U.S. patent application number 13/262707 was filed with the patent office on 2012-07-12 for grout delivery system for a rock bolt.
This patent application is currently assigned to Aveng (Africa) Limited. Invention is credited to Michael Martin Charles Howell, Johann Steyn.
Application Number | 20120177448 13/262707 |
Document ID | / |
Family ID | 41345109 |
Filed Date | 2012-07-12 |
United States Patent
Application |
20120177448 |
Kind Code |
A1 |
Steyn; Johann ; et
al. |
July 12, 2012 |
GROUT DELIVERY SYSTEM FOR A ROCK BOLT
Abstract
A grout delivery device which includes a body which defines an
internal volume (18), opposing first (34) and second (26) apertures
in the body, in communication with the volume, through which a rock
support tendon (50) extends, and a grout formation (44) on the body
for connection to a grout source.
Inventors: |
Steyn; Johann; (Sasolburg,
ZA) ; Howell; Michael Martin Charles; (Rayton,
ZA) |
Assignee: |
Aveng (Africa) Limited
Germiston
ZA
|
Family ID: |
41345109 |
Appl. No.: |
13/262707 |
Filed: |
June 15, 2009 |
PCT Filed: |
June 15, 2009 |
PCT NO: |
PCT/ZA09/00053 |
371 Date: |
March 27, 2012 |
Current U.S.
Class: |
405/259.5 |
Current CPC
Class: |
E21D 20/028
20130101 |
Class at
Publication: |
405/259.5 |
International
Class: |
E21D 20/02 20060101
E21D020/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2009 |
ZA |
2009/02313 |
Claims
1. A grout delivery device for use with a bearing plate and a rock
support tendon which extends through an opening in the bearing
plate, the device including a body which defines an internal
volume, a first aperture positioned in a surface of the body which
opposes an inner surface of the bearing plate, a second aperture in
the body which opposes the first aperture, the rock support tendon
extending through the first and second apertures which are in
communication with the volume, and a grout opening in the body
which is displaced from the first and second apertures and through
which grout is injectable into the volume.
2. A device according to claim 1 wherein the body includes a first
body, portion in which the first aperture and the grout opening are
located and a second body portion in which the second aperture is
located.
3. A device according to claim 2 wherein the second body portion is
movable relative to the first body portion at least to a limited
extent.
4. A device according to claim 3 wherein the body includes
bellows-type formations which allow the second body portion to be
movable relative to the first body portion.
5. A device according to claim 2, wherein an outer surface of the
first body portion surrounds the first aperture and is convex,
semi-spherical or conical in shape.
6. A device according to claim 2 wherein the second body portion is
substantially tubular.
7. A device according to claim 1 wherein the grout opening is
formed by a spigot which projects from the body and through which
is formed a passage.
8. An assembly of a device according to claim 1 and a bearing plate
which includes an opening which is aligned with the first aperture
in the body and a second opening which is in register with the
grout opening in the body.
9. An assembly according to claim 8 which includes a rock support
tendon which extends through the first and second apertures and
through the opening of the bearing plate.
10. An assembly according to claim 9 which includes a seal at an
interface of the device and the rock support tendon in the region
of the first aperture.
11. An assembly according to claim 8 which includes an elongate
tube which is engaged with the body in direct communication with
the second aperture.
12. An assembly according to claim 8 wherein the bearing plate has
a domed area in which the opening is located.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates, generally, to the delivery of grout
to a rock support tendon and more particularly is concerned with a
device to assist in delivering grout to a drill hole in which a
rock support tendon is to be anchored.
[0002] As used herein "grout" includes a cementitious mixture and
any other settable mixture which can be employed to anchor a rock
support tendon in position, and "rock support tendon" includes,
without being limited, a rock bolt, a cable anchor and similar
support devices.
[0003] The grouting of rock support tendons is a widespread
practice. The grout protects the support tendons from any ground
water which may be present and which could cause the support
tendons to corrode and, secondly, the support performance of the
support tendons is enhanced for the grouting increases the
capability of the support tendons to resist shear forces in the
surrounding rock.
[0004] When a rock support tendon is grouted in a drill hole,
provision must be made for air which is trapped in the drill hole
to escape to atmosphere. One system in use employs a first tube for
delivering the grout to the drill hole and a second tube to allow
air to escape from the drill hole. Ends of the tubes protrude into
a working place at which the rock support tendon is installed and
are subject to blast damage--a factor which can make grouting
difficult or impossible.
[0005] In a second approach, of which the applicant is aware, use
is made of a hollow spherical device which is seated on an outer
side of a bearing plate or washer which is engaged with a
protruding end of the rock support tendon. Grout is delivered to
the drill hole through the hollow interior of the device. The
spherical device is however also exposed to the workplace and can
therefore be damaged by blasting or by moving machinery.
[0006] An object of the present invention is to provide a device
which facilitates delivery of a grout to a drill hole and which, to
a substantial extent, is protected against damage of the
aforementioned kind.
SUMMARY OF INVENTION
[0007] The invention provides a grout delivery device which
includes a body which defines an internal volume, opposing first
and second apertures in the body, in communication with the volume,
through which a rock support tendon extends, and a grout formation
on the body for connection to a grout source.
[0008] Preferably the body is at least partly flexible
[0009] The body may have a first body portion in which the first
aperture is located and a second body portion in which the second
aperture is located. The second body portion may be movable
relative to the first body portion at least to a limited
extent.
[0010] The internal volume may be in the nature of a passage or
chamber or a similar space which is at least partly enclosed.
[0011] The flexibility of the body may be achieved in any
appropriate way. For example different portions of the body may be
made from different materials. Another possibility is for the body
to be made with one or more lines of weakness which facilitate
flexing of the body. A third possibility is for the body to be
formed with formations in the nature of a bellows or the like.
These types of construction are exemplary only and are
non-limiting.
[0012] The formation, for connection to the grout source, is
preferably located on the first body portion.
[0013] The first body portion is preferably bulbous.
[0014] An outer surface of the first body portion, surrounding the
first aperture, is preferably convex or semi-spherical, conical or
the like. Thus a cross-sectional dimension of the first body
portion measured between opposing points on the outer surface in a
direction which is transverse to an axis of the first aperture, may
increase in a direction away from a mouth of the first
aperture.
[0015] The second body portion may be substantially tubular. A
section of the body between the first body portion and the second
body portion may be slightly flared i.e. of decreasing
cross-section from the bulbous first body portion to the tubular
second body portion.
[0016] The formation for connection to the grout source may be in
the nature of a spigot and may include a formation which
facilitates engagement of the spigot with an opening, in a member
such as a bearing plate, through which the spigot is passed.
[0017] The invention also extends to an assembly of a device of the
aforementioned kind and a bearing plate which includes a central
opening which is aligned with the first aperture of the device and
a second opening through which the grout formation of the device
passes and, preferably, with which the grout formation is
engaged.
[0018] A rock support tendon may extend through the first and
second apertures and through the central opening of the bearing
plate. A seal may be provided at an interface of the device and the
rock support tendon in the region of the first aperture. The seal
may be of any appropriate kind and, by way of example only, may be
constituted by a washer of a flexible material such as rubber which
closely surrounds the rock support tendon and which engages with an
annular gap between the first body portion and the tendon.
Alternative the body can be formed with a small collar, which
protrudes into the volume, and which closely surrounds an adjacent
surface of the tendon.
[0019] The bearing plate could have any suitable shape and, for
example, is domed or flat or semi-conical.
[0020] The device may be used in different ways. In one form of the
invention an elongate tube is engaged with the body in direct
communication with the second aperture.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The invention is further described by way of examples with
reference to the accompanying drawings in which:
[0022] FIG. 1 is a side view of a device according to the
invention;
[0023] FIG. 2 shows the device in perspective;
[0024] FIG. 3 is a cross-sectional view, from one side, of the
device shown in FIG. 1;
[0025] FIG. 4 shows, in cross-section, the device engaged with a
rock support tendon, in one mode of use;
[0026] FIG. 5 shows the device used with a rock support tendon in a
different mode of use,
[0027] FIG. 6 shows the device when used with a cable anchor;
and
[0028] FIGS. 7 and 8 are perspective and cross-sectional views
respectively of a device according to a different form of the
invention.
DESCRIPTION OF PREFERRED EMBODIMENT
[0029] FIGS. 1, 2 and 3 of the accompanying drawings are side,
perspective and cross-sectional views respectively of a device 10
used for delivering grout to a rock support tendon, according to
the invention.
[0030] The device includes a body 12 formed by a first body portion
14 and a second body portion 16.
[0031] The body encloses an internal volume 18, in the nature of a
chamber.
[0032] The first body portion 14 is bulbous and has a convex or
semi-spherical outer surface 20. A first aperture 22 is centrally
positioned in the convex surface.
[0033] The second body portion 16 is formed by a short tube 24
which terminates in a second aperture 26 which directly opposes the
first aperture. An intermediate section 28 between the body
portions is flared and reduces in cross-section from the bulbous
first body portion to the tubular second body portion.
[0034] As is evident particularly from FIG. 3 the first body
portion 14 has a region 30 which is formed with ribs which impart
to the region a bellows-type appearance. As a consequence the
region 30 is flexible, at least to a limited extent, and the first
body portion can thus be moved relative to the second body portion
to some extent.
[0035] It is desirable for the body to be flexible, at least to a
limited extent, for reasons which are described hereinafter. This
flexibility can be achieved using any suitable technique and the
scope of the invention is not limited to the use of the
bellows-like strucutre. For example the body could be made from one
or more parts and the region 30 or the flared section 28 could be
made from a softer and more flexible material than remaining
portions of the body. Other approaches to achieve this desired
property of flexibility are of course possible e.g. by forming
appropriate sections of the body with lines of weakness which
promote bending or flexing of the body.
[0036] In this example of the invention (refer to FIG. 3) an
inwardly extending collar 34 is positioned at a rim of the first
aperture and extends into the volume 18.
[0037] A small spigot 38 is positioned on the outer surface 20. The
spigot is to one side of the first aperture and has a
frusto-conical leading end 40 followed by a small shoulder 42. A
passage 44 extends through the spigot.
[0038] FIG. 4 illustrates, in cross-section and from one side, one
way of using the device 10. A rock support tendon 46 has an
elongate rigid shank 50 which extends through the opposing first
and second apertures 22 and 26. A bearing plate 52 is passed onto
the shank over the convex outer surface 20 of the bulbous first
portion. The bearing plate has a domed central area 54 which is
sized to fit closely over the convex surface 20. The shank extends
through a centrally positioned opening 56 in the bearing plate. A
shaped washer 58, as is known in the art, is placed over the shank
and this is followed by a nut 60 which is threadedly engaged with a
protruding end 62 of the shank.
[0039] The bearing plate is formed with a small opening 64 and the
spigot 38 of the device is passed through this opening. The
shoulder 42 abuts and engages with a portion of the outer surface
of the bearing plate which surrounds the opening.
[0040] The shank extends through the tubular second portion 24 into
a drill hole 70 formed in a body of rock 74. An outer edge 76 of
the bearing plate abuts a surface of a rock face 78 surrounding the
drill hole 70.
[0041] The device 10 can be used in two ways, at least, depending
on the nature of the rock support tendon with which the device is
engaged. In one mode of use a tube 80 is engaged with a leading end
of the tubular second portion so that the second aperture 26 is in
direct communication with an interior of the tube. The tube can be
clamped or otherwise fixed to the tubular second portion. The tube
extends into the hole 70 to a required extent. Grout from a grout
delivery system, not shown, can then be injected into the passage
44 in the interior of the spigot. The grout flows into the volume
18 and then passes into an elongate annular volume 82 which
surrounds the shank and which is bounded by the inner surface of
the tube. As the grout advances air is expelled from the drill
hole, travelling on an outer side of the tube. The air eventually
reaches atmosphere through paths which are formed on an outer side
of the device 10.
[0042] In a second mode of use, illustrated in FIG. 5, the shank,
designated 50A, is formed with an elongate, axially extending, air
passage 84. In this mode of use the tube 80 is not used. When grout
is injected into the volume 18 it emerges from the second aperture
26 and fills an annular gap 86 between an outer surface of the
shank 50A and an opposing inner surface of the drill hole. Air
trapped inside the drill hole can escape, as the grout advances, by
entering a mouth of the passage 84 which is located at a far end of
the shank. When grout starts leaving the passage 84 it is evident
to an operator that the drill hole has been completely grouted.
[0043] In FIGS. 4 and 5 the rock face 78 is generally perpendicular
to the longitudinal direction of the drill hole. This is not
necessarily the case. In many applications, particularly in arduous
underground conditions, the rock face is inclined to the axial
direction of the hole. Clearly, the orientation of the rock support
tendon is determined by the hole direction. Similarly, the
orientation of the bearing plate is determined by the orientation
of the rock face surrounding the mouth of the drill hole. It is for
this reason that a degree of flexibility of the body of the device
is required. The tubular second portion is inserted into the drill
hole and is therefore not able to be moved to any meaningful
extent. The bulbous first portion which is captured by the domed
bearing plate must be movable, together with the bearing plate,
relatively to the rock support tendon. The bellows-like region 30
allows this movement to take place.
[0044] FIG. 6 shows the use of the device with a tendon 46A which
includes an elongate, slightly flexible, cable 50B, and not a rigid
shank.
[0045] An end 90 of the cable projects from a mouth of a drill hole
70 formed in a rock body 74, and passes through a volume 18 inside
a device 10A which is similar to the device 10, but which includes
an additional tubular spigot 98. Other parts of the device 10A,
which are the same as parts of the device 10, bear similar
reference numbers. The device 10A is located inside a bearing plate
52 in that it has an opening 100 through which the spigot 98
extends.
[0046] A breather tube 102 extends through the spigot 98, and the
volume 18, into the drill hole 70 and, alongside the cable 50B, to
an inner end of the drill hole.
[0047] A barrel 106 is passed onto the end 90 and a wedge 108 is
engaged with the end 90 and the barrel, which bears against an
outer face of the bearing plate 52. These components are used to
tension the cable, as is known in the art. Grout is injected into
the drill hole through the spigot 44 and fills the annular space
between the cable and a wall of the drill hole. Air is expelled
through the breather tube 102.
[0048] FIGS. 7 and 8 show another device 10B according to the
invention in perspective and in cross-section respectively. The
device has a body 12B with a first, frusto-conical, portion 14B and
a second, tubular, portion 16B. The portion 14B has a plurality of
apertures 112, and two formations 98B and 44B which correspond to,
and which perform the same functions as, the spigots 98 and 44
respectively. The apertures 112 weaken the body and allow for a
degree of relative movement between the body portions 14B and 16B.
A passage 18B, through the body 12B, acts in the same way as the
volume 18.
[0049] The device 10B is used in the same way as the device 10A,
but preferably with a bearing plate of a corresponding shape i.e.
not as domed as the bearing plate 52.
* * * * *