Indian National Committee on Large Dams. Design and Construction Features of Selected Dams in India
Подождите немного. Документ загружается.
intake of
grout
was
seen, €.9., in
a total
depth
of
27.4
m
(90
ft) the
holes
took 368.11
and
253 bags for
3
successive stages
in the
case
of
block
14, reflective of
fracture
pattern
encountered
by
the
grout
holes
in
rock.
The
actual
grouting
was
started
with injection of
grout
mix as thin as
8
to
I
and changing soon
after
two
mixes
of
6 to l,
4 to l,
etc.,
but not
thicker
than
I
to l.
When
refusal was
indicated
by intake less than
9.1
litres
per
minute
(2
gallons per
minute)
at
the
specified
pressure
the
mix was
again
thinned successi-
vely until refusal
was
achieved
against water-cement 8
to
I
and
pressure
held
there
for
half
an hour.
For this
work
16,973 m
(55,684
f0 of diamond drilling was
done
and
44,240
bags
of cement
were
consumed.
2.8 Final Curtain
Grouting
(G-HoIe
Grouting)
[See
Figure
I
(b)l
Pressures
for
the
final
grout
curtain, varied
from
2l.l
kg/sq
cm
(300
p.s.i.)
from the top
of the dam
to
35.1
kg/sq
cm
(500
p.s.i.)
in
the
river
section. The depth
of curtain
varied
from
38.1
m
(125
f0
near
the
top
to
76.2
m
(250
ft)
in
the river
bed.
Holes
were drilled at
an
angle
of l1o
with
the vertical towards upstream.
The
curtain
was
finally
completed
by holes at
1.5
m
(5
ft) centres.
Initially, however,
as a first
sequence,
holes
were
drilled at
3
m
(10
ft)
centres
and
grouted.
The remaining
alternate holes
were
taken up as
second sequence
work.
With
a
view
to
avoiding
cracking of the
basal
concrete in
the dam
along
galleries,
pressure
for
the
first stage of 15.2
m
(50
f0
in
rock
was
limited
to 24.6 kelsq
cm
(350
p,s.i.).
Average
consumption
in
the
first
sequence holes
was
very
high, i.e., 7.41
bags
per
m
(2.26
bags
per
ft).
In
the
case of
the second
sequence
holes their
consumption was
found
to
be about 10
percent.
The work
of
G-Hole
grouting
has beenvery
effectively
done
as
indicated
by
test holes, one in
each
block.
Efficacy
has
been
further confirmed by low uplifts
and
negligible
flow
in
drainage
holes even
when reservoir
rose
to El.
506.3
m (1,661
ft) in
1964
as
compared
to
maximum
reservoir
level
of EI.
512.1
m
(1,680
ft).
For
the
work
of
G-Hole
grouting
34,377
m
(112,787
f0 of
diamond
drilling
was done
and
108,927
bags
of
cement were
consumed.
The
maximum
intake
of
grout
in
a
single stage
of
three companion holes was
1,719
bags in
block
ll
l12.
2.9
Foundation
Drainage
Drainage
holes
have
also
been
drilled
in
supple-
mentary
foundation
galleries
to
provide
water
pressure
26
relief
just
upstream
of
impervious
geological
features.
In
196I it
was
decided
to
provide
drainage holes all
along
the
toe
of
the dam
on
both
sides
from El.
396.2
m
(1,300
ft)
MSL
to
El.
488. m
(1,600
ft)
MSL varying
ggJrglpondingly in
depth
from
36.6
to
24.4
m
(120
ro
(80
ft)
parallel
to
chain
lines.
These
holes
have
been
drilled at
6.10
m
(20
ft) intervals
and
they
prevent
build up
of uplift
pressure
at
the
toe
of
the
dim.
z.LA
Mass
Concrete
and
Prevention
of Cracks
(a)
Block
and
Monolith
Plan:
The
dam,
a
mass
concrete structure,
has
been
constructed
systematicaily
according to a
pre-arranged
plan
of
blocks and mono-
Iiths
for
dealing
with
volume
changes
in
the
mass
concrete
produced
by
heat
of
hydration
generated
in
the concrete
afrer
placement
(Figure
9).
In
plan,
the
dam
and
spillway
apron
has
been
divided by transverse
contraction
joints
into
blocks
which
extend from
the
upstream
face
to the
down-
stream
face. These
blocks
vary
in
width
flom 15.2
to
18.9
m
(50
to
62.ft).
These
blocks
are
further
sub-
divided by longitudinal
contraction
joints
into
monoliths. These monoliths
vary
in
lengttr_from
lZ.l9
to
48.8 m
(40
to 160
ft).
The
longitudinal
joints
in
one
block
are
staggered
with
respecr
to those in adja-
cent
blocks. The
monoliths
have
generally
been
raised
in
1,829 mm
(6
ft) lifts.
Lift
Height:
The
height
of
lifts
is fixed
from
rhe
considerations of schedule
of
concreting,
relative
increase
in
cost of form
work
with
increaied
height
and coresponding decrease
in
the cost
of cleaning-up
of the
lift tops
and
cooling,
as
well
as
the
associated
savings
in other features
like
reduced
gallery
length,
etc.
From,
above consideration
for
a concrete
placing
temperature
of
18.3'C
(65"f'1a
lifr
height
of a 1,829
mm
(6
ft)
was
adopted for
Bhakra
Dam
instead
of
the
con-
ventional
lift
height
of 1,524
mm
(5
ft).
(b)
Strength
Requirement
and
Mix
Design:
The
mix
a4opted
for
mass
concrete
for
the
dam was
gover-
ned
from the consideration
of
the maximum
expected
compressive stress on
one
hand
and maximum
tensile
stress
on
the other.
While
selecting
the
type
of cement
the
extra cost
of
adopting low
heat
cement
versus
the
savings
in
the cost of
cooling were
kept
in
view.
The
size
and
grading
of
the
aggregate was
so
adjusted
as to
obtain
maximum
density
of
concrete
of
required
strength
with minimum
cenrent
contents.
Use
of
puzzolanic
materials
was
also
made
to
replace cement without
loss
of
ultimate
strength and
to
improve
thermal and
mechanical
properties
of
concrete.
Based
on
above
considerations
a mass
concrete
of
161.7
kg/cms
(2,300
p.s.i.)
28-day
cylinder
strength'was
adopted.'
In
general
the above
strength
could be
-*4'/
'*
achieved by using
3.58
bags
lm}
(2.75
bags
of cement/
cubic
yard).
Use of
puzzolanas
to
maximum
replacement
of
20
percent
was.
allowed. Air-entraining
ag.elt
was
alsoused to
reduce
the
water-cement
ratio
and
improve
the
workability
of the
mix.
The
possibility
of using
different
grades
of
concrete
in
diffeient
locations of
the
body of the
dam
was also
considered,
but since
where compressive
stresses
weie
low,
high
tensile
strength
was
required
due
to
beam
action
and
as
the analysis
of the dam
was
made
on
the basis of a
uniform
mass
of
concrete,
uniform
grade
of
concrete
was adopted.
High strength
concrete
was,
however,
placed
at
special
location
like
areas
around
river outleis and
pensfocks,
spillway surface
and
spill-
way
bridge
piers
to
suit
special
structural
requirements
at
these
places.
discussed
briefly
hereunder.
cooling.
(i) Final Stable
Temperature
within
the
Body
of
the
Dam:
The
final
stable
temperature
of
the
mass
concrete
in
the body
of
the dam
depends
upon
the foltowing
boundary
temperature
condi-
tions
:
(1)
Mean annual
temperature
of
upstream
face
of the dam.
(2)
Mean
annual
temperature
of
downstream
face of
the dam.
(3)
Mean
rock
temperature
along
the founda-
tion of
the
dam.
The
mean
annual
temperature
of the
downstream
face
and
the
portion
above
normal high
water-level
of
upstream
face
of
the
dam
was taken to be
the
same
ai the
mean annual
temperature
of the
air.
In
addi-
tion
to it the
effect
of
direct
sun
and
shade,
etc.,
was
also
taken
into account.
The
portion of upstream
face
below
normal
high
water'level
was
taken to
be at
mean
water
temperatuie
of the
lake.
The
variation
of
water
temperatuie
with
depth
and
due
to de-nsity
current,
etc.,
was
also copsidered.
The mean
rock temperature
was
considered
to be approximately
equal
to the
mean
air
temperature
although the seepage of
reservoir
water
through
the
foundation
may
lower this
temperature
somewhat subsequently on filling of
the reservoir;
The
effect of
openings
like
penstock,
river outlets,
etc., was
neglected.
On
the basis of the above boundary
conditions,
the final
stable
temperatures
within the
body of the
dam were
estimated.
(ii)
Thermal
Properties
of
Mass
Concrete:
The
overall
requirements'
and effectiveness
of
cool-
ing
system depends upon
the
thermal
proper-
ties
of
the
concrete.
Diffusivity is
an
index
of
the facitity
with
which
concrete
can undergo
temperature
changes and
is dependent on the
conductivity, specific
heat
and
density of
concrete. It
may be determined
in
the
labora-
tory from
a
test
specimen
or
predicted
from
knowledge
of
thermal characteristics
of
the
mix
components.
Although diffusivity
is
influenced by
the
mix ratio,
it is much morg dependent on mineral type
of
aggregate
and
sbnd
which
form
the bulk
of
mass
concrete.
The
aggregate
and sand
used
for Bhakra
being
principally
of
quartzite,
the
diffusivity
of 0.005
m2
(0.058
sq
ft)
per
hour
for
quartzite
was
adopted
for
making heat
transfer calculations.
The
adiabatic temperature
rise
of mass
concrete
due
to heat
of
hydration
depends upon
the
type
and
amount of cement.
As
mentioned earlier,
from
economic
considerations
standard cement
was used for
the
mass concrete.
Adiabatic
temperature
rise
curves
and mass
concrete
cooling
studies
for various
placing
temperatures
and exposure of
lifts upto
10
days
were
made
for
3.27
bags and 3.92 bags,tm'
(2i
bags and 3
bags
per
cubic
yard)
cement contents.
(iii)
Placement
Temperature of
Concrite: For
placement
temperature
of
mass concrete
the
following
three alternatives
were
studied.
(l)
Placement
temperature
29.4" C
(85'
F)
with low
heat
cement,
without
pre-cooling
but
with
post-cooling
and
longitudinal
joints
at
about 24.4
m
(80
f0 aPart.
(2)
Placement
temperature
18.3oC
(65'F)
with
standard
commercial
cement
and
post-
cooling,
with
longitudinal
joints
at
about
30.5
m
(100
ft) apart.
(3)
Placement
temperature
10.OoC
(50"F) with
standard
commercial
cement
and
without
post-cooling,
no longitudinal
joints
and
hence
no
grouting
of
contraction
joints.
Alternatives
(l)
and
(3)
were rejected
from
econo-
27
mic
considerations
as
well
as
due
to the fact that
experience
in
United
States
of America had
demons-
trated
that
best
control
of cracking of
concrete
during
early
age exposure
is obtained
by a
low
initial tempera-_
ture.
On
the
other hand
placement
temperature
of
10.0"C
(50"F)
was
considered to have the disadvan-
tages
of
requiring
shading
and
insulation of
the
fresh
concrete
surfaces during
summer months
and
even
discontinuation
of concreting
operations
during
very
hot
periods
of
the
summer
days. Also experience
of
construction
without
longitudinal
joints
was limited
to
medium
height
dams only
and the scheme
had
no
flexibility
and
subsequent control
on the temperatures.
As such
alternative
(2)
above
was considered
to
be
most
suitable
and
a
placement
temperature
of 18.3"C
(65"F) with
post-cooling was
adopted.
The final
stable temperature
of the
mass
in
the dam
was
expected
to
be nearly
18.3"C
(65'F).
Final
temperature
at
the end
of cooling, therefore,
could
be
from
15.6'C
(60'F)
to
18.3"C
(65'F).
Temperature
change
required
to open
contractions
joints
during
cool-
ing
would
be
abouf-3.9"C
(25"F)
to-I.l'C
(3q"F).
Temperature
rise
following
placement.was
expected
to
be
about
4.4"C
(40"F).
The
placement
temperature
had,
therefore,
to
be about
18.3'C
(65"F)
wit!
a
view
to
limit
the
maximum temperature
to 35oC
(95'FJ
and
also
to ensure
opening
of
joints.
'fhis
could
be
readily
obtained
in
winter season
without special
cooling
measures.
During
summers
when
normal
concrete
temperature
without
control,
would be close
to
32'2-C
(90"Ft
refrigeration
was
applied
to
obtain
the
desired
value.
Introduction
of
ice in the
mixers
did
not
afford
sufficient
control.
To
reduce the
placement
temperature
to
18.3'C
(65"F),
the
method used in
practice was
the
cooling
'of
coarse
aggregate,
which
was
sufficient
to
produce
desired
temperature
without
additional
medsures.
Inundation
of
coarse
aggregate
in
refrige-
rated
water,
has
been
used
successfully
at Bhakra.
Procedure
adopted
is
described
in
part
IIt.
A
joint
opening
of
at
least 1.27
mm
(0.05
in.)
was-
obtainid.
Thus,
constant
placing temperature
of
approximately
18.3"C
(65"F)
throughout
the
year
made
the
whole
set
of
desirable
conditions
consistent.
obtained.
The cooling
system
adopted,
in
general,
consisted
of thin
rvalled steel
tubing
placed in
parallel
circuits
with
1,524
mm
(5
ft) spacing
on
top
of each
1,829
mm
(6
ft)
lift
previously
placed. The
tubing
was of
25.4
mm
(one
in.)
outside
diameter
for
the
main
cooling coils and
38.1 mm
(1+
in.) to
50.8
mm
(2
in.)
for
the
headers.
The
thickness
of the
tubing
28
was
kept between
1.47
mm
(0.058
in
)
and
2.03 mm
(0.8
in.).
The
tubing
was
tested safe
for
a
pressure
of 3.52 kg/cm2
(50
p.s.i.)
and the coils and
the
field
connections
for
1.76 kg/cm2
(25
p.s.i.).
The
cooling
pipes
were
laid
in
independent
circuits
served
by a
supply
and
rbturn
header,
normally,
a circuit
did
not
exceed
365.76 m
(1200
ft) in
length.
The
cooling.
was effected
by circulating
river
water
at
a temperatuie obtainable
in the
river
at
a velocity
not
less
than
0.61
m/sec.
(2
ft/sec.). The
cooling
was
confined
to winter
months
unless
required
due
to
limitations.imposed by
grouting
when
circulating
water
was cooled
to
about
12.8'C
(55"F).
The
extent of
cooling
required
was
determined
by
observing
the
temperature
of concrete
by
resistance
thermometers
inserted in cooling
pipes
or embedded
in
concrete.
The
temperature
was measured
at
a
distance
of
about
7.6
to
9.1
m
(25
to 30
fO
from
the
exposed
faces and about
36 hours
after
stoppin-e
water
circulation
in
the coils.
The
cooling
was
done
from
the downstream
face
in
the
abutment
section and
from
the
galleries
in the
spillway
beginning
with-the
fourth
lift
above
the
supplying
gallery. This
arrangement
provided time
for
the
removal
of forms
from each
gallery
before
connec-
tions
for
the
cooling circuits
were
needed.
No
tubing
crossed tire transverse
joints
except
to
reach
the
mass
concrete
in the excavated
clay stone
stratum
in
the
canyon
walls.
Where cooling
pipes
crossed
longitudi-
nal
joints,
an expansion
type
coupling
was
provided.
had served their
purpose.
(v)
Sub-cooled
Concrete:
In
certain
portions
of
mass concrete,
e.g.,
the clay
stone strata,
shear
zone
trenches,
and spillway
apron,
neither
cooling
pipe
could be
conveniently
provided
nor could
joints
be
left
from structural
and
field considerations.
In such
portions,
specially
pre-cooled
concrete
has
been
provided.
This
concrete
was
placed
at
a temperature
of 10.0"C
(50"F)
to
12.8'C
(55"F)
to
keep
the
shrinkage
to
a
minimum.
This
was achieved
by cooling
the
aggregate
to
3.3"C
(38"FL
-dqllg
hot
weathei
and
using
water
at
1.7"C
(35'F)'
2.ll
Contraction
Joint
Grouting
Corc
vo//
5Ss-St2O
a
18
vs
li
x{
1v
o
s
!i
+
+
q
s
R
5
\*f
q
o
h
I
t
$
s
o
a
I
.o
d
h
os
.d
yt
Assunea/
loe
hhc.
,ttusr.J
lte
lti*
a
tt*l.4o
Sta
il++S
Concrelt
ta
dtm
te
o
ln
ii
dS
it
o
r)
t
s
I
!
t
t
!
\,
s
I
te
.d
'd
ln
rfi
b
\o
+
o
{
v
F{
Y6t
x68
Ii*
;ii
t
n
ri
b
+
I
(
\)
,J'ry'og
a
.A
€
Slo.
BtSo.oo
L
'o
-o
q
to
.A
\o
Sta
t6tt6.o0
t
.i
UI
t
V1
,6
'6
Vr
:t
n
.6
'$
o\
+
sl
t
g
t
s
ft|
t
q
t
u
rS
ol
s
Ol
tn
fl
I
fl
-s
st
s
\JI
a
o
o
n
t
t
t
\,
1te.1-0_.j2.oo
!
a
o
:
x
(
I
a
\
o
:
x
{
Longiludinal
jotnt
Ch
tS+65.00
4L
7'E
penstoc*
r
-
,,
.-_51a.
lt.J1.oO
Pastar
Pla
nt
I
I
I
I
tto. il.t+
oo
J
DETAIL
X
5rerroNAL
PLAN
Et
t+os.oo
Lcft
5pilttoy
homing
vo//
tnnar
?oca
Sto iltgo.OO
Ce
nhd
portion
rotl
Slo
r*20.OO
Slc.
tStTO.AO
'-4ighl
spillvcy tl.idn, wou
inntt ltcc
9t,
l4*.l0,OO
El.
rttos.oo
-
;niliot
srcgt
ol
cutcnthg
for
powtr
ptonl
l
-Povot
Ftonl
Z
t apra
n
_=F_+
longiludinal
joint
of
Pcntlock
Pansfoct
r
5EC
T
ION
A-A
SC
AI
SCA L
BI
Lpngitudtnol
1ot'nf
of
Flatt..,
\
t.,
o
{
a
29
I
ongiludinal
joint
of
P.r1
Slock
,nt?ocb
r
;€
penstoct
r
-
)
.__Sla-
tt.t+.o0
scALE
0
t,oo
t tttt
te
j
ScALc
1
,.._^:t,o
,::,rr'
DE7A,L
X
5f
CTtOx
A-A
BHAKRA
OAM
BLO
CK
L
AY
OUT
PLAN
FI6URE
9
d
iotnt
Ch
l5+65.00
iotc
f,o.clllL
6laasut_.itB
t-
,Li.
(t5-A-t37)
ill
tls
nn
NLET
PtP€
FOR
0UTLETS
AT E/,B2O,OQ
t"ob
o,rncoai)l
lt:;:.
-
dn1lrrc.50
(d*g
il:t'zat)
5EC
TlONAL
EL
E
VATION
erce
for
tlS
Air
inlet
P?es
of
Pivar Outtel5
of
Ell32O'
1cli,r,
for
thtchorc
snivn
n
vies
otlcft)
CONTNAC
NON JO4NT
CRO,S4N6,
El:/420'00
(T
YPlC
AL)
CONTRAC|ION
JANT
CROSSING
Et tJ20
00
(f
YPtcAL
)
Q,lt215rll'
'C
Onrr
oc
tion
Out
Outnt
of
ll,
'Z'Typc
motol
tad/}t
,lr
eult0
ELEYAT|ON
AT
LON&ruUHAt
Jolt(T
(Et
tl2O
Oo)
'lyPO
nrclOt
,ro.il'q
tl"rt.
ol
hfl ft
t
TLTVATION
AT LONilTUOI,U
JONT
(Et
/J2O'oo)
onduil
't20.o0
iron
ltnq.
tf
lr'fl
H2E
rq
of
tift
Et.t332
Top
of
lif
t
a(
er.nu
an
Et
tJ20'OO
'Z'Ttpc
actol
tcoh'ng
strlP
of
lif
t
El.
ri4
lp
of
tlft
EI,IJOE
(antroction
jont.
Top
oflift
Et./tt!\.
SEd
cot
dult
hact,
Controcfi'on
J'oint.
(
2:
I
I
I
I
I
I
I
I
.
,...
I
,-f
...": I
i,ii
(r.
--
Q. c,
- Ett
t
frl
/
:2
F;;;i'-
"'ii:ei
;=-
,
(t5:47!4-;_r
=':.'.1
8'O/-CA
-Ol
of
lif
,
Et rl2
'o
7.
a
l
a
a
\
L
e
.H,gh
6tu*
';
'j'
,
ot
€lhou rcAion!.
P
(u-A-e44)
Eyc&or
4fEctoe
(9.
6'h-
At
Stpply
Ar
'
(JN)s.
for coctt &trbr)
A.A
,^aaf
v'Jv
21'Ib cootha'oog lttrd
hc&, to
EUJU.tT
Ft
dctoils of
CorrtEctlon
Sa€
Afoil'X'q,
O*g.tt4-92t.
(E-A-,o
dtt r*11'
tfr| of trcroitTg
voltt
(Fetnils
tca
dwg.
rr-A:t41)
lop
d
tttt
Et tq6
bdcs
froa,
'ZtTyp
aot
2'-0.ot
AttEr
att
scoilte
t
lo
zcro
ot
I
Asbestos
OETAL
&Ost
oailGt
st
fantr@tion
joint
(Fe furasr
de
ra6
scc
dry.ll-A-a2)
(not
to
xote)
.fEcnou
SECNON
G.G
FOR
ELOCT(
ts
(oPP.
,tAilo
FoR
gloct(
22)
l'll9-===
I
SECuON 6
-
G
FOR
6LOC^$
ptfu
30
SECTIOH F.F
TOH
G.G
ocr( rc
I
FOR
ELOCK
22)
7rO
>oilt
,1)
20 FEET
Ft dcfoils of
COlr.ECtlOn
Sc€
Afoil'X)
ot,
0*g.tt4-92t.
BHAKRA
DAM
RIVER OUTLETS
sEcT f
oNs
FIGURE
IO
'1,1'1!trl
joint.
In
the case
of
transverse contraction
joints,
12.7 mm
(t
in.)
risers running
along
alternate
keys take
off from the
return
headers
placed
near the bottom of
the 16.5 m
(54
f0
grout
lifts.
The
grout
outlets
are
spaced
to
serve
about
6.69
sq m
(72
sq
ft)
of
joint
area. In
longitudinal
contraction
joints
25.4
mm
(l
in.) risers
taking off from
the
return
headers
near
the
bottom
of
the
grout
lift
are
placed
vertically at
both
ends
of
the
joints.
Grout outlets
are
provided
on
12.7 m
(*
in.)
horizontals
which connect
these
25.4
mm
(l
in.)
risers
and
are spaced to serve
about 4.46
m2
(48
sq
ft)
of
joint
area.
Grouting
of all
the contraction
joints
in
the
spill-
way
portion
of
the dam
was
performed
from the
galleries.
The
contraction
joints
in the
abutment
sections'were grouted
partly-from
the
galleries
and
partly
from
the downstream face
of
the dam
depending
upon operational
convenience and economy.
(a)
Grouting
Lrfts:
As the height of the lifts
had
been
raised
from the normal 1,524
mm
(5
f0
to
1,829
mm
(6
ft), it was not
possibletohave
15.2m
(50
ft)
grout
lifts.
Consequently,
adoption
of
14.6
to
16.5
m
(48
to 54
ft) and
18.29
m
(60
ft)
grout
lifts
was
studied. The
18.3 m
(60
ft)
lifts
did
not
suit
the
location
of
galleries
in the
dam
which
had
been
fixed
from
operational
considerations
and
14.6
m
(48
ft)
grouting
lifts were not
suitable
from
economic
consi-
derations.
16.46 m
(54
ft)
grouting
lifts
were
found
to
be most suitable
and
were, therefore,
adopted.
(b)
Grouting Schedule:
After
the
concrete
had
cooled
and
the
joints
futly opened,
the
grouting
of
the
longitudinal
contraction
joints
proceeded
from
abut-
ment
to
abutment
and
was
taken
up
in
separate succes-
sive
grout
lifts beginning
at
the
lowest
foundation
and
finishing at
the
top
of
the
dam.
No
grouting
was
taken
up
in any
grout
lift
until the
concrete
had
been
poured
to a
minimum
height
ofl
18.3
m
(60
ft)
above the top
of
the
grout
lifts
proposed
to
be
grouted.
The
grouting
in
each
grout
lift was
completed
before
the
height
of
concrete
above the
top of the
grout
lift
being
grouted
exceeded
43.9
m
(144
f0
as this
gives
_a
better
stress
distribution
in the
foundation
and
is
in accordance
with the basic
assumptions of
the construction
pro-
gramme
for the trial
load analysis
of
Bhakra
Dam.
The
grouting
of
contraction
joints
in the
following
special
locations
was
taken up along
with
grouting
of
the
longitudinal
joints
:
(1)
Portions
of
t^ransverse
contraction
joint
between
the
double
metal sealing
strips
near
the
upstream
face
of the dam.
(2)
The transverse
contraction
joint
station
l1
+90.
(3)
Areas of contraction
joints
between double
metal
sealing
strips
around
galleries
in the
spillway
apron.
(4)
Transverse
contraction
joint
area
in
upstream
clay-stone,
first
stage
concrete
beyond
ihe first
longitudinal
joint
from
axis
of dam.
(5)
Transverse
contraction
joints
of the
bed
rock
tift.
As a result
of
the
trial
load
twist
analysis,
it had
been
recommended
that
transverse
contraition
joints
of
main
dam should be
grouted
with
the reservoii
level
at El.
512.1 m
(1,680
ft)
MSL,
i.e., the
maximum
reservoir
level.
(f
)
The Gro.uting
Operation:
Usually the
day
prece-
ding
the
grouting,
the
joints
were
washed
thoioughly
by
forcing
water
and
compressed
air
through
-th-e
grouting
system
until
the effiuent
at
the
drain
headers
leaks,
if
any. Immediately
after
the
water
tests,
the
leaks that
could be
approached
were caulked
with
lead
wool.
The
joints
to
be
grouted
were
left filled with water
until
just
prior
to
grouting
on
the
following
day.
Ilnmediately
prior
to
grouting,
tJre water
was
drained
from
the
joint
to be
grouted.
with
valves.
The
vent
returns
and vent
lines
for
joints
3l
-,)-J
'r