.........

..... controlled

Type

and number

of

gate

....................-.

Crest fixed roller

sateX4

Maximum

discharge

capacity

.... -............

1,425m7s

Reservoir

Gross

capacity

..........

2g

x

10tnl

Effective

capacity

...... 25

x

101n3

Area..................

.....

1.7km,

Drawdown

range

.......

30m

Owner

,...............

...........

Ministry

of Construction

Engineering

by

...............

Ditto

Construction

by

.....................

Maeda

Construction

Co.. Ltd.

- .

Okrra

Dam

is a

multi-purpose

dam in

the 6kura

river constructed

by Ministry

of

constuuction.

The

foundation

rock

of the

dam

consists

of tuff

and dykes

of

andesite

in Tertiary,

and

comprises

an upper

wide

t"ir"v

*iirr

a flit

hilly land and

a

::l1t-::t1""*.J-*"Ped

valley

al.

the_

bottom .

The uppei valley

is ;bout

300m^wide

ano

+0rn

high

"uou"

t

"

hilly land

at

Ine

crest

ot

the

dam,

on the

other

hand

the lower valley

is

only

zl0m

wide

and 40m

high.

Un-der the

coodition

of this

toPography,

a multiple

arch dam

which

is uncommon

in Japan was

constructed.

N

SR

-;:-\

Miyagi-cho,

Miyagi-gun,

Miyagi-ken

Sendai-shi

Okura

Flood

control,

Irrigation,

water

supply

and

Hydroelectric

89km'

4.7m3ls

1958-1961

Multiple

arch

Tuff

and Andesite

82m

323m

226.000m3

B

tl,'Ol

tx

c

.6/

\rt

r \9

o

to 20 30

40

50m

GENERAL PLAN

75

Japanese National Committee on Large Dams. Dams in Japan, No. 10

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