Indian National Committee on Large Dams. Design and Construction Features of Selected Dams in India

material

in

30 cm

thickness.

For

protecting

the tyres

from

the

angular sharp

stones,

etc.,

two

pilot

passes

of

plain

rollers

were

applied.

Nearer

borrorv areas

were

explored

and exploited and by careful time

motion

studies

and better combination

of excavatine hauline

equipment.

The

progress

of

productive

earth

work

on the

dam considerably

increased and

the

work

was done

at

an

average

rate

of

above

28,300

cu

m

per

day.

During

the

whole

working season 13.47

million cu

m

of

production

and 1.13 million cu

m

of auxiliary earth

work

were

carried

out.

tr5.

Construction

of

other

Appurtenant Works

15.1 Masonry Dam

and

Spillway

The

construction

of

the

masonry dam

as a whole

was

divided

out

as

under for

the

purpose

of

letting

out

the work

on B-2

tender contracts.

(a)

Construction of R.T.

Dam

(b)

Construction

of H.R.

Dam

(c)

Construction of Spillway

(d)

Construction

of L.T.

and

Porver

Dam

Rs. in

crores

2.03

0.80

8.19

4.14

According

to construction

schedule for

1968-69,

the

spillway in

the

diversion

channel

portion

was

to

be

ready

with

masonry raised to El.

50.902

m

and

in

the remaining

reach,

the

masonry dam raised

not

less than

El. 73.152

m which

corresponded to

the

elevation

required

to

pass

the

maximum

incoming

flood of

49,500 m3/sec.

By

the end

of the next

year,

i.e.,

1969-70,

the

spillway

was

to

be raised El. 91.135

m

with

a

gap

of

156.06

m

left

for

the

passage

of

flood.

In the

working

season

1970-71

the

work

was to

be

completed.

The

power

dam

works

being

difficult

and time

consuming were to be

isolated

by

an envelo-

ping

ring

bund

for

purposes

of

diversion.

The

work

went ahead

generaily

according

to

the schedule

they

were

ready

for

catering

to

the

diversion

of

the

river

by

June

1969.

The

spilhvay

and

,non-overflow

dams

were

cons-

tructed in

mass random

rubble

masonry,

in cement-

surkhi mortar

in

proportion

of 0.8 :

0.2

: 5.

by

weight.

A

width

of 1.83

m

on

the upstream

face

was construc-

ted using a

richer mix

of

proportion

of

0.8 :

0.2

: 3

by

weight.

The

specified strength

for

the

lean

mortar

was

84.37

k-eicm2

at

90

days.

The

masonry for

the dam

was

laid

using

skilled

masons

from

Saurashtra,

Khandesh,

Uttar

Pradesh,

etc.

The

masonry

work

was

executed

as

usual

on

a

pair

basis-one

mason laying

the

masonry in

front

and

the other

behind

helping him

in

tamping mortar

in

the

joints,

insertion

of spalls,

pressing

of

joints.

There

were

separate

skilled

u'orkmen

for

the

face

work.

A

peak

total

progress

on

masonry

of 1982

ctt m

per

day was achieved

in

the

season

1968-69.

The

work

of

construction

of

spillway

involved

540,000

cu

m

of

masonry rvork

and

167.00, cu

m of

concrete. The

1'earl1,

outputs were

as under

:

Year

Quantitl'

of

Iltasonr)l

(cu

m)

Quantity

of con-

crete

(cu

m)

1967-68

I

968-69

1969-70

r9'.70-7

|

r97

L-72

Total

93,400

1,64,200

145,700

132.700

4,200

9,1 00

22,100

54,300

49,200

32,000

5,10.000 167.000

To achieve

the

targets

in

the

peak

period

as

much

as

1,133

cu

m

masotlry

and 396 cu m of

concrete had

to

be

laid

per

day.

The

rubble for

masonry

was carried

by truck-dumpers

and

unloaded

near

the

upstream toe

of

the

dam.

It

was

lifted

using simpie

jib

cranes

capable

of lifting

I

tonne,

i.e.,

0.71 to 0.85 cu

m

of

rubble

at

a

time.

These cranes

could be

erected

and

dismantled

u'ith

ease

and

shifting even

on

a

rveek

to

week basis

if needed

could be

done

without

difficulty.

The

mortar

was mixed

in electrically driven

mortar

mixers

of

0.02

cu

m

capacities

placed

at suitable

loca-

tions

near

the

blocks to

be raised.

The

mortar

was

hauled

up

using

rvinch

driven

buckets sliding

on

hoist

towers.

The

buckets

had

a carrying

capacity

up to

0.423

cu

m

of

rnortar.

The

rvinches were driven by

15

H.P.

electrical

motors.

Thus

the

significant

feature

of

the

plant used

at Ukai

for masonry

dam

works is

that

the units

were

small

but they

were

flexible and

this

suited

admirahle

the

job

requirements

which

necessarily

stipulated

frequent

shifting.

Wjth the

peculiar layout

of the

works at

Ukai

rvhich

involved

complicated

diversion

of the

-river

with

elaborate

pro-

tective

works,

(all

with

tight schedules)

and

wjth

a

ring

bund

enclosing

the

porver

dam,

there

were

severe

restrictions

on available

rvorking space

and

any

attealpt

at centralisation

of feeding

plans would

have

resulteC

in to

costly

delays.

For

the

spilhvay

rvork

as

a

whole concreting

to

the

tune

of

1,67,358

iu

m

was involved.

The

following

279

three

forms

of

centring

which

were

easy

for

erection

were

used

:

(a)

Specially

prepared

curved

centrin_e

of

M.S.

channel

templates

for

concreting

of"i.rit.t.

(D)

S.imple

steel

prates

herd

by

borrs

and

internal

ties

for

ordinary

concrere

not

exposed

to

permanent

finish.

(c)

concrete

truss

type

centring

with

steer prates

for

permanently-

exposed

"ruriu..;;;..

for

:|?gjrg.

surfacei

or

'for

verrical

surfaces

of

prers,

etc.

The

concrete

carried

out

for

the

spilrlvay

consisted

of

the

following

different

-i*.i

,

in

all

cases,

though

for

some

tip_e

a

monotower

crane

with

a boom

lengih,

i."grir^'^ij.SO

m

was

used.

Con_

creting

to

the

ex-tent

or

5g6

Jri

p.,

day

was

done

on

this

project

by

placemin;;.;il;o.

trmes

made

dents

in

c

.l

p

mm

which

could

not

-

blasting

method.

Also

the

Dlastrn_q

was

not

a

problem

his

work

involved

construc_

le power

dam

which

houses

:

river

bed

power

house.

)nry

and

concrete

on

the

Season

Quantity

of

masonrv

(cu

m)

Quantity of

concrete

(cu

m)

Class

Location

Slump

Max.

Min.90

da1,s

(cm)

aggregate

strength

srze

(kg/cm

j)

(cm)

7.60

2.50-

5.10

7.60

1967-68

I 968-69

1969-70

1970-71

L97L-72

22640

99050

1s4230

97070

28870

3.80

1.90

2830

9340

r8560

14550

4.2

Pier

A.4

Galleries,

adits,

sluices

control

well,

contraction

joint,

beam

at

offset

A.5

Wearing

coat

B.

Crest,

d/s

face

of

spillway,

bucket

end

sill

C.

D/s platfonn

beyond

end

sil

I

A.3

Columns

and

beams

above

neutral

axis

A.3

Beams

below

neutral

axis

2.5

1.90

2.50-

7.60

5.

I0

250-

7.60

5.10

5, r0-

3.80

7.60

211.0

211.o

21

1.0

176.7

5

r41.0

Min.28

da-vs

strength

200.0

kgicml

200.0

kg/cm2

40r

860

45280

Considerablq

.gr9l9my

has

been.

effected

by

speci_

fi'ing

the

mix

of

17.6.oo

[glcm;"

i*

^irr.'^"gi.

,'"0

rhe

bucket

of

the

spillway

itrri"rt

arong

u".Juntr*

for

40

percenr

of,

the

to_tal

concrete.

The

c6ncretinJ-was

done

fsing

mixers

of

capacirie,

,".yi"g

^i;;;"6.;s

cm

ro

0'4

cm.

Mixed

conciete

was

rifted

"urio!

*i"nJil

o.i".n

hoist

buckets

sliding

;r

--

h;i;r

towers

as

described

earlier'

The

pracern-nr

of

concrete

was

done

manua'y

280

upstream.

The

materials

of

c

similar

characteristics.

Th;-

concrete

prant

deproyed

for

raising

-of

masonry

and

concrete

were

sim'ar

to

that

for

spillway.

The

construction

of

the

L.T.

and

power

dam proved

to

be

more

difficult

in

many

respects

than

was

antici_

:am

of

the power

dam

the

work

'

rogress

since

1967.-

In

the

was

also

required

to

be

the

raising

ol

the

earthen

Lot proceed

further

till

the

rised

in

advance.

l,+-;-..-,a..,

Construction

of spi lhvay.

281

c

rYtlr

PHOTO

7: Construction

of

sluice

nork.

,

Of

special

interest

in

ga-T

construction

rvas

th

bell-mouths

and

transitior

While

the

beli-mourh

upstream

the

concrete

arol

penstocks

was

started

fro

house

end).

A special

trac

columns

was

laid

at

El.

73

to

the

level

to

which

ttre

masonry';;;,.;;;iJ;;;;

the

sides

in-between

the rinerr.

b-on;r;il;g-;uiton.

uy

y.sing

trolleys

witf

hinged

tiriing

buckets.

concrete

was

started

from

the

downstream

end

a;J;;r;;;;;;rsivel'

carried

forward.

r' $e

vrvsr'

.

15.2

Gates

(i)

Radial

Gate

:

Fabrication

and

erection

of

radial

gate

is

dong

through

vrii

r

s.p.

ito.,'i"c.nt.ut

Government

Undertakinf.

'

(ir')

Gantrt,

Cranes

:

Fabrication

and

erection

of

60-ton

and

i0-tor,

*i."rly

..un.,

-

ur.

under

pro_qress.

Work

is

let

out

to

tuf

,

i.S.ir.

f-td,,

a

Central

Govern_

ment

Undertakin-e.

75.3

Power

House

The

size

of

pou,er

housr

22

m

wide

and

52;

iri;h

n'rent

required

.for

the

i..

nously.

Turbine

_seneiat,

and

later

on

maintenance

,nd

other

equipment,

two

rated

overhead

travelling

nside

the

main

Uuilding-o?

15.4

Construct

ion

D

etaiis

tecessary

to

excavate

up

to

und

level,

mostly

in

rock

bines

and

generator.

For

g

ramps

had

to

be pro_

like

polver

shovels,

clamp

lumpers,

etc.,

had'

to

be

required

depth.

rhe

strata

.lng.

^ _ _Cr.rt_.

stoplog

was

fabricated

throu,eh

a

local

agency.

The

trial

operation

is

yet

to

be

d;;;.^

Hydraulic

hoist

for

these

_eates

courd

not

be

manufactured

in

India.

Hence

^

a

gtobal

tender

\r.as

invited

and

finally

it

was

manufactilJ-;ri

installed

b1'a

French

agency.

(iii)

Outlet

Gate.s

and

Stoplogs

: These

gates

and

stoplogs

were

.fabricated

and'eriected-

bt

-rh;

local

contractors.

282

specrmen

samples

of

concr

16.

Structural

Behaviour

of

Earth

Dam

Instruments

are-embeded

in

four

reaches

of

ukai

eartlr

dam,

viz., (t)

Righr

bank

.uiiir-o"i","tA

Main

PHOTO

8 :

Construction

of

generator

room

of

power

house.

gorge

earth

dam.

(iii)

Earth

dam

betu,een

Hill

Nos.

1 and

2,

and

(iu)

Earth

dam

between

Hill

Nos.

2 and 3

tg

study the

influence

of

various

parameters

on

the

structural

behaviour. pore pressures

were

measured

in

some cases

by

Mahiak

make

vibrating

frequencl,

tube

transmitters

and

in other

cases

by

U.S.B.R.

hl,draulic

r)'pe

piezometers.

Surface

settlements were

measured

b1'

surf'ace

settlement plugs.

Internal

settlements

\\'ere

measured

by

cross-arrl

installation

and

foundation

settlements rvere

measured

by

base plates.

The

Iist

of various instruments

installed

is

given

in

'Iable

XVI.1

M.G.E

D

R.B.E

D.

ftil**,-

uoX1tjil"

Hill

Nos.

Hill Nos.

1&2

2& 3

TABLE

XYI.l

Instrument

s

Piezometer

tips

Cross-arm

sets

Base

plates

SLrrface

setllement

plugs

.+6

2

12

66

1

)

62

2

o

30

27

I

L2

283

PHoTo

9

:

Construction

of intake

structure

of

poner

house

from

upstream

pond.

l6.l

Pore

pressure

-

The

maximum

observed

pore

pressures

in

construc_

tion

condition

and

in c.ato

c6*r

.orioll*

ui.

-!iu.n

i'

Table

XVI.2

for

ali

earrh

dam

sections.

Tfr'e

pore

pressures

beiow

the

lo*, *'ater-level

and

above

top

seepage

line

in

operation

condition

usually

compared

to

phreatic

Iine.,

DS-ti_il

pore

pressures

an-d

pore

pre-

sty.r:

computed

by

Hilf's

methbd

from

undrained

ion_

solloatlon

tests

in

laborator),

are

also

given.

_The

observed

construction

pore

pressures

are

of

the

order

of

70

to

100 percenr

for

ali

three

zones.

i.e.,

impervious,

semi-pe.i'iout

an,i

random.

The

observed

pore

pressures

in

drarvdo*,'

range

and

in

operation

condition

also

show

maximum

pore

pressures

in

the

t.

Tlie

lou,pressures

(5

to

us

zolte

in

main

gorse

earth

3r'r'ed

after'

dissipitio-n.

The

"t

"'

AH

tt"r'

? J,

;'.':,1

i,::,

-'

.

The

construction

ard

operation

pore

pressures

jn

impervious,

semi-pervious

ii

Gr

as iardom

,on.,

u..,

therefore,

consideied

to

reach

a

value

,oir.rponOing

to

100

percent

height

of enlbankment.

284

76.2

Settlement

The

obser'ed

internal-

foundation

and

surface

settlement

are

summarised

below

:

Settlemeni

R.B.E.D

M.c.E.D.

Hiil

Nos.

1&2

Hill

Nos.

2&3

Internal

setr

le-

ment

Founclation

settlement

!

"1o.of

0.5%

llelgilt

2 to

1.2"/

2%

1.28yo

About

3%

for

12

m

height

o.e%

1.0%

Surfl:ce

setr

lement

1l

for

12m

height

The

i'ternar

as rveil

as

foundation

settrement

ha'e

thus

bee'obser'ed

as

about

I

percent

of

height

of

enrbankmenr.

*'rrich

js

rhe

p..r.,ri

o.riln^'iia.ti...

The

surface

settiement

fcr

ior'

heighti'rruil

been

obserred

as about

-3.percent

but

as

these

observations

are.likely

to be

initiated

by

surface

activities

of

machi_

neries.

erc.

They

are

nor

consideie;

;;"

i.pr.r.n_

tative.

TABLE

XVI.2

Observed

pore

pressures

Zone

Design

pore

pressure

Const.

&

SDD

condition

(percent)

Construction

pore

pressure

by Hilf's

method

R.B.E.D.

M.G.E.D.

Hill

Nos.

|

&2

Const.

Draw-

down

o/

/o

Hill

Nos.

2&3

Const.

Draw-

down

oi

o/

/o

Const.

o/

/o

Draw-

Const.

Draw-

down

o/

/o

1I

r0

Imper-

vious

Semi-

pervious

Random

100

75

100

80

2s70

70

20

80

100

80

l0

2l

:20

to

oo

90

80

lrc

160

r6O

>5

22

2tl

20

r9

r8

tv

16r

r6(

>l

.3

I

o,2

o

(e

:)

bl

6r

E

-t

$r

e

!u

q

-{

tr

|r

tl

o

ao

r'

M

J

A

S

O

970-

Tip

R.L.

IRefere

FIGURE

9:

Pore

pressures

in

construction

condition

(I.P.

Zone)

at

Ch.

E925

of

M.G.E.D.

285

Resiarroir

levLi

'o

808

o

7c-2

E

c

6

.9

6

L

$f

o

(I

360

320

280

240

200

'60

t.o

o.8

o.6

o4

o.2

o

lrl

F-

I

9

7l------1.-

I

9

7

2--J-

r

9

z

3_-]-_

I

9

74

_+_t

9 7

5

-+re76--frs77--

Period

FIGURE

10

:

Pore

pressures

in

operation

condition

(I.P.

Zone

Tips

3,

5,

6, E,

9,

r0,

&

r2A)

at

ch.

g925

of

M.G.E.D.

ilo

too

90

60

50

il

9

o

tr

17.

Reservoir

Operation

The

yearly

average

rainfall

in

Tapi

basin

from

1971

to'197g,

varied'

from

500

to

900

mm.

The

year-wise

monthry

infiows

and

outflows

ui.

giu.n

in

Table

XVII.I

286

during

September

and

aft

rated

to

a

safe

discharee

trol

space

available

b-elo,

the

outflows

from

the

rel

conditions

shall

be

restricted

to

i,

The

ourflows

would.

be

gr.ut.,

than

24,670

cumecs

if

the

reservoir

continuesi"-iir.

after

crossing

F.R.L.

El.

tos.t5

m.

rt

woutd

thus

be p;r;ibi;

;;il:

floods

with

peaks

betrveen

33,9g0

to

4g,5s5

cumecs

rvith

rnaximum

outflow

ranging

from

24,67a;;3;,ii;

""mecs

even

when

standard

project

flood

.r

+-g,sbti

cumecs

impinges

at

F.R.L.

under"ideai

conditions.

For

extre-

mely

rare

conditions.

of

probabre

*uiio,uo,

flood

59,918

cumecs

rmprngmg

into

the

r.t.iuoi,

u"i'e.n.r.

El.

I 05.

I 5

m

the

e,ipfrasis

rviil

il

-io-;rl?.r,

the

headworks,

at any

cost.

The

reservoir

revels

actuaily

maintained

are given

earlier

in

Fisure

10.

The

p.if,ormanr.-

t?

ltir-,r-p

bucket

is

shoiln

in

pl,otofl.'"'

In

case

of

scare

years

occurring

after

fuil

estabrish-

ment

of

irrigation

of

over

tlsz,ooo

rt..iur.

for

uL

B

M

C

ana

rJ

RBM

C;

-

tn.

u-ti

I

ir;;i;;"i.;

;;;;

sene_

ration

up

ro

67.55

Mw

will

be

allowed

*iirrou,

any

restriction

so to.ng

as

the

annual

inflow'ls

lot

ress

than752

x 103

.haT

(i.e.,

tt,its

.fi;;;).

ivr,.n

tr,.

annual

inflow

is

less

thanT52'x

10s

h;-i",

tn.'^.ra

in

Trons

No.

R.L.

(F.

)

Ht

of

Emb.fl

'Rrf.

5

155.OO

95

I t80@

88

9

tso.oc

93

rO

t800c

'to5

t2 1800c

t23

TABLE

XVII.I

Details

of

inflow

and outflow

during

1976-77.

Month

Year

1976

Year

1977

Inflow

in

103

ha

m

Outflow

in 103

ha

m

Inflow;n

103

ha

m

Outflow

in

I03

ha

m

Spill-

Power

U.L.B.

way

llouse

M.C.

Spill-

Power

U.L.B.

Total

way

House

M.C.

ll

r0

January

Ferbruary

March

April

May

June

July

August

September

October

November

December

(-)

e.7

(-)

l1.o

(+)

8.6

(+)

6.8

(-)

l.o

(+)re3.2

(+)384.6

(+)538.8

(+)s06.2

(+)

24.3

(+)

43.0

(+)

t.e

73.1

72.4

101.3

r

03.4

87.9

82.9

98.3

470.r

407.9

84.6

59.7

68.5

(-)

4.4

(+)

e.e

(+)

17.6

(+)

e.l

(-)

o.4

(+)16s.0

(

+)18r.7

(+,302.5

G)432.3

(+)

45.e

(+)

22.r

(+)

1e.s

75.9

7t.4

79.6

87.2

89.6

90.6

rM.2

71.8

69.2

99.1

80.8

83.3

Nil

NiI

Nil

Nir

387.8

319.8

NiI

Nil

72.6

7t.9

100.3

102.6

87.3

81.3

96.5

80.8

86.4

82.4

57.1

65.1

0.5

1.0

0.8

t.6

r.6

1.7

1.6

L.7

2.2

2.6

3.4

Nil

Nit

Nil

il9.1

Nil

Nit

Nil

3.6

i9.5

2.7

74.1

2.8 82.4

2.6

89.8

2.8

92.4

l.l

91.7

0.3

104.5

0.9

72.7

1.1

189.4

2.O

101.1

2.O

82.8

2.9

86.2

Note

:

(ll

Monthly

i!flow

is computed

back

from

th€

difference

betwee!

the rcservoir

l€v€ls aqd

record€d

outflows.

(2)

Tl9

(-)

inflow

is

due

ro-.,t-he

-complex

combiration

of the inherent

errors

ofthe res€rvoir capacity curvc turbine

emcrency

curve

and

applicabilily

ofevaboration

data.

PHOTO

10

:

Closed

spillway

gates

and

bye-pass

outlets.

287

PHOTO

lt

:

performance

of

ski_jump

bucket.

'l.i!':r':,

PHOTO

12

:

Fower

house

complete

area

from

downstream.

288

.-,.'.'..-

Indian National Committee on Large Dams. Design and Construction Features of Selected Dams in India

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