Japanese National Committee on Large Dams. Dams in Japan, No. 10
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The spillway
consists of four radial
gates,
9.0
mete$
wide
and 8.4
meters high each, and is
capable
of discharging
2,160
rnt/second of water that is 20
percent
over the maximum
design discharge of return
period
of 100
years,
1,800 mr/
second.
The
final decision
on the type
of spillway was made after other
alternatives
were
studied in detail
;
namely, a free overflow
spillway located
in the c€nter of the arch, and a tunnel
spillway
though the left abutment, however for safety, economic
and other reasons
ski-jump type spillway
was applied as final
solution. As for the safety of this type of spillway, caretul
and comprehensive
studies such as extensive hydraulic
model studies,
etc., were undertaken at the Electric Power Central
Research
Laboratory,
Tokyo
and a satisfactory result
was
proved
by an experimental
discharge
after the initial
filling of the
reservou.
Maior problems
during the construction works
were the
procurement
of
aggregate and material transpoftation.
Since there was
no natuml aggregate available
near the dam site,
both coa$e and fine aggregate were manufactured.
Therefore
a 240 ton/hour dushing
plant
was installed
at dam site.
Moderate heat cement approximately 90,000 tons
was
used for
the dam
construction and
the cement was transported
by means of
cable way, 57.5 kilometers long
Concrete
was
placed
in the dam which was
divided into blocks
of 20 mete$
wide
and 2 meters high.
Construction plant,
a
180 mThour batching and mixing
plant
and
two 13.5 ton cable cranes were used for
placing
a
total of
390,000 cubic
mete$ of concrete in the
period
from
October
1953 to June 1955, and
the
maximum rate of
concrete
placing
reached
up to 39,000
cubic
mete$
pe!
month.
Pre-cooling
and
pipe-cooling
were employed and the tcmperature
of concrete
was reduced 6 to 7'C.
For these
cooling
purposes,
a 30 ton/day ice
plant,
d
18 ton/hour cooling water
plant
and two 15 toD,/day cooling
water
plants
$,ere
used.
Cracks
were
not
found
in any block
where
concrete was
placed
at 3 day interval. Contraction
joints
were
grouted
with
a
pressurc
of
4.2k9lcm?
or less
at first and after
moling down the conqete temperature of
dam body
re-
grouted
with
lokg/cm:
or less during the
period
from February
to March, 1956.
The foundation
treatment consisted of consolidation
grouting through
7,900
meters
of drill holes, cu
ain
grouting
-
5,700
meters, rim
grouting
-
2,100 mele$ and contact
grouting
-
3,300 square meters of contact
surfaces.
36
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N\ii'
o?5en
TYPICAL
CROSS SECTION
il-zlgm)
450
400
SPILLWAY
CROSS
SECTION
(RIGHT)
:L5GM)
450
400
350
O?55Om
4
PLAN
UPSTREAM
VIEW
37
11.
KAIryAJI
DAM
Location
Nearest
City .
River
Purpose
Catchment
area
Mean
annual discharge
Years
of construction
.
Type
Foundation
Height
Crest length
Volume
Spillway
Type
Type and
number
of
gate
.
Maximum
discharge capacity
Reservoir
Gross capacity
Effective
capacity
Area
Drawdown
range
Owner
Engineering
by
Construction
by
Fujiwara-machi,
Shioya-gun,
Tochigi-ken
Imaichi-shi
Kinu
Flood
control,
Maintenance
of
normal function
of the
tion and
Water supply
324kmz
2.8m'/s
1974-1,981
Arch
Diorite
and
Tuff breccia
140m
320m
656,000m3
Controlled
Crest
fixhd
roller
gateX6 and
Conduit
roller
gateXZ
4.400m3/s
83.0X
L0um3
76.0x
L0um3
2.Zkm'
72m
Ministry
of Construction
Ditto
Kajima
Corp.
river water,
Irriga-
*
38
GENERAL
PLAN
or-----T----5o^
TYPICAL CROSS
SECTION
I
I
Curtoin
Grouting
39
(1)
Topography and
geology
of
the site
Kawaji
Dam is locared
on the steep
valley of the
Kinu River.
The dam sit€ forms a steep cliff
affected by faults and
joints
parallel
to the river.
The left bank
mostly consists
of diorite
and the right
bank mostly consists of tuff breccia.
TtIe
foundation
rock is fresh and
hard in
general.
However vertical
faults
parallel to the ver exist
on both
sides of the
river, which affect the stability
of the dam be-
cause of their direction.
(2)
Design
of the dam
The location of the
dam axis
was restricted
within 100m of
the dam site
along the river because of th€ topographical
condition of
the valley.
The
plan
of the arch dam
is so desig(ed
as to direct
arch
thrust
into the deep
part
of the foundation
rock
in considera-
tion of the safety factor
for sliding
along the faults.
Therefore
small
central angle of arch of 75' is adopted.
Tensile
stress
of arch at the crown of the
downstream
face is eliminated
by using
parabolic arch.
Nafow
part
of the
valley at the bottom
was
plugged by concrete
to secure
the appropriate shape of
arch and at the
top of the right abutment the thrust
block is constructed
to
transmit
arch
thrust to sound rock.
(3)
Construction of the
dam
The dam
was
divided into
24 blocks
of 15m
width and constructed
in 2m lifts. Modemte
heat cement was used
to re-
duce temperature rise which
was iontrolled
by embedded
coils.
Agglegate
was also
precooled
in summer.
Concrete was
placed
in
4
yea$,
each
layer being
about 50cm
thick.
The upper
layer was
placed
over the lower
layer
within two houn. Curing
of conqete
was
performed
by
filling
water to
Prevent
surface from drying, and
in winter three
layers of curing mats
(t:10mm)
were laid to
prevent surface
from
freezing.
(4)
Foundationtreatment
Consolidation and curtain
groutings were caried
out
to improve
the
property
of the foundation rock. Depth
a
drill
hole of curtain
grouting
is the
l;ngth
which is equal
to the
maximum
height of dam
at the river bed or two-third
of it
at the
top of abutments. Grouting
was cauied
out by split
spacing
method.
Prestressing of the foundation
rock
of both
abutments
was carried out
to reinforce
prevailing
faults
parallel
to the
river. Total length of the PS
cable
was 10,000m for
200 holes
and
total forc€ of
prestiessing
was
48,000 ton.
UPSTREAM
VIEW
,At-
40
T2.
KAIryAMATA
DAM
Location
Nearest
City .
River
Purpose
Catchment
area
Mean
annual
discharge
Years
of construction
.
Type
Foundation
Height
Crest
length
Volume
Spillway
Type
Type
and
number
of
gate
Maximum
discharge
capacity
Reservoir
Gross
capacity
Effective
capacity
Area
Drawdown
range
Owner
Engineering
by
Construction
bv
1. Topography
and
geology of the site
Kawamata Dam is located
on the very narrow
and steep U-shaped
valley of the Kinu
River. The spar of the
valley at
the site is 110m compared
with the height of the dam
of 120m
ard it is a suitable site
to coDstruct an arch dam.
The
foundation rock
of the site mrlsists
of rhyolitic
welded
tuff. It is
very
hard but
there eists many faults,
seams
and
joints
in it.
2. Design of the dam
An arch dam was adopted
for Kawamata
Dam from
the
topographical and
geological points
of view.
It is desirable
that cent'ral angle of arch is 110"
to 120' for the stress
distribution
of
the dam but in the design of Kawamata
Dam,
central
angle of arch was designed
in consideration of
the stability
of the
foundation rock for sliding
because of
the
prominent
faults,
seams and
joints.
After the elaborate
study on
the stability
of the foundation
rock,
contral
angle of 60'to
70"
was
(//
I
PLAN
OF
KAWAMATA OAM ANO ITS
VICINITY
,;
(
Kuriyama-mura,
Shioya-gun,
Tochigi-ken
Imaichi-shi
Kinu
Flood
control, Maintenance of
normal function
of the river
water and
Hydroelectric
179km'
9.5m3/s
1957-1965
Arch
Liparite and
Welded tuff
1,17m
131m
1.67,500m3
Controlled
Crest
fixed
roller gate
X
6
and
Conduit fixed
roller
gateX2
1,350m3/s
87.6x
106m3
73.7x106m3
2.6km'
46m
Ministry
of Construction
Ditto
Kajima
Corp.
\
t
Ni
G
PLAN
4T
considered
the most desimble
for
the foundation,
because
the
arch thrust
directed
into
the deep
Pafs
of
the foundation'
But
in
such a case, it
was difficult
to eliminate
tensile
stress
of
the arch
dam.
So central
angle of 80"
to 100'was
finally
adopted. It was much smallgr
than
those
of the
other arch
dams
in those
days'
The
dam was designed
in a symmetric
arch
dam using
a
saddle
to ensure
the
approPdate shape
of the
dam'
3. Foundationtreatments
a)
Tnnsmiting wall
There existei
many seams
and
joints
having
angle
of 40'
to 50"
to the
arch thrust
in the left
abutment.
Therefore
a
transmiting
wall l\,as co;structed
in tie
foundati6n
rock to
prevent sliding
of the
rock
and transmit
the thrust
into
the deep
part
of th; foundation
rock.
The
dimensions
of
the
wall
was 70m
high and
40m
long in depth.
The foundation
rock
di-
uid"d into two
parts by the transmitting
wall
was tied
by
the
prestressed
tie rods described
bellow'
b) Prestressing
of the
foundation
rock
prestressing
6f the foundation
rock
was carried
out
to
unify
the devided
rock
by the tnnsmitting
wall and
existing
faults and
joints.
Prestressing
was applied by
DYWIDAG
method.
BBRV
Method
and
wile lope
method. Applied
force
was 15800
ron
or 5
toD/m+y DYWIDAG'Method,
8400
ton
or 3.5
ton/m'?by
BBRV
Method
in the left abutment
and
5400 ton or
4 3
ton/m: by
wire
rope
method
in the right
abutment.
c) Foundation
grouting
Consolidationiroutirig
and curtain
grouting were
carried
out
elaborately
including
the shoulder
rock of
the dam'
TYPICAL
CROSS
SECTION
UPSTREAM
VIEW
c,
970
960
950
940
930
920
910
soo
490
8ao
870
460
A'
+L
13.
KUROBtr
DAM
Location
Nearest
City
.
River
Purpose
Catchment
area
Mean
annual
discharge
Years
of construction
.
Type
Foundation
Height
Crest
length
Volume
Spillway
Type
Type
and
number
of
gate
Maximum
discharge
capacity
Reservoir
Gross
capacity
Effective
capacity
Area
Drawdown
range
Owner
Engineering
by
Construction
bv
1.
Introduction
The
Kurobe River
originates from Mt.
Washibadake,
in the Kita Alps Mountains,
and after
merging a number of tri-
butaries,
it
flows down
86km to the Sea of
Japan.
The river basin is one of the
greatest
hydro
power
source of Japan
be-
cause
of heavy
snorfall and rainfall
with an annual average
precipitation
of about
3,800mm. The development on the
Kurobe
River
System was started
as early as in 1920's and
now 15
hydropower
plants
with
total
g€nerating
capacity of ab-
out
790 MW were
constructed over
the
past
60
years, Kurobe Dam is located
on the uppermost
on this river system and
improves
the
flow conditions of the Kurobe
River
year
round.
The undergound power plant
has
a maximum installed
capacity of 335 MW.
Kurobe Dam
project
is truly of
great
significance
in the history of dam construction
as the most advanced and highest
arch
type dam
in Japan constructed in spite
of immeasurable
hardships.
Kurobe
Dam is located in the Chubu
Sangaku
National Park and now becomes a
major
part
of the Tateyama-Kurobe
Alpine round-trip
course with about one
million
visitors a
year.
During the tourist season
Kurobe Dam discharges
water
and it creates
a magnifrcent scenery.
"El,:i:*
o
prcs40s
Tateyama-cho, Nakaniikawa-gun,
Toyama-ken
Omachi-shi
Kurobe
Hydroelectric
184.5km'?
16.2m31s
1958-1963
Arch
Biotite
granite
186m
492m
1,580,000m,
Uncontrolled
1,260m'/s
199.3X
106m3
148.8
X
106m3
3.5km'?
60m
Kansai Electric Power
Co.,
Inc.
Ditto
Hazama-Gumi,
Ltd.
/r
Ev
;
$5)
9 \
i;
;$
+s,
ft
Fi
);
I
o/
tr
\\
PLAN
43
TYPICAL
CROSS SECTION
2.
Topography
and Geology
The
dam is situated in the
Kurobe
Gorge between Mt. Tateyama
and Mt.
Ushiro-Tateyama
of the
Kita Alps
Mountains.
The right
bank is steep to a high
elevation, while the left bank is not
so steep up
to EL.
1400m and becomes
precipitous
above
EL. 1400m. Overburden
is
generally
thin on the right bank
and 50
{0m thickness
up to EL. 1400m on
the
left
bank. As
there are dales downstream
of the both abutments, the ddge
of the abutments
are
relatively thin toward
thrust
lines
of the dam.
Howevet, on the upstream of the
present
site, the
valley
width
is much wider
and the overburden
on
the left
bank is
thicker. And so the dam
site
was
selected
The
dam foundation
is composed mostly
of biolite
granite which
contains biotite weathered
or chloritized and
is
gener-
ally
semi-hard.
The
granite
is pa
ly aplitic and fairly hard in lithology,
but
is partly
greisenized
and
soft.
In-situ
rock tests $rere
conducted by using a unprecedent large
scale test block of 10mr to
ensure the
non-uniformily of
the
rock.
Such test blocks of 25
pieces
were
used for block shear test, rock shear test
and fault
shear test, and as well as
for tdaxial
compression
tests of the rock and the
fault
breccia. The in-situ
tests also involved
seismic
prospecting
tests,
iack
tests and water
chamber tests. Laboratory
rock tests
were also
conducted with smaller
test
pieces.
These
in-site
rock tests of Kurobe Dam
took the initiative
in the field
of rock mechanics
in the world, and
greatly
con-
tributed
to
the study
of the actual behavior of rock mass.
Model tests
were conducted with a 1/90-scale
model
to study the static behavior,
and with a
1/180-scale model to study
the
dynamic
behavior.
Smaller
model
tests of over 40
pieces
were
also conducted with
a 1/500-scale model
for the static
tests
of several types
of the dam with different
shapes
and rupture tests.
Other
laboratory tests included
photoelastic
tests to study
the
behavior of the foundation
rock and to determine the
methods
of the foundation treatment.
4. Design
A dome
in the
centml
portion
of the dam is designed as
a double orvature
arch on the basis
of the
"inclined
arch"
concept.
The inclined
arch was adopted from
the
reason that the foundation rock mass at upper
elevations on both banks is in-
adequate
to
support a large scale dam in view of deformability and strength, and besides the ridges
of the abutments are thin.
Gravity type wing
dam,
with
the axis line almost
perpendicular
to dome axis, was constructed
on both abutments over EL.
1390n.
The
ioint
of the wing dam and the dome is
provided with open slots so that both structures
may behave independently.
5.
Construction
The
excavation
of foundation
rocks,
in total amounting
about 1.3x1ffm3,
was
started from
August,
1958.
Placcement
of mncrete in 3m lift began from September,
1959. The maximum size of aggregates is 180mm.
Compacting
the concrete was done by bulldozers equipped
with
six
vibrators. The
maximum
placement
rate reached as
much
as 147,000m3
a month in August, 1960, and this marked
th€ world record.
The foundation
tTeatment
for
the
fractured
and
other soft zones involved consolidation
grouting
work and replacement of
soft bedrock with
concrete, which amounted to 48,000nf
on the left abutment and 11,000m'on
the
right abutment.
A huge
curtain
grouting
was
pedormed
in the upstream
of the both abutments in order to
prevent
seepage
through the
bedrock.
The
total length of the curtain is 110,000m
and the total
quantity
of
cement
used for the
grouting
amounted
to
16,000t.
6. Filling of
the reservoir
Filling began ftom
October,
1960, about one
year
after
the start of concrete
placing
and
power generation was partially
started from
January, 1961. The.height of the dam
for this intermediate filling
was
120 meters.
The water level
had been
gradually
elevated since then at a
rate of L0-15 mete$ a
year
and reached the normal watet level
in 1969,
ten
years
after the start of water filling and six
years
after the completion
of the dam. The
purpose
of the filling over
such a long
time was to minimize the deformation of
the foundation
rock and to adapt itself
gradually
to the changing load
conditions.
o o20r4050
lllll
UPSTREAM
VIEW
45