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

Toe

Weights

Fill

Placement

Progress

'Rip-Rap

The

Beas Dam

reservoir

has

a straight

fetch

of

more

than

24

km._

According

to

American-

Society

of

civil

Engineers,

the

size

of

ihe

individual

stone

for

rip-rap,

against

the

aforesaid

reservoir

fetch with

an

The

proposals

were

:

(a)

Precast

cement

concrete

Hexahedrons

(b)

Soil

Cement

(c)

Stones

in wire

crates

(d)

Hand

packed

rip-rap

Tetrahedrons/

The

provision

of hand

packed

rip-rap,

according

he

approved

design,

required

0.25 million

cu m of

to

the

approved

design,

required

0.25 mil

mof

to

the

approved

design,

required

0.25 million

cu m of

+200

mm

size

boulders. The

procurement

of such

a

colossal quantity

from

the area

in

vicinity

of

the

dam

w_as not

possible

besides

the

problems

of its

storage and

placement.

The

panel

walls

due to

their

enormous

dgpth

too

were

dampering

the

pace

of

work. In

view

of

the field

difficulties

the

design

of rip-rap

was

218

4.

INSTRUMENTATION

_

To

monitor

the

behaviour

of

the

dam,

a

number

of

instruments

have

been

embedded

in

lt,

body

(Figure

7).

These

consist

:

(r')

Piezometers

(a)

Embankment

piezometers

(b)

Foundation

piizometers

(c)

Porous

tube

piezometers

(ii)

Vertical

and

Horizontal

Movement

Devices

(a)

Cross-arms

combined

with

horizontal

movemenr

installation (U.S.B.R.

type)

(b)

Surface

settlement

points

(iii)

Slope

indicators

(iv)

Seismic

instruments

Ins

t

rumentat

io n

O

b

s

er v

at

ion s

(a)

Pone

PnsssunEs

The

embankment-piezometers

(twin

tube

hydraulic

type)

have

been

instalied

at

three

different

rocafions

:

Location

Number

of

Number

of

tips

installed

functioning

Station

22

+

55.5

m

(right

abutment)

Station

18

+

28.8

m

(central

portion)

Station

14

+

32.6

m

(left

abutmenr)

36

L2

3l

t2

37

t4

Fifty-five

piezometers

which

are

functioning

properly

$o*

characteristics

of

good

piezometrii

circuits.

The

remaining

piezomerers-due

t^o

choking/

leakage,

.give_

erratic

leadings.

The

observed poli,

pressyres

in the

piezometers

bre

generally

within

the

permissible

design

limits.

o

t\

=

c

o

t

s6

ON

=-

o=

Eb

Er.

ne,

6=

ib

2

a

Ao

=-

6=

tb

Cf

2s

^t

go

.25

aL

=o

go.

5E

\) r-

lo

E

-o.

l'

6

I

-e8fi

rl

g

B3E

3

O.

NNN

.F

:=o

U(v

e=

c

ar

E

€,

(,

o

a

I

\

=

C

o

)

o

rl,

.z

I

2

e

f

u

or'

()

'E

o

FI

a

t

q)

c)

cl

tu

e

GI

td

&

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fr

I

t\

I

('l

F

I

N

F

e

lnoJrl

passo

JIAO

Jaqol

dnror

.2Ae''

I

uJo9

9:

trl6lg

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Ja^lu

ul

lu

n3

uorlilur

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unurlxouJ

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ur

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3l

.aunc

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I

|||

nt

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uo!ll!u,

ll.0l

ul

'13

lu€urlnqo

|.|

o

(t

o

9

o

-(\'N

uf

llC uolllluJ

ul

lueulasold

luaurasold

llu,(lqluoyrl

39

ll!J

a^llolnirJn?

n

uollllul

ul

219

Nornol

reser

Dcod

.io'oeglg=l&r_

3

Deloil

Rip

rop

70

o

/

tr

SECTION

OF DAM

i-o.25h

PLAN

SHOWING

GROUTING

PATTERN

E

ot

('

F

,|

TYPICAL

SECTION

(Surfoca

grouting

AO7.

of

the

pifched

oreot

!

75

nm to

2OO

mn

moteriot

f

2OOmm

molcriot property

hond

pocked

ond

grouled

DETAIL

-

A

h

7.62m.

f

.

z.6A

m

,{*

z.6Am

,{

7'62m.r-

7-

220

FIGURE

21

: Upstream

slope

rip-rap

and

grouting.

(b)

FouNDArroN

Prszoruerens

The

tips had

been installed

by

drilling

holes to

a

maximum depth

of

24.4

m

and

located

in various

geological

strata which were of concern

from consi-

deration of seepage,

uplift,

etc.

Location

Number

of

Number

of

tips

installed

functioning

satisfac-

torily

Station

22

+

55.5

m

Station

18

+

28.8 m

Station

14

+

32.6

m

Between

station

18

+

59.3

and 18

+

89.8

m

along

clay

shale

band

I A

(b)

HonlzoNrAl

MovrueNr

Internal

horizontal

movement

devices

have

been

installed

as

a

part

of

the

telescoping

vertical

movement

cross-arm

devices B,

C, D,

E,

F

and

G.

Horizontal

movement

of

plates

is

transformed

into vertical

move-

ment

by a linkage

system.

The

observations

of

these devices

so

far

have

revealed

nominal

changes

in

horizontal

strain

during

the

post-construction

period.

(c)

Sunrece

SeTTLEMENT

PorNrs

The

surface

settlement

points,

numbering

lO2,

consisting of

steel

rods

grouted

into

the sloping

surface

of

the

dam have

been

located

at different

elevations

along the

dam

slope

both

on

upstream

and down-

stream.

There

are

in all two

rows

of

such

embank-

ment

measurement points

provided

along

upstrearn

(El.

387.10

and

411.48 m)

and

four rows

along the

downstrearn

slope

(El.

434.95, 411.48,

387-10 and

362.7 |

1356.62

m).

Plates

of size

225

mm

X

75

mm

x

6

mna

for

measuring

settlements

have

also

been installed on

top

of

parapet

wall of dam.

The observations

for the

cumulative settlement

and deflection

on the

surface

settlement

points

have

been

made with

reference'

to

control targets/bench

marks.

These

observations

are within

permissible

limits.

Slope

Indicators

Slope

indicator

installations have been

provided

one

in

the

body

of

the

dam

at

about its maximum

section

to record

displacements within the embank-

ment

and

other

near

the

toe

of the downstream

toe

rveight

to detect horizontal

movement

and

settlement

of

rock below.

The observations

of these

instruments

have

revealed

no

significant

movement so far

during

the

post-construction

period.

(a)

Susrr,tlc AcrIvIrY

Seismic

studies

around Beas

Dam

Project and

Beas-Satluj

Link

Project

are carried out

by

the

India

Meteorological

Department"

Ten

seismological

obser-

vatories

have

been

established in

the area.

The

obser-

vations

recorded

have

not

yet

revealed

any

significant

correlation between the

seismic activitv

and

level

of

water

in

Beas

Dam

reservoir.

(b)

AccELERocRAPHS

Two strong motion

accelerographs, one at the

top

of dam

and

other near its dorvnstream

toe are also

under

installation.

5. CONCRETE

PRODUCTION

AND PLACEMENT

The appurtenant

structures

such

as

diversion

works, spillway,

irrigation outlets,

penstocks

and

8

l1

9

l8

l9

ll

28

53

Observations

of the

piezometers

so

far

indicate

that

the rate

of dissipation

of

pressures

in the

dam

foundation

is relatively

slow than

expected.

(c)

Ponous

TUBE

Prrzousrnns

Vertical

and

Horizontal

Movement

(a)

VrnucAL

Movsl\anNr

height

of

dam.

22r

6.

SPILLWAY

222

7.

ANCHORAGE

For

the

installation

of

these

anchors,

special

bits

for

drilling

-the

holes

and

an

uncler-reiming

tool

for

m-aklng

bulbous

cavities

atthe

end

of

ihese-trot.i

were

designed

and

fabricated

at

the project.

8.

SHAFTS

AND

INTAKE

STRUCTURES

9.

OUTLET

WORKS

.

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224

FIGURE

24:

Completed

intake structures.

were

carried

out

after

stoppage

of

the

flow

through

these

Jiu.irion

tunnetr

ty

lowerin!

stoplogs

at

the

upstream

end.

Ineachtunnel,

two conduits,

each

of

size

2.13

mx

3.20

m,

have

been

provided in

the

gate

reach

with

bell-

mouth

entr,v.

10.

PENSTOCK

\\ORKS

Initially,

penstocks have

been

installed

in

tunnels

pl

and

pj

to-feed

fcur

generating

units

of

Pong

Power

Plant.

Penstock

headers

of

7280

mm

inner

diameter

in each

tunnel

start

from the emergency

gale

upto

mentally.

Fabrication

A

well

equipped

fabrication

yard was

set

up-

at

the

project. The

-

pinstock

headers

of

7280

mm

diameter

*'.ie

fabricated

partly

from

36

mm thick

ASTM

A-285

Grade-C

steel

and

partly

from

28

mm thick

ASTM

4:537

Grade-A

steel. After

cutting

and

marking, the

automatic

welding by submerged arc

process.

Two

sections

of

penstock

liners

were

welded

in

the

shop

10

form

one aisembly

to

a

maximum

length

of 5.8

m.

The

welded

joints

were

tested

through

X-ray

and

ultrasoni-

cally.

Wye,

rhe largest of

its

kirrd

in

Asia,

weighing

about

180

tonnes

was

Fabricated from

ASTIvI

A-537

grade-A

(Figure

25).

r@

225

(o

I

Bend

under

fobricotion

(

b

l Composite

cylinder

being

hydrostoticolly

tested

(

c

) Penstock

bifurcotion

ond

bronches

.being

instolled

FIGURE

25.

Hydrostatic

Testing

The

straight

sections

of

statically

tested

at

150

per

jig

specially

designed

-an

The

combined

bends

wefl

€ones

which

had

already

I

bulkheading

the

ends.

Tl

field

after

compretio-n

by

bulkheading

three

ends

by

umbrella

shaped

burkheads

devefoped

ai

the

proji;.

-'

.Srress

Relieving

.

W-.u9

and penstock

sections

of

thickness

more

than

36

mm

weie

stress

relieved

in

a

rt..tr

relieving

furnace

in

th.e

fabrication

yard.

This

is

-ih.

t"rg.ri

furnace

of

its

type

in

the

couritry.

Painting

After performing

a|I

tests,

the

inside

surface

of

pen-

stock

assemblies

was

thoroughly

"teanid

uy

iand

i0

mm

strip

near

the

edges,

rlied

on

ihe inside

surfice.

ied,

hot

coaltar

enamel

at

Testing

with tbe

help

of

in

order

to

ensure

that the

I

thickness

free

from

Penstock

Erection

The

installation

of

-penstocks

was

carried

out by

unconventional

methodi

by

deploying

a trolley fittei

with

jacks.

Normalty

rhe

jacis

g.it

e'muidded

at6ngwiih

the

pe-nstock

but

the proci:sr,

adopted;b;;;

Duo,

prr-

mitted

r.epeated

use

df

the

iame^jacti.

-rnur

trre

erec-

lited

and

also resulted

in a

of

jacks.

The

concrer ing

J?,1'.T.

ll,"il

ffi

;?i'i;

liner

and

encasing

concr"t..'

fill

cavities

between

the

r1.

PONG

POWER

PLANT

Pong

Power

Plant

is

a

reinforced

concrete

framed

structure

located

in

the

stiiling

basin,

downstream

9!-Re_nstoc'k

tunnels.

It

has

an"iniL-il.0

."pu.lti or

360

MW

-(six.

units

of 60

MW.u.h;,

in"loiing

t*o

units

under

the

extension

proiect.

The

constrriction

operations

for

the

power

plant

commenced

simul-

t3neously

with

the

closure

of

tunnels

pl

and

p2

in

October

1973.

The

main

generating,

equip;nt

has

?q.n

supplied

by

M/s

Bharat"Heavy

Eiectti.uir

Limited,

Bhopal.

The

commissioning

of

the

power

plant

could

not

synchronise

with

the-completion

of

tire dam

b."uur"

of

requirement

of

tunnels

^for

river

diversion.

As

per

conventional

construction

method,

the

civil worki

of

Power

House

have

to

be completed

first

before

taking

completed

first.

This

far

was

also

erected

so

that

months

from

commenc",o",l,

"""riH[i"#

within

39

12'

ruRBrNEs

til,?fBltRtloRs

Ar

PoNG

General

Pong

Power

Station

is

a

surface

station

cons-

tructed

at

rhe

roe

of

Beas

Dam

ut-

Fong.

-TL;

station

it_of

sjngle

lqor

Jype

which

houses

fou]

v.rti.al

shaft

'Francis

Turbines'..

?nd -generators

*iil

a

-jioviriou

for

two

similar

additionar-unirs

rater

on.

Three

pen-

stocks

embedded

in

the

main

dam

bifuicat,

iot"

twe

each

to feed

six

bnits

in pairs.

A

turbine

inlgt

v^afye

is

provided

on

each

penstock

branch,

upstream

of

the

,pirut

caslng.

.Th. _generaror

_barrel

top

is

at

El.

342

m.

Thc

turbine

floor

is

at

Et. 336.10

m.

rurbio.

-pit

lt"es,

is

located

on

the

lefr-

hand

side

lookrng

upstream

of

each

u,nit.

Butterfly.valve

and

its

servomotor

are

located

on

tne

upstream

side.

Turbine

(,

The

turbine

is

of

the

vertical

shaft

.Francis

type,.

Technical

Data

of

Turbine

Rated

output

Speed

Maximum

net-head

Rated

net-head

:

86,200

mhp

(metric);

:

166.7

rpm

:

88.5

m

:

65.5

m

106.4

mg

Rated

discharge

at

rated

head

and output

:

Direction

of

rotation

(viewed

from

above)

:

Clockwise

Maximum

runaway

speed

:

390

rpm

:

4371 mm

Guide

vane,

P.C.D.

,/*++

227

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

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