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APPLICATION
Different types of rock bolts developed by the staff
of the company have been applied in the coarse of the years in almost
of all underground ore-mines and exploration enterprises in Bulgaria.
In the past the expansion shell rock bolts have been used manly whose
consumption pro year reach about 50 000 peaces. They have been used
manly for supporting the underground openings in the ore mines:
“Gorubso”, “Burgas Copper Mines”, “Chelopech”, “Eliseina”,
“Osogovo” and coal mines “Balkanbas”.
Since 1985 the expansions rock bolts have been
moved away by frictional pipe anchor TFA. At present the
consumption of frictional rock bolts exceeds of 20 000 peaces pro year.
At ore mines TFA are used for supporting the
development and extraction openings. Under the condition of these
mines, where rocks are of higher strength properties but of different
structure and structural disturbances (jointed rocks, blocked rocks,
stratified rocks etc.) anchors are applied mainly as an independent
support and only at more loosen zones meshwork and shotcrete are
applied for rock weathering protection. Comparatively small cross
sections of mine openings at these mines necessitated the use of
anchors of length 1,20 m to 2,00 m. Furthermore, anchors of even
smaller length, from 0,6 m to 1,0 m, are used for supporting the walls
of the stalls(stores) with the purpose of preventing the ore
impoverishment from barren as well as a supplementary means for mesh
stretching over rock surface in stalls.
In coal mines, where bedded rocks typical with their low strength
properties are prevailing (uni-axial compression strength from 6 to 20
Mpa) anchors are applied in a combination with wood headers and network
or yieldable metal rings and lagging. Аnchor lengths applied are 1,80
m, 2,00 m and 2,40 m. In these cases several times reducing of
convergence and material and labor saving due to the elimination of
repair is achieved.
In the mines of the company “Chelopech nining”
frictional rock bolts TFA are used for development and extraction
openings by the lengths of 1,5 m and 2,0 m respectively in quantity of
6 000 peaces pro year. For hanging the mine loads Rock bolts KPV with
rigid and elastic bonds are used.
The company “Geotechmin” use rock bolts TFA for
supporting the roadways tunnels in open pit mine “Elatzite med” . The
rock bolting there consist of rock bolts TFA, steel mesh and shotcrete.
In the mines of “ Gorubso Zlatograd” Ltd frictional
rock bolts TFA are used for supporting the underground mine openings
and for hanging the mine loads used KPV with rigid bond.
Anchors TFA are also used at the lead-zinc mine of “Sasa”, Republic of
Macedonia, where they are applied both at development and extraction
mine openings. Preferred anchor length is 2,00 m for roadways and
2,40 m for ore extraction by room and pillar mining.
Rock bolts TFA are applied successfully for supporting the underground
openings in the mines of RTB”Bor” , Republic of Serbia
The TFA anchors were successfully used for supporting a rock slope,
that is a natural wall of a Sport Hall at the town of Veliko Tarnovo,
Bulgaria. Anchors of length 2,40 m were used. Because of the decorative
character of the wall the anchors used were without bearing plates.
After anchor driving to the hole collar a cement-sandy slurry, that
fills the space between the anchor and the hole walls and anchor
itself, was injected. At present the rock wall is used not only for
decoration bit also as a training device for mountaineering.
The vine-cellar in Town of Melnik is supported successfully by rock
bolts TFA, steel mesh and shotcrete . The vine cellar have been
developed in high unstable weak sandstone.
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