FIELD OF THE INVENTION
[0001] The invention relates to an apparatus for grouting a rock anchor in a rock hole.
BACKGROUND OF INVENTION
[0002] Grouting of a rock anchor within a rock hole is a difficult and messy affair.
[0003] Typically, a grout conduit connected to a grout source needs to be attached to a
grout pipe that projects from the rock hole. The problem is that the rock anchor installation
is often at a height that is not easily reached. Moreover, there is a need for a connector
to connect a nozzle end of the grout conduit to the grout pipe to ensure a sealed
connection to prevent grout outflow from the connection interface.
[0004] Also, in such an installation, the mouth of the rock hole needs to be sealed from
grout egress once the rock hole is filled with grout. Therefore, in a typical grouted
rock anchor installation, there are many points at which the grout can leak.
[0005] The invention at least partially solves the aforementioned problems.
SUMMARY OF INVENTION
[0006] A rock anchor assembly is provided by the invention which includes a rock anchor
comprising a flexible element and a first and a second cylindrical connector element
engaged to a proximal end portion and a distal end portion respectively of the element,
a tubular sleeve, made at least of a flexible material that longitudinally extends
between a first end and a second end, on the rock anchor such that end parts of the
rock anchor project from the first and second ends respectively of the sleeve; a load
bearing barrel which is centrally bored to engage the first connector element between
the first end of the sleeve and a proximal end of the rock anchor, which barrel is
adapted to engage with the first end of the sleeve in sealing contact, and which barrel
has at least one grout conduit between an exterior surface of the barrel and the bore,
which at least one conduit defines a part of a grout passage which communicates the
exterior surface of the barrel with an interior of the sleeve, when the barrel is
engaged with the sleeve; a seal which seals the grout passage to grout outflow but
accommodates inflow of grout from a source; a tensioning means engaged with the first
tubular connector element between the proximal end of the rock anchor and the barrel,
and a mechanical anchor engaged with the second tubular connector.
[0007] The flexible element may be a length of cable manufactured from steel or a composite
material.
[0008] The connector elements may be made of a steel or composite material.
[0009] Each steel connector element may be swaged onto the respective proximal and distal
end portions of the cable.
[0010] The sleeve may have a flared end section which opens onto the first end and an anchor
housing section which opens onto the second end.
[0011] The load bearing barrel may be comprised of a solid body of a suitable metal material
which has a domed or conical forward end and an opposed back end.
[0012] The barrel may have a plurality of grout conduits. The plurality of grout passages
may be evenly radially spaced about the body.
[0013] The tensioning means maybe a nut threaded onto complementary threads formed on the
first tubular connector.
[0014] The assembly may include a tubular spacer on the rock anchor between the first end
of the sleeve and the forward end of the barrel or between the back end of the barrel
and the tensioning means.
[0015] The tubular spacer may be made of a suitable plastics material which deforms or breaks
when a compressive force is applied to it to collapse or break away from the rock
anchor, allowing the rock anchor to move longitudinally relatively to the sleeve between
a first position and a second position.
[0016] The mechanical anchor may be at least partially received within the anchor housing
section of the sleeve in an unexpanded configuration when the rock anchor is in the
first position.
[0017] The mechanical anchor may move from the sleeve into an expanded configuration when
the rock anchor is in the second position.
[0018] The assembly may include a grout delivery coupling member which includes a body with
a member first end and a member second end and a passage between the ends, a circular
distributing channel in a wall of the passage and a grout inlet port in a side of
the member which communicates an exterior of the member with the channel, wherein
the passage is adapted to at least partially receive the barrel from the member first
end and to engage with the barrel in a position in which the at least one grout conduit
of the barrel sealingly docks with the channel.
[0019] The coupling member may engage with the barrel in a twist-lock manner.
[0020] The barrel, alternatively the coupling member, may have a plurality of bayonet type
projections which engage with complementary slots or recesses on the coupling member,
alternatively the barrel.
[0021] A grouting kit for grouting a rock anchor in a rock hole which includes a load bearing
barrel which is centrally bored to engage with the rock anchor and which has at least
one grout conduit between an exterior surface of the barrel and the bore and a seal
which seals the grout conduit, and a grout delivery coupling member which includes
a body with a first end and a second end and a passage between the ends, a circular
distributing channel in a wall of the cylindrical passage and a grout inlet port in
a side of the member which communicates an exterior of the member with the channel,
wherein the passage is adapted to receive the barrel from the first end and to engage
with the barrel in a position in which the at least one grout conduit sealingly docks
with the channel.
[0022] The load bearing barrel may be comprised of a solid body of a suitable metal material
which has a domed or conical forward end and an opposed back end.
[0023] The barrel may have a plurality of grout conduits. The plurality of grout passages
may be evenly radially spaced about the body.
[0024] The coupling member may engage with the barrel in a twist-lock manner.
[0025] The barrel, alternatively the coupling member, may have a plurality of bayonet type
projections which engage with complementary slots or recesses on the coupling member,
alternatively the barrel.
[0026] The invention provides a method of anchoring a rock anchor assembly within a rock
hole, the rock anchor assembly including a flexible outer sleeve which extends between
a first end and a second end opening; a rock anchor which locates, at least partially,
within the sleeve such that end parts of the rock anchor extend beyond the first end
and the second end of the sleeve, the rock anchor comprising a flexible cable and
a first and a second cylindrical connector element engaged to a proximal end portion
and a distal end portion respectively of the cable; with the first cylindrical connector
element carrying a mechanical anchor which is at least partly held within the sleeve
in a closed position and the second cylindrical connector element being at least partly
threaded; a faceplate located over the sleeve; a barrel on the threads of the second
connector element and a fastener on the threads between the barrel and a proximal
end of the rock anchor; the method including the steps of pre-spacing the barrel from
the first end or the pre-spacing of the fastener from the barrel; inserting the rock
anchor assembly into a predrilled rock hole, a distal end of the rock anchor leading,
until the faceplate is sandwiched between rock wall and the sleeve or the barrel and
pushing the anchor further into the rock hole to close the pre-spacing allowing the
rock anchor to move relatively to the sleeve to drive the mechanical anchor from the
first end of the sleeve and into a radially expansive open position in which the mechanical
anchor resistively engages the walls of the rock hole.
[0027] The pre-spacing of the barrel from the first end of the sleeve or the pre-spacing
of the fastener from the barrel may be achieved with a tubular spacer which locates
on the cable anchor, between the first end of the sleeve and barrel or between the
barrel and the fastener.
[0028] The tubular spacer may be made of a suitable plastics material which deforms or breaks
when a force pushing the anchor further into the hole reaches a predetermined level.
[0029] To introduce a grout into the rock hole, the method may include the additional steps
of engaging a coupling device to the barrel and pumping a grout material from a source
through the coupling device and at least one channel provided in a sidewall of the
barrel, into an annular space between the sleeve and the cable and, eventually, into
an annular space between the sleeve and walls of the rock hole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention is described with reference to the following drawings in which:
Figure 1 illustrates a view in elevation of a rock anchor assembly in accordance with
a first embodiment of the invention;
Figures 2A and 2B illustrate a longitudinal section through the rock anchor assembly
of Figure 1.
Figure 2C and 2D illustrate longitudinal sections through the rock anchor assembly,
showing a different engagement of a sleeve and a barrel of the assembly;
Figures 3A and 3B isometrically illustrate the assembly of Figures 2A and 2B;
Figure 4 isometrically illustrates the rock anchor assembly, partially pie-sectioned;
Figures 5A and 5B isometrically illustrate, in partial section, a first embodiment
of a barrel and a coupling member assembly which attaches to the rock anchor assembly;
Figure 6 is an isometric illustration of a circular spacing ring which is included
in the coupling member illustrated in Figures 5A and 5B;
Figures 7A to 7C diagrammatically and sequentially illustrate the rock anchor assembly
of either embodiment with a tubular spacer being inserted into a rock hole in a method
of the invention;
Figure 8 illustrates a longitudinal section through a rock anchor assembly in accordance
with a second embodiment of the invention; and
Figure 9 isometrically illustrates, in longitudinal section, the rock anchor assembly
of Figure 8.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] Referring to Figures 1 to 4 of the accompanying drawings, a rock anchor assembly
10 is provided.
[0032] With reference to Figures 2A and 2B, the assembly includes a rock anchor which comprises
a length of flexible high tensile cable 12, of a steel or composite material, which
extends between a distal end 16 and a proximal end, 18. The anchor has a first and
a second tubular metal connector element, respectively designated 14A and 14B, each
of which is swaged onto a respective end section of the cable by employing a radial
swaging method.
[0033] It is also anticipated within the scope of this invention that the connector elements
14 can be made of a composite material which is bonded to the cable by any suitable
technique.
[0034] The first connector element 14A is, at least, partially externally threaded with
a threaded section 20. A mechanical anchor 22 locates on the second connector element,
towards the distal end 16 of the cable. The mechanical anchor is a standard expansion
shell type anchor.
[0035] The assembly 10 includes an elongate tubular sleeve 24 made of a flexible material
such as LDPE, HDPE or polypropylene. Although the material of the sleeve is inherently
flexible, increased flexibility is introduced by forming the sleeve with a plurality
of relatively flexible sections 24.1 interspersed with relatively inflexible sections
24.2. This provides a corrugated outer surface which aids in providing purchase to
a grout column in use.
[0036] Referring to Figures 2A and 2B, the sleeve extends between a first end 26 and a second
end 28. At one end, the sleeve flares into a flared end section 30 which opens on
the first end 26. The sleeve also slightly flares at the opposed end, opening onto
the second end 28. This slightly flared formation provides an anchor housing section
31. In one alternative, the flared end sections can be integrally formed with the
remainder of the sleeve. In another, the sections can be separately made, from a metal
material, and riveted to the sleeve.
[0037] The connector elements 14A and 14B of this embodiment are metal studs with a bore
60 that longitudinally extends only partially through each stud. The distal and proximal
ends (16, 18) of the cable are inserted into the bore, in the manufacture of the rock
anchor component, the proximal and distal end portions of the cable are fixed within
the respective connector element by employing a radial swaging technique.
[0038] Figures 8 and 9 illustrate a second embodiment of the invention. In this embodiment,
the rock anchor assembly 10A has a rock anchor component which comprises the cable
12 and a first and second connector element (14A and 14B). However, the essential
difference between this embodiment and the earlier embodiment (10) is the connector
elements are not tubular and the cable does not extend through the element from end
to end as is illustrated in Figures 2A to 2D.
[0039] The sleeve is adapted to receive the cable anchor with a distal end and a proximal
end part (16, 18) of the anchor extending beyond the first end and second ends (26,
28) respectively of the sleeve. The sleeve is held in position on the cable by frictional
engagement with the anchor 22 which is at least partially received in the anchor housing
section 31 of the sleeve as illustrated in Figure 2A.
[0040] The assembly (10 and 10B) includes a faceplate 32 which as shown in Figures 2A and
2B, rests on an outer surface of the flared end section 30. The sleeve 24 is engaged
with the faceplate by passage through a central aperture 34 (see Figure 2C) of the
plate.
[0041] As best illustrated in Figures 5A and 5B, the assembly (10 and 10B) further includes
a barrel 36 comprised of a solid barrel-shaped metal body 38. The body 38 has a domed
end 42 and a trailing end 44 with a central bore 46 extending between the ends. In
a sidewall of the barrel, a plurality of grout conduits 48 are formed (only one is
illustrated in the Figures), uniformly radially spaced, communicating an exterior
of the barrel with the bore 46.
[0042] The rock anchor is passed through the barrel's central bore 46, from the cable's
proximal end 18, to locate on the threaded section 20 of the first connector element
14A. This is best illustrated in Figure 4. To hold the barrel 36 in position on the
threaded section, initially spaced from the flared end section 30 of the sleeve 24,
a nut 50 is threaded onto the threaded section 20 to eventually contact the trailing
end 44 of the barrel's body. A load indicating washer 52 can be interposed between
the nut 50 and the trailing end 44 to indicate when load on the barrel has reached
a predetermined level.
[0043] Prior to grouting and with the rock anchor received in the sleeve 24 and the faceplate
32 and barrel 30 pre-attached as described, the rock assembly (10 and 10B) is inserted
into a pre-drilled rock hole 54 with the distal end 16 of the cable leading. In this
pre-configuration, the anchor housing section 31 of the sleeve at least partially
covers the mechanical anchor 22, as illustrated in Figure 2A, to retain the anchor
in a closed unexpanded position.
[0044] When the faceplate 32 comes into contact with the hanging wall 56 the sleeve 24 is
prevented from further passage into the rock hole by the flared end section 30 making
contact with the faceplate. However, the cable 12 is capable of further movement,
axially inwardly relatively to the sleeve, as illustrated in Figure 2B. The cable
is rigid enough to be pushed in the axial direction without buckling. This pushing
movement forces the mechanical anchor 22 from the confines of the sleeve allowing
the anchor to radially expand under spring action into frictional engagement with
the surrounding walls of the rock hole 54. The mechanical anchor will thus secure
the rock anchor assembly within the rock hole about the second tubular connector element
14B.
[0045] Upward movement of the rock bolt also will cause the domed end 40 of the barrel 36
to come into sealing contact with an inside of the flared end section 30. This is
as illustrated in Figure 2B. The nut 50 can now be tightened against the barrel to
bring about load bearing contact of the barrel with the flared end section of the
sleeve. The assembly 10 is now ready to be grouted.
[0046] An alternative to the flaring of the sleeve, to provide sealing engagement of the
sleeve and the barrel, is illustrated in Figures 2C and 2D. In this variation the
sleeve is without a flared end. The first end 26 of the sleeve inserts within the
bore 46 of the barrel, sealingly abutting an annular ridge 56 on an inside surface
of the bore of the barrel.
[0047] To enable grouting of the assembly 10, a coupling member 58 is provided. The coupling
member 58 includes a body 60 which extends between a first end 62 and an opposed second
end 64. The body defines a cylindrical passage 65 which extends between the ends.
[0048] In an inner wall of the cylindrical passage 65, a circular distributing channel 68
is formed. The channel is disposed towards the first end 62. A hole penetrates the
channel which leads into a corresponding side projecting inlet port 70. The inlet
port is adapted to attach to a grout delivery from a hose (not shown). The port thus
communicates with the bore 46 via the hole, the channel and the conduit 48.
[0049] Below the channel 68, towards the second end 64, the cylindrical passage is formed
with a locking formation 72 which receives complementary bayonet formations 74 (see
Figure 3A) in twist lock engagement as more fully described below. The bayonet formation
laterally extends from an outer surface of the barrel 36 towards the trailing end
44 of said barrel.
[0050] On a floor and a roof surface (respectively designated 76 and 78 on Figure 4) of
the channel 68, a respective circular sealing formation 80 is provided, held apart
by a spacing ring 82 (see Figure 6). Apertures 83 of the ring allow the passage of
grout as will be explained more fully below.
[0051] The coupling member 58 is to be attached to the barrel 36 so that grout, from a source
(not shown), can be delivered through the barrel and into the sleeve. Firstly, the
grout delivery hose is pre-attached to the inlet port. Secondly, an elevating shaft
(not shown) is connected, at one end, to the second end 64 of the coupling member
by, for example, receiving the second end within a complimentary shaped recess in
the end of the lance. Thereafter, the coupling member 58 is elevated on the shaft
and presented to a barrel engaged end of the pre-installed rock anchor assembly 10,
the first end 62 of the member leading.
[0052] The barrel 36 is then partially received into the cylindrical passage 65 from the
first end 62 and engaged with the coupling member 58 within the passage. Engagement
is achieved by twisting the coupling member relatively to the barrel to receive the
bayonet formation 74 of the barrel within the locking formation 72.
[0053] Locked within the passage, the barrel is positioned such that each of the grout conduits
48 is in planar alignment with the circular distribution channel 68. The opposed sealing
formations 80 in the channel seal the docking engagement of the grout conduits with
the distributing channel.
[0054] Grout can now be pumped through the grout delivery hose for delivery to the inlet
port 70, through the side hole 69 and into the grout distributing channel 68. In the
channel, grout is circumferentially distributed about the barrel for entry into the
central bore 46 through each of the plurality of grout conduits 48. Grout egress from
points of contact of the barrel with the coupling member 58 is prevented by the sealing
formations 80 which sandwich the channel.
[0055] Flowing from the grout conduits 48, the grout passes a band seal 84 which is caused
to move away from an exit of each grout conduits to allow the grout to flow into an
interior of the sleeve 24 via the bore 46. Within the sleeve, about the cable 12,
the grout percolates upwardly until reaching the first end 24 of the sleeve, at which
point the grout cascades downwardly into the annular space between the sleeve and
the rock-hole walls.
[0056] Grout is prevented from flowing back into the grout conduits 48 by the band seal
84 which is forced back against the exits of the grout conduits.
[0057] Thus, with the grouting of the rock anchor assembly 10, the cable 12 is grouted within
the sleeve 24 which, in turn, is grouted within the rock hole.
[0058] The barrel 36 and the coupling member do not need to have means to inter-engage.
It is also anticipated that the coupling member can be held in place, over the barrel,
by an external installation machine or tool.
[0059] Figure 7 illustrates use of the rock bolt assembly (10A and 10B) which has a tubular
spacer 55 made of a suitable plastics material. The spacer 55 provides a suitable
offset space (designated 92 on Figures 9A and 9C) equivalent to the distance of longitudinal
travel (also designated 92 on Figure 9C) that is required of the cable 12 relatively
to the sleeve 24, once in the assembly is in the rock hole, to move the mechanical
anchor 22 from the confines of the sleeve so that it can radially expand into frictional
engagement with the rock hole walls.
[0060] Once installed, a further inwardly directed force on the rock bolt 14 by, for example,
the installation machine (not shown) will be taken up by the sleeve 55 which will
eventually collapse or break away at a pre-defined load point. This is illustrated
in Figure 8C.
[0061] With relative longitudinal movement of the cable 12 relatively to the sleeve 24 no
longer prevented by the collapsed or moved spacer 55, the cable moves inwardly relatively
to the sleeve and, in so doing, the nested mechanical anchor 22 is pushed from the
confines of the sleeve. Unconfined, the mechanical anchor radially expands under spring
biasing action.
[0062] The tubular spacer 55 is pre-installed to provide a complete unit of the assembly
(10A and 10B) and is sandwiched, in this example, between the trailing end 44 of the
barrel 36 and the nut 50.
[0063] The flexibility of the cable 12 and the sleeve 24 allow the assembly (10A and 10B)
to be bent sufficiently to allow installation in a narrow stope environment, whilst
maintaining all the benefits of the rock bolt assembly of the parent specification
i.e. a means of efficient and clean introduction of a grout into the rock hole to
grout the rock anchor, a means of mechanically anchoring the rock anchor into the
hole before grouting and an improved static load carrying capacity.
1. A rock anchor assembly which includes a rock anchor comprising a flexible element
and a first and a second cylindrical connector element engaged to a proximal end portion
and a distal end portion respectively of the element; a tubular sleeve, made at least
of a flexible material that longitudinally extends between a first end and a second
end, on the rock anchor such that end parts of the rock anchor project from the first
and second ends respectively of the sleeve; a load bearing barrel which is centrally
bored to engage the first connector element between the first end of the sleeve and
a proximal end of the rock anchor, which barrel is adapted to engage with the first
end of the sleeve in sealing contact, and which barrel has at least one grout conduit
between an exterior surface of the barrel and the bore, which at least one conduit
defines a part of a grout passage which communicates the exterior surface of the barrel
with an interior of the sleeve, when the barrel is sealingly engaged with the sleeve;
a seal which seals the grout passage to grout outflow but accommodates inflow of grout
from a source; a tensioning means engaged with the first tubular connector element
between the proximal end of the rock anchor and the barrel; and a mechanical anchor
engaged with the second tubular connector.
2. A rock anchor assembly according to claim 1 wherein the flexible element is a length
of cable manufactured from steel or a composite material.
3. A rock anchor assembly according to claim 1 or 2 wherein the connector elements are
made of a steel or a composite material.
4. A rock anchor assembly according to claim 3 wherein the connector element is made
of a steel material and the connector element is swaged onto the respective proximal
and distal end portions of the cable.
5. A rock anchor assembly according to any one of claims 1 to 4 wherein the load bearing
barrel is comprised of a solid body of a metal material which has a domed or conical
forward end and an opposed back end.
6. A rock anchor assembly according to claim 5 wherein the barrel has a plurality of
grout conduits.
7. A rock anchor assembly according to any one of claims 1 to 6 wherein the tensioning
means is a nut which is threaded onto complementary threads formed on the first tubular
connector.
8. A rock anchor assembly according to any one of claims 5 to 7 wherein the assembly
includes a tubular spacer on the rock anchor between the first end of the sleeve and
the forward end of the barrel or between the back end of the barrel and the tensioning
means.
9. A rock anchor assembly according to claim 8 wherein the tubular spacer is made of
a suitable plastics material which deforms or breaks when a compressive force is applied
to it to collapse or break away from the rock anchor, allowing the rock anchor to
move longitudinally relatively to the sleeve between a first position and a second
position.
10. A rock anchor assembly according to claim 9 wherein the sleeve has a flared end section
which opens onto the first end and an anchor housing section which opens onto the
second end.
11. A rock anchor assembly according to claim 10 wherein the mechanical anchor is at least
partially received within the anchor housing section of the sleeve in an unexpanded
configuration when the rock anchor is in the first position.
12. A rock anchor assembly according to claim 11 wherein the mechanical anchor moves from
the anchor housing section of the sleeve into an expanded configuration when the rock
anchor is in the second position.
13. A method of anchoring a rock anchor assembly within a rock hole, the rock anchor assembly
including a flexible outer sleeve which extends between a first end and a second end;
a rock anchor which locates, at least partially within the sleeve, such that end parts
of the rock anchor extend beyond the first end and the second end of the sleeve, the
rock anchor comprising a flexible cable and a first and a second cylindrical connector
element engaged to a proximal end portion and a distal end portion respectively, with
the first cylindrical connector element carrying a mechanical anchor which is at least
partly held within the sleeve in a closed position and the second cylindrical connector
element being at least partly threaded, a faceplate located over the sleeve, a barrel
on the threads of the second connector element and a fastener on the threads between
the barrel and a proximal end of the rock anchor, the method including the steps of
pre-spacing the barrel from the first inlet end or the fastener from the barrel, inserting
the rock anchor assembly into a predrilled rock hole, a distal end of the rock anchor
leading, until the faceplate is sandwiched between rock wall and the sleeve or the
barrel and pushing the anchor further into the rock hole to close the pre-spacing
allowing the rock anchor to move relatively to the sleeve to drive the mechanical
anchor from the first end of the sleeve and into a radially expansive open position
in which the mechanical anchor resistively engages the walls of the rock hole.
14. A method according to claim 13 wherein the pre-spacing of the barrel from the first
end of the sleeve or the pre-spacing of the fastener from the barrel is achieved by
interspasing a tubular spacer on the cable anchor, between the first end of the sleeve
and the barrel or between the barrel and the fastener.
15. A method according to claim 14 wherein the pre-spacing is closed by deforming or breaking
the tubular spacer.
16. A method according to any one of claims 13 to 15 which includes additional steps of
engaging a coupling device to the barrel and pumping a grout material from a source
through the coupling device and at least one channel provided in a sidewall of the
barrel, into an annular space between the sleeve and the cable anchor and into an
annular space between the sleeve and walls of the rock hole.