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

EL

280

m

HWL=

260

240

220

200

wL 24065

Apron

EL I94

Dom

o

to

20

30

40

50m

TYPICAL

CROSS.SECTION

76

HRF!..."

UPPER

STREAM

VIEW

)

25.

OKT]TADAMI

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

Hinoemata-mura,

Minamiaizu-gun,

Fukushima-ken

Aizu wakamatsu-shi

Tadami

Hydroelectric

426km'?

41.8m'/s

1954-t961

Gravity

Gabbro

and

Siltstone

157m

480m

1,636,300m'

Controlled

Crest

radial

gateX2

2,000m'/s

601

X

10tn3

458

X

101n3

1L.5km'?

60m

Electric

Power

Development

Co.,

Ltd.

Ditto

Kajima

Corporation

-

.__z_____>

PLAN

^8

O

5Om

l,r.,l

77

1. Introduction

Okutadami

Dam was

constructed approximately

230km upstream of the

estuary of the

Tadami

River of the Agano

River

System which

drains

into the

Sea of Japan in Niigata ken. This

locality is in one

of the

heaviest

snowfall regions of

Japan

with

annual

snowfall

of about 20m and

annual average

precipitation

of about 2700mm.

Hydroelectric

dams;titizing

the

abundant

snowmelt

water

have been

constructed on the river in cascade

to the downstream

stretches.

and throush

effective

utilization

of heads;

one of the

greatest

power

source areas of the

country is constituted.

Okutadami Dam

is the

most

upstream

of

the dam group,

and together

with Tagokura Dam

(concrete

gravity

type,

crest

length 462m.

height 145m)

approximately

30km

downstream,

regulates

the flow condition of the Tadami

River. Okutadami,

hai a

maximum outout of

360MW,

annual

energy

production

of 524

Gwh, downstream benefit 318cwh,

and is one

of most

Drominenr

of the laree

dams

in

Jnpan.

2.

Topography

and

Geology

^

The damsite

comprises

a

steep V-shaped valley,

but from mid-height of the

slopes both

banks

become slightly

gentle.

Overburden

is

thin

and their distribution

is limited

at mid-heieht and above

at both banks.

The foundation

rock

of the damsite

is mainly

composed of

gabbro,

the

greater

part

of which

is cataclastic.

The catac-

lastic

gabbro

is brecciated

with

a low degree

of cementation, whil€ ordinary gabbro

is

cracky but

hard.

Siltstone

distributes

at the

right bank from

the vicinity of the dam axis to

the upstream

parr.

while

metagabbro

and ser-

pentine

are distributed

downstream

of the dam axis

and

within

the dam bed, with

slate locally

existing

surrounded by the

above.

The

siltstone

is

weak against weathering

and erosion, and

generally

is readily

softened.

CIay seams are well-

developed

in

the serPentine,

while

the metagabbro

has much cracks with

some of them

accompanied

by

clay seams. The

slate is

brecciated.

has numerous

cracks,

and is brittle

and easily broken into small fragments.

- _The

river

bed

consists

of gabbro

cataclastic

in

part,

but the degree

of cementation is

high.

Weathering

is prominent in

the

left-bank

cataclastic gabbro

and the

zone

of

poor

rock

at

the

ght

bank.

The siltstone

is weathered

and

relativelv soft.

78

3.

3-1

Construction

Materials

Since a

suitable

deposit

of sand-gravel

for concrete aggregate

was

not available

in

the vicinity

of the damsite,

the

apProximately

3,500,000m3

of aggregate

required were

quarried

by the bench-cut

method

in

grunolio.it"

at the

euarry

approximately

5km lpstream

of the

dam.

Cement and fly ash were

transported

by rail

to Koide

about

32km

from thi

dam'

with

the

section between Koide

and the

dam hauled by truck,

but since

traffic would

not

be

possible

with

the existing

prefectural

road in

the wintertime

because

of snowdrifts,

an access

toad of total

length

of approiimately

22km

(of

whici

18km

were

tunnels)

were

newly constructed.

3-2.

Concreteplacement

__ -Concrete

was

placed

by a 20t

arc-movement

cable crane using

6mr or

3m3 buckets,

with

a batching plant

of four mixers

(3mr).

Placing

of conqete was

started

in September

1958 by the block

method with

even-number.

d;;nstreamside

blocks

placed

first, while

after

switching to

layer

placement,

lifts of 1.5m were

used leaving

central

Block

to the end,

completion

being

in

September

1961.

The maximum

daily

and monthly

placement

quantities

were

3,?00m' and

102,000m,,

respcctively.

The minimum

unit cement was

140ks/m3.

3-3.

Contruction

Joints

The

stardard

for transverse

joint

spacings was

18m. For longitudinal

joints,

sinc€

the maximum

width

of the bottom

w_as

-as

much

as 120m,

spacings

of 37.5m were

taken as the standard

with

placement

done

by the

block method

up to

EL.

668.0m

abole

which

concete was

Placed

in layen.

Joint

keys

were provided

as

a rule,

but at places

where

foundation

rock

was_

of_

poor

quality

and at

penstock

btocks

joint

keys

were

not

provided,

allowing

blocks to

move fteely

and not be

affected

by

blocks

on either side.

3-4

Cooling

Pipe

cooling

was

cement.

Primary

cooling

Winter

Summer

Secondary

cooling

Winter

Summer

performed

according

to the following

in

order

to

prevent

cracking

due

to

heat of

hydration

of

River

water

Chilled

water,

6-10"C

River

water

Chilled

water.

2-4'C

3-5.

Foundation

treatment

. .

The

depth

of curtain

grouting

was

one third

of the dam height

vdth

grouting

pressure

approximately

three times

the

nyorostanc

pressure

as standard, and

the total

length of

grouting

was

approximately

52,(m0m.

consolidation

grouting

was performed

over

the entire foundatiorr

of the

dam with

staggered

holes

at 6m spacing

and

standard-depth

of

10m. Grouting pressures

was 2 ro skgflcm'z;

and the

total length

was appi;ximately

57,000m.

At the

right

bank

of the damsite

there was

scrpentine crossing

the dam

axis in

the upitrcamdownstream

dircction and

scattered

siltstone

as lYell,

and these

rocks were

judged

to be unsuitable

for

the dam foundation.

Therfore.

the

sementine

was

replaced

with

concrete and the poor

rock

remaining at the

intermediate part

treated

with

grout.

In

effect, stresses

from

the

dam

were

to be

transmitted

to hard

slate of the basement while

stresses would

not be transmitted

to Door rock.

4.

Power

Generating

Facilities

The

outline

of

generating

facilities

is

the following.

The avaitable discharge

of

249m'Aec

is drawn

by an

intake struc-

ture (3

caterpillar gates

of width

of 6.5m

by height

of 5.7m). The water

taken in,

on

passing

through

thiee

penstock

lines

of inside

diameters

4.3m'3.8m

and lenghts

approximately

190m, is used

at an underground

fr*ethoirse

of

width

of

22.4m,

length

of-89-.6m

and

hcight of 3?.8m

built immendiately

downstream

of the

dam.

U-tilizing

an effective

head

of 170m three

vertical-shaft

Francis

turbines and generators,

have a maximum installed

capacity

of

360 MW.

79

760m

NW

740

20

7CO

680

360

540

i20

ioo

TYPICAL

CROSS SECTION

760m

740

TN

-m

80

TIPSTREAM

VIEW

| /

(62.rm)

l8.o'12.O,?4.O.

9(or80=

o2040m

80

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

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

Crest radiai

gateX5

Maximum

discharge

capaciry

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

2,3000m%

Reservoir

Gross

capacity

..........

22.8x 10tn,

Effective

capacity

...... 26.7X 10tn3

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

..... 1.07Kmr

Drawdown

range .......................,.........

4?.0m

Owner

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

...........

Ministry

of Agriculture,

Foreshy and

Fisheries

Engineering

by

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

Ditto

Construction

by

Taisei Corporation

The

Osako

dam

is located io

the

upper

reaches of

the Kinokawa

River

flo'wing

through

both

Nara

and

wakayama

prefectures.

The

dam

site is in steep

mountainous

area, and the

watershed

of

the eait

i, fotit"o

ly Ivtt.

-Ooaigatrara

wtrich

:1-Tlill"*"

as

a district

with

healy rain

in

Japan. Therefore

a considerably

large

vatve

was

taken

fo! the

design flood

olscnarse.

f]hi geotogy

of

the foundation

consists

of alternation

of slates,

cherts

and

sandstones

which partially

sandwich limes-

tones

of

small

extent.

As

the fouudation

has adequate

bearing

capacity,

an

arch dam

is selected

though

ihe valley

is

com-

paratively

wide.

At

higher

elevation

to

design

the

favourable

The

top

of

the

left

slopes.

To protect

the

scale.

In grouting

much

PLA

N

-

,t

26.

OSAKO

DAM

Ku*uluri-mura,

Yoshino-gun,

Nara-ken

Kashiwara-shi

Kinokawa

Irrigation

115Km'z

7.6m3ls

1963-1973

Arch

Alternation

of

States,

Sand stone

and

Cherts

70.5m

222m

158.000m3

of the

right

abutment,

the

rocks

are weakened

by

fracturing.

Many

structural

analyses

were

made

domed

arch

in consideration

of

reducing

the

thrust

force

against

that

abutment

for

safety.

bank

is

covered

with

terrace

deposit,

and

the

weathered

rocks

are

distributed

on

the

reservoir

slopes

against

failure,

pneumatically

applied

concrete

and

rock

bolts

were

executed

on a larse

attention

was

paid

to

the treatment

of the calcareous

limestone.

86

t

,*'

5

$

i

81

#

4r

,1t

I

400fr

R

6l

I

e

r-:sgqo

TYPICAL

CROSS SECTION

82

UPSTREAM

VIEW

EL

460

Righl

Bonk

450

440

\

430

t7

EL

4r8

982

Lefl Bonk

NO

I EL

339

241

EL 460

450

444

,- 410

420

4O

400

33C

380

37C

360

350

340

dom bose

EL 35O

OOm

33O

320

\

!{o6

EL

35ZO0O

31q kt,

340

(a

330

,

,32q

lypicot

?ecto?icol

profites

.Ad

lolus

'-r

rrver

depoSrfs

-

I sloie

IuI! siliceous

stole

_-l sondstone

:-:

sondstone

lnd

sondy stote

:r^

cOngtom€fottC

Sqndslme

ond

cmgtorerolic

sondy

sEle

il-II) cns?

::m

sholstein

= lime

stone

:L 4@

450

440

430

4n

4to

:tOO

380

370

56U

340

320

rock

ctoss

_l-lo

zorue

]

CL

ZONE

-

-lO,rzortre

_____l

cHzoNE

l

B

ZoNE

-

foutl

md

frc:ture

zone

-- -

- --boundory

ol

s?rotum

oJ__ry_4o5o'

Fig. 1

Geological

formation

at the site

of

the dam

orl2-l9..#9jo.

Fig. 2 Lugeon

Values

Right Bonk

Lefl

Bonk

o.r|||JP-jltclq-l9.go.

Fig.

3

Grout Take

(kg/m)

Lcfl

Bonk

ihrusl block

8-J

e-a 8-l

!ro

!80

t70

!€o

Righl Bonk

wino dlm

a-r5- !-r

B-13

B-la €-ro

8-9,4-6

e-7

B-6 6-5 B-a

L..@.9

F

s

370

:tao

:!60

vto

330

s

5ro

5)

2S

_JSo

210

26

I cnehd

gg

-

foufido?tnol

hole

-.--

check

hole

-----

supplernenlol

hole

o

lc

20 3040 50m

r

2

!rlo

glo

tlo

300

2SO

zfo

260

2 EL354

37Q

NO IO

EL 332 4

Development

of

upstream

Fig.

4 Results

of curtain

grouting

R?

27.

SAKUMA

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

.

Crest

roller

gateX5

Maximum

discharge

capacity

10,000m3/s

Reservoir

Gross

capacity

Effective

capacity

Area

Drawdown

range

Owner

Engineering

by

Construction

by

Sakuma-cho,

Iwata-gun,

Tenryu-shi

Tenryu

Hydroelectric

3,827km'

158m3/s

1953-1956

Gravity

Granite

155.5m

293.5m

1,120,000m3

Shizuoka-ken

326xL0tn'

205

X

LOum'

7.2km2

40m

Electric

Power

Development

Co.,

Ltd.

Ditto

Hazama-Gumi.

Ltd.

,a

{L:

b

;,

#

I

R4

---,/,

':7/

PLAN

il

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

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