Note: Descriptions are shown in the official language in which they were submitted.
9026-IE-SE
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This invention pertains to friction rock stabilizers,
and methods for insertion of such in earth structure bores,
and particularly to an improved friction rock stabilizer so
configured as to facilitate its contraction to render its
insertion into an undersized earth structure bore more facile,
and to a method for insertion of friction rock stabilizers
into undersized earth structure bores.
Friction rock stabilizers are relatively new earth struc-
ture stabilizing devices, and such are best exemplified by
U.S, Patent No. 3,922,867, issued December 2, 1975, and U.S.
Pater,t No. 4,012,913, issued March `22, 1977, both granted to
James J, Scott,
According to the teachings in the referenced Patents,
friction rock stabilizers comprise generally tubular bodies
which may be axially slit ! and which have a free cross-sectional
dimension predetermined to be larger than the transVerse dimen-
sion of the earth structure bores into which they are to be in-
serted. Accordingly, it requires considerable thrusting
~orce to insert such a stabilizer into an undersized bore, The
stabilizer must contract, to accommodate insertion, whereby
the slit is substantially closed during lnsertion and, after
insertion, the stabilizer attempts to rsturn to its original
free dimension; thus it frictionally holds fast to the wall of
the bore and, consequently, stabillzes the~earth structure.
It is an object of this invention to disclose both a fric-
tion rock stabilizer having means formed thereon to facilitate
a pre-insertion contraction thereof for contracted installa-
tion in an u~dersized bore~ and also a method comprising the
pre-insertion contraction, insertion, and contraction release
'riction roc]c stabilizers.
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Particularly, it is an object of this invention to se-t
for-th a friction rock stabilizer for insertion in a bore formed
in an earth structure for stabilizing the structure, comprising
a generally tubular body, said body having an elongate axis
and wall means for frictionally engaging the surface of an
earth structure bore, said body further having a first, free,
relaxed, transverse dimension predetermined to be larger than
the transverse dimension of a bore into which it is to be in-
serted; and said body also having an axially-extended slit
formed through said wall means thereof to permit said body to
assume a second, constrained, transverse dimension which is
smaller than both said first transverse dimension and the
transverse dimension of a bore into which it is to be inserted
wherein said wall means has confronting axially-extended and
spaced-apart surfaces which: (1) define said slit therebetween,
and (2) have key means formed adjacent to said slit-defining
surfaces for: (a) receiving contraction forces thereat9 and
(b) responsive to such forces, for moving said slit-defining
surfaces toward each other.
Another object of this invention is to set forth a
friction rock stabilizer, for insertion in a bore formed in an
earth structure for stabilizing the structure, comprising a
generally tubular body, said body having an elongate, central
axis and wall means for frictionally engaging the surface of
an earth structure bore, said body also having means defining
an axially-extended separation, of a given width9 in said wall
means, and means defining a pair of spaced-apart bearing
surfaces, integrally formed on said body and movable relative
to each other to vary said separation to a width other than
said given width.
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It is also a further object of this invention to teach
a method of inserting a friction rock stabilizer in a bore formed
in an earth structure, for stabilizing the structure, wherein
the bore has a given transverse dimension, and the stabilizer
has a ~irst, free, relaxed, transverse dimension which is greater
than said given dimension and is resiliently contractible to a
second, constrained, transverse dimension which is slightly less
than said given dimension of said bore, comprising the steps of
slidably engaging the stabilizer with a device to cause con-
traction of the stabilizer to said second, constrained, trans-
verse dimension, inserting the contracted stabilizer into the
bore; and disengaging the device to permit a release of the
stabilizer from its contracted constraint.
According to a broad aspect of the present invention,
there is provided a friction rock stabilizer for insertion in
a bore formed in an earth structure for stabilizing the struc-
ture. The stabilizer comprises a generally tubular body having
an elongated axis and wall means for frictionally engaging the
surface of an earth structure bore. The body further has a
first, free, relaxed, transverse dimension predetermined to be
larger than the transverse dimension of a bore into which it is
to be inserted. The body also has an axially-extended slit
formed through the wall means thereof to permit the body to
assume a second, constrained, transverse dimension which is
smaller than both the first transverse dimension and the trans-
verse dimension of a bore into which it is to be inserted. The
wall means as confronting axially-extended and spaced-apart sur-
faces which: (1) define the slit therebetween, and (2) have key
means formed adjacent the slit-defining surfaces for: (a) receiv-
ing contraction forces thereat and (b) responsive to such forces,for moving the slit-defining surfaces toward each other.
~ ccording to a further broad aspect of the present
invention, there is provided a method of inserting a friction
rock stabilizer in a bore formed in an earth structure, for
3~ stabilizing the structure, wherein the bore has a given trans-
verse dimension, and the stabilizer has a first, free, relaxed,
transverse dimension which is greater than the given dimension
and is resiliently contractible to a second, constrained, trans-
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verse dimension which is slightly less than the given dimension
of the bore. The method comprises the steps of slidably engag-
ing the stabilizer with a device to cause contraction of the
stabilizer to the second, constrained, transverse dimension;
inserting the contracted stabilizer into the bore; and disengag-
ing the device to permit a release of the stabilizer from its
contracted constraint.
Further objects of this invention, as well as the novel
features thereof, will become more apparent by reference to the
following description, taken in conjunction with the accompanying
figures in which
Figure 1 is an isometric projection of an end portion of
a friction rock stabilizer, according to an embodiment of the~in-
vention, and a clamping device for use therewith,
Figure 2 is a discontinuous isometric projection of the
stabilizer and clamping device of Figure 1 shown in operative,
engaged relationship,
- Figure 3 is a discontinuous, elevational view of an
alternative embodiment of a friction rock stabilizer, according
to the invention, showing an alternative contracting tool in
use therewith, and
Figure 4 is a cross-sectional view taken along Section
4-4 of Figure 3.
According to the referenced U.S. Patent No. 3,922,867,
an embodiment o~ a friction rock stabilizer may have an axially
extended slit formed therein. Such a stabilizer 10
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is shown in Figures 1 and 2 and according to this inventive
embodiment, has the edges 12 of the slit 14 thereof turned
inward generally toward the central axis 16 thereof.
According to the invention, the stabilizer 10 is forceably
contracted, to move confronting surfaces 18 thereof toward each
other, and to dispose the edges 12 as bearing surfaces or keys.
Thus, the edges 12 slidably receive a clamping device 20. The
device 20, of substantially U-shaped cross-section, has a
flared or widened end 21 which has a width sufficient to
straddle and slidably engage the edges 12 at one end of the
stabilizer. Then, the device 20 is forced along the stabilizer
10, axially, to move the surfaces 18, into proximity, as
aforesaid. The stab;lizer 10, then, being substantially closed
along the slit 14, the edges 12 lie as closely-coupled, par-
allel ribs. The device 20, slidably and axially engaged with
the edges 12, functions as keyway to hold the "key" edges 12
in close coupling and, resultingly, the stabilizer 10 in con-
tracted position. Now then, the stabilizer 10, for having a
cross-sectional or transverse dimension slightly less than
the earth structure bore in which to be installed, can be
freely and slidably fitted therein. Upon the contracted stab-
ilizer 10 being installed into the bore, it can be relaxed to
return toward its free, transverse dimension. To accommodate
for this, the contraction or clamping device 20 has an a
aperture 22, formed through the lower end, which may be
grasped by a tool. Simply by slidably withdrawing the device
20, it comes free of the stabilizer 10, and the latter expands
outwardly to engage the bore wall.
In U.S. Patent ~o. 4,012,913, patentee Scott set
forth an alternative embodiment of his friction rock stabilizer
in which the edges of the slit therein are or may be overlapped.
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In Figures 3 and 4 I disclose an alternative embodiment
lOa of a stabilizer according to the invention, drawn on the
type of stabilizer depicted in said patent 4,012,913. Herein I
turn the edges 12a and 12b of the "overlapped" slit 14a in oppo-
site directions so that the edges define parallel and confrontingribs~ Then by inserting a spacer blade 2~ therebetween, the rib-
defining edges 12a and 12b are forced apart, resulting in a con-
traction of the stabilizer lOa. ~gain, following earth structure
bore insertion of the thereby contracted stabilizer lOa, it re-
mains only to withdraw the blade 24, by means of the tool-aper-
ture 22a, to allow the confronting edges 12a and 12b to close to-
ward each other, so that the stabilizer lOa might return towards
its free dimension.
Corrosive mine environments pose serious problems and,
lS as a consequence, it is frequently deemed advisable to apply a
corrosion-protective coating to the stabilizers 10 and lOa. How-
ever, the prior art-practiced method of installing stabilizers
into undersized bores, by applying the considerable and necessary
thrusting force, destroys any stabilizer coatings. The wall of
the bore simply scrapes off the coated surface. It is for this
reason that my novel method of stabilizer insertion is particu-
larly beneficial. The coated stabilizer is contracted to a di-
mension of less than that of the bore, so that the bore will not
have any significant, abrasive contact with the coating during
stabilizer insertion. Then, the stabilizer is merely allowed to
expand, and the coating closes into an undisturbed contact with
the bsre wall.
To m~y attention has come Republic of South A-frica
~R.S.A.) patent specification Mo. 7~/5306 which has published in
the RoS~A~ Patent Journal of August 1979.
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The R.S.A. specification recites a method of inserting a "friction
roof bolt" in a hole in a roof or side wall of an underground
opening for anchoring the roof or side wall, said bolt compris-
ing a generally annular body from end-to-end having a slot through
its ~hickness and being arranged to permit radial compression,
wherein a hole is formed in the roof or side wall having a dia-
meter which is smaller than that of said body when the body is in
a noncompressed state, characterized by the steps of radially
compressing said body to a diameter somewhat smaller than the
diameter of the hole, fixing said body in the compressed state,
inserting the compressed body in the hole, and causing the body
to expand to engage the surrounding wall of the hole upon being
inserted in the hole.
The aforesaid R.S.A. defines a method not too dissimilar
to my inventive method which comprises inserting a friction rock
stabilizer in a bore formed in an earth structure, for stabiliz-
ing the structure, wherein the bore has a given transverse dimen-
sion, and the stabilizer has a first, free, relaxed, transverse
dimension which is greater than said given dimension and is
resiliently contractible to a second, constrained, transverse
dimension which is slightly less than said given dimension of
said bore, comprising the steps of slidably engaging the stabi-
lizer with a device to cause contraction of the stabilizer to
said second, constrained, transverse dimension; inserting the
contracted s~abilizer into the bore; and disengaging the device
to permit a release of the stabilizer from its contracted con-
straint.
The R.S.A. method and my own differ in at least one,
material respect, however. My method comprises the slidable
engagement of the stabilizer with a contracting device 20 and,
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patently offers a facile method of contracting the bore-
inserted stabilizer again, subsequently, for withdrawal there-
of from a bore. It lS frequently desirable to remove a bore-
inserted stabilizer to study the effects of corrosion, abra-
sion etc. visited on the stabilizer. ~ence, my method owns
this desirable reversibility. The R.S.A.-disclosed method
comprises an irreversible stabilizer insertion as, in the
embodiments thereof, it requires the severing of constraining
bands following insertion. After the bands have been severed,
no way is offered for again contracting the stabilizer to per-
mit its removal from a bore.
While I have described my invention in connection with
specific embodiments thereof, and methods of practice, it is
to be clearly understood that this is done only by way of
example, and not as a limitation to the scope of my inYention
as set forth in the objects thereof and in the appended claims.
