U.S. patent application number 13/125623 was filed with the patent office on 2011-09-15 for mine support grout packs.
Invention is credited to Nils Mittet Skarbovig.
Application Number | 20110222970 13/125623 |
Document ID | / |
Family ID | 42232929 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110222970 |
Kind Code |
A1 |
Skarbovig; Nils Mittet |
September 15, 2011 |
MINE SUPPORT GROUT PACKS
Abstract
A grout pack is provided comprising a grout bag and a
restraining envelope encircling the grout bag. The restraining
envelope includes multiple elongate tension elements made of a
multitude of fibres twisted, braided or woven to form confinement
tension elements for operatively supporting the grout bag. The
restraining envelope may include an inner mesh layer positioned on
the inside of the elongate tension elements which may assume the
form of containment rings encircling the grout bag at spaced
positions up the height of the grout pack. Alternatively, or in
addition, at least some elongate tension elements may extend in
generally helical directions of opposite hand in the installed
condition of the grout pack. The tension element may assume the
form of a rope or a length of webbing. The ends of the rope or
webbing may be joined in a manner providing for controlled slipping
of overlapping ends thereof.
Inventors: |
Skarbovig; Nils Mittet;
(Vredenburg, ZA) |
Family ID: |
42232929 |
Appl. No.: |
13/125623 |
Filed: |
November 3, 2009 |
PCT Filed: |
November 3, 2009 |
PCT NO: |
PCT/IB09/07299 |
371 Date: |
April 22, 2011 |
Current U.S.
Class: |
405/289 |
Current CPC
Class: |
E21D 15/483
20130101 |
Class at
Publication: |
405/289 |
International
Class: |
E21D 15/32 20060101
E21D015/32 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2008 |
ZA |
2008/10305 |
Claims
1. A grout pack comprising a grout bag and a restraining envelope
encircling the grout bag, the grout bag having flexible side walls
and two ends defining, in use, a top, and a bottom and a cavity for
receiving settable granular material or grout, the grout bag
further having an inlet for slurry to be introduced into the
interior of the grout bag and wherein the flexible side walls are
adapted to retain solids within the grout bag and the grout bag has
an axis in the general direction of which a filled and set grout
pack is adapted to yield, wherein the restraining envelope includes
multiple elongate tension elements each of which is made of a
multitude of fibres twisted, braided or woven or any combination
thereof to form confinement tension elements for operatively
supporting the grout bag.
2. A grout pack as claimed in claim 1 in which the fibres are
polymer fibres selected from one or more of polypropylene, nylon,
polyesters, polyethylene and aromatic polyamides.
3. A grout pack as claimed in claim 1 in which the restraining
envelope includes an inner mesh layer positioned on the inside of
the elongate tension elements.
4. A grout pack as claimed in claim 1 in which at least some
elongate tension elements assume the form of containment rings
encircling the grout bag at spaced positions up the height of the
grout pack in the installed condition.
5. A grout pack as claimed in claim 1 in which at least some
elongate tension elements extend in generally helical directions of
opposite hand in the installed condition of the grout pack.
6. A grout pack as claimed in claim 1 in which the restraining
envelope includes terminal rigid confinement rings at each of its
two ends.
7. A grout pack as claimed in claim 1 in which a tension element
assumes the form of a rope (8, 10).
8. A grout pack as claimed in claim 7 in which the ends of a length
of rope are spliced together to form an endless loop.
9. A grout pack as claimed in claim 8 in which the splice is
configured to be either a non-slip type of splice or a splice
configured to slip under predetermined loads in order to provide
for controlled yielding of an installed grout pack.
10. A grout pack as claimed in claim 1 in which a tension element
assumes the form of a length of webbing.
11. A grout pack as claimed in claim 10 in which the free ends of a
length of webbing are associated with a buckle that is arranged to
provide for yielding under predetermined loads.
12. A grout pack as claimed in claim 10 in which selected
overlapping zones of the webbing are stitched together.
13. A restraining envelope adapted to receive a grout bag in order
to form a grout pack as claimed in claim 1.
Description
FIELD OF THE INVENTION
[0001] This invention relates to mine support grout packs of the
type having a grout bag that, in use, is filled with a cementitious
or other settable mix, typically, but not necessarily, including
pulverised ore or backfill of processed or barren mined
material.
[0002] The term grout bag as used herein is intended to mean a
generally permeable bag that is used to contain slurry pumped into
it under pressure and to retain the solids whilst allowing excess
moisture to permeate through the grout bag wall that is typically
made of a suitable textile material such as a geotextile
material.
[0003] The term grout pack as used herein is intended to mean a
grout bag that is used in combination with a restraining envelope
encircling the generally upright walls of the grout bag, the
restraining envelope including either or both of a reinforcing mesh
and a series of elongate tension elements typically in the form of
confinement rings or bands encircling the grout bag.
BACKGROUND TO THE INVENTION
[0004] Depending on the type and quality of rock being supported,
the depth of mining, the prevalent field stresses, seismicity,
stoping width and a number of other factors, stope support can
utilise a vast range of materials, configurations and systems,
including, gum poles, timber and composite packs, steel props,
unmined ore pillars, rock anchors and granular (tailings) type
supports.
[0005] Among the granular support media, cemented grout packs are
increasingly being utilized as combination support products,
consisting essentially of a support column formed by cured cemented
backfill or a similar cured cementitious grout, contained within a
geotextile bag and stiffened against lateral deformation under
axial load with an external restraining envelope of either or both
of a reinforcing mesh and a series of tension rings or bands
encircling the grout bag, typically both.
[0006] In a conventional configuration, a non-yielding type of
grout pack consists of a grout bag surrounded by a restraining
envelope including some form of mesh reinforcement and a plurality
of confinement rings encircling the mesh and bag. In the instance
of yielding grout packs, the construction is similar except that
the confinement rings or ring assemblies are able to yield under
load thereby maintaining a measure of restraining force before
their eventual failure. The mesh is typically a reinforcement of
wire or polymer netting and the confinement rings are usually made
of steel wire.
[0007] Also, due to its relative rigidity, steel wire requires
relatively complex production facilities for making the confinement
rings. Also, the yielding characteristics of steel wire may not be
appropriate as regards the yielding behaviour of the confinement
rings.
OBJECT OF THE INVENTION
[0008] It is an object of this invention to provide a grout pack
having an alternative restraining envelope that is suitable for
ease of production and to provide for controlled collapse of an
installed grout pack in use.
SUMMARY OF THE INVENTION
[0009] In accordance with one aspect of this invention there is
provided a grout pack comprising a grout bag and a restraining
envelope encircling the grout bag, the grout bag having flexible
side walls and two ends defining, in use, a top, and a bottom and a
cavity for receiving settable granular material or grout, the grout
bag further having an inlet for slurry to be introduced into the
interior of the grout bag and wherein the flexible side walls are
adapted to retain solids within the grout bag and the grout bag has
an axis in the general direction of which a filled and set grout
pack is adapted to yield, the grout pack being characterised in
that the restraining envelope includes multiple elongate tension
elements each of which is made of a multitude of fibres twisted,
braided or woven or any combination thereof to form confinement
tension elements for operatively supporting the grout bag.
[0010] Further features of the invention provide for the fibres to
be polymer fibres including but not limited to one or more of
polypropylene, nylon, polyesters, polyethylene especially high
molecular weight polyethylene, and aromatic polyamides; for the
restraining envelope to include an inner mesh layer positioned on
the inside of the elongate tension elements; for the elongate
tension elements to assume the form of containment rings encircling
the grout bag at spaced positions up the height of the grout pack
in the installed condition; or, alternatively, for the elongate
tension elements to extend in generally helical directions of
opposite hand in the installed condition of the grout pack; and for
the restraining envelope to include terminal rigid confinement
rings at each of its two ends, the rigid confinement rings
conveniently being of steel wire or similar relatively rigid
material.
[0011] In one variation of the invention each tension element
assumes the form of a rope that may be of a twisted construction or
a braided construction. In such variation the ends of a length of
rope are preferably spliced together to form an endless loop. The
splice may be either configured to be a non-slip type of splice or
it may be configured to slip under predetermined loads in order to
provide for controlled yielding of an installed grout pack.
[0012] In another variation of the invention each tension element
assumes the form of a length of webbing. In such an instance the
free ends of a length of webbing may be stitched together to form
an endless loop. Alternatively, the free ends of a thing of webbing
may be associated with a buckle that may be arranged to provide for
yielding under predetermined loads. In the event that the webbing
is arranged in a criss-cross arrangement, the overlapping zones of
the webbing can be stitched together.
[0013] The invention also provides a restraining envelope adapted
to receive a grout bag in order to form a grout pack as defined
above.
[0014] As a general rule, the grout packs defined above are
preassembled at a factory level for transport, storage and
conveyance to a site of installation in a collapsed condition with
the grout pack being ready for installation and erection by
securing the upper portion of the assembly against the stope
hanging wall and filling the grout bag with a suitable settable
material that is typically a cementitious material introduced in
the form of a slurry.
[0015] In order that the above and other features of the invention
may be more fully understood, various embodiments of the invention
will now be described with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the drawings:--
[0017] FIG. 1 is a schematic elevation of one embodiment of grout
pack according to the invention in an operative position between a
hanging wall and a footwall;
[0018] FIG. 2 is a schematic plan view thereof; and,
[0019] FIGS. 3, 4, 5, 6, 7, 8 and 9 are each a schematic elevation
of a second, third, fourth, fifth, sixth, seventh and eighth
embodiment of grout pack according to the invention.
DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS
[0020] In the embodiment of the invention illustrated in FIGS. 1
and 2, a grout bag (1) has, in an operative inflated condition,
generally cylindrical flexible side walls (2), and two end walls
that form a top (3), and a bottom (4) so as to define a cavity for
receiving settable granular material or grout as shown in the
cut-away part of FIG. 1 and as indicated by numeral (5). A
non-return inlet valve (6) is provided for the introduction of
granular material or grout in the form of slurry that is to be
introduced into the cavity of the grout bag, in the usual way.
[0021] The grout bag may be manufactured from a series of panels
stitched together or it may be made from a tubular textile material
having end panels secured thereto of the required shape defining
the top and bottom.
[0022] The fabric from which the grout bag is manufactured may be
any suitable fabric and, in particular, a geotextile is considered
to be particularly suitable, at least for the flexible side walls
that are adapted to retain solids within the grout bag and allow
water to permeate through it as may be required. A similar result
can be achieved in numerous different ways and utilising numerous
different designs.
[0023] In this particular embodiment of the invention a grout pack
is formed utilising the grout bag described above together with a
restraining envelope comprising both an inner peripheral supporting
mesh (7) conforming generally to the outer shape of the grout bag
in the open condition and a series of operatively axially spaced
circumferential confinement rings (8), the axis being indicated by
line A-A in FIG. 1.
[0024] In keeping with this invention, each of the confinement
rings (8) is formed from a synthetic polymer rope made of a
multitude of polymer fibres twisted or braided together to form the
rope. The free ends of a suitable cut length of rope are joined
together by means of a splice indicated by numeral (9) to form an
endless loop. The splice can be configured in one of two different
ways.
[0025] In a first way the splice is made to be non-slipping and a
permanent connection between the two ends. In such an event
yielding is dependent on the stretch available in the rope and the
rope will eventually break at some point that will generally not be
the splice.
[0026] In a second way the splice is configured such that when a
predetermined tension is exerted on the splice in consequence of
the grout pack yielding, the splice slips to allow the containment
ring to increase in size whilst still retaining effective
containment of the collapsing grout pack. In such an event the
confinement ring will eventually fail once the splice has slipped
sufficiently to cause the splice to effectively open.
[0027] In the embodiment of the invention illustrated in FIG. 1 the
confinement rings are spaced equally up the height of the grout
pack in the installed condition and are arranged to extend
substantially circumferentially around the grout pack.
[0028] In the second embodiment of the invention that is
illustrated in FIG. 3, the restraining envelope is devoid of any
conventional mesh and comprises multiple elongate tension elements
in the form of helically wound synthetic polymer ropes (10)
extending in generally helical directions of opposite hand in the
installed condition of the grout pack. In this embodiment of the
invention the ropes extend at about 45.degree. to the horizontal
and are themselves interlaced to form a coarse mesh with diamond
shaped apertures, as illustrated in FIG. 3. The ropes are attached
at each end to a steel wire ring (11) of generally conventional
configuration at the top and bottom of the grout pack. The
individual ropes may include splice joints (12) made in either of
the first and second ways described above.
[0029] In the embodiment of the invention illustrated in FIG. 4,
the rope is replaced by tension elements in the form of interlaced
helically wound webbing (15) and the steel wire rings are replaced
by circumferential rings (16) of webbing to which the ends of the
helically wound webbing are secured by stitching (17) at the angle
of 45.degree.. Once more the restraining envelope is devoid of any
conventional restraining mesh.
[0030] In the embodiment of the invention illustrated in FIG. 5,
the elongate tension elements (18) are, once more, webbing. The
webbing is wound in more horizontal helices that make an angle of
about 22.5.degree. with the horizontal or 67.5.degree. with the
direction of the axis of the grout pack. This flatter direction in
which the webbing is wound translates into tension elements that
carry a higher tensile load than in the instance of the embodiment
illustrated in FIG. 4 with the result that the grout pack will show
a stiffer response under compressive load, in use.
[0031] In the embodiment of the invention illustrated in FIG. 6,
the restraining envelope has both an inner peripheral supporting
mesh (20) of generally conventional design conforming to the outer
shape of the grout bag in the open condition and a series of
operatively axially spaced elongate tension elements in the form of
spaced circumferential confinement rings (21) that in this instance
are made of webbing. The ends of the webbing can be stitched
together as indicated by numeral (22) and at least selected
confinement rings can be provided with buckles (23) that are
configured to allow controlled slippage of overlapped end regions
of the webbing to enable the circumference thereof to increase and
provide a yielding characteristic. The top and bottom rings (24)
can conveniently be generally conventional steel rings, as
described with reference to FIG. 3. The ends of both the mesh and
bag are secured to the steel rings.
[0032] In the embodiment of the invention illustrated in FIG. 7,
the arrangement is the same as that described with reference to
FIG. 6 apart from the fact that additional longitudinally extending
tension elements in the form of lengths of webbing (26) extend in a
direction parallel to the axis of the grout pack between the upper
and lower steel rings (27).
[0033] In the embodiment of the invention illustrated in FIG. 8 the
arrangement is substantially the same as that described reference
to FIG. 4 except that selected lengths of the helically wound
webbing tension elements (30) are provided with buckles (31) that
are configured to allow controlled slippage of overlapped end
regions of the webbing to enable the length thereof to increase and
provide a yielding characteristic under load. Also, FIG. 8
illustrates the fact that two layers of webbing can be stitched
together at selected points at which lengths of webbing cross each
other, as indicated by numeral (32). In the embodiment of the
invention described with reference to FIG. 8, the ends of the
restraining envelope are once more steel rings (33).
[0034] In the embodiment of the invention illustrated in FIG. 9,
the arrangement is substantially the same apart from the fact that
the webbing tension elements (35) extend at a flatter angle to the
horizontal as in the case of the embodiment described with
reference to FIG. 5.
[0035] Numerous variations may be made to the embodiments of the
invention described above without departing from the scope hereof.
In particular, it should be noted that the construction of the
elongate tension members can be varied widely and is not limited to
any of those described above. Also, wherever a steel ring is used,
this may be a double steel ring to facilitate attachment of any
mesh that may be used and any elongate tension members to it. Also,
any other type of fastening of the elongate tension members to each
other or to an end confinement ring may be employed.
[0036] Numerous other arrangements are possible within the scope of
the invention.
* * * * *