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

Подождите немного. Документ загружается.

7.1 The first

step

taken

was

to

off

lead

the

reservoir

through

the

spillway

gates

and then through

the river

sluice

and

the two

penstocks

in the dam,

while

diversion

for

power generation

.continued

at a

peak

level

(as

is feasible

after

the

earthquake).

7.2 A

committee

was

constituted

promptly

to study

the seismic

phenomena

the damages

in

detail,

and

recom

mend'repairs

and strengthen in

g

measures.

Serv ices

of Professer

Dr.

S.

Okamoto

Japan,

Prof. Dr. I.E.

Gubin,

U.S,S.R.,

Dr.

J.B.

Auden,

F.A.O.

(previously

of

Geological

Survey

of

India)

were

obtained

with rhe

assistance

of

UNESCO

and

World

Bank.

Prof.

C.

Tamura

Japa_n, J.

Bellier,

A.

Mayer,

Y. Guyon,

Dr.

Garon

all

of

France

also

visited

and

gave

-valuable

advise.

7.3

Even

before

the

upstream

face

could

be available

for

visual inspection,

under

water

inspection

was

got

carried

out by

divers

in the

zone

corresponding

to

the

downstream face

manifestation

of

wetness.

Where

so

televised

and

detected,

the upstream

face cracks

were

got photographed

by

an

under

water television

camera.

The

results

of such

an inspection

of the up-

stream

face and

the

visible

downstieam

face

of the

dam

can

be seen in

Figure

7.1.

Seetion

VI

tr-

fru:

estig

ation

7.4

Cracks

and

wetness

on the

downstream

face

have

prominently

cgincided

with

the

level

2060

where

there

was

an abrupt

change

in

slope

(see

photos

6.4

&

6.5).

The

spillway

was

free

fromihe'

cracks

on

the dowi-

stream

face.

On

the

upstream

face more

monoliths

manifested

the

cracks

than

on the downstream

face

and

the

zone

of

crack

was

between

elevations

2035 to

2065.

Of

the

7

spillway

blocks

four showed cracks in

tb" upstream

face.

Important

cracks

were

kept

under

observation

through

measurements

and

tell

taies fixed

across

the

crack,

because

of the

numerous

after

shocks.

Minute

longitudinal

cracks

along

the

upstream

top and

downstream

bottom

corners

of

gallerieS

could

b-e ex-

plained

by

stress

concentration

that

occurs

at those

locations.

LI

Upli{t

measurements

showed

ro change

vide

Figure

7.2.

At

all

times

uplifts

downstream

of

the

drainage-

gallery

were

considerably

less

than

the

design

assumptions:

7.6

Cores

taken

from

the

foundation

gallery

indicated

no

separation

between

the

body

of ihe dam

and the

foundation

rock

(Photo

7.1).

?.7

By

1968,

the

temperatures

in the

body

of the

dam

have reached

near

stable

temperatures.

Figure

2.3

Crocks

€xpo)g/

grcrfed

ond

gurflled

UPSTREAM

ELEVATTON.

l.-------

a

DOWNSTREAM

ELEVANON

e Top,of

dom

r

n

r-. trco

F-

Ot/€rflory scclion

c

fbist

Fll

o.

€on'irol

roorn

e.

Sqouq

sfuice

r. F<iundotinn line

c. Groun{ lina

x

Crocks

d

nr

Bl

-**

uT*r

onrv

epoxv

srouretl

F.*

157

2f8o

r

er4o

f

U|

J

&

Y

2 too

2060

2o.2o,

t9g

o

t940

t900'

t860

fg20

60'90

FIGURE

7.2:

Koyna

Dam_Uptift

PHOTO

7.1

:

Core

showing

contact

of

rubbte

pressure

diagrams

M Nos.

22,24

and

25.

illustrates

the.ternperature

contours

of

August

1962,

June

1967

and

Deiember-tbir.

7.8

.D-ue

to power

failure

noocled

to

a

depth

of

abo

he

deflections

was

noticed.

4.25

mm

in

the

overflow

I

mm

in

the

non_overflow

ro

January

l963)

[See

7.10

A

studv

of

the

surface

cracks

on

ground,

the

Iocus

of

epicen_ties

ro.uiioo-]"

relation

to

time

and

by.apprying

fault

pFle

solution,-u--iuuit

rrr.

was

delineated

as running

Nrun

t"

silw,

eliir.r^z.o

and

7.7.

7 -lr

rhe

area around

the

Koyna

lake

and

its

catch-

ment

area

were

again got

aeiially

n-trotograjir.a,

to

enable a

comparative

study

of wrth

the

earlier

aerial

photographs

raken

durin!

ptoleli

p;;P#tir;

srage

with

the

posr-earrhquake

-ooir.

"

b.oi;;I;S-;;"

wenr

through

the

old

and

nerv

aeri"l

-

;;.;-.vr"

"""ia

not

Iocate

arv-

adverse

geological

f;ir;;-

(i;il,

and

fractures)

that

-mi-eht-

ha'e"

been

missed

earrier

or

revealed

larer

after

the

earthquake

uoo-iiio

Jon*

the

line referred

to

in

para

Z.tO^above.

7.12

By

this

time

the

controversy

regarding

earth-

quakes

.tr.iggered

by

man-maoe

reservorrs

received

wide

publicity.

oP.

\

B-r.B%

b,

B'r;

ll5

l'

l"o

lo

f%

I

R.L.

2

|

44.OO

Oolcd:

,6-12-6?

F!

o

9

R:L.2144.

r58

and

foundation

rock.

€cel

2r4C

aAxis

of

ctdn

.R.L2133

50

ztoO

2060

202o

t98()

r940

t900

{8

80

r85O

bob ptpe

80 tzo

t@

16.8

-62

'i'Trt,",;trtott

Feel

2loo

2050

2000

t950

t900

75

.R.L

r990

f

zreo

a

i

allo

o

I

z,oo

L

o

i

2060

o

o

e

q_or"

Une

I

6

4

2

o

K.R

L.

t5-

6-67

2OO

lag

FIGURE

7.3:

Koyna.Dam-Isotherms

monolith

22.

,ul

Auo

6z af

Nov

67

Trme

Scole

FIGURE

7.4

:

Koyna Dam

deflection

chart

M

No. 22.

Nov.

-?

-4

-6

-8

Jon

67

Mor.

67

Apr:

67

Jun

67

Feb

68

Dec.

Jon

67

68

rim

FI

if

I ine

-2

-3

-4

-5

-6

-7

-8

I

nstrumeni

Efevotion M

25

Jon

65t

Time

scole

FIGURE

7.5 :

Koyna

Dam defection

chart

M

No. 25.

E

o

o

rj

o

!,

x

Inlermediole

tevel

t976.57

Elevotirn

M.Zz

Top

sr.rspcnsirn

*.e**+v*

159

Golden

o

Frobisher

8oy

o

Goclh5vn

'f&T

rfy*:si'o"

Coptobin

e

aNo

oAkureyr

Vof entiSlnsber

Durhorn-o-

o

Ox

ford

Kevdo

tPPl

Yc

kutsk

oV

lodivos

tok

O

Shrroki

-td

t

,stei

Kirt

lstonb

hens'

crrnon

oAdisobobo

5

Visokhopotnom

i

.Port

Bto,r

^

Loploto

t

i

{Ppr

/

it

eChonqolo'ne

Foult

pfone

solul

ion

Koyno

eorthquoke

December

lort967

Epicentee

tot. rf

Zz.i

tong.7t'

44.d

FIGURE

7.6

:

Fault

plane

solution,

Koyna

Earthquake,

December

1962.

160

lndc

x

f.

Topogrophic

form lin€s---- --.tJ

2.

Heoved

up

portion--

X

3 Up

lhrown

srde -----------

+

4.

Molor fissrlres

wilh min6r

diogonol irocks

a-E

:

-

4

-3.-'

=

-+-

9n

--L-

=

-zJl<<

FIGURE

7.7

:

Fissures

and

cracks

south

of Koyna

River-

7.13

Those

who supported

such

a

phenomena

based

their

betief

in the coiicidence

of the

tremor

activity

with

the

first

filling

of

the

reservoir

followed

by

a

culminating

Severe

shock

after

some

4 or

5

years

when

ah; lake

g-ot

held

at full

reservoir

level.

It

could

be

and

was

m--ost

probably a

fortutious

coincidence.

The

area

was

not

one

of

sedimentaries

or

of

recent

ages.

It

is

an

old

volcanic

formation

with near

horizontal

lava

flows some

3

to 5

km

thick

and

where

no

adverse

geological faults

or

fractures

could

be detected

either

bEfore

or after

the

earthquake.

It was

difficult

tJ

deduce

structurally

that

a

water

load

of

about

100

structural

imbalance

that

s

earthquake.

When

the

:us

deePer

than

8

km

below

tre difficult

to

exPlain

the

I

action

bY a

water

load

of

100

m.

't.14

The

line of

hot

spring

running

north-south

and

nearly

parallel

to

the Aiabian

Sea coast

were

examined

for

rise

in temperatures,

change

in

chemical

composi-

tion

and

increise

in

outflow.

Nothing

cognizable

was

reported.

7.15

The

(believed)

west coast

fault

in the

Arabian

Sea

was oui

in the

Arabian

some 80 to

100

km

from

the

dam and/or

the

coast.

along

a

West-East

major fault

along

which

Narmada

and Sona

Rivers

are

said to be

flowing.

7.t7

Reference

was

made

to

Bouguer

gravity

anomaly

not

true.'

161

e.*t}t<?

tooo

+

t.r.r.-'1

-lt

(

AFTER

OURESI.IY,

M.N.,I964

I

(

PRO.

NAT.

tNST.

SCt.

tNorArvoL.3oA.NO.5)

v

A

(')

t

oo

?

.?

ta

c H

N

A

)

i

e

v

{^6,

\

s

URMA

,.169Ou(

-

too

;loo

19,E,

Bong

ore

L

N

.a

LAKSHAOWEEP

(lNDlAl

-

.Trivondrum

O

5OOkm

l-l

OCEA

g+o

Boo

EXPLAN

AT

I ON

Sources

of

dofo

l.

Survey

of

Indio

,

Technicol

Rerport No.

lO,

lg55

.

-t953

stotions.

2.Geotogicol

g.rrvey

of Indio

publiehed

ond

unpublislrbd

doto-

5l

stotiohs

3.Anomoly

volues

ot

lt65

elotione conrpufed

of

the

Survey

of Indio.

4.Anonroly

volues

of

439

elof

ione

cornputed

ot

the

Geologicol

Survey

of

Indio.

- .

Contour

intervol lOMgds

tO.OtOOb eot

t

6;l'

lndlcotes

grovity

'Low'

Volues

bosed

on denctty

of 2.679/cm3with

seo

tevet

oE dotum

ore with

references

to the

Internotionot

,

grovity

forrnulo

of

l93O

A A=Profite

discussed

in

fext

FIGURE7.8 :

Bouguer anomaly-Map of

peninsular

India.

162

insight

with

the

structure

and

formations

of the

Archeans

below

the volcanics

(Basalts).

-

.

7.?0.

.Contemporaneously

at Bhakra (more

than

twice

as

high

a dam)

in

.

the youngesr

of

the

geological

sedimentaries

comprising

much

iofter

"r

f"Ji.r

rock

8.1

After

such

a

close

examination

and

study

of

the

structural,_

geological,

and

seismological

datal

and

in

view

of the

continuing.

numerous

deciyiog

ii.;ors

(or

qft.t

shocks)

of

varying

magnitudes.

it"was

aeciAeO

lhat

the

lake

will

be

hElo

at

the

eresr

or tne

spillway

[r^or.

7.5

.

m

(25

fr)

berow

the

FRL]

in

tne monsoons

1968

and

those

that

follow

till

the

long-term

strengthe-

niog

works

arg

completed.

Even

6

A;;;,

certain

short-term

repair

worlis

have

to

be

executedblfore

ttre

Iakes

starts

filling

up

in

1968

monsoon.

8.2

Even

though

more

monoliths

showed

a

crack

on

the

upstream

face

and

a

few

only

on

the

downstream

face,

it could

not

asserted

that

in

no

block

ttre cracting

was

not through

the width

of

the

dam.

Secondly

th;

'

lpstream

face

crack

was

in

general

below

El.

2,066, i.e.,

the

level

of

downstream

crack

except

in

2

or

I

blocks.

The

downward

inclination

from

downstream

face

to

upstream

face

of

the

crack level

was

favourable

and

against

any.

sliding

due

to water

pressure.

Irowever,

it

was

decided

that

before

mbnsoon

196g,

the

cracked

blocks

should

be

stitched

across

the

crack

bv

pre_stressed

cables

as

a short-term

measure

of

repairs

and

safety

I.l.

par.ticular,

this

must

be

completed

in

the

99.p_

monoliths

(excluding

spillway

blocki

tg,

20,21,

22,

23)

where

the

cracks were

noticed

on boih

faces.

The

blocks

selected

were

15,

16, 17,

lg and24,25,

26.

8.3

The second

immediate

iepair

of

grouting

required

lh-.

u-pstream

face

_to

be

gof

.*pos.l

by lo"weririg

the

lake

below the

crack

level

is

soon

as

possible,

to

la.toe

enough

time

on

hand

to

grout

the

craiks with

thermo

setting

resins

(epoxy)

with

suitable

combinations

of

hardners

and

diluants

and

seal

off the

face

with

gunite

for

about

a

depth

of a

metre

above

and belJw

the

crack

over

a mesh

of

reinforcement.

Seetion

Vllf-nopairs

8.4

At

the

Technical

University

of Roorkee

model

studies

on

vibrating

table were

initiated

to see if

we

can

reproduce

the

lracks

that

have

been

noticed

on

the

prototype

qnd

then

appreciate

the

forces at

work

to

D-rmglorth

satisfactory

proposals

for long-term

streng-

thening

of

the

bruisedddm.

^

8.5

This

event

of Koyna

earthquake

received

world

*j9:

publicity.

and

Dr.

Anil

Chopra

and Chakravarty

of

the

university

of california

di-d

commendable

*ori.

on

the

structural

stress

analysis

under

dynamic

loads

as

could

be

framed

from

ihe acceleration

diagrams.

These.

studies

proved

very

helpful

and

were

acknorv-

Iedged

with

gratitude.

8.6

Grouting

:Tle

C.W.p.R.S.,

poona

conducted

experi-

ments

extensively,

on

the

locally

available

epoxy

produ-

cts.

Based

on

these

studies,

the

materials

s6lecied

were

tlo_se

supplied

by Dr.

Beck

and

Co.,

poona.

Dobeckot

505, and

Hardner

771

(parrly

imported)

and

a suitable

reactive

diluant

to

reduce

-viscbsity.

'The

final

mix

adopted

was

109

parts

by weight

of

Dobeckot

505,

plus

49.5

parrs

b.y

weight-of

hirdner

771and

l0

parri

by weight

of reactive

diluant.

_

The

proierties

of

the

grout

mix used

are as in

Table VIII.l.

8.7 The

aim

of

grouting

the

cracks

was

primarily

to restore

adequate

bond

between

the

bodies-

of

con-

crete

separated

by

the

crack

and

thus

re-established

the monolithicity

of the

dam

as far

as epoxy

grout

can

penetrate

from

ihe

faces

;d;;

the

samt

timJseal off

thein-gre-ss

of water

into

the

body

of dam

by the

crack

(in

lake

filled

condition)

and

.auie

uplift

foices.

8.8 Inclined

holes

were

drilled

from

the

face

mostly

by ordinary

pneumatic

jack

hammers,

to

intercept

the

163

--------t'

ra

.+

rn

od

o

o

r+

o

(n

o\

irt

o

o

CA

tr

Fil

la

(,)c)()

€5"

=d

$E

q)

F

lH

o

v,

=

:>,

v

€il

>:g

F

*E

**

E

!)-

o

6E

'.:

rE

$Eg

OeQ

trga

c)

t.!

'a

gb

EgF

c)

.l*

E6

s5

&E

z

o)e

>tr

'E(|)

o3

I,a

lr

()

]9

r-

Er.-

oo

()

F

>r

€

rr

(tl

o.

E

{)

v)

t,

h

x

o.

EI

pe

.o

az

>r

X

o

a

o

v

ll)

(J

G)

k

()

a.

'tr

G)

tr

o

t{

ltt

T,

TH

dto

UI

.tJ

sc

X(g

E.g

-(J

5a

F*

XX

ov

e

.r,

(D=

tF=

o€

89

b

-u2

rbo

9cr

o

.9

a-i

Gl

'la

rrl

bO

(D

.t)

g

6

tr

()

E

o

.t)

ID

=

o

O

-a)

E

El

FO

e

€

rr)

J 9tc;

.6

tf

tfl

.+

(*)

@(a

oo

9

c'i

ct

!tr

(a

F

(a

€A

::tfN

r'.

.<t

\d

ra

o^n

s=s

:

\CE

".i

9+

F!

=

?oQ

-61

o\

oi

d

^l'?

oi

IJP

t\

+

+^@

.d;+

t.r

o

o

lal

oi

s

o

o

cl

t\

(\

o

(\

o\

\o

t-

r,.|

+

aa

o

I

O()

>40

<E

1t

>r

(6

€

o

(q

tt

>r

\al

tt)

GI

.U

t\

ra

G'

rt

?a

ao

rd

E

o

ca

tn

a,

co

ln

(t)

>r

(!

'd

t-

4'

(E

E

tl

o

-=

.lt

tr

o

gl

!

k

()

c:

D

o

€

o

()

q.)

B

L

()

'(,

tr

D

(,

ot)

tr

(s

&

9&

<g

!)

b0

d

ct

&

9&

<g

(u

oo

c

&

!s

<E

(u

oo

tr

e$

<i:

q)

br)

tr

&

l(,

v9

<i:

()

o0

&

i'

c,,

;qo

<i:

()

b0

c'

l()

v9

<i:

q.)

o0

c

&

6e.i

a

F,=

E

*

ol t..

l->E

sE!

z'"8

j€#

-:.

EES

.-

lJal

&6

ot)

(,)

3

p

i

L

(B

E

q)

an

>\

.1,

>.

X

o

o.

EI

.o

az

el

E

u

ot)

JI

an

o

(l)

.g

L

,o

Lr

cg

o

E

"o

(u

io

tr

o

€

I

o0

tr

q,

L

u,

rt

o

OD

E

(|)

.!€

.a6

fEtr

Eg)

o5

El

.A

'E

'o

€o

-61S

b

F{EE

FigGt

F

r-

-tl)

r-l

U, =

i€

I

9bE!

TRO

riet

cE

E

q.)

C=

cl=

6v

(D

r.i

50

l-

()'?

3E

Etr

9

=4

e->

tr

164

crack. The

pattern

and spacing

of

grout

holes

is

as

per

Figure

S.t.

As the

best bond is created

on

dry

iurfacei, warm

compressed

air

was blown

through

the drill

holes,

into the crack

space, to

blow

off

all

dust

and

to dry up any

residual

dampness

in

the

crack.

This cleaning also

hetped

interconnection

of

adjacent

holes

in

the crack.

in

the

seveml

blocks

on

the

upstream

and

downstream

6d.

total

length

of

holes-

drilled

for

grouting

is

535

m.

to

5

kg/cm2

was

as

under

:

TABLE VIII.2

Epoxy

grout

consumption in

crack

on the

upstream

side.

Monolith Crack Grouting

with Grouting

with

No. level

Dry

Drilling

Wet

Drilling

KRL

Quantity

Quantity

pumped

in

the

pumped

in

the

crack

crack

kg

ke

Total

quantity

consumed

in

crack

kg

l0

tl

t2

2060

17.57

2Q6s 33.51

2085

37.84

2060

11.81

2060 33.e5

2050

2050

2062.s0

2063

2Ms

&

2071

2060

7.73

206s

3.56

2O4s

)

2050

)

17.35

2084

J

2050

&

2033

20.16

2054

4r.28

2050

2A40

205s

25.69

2040

7.27

203s

2055

3.95

2055

6.19

2055

2.60

rt.66

12.08

46.93

42.59

1o9.67

16.82

76.76

t6t.34

80.50

i

62.29

l

J

10s.97

36.2r

36.09

10.07

6.79

7.40

29.23

45.s9

84.77

1r.81

76.54

109.67

L6.82

76.76

161.34

80.60

7.75

3.56

79.64

126.r3

77.2r

36.09

10.07

2s.69

r4.00

7.40

3.95

6.r9

2.60

Monolith

26

UIS

26

Dls

18

U/s

18

D/s

19

oPerating

gates

Other

minor

cracks

took

very

grout or

nil.

296

kg

96

kg

50

ke

39.7

kg

32.20

ke

small

quantitY

of

t2

13

t4

l5

r6

17

i8

20

23

24

24

25

26

27

28

29

30

3l

32

33

34

8.11

Prestressed

Cabling

Across

the

Crack

Even

though

grouting

is done

on both

faces

where

rtuJkr

were

v'isib-le,

it was

not

possible

to

assert

that

Total

270.46

823.27

1093.73

Note

:

(1)

Proportion

of Epoxy

grout

'

Hr$;f:,

i3l;tof#;l$;

Diluent

:

l0

Percent

(2)

Maximum

pressure adopted

100

psi'

,

.

l.\

165

M.

Cracks

No.

level

.KRL

Grouting

with

Dry

Drilling

Quantity

pumped

in

the

crack

kg

Grouting

with

Wet

Drillirrg

Quantity

pumped

rn

the

crack

kg

Total

quantity

consumed

in

crack

kg

TABLE

VIII.3

Epoxy

grout

consumption

downstream

side.

grout

restored

the

bond

ry

of

water)

for

a

few

feet

vhere

the first

manifestation

were

on

average

about

more

after

shocks

recorded

June

68)

of

which

17

D

between

magnitude

3.0

;,

exceeded

magnitude

4.0.

A

able

and

some

could

reach

8'12

In

these

circumstances

it

was

decided

rhat

the

cracked

and

deep

monoliths

shoulcl

be

stitched

across

the

crack

suita-bre

uy

preitresseo

cabres

so

that

the

::t:1q1. -body .above

and

belorv

the

craci

u"t

togrtn..

ln

unrson

under

severe

dynamic

forces.

Adjpting

this

method

for,,the

long-teim

.slrengthening

(by

pre_

stressed

cables)

was

ser

aside

b;;;;-riLlroirslv

vertical

holes

over

l2S

m

deep

are

required

and

because

there

were

no

preced.nir'"f

,".h:;;;Jti.rriog

*o+.

(I'Iost

work

in

^

the past;

was

for

depth

60 m

ll 11.*1bour. _Furtherrori

touds p..".#f,"*outd

monoliths

so

cabled

were

,

16,

17,18,

and

24,25

and

VIII.S

and

illustrated

in

8-

13

The

ultimate

strength

of

the

high

tensire

steer

was

to

be

not

less

than

150

kg/m11"2

u"?tj.i pcr-

cent proof

stress.

uniform

erongition

at-iaituri

was

9

2060

11

-do-

12

-do-

13

-do-

14

-do-

15

-do-

15

-do-

16

-do-

17

-do-

18

-do-

25

-do-

26

-do-

27

-do-

29

-do-

Hoist

2065

Wall

-do-

2144

r.80

19.63

40.10

30.97

40.88

10.28

I

17.72

J

92.36

62.85

30.90

22.30

76.49

32.44

8.61

I

t

23.76

7.98

r.80

19.63

40.10

30.97

40.88

28.00

92.36

62.8s

30.90

22.30

75.49

32.44

8.61

23.76

7-98

Total

3t.74

482.33

st4.O7

TABLE

VIII.4

Table

of

properties

of

polyester

compounds.

Sl.

Material

No.

p.ropor-

Viscosity

tion

by

Individual

volume

material

c.P.

(28

C)

Mix

Potlife

Bond

strength

of

bonded

briquets

(p.S.C.)

Cured

in

Water

Cured

in

Air

3

days

J

days

15

days

715

days

days

7

days

l2

ll

l0

I.

French

Polyster

l.

Resin

I00

2.

Catalyst

1.00

3.

Accelerator

1.00

lI.

Indian

Polyster

Hylak

l.

Resin

100

2.

Accelerator

0.2

3.

Catalyst

1.0

400

increased

to

720'in

5

hrs

200 increased

to

350

after

5 hrs

I

)'

400

)

I

|

200

)

More

than

5 hrs,

less

than

24

hrs

More

than

5 hrs,

less

than

24

hrs.

293

to

302

202

to

339

175

to

339

266

to

3ll

26b

-to

448

266

to

384

202

88

to

to

430

r75

166