Note: Descriptions are shown in the official language in which they were submitted.
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Expandable rock bolt with indicator of clamping
Art Domain
This invention concerns design solution of an expandable rock bolt with an
indicator of its clamping in the borehole which is designed not only for
provision and
reinforcement of consistency of the rock especially during driving of tunnels,
mine
corridors and chambers but also for stabilisation of rock walls, slopes and
dikes or for
formation of suspension reinforcement especially for tunnel and mine works
with
possible use in civil engineering.
Present Prior Art
For stabilisation and reinforcement of rock environment are used various types
of
rock bolts or anchors whose construction and material design differs in
dependence on
kind of rock. Among the most commonly used types are hydraulic expandable
bolts
which are procured with a tubular expansion tube which is procured on its both
ends
with end parts and whose surface is lengthwise in one or several lines
deformed. These
bolts are pushed into a beforehand drilled opening and subsequently is, into
an
expansion tube, forced a pressure medium whereby there comes to its expansion
in the
borehole, to formation of a frictional force of the tube of the bolt toward
the wall of the
borehole and thereby to its clamping.
An exemplary design of a hydraulic expandable bolt of this type is known from
the file CZ 25706 U1 where is described a rock bolt which includes a tubular
expansion
tube whose transversal cross section has a deformed shape which forms on the
surface
of the tube at least one lengthwise groove and which is on its both ends
finished with
transitional annular caps in which are non-demountable fixed an outlet valve
and an
inlet valve. Yet this design does not enable any indication of expansion of
the 'bolt and
its clamping in the borehole. In the file W02013173901 is described an
expandable rock
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bolt with a tubular expansion tube whose lengthwise cross section has a
deformed
shape which forms on the surface of the tube one lengthwise groove. The
expansion
tube is on its both ends finished with fixed tubular end parts and it is
enlaced with at
least one lengthwise adjustable sleeve which is fixable in any position. Yet
in this design
there is not described pressure control in the bolt and also not detection of
its expansion
or its correct clamping in the rock. In the file W02004099570 is described a
method for
installation of expandable rock bolts by the help of pressurized of beforehand
defined
pressure by the help of a device with a control system which ensures keeping
of the
pressure for a certain time period and it is equipped with signalisation of
efficiency of
performed process or its failure. This design does enable pressure control in
the bolt but
there is not ensured detection of proper expansion and clamping in the
borehole. In the
file JP2005232761 is solved method of metering of generation of transversal
tension of
an expansion tube of a bolt inside of drill by the help of electric
tensiometers which are
connected to a detection unit. This design demands more complicated electronic
equipment and does not provide information concerning perfect clamping of the
bolt in
the borehole. In the file W02015176081 is described visual detection of
filling of drill
with medium by the help of an indication element which is part of a vent tube
through
which goes away air from gradually filled drill and which enables air passage
but does
not enable passage of viscous material. After filling of the drill with the
viscous material
is then the indication element pushed out from the vent tube which is visually
noticed.
This design is not possible to use for hydraulic expandable bolts. The file
W02009066246 solves detection of achievement of defined pressure in tubular
expansion tube of expandable bolt with an indicator in its front end part
which is after
achievement of defined pressure pushed out from the end part which is visually
noticed.
This design indicates only pressure inside of the bolt but it does not enable
indication of
expansion of the bolt. In the file ZA200506692 is described similar design of
pressure
indication in tubular expansion tube of expandable bolt as in above mentioned
file
W02009066246. Likewise, in this case is not possible to detect expansion of
the bolt
and its perfect clamping in the borehole.
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The aim of presented invention is modification of expandable rock bolt design
which ensures its perfect functionality and check of its anchorage with
indication of
perfect clamping in the borehole.
Essence of the invention
Defined goal is reached with invention which is an expandable rock bolt which
is
formed with a tubular expansion body whose transversal cross section has a
deformed
shape which forms on the surface at least one lengthwise groove and whose ends
are
procured with caps with a filling component on its inlet side and an end
component on
its outlet side wherein the essence of the invention is that the bolt is
procured with at
least one indicator of clamping which is formed with a hollow tube which is
made of an
elastically compressible material and which is placed in the wall of the
expansion body
along which is the indicator taken out on the visible side for the staff
whereas at least in
part on the internal cavity of the tube of the indicator is placed indication
medium.
In an advantageous design is the indicator of clamping formed with a tube
whose
inner end is sealed with a stopper and in whose internal cavity is placed a
tubular
capsule which is made of easily destructible material and is on its both ends
sealed with
stanching sealing and it is filled with indication medium whereas in the end
entry part of
the internal cavity of the tube is fixed a porous element.
Furthermore it is advantageous when position of the tubular capsule in the
internal cavity is kept with a spacer which is inserted between the front face
of the
tubular capsule and the porous element and when entry part of the internal
cavity of the
tube is procured with a lens-end which is made of transparent material and it
is fixed to
the tube by the help of a fixator and the lens-end is shaped like a lens.
In other advantageous designs is the indicator of clamping formed with tube
whose inner end is firmly sealed and whose internal cavity is divided by a=
partition into
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two parts or is the indicator of clamping formed with tube whose inner end is
firmly
sealed and in whose internal cavity is placed set of capsules which are made
of easily
destructible material and whose position in the internal cavity is kept with a
plug.
For particular types of bolts is advantageous when the indicator of clamping
is
equipped with an extension tube which is in the tube fixed by the help of a
bung and
which is in its end part procured with the lens-end which is made of
transparent material
and which is fixed to the extension tube by the help of the fixator.
And finally it is advantageous when the indication medium consists of coloured
liquid medium or a single-base or multi-base chemical compound or gel or pasta
or
foam or powder.
With presented invention is reached new and higher efficiency in the fact that
with new structural modification is ensured transmission of information
concerning
perfect clamping of the bolt in the borehole whereby is basically eliminated
possibility
of imperfect anchorage owing to any factors arisen during realization of the
borehole,
placement of the bolt into the borehole and expansion of its body.
According to one aspect of the present invention, there is provided an
expandable rock bolt which is formed with an expansion body whose transversal
cross
section has a deformed shape which forms on a surface at least one lengthwise
groove
and whose ends are provided with caps on an inlet side and an end component on
an
outlet side, wherein: the expandable rock bolt is equipped with an indicator
of clamping
which is formed with a hollow tube which is made of an elastically
compressible
material and which is placed on a wall of the expansion body; the indicator of
clamping
having a visible side for an operator in a front part of an internal cavity of
the tube ;
in the internal cavity of the indicator of clamping is placed indication
medium.
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Description of figures in enclosed drawings
Particular examples of design of the invention are schematically illustrated
in
enclosed drawings where:
Fig. 1 is a view of in-rock clamped rock bolt after expansion of tubular body
and
after deformation of the indicator,
Fig. 2 is a longitudal section of the rock bolt from the fig. 1 which is
inserted in
the borehole and illustrated in the state before expansion of the tubular
body,
Fig. 3 is a longitudal section of basic design of the indicator of clamping,
Fig. 4 is a longitudal section of an alternative design of the indicator of
clamping
from the fig.3 which is formed without a lens-end,
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Fig. 5 is a longitudal section of an alternative design of the indicator of
clamping
from the fig.3 which is modified for use of mastic as indication medium,
Fig. 6 is a longitudal section of an alternative design of the indicator of
clamping
which is equipped with an extension tube,
Fig. 7 is a longitudal section of an alternative design of the indicator of
clamping
with use of indication medium in the form of polyurethane capsules,
Fig. 8 is a longitudal section of lower part of the rock bolt with illustrated
cross
section of the expansion body with an alternative placement of the indicator
of clamping
and its side outlet through an inlet neck of the bolt,
Fig. 9 is a longitudal section of lower part of the bolt with an alternative
placement
and side outlet of the indicator of clamping with the extension tube from
fig.6,
Fig. 10a) and fig.10b) are front and side views of the rock bolt with a thread
extension which is placed deep in the borehole and which is procured with the
indicator
of clamping with the extension tube which is placed along the body of the
bolt,
Fig. 11 is a longitudal section of the rock bolt with inserted alternative
design of
the indicator of clamping with polyurethane capsules according to the fig.7,
Fig. 12 to fig. 20 illustrate alternative cross sections of the expansion body
of the
rock bolt with illustration of possible placement of one or more indicators.
The drawings illustrate presented= invention and consequently described
examples of particular design but they do not in any case anyhow limit extend
of the
protection stated in the definition yet only clarify essence of the invention.
Examples of lay out of the invention
The rock bolt according to the invention which is designed for clamping in the
borehole 101 of a rock massif 1 is formed in its basic design according to the
fig.1 with a
expansion body 2 whose cross section has deformed shape, for instance C -
profile,
trefoil, quatrefoil, sixfoil, star with various number of tails, teardrop etc.
as it is illustrated
in fig. 12 to fig. 20 which forms on the surface at least one lengthwise
groove 21. The
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expansion body 2 is on its both ends procured with firmly fixed, preferably
welded,
transitional annular end caps 3 which are formed in the shape of an annulus
and are
recessed with a non-illustrated inlet valve and an outlet valve of standard
design. The
caps 3 of the bolt are then equipped with other non-illustrated structural and
technological elements which can be according to the type of the bolt a
filling head or a
drilling head and a drilling bit. In the lower part of the expansion body 2 is
then on its
surface freely displaceable embedded a cover washer 4 which can be spherically
shaped as it is obvious from fig.1, fig. 2, and fig. 8, or it can be flat as
it is illustrated in
fig. 9.
An integral part of the bolt is a clamping indicator 5 which is in its basic
design
which is illustrated in fig. 3 formed with a hollow tube 51 made of
compressible material
for example plastic, metal of non-metal foil, whose inner end 511 is firmly
sealed, for
example glued, with a stopper 52. In an internal cavity 512 of the tube 51 is
placed a
capsule 53 which is filled with unmarked indication medium which is made of
easily
destructible material preferably from glass and which is on its both ends
sealed with
stanching sealing 54. Position of the capsule 53 is in selected part of the
internal cavity
512 kept with a rod spacer 55 which is inserted between a non-illustrated
front part of
the capsule 53 and a porous element 56 which is fixed, for example glued, in
the end
entry part of the internal cavity 512 of the tube 51 and it is formed from
material which
enables passage of indication medium. The entry part of the internal cavity
512 of the
tube 51 is then procured with a lens-end Si which is shaped preferably like a
lens and is
made of transparent material and is fixed to the tube 51 by the help of a
fixator 58 which
is formed for example from a shrink wrap. Whole indicator 5 is then embedded
in a
lengthwise groove 21 on the wall of the expansion body 2 where it is placed in
the way
that the end part of the tube 51 of the indicator 5 which is procured with the
lens-end 57
stands-out out from the end cap 3 in the way that the lens-end 57 is visible.
When the rock bolt is used the indicator 5 is inserted into the lengthwise
groove
21 on the wall of the expansion body 2 of the rock bolt in the way for the end
part of its
tube 51 to stand out from the lower end cap 3 and to be visible. After
insertion into the
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borehole 101 is the bolt connected to a non-illustrated source of high
pressure hydraulic
medium which is led into the cavity of the expansion body 2 whereby this
expansion
body 2 starts to expand transversally and to fill cross section of the
borehole 101. Due
to expansion of the expansion body 2 is the tube 51 of the indicator 5
gradually
deformed and consequently there comes to destruction of the capsule 53 from
which
starts to run out the indication medium which runs down through the internal
cavity 512,
leaks through the porous element 56 into the space of the lens-end 57 and
whereby is
transmitted information about filling-up of the borehole 101 with the
expansion body 2 of
the bolt and its perfect clamping in a rock massif 1.
Described design of the bolt and the indicator 5 is not only possible design
according to the invention, but as it is clear from fig. 4 entry part of the
internal cavity
512 of the tube 51 does not have to be equipped with the lens-end 57, but it
can be
finished only with the porous element 56. As an indication medium can be used
any
coloured liquid medium for example a spirit colour or a luminescent colour or
the
indicator 5 can be filled with suitable single-base or multi-base chemical
compound, gel,
pasta, foam or powder. In case of use of non-liquid indication medium this
does not
have to be inserted into the capsule 53, but certain part of the internal
cavity 512 of the
tube 51 of the indicator 5 which is separated by a partition 513 can be
directly filled with
it as is it evident form fig. 5. For different types of the bolts whose
exemplar designs are
illustrated in fig. 8 to fig. 10 is then possible to equip the indicator 5
with an extension
tube 59 which is in the tube 51 fixed by the help of a bung 591 as is it
illustrated in fig.6.
This modification enables outlet of the indication medium from the internal
cavity 512
sideways, along the expansion body 2 of the bolt namely through a filling neck
according to the fig. 8 or out of the filling neck according to the fig. 9,
possibly next to
the expansion body 2 according to the fig.10a) and 10b). And last but not
least in the
internal cavity 512 of the tube 51 does not have to be inserted one big
capsule 53 but it
can be replaced with a set of capsules 53 as is it clear from the fig.7 and
fig. 11.
Position of the capsule 53 in the internal cavity 512 does not have to be kept
with a
spacer 55 this can be replaced with a plug 6 as is it also clear from fig.7.
And as is it
visible in fig.12 to fig. 20 it is possible to use, for particular types of
deformed expansion
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bodies 2 for indication of proper expansion of the bolt in a non-homogenous
rock massif
1, more than one for example two or three indicators 5 which are inserted into
various
lengthwise grooves 21 of the expansion body 2 of the bolt.
Industrial usability
The expandable rock bolt according to the invention is designed not only for
stabilisation and reinforcement of consistency of rock mass especially during
boring of
tunnels, mine corridors and chambers but also for stabilisation of rock walls,
slopes and
dykes in the form of grouting with expected use in mines for mining of coal or
ores or for
various applications in civil engineering.
