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F R O M I D E S T O T H E I R R E L I Z T I O N
D I S P E R S E - R E I N F O R C E D C O N C R E T E I N H Y D R O T E C H N I C A L
C O N S T R U C T I O N
Yu. E. Khechinov
U D C 6 9 1 . 3 2 8 : 6 2 1 . 3 1 1 . 2 1 . 0 0 2 . 2
Orien tatio n of the development of Soviet hydropower engi neering toward the further
develop ment of mountain and piedmont regions of the country with their richest hydropow er
resources will mak e it possible, to a considerabl e extent, to avoid a serious technog enic
impact on the environment.
Under groun d layouts of mountain hydrost ations in compariso n with others have obvious
ecological advantages.
This is confirmed by world practice of constructing mounta in hydrostati ons in France,
Italy, Sweden, Japan, Canada, Switzerl and, and other countries.
The solution of technical and economic problems is directly rel ated to reducing the
amount of materials for undergro und structures by involving them in the combined work with
the rock mass and by the wide introduction of new progressi ve materials and technological
schemes.
A prospect ive way to reduce the cost of underground structures is the use of disperse-
reinforc ed conc rete tran sported to the placement site by concrete pumps, concrete spreaders,
and devices for spraying concrete [ i]. For these purposes, the Central Construction Lab-
oratory of the Inguri Hydroelec tric Station Construction Administ ration ori ginall y conducted
a cycle of tests of disperse-rei nforced concretes and mortars, in which as fiber was used
steel wire 25 mm long and 0.3 mm in diameter, whic h corre sponded to the recommende d ratio
s = 80 based on the condition of the combined work of the fiber with concrete [2 ]. The
techn ology of i ntroducing the fiber into the concrete mix was perfected and the effect of
the vibrating process on the uniformity of the distribu tion of fiber in the concrete mass
or sand--cement mortar and character of the change in the strength and defo rmation char-
acteristi cs of the material in relation to disperse reinforcemen t were studied.
During loading of the proportion ed steel wire into the concrete mix and during its
mixing the main shortcoming of such fiber--lumpiness was found, owing to which a non-
unifo rm volume distribut ion of the steel segments of the wire in the mortar component
and hence a scatter of the values both of the strength and deform ation indices of the
concrete occur.
Furthermore, it was established that during vibration, an ordering of the orientatio n
of the fiber dependin g on the type of vibrator occurs. Thus, for example, a study of
sections of disper se-re inforc ed concrete specimens showed that in all cases the distri-
bution of the wire fiber in the volume of a standard cube is nonuniform, and during vibra-
tion on a vibrat ing table or by internal vibrators a tendency toward an arrangemen t of the
fiber parallel to the plane of vibration was noted.
These circumstance s, in our opinion, could substanti ally affect the strength char-
acteris tics of concrete specimens with fraction size 5-20 mm subjected to the tests. A com-
parison of the results of testing dis perse-r einforc ed concrete specimens with the indices
of a standar d unreinfo rced specimen (Table i) did not reveal noticeable correlations bet-
ween an increase of the percent of reinforce ment and bending-ten sile strength, esp eciall y
at an early age.
The tests were conducted by the standard method correspond ing to State Standard GOST
10180-78 and the specimen s of small concrete beams measur ing i00 i00 400 mm intended
for bending- tensil e tests and cubes measurin g i00 i00 I00 mm intended for compressive
tests were st ored in a room of the concrete laboratory at a relative hum idity within 80-95%.
Transl ated f rom Gidrote khniche skoe Stroitel'stvo, No. 9, pp. 41-44, September, 1991.
0 0 1 8 - 8 2 2 0 / 9 1 / 2 5 0 9 - 0 5 7 5 5 1 2 . 5 0 9 1 9 92 P l e n u m P u b l i s h i n g C o r p o r a n i o n 5 7 5
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T A B L E 1
Bending tensile
Fiber stre ngth , Pa, at age,
c~
o f
7 28 180
vohm~e
0
0 , 5
1,0
2 ,1
1,7
1,9
2 ,2
2 .8
2 .7
3 3
2 9
3 9
Compressive strength,
MPa, at ag e, days
7 28 180
7
2,6 26
12,6 22 8 26 ,3
T A B L E 2
Parts of
prisms
divided
vertically
Quantity of I ompressive IDeviation of
steel shav-
ings in part strength of content of
of invest i- specimens, l steel shavings
gated v ol - MP a, t age of I from average,
ume,
g ! 3
days 1
II
Ill
IV
230
275
255
250
12,5
14,5
14,7
15,5
--9 I
9
0.8
- - 1 , 0
T A B L E 3
u~ ~ ~] Strength, MPa
~ I . . . . . I splitting ten- 1
~ i D e n a i n g t e n s i l e _
~'~ oi _ _ I si at age,
>an age, da s
~ Y I days
compressive
at ag e, days
0 : 2 . 1
0 .5 2 ,2
1
1,3
1 5 1 ,7
2
3 3,1
2 ,2 2 ,7
2 .5 3 ,1
2 ,2 3 ,2
2 ,3 3 .5
3 .2 4 ,1
4 ,2 4 ,4
1
1,2
1,2 1,4
0 ,8 0 ,9
0,8 1,1
1,6 1.9
2 ,7 2 .7
7 1 7 . 5 1 2 5 . 8
1 .8 [ m 5 [ 2 4 2
1 7 [ 1 4 L 1 8 5
1 8 114 1119 2
2.4 123 129
28
28 ,5
28
28 ,5
28 .6
37
44
T A B L E 4
Material of
specimens
Weight of
specimen, g
before :after
test test
i ~ C o e f f . o f
~ ~ relative
~ ~u~ wa te r
9 ~ I ' - ~
wear re-
-~ > o sistance
Granite
Concrete
Disperse-rein-
forced con-
crete
2485
11 729
11 545
2470
l! 89!
11 525
i s
38
20 8 ,2
1
0 ,35
0 ,6 8
I t w a s n o t e d t h a t o n a l l t e s t e d s p e c i m e n s , n o t a b r e a k b u t r a t h e r a d r a w i n g - o u t o f t h e
e n d s o f t h e w i r e f r o m t h e h a r d e n e d m o r t a r c a u s e d b y i t s i n s i g n i f i c a n t c o h e s i o n w i t h t h e
s m o o t h s u r f a c e o f t h e r e i n f o r c e m e n t o c c u r r e d .
A r t i f i c i a l l y c a l i b r a t e d b a r s a r e u s e d a b r o a d t o i n c r e a s e c o h e s i o n o f t h e w i r e w i t h t h e
m o r t a r c o m p o n e n t s o f c o n c r e t e , o r t h e g e o m e t r y o f t h e w i r e i s c h a n g e d ( w i t h b e n t e n d s , Z -
s h a p e d , w i t h f l a t t e n e d e n d s , e t c .) , w h i c h r e q u i r e s s p e c i a l t e c h n o l o g y o f m a n u f a c t u r i n g t h e
f i b e r o r i t s t r e a t m e n t a n d , i n t u r n , l e a d s t o a s h a r p i n c r e a s e o f it s c o s t , b u t d o e s n o t
e l i m i n a t e t h e p r o p e r t i e s o f l u m p i n e s s [ i, 2 ].
S h a v i n g s , b e i n g t h e w a s t e o f m e t a l - m a c h i n i n g e n t e r p r i s e s , w e r e t e s t e d i n t h e s e a r c h
f o r m o r e e c o n o m i c a l s o l u t i on s . S h a v i n g s o b t a i n e d d u r i n g m i l l i n g o f m e t a l , u n l i k e s t e e l
w i r e f i b e r , h a v e f l o w a b i l i t y a n d d o n o t h a v e a n y s i g n s o f l u m p i n e s s o r s t i c k i n g t o g e t h e r .
5 7 6
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M P a
#5
4 0 . .
35
30;
o
10
E
/ " / 7 d a y s
o
O r 5 f ,O r f ~ O 2 f h
~ i / ' t 7 t i _ j
0 $Y 76'
a
15 6 i~Yf
kg
M P a
5 ~
qTO ~
45 ~ _
2~5 ~ i 7 days
2 ~ J days
1 5
0 5
o 0 , 5 1 , o 1 , 5 z , o z , 5
i
3~ 78 7 56 79 f k g
b
F i g , i. D e p e n d e n c e o f t h e c o m p r e s s i v e ( a ) a n d b e n d i n g
t e n s i l e ( b) s t r e n g t h a t v a r i o u s a g e s o n t he c o n t e n ~ o f
s t e e l s h a v i n g s .
T h e p a r a m e t e r s ( a r b i t r a r y d i a m e t e r ) o f s h a v i n g s d e p e n d o n t h e t y p e of m i l l i n g m a c h i n e
a n d c h a r a c t e r o f m a c h i n i n g t h e p a r t s a n d c a n be s e l e c t e d a c c o r d i n g t o s i z e s t o f i t t h e
c o n d i t i o n s o f t r a n s p o r t i n g t h e m a t e r i a l b y p i p e l i n e f r o m t he r at i o
D / d = 2 . 5 - 3 ,
w h e r e D i s t h e d i a m e t e r o f t h e c o n c r e t e - c o n v e y i n g p i p e; d is t h e a r b i t r a r y d i a m e t e r o f t h e
s h a v i n g s .
I n a d d i t i o n t o e s t a b l i s h i n g t h e a b s e n c e o f l u mp i n e s s , w h i c h t o a c o n s i d e r a b l e e x t e n t
p r o v i d e d a u n i f o r m d i s t r i b u t i o n o f s h a v i n g s i n t h e c o n c r e t e m i x , e x p e r i m e n t s w e r e c o n d u c t e d
t o d e t e r m i n e t h e e f f e c t o f v i b r a t i o n o n s e g r e g a t i o n ( s i n k i n g ) o f s h a v i n g s i n t h e f r e s h l y
p l a c e d c o n c r e t e m i x .
T h e m e t h o d o f i n v e s t i g a t i o n c o n s i s t e d i n t h e f o ll o w i n g : t h e p r e p a r e d a n d t h o r o u g h l y
m i x e d d i s p e r s e - r e i n f o r c e d c e m e n t - - s a n d m o r t a r w i t h a c o n e s l u m p of 4 c m w a s p l a c e d i n a
s t a n d a r d m o l d f o r i 0 0 x i 0 0 x 4 0 0 - m m p r i s m s p e c i m e n s . T h e n t h e m o l d w a s c l o s e d o n t o p
b y a m e t a l c o v e r a n d p l a c e d i n a v e r t i c a l p o s i t i o n o n a v i b r a t i n g t a b l e. A f t e r v i b r a t i n g
t h e s p e c i m e n s f o r 1 2 0 s e c , c o r r e s p o n d i n g i n t i m e t o n o r m a l w o r k i n g o f c on c r e t e , i n o n e of
t h e b a t c h e s ( t h r e e p r i s m s ) t h e m i x f r e s h l y p l a c e d i n t h e m o l d w a s d i v i d e d i n t o f ou r e q u a l
p a r t s , i . e ., s i z e o f t h e s t a n d a r d i 0 0 I 0 0 1 0 0 - m m c u b e , e a c h o f w h i c h w a s s u b j e c t e d t o
w e t s c r e e n i n g w i t h s e p a r a t i o n o f t h e s h a v i n g s t o d e t e r m i n e i t s w e i g h t c o n t e n t a f t e r t h o r o u g h
w a s h i n g .
T h e a v e r a g e r e s u l t s o b t a i n e d ( T a b l e 2 ) c o n f i r m e d t h e v i r t u a l a b s e n c e o f s e g r e g a t i o n
o f th e m e t a l s h a v i n g s i n t h e m o r t a r m a s s d u r i n g v i b r a t i o n o n t h e t a b le .
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M P a ~ 0 ~
b
? If f0
i
days
Fig. 2. Grap h of the depe nden ce of the modu lus
o f e l a s t i c i t y o f u n r e i n f o r c e d ( i) a n d d i s p e r s e -
r e i n f o r c e d ( 2) c o n c r e t e s a t v a r i o u s a g e s o f t h e
specimens.
c m
3O
fO
r
I / /
I
I
K
0 f ~ 6 8 fO f2 / 18
Width of working, m
Fig. 3. Calc ulat ed data of the thick ness of the coati ng of
t h e u n r e i n f o r c e d ( d a s h e d l i n e) a n d d i s p e r s e - r e i n f o r c e d
( s o l id l i n e) g u n i t e s f o r a d i f f e r e n t w i d t h o f th e w o r k i n g
and degree of fractu ring of the rocks K.
T h e s e c o n d b a t c h o f t h r e e p r i s m s p e c i m e n s a f t e r 3 d a y s w e r e s a w e d i n t o s t a n d a r d c u b e s
a n d s u b j e c t e d t o c o m p r e s s i o n t e s t i n g, t h e r e s u l t s o f w h i c h a l s o i n s i g n i f i c a n t l y d i f f e r
from the avera ge values.
T h e a b s e n c e o f s e g r e g a t i o n o f s te e l s h a v i n g s d u r i n g v i b r a t i o n i s r e l a t e d t o t h e
c h a r a c t e r i s t i c s h a p e o f a s h a v i n g a n d t o it s c o n s i d e r a b l e s p e c i f i c s u r f a c e , n o t a l l o w i n g
it to sink into the morta r mass.
I n o r d e r t o e l i m i n a t e t h e e f f e c t o n t he s t r e n g t h i n d i c e s o f t h e d i s p e r s e - r e i n f o r c e d
c o n c r e t e o f th e a g g r e g a t e f r a c t i o n s t h a t c a u s e d s c a t t e r i n g o f t he v a l u e s i n t h e p r e c e d i n g
e x p e r i m e n t a l s e r i e s w i t h w i r e f i b er , f u r t h e r t e s t s w e r e c o n d u c t e d o n s p e c i m e n s m a d e f r o m
c e m e n t -- s a n d m o r t a r s ( s a n d w i t h f i n e n e s s m o d u l u s M f = 3 . 5) a n d r e i n f o r c e d w i t h s t e e l
shavings.
A c e m e n t - - s a nd m o r t a r M - 3 0 0 w i t h a c e m e n t c o n t e n t o f 6 8 5 k g / m ~ a n d w i t h a c o n e s l u m p
of 4 cm was taken as the initial one. The results of testing the cement--sand spec imens
w i t h v a r i o u s c o n t e n t s o f s t e e l s h a v i n g s a r e g i v e n i n T a b l e 3 . T h e b e n d i n g - a n d s p l i t t i n g -
t e n s i l e t e s t s o f s p e c i m e n s w i t h a l o w c on t e n t o f s h a v i n g s ( w i t h i n 0 . 5 - 1 . 5 ) d i d n o t r e v e a l
a n y e x c e s s o f t h e v a l u e s o f th e s e i n d i c e s i n c o m p a r i s o n w i t h s t a n d a r d s p e c i m e n s .
H o w e v e r , w i t h a n i n c r e a s e o f t he c o n t e n t o f s h a v i n g s ( w i t h i n 2 - 3 ) t h e b e n d i n g - t e n s i l e
s t r e n g t h ( w h i c h i s e x c e p t i o n a l l y i m p o r t a n t f o r u n d e r g r o u n d s u p p o r t s t r u c t u r e s ) o f t h e s p e c i -
m e n s a t a n e a r l y a g e in c o m p a r i s o n w i t h t h e u n r e i n f o r c e d i n c r e a s e s b y 5 0 - 8 0 a n d t h e s p l i t -
t i n g - t e n s i l e s t r e n g t h b y 1 2 5 - 17 5 . T h e v a l u e s o f t h e s e i n d i c e s f o r s p e c i m e n s a t a n a g e o f
2 8 d a y s e q u a l i z e , b u t n e v e r t h e l e s s t h e be n d i n g - a n d s p l i t t i n g - t e n s i l e s t r e n g t h o f t h e
r e i n f o r c e d s p e c i m e n s a r e h i g h e r t h a n t h o s e o f t h e u n r e i n f o r c e d b y r e s p e c t i v e l y 4 0 an d 70 .
A s t he t e s t r e s u l t s s h o w e d , t h e c o n t e n t o f s te e l s h a v i n g s a f f e c t s a l s o t h e c o m p r e s s i v e
s t r e n g t h o f t h e s p e c i me n s . W h e n t h e f i b e r c o n t e n t i s m o r e t h a n 1 . 5 , t h e c o m p r e s s i v e
s t r e n g t h o f t h e c o n c r e t e s p e c i m e n s r e i n f o r c e d w i t h s t e e l s h a v i n g s i n c r e a s e s m a r k e d l y w i t h
age (Fig. I). The same such picture is observ ed also in the bending ten sile test of the
specimens.
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TABLE 5
Bending tensile strength, M~a, at age, days
specimens reinforced wi th mes h
specimens reinforced with
steel shavings
scheme scheme 2 scheme 3 scheme I
1,75 i 2,9 3,3
7 28
2 S 3 5
~ ~ 7 6 I
3 ] 7
28
1,9 2,2 2,4
3 7 28
4 05
It is nec ess ary to note the scatter of the values of the test results, which, in our
opinion, can be explained mainly by the inhomogeneity of the steel shavings with respect
to its size, shape, and quant ity in the test specimens. The results can be cons ider ably
distor ted in the case of using oiled shavings, a decrease of which will be observed at
early test times of the specimens.
Corros ion resist ance tests of the specimens reinforced with steel shavings were also
conducted . For this purpose, sp ecimen s of stand ard i00 I00 100-mm cubes were placed
for long storage in a moist air environment. Afte r 2-3 years of stora ge no signs of
corrosi on were found on sections of specimens of the dispers e-reinf orced concrete, with
except ion of those shavings which contacted the surface of the faces of the specimens.
A visual inspecti on and measuremen ts conf irmed that the penetrati on of rust inward
did not exce ed 1.5-2 mm, and the embed ded part of the shavings on the section, as all the
others, had a pure steel luster.
Tests of the deformation properties of the dispers e-reinf orced concretes showed that
their specime ns have values of the modulus of elasticity reduced (in particular, at an
early age) by as much as 30 in comparison with unrein forced specimens, which has important
signifi cance for yielding of supports constru cted from them (Fig. 2).
Shrin kage deformati ons were determined by the known method of the Leningrad Instit ute
of Railroa d Transpor tation Engineers; according to the test results the unreinf orced speci-
mens had the maximum defo rmations (0.275 mm/m) and the dispers e-rein forced concrete speci-
mens had the minimu m (less than 0.200 mm/m). This is explained by the presence in them of
a dispers e skeleton resisting deformations due to the unifor m spatial distri bution of steel
shavings in the mortar mass.
The effect of steel shavings on the occurrence of shrin kage cracks was studied on
tablet specimens. Almost radial cracks visible to the unaided eye appeared in all specimens
not co ntai ning shaving s at the end of 28 days.
Cracks were not observed in the specimens reinforced wit h steel shavings even during
3 years.
Furthermore, the water wear resistance of the specimens was invest igated to determine
the life of disperse-r einfor ced concretes in the event they are used in conveying and dis-
charg e tunnels, ope n spillways, and canals.
The water wear resistance of concrete, estimated by the coefficient of relative wear
resist ance equal to the ratio of the loss of the volume of a standard granite specimen to
loss of the volume of concrete from the effect of a wate r jet, was chec ked on a GAI-I
device accordin g to the method develope d at the Georgia n Scient ific-Re search Institute of
Power and Hydrauli c Structures. It is seen from the experime ntal results that the wear
resista nce of the disperse-rein forced concrete is almost twice greater than that of the
unrei nforc ed (Table 4).
Bending tensile tests of 200 400 80-mm concrete slabs reinforced with a 2.5-mm-dia-
meter steel mesh with a 50 50-mm mesh size were carried out to substantiat e the possibil ity
of using dispers e-reinf orced gunite for supporting walls instead of gunite on a steel mesh
(Table 5).
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T h e a d o p t e d s c h e m e s o f t he a r r a n g e m e n t o f t h e st e e l m e s h i n t h e t e s t s l a b s w e r e d i c t a t e d
b y i ts a c t u a l p o s i t i o n r e l a t i v e t o t he u n e v e n s u r f a c e o f t he r o c k w o r k i n g c o v e r e d w i t h a
layer of gunite, the thickne ss of which for temp orary support is usua lly with in 6-10 cm.
A c o m p a r i s o n o f t h e re s u l t s o f t e s t in g s p e c i m e n s o f s l a b s r e i n f o r c e d w i t h a 3 % c o n t e n t
of steel shav ings r eveale d their increase d l oad-be aring capa city by 5% (3 days), 13% (7 days),
a n d 1 6 % ( 2 8 d a y s ) i n c o m p a r i s o n w i t h s p e c i m e n s r e i n f o r c e d b y a m e s h e v e n w i t h i t s m o s t
favor able ar range ment in the exten ded zone (Table 5, scheme 3).
T o s tu d y t h e t e c h n o l o g i c a l p o s s i b i l i t i e s o f t h e p r o c e s s o f a p p l y i n g d i s p e r s e - r e i n f o r c e d
g u n i t e, e x p e r i m e n t a l w o r k s w e r e c a r r i e d o u t o n t h e a p p l i c a t i o n o f g u n i t e r e i n f o r c e d w i t h
steel shavi ngs in the roof part of the No. 2 appro ach adit to the unde rgro und mach ine hall
o f th e K h u d o n i h y d r o s t a t i o n a n d o n a s t r e t c h o f t h e r i g h t - b a n k s l o p e o n t h e u p s t r e a m e l e v a -
tions of the abutment of an arch dam [3].
N o t e c h n o l o g i c a l p r o b l e m s o c c u r r e d d u r i n g a p p l i c a t i o n o f t h e g u n i t e r e i n f o r c e d w i t h
s t e e l s h a v i n g s b y t h e B M- 6 8 m a c h i n e ; t h e d r y m i x w i t h s t e e l s h a v i n g s u n i m p e d e d l y m o v e d
t h r o u g h a r u b b e r h o s e u p to 5 0 m l o n g w i t h o u t c r e a t i n g p l u g s a n d n o t i c e a b l e w e a r o f t h e
hoses.
T h e t h i c k n e s s o f t h e l a y e r a p p l i e d o n t h e e x p e r i m e n t a l s t r e t c h e s a t o n e ti m e w a s
2.5-3 cm, and in places with an uneve n surfa ce (in depre ssion s) was inc rease d to 5-6 cm
witho ut any signs of peelin g off of the fresh ly placed layer. A decr ease of rebound
was noted, w hich did not exceed 10-15% from the walls and not more t han 20% from the
roof, and the propo rtion of shavin gs in the rebound mass was insignifica nt.
O p t i m a l c o m p o s i t i o n s o f d i s p e r s e - r e i n f o r c e d c o n c r e t e a n d g u n i t e w i t h t h e u s e of
s t e e l s h a v i n g s w e r e d e v e l o p e d o n t he b a s i s o f l a b o r a t o r y a n d f i e l d t e s t s a t t h e C e n t r a l
C o n s t r u c t i o n L a b o r a t o r y o f t h e I n g u r i H y d r o e l e c t r i c S t a t i o n C o n s t r u c t i o n A d m i n i s t r a t i o n . *
T o s u b s t a n t i a t e t h e p o s s i b i l i t y o f u s i n g t h e d i s p e r s e - r e i n f o r c e d m a t e r i a l p r o p o s e d
b y t h e b u i l d e r s i n t h e u n d e r g r o u n d w o r k i n g s o f t h e K h u d o n i h y d r o s t a t i o n f o r s u p p o r t i n g
the walls of the machi ne hall an d room of the guard gates, as well as a perm anen t lining
i n t h e a p p r o a c h t u n n e l t o t h e g u a r d g a t e s , t h e n e c e s s a r y c a l c u l a t i o n s w e r e p e r f o r m e d o n
a c o m p u t e r b y d e s i g n e r s o f t h e T b i l i s i b r a n c h o f t he A l l - U n i o n P l a n n i n g , S u r v e y i n g , a n d
S c i e n t i f i c - R e s e a r c h I n s t i t u t e . * *
T h e r e s u l ts o f c a l c u l a t i n g t h e t h i c k n e s s o f t h e g u n i t e a n d d i s p e r s e - r e i n f o r c e d
g u n i t e l i n i n g i n c o n f o r m i t y w i t h t h e D e p a r t m e n t a l B u i l d i n g C o d e s V S N 4 9 - 8 6 o f t h e U S S R
M i n i s t r y o f P o w e r a n d E l e c t r i f i c a t i o n D e s i g n of t e m p o r a r y s u p p o r t o f h y d r a u l i c t u n n e l s
f o r c o n d i t i o n s o f r o c k c o r r e s p o n d i n g t o a s t r e n g t h c o e f f i c i e n t f s t = i0 f or t h e i r v a r i o u s
f r a c t u r i n g , f r o m s li g h t l y f r a c t u r e d K l, m o d e r a t e l y K 2, t o s e v e r e l y f r a c t u r e d K 3 , a r e
give n in Fig. 3.
A s f o l l o w s f r o m t h e c a l c u l a t e d d e p e n d e n c e s , t h e r a n g e o f u s e o f d i s p e r s e - r e i n f o r c e d
g u n i t e i n c o m p a r i s o n w i t h u n r e i n f o r c e d i s c o n s i d e r a b l y w i d e r . F o r e x a m p l e , o n t h e b a s i s
o f t h e t e c h n o l o g i c a l c o n d i t i o n s o f a p p l y i n g a g u n i t e l i n i n g w i t h a t h i c k n e s s o f 20 cm ,
t h i s r a n g e a p p l i e s t o s l i g h t l y a n d m o d e r a t e l y f r a c t u r e d r o c k s w i t h f s t = i0 w i t h i n l i m i t s
o f t h e w i d t h o f u n d e r g r o u n d w o r k i n g s f r o m 4 t o 1 2- 1 4 m . I n s e v e r e l y f r a c t u r e d r o c k s
t h i s l i m i t f o r d i s p e r s e - r e i n f o r c e d g u n i t e i s c o n f i n e d t o w o r k i n g s w i t h a w i d t h u p t o 7 m .
A c o m p u t e r c a l c u l a t i o n m a d e a c c o r d i n g t o V S N 4 9 - 8 6 s h o w e d a n o n c o r r e s p o n d e n c e t o t h e
g e n e r a l l y a c c e p t e d n o t i o n a b o u t r o c k p r e s s u r e a n d a s s i g n m e n t o f t h e l e n g t h o f t h e r o c k
bolts, as a result of which, for an unde rgro und work ing wi th widt h B = const the load on
t h e s u p p o r t a n d h e n c e t h e t h i c k n e s s o f t he l i n i n g a n d l e n g t h o f t h e r o c k b o l t r e m a i n c o n -
s t a n t w i t h i n c r e a s e o f t h e s t r e n g t h c o e f f i c i e n t o f th e r o c k a t a n e q u a l d e g r e e o f i t s
fractur ing, and when fst = 8 and more they even increase. This first of all pertai ns to
a d e t e r m i n a t i o n o f t h e d e p t h o f th e d i s t u r b e d z o n e hq a t th e s t a g e o f p r e l i m i n a r y c a l c u l a -
t i o n s , w h i c h , a s f ol l o w s f r o m V S N 4 9 - 86 , d o e s n o t d e p e n d o n t h e s t r e n g t h a n d d e f o r m a t i o n
c h a r a c t e r i s t i c s o f th e r oc k s , w h i c h d o e s n o t c o n f o r m t o r e a l i t y .
T h e r e s u l t s o f t h e i n v e s t i g a t i o n s m a d e i t p o s s i b l e t o j u d g e a l s o t h e h i g h e c o n o m y o f
u s i n g d i s p e r s e - r e i n f o r c e d g u n i t e .
*Under the dir ection of A. I. Dane liya and R. V. Pa rtsvaniy a.
**Di rect or A. A. Babalyan.
580
-
8/10/2019 Power Technology and Engineering Volume 25 Issue 9 1991 [Doi 10.1007%2Fbf01836484] Yu. E. Khechinov -- Dis
7/7
T h us , f o r ex a m p le , t h e e c o n o m y o f l a b o r e x p e n d i t u r e s w h e n o r d i n a r y g u n i t e o n a m e s h
i s r e p l a c e d b y d i s p e r s e - r e i n f o r c e d g u n i t e p e r i l 0 0 m 2 s u p p o r t e d s u r f a c e i s m o r e t h a n 3 0 0
m a n - h .
F o r a c o s t o f m e t a l s h a v i n g s e q u a l t o t h e c o s t o f m e t a l s c r a p ( 2 8 - 3 5 r u b l e s p e r t o n ) ,
t h e s a v i n gs f r o m u s i n g d i s p e r s e - r e i n f o r c e d g u n i t e i n c o m p a r i s o n w i t h g u n i t e o n a m e s h
r e a c h e s 1 4 0 0 r u b l e s p e r I 0 0 m 2 o f c o a t i n g [ 3] .
T h e r e s u l t s o f t h e i n v e s t i g a t i o n s a n d c a l c u l a t i o n s p e r m i t t e d p r o p o s i n g a s t r u c t u re
o f d i s p e r s e - r e i n f o r c e d g u n i t e w i t h a t h i c k n e s s o f I 0 cm i n c o m b i n a t i o n w i t h d e e p r o ck b o l t s
f o r s u p p o r t i n g t h e w a l l s o f t h e u n d e r g r o u n d m a c h i n e h a l l o f th e K h u d o n i h y d r o s t a t i o n i n s t e a d
o f r e i n f o r c e d - c o n c r e t e w a l l s w i t h a d e s i g n t h i c k n e s s o f 4 0 c m, a n d a l s o as a p e r m a n e n t l i n i n g
i n t h e a p p r o a c h t u n n e l t o t h e g u a r d g a t e .
T h e s e p r o p o s a l s w e r e n o t r e a l i z e d o w i n g t o t h e d e c i s i o n i n 1 9 8 9 to s t op t h e c o n s t r u c -
t i o n o f t h e K h u d o n i h y d r o s t a t i o n .
T h e w i d e u s e o f d i s p e r s e r e i n f o r c e m e n t * i n u n d e r g r o u n d s t r u c t u r e s , w a t e r - c o n v e y i n g
a n d d i s c h a r g e s t r u c t u r e s , a s w e l l a s in t h i n - w a l l e d c r a c k - r e s i s t a n t s t r u c t u r e s a n d i n
g r o u t i n g j o i n t s w o u l d m a k e i t p o s s i b l e t o c o n s i d e r a b l y r e d u c e t h e c o s t o f c o n c r e t e
s t r u c t u r e s a n d l a b or i n t e n s i t y o f t he w o r k s, p r o v i d i n g a t th e s a m e t i me t e c h n o l o g i c a l
e f f i c i e n c y o f c o n s t r u c t i o n a n d h i g h r e l i a b i l i t y o f o p e r a t i n g t h e c o n c r e t e s t r u c t ur e s .
T h e s p e c i m en s a n d m a t e r i a l s o n d i s p e r s e - r e i n f o r c e d c o n c r e t e a n d g u n i t e p r e s e n t e d f o r
c o m p e t i t i o n w e r e a w a r d e d t h e S i l v e r M e d a l o f t he U S S R E x h i b i t i o n o f E c on o m i c A c h i e v e m e n t s
in 1990.
i
2.
3.
L I T E R A T U R E C I T E D
O . M . G e t m a n e n k o , U s e o f s t e e l f i b e r - r e i n f o r c e d c o n c r e t e in c o n s t r u c t i o n , ~ k s p.
Inf. VNIIS. Stroit el. Mater. Izd., No. 9 (1982).
G . T . M i k e l a d z e , Y u . E . K h e c h i n o v , a n d R . V . P a r t s v a n i y a , D i s p e r s e r e i n f o r c e m e n t o f
s m a l l - f r a c t i o n c o n c r e t e s a n d m o r t a r s , E n e r g . S t r o i t . , No . 6 ( 1 9 8 7 ).
Y u . E . K h e c h i n o v a n d R . V . P a r t s v a n i y a , D i s p e r s e - r e i n f o r c e d g u n i t e fo r u n d e r g r o u n d
s t r u c t u r e s of t h e K h u d o n i h y d r o e l e c t r i c s t a t i o n, I n f o r m e n e r g o S o o r u z h . G i d r o e l e k t r o -
stantsi i, No. 3 (1987).
* A d d i t i o n a l i n f o r m a t i o n a b o u t t h e p r o p e r t i e s o f d i s p e r s e - r e i n f o r c e d c o n c r e t es , o p t i m a l c o m-
p o s i t i o n s, a n d r e c o m m e n d a t i o n s o n t h e t e c h n o l o g y o f t h e i r a p p l i c a t i o n a n d p l a c e m e n t c a n b e
o b t a i n e d a t th e C e nt r a l L a b o r a t o r y o f t h e In g u r i H y d r o e l e c t r i c S t a t i o n C o n s t r u c t i o n A d m i n i -
s t r a t i o n ( G e or g i a , 3 8 3 7 4 0 , D z h v a r i , C e n t r a l C o n s t r u c t i o n L a b o r a t o r y ) .
581