Note: Descriptions are shown in the official language in which they were submitted.
File No. P6174CA00
ANCHOR BOLT WITH ANTI PROJECTION MECHANISM
BACKGROUND
(a) Field
[0001] The subject matter disclosed generally relates to systems for
anchoring solutions for anchoring
in boreholes made in rock mass, concrete or alike. More particularly, the
subject matter disclosed relates to an
anchor bolt offering improved energy absorption including an anti-projection
mechanism.
(b) Related Prior Art
[0002] Anchors for rock mass support used in mines (open pit or
underground) or civil projects
(tunnels) are known in various shapes, using different mechanisms and offering
different capacities and
behavior. If exceptional energy is released by surrounding environment (i.e.,
seismicity), specialized tendons
are required to contain the potential damages to the structure. That
specialized tendons needs to be able to react
to this exceptional energy since a rigid connection does not exhibit the
required energy dissipating behavior.
[0003] There is therefore a need for an anchoring element that is able to
absorb violent impact loads
such as those occurring during seismic event (natural or induced by mining
activities i.e., rock burst) in an
energy dissipating manner.
SUMMARY
[0004] There is described a rock anchor bolt engineered to absorb violent
impact loads such as those
occurring during seismic events or rock burst in an energy dissipating manner.
The rock anchor bolt comprises
a split sleeve and a bolt component inserted in the split sleeve that, when
pulled outwardly, expends the split
sleeve until a key protruding from the surface of the bolt component abuts a
ring, thereby informing the operator
that appropriate anchoring and pre-tensioning of the anchor bolt in the
borehole is reached through torque
requirement.
[0005] According to an embodiment, there is provided an anchor bolt
designed to absorb energy
during events with sudden energy released.
[0006] According to an aspect, the anchor bolt can adapt in size to the
collar of a borehole to allow
the friction bolt to generate anchorage to the collar of the borehole.
[0007] According to an aspect, the anchor bolt comprises a split sleeve
for better performance at
borehole collar.
[0008] According to an aspect, the split sleeve of the anchor bolt can be
radially compressed, allowing
the anchor bolt to adapt to different sizes of drill holes.
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Date Recue/Date Received 2023-11-28
File No. P6174CA00
[0009] According to an aspect, contact between an anti-ejection system and
a slot in the ring tells the
operator through rotation pressure that the system is engaged to its optimum
anchoring capacity.
[0010] According to an aspect, contact between and anti-ejection system
and the slot in the ring
dissipates energy, including through friction between the ejection system and
the ring slot, to mitigate sudden
energy release.
[0011] Therefore, in some aspects, the description herein relates to a
hybrid bolt designed to be
inserted in a borehole having a borehole wall, the hybrid bolt including: a
sleeve having a first sleeve-end and
an expandable second sleeve-end featuring a longitudinal slit; and a peg
having a first peg-end and a second
peg-end wherein the peg has a diameter increasing toward the second peg-end
thereby providing a frustoconical
surface about the second peg-end, wherein the peg is inserted in the sleeve
with the first peg-end opposed to
the second sleeve-end, and wherein the hybrid bolt, when the peg is pulled
towards the first sleeve-end, has the
frustoconical surface pushing outwards the second sleeve-end which becomes
thereby wedged between the
frustoconical surface and the borehole wall.
[0012] In some aspects, the description herein relates to a hybrid bolt,
further including a wedge ring
inserted between the peg and the sleeve at the second sleeve-end, wherein
pulling the peg towards the first
sleeve-end wedges the wedge ring between the peg and the sleeve.
[0013] In some aspects, the description herein relates to a hybrid bolt,
wherein the wedge ring includes
a longitudinal groove parallel to the slit of the sleeve.
[0014] In some aspects, the description herein relates to a hybrid bolt,
wherein the wedge ring includes
an outwardly extending lip adapted to abut against the second sleeve-end when
the peg is pulled towards the
first sleeve-end.
[0015] In some aspects, the description herein relates to a hybrid bolt,
wherein the wedge ring includes
a longitudinal body extending within the sleeve, the longitudinal body having
a variable thickness increasing
towards the first sleeve-end.
[0016] In some aspects, the description herein relates to a hybrid bolt,
wherein the sleeve has an
external diameter decreasing towards the second sleeve-end.
[0017] In some aspects, the description herein relates to a hybrid bolt,
wherein the sleeve has a slit
extending from the first sleeve-end to the second sleeve-end.
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File No. P6174CA00
[0018] In some aspects, the description herein relates to a hybrid bolt,
wherein the slit narrows towards
the second sleeve-end.
[0019] In some aspects, the description herein relates to a hybrid bolt,
wherein the sleeve includes a
key groove.
[0020] In some aspects, the description herein relates to a hybrid bolt,
wherein the key groove extends
from the first sleeve-end, and the peg includes a body and a key protruding
from the body, wherein the key is
adapted to take place in the key groove.
[0021] In some aspects, the description herein relates to a hybrid bolt,
further including an abutting
ring slidingly mounted to the first sleeve-end.
[0022] In some aspects, the description herein relates to a hybrid bolt,
wherein the abutting ring
includes a slit.
[0023] In some aspects, the description herein relates to a hybrid bolt,
wherein the key has a key-width
transversal to the peg, and the slit of the abutting ring has a slit-width
transversal to the peg nan-ower than the
key-width.
[0024] In some aspects, the description herein relates to a hybrid bolt,
wherein the abutting ring is
adapted to slide into the sleeve.
[0025] In some aspects, the description herein relates to a hybrid bolt,
wherein the peg includes a
weakness between the first peg-end and the second peg-end, wherein the
weakness induces a foreseeable
location for a breaking point to the peg.
[0026] In some aspects, the description herein relates to a hybrid bolt,
wherein the weakness consists
in one of a hole, of a shaving, of a groove, and of threading.
[0027] In some aspects, the description herein relates to a hybrid bolt,
wherein the weakness is located
between the key and the second peg-end.
[0028] In some aspects, the description herein relates to a hybrid bolt,
wherein the peg includes a
threaded portion extending from the first peg-end towards the second peg-end
over a partial length of the peg.
[0029] In some aspects, the description herein relates to a hybrid bolt,
wherein the peg includes a
body, and a key protruding from the body, and a threaded portion extending
between the first peg-end and the
key.
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File No. P6174CA00
[0030] In some aspects, the description herein relates to a hybrid bolt,
further including a mounting
nut adapted to be mounted to the peg, the mounted nut adapted to butt off
against the abutting ring, pushing the
abutting ring inside the sleeve.
[0031] Features and advantages of the subject matter hereof will become
more apparent in light of the
following detailed description of selected embodiments, as illustrated in the
accompanying figures. As will be
realized, the subject matter disclosed and claimed is capable of modifications
in various respects, all without
departing from the scope of the claims. Accordingly, the drawings and the
description are to be regarded as
illustrative in nature and not as restrictive and the full scope of the
subject matter is set forth in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Further features and advantages of the present disclosure will
become apparent from the
following detailed description, taken in combination with the appended
drawings, in which:
[0033] Fig. IA is a perspective view of an anchor bolt in accordance with
an embodiment;
[0034] Fig. IB is a close-up perspective view of the anchor end of the
anchor bolt of Fig. IA according
to detail portion R;
[0035] Fig. IC is a close-up perspective view of the free end of the
anchor bolt of Fig. IA according
to detail portion P:
[0036] Fig. 2A is a partially exploded perspective view of an anchor bolt
in accordance with an
embodiment;
[0037] Fig. 2B is a close-up perspective view of the free end of an
anchor bolt in accordance with an
embodiment;
[0038] Fig. 3A is a perspective view of a bolt component and a conic ring
of an anchor bolt in
accordance with an embodiment;
[0039] Fig. 3B is a close-up perspective exploded view of the anchor end
of the bolt component and
the conic ring depicted on Fig. 3A according to detail portion AB;
[0040] Fig. 4 is a side elevation view of an anchor bolt mounted with
mounting components in a
borehole drilled in concrete in accordance with an embodiment;
[0041] Fig. 5 is a cross-section of the anchor bolt of Fig. 4 according
to cross-section line J-J;
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File No. P6174CA00
[0042] Fig. 6 is a side elevation view of an anchor bolt and mounting
components associated therewith
mounted in a borehole and in an initial position once hammered in placed in
the borehole, with no tension
exerted over the anchor bolt, in accordance with an embodiment;
[0043] Fig. 7 is a side elevation view of the anchor bolt and mounting
components associated
therewith of Fig. 6 in a tensioned position following tension being exerted in
the anchor bolt through tightening
of the hemispherical anchor nut;
[0044] Fig. 8 is a side elevation view of the anchor bolt and mounting
components associated
therewith of Fig. 6 in an over-tensioned position;
[0045] Fig. 9 is a cross-section side elevation view of an anchor bolt in
an initial position in accordance
with an embodiment;
[0046] Fig. 10 is a close-up cross-section side elevation view of the
anchor end of the anchor bolt
depicted on Fig. 9;
[0047] Fig. 11 is a side elevation view of a split sleeve of an anchor
bolt in accordance with an
embodiment;
[0048] Fig. 12 is a plan view of the split sleeve of Fig. 11;
[0049] Fig. 13 is a cross-section view of the split sleeve of Fig. 12
according to cross-section line N-
N;
[0050] Fig. 14 is a plan view of the bolt component of an anchor bolt in
accordance with an
embodiment;
[0051] Fig. 15 is an elevation view of the bolt component of Fig. 14;
[0052] Fig. 16 is a cross-section view of the bolt component of Fig. 15
according to cross-section line
AJ-AJ;
[0053] Fig. 17A is an axial elevation view of a conic ring of an anchor
bolt viewed from the anchor
end of the anchor bolt in accordance with an embodiment;
[0054] Fig. 17B is a cross-section view of the conic ring of Fig. 17A
according to cross-section line
U-U;
[0055] Fig. 18A is an axial elevation view of an abutting ring of an
anchor bolt viewed from the free
end of the anchor bolt in accordance with an embodiment;
Date Recue/Date Received 2023-11-28
File No. P6174CA00
[0056] Fig. 18B is an elevation side view of the abutting ring of Fig.
18A;
[0057] Fig. 19A is an axial elevation view of a mounting nut used to
mount an anchor bolt to a
borehole in accordance with an embodiment;
[0058] Fig. 19B is a side elevation view of the nut of Fig. 19A;
[0059] Fig. 20 is an axial schematic view of mm-max dimensions of the
abutting ring in accordance
with an embodiment; and
[0060] Fig. 21 is an elevation perspective view of a hemispherical anchor
nut adapted to be screwed
on anchoring bolt in accordance with an embodiment.
[0061] It will be noted that throughout the appended drawings, like
features are identified by like
reference numerals.
DETAILED DESCRIPTION
[0062] The realizations will now be described more fully hereinafter with
reference to the
accompanying figures, in which realizations are illustrated. The foregoing
may, however, be embodied in many
different forms and should not be construed as limited to the illustrated
realizations set forth herein.
[0063] With respect to the present description, references to items in
the singular should be understood
to include items in the plural, and vice versa, unless explicitly positioned
otherwise or clear from the text.
Grammatical conjunctions are intended to express any and all disjunctive and
conjunctive combinations of
conjoined clauses, sentences, words, and the like, unless otherwise positioned
or clear from the context. Thus,
the term "or" should generally be understood to mean "and/or" and so forth.
[0064] Recitation of ranges of values and of values herein or on the
drawings are not intended to be
limiting, refen-ing instead individually to any and all values falling within
the range, unless otherwise indicated
herein, and each separate value within such a range is incorporated into the
specification as if it were
individually recited herein. The words "about," "approximately," or the like,
when accompanying a numerical
value, are to be construed as indicating a deviation as would be appreciated
by one of ordinary skill in the art
to operate satisfactorily for an intended purpose. Ranges of values and/or
numeric values are provided herein
as examples only, and do not constitute a limitation on the scope of the
described realizations. The use of any
and all examples, or exemplary language ("e.g.," "such as," or the like)
provided herein, is intended merely to
better illuminate the exemplary realizations and does not pose a limitation on
the scope of the realizations. No
language in the specification should be construed as indicating any unclaimed
element as essential to the
practice of the realizations.
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File No. P6174CA00
[0065] In the following description, it is understood that terms such as
"first", "second", "top",
"bottom", "above", "below", "interior", "exterior", and the like, are words of
convenience and are not to be
construed as limiting terms.
[0066] It will be noted that throughout the appended drawings, like
features are identified by like
reference numerals.
[0067] Referring now to the drawings, and more particularly to Figs. 1A-C
and 2A-B, a hybrid bolt,
hereinafter referred to as an anchor bolt 100, is adapted to be inserted to a
borehole, first through hammering,
and afterward through tightening of a nut, in concrete, rock, or similar
material. The anchor bolt 100 is adapted
to provide an anchoring solution that tells the user on when the necessary
initial tension to be exerted in the
anchor bolt 100 during the installation is reached. The anchor bolt 100 is
further able to absorb violent impact
loads such as those occurring during seismic events or rock burst in an energy
dissipating manner.
[0068] The anchor bolt 100 has an anchor end 102 and a free end 104
opposed to the anchor end 102,
and a body 106 extending in-between. The anchor bolt 100 comprises a bolt
component 120, that can be
generally called a peg, mounted into a split sleeve 150, the bolt component
120 being longer than the split
sleeve 150 and extending beyond the split sleeve 150 in both directions in an
initial position. A conic ring 180
takes place between the bolt component 120 and the split sleeve 150 about the
anchor end 102. An abutting
ring 200 takes place between the bolt component 120 and the split sleeve 150
about the free end 104, butted up
by a mounting nut 230.
[0069] Referring additionally to Figs. 3A and 3B, the bolt component 120
comprises a generally
cylindrical body 122 between a first position 124 and a second position 126,
with the distance between the first
position 124 and the second position 126 being longer than the length of the
split sleeve 150. Beyond the first
position 124 toward the anchor end 102, the bolt component 120 comprises a
wedge portion 128 having an
increasing conical shape toward the anchor end 102 of the anchor bolt 100
forming therethrough a frustoconical
surface. Distant from the first position 124, a key 130 extends axially over
the surface of the cylindrical body
122 between a fourth position 132 and a fifth position 134. The key 130 is
further protruding radially, having
a generally longitudinal portion defining an axial protrusion over the surface
of the generally cylindrical body
122 that extends transversally, aka perpendicular to the longitudinal
orientation and radial orientation of the
bolt component 120 over a transversal width.
[0070] Referring additionally to Figs. 14 to 16, a threaded portion 138
of the bolt component 120
extending between at least a portion of the length between the fifth position
134 and the second position 126 is
threaded to have the mounting nut 230, Figs. 19A-19B, screwed there on such as
to be able to abut the abutting
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Date Recue/Date Received 2023-11-28
File No. P6174CA00
ring 200 before the insertion of the anchor bolt 100 in the borehole 302, and
an external nut, e.g., hemispherical
anchor nut 260, Fig. 21, screwable over the bolt component 120 to exert
tension in the anchor bolt 100 after
the anchor bolt having been hammered in the borehole 302.
[0071] According to an embodiment, the bolt component 120 features,
between the positions 124 and
132, a weakness taking, e.g., the form of a hole 136, wherein the nature and
dimension(s) of the weakness are
selected based on the desired position and characteristics leading to failure
of the anchor bolt 100, aka the
maximum tension or energy the anchor bolt 100 may undergo before it breaks.
[0072] According to another embodiment (not depicted), the weakness is
provided through the
presence of shaving(s) over the external surface of the anchor bolt 100.
According to another embodiment (not
depicted), the weakness is provided through the presence of groove(s), wherein
number, shape, orientation,
location, depth and number of groove(s) may vary with embodiments. According
to another embodiment (not
depicted), the weakness is provided through the presence of threading.
[0073] Accordingly, it is contemplated therethrough that the anchor bolt
100 may comprise a
weakness embodiment as a local modification of physical characteristics of
material of the anchor bolt 100 is
order to induce a foreseeable location for a breaking point to the anchor bolt
100.
[0074] Refen-ing now to Figs. 11 to 13, the split sleeve 150 consists in
a generally hollow cylindrical
body 152 of an interior dimension adapted to house the generally cylindrical
body 122 of the bolt component
120 and being split, aka having a slit that extends over its whole length,
thus having a C-shaped cross-section.
The generally hollow cylindrical body 152 extends between a first position 154
and a second position 156.
Beyond the second position 156 in the direction of the anchor end 102, the
split sleeve 150 comprises an
expandable anchor portion 160 having a slightly decreasing conical shape
toward the anchor end 102. The
anchor portion 160 comprises a plurality of slits, e.g., longitudinal grooves
158, e.g., four (4), allowing a level
of deformation of the anchor portion 160 when the frustoconical surface of the
wedge portion 128 is forced to
enter the expandable anchor portion 160.
[0075] as depicted particularly on Figs. 11 and 12, according to an
embodiment the longitudinal slit
narrows about the anchor end 102.
[0076] According to an embodiment, the split sleeve 150 consists in a
partially wrapped component,
e.g., wrapped over about two hundred and seventy (270) degrees, featuring a
longitudinal aperture 164 of a
designed dimension allowing the bolt component 120 to be inserted inside the
split sleeve 150 thereby and the
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Date Recue/Date Received 2023-11-28
File No. P6174CA00
split sleeve 150 to be compressed until no clearance remains between the split
sleeve 150 and the bolt
component 120.
[0077] Still referring to Figs. 11 to 13, the split sleeve 150 comprises
at least one longitudinal groove
166, preferably opposed to the longitudinal aperture 164, adapted to receive
the key 130 of the bolt component
120 and to limit the course of the key 130 during the tensioning operation of
the anchor bolt 100, as over-
tensioning occurs as will be discussed below in more details.
[0078] Referring to Fig. 17A-17B and Figs. 9-10, the anchor bolt 100
comprises a wedge ring, e.g.,
conic ring 180, taking place between the bolt component 120, about the wedge
portion 128, and the anchor
portion 160 of the split sleeve 150. The conic ring 180 is adapted, when
pushed by the wedge portion 128 when
the bolt component 120 is pulled towards the other end, to force its way
inside the anchor portion 160, thereby
deforming the anchor portion 160 outwardly so the exterior face of the anchor
portion 160 would mate the
surface of the borehole to anchor the anchor bolt 100 therein.
[0079] According to a preferred embodiment, the conic ring 180 comprises
a cylindrical exterior face
182, and a conical interior face 184 thereby a longitudinal body therebetween
of variable thickness, providing
a conduit sized to insert the generally cylindrical body 122 of the bolt
component 120 therein. The conic ring
180 comprises an outwardly extending lip 186 on the wide end of the conical
interior face 184. The conic ring
180 features a pair of grooves 190 extending over a substantial portion of the
length 192 of the conic ring 180
allowing deformation of the conic ring 180. According to embodiments, the
grooves 190 extends over a greater
length than 50%, 60%, 70%, 80% or 90% of the total length 192 of the conic
ring 180. According to an
embodiment, depicted on Figs. 3A and 3B, the conic ring 180 is made of two
pieces that can be assembled
around the cylindrical body 122 and maintained in place between the bolt
component 120 and the split sleeve
150 once these components are assembled.
[0080] Referring to Figs. 18A-B, the abutting ring 200 is designed to
take place between the bolt
component 120 and the split sleeve 150 about the free end 104, inserted in the
split sleeve 150 and abutted on
its lipped face 216 closest to the free end 104 by the mounting nut 230. The
abutting ring 200, according to an
embodiment, consists in a partially wrapped component covering e.g., about 300
degrees, featuring an aperture
202 sized to insert the bolt component 120 in the abutting ring 200
therethrough. The abutting ring 200
comprises a cylindrical outer face 206 sized to be inserted in the split
sleeve 150, and a cylindrical inner face
208 sized to receive the generally cylindrical body 122 of the bolt component
120. The abutting ring 200
comprises an outwardly extending lip 210 designed to be wedged between the
extremity of the split sleeve 150
about the free end 104 and the mounting nut 230. The abutting ring 200
features a groove 212 opposed to the
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Date Recue/Date Received 2023-11-28
File No. P6174CA00
aperture 202 that is sized to receive and allow longitudinal displacement of
the key 130. The groove 212 is
designed, when the abutting ring 200 is mounted between the bolt component 120
and the split sleeve 150 with
the lip 210 abutting the split sleeve 150, to limit the course of the key 130
to a distance from the extremity of
the split sleeve 150 about the free end 104 as is explained below.
[0081] It is worth noting that according to an embodiment the groove 212
is narrower than the key
130 and it features a chamfered entry, thereby having the key 130 generating
deformation and friction when
the abutting ring 200 pushes against the key 130 such that the key 130 must
enter in the groove 212 for the
abutting ring 200 to continue its course. That situation provides indication
when the correct installation is
reached, both through positioning and through torque reading.
[0082] Referring to Figs. 4 and 5, according to a preferred embodiment,
the apertures 164, 202 are
sized to allow to mount the bolt component 120 into the split sleeve 150 with
some deformation of the split
sleeve 150 and abutting ring 200.
[0083] Referring to Fig. 4 and 5, as discussed before, the anchor bolt
100 is designed to be mounted
through hammering percussion (i.e. hydraulic hammer) in the borehole 302
drilled in the rock mass formation
304 or alike. The borehole 302 is drilled to a recommended diameter of thirty-
eight (38) mm but can
accommodate irregularities in the borehole 302, or smaller diameter (as small
as thirty-five (35) mm) when
used in soft rock formation which allow small deformation of the material, for
the exemplary anchor bolt 100
having an external normal (no-compressed) diameter of about thirty-nine (39)
mm defined by the diameter 168
of the split sleeve 150. The cylindrical body 122 of the exemplary bolt
component 120, inserted in the split
sleeve 150, has a diameter 140 of about twenty-five (25) mm. The longitudinal
aperture 164 of the split sleeve
150 allows the split sleeve 150 to be compressed for insertion in the borehole
302, thereby mating the diameter
308 of the borehole 302 once inserted.
[0084] Referring additionally to Figs. 6 to 8, the anchor bolt 100 is
depicted in three typical positions
the anchor bolt 100 is able to adopt, with the selected position depending on
installation parameters and rock
mass conditions.
[0085] Depicted on Fig. 6, the anchor bolt 100 is initially, after being
inserted, in an initial position
when no internal stress is exerted on the anchor bolt 100. For its insertion
in the borehole 302, the anchor bolt
100 is hammered in the borehole 302 with the bolt component 120 inserted in
the split sleeve 150, the conic
ring 180 and the abutting ring 200 interfacing between the split sleeve 150
and the bolt component 120 about
the anchor end 102 and at the free end 104, and the mounting nut 230 abutting
the lipped face 216 of the
abutting ring 200. The wedge portion 128 extends beyond the conic ring 180.
The extent of the wedge portion
Date Recue/Date Received 2023-11-28
File No. P6174CA00
128 is limited by the key 130 abutting the groove 166. The threaded portion
138 extends beyond the surface of
the rock with a washer 240 and a hemispherical anchor nut 260 mounted on the
free portion of the anchor bolt
100 out of the rock mass formation 304. To be noted that, the distance at
which the hemispherical anchor nut
260 is screwed determine the limit penetration of the anchor bolt under
hammering, aka without exerted internal
tension in the anchor bolt 100. It is further to be noted that other
components, not depicted, may also be
anchored through the anchor bolt 100, for instance protection grid, anchoring
loop and straps, and plates.
[0086] Depicted on Fig. 7, the anchor bolt 100 is exerted internal stress
by tightening the
hemispherical anchor nut 260 until it reaches the tensioned position. More
precisely, the hemispherical anchor
nut 260 is screwed over the threaded portion 138 with the bolt component 120
moving outward with every
revolution of the hemispherical anchor nut 260. As a result, on the anchor end
102, the wedge portion 128
gradually penetrates more in the split sleeve 150, forcing anchoring end of
the split sleeve 150 to expand and
to abut the surface of the borehole 302. About the free end 104, the mounting
nut 230, and the key 130 move
also outward, with the key 130 moving in the at least one longitudinal groove
166 away from its bottom until
butting off the abutting ring 200. When the key 130 pushes the abutting ring
200 and is blocked thereby, the
torque necessary to rotate the hemispherical anchor nut 260 increases,
informing the operator that the optimal
tensioned position is reached. It is to be noted that this same process
applies in a variety of diameters of
boreholes, e.g., for the exemplary anchor bolt 100 a borehole diameter of
thirty-eight (38) mm in a hard rock
mass formation, and a borehole diameter of as low as thirty-five (35) mm in a
soft rock mass formation.
[0087] Referring additionally to Fig. 20, the schematic depicts that the
outer diameter of the abutting
ring 200 inserted the split sleeve 150 through hammering percussion to assure
anchoring of the split sleeve
about the entry of the borehole 302 in various hole dimension (e.g., thirty-
five (35) to thirty-eight (38) mm),
for instance when installed in a borehole 302 of a smaller diameter, normally
performed in soft rock formation.
On Fig. 20, the abutting ring 200 is depicted being in its original non-
compressed shape 200', that is greater
than the space between the wall of the borehole 302 and the split sleeve 150,
to an exemplary compressed shape
200", limited over a minimum value by the diameter of the bolt component 120
in which the aperture changed
from its maximum aperture to its minimum aperture greater than zero (0).
[0088] Depicted on Fig. 8, the anchor bolt 100 may adopt additional
outward displacement of the bolt
component 120 if ground conditions allow (i.e. very soft rock mass or void).
If conditions allow it, the wedge
portion 128 at the anchor end 102 will penetrate even more in the split sleeve
150, forcing the conic ring 180,
and accordingly the split sleeve 150, to increase even more their diameters
against with the outside of the split
sleeve 150 mating the surface of the borehole. About the free end 104, the
outward course of the bolt component
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Date Recue/Date Received 2023-11-28
File No. P6174CA00
120 would result in the key 130 forcing its way in the groove 212. Since the
width of the groove 212, e.g., 5
mm, is smaller than the width of the key, e.g., 10 mm, the key 130 will
encounter resistance against that
displacement at set torque load for a set length indicating to operator that
bolt has passed optimal position.
However, the extra course of the key 130 will be stopped by the bottom of the
groove 212, in combination with
the abutting ring 200 coming in contact with the hemispherical anchor nut 260
or equivalent, preventing any
further axial displacement and forcing rotation of the assembly stopped by key
130 sitting against the split
sleeve 150 where the over-tensioned position is reached. The measurement of
the protruding length 170
combined to sudden high torque load will indicate to the operator that the
installation is not correct.
[0089] Should the anchor bolt 100 reach failure with high energy
absorbency, the hole 136 is designed,
by diameter and/or depth, to induce failure at a specific position located
beyond the anti-ejection system, aka
beyond the key 130 and cooperating components, in the direction toward the
anchor end 102. Forced mating
of the split sleeve 150 about the abutting ring 200 prevents, through friction
between the split sleeve 150 and
the wall of the borehole 302 at that position, the freed portion of the anchor
bolt 100 to be ejected at high speed.
In other words, the forced expansion of the split sleeve 150 of the anchor
bolt 100 both about the anchor end
102 and about the entry of the borehole 302 prevents a breaking anchor bolt
100 to be transformed into a high
velocity projectile forcibly ejected from the borehole 302.
[0090] According to a first realization, the wedge portion 128 has a
first diameter about the cylindrical
body 122 of twenty-five (25) mm, and a second diameter 142 at its anchor end
of thirty-five (35) mm, with the
increase being regular and over a length of about fifty-seven (57) mm. The
displacement of the key 130 between
the initial position and the tensioned position is about thirty-eight (38) mm.
Further displacement of the key
130 to reach the over-tensioned position is defined by the length of the
groove 212, and is typically of about
thirty (30) mm.
[0091] In other realizations, the length of the anchor bolt 100, the
length of the portion of the anchor
bolt 100 extending beyond the surface of the e.g., rock mass formation,
distances between the positions, the
pressure applied over the surface of the borehole, general resistance of the
anchor bolt 100, etc. may be set to
different values with changes in the design not departing from the design
concept taught through the present
exemplary realization.
[0092] It must be mentioned that some details of the present design may
be omitted, or replaced with
alternatives, in alternative designs without substantially affecting the way
the present anchor bolt 100 operated.
[0093] Therefore, while a preferred embodiment has been described above
and illustrated in the
accompanying drawings, it will be evident to those skilled in the art that
modifications may be made without
12
Date Recue/Date Received 2023-11-28
File No. P6174CA00
departing from this disclosure. Such modifications are considered as possible
variants comprised in the scope
of the disclosure.
13
Date Recue/Date Received 2023-11-28
