Indian National Committee on Large Dams. Design and Construction Features of Selected Dams in India
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FIGURE
25
: Photograph
showing
the
view
of
cooling
plant.
n
order
that
there
might
;e of
aggregate
at any
time,
on
provided
for.
This was
e
crushers
each
of which
had
'hese
were
fed
by
762
mm
Nos.
28,29,30,
31
and
32.
in.)
cobbles
and
76.20 mm
)
'standard
head' medium
ed.
This
crusher
had
an
tonnes (175
tons)
per
hour.
4 in.)
'pea'
gravel
rock
to
m
(5$
ft)
'short
head'
fine
out-turn
of 137.17
tonnes
(l,35.tons)-per
hour
was
used. The
1.22
m
1a
f0
'short
head'
fine
bowl
cone
crusher
had l0r.6l
tonnes
(100
tons)
P.I
hour
capacity
for crushin_s
38.10
rnm
(16
ln.,
rocK
rnto
'pea'
gravel.
These
cone crushers
operated
in
a close
circuit
with
the
screenin_e
plant
by.dischar-qing
the
crushed
material
back iito
the
marn
surqg
piJe
through
762
mm
(30
in.),
rvide
belt
conveyor
No.
33.
54
All
equipment was
electrically
operated
and
had
FIGURE
26
: Photograph
showing
the
view
of
batching
and mixing
plant
stage
I.
modern push-button
remote
controls
which
interlocked
3.8
Aggregate
Cooling
As
already
described,
it
had been
decided
to
precool
the
aggregate
so
that
placing
temperature
of
set-up.
It was
decided
to choose
the'immersion
method'
of
cooling
based on
principles
of
refrigeration.
An
elaborare-'cooling
plant'
(Figure
25) was
set up
at
Bhakra
for
chillin,e
of
aggregates
and
-consisted
of
the
following
components
:l
(l)
Refrigeration
planr
for
chilled water
supply.
(2)
Coolin,s
tanks for
chilling
of aggregates.
(3)
Dewatering
screens.
(4)
Transportation
of ag_uregate
:
(i)
processing
plant
to cooling
plant,
(ri)
within
the
cooling
plant,
and
(iif)
cooling
plant
to
batching and
mixing
plant.
The
cooling
plant
was
located
on the right bank at
the
elevation
426.72 m
(1,400
ft).
The
framework
was
of steel column and
beam consffuction supported
55
FIGURE
27
:
Photograph
sbowing
the
vierv
of the
second
stage
of
batching
and
nixing plant.
56
3.9
Batching
and
Mixing
plant
About
4.2
million
cu
m
crgte
were
to
be
placed
in
t
mixing
plant
(Figure
26)
h,
structure,
consisted
of
four
a
bin
of
six
compartments
v
1269.8
tonnes (t;250
tons)
a
top.for
spilling
the.classified
aggregate
into
the com-
partmenr
of
the
bin
reserued-foi
that
ri"r
*o
auto-
matic
.
weight
batchers.
Equipped
for
--
"uto-uti,
operation,
the plant
had
ul
^tne
-od.ro.
G"tures
required
for
close
control
of
weighiog
uoo-*ixing.
one
m.an
op€rated
the
mixing
p-lant
from
ihe
control-"poinr
The
mixing
time
alloied
*u,
Zg
-lnut.,
anO
the
Tllrmum,capacity
of
the
plant
was 244.36
cu
m
(rlu
cu
yd)
per
hour.
Tltq
p]unt
was
located
on
rhe
right
bank
at
EL
414-53
m
(1,360
ft)
for
the
first
stage"of
"otrcteting.
FIGURE
28:
Photograph
showing
the
view
of
the installatibn
of first
stage
(steeltresfle
by
American
revolving
crane).
For
the
second
stage
it
was
re-erected
at
El.
481.59
m
(1,580
ft)
(Figure
27).
3.10
Concrete
Placed
from
Steel Trestles
Concrete
was placed
in
the
dam
by cranes working
on
steel
trestles.
The first
stage
envisaged
construc-
tion
of
the
dam
up
to El.
4l4.Sf m
(t,360-ft),
involving
placing
of
2,293,748
cu m
(3,000,00Ocu
yd)
6f concrete.
Three
trestles
aligned
parallel
to
the dam
axis
were
erected
(Figures
28
and
2g\.
Trestle
No.
I with its
top at
El.
369.42
m
(l,ZlZ
ft)
covered
the dam up-
stream
of
the
axis
and
the upstream
of claystone,
which
was
to be
excavated
and
bickfilted
with
concrete.
Trestle
Nos.
2
and 3, rvith
their
tops
at
El.
414.53
m
(1,360
ft)
were
used
for
placing
the concrete
in
the
main
dam.
Trestle
No.
4
with
its top
at the
EI.
344.43 m (1,130
ft)
had
been
erected ai
right
angles
to
the axis
of
the dam
for
the
placing
of concrete in
the
spillway
apron;
and
training
walls
(Figure
29).
Trestle
No.
5, actually
a continuation
of Trestle
No.
2"
was
erected with
its
top
at
El.
481.59
(1,590
ft) for
concreting
during
the
second
stage
(Figure
30):
A
sixth
trestle was
required
for
concreiingtthe
left power
house.
Seventh
trestle was
erected for
the right
irower
house
later
on.
Testles
consisted
of standard
spans of 19.51
m and
2!.08
.
(q4
ft
and
79
tt) supported
on
towers respec-
tively
10.97 m
x
13.41
m
(36
ft
x 44 ft)
and 13.11 fu x
!?.!l
m
(43
{tx44
ft). Some
toweis were
as
high
as
91.54
m
(320
ft) which
was
believed to
be
a record for
this type
of
structure.
The
trestles
were
decked with
timber
and carried
two
standard
gauge
tracks with
necessary
crossovers
for concrete
transfer cars,
and
crane rails were
13.41
m
(44
ft)
apart.
Four revolving
cranes of
ll,79l
kg
(26,000
lb)
capacity at 45.72 m
(150
ft)
radius
and two double-cantilever cranes
of
97.54
m
(320
ft)
span
and I1,791kg
(26,000
lb)
capa-
city
had
been
purchased
for
working
on
the trestles.
*^_ry#
57
FrGUR-E
29:
Photograph
showing
the
placement
of concrete
from
trestles
in
stage
I
(also
shorving
block
systen).
I*ojjt^_mee
d9r1icfl,
of
1.t,337
kg
(25,000
Ib)
capaciry
at
59.3?
m (185
ft)-
raaiui,
had-
'arjo
been
obtained
ror placrng
concrete
on upstream
abutments
of
clay_
stone.
All
the
cranes
were
ilectrically
operated.
tching
and
mixing
plant
was
ment
by
I
I transfer
cars. A
lat
car
with four
3.06
cu
m
for
a spare
and
was
hauled
.
rf
80 H.P.
Concrete
wa!
-
vibrated
by
high-frequency
electric
vibrators.
.
special
motor
gr*ruting
ser; ;4i"0
and
20
Kl,
^gapa.9rty,
generated
electricity
for
these vibrators
at t.LU
votts
and
120_cycle
frequency.
steel
cantilever
forms,
fabricated
at
the site
of
the
ygtk
to.a
design
furnished
by BIaw
Knox
Co-puny
were
used
on
the
main
dam.
wood paners
were
used
58
rI
the
spillway.
apron,
galleries
and
training
walls.
Forms
were
raised
by
safety-puil,
ratchel-J;;;r,
chain
hoists
and
A-frames.
3.Ll
Penstocks
Fabrication
and
fnstallation
FTGURE
30
:
Photograph
showing
the
view
of
second
stage
of
tresfles.
Yelg_ht
of
the
penstock
assembly
was 33,793 kg
(74,500
lb)
(Figure
3l).
The
maximum
gradient
in
the
penstock
liner
u,as
39'
in
case of
penstock
Nos.
I to
9
and
44"
_34"
in
the
case
of unit No.
10.
The
total length
of
penstock
.
Trqnsportation
and
Installation:
The
transporta-
tion-.of
penstock
assemblies
from Nangal
workshop
to
Neilla was
done
by
a special
low
bed railway
wagon
and
from Neilla
ro the
dam
site
on
60.96
tonnes
(60
tons) low
bay.
At
the dam
site
they
were
handled
s9
::i,i
.'i
rt
FIGURE
3t
: Photographshotingthe
installation
of
penstocks-rnside
vierv
shoning
nelding
going
cn.
b-y
the-
revolver
crane.
Installation
in
the
blocks
is
shown
in
Figure
32.
-
The penstock
installation
in
the inclined
tunnels
in
the
case
of
left
power
house
rvas
done by
lowering
the
penstock
from
the
dam
blocks
on
,p..iully
desilned
trollies
rvhich
ran
on
rail
tracks
laid
^to
coriect
grid.t
in
the
tunnels.
For
the
rigrii power
housi
steer
for
penstock
fabricator
was
nor
uuiilable
in
time
and
consequently
blockouts
were
left in
the
concrete
blocks.
,.ff
tl...l penstocks
had
to
be
handled
up in
a
ver),
ormcult
and
tedious
manner (Figure
33).
The
individual
pieces
were
aligned
in
position
with
the
hglp-of
screrv-
jacks
ano
hoi-ding
doivn-toltt
witt,
turn
buckles.
As
the
liners
were
6verhanging,
the
reaving
used
for
pulling
was
also
used,
for
holiins
them
60
I
po-sition
till
sufficient
welding
of
the
joint
was
done.
The
faces
of
the
liners
were"matcheo
rvithin
a maxi-
mum
off-set
of
1.6.
mm.(1,16
in.)
using
dogs
and
wed-ees.
All
penstock
sections
were
electric"arc
welded
ano
successrve
welding
fillers
were
properly
cleaned,
"^h-lenA
and
peened.
-The
electrocles
conformed
to
Aws
specification
No.
E
6,010.
The
werd
seams
r'ere
radiographed
by.
Gamma
Radiographyui
,it.
*ing
a
portable
machine.
The
films
used
were
Kodak
'Industrial
Fil'rs
Type
AA
size
rl.4
cmx:a
cm
(4+
.x -1.5
in.)
and
the
whole
circular
jointwas
radio_
graphed
in
one
exposure.
The pro..riing
of
the
firms
was
done
in
the
dark-room
speciaily
pioviaed
at
the
srte.
Field
,srress
Relie,ing:
After
the rverd
was
found
to be
satisfactory
the
field
rvelded
joints
above
i.tz
.*
FIGURE
32
:
Photograph
showing
the installation
of
penstocks
in concrete
blocks.
6T
FIGURE
33 : Photograph
shorring
the
view
of
the
penstock
liner
having
hauled
insidc the
penstock
tunnel.
FTGURE
34:
Photograph
showing
the view
of
installation
of
turbines
and
generators
in
the
power
house.
(ll
in.)
thick
were
srress
ie
keepin*e
the
weld
relativelv
emoved
_by
a water
spray
frame.
plates
up
to
3.5
cm
I
one side gnl,v
rvhile
the
ras
applied
to both
surfaces
rly
opposite.
C-oncrete
Encasement
:
Allpenstocks
in
tunnels
and
blockouts
were
encased
in
76
"il
(z+
rt)
thick
concrete
and
the
cavities
u.t*.."'
ir,-.-tio.r
and
the
concrete
:-:1.
tested
by
-acoustic
tapping
and
grouted
at
pres_
t_Tt.
pr4ne
{.gq
l.a
kg/srii--to
4.i
kgirqlrn
e0
p.s.r.
to
60
p.s.i.)
dependiig
upoo plate
thickness.^'+h;
62
figrout
holes
were
suitably
plu-uged
and
welded
f,
starting painting
operatioir.'
-
-
rFr..qenstocks
:ve.re
provided
with
hemisphericar
steel
bulkheads
on
their
upst..um;il';;
r,"p;H.
enrry
of
Bhakra
Reservoir
*ui.i
;;lh.';;rT"'.?s
tlr
completion
of
penstocks
and
erecti"n
Jii"ruin.rraoa
generators,
etc.
on which
coaltar
primer
C 203-51
was
applied.
W
ably
dry,
the bond
test
was
performed
before
taking
up
bulk
enamelling
and
thus enamelled
patch
was
subjected
to
peel
test.
After
satisfactory results
the
coaltar
enamel
was applied
on
the
primed
surface
at
500'F
by
Hand
Daubing Brushes at
a thickness of
2.5
mm*0.8
mm
(3132
in.
*
ll32
in.).
As the dust
and
the
coaltar
fumes
are highly
poisonous
and have
deleterious
effect
on
human health, special
blowers of
capacity 311.5
cu m/min.
(11,000
cfm)
and static
pressure
of
37.5 cm
(15
in.) of
water
column
had
to
be
installed
to clear
the working
area. All
the
dust
and fumes
were
thus taken
out through
a
special
pipe
connected
near
the upstream end
of the
penstock
and
discharged
in the
atmosphere.
The
enamelled
surface
was
subjected to electrical
inspection
by
means of a
flaw
detector
bolt.
All
thinner
coatings
and
pin
holes
were
suitably covered with
enamel. The
life
of this
enamel
coating is
^about
30_
years.
Total painting
surface was
31,493
sq m
(3,39;000
sq
ft).
The.
entire
job
of
the
installation
(See
Figure
34)
a.nd
ppinting
wa_s
subjected
to
rigid
procedural-inspec-
tion b-y
an independent
agency
to
ensure
quitity
control
as
laid
down
in
the
relevant
specifications.
Cost
Data
Cost
of
steel
Cost
of
fabrication
Cost
of
haulage,
handling,
installation
at
site
and
welding,
etc.
Cost
of
painting
Rs. 124.8
lakhs
Rs.
25.0
lakhs
Rs.
41.0 lakhs
Rs.
32.2lakhs
Pu,rt fY-Initial
Storage,
Dfuintenar0ee
and
Operation
4.L Proposal
for
Early
Irrigation
In
view
of
the facts
that the
canal system
for
irrigation
was
already
ready
and there was
keen
demand
for
water
for
irrigation, it was
decided to
store
water
against
the
partially
completed
dam as
early as
possible.
The
early
irrigation
scheme envisaged
installation
of
temporary
regulation
gates
in
the
right
diversion tunnel. As
a first
step, the right
diversion
tunnel
was
closed by constructing a
coffer
dam
during
the
winter
season of 1957-58 and the river
was
diverted
through
the
left diversion
tunnel.
Outlets
were
provided
in a
temporary
plug
in
the right tunnel
and
regulating
gates
were
installed.
These
gates
were
worked
by
means of hoists
installed in
a
chamber
hallowed out
of solid sandstone
rock
above the tunnel
as
shown in Figure
35.
This
chamber
was
called
'hoist
chamber?
and
was
connected
to
the
dam
gallery
by
means of
an inclined tunnel
which
provided
access
to
the
hoist
chamber. The
left
diversion
tunnel
was
then closed
by dropping stop
logs
on 3
July
1958.
The water-level in
the
river upstream at that
time,
stood
a.t El. 345.46
m
(1199
ft) above
mean
sea lev-el.
During
this
period
a
regulated discharge of
255
cumecs
(9000
cusecs) or the
river
run-off,
whichever was less,
was
allowed to
pass
through
the
right
diversion tunnel
and
the
rest stoied.
Thus
was
started
the storage
of
water
for
the
first
time
in the
Bhakra
Reservoir,
called
Gobind Sagar.
Since spilling
over
the
partially
completed dam
during
1958
floods was
unavoidable,
two spillway
By
the
monsoon
of
1959,
the dam
had been
cons-
tructed up
to
El. 438.91
m
(1,440
ft)
in the
spillway
portion
whilst
some
abutment
blocks
had
been
raised to
El.
449.89 m
(1,476
ft)
above
mean
sea level.
Normal
water
releases
were
controlled
through
the
lower
tier
of
the
river
outlets
and
through the regulating works
of
the right
diversion
tunnel.
The
upper
tier
of
outlet
was
not
ready
yet.
4.2
f,'ailure of
Hoist
Chamber,
its
Repairs
and
Subsequent
Storage
In
August
1959,
when
the reservoir
stood
at
El.
436.17 m,
the water
flowing
through
the
right
diversion
tunnel damaged
the hoist
chamber.
The hoist
chamber
was
expected
to
provicle
adequate
control
until
the
reservoir
was
at
El.
449.8
m.
The
top
floor
above
the
gates
failed
when the reservoir was
at
El .
436 m.
The
gates
.were
bodily
lifted.
Nearly
255 cumecs
(9,000
cusecs) of water
escaped
through
the tunnel
-plug.
Water
entered
the dam
galleries
through
the
access
tunnel,
connecting the
hoist
chamber
with
the dam.
The
Left
Power
House,
where
turbines
and
generators
were being
installed, was
also
flooded.
This
was
the
63
-*1+J
"bj