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

tending

Engineer, Procurement

could

only accept the

lowest

tender.

Cases,

where a tender other than the

lowest

was

proposed

to be

accgpted,

went

lo

a.commit-

tee

consisting

of

Chief Accounts

Qffieer,.

Superintending

Engineer, Procurement

and Superintending

Engineer,

Disposals. Cases

involving

forei-en exchange had to

be

cleared

by

the Gbneral

Manager.

Directorate

of

Inspection

and Control: This.Direc-

torate

was responsible

for

the correct

layout

and

good

quality

of the-work and

1[eir

word was law,

but

where

apy

.6ha1rge

in

a

drawing

or specification igsued by

the

Designs

Office

was

to

'Qe

made,

they had to

get

the

prior

concurrence

of the

Designs

Directorate.

No

work-,

could

be

proceeded

lvith

unless

the

layout

and

quality

o[

ryork

had

been

approygd by

the competent

inspector.

,

l

, .,...

l'

,. :,,

..,

:_l

Labora,tory

:

i

A

.

well-equipped'labbratory was

maintained- at Nangal,

where

physical,

chemical

and

petrological

examination

of,aggiegate-

was

carried

out

and

concrete

mixes

wcre

designed. Samples of concrete

were

constantly

taken from

the

vaqious

batches at the

concrete

batching and

rnixing

plant

and their

strength

was tested

at

;Various

'ages'

in

the

laboratory.

The

d.csign

of

the.put:z,olana

was

also

errolv-ed.,hete. But

for

this

well-equfu2ped

laboratqry,

{l.would:have,

hpen

diffi'

cult

to ensure

uniform

good-

quality

of

work. This

laboratory

functioned

untler

the control

of

Director

of

Inspection

and Control.

Bhakra

Control

Board: Initially

there

were

three

partner

States-Punjab,

Pepsu

and

Rajasthan.

Their

number

was reduced

to

two

after

the

merger

of

Punjab

and

Pepsu in 1956. Finance was

provided

by

the

Centre. It was

felt that

ordinary

procedures

would be

too slciw

to finalise

and

execute

a complicated

project

of the

size

of

Bhakra and a

Control

Board

having

representatives

of

the Centre and

the

participating

States

was

placed

in

technical and

financial

control

of

the

project.'

Governor

of

Punjab,

in

his

'peisonal

capacity,

was

the

Chairman

of the

Board.

Chief

Accounts

Officer

and Chief Engineer,

who

were

not

nrembers, were

invited

to all meetings of

the Board.

Chief Ministers, Finance

and Irrigation and

Power

Ministers

of

Punjab and Rajasthan

were invited

to

important

meetings in

which

questions

of

policy

likely

to

have impact on tlle State administration were

discus-

sed.

Large

delegations

of

financial and other

powers

were

made

to

General Mana-eer

and Chief

Engineers.

These

arrangements

proved

to be

beneficial.

The

ad-

ministrative., control of the

project,remained

with

the

partner

State

"Ggvernmquts.

.,

Emergency

Procedure

:

The Control Board

usually

met

at

intervals of

six

weeks,

but

matters

which

could not

wait

till

the

next meeting of the Board

were

referred

lry

General

Manager,

Bhakra Dam/Chief

E-nginepr"

io

the' Secreta.ry

-of

-t59,Bo'aid.under

emer-

gbncy

pqoceduie.

The

Secretary iftbr taking

the

advice

of Finance Secretary,

Punjab

and Union

Joint Secretary

Finance obtained the orders of

Vice-Chairman

and

communicated- them

1o

General Manager/Chief

Engi-

neer.

.

These orders

were

confirmed at

the

nex,t.

meeting

of

the Control Board'.

Financial Advice, Compilation

and

Internal

Audit

and

Statutory

Audit

of

Accounts

:

Secretary,

Finance,

Punjab

and

Union

Joint

Secretary,

Finance,

were

the

Financial Advisers

"to

&e

prpjecl.

Chief Accounts

Officer,

attached

to

'Punjab

.Fin'ance

Department,

looked

after

compilation

and

internal

audit

of accounts

while

Accountant

General,

Punjab had a

Resident

Deputy

Accountant

General

at Nangal to

attend to

statutory

audit

under his superintendence

and

control.

Public Accgunts

Committee,

Punjab

State

assisted

by

Acdoiintant

-General,

Punjab, ejralhined

the accounts

on behalf

of

the

Legislature.

Bhakra

Board of

Consultants

:

A

Board

of consul-

tants

consisting of Indian and

foreign

experts

was

also

set

up for review'and

advice

on important

technical

matters.

This

met

once or

twice

a

year as

required.

2.I

Layout

of

the Dam

and

Appurtenant

Works

A

number

of

layout

studies

were

made

before

adopting

the

present

scheme.

For-

power

plants,

location-s

both

above

ground and under

ground were

considered.

At

one

time,

an

inclined

spillway

on

the

pattern of the

Hoover

Dam

was

included

in the

layout'

Part

fl-Design

of

the

IDum

und

Appartenant

Works

AU

proposed structures

were

tested

on

-hydraulic

modils

and

unsatisfactory

features

were

eliminated.

Final scheme

ut

.-.tg.d,

it shown

in Figure

5

and

comprises :

(l)'

Two

15.24

m

(50

ft)

diameter

diversion

tunnels,

located

symmetrically

on

each

bank,

with

-

-:

:

upstream

and

downstream

of

coffer

dams'

tzl

225.6

m

(740

fr)

high straight

gravity

concrete

dam

with

maximum

normal

water surt-ace

at

Ei.

515.1

m

MSL

(1,690

ft)

and

the

lop -of

the

dam

at El.

518.2

m MSL

(1,700 ft);

th9

downstream

face

of

the

dam

has

0.8

to

l'0

rtop"

with the-

point

-of

intersection

with

the

axii

at

El.

518.2

m

MSL

(1,700

f0'

The

up-

.tt.ut

face

of

the dam

is

vertical

above

rL

+t

1.48

m

MSL

(1,350

ft)

and

has a

slope

of

0.35

ro

I below

iit.

411.5

m

MSL

(1,350

ft)

[except

where

it

has

been

locally

depressed

to

b,t.

rq+.0

m MSL

(1.292-6

ft) to

accommodate

trashrack

structures].

lt may be

noted

that

the

heel

of

the

dam

extends

into

the

upstream

claystone

stratum

in the

river

portion,

rvhere

it

is

nearest

to

the

axis.

These

concrete

blocks

in

this

stratum

confine

the

claystone

and

transmit

stresses

across

it

into

the

sandstone

member

upstream

of

the claystone

stratum

(Figure 7)'

(3)

Overflow

spillway

-controllqd-by

four

l5'2

mx

t+.S

ttt

(50

it

xqi-S

ft)

radial

gates,

located

in

the ceniral

portion of

the

dam

in

order

to

utilize

the

naiural

river

channel

with

a

hydrau-

.

ii"

io*p

stilling

basin

and

a

T-beam

rein-

'

forcid

Concrete

bridge

in four

spans

across

the

radial

gate

sPillwaY.

(4)Twotierofoutletswitheiglt^outlets.ineach

tier

at

El.

402.3

m

MSL

(1,320

ft)

and-432'8

m

MSL

(1,420

ft)l

through

the.daT

discharge

Oo*o

ttre

face

o'f

the dam

within

the

spillway

Portion-

(5)

Two

power

houses

located

symmetrically^on

'-'

"u"h

bank.

The

left

power

house

houses

five

;i6

of

90

MW

each.-In

the

case

of

the

-

right

p"*t.

house

5

units

of

120

MW

each

are

installed.

2.2

Diversion

Tunnels

The

canyon

being

very

narrow'

about-

80

m

tZli.i-ttl

rvide

at the

riier

bed

level,

the

only

.feasible

;;hil-'for

the diversion

of

the

river

consisted

of

"o"rii."tion

of runnels

through

the

canyon

-walls.

The

two-diversion

tunnels

on

either

side

of the

river

named

;;;RGha

biversion

Tunnel'

and

'Left

Diversion

Tunnel'

*.ti

Tin"O

witb cement

concrete

and

had

l5'2

m

fSO

ltt

inside

finished

diameter

and

were

nearly

0.80

ktn

il"ti

i

toit.)

each

in length.

The

tunnels

were

laid

at

;

,lop"

of

b.OOZOS

(nearly

same

as

the

river

bed

_qlope

ut

itt.i.

locations).

The

estimated

maximum

discharge

caoacitv

ofl

.a"h

tunnel

was

3228-00

cu

m/sec

(t

i+,OOb

cusecs)

with

the

maximum

po_spible.-theoret-

ical

upstream

pond

level

at elevation

393.50

m

(1,291

ft)

above

mean sea

level expected

in

case

of

the

worst

possible

assumed

flood

of

11,043.6

cu

m/sec

(390,000

Lusecs).

Consequently,

the

tunnel

lining

was

given

a

trard,

smooth

finish

io

withstand the

abrasive

action

of

nign

velocity

waters, carrying

heavy

load

of

shingle

l0

and

boulders

and to

keep

the

frictifnal

losses

to

the

minimum.

The tunnels

were

designe{

as non-pressure

conduits

and

lined with

1.2 m

(4

ft)

lthick

cement

con-

crete

on

the

average

and

suitably

reiriforced

with

steel

bars

in

bad

reaches.

purpose.

2.3

Cofftr

Dams

The

main

decision

required

about

these

coffer

dams

(Figure 6)

was

the

fixation

of

{heir

heights'

t

I

$

6

I

h

6

k

cil.

ctJ

lt

clqtfua

tlrofum-,

5lo

5.@

a

lrul

\---l

\

___

fi.IO+OO

\----

-----z-

//,

7x4

I

6

n-12

;\

\-_

.-_u.r-

n-Er=lST_l_,

"r

rrOOl

SaALEWFEE|

DAM

B POWER

PLANT

GENERAL

LAYOUT

!

I

\

)buttrnenl

foundolions

in

sondslone

t

lo

b,

grouted

for

cffcctire

scepoge

cul-off

For dcloils

gee

dwg,

OJ-A-5

B$

tes

ir

,3

.l

't

/'

.t

NOTE,.

Po

rtions

mo

rked

@

;,

pten

odJeent

to lunn e f

P

rdols

lo bc

gunilcd

or

profeclcd

wilh

hcovy rock

PLAN

Anchor

bon

eg'c1C

\

_(.

E

OETAL

OF

REINFORCE ME

NT

(enotcreD

.N

vERrtolL

PLANE)

Prypclrct

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bars

e

t!o'c/c

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a

tt6'ch

choin

26+ao

1to.

l3tOO

7

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PROTECT4ON

OF

DO}VNSTPEAM

NOTE,-

F-rsUlo

grde

mqtcriol

tn

zetvs

SqglFrcnr

rrne rb

Coorsc

lotords

il-

face

of lE

doa.

Ecrn vories front

lo

15'on

lhc

rrght

!5

on

lle

kl

obulme nl.-

)

"'

tt-

Ch

Sond

fiil*tg

Ouwd

roch

I

lhovy

lrce

droinitry

"Ock

ol le

Rock

fillor

21?

rycn

jotofrd

pipe

tZiElA.precorl

eorEralQ

fuk,

Trrt tf

bcnch

in

serp6tunf'th

lo

b

gror.ttcd

thru

lo.deep

hotes

For

dctoitl

tc.

d*gOt-r-s

scnav

A-A

l,a!.d

h

odjust ttdth

*cordiag

lo

tlp rollit'rg

rquircrncnts.

as-1

ANCI'IOPAaE

OETIIL

25O

REOUIPEO

fays

bort

ArlrcAl

ond

I

Ho?taaalol

steol1

F6aqc

ll

vefticot

t/..t

o

t.o'c&

t2tltAnclwop

6lek

ELEUATTO'|

8-8

(*c

oerle

tr

Rc,Nrilceianr)

Qr

P

OPE

l3

51

Bcrn vories

from

lO 15'on lt1s

Ttght

t5'on

ltt,

left

aaulinent

obulne

nl.^

)

...-

Choin

26+80

4-A

Fi.ld

h

odjud

tldrh

acoding

lo

tlp

rolling rquircacnlg.

-.--l'lhrck

gunrte

retolorccd

Ond

./'

olrchofed

abora

ntnl.r wolcr

leve/.

ct.

tt77.0

--LE!ry!-Lt4--

.*eE

0 4Q

.fr F(Cf

lllrll.rrl|J

PLA

X

&lLE

I

t.o

20

t,o

+

FEET

stc?toY

M

*tLE

?'

,

;

,

1..

t---J-J

FccT

qrTea

oEfttlt

BHAKRA DAM

DOWNSTREAM

COFFER

DAM

PLAN, SECTION

8

DET

AILS

Ff

GURE

6

(ol

C/oy

:ore

,o,deep

leyed

/5'

info

ZPu+'hen+

.t"a,

Eloo

€t*

srao

€

o/'Cotsardatn

e1

t

(i

"

-Jt

PL AN

Poor

Sand

Jfonc

rib

b bo

rcnovcd

'.'o,

a'arF

ro'/e.o

Kcyad

tt'thfo

alutmcnt

r

_.f

,klura/Jurrbce

R16HT

72

r,

I _

| --

rot

of coluer

da,

tt.lroaoo

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I

/nt

:

I

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-2

cutliy

t/,

Vafutz/.furtb4

Ell

El /.

/,,

tund

rock /lne

*tginalrimr

hd

5fu!-fl.-i"#:v:^F;Z

'ECTION

4.A

--?---

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of

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t2&,o

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tr'1

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//

ExpLA6l4TtoN

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14,.,',

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a1rqtt

hclc

SttJ Sloae

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

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