BEHAVIOR OF THE DAM OF THE SAYANO-SHUSHENSKAYAHYDROPOWER PLANT BEFORE AND AFTER RECONDITIONING

V. I. Bryzgalov and É. G. Gaziev

Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 4, April 2004, pp. 18 – 21.

After filling of the storage reservoir of the Sayano-Shu-

shenskaya HPP in 1989 it became obvious that the parame-

ters characterizing the condition of the dam exceed the de-

sign values. Horizontal tensile cracks appeared on the pres-

sure face of the dam and the contact in the foundation of the

pressure face was disturbed (Fig. 1). The seepage through the

dam concrete and though the foundation reached 520 and

549 liters�sec, respectively. The absence of bottom sluices

did not permit emptying of the reservoir, and it was neces-

sary to restore the water impermeability at a head of over

200 m. The high level of seepage did not allow the workers

to use traditional grouts for injection. Workers of the HPP to-

gether with specialists of the Lengidroproekt Institute and

representatives of the Soletange Company (France) devel-

oped a new process for reconditioning with the use of epoxy

grouts.

Pilot repair operations on the dam body began in 1995

and continued in 1996. After curing cracks in the body of the

concrete dam, workers of the Sayano-Shushenskaya HPP

continued to recondition the contact between the dam and the

rock bed.

As a result of the reconditioning, seepage through the

body of the dam and the rock bed was reduced by 99.5 and

78%, respectively. Performance of repair works inevitably

affected the behavior of the dam, which follows from the

analysis presented below.

Horizontal radial and tangential displacements of thedam. Horizontal displacements of the dam are measured

with the help of coordinate meters mounted on direct and in-

verse plumbs. The plumbs are mounted in seven control sec-

tions. The zero (reference) point of the horizontal displace-

ments corresponds to the deepest anchor of an inverse plumb

positioned 40 m below the contact between the dam and the

rock bed under the central section (No. 33). The zero (refer-

ence) time is May 4, 1989. The tables of the coordinate me-

ters are oriented in every section and at every level, which

makes it possible to measure radial and tangential displace-

ments directly. The geometrical sum of these displacements

gives the size and direction of the total displacement vector

at the point of measurement.

Diagrams for measuring radial, tangential, and total dis-

placements of the dam crest in sections 10, 33, and 55 and of

Power Technology and Engineering Vol. 38, No. 2, 2004

841570-145X�04�3802-0084 © 2004 Plenum Publishing Corporation

25.0

540

500

386

344

307

112,25

542 0 10 20 25 33 45 55 67

307 – 315

1

2

2

1

a

b

Fig. 1. Tensile cracks in the pressure face of the dam and in the rock bed: a, view on the dam from head race; b, cross section of the dam; 1,

cracks on the pressure face; 2, crack in the rock bed.

the angles of deviation of the vectors of total displacement

from the direction of the radius of the dam are presented in

Fig. 2. These diagrams show that

— radial displacements stabilized virtually fully in

1992, i.e., in the first three years after filling the storage;

— radial displacements increased in 1996, when cracks

in the body of the dam were cured by injection of epoxy

grout (pilot works in sections 23 and 24 started in 1995); af-

ter the repair of the body of the dam finished, radial displace-

ments decreased again;

— new growth in radial displacements began in 1998

due to the beginning of injection of cracks in the bed and in

the abutments;

— in 2002 the radial displacements of the dam began to

decrease;

— the angles of deviation of vectors of total displace-

ment from the direction of the radii remained virtually un-

changed in the entire period of observation since 1989.

Vectors of displacement of the dam crest are presented in

Fig. 3.

Simultaneously, starting with the date of filling of the

storage in 1989, we observed residual irreversible radial, tan-

gential and vertical displacements of the dam, which seem to

be connected with the process of adaptation of the dam to the

rock bed. We understand residual (irreversible) displace-

ments as the displacements preserved in the dam after re-

moval of load. Since the dam is not unloaded fully, we mean

in the given case the “nonreturn” of the dam to the “initial”

position that existed before the application of yearly load

upon filling of the reservoir. The diagram of residual radial

displacements of the crest of the central arm of the dam (sec-

tion 33) is presented in Fig. 4, and the diagram of tangential

displacements of sections 10 and 55 with the corresponding

trend lines is presented in Fig. 5. The trends of these dia-

grams plotted on the basis of polynomials indicate (Fig. 5)

that the tangential displacements have started to damp down

on the left bank (section 10 in the lower part of the diagram).

Vertical displacements of the dam. Vertical displace-

ments of the dam and of the adjoining territories are deter-

mined with respect to the fundamental and operational

groups of checkpoints located in the tailrace of the

Sayano-Shushenskaya hydropower plant (SShHPP) at a dis-

tance of 3 and 1.5 km from the dam. A longitudinal hydraulic

elevation meter locked on to the geodetic network is

Behavior of the Dam of the Sayano-Shushenskaya HPP Before and After Reconditioning 85

Radial displacement of the dam crestof SShHPP

Tangential displacements of the dam crestof SShHPP

Total displacements of the dam crestof SShHPP

Angles of deviation of total displacementsfrom the direction of dam radius

1988

1988

1988

1988

1990

1990

1990

1990

1992

1992

1992

1992

1994

1994

1994

1994

1996

1996

1996

1996

1998

1998

1998

1998

2000

2000

2000

2000

2002

2002

2002

2002

160

160

140

140

120

120

100

100

80

80

60

60

40

40

20

20

0

0

Section 33Section 10Section 55

Section 33Section 10Section 55

Section 33Section 10Section 55

Section 33Section 10Section 55

20

15

10

5

0

– 5

–10

–15

–20

–25

30

20

10

0

–10

–20

–30

–40

Years Years

Years Years

Dis

pla

cem

ents

,m

m

Dis

pla

cem

ents

,m

m

Dis

pla

cem

ents

,m

m

Dis

pla

cem

ents

,m

m

Fig. 2. Diagram of radial, tangential, and total displacements of the crest of the dam in sections 10, 33, and 55 and of angles of deviation of vec-

tors of total displacement from the direction of the radius of the dam.

mounted in the rock bed at a level of 308 m for measuring

vertical displacements. The displacements over the marks of

the hydraulic elevation meter are obtained by subtracting the

running marks from the marks of 1977, i.e., these are re-

garded as “absolute” displacements from the beginning of

observations.

Vertical displacements of the foundation (mark 308 m)

of the first pier of the central section of the dam are presented

in Fig. 6, where the minus sign denotes subsidence and the

86 V. I. Bryzgalov and É. G. Gaziev

Residual radial displacements at headrace level of 500 mSection 33, mark 542 m

1988 1990 1992 1994 1996 1998 2000 2002

70

60

50

40

30

20

10

0

Dis

pla

cem

ents

,m

m

Years

Fig. 4. Residual radial displacements of the crest of the central arm

of the dam from 1989 to 2002.

D = 10.11 mm

D = 35.46 mm= – 29.35°ä

D = 103.55 mm= – 9.33°ä

Dä

= 132.44 mm= – 4.15°

Dä

= 139.03 mm= – 0.8°

Dä

= 116.42 mm= – 0.8°

Dä

= 92.47 mm= + 9.27°

Dä

= 39.17 mm= + 21.3°

29.35

21.3 D = 7.12 mm

55

45

39

33

25

18

10

Fig. 3. Vectors of total horizontal displacements of the dam crest during filling of the storage in 2001.

Tan

gen

tial

dis

pla

cem

ents

,m

m

Right bank

Left bank

20

15

10

5

0

–5

–10

–15

–20

10�19 89� 04� �06 92 09� �23 94 03� �11 97 08� �28 99 02� �13 02

Dates

10-542 10-494 10-467 10-440

55-542 55-494 55-467 55-440

Fig. 5. Tangential displacements of sections 10 and 55 (after the

number of the section follows the level of measurement).

plus sign denotes rising. The data were obtained by geodetic

observation over vertical displacements of control points of

the first pier of section 33 starting from April 18, 1977.

Analysis shows that maximum seasonal vertical dis-

placements have stabilized in the recent years, which cannot

be said about residual vertical displacements that continue to

grow. This means that the upstream piers “rise,” which is re-

flected by their lower subsidence due to the inclination of the

pier toward the headrace, and return to the old position,

though not fully, after drawdown of the reservoir. This in-

complete return results in residual displacement that accu-

mulates. Since 1989 the “nonreturn” of the central arm at the

mark of 344 m has reached 8 mm (Fig. 7). In 2002 the

growth in residual vertical displacements of the dam stabi-

lized.

The growth in accumulated vertical displacements of the

dam can indicate formation of a loosening zone in the rock

bed.

Angles of slope of horizontal sections of the dam. An-

gles of slope of horizontal sections of the dam are measured

by transverse hydraulic elevation meters in dam galleries.

The results of the measurement are given in seconds, and the

minus sign denotes inclination toward the tailrace.

During filling of the storage reservoir the angles increase

due to the inclination of the dam to the tailrace; during

drawdown the angles decrease. Diagrams of the angles of

slope of the central arm of the dam at filled storage are pre-

sented in Fig. 8.

The presence of residual displacements affects the angles

of slope of horizontal sections of the dam, which is illus-

trated by the diagram of Fig. 9. As in the diagram of radial

displacements, we can see that the angles of slope change

markedly over the entire height of the central arm at the be-

ginning of works on crack curing in the body of the dam in

1996 and at the beginning of reconditioning of the founda-

tion of the dam in 1999. In 2002 the angles of slope began for

decrease, which indicates stabilization of the behavior of

the dam.

Behavior of the Dam of the Sayano-Shushenskaya HPP Before and After Reconditioning 87

Wat

erle

vel

sin

rese

rvoir

,m

Vertical displacements, mm

600

550

500

450

400

350

300–30 –25 –20 –15 –10 –5 0

1986

2001

200

2001

1985

1982 198

1978

1977

Fig. 6. Vertical displacements of pier 1 of section 33 from 1977 to

2001.

9

8

7

6

5

4

3

2

1

01988 1990 1992 1994 1996 1998 2000 2002

Years

Dis

pla

cem

ents

,m

m

Fig. 7. Residual vertical displacements of the central arm at a level

of 344 m.

Lev

els,

m

Angles of slope, sec

420

400

380

360

340

320

300–20 –40 –60 –80 –100

1993199419951996199719981999200020012002

Fig. 8. Angles of slope of horizontal sections of the central arm of

the dam at filled storage.

308

322

344

359

386

413

10

5

0

–5

–10

–15

–20

–25

–30

–35

1990 1992 1994 1996 1998 2000 2002

Angle

sof

slope,

sec

Years

Fig. 9. Angles of slope of horizontal sections of the central arm of

the dam at headrace level of 500 m (residual angles of slope).

CONCLUSIONS

1. Curing of cracks performed by a new technology has

decreased seepage through the body of the dam and the rock

bed by 99.5 and 78%, respectively.

2. After injection of epoxy grouts into cracks the growth

in absolute radial, tangential, and vertical displacements be-

gan to stabilize.

3. Diagrams of accumulated residual displacements re-

flect the process of growth in these displacements, which

may be explained by “compaction” of the ground in the abut-

ments of the dam. Growth in the accumulated residual verti-

cal displacements of the dam can indicate formation of a

loosening zone in the rock bed. In 2002 the residual radial

and vertical displacements showed a tendency to stabilize.

This process of “adaptation of the dam to its rock bed” is

sure to be accompanied by redistribution of stresses in the

body of the dam and in the abutments, as a result of which

new conditions are created for interaction within the dam –

bed system.

4. In 2002 the displacements and the angles of slope of

the dam started to decrease, which reflects the beginning of

stabilization of the behavior of the dam.

88 V. I. Bryzgalov and É. G. Gaziev