WO2010006374A1

WO2010006374A1 - Stabilising rock masses

Info

Publication number: WO2010006374A1
Application number: PCT/AU2009/000912
Authority: WO
Inventors: Murray Robert Clair
Original assignee: Nupress Tools Pty Limited
Priority date: 2008-07-18
Filing date: 2009-07-17
Publication date: 2010-01-21
Also published as: AU2009270337A1

Abstract

A rod for fixing in a rock mass or strata, including an elongate body with a deformable section adapted to deform to a deployed condition under load, to engage a wall of a bore in which the rod is positioned, to anchor the rod in place.

Description

STABILISING ROCK MASSES

Related Applications

This application claims priority from United States Patent Application No. 61/129,782, filed 18 July 2008, the contents of which are incorporated herein by reference.

Field of the Invention

The present invention relates generally to the stabilising of rock masses or strata such as for example in mines.

Background to the Invention

In underground mines it is important for many reasons that the mine walls and/or roof is effectively stabilised. This often involves providing support and reinforcement of the mine walls. For example during mine excavations reinforcement of the mine walls may be effected using devices such as cable bolts, rock bolts and the like. It is important to note that to use existing products a bore must first be produced by a drill and the drill is then retracted after which the rock bolt or cable bolt is inserted and then anchored either mechanically or chemically with resin.

Summary of the Invention

In accordance with the present invention, there is provided a rod for fixing in a rock mass or strata, including an elongate body with a deformable section adapted to deform to a deployed condition under load, to engage a wall of a bore in which the rod is positioned, to anchor the rod in place.

In another aspect, there is provided a drill bit for use with the above described rod including a wedge piece provided with a shaft for receipt in a coupling section of the rod. In yet another aspect, there is provided a drill rod including a combination of the drill bit and rod.

In another aspect, there is provided a method of fixing a drill rod, as described above, in a rock mass or strata, including applying rotational drive to the rod to drill a bore and applying an axial load to plastically deform the deformable section against a wall of the bore, to anchor the rod in place.

According to another aspect of the present invention there is provided a reinforcing rod which is suitable for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions, coupling sections at each of the end portions and a through hole extending through the rod body between the end portions.

According to another aspect of the present invention there is provided a rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and helically arranged formations on the outer surface of the rod body which extend at least partially along the length thereof between the opposed end portions, the helical formations being uni-directional. The helical direction may be left or right hand.

The helical formations may be in the form of a plurality of ribs disposed in spaced relation to one another along the length of the main body. In one form two groups of ribs are provided which are on opposite sides of the rod body and configured so as to together provide a discontinuous helical profile. Although a full continuous uninterrupted helix may be used.

According to another aspect of the present invention there is provided a rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and helically arranged formations on the outer surface of the rod body which extend at least partially along the length thereof between the opposed end portions, the helical formations being uni-directional. The helical direction may be left or right hand. This rod serves a dual purpose firstly being the drill body transmitting torsion forces from the drill rig to the drill bit as well as providing a through hole for flushing water through the centre passage of the rod. Secondly the helical ribs protruding from the cylindrical surface of the rod provide an extraction mechanism for the drilled strata as well as anchoring lugs for the resin anchor.

Reinforcing rods of this type may be adapted for use in a reinforcing system which forms another aspect of the invention and which comprises two or more of the rods with one or more coupling members arranged to secure two adjacent rods together in end to end relation. Each coupling member may include connector sections to which the adjacent ends of adjacent rods can be secured. The coupling member may include a central through passage extending between the connector sections, the through passageway being in fluid communication with the through holes in the rods and one or more lateral passageways extending from the through passage to the outer surface of the coupling member. In one form a singular or plurality of passageways are provided which extend generally in a radial direction with respect to the coupling member body.

According to yet another aspect of the present invention there is provided a method of reinforcing a rock mass or strata using reinforcing rods of the type described above, the method including the steps of attaching a drill bit to one end of one of the rods, forming a drill hole using the drill bit so as to penetrate the rock mass or strata so that the drill hole accommodates two or more of the rods in end to end relation with adjacent rods being connected by the coupling members described above and thereafter introducing grouting so that it flows along the through holes and passages in the coupling member so that the grout fills the space between the drill hole wall and the rods and at least some of any cracks in the rock mass or strata.

The lateral passageway in the coupling member or members may contain a mechanical valve or be filled with resin which can blow out when the pressure of the grouting in the through hole reaches a sufficient pressure.

According to yet another aspect of the present invention there is provided a reinforcement rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and coupling sections and each end portion, one of the coupling sections being adapted to have mounted thereto a drill bit, the arrangement being such that when the drill bit has completed forming a drilled hole and the drill bit is adjacent the blind end of the drilled hole displacement of the rod body towards the blind end causes the drill mounted end of the rod to expand as a result of the relative movement between the rod and drill bit thereby providing an anchorage.

Brief Description of the Drawings

In order to enable a clear understanding of the invention drawings exampling embodiments of the invention will hereinafter be described with reference to the accompanying drawings, and in those drawings:

Figure l is a perspective view of a rod;

Figure 2 is a side view of a rod, showing coupling sections;

Figure 3 is a perspective view of the rod of Figure 2, fitted with a drill bit;

Figure 4 is a schematic side elevation of an assembly of rods of the type illustrated in Figure 1 in an installed position;

Figure 5 is a cross-sectional view of a coupling member;

Figure 6 is a sectional view taken along the line AA, shown in Figure 5;

Figures 7 to 9 are cross-sectional views illustrating operation and anchoring of the rod;

Figure 10 is a perspective view of an end portion of the rod; and

Figure 11 shows cross-sectional and end views of the end portion. Description of a Preferred Embodiment

Referring to Figure 1 there is illustrated a reinforcing rod 1 for use in the reinforcement of a rock mass or strata. The rod 1 comprises an elongated rod body 2 having opposed end portions 3 and 4 with a longitudinal axis extending therebetween. The reinforcing rod 1 further includes a through hole 5 in the rod body 2 which extends between the opposed end portions 3 and 4 thereof. The rod body 2 has on its outer surface a series of formations 6 in the form of ribs 7 which are arranged in spaced apart relation along the length of the rod body 2. There are two groups of ribs 7 provided on either side of the outer surface of the rod body 2. The two groups of ribs are arranged so as to provide a discontinuous helical formation around the outer surface 8 of the rod body 2, the helical formation extending from one end portion 3 thereof to the other end portion 4. The ribs 7 provide for a right hand helix which can aid in mud extraction and assist in grip for grounding. The through hole 5 can serve the purpose of water flushing during the drilling cycle and for the insertion of grouting. The grouting is used to bond the rod body 2 to the rock mass or strata so that in effect it forms an integral part of the rock mass or strata.

Figure 4 illustrates a typical reinforcing arrangement utilising a series of reinforcing rods 10, 11, 12 and 13 of a type described earlier. A drilling machine 15 enables location of the reinforcing rods which are interconnected by coupling members 16 of a type shown in Figures 5 and 6. A coupling member 16 comprise a body 17 having connector section 18 and 19 at each end thereof with a through passageway 20 and laterally extending passageways 21, 22, 23 and 24 extending from the through passageway 20 to the outer surface of the connector body 17. Grouting can flow along the through holes 5 in the rods 10 to 13 as well as the through passageway 20 in the coupling members 16 and out through the lateral passageways 21 to 24.

Figures 2 to 3 illustrate further features of a reinforcing rod 1 according to another embodiment, where like parts are denoted by like reference numerals. In this embodiment the rod body 2 has coupling sections 30 and 31 at each end portion 34 thereof. One of the coupling sections 31 comprises an external threaded part 32. At the other end portion 3 slots 33 are provided which enable that end portion 3 to expand under linear force being applied thereto. This end portion 3 is adapted for use with a drill bit 34 which has a locking flange 35 associated therewith and can engage an internal threaded section 36 of the end portion 3 of the rod body 2. Once drilling has been completed further movement of the rod body 2 in the longitudinal direction causes deformation of the end portion 3 to provide an anchorage in the rock mass or strata. The through hole 5 can be used for supplying grouting around the rod body 2 as described earlier.

Turning now to Figure 7, a more detailed view of an end portion 3 of a rod 1 is shown. The end portion 3 includes both a coupling section 40 and a deformable section 41. The deformable section 41 has a reduced wall thickness, as compared to the remainder of the rod body 2 and is in effect integral with the coupling section 40 since the coupling section 40 is part of and is recessed into the deformable section 41.

The deformable section 41 defines an opening 42 which has a bevelled surface 43 that leads into an internal thread 44 of the coupling section 40. A wedge piece 50, which is integrally formed with the drill bit 34, is securely mounted in the coupling section 40 by way of a shaft 51 of the wedge piece 50 being received through the opening 42 and thread 52 on the shaft 51 engaging with the internal thread 44 of the coupling section 40.

A locking projection 53 is provided on the wedge piece 50 in the form of the annular flange 35. In the condition shown, the drill bit 34 has been screwed into the coupling section 40 until the flange 35 is in abutment with the end 54 of the rod. In that position, the rod is arranged for a drilling operation and flushing air or water can be pumped up through hole 5 during drilling, as indicated by arrow A.

In order to activate the deformable section 41, a compressive load is applied to force the end portion 3 of the rod 1 against the drill bit 34, as indicated by arrows 'B'. This causes the deformable section 41 to flare outwardly and plastically deform over the wedge piece 50, as illustrated in Figure 8. More particularly, the bevelled surface 43 is caused to ride up over the flange 35, which causes the deformable section 41 to splay and drives the wedge piece 50 further into the coupling section 40. As the coupling section 40 moves over the flange 35, the successive ridges of the thread 44 lock onto the flange 35 to prevent reverse movement of the rod 1. Further axial loading of the rod 1, as indicated by arrow 'C in Figure 9, causes the deformable section 41 to fully plastically deform against a wall 55 of a bore 56 formed by the drill bit 34, which thereby serves to mechanically anchor the rod 1 in the bore 56. In that position, settable material, such as a resin anchor material, may be injected up the through hole 5, which extends the length of the rod 1, and through the drill bit 34 as well, to fix the rod 1 in the bore 56.

Figure 10 shows a perspective view of the end portion 3 of the rod 1. The deformable section 41 is more clearly shown as being formed of separate parts 60 which are separated by elongate, axially extending grooves 61, to facilitate easier deformation of the end portion 3 of the rod 1.

Figure 11 shows cross-sectional and end views of one particular example of an end portion 3 where specific dimensions are provided for the benefit of illustrating one particular rod example.

However, different dimensions may, of course, be used as required in order to achieve the same result with different gauge rods for different loading requirements.

For example, the rod can be scaled up or down to meet the relevant holding requirements of the mine. Some commercial bolts for instance that are supplied by DSI can be supplied with 16t, 2Ot or 25t holding force. This is achieved by using different diameter re-bar and also different tensile strength material to make the re-bar from. The chemical composition of the re-bar material can also be altered to make it a higher tensile strength or the next size in diameter can be used and a larger drill bit fitted into the rod.

The drill bits are preferably made from AS 1440/4140 or 4340.

The rod is of a similar tensile strength.

During drilling of test material approximately 100Kn of thrust force was applied. After drilling with the system in a non rotating state an axial thrust force of 300Kn was used to set and lock the wedge bit in position. After the system had been locked, it was found that in the sandstone sample drilling block the bold could not be removed with a 2OT hollow hydraulic enerpac system. Therefore, in ideal sandstone conditions the system could be used without the post grouting or resin injection.

It should also be appreciated the coupling of the rod 1 with the drill bit 34 need not necessarily be a screw type coupling, as described, and many other possible means of engagement may be employed, such as bayonet type coupling or the like.

Regardless of the particular dimensional requirements or coupling mechanisms employed, the use of a single rod 1 with a drill bit 34 and a simple mechanically activated deformable anchor provides a number of advantages. There are less component parts compared to prior art anchoring mechanisms, the self drilling capability reduces installation time. The through hole allows for both wet and dry drilling and subsequent grouting, if required, while the ribs allow for mud and dirt extraction during drilling. Additionally, due to the compact nature of the rod and drill bit, factory floor space and manufacturing costs can be minimised. The ability to have coupling portions formed at either end of the rod also provides for universality in so far as the rod can also be coupled to other rods to form a cable bolt or drill string, if needed.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

Finally, it is to be understood that the inventive concept in any of its aspects can be incorporated in many different constructions so that the generality of the preceding description is not to be superseded by the particularity of the attached drawings. Various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention. CLAIMS:

1. A rod for fixing in a rock mass or strata, including an elongate body with a deformable section adapted to deform to a deployed condition under load, to engage a wall of a bore in which the rod is positioned, to anchor the rod in place.

2. The rod of claim 1, wherein the rod has a coupling section at an end portion thereof for connecting to a wedge piece.

3. The rod of claim 2, wherein the deformable section is arranged to deform against the wedge piece when the load is applied though the rod.

4. The rod of claim 2, wherein the coupling section has a throat for receiving and securing a shaft of the wedge piece, which carries a drill bit, so that the rod is adapted for self-drilling.

5. The rod of claim 4, wherein the throat has an inner profile arranged to ratchet onto a locking projection formed on the wedge piece when the load is applied to the rod.

6. The rod of claim 5, wherein the inner profile is a thread formed on an inside surface of the coupling section.

7. The rod of claim 6, wherein the deformable section is provided at an end of the rod and is recessed to define the coupling section.

8. The rod of claim 7, wherein an opening defined by the deformable section is bevelled to provide a surface adapted to ride over the wedge piece as the wedge piece is forced into the coupling section, when the deformable section deforms under the load.

9. The rod of claim 8, wherein the deformable section is formed of a plurality of parts separated by axially extending grooves and wherein the parts plastically deform under the load, to engage the bore wall.

10. The rod of any one of claims 2 to 9, wherein the coupling section is adapted to couple to either a drill bit or a corresponding end of another rod.

11. The rod of any one of claims 1 to 10, including a through hole extending the length of the rod.

12. A drill bit for use with the rod of claim 1, including a wedge piece provided with a shaft for receipt in a coupling section of the rod.

13. The drill bit of claim 12, wherein the wedge piece includes a locking projection to abut an end of the rod and subsequently be engaged by the coupling section when deformed over the wedge piece.

14. The drill bit of claim 13, wherein the locking projection is in the form of an annular flange.

15. The drill bit of claim 13, wherein the shaft is threaded to engage with a corresponding thread of the coupling section.

16. The drill bit of claim 12, including a through hole arranged to be aligned with a through hole in the rod when fixed thereto.

17. A drill rod, as defined in any one of claims 1 to 11, in combination with a drill bit, as defined in any one of claims 12 to 16.

18. A method of fixing a drill rod, as defined in claim 17, in a rock mass or strata, including applying rotational drive to the rod to drill a bore and applying an axial load to plastically deform the deformable section against a wall of the bore, to anchor the rod in place.

19. The method of claim 18, including injecting settable material up a through hole provided in the rod, for exit from the remote end of the rod to secure the rod in the bore.

20. The method of claim 18, wherein a plurality of rods are connected together for drilling prior to application of the axial load.

21. A reinforcing rod which is suitable for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions, coupling sections at each of the end portions and a through hole extending through the rod body between the end portions.

22. A reinforcing rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and helically arranged formations on the outer surface of the rod body which extend at least partially along the length thereof between the opposed end portions, the helical formations being uni- directional.

23. A reinforcing rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and helically arranged formations on the outer surface of the rod body which extend at least partially along the length thereof between the opposed end portions, the helical formations being unidirectional. The rod being arranged so that firstly it is the drill body transmitting torsion forces from the drill rig to the drill bit as well as providing a through hole for flushing water through the centre passage of the rod, and secondly the helical formations protruding from the cylindrical surface of the rod provide an extraction mechanism for the drilled strata as well as anchoring lugs for the resin anchor.

24. A method of reinforcing a rock mass or strata using reinforcing rods of the type described above, the method including the steps of attaching a drill bit to one end of one of the rods, forming a drill hole using the drill bit so as to penetrate the rock mass or strata so that the drill hole accommodates two or more of the rods in end to end relation with adjacent rods being connected by the coupling members described above and thereafter introducing grouting so that it flows along the through holes and passages in the coupling member so that the grout fills the space between the drill hole wall and the rods and at least some of any cracks in the rock mass or strata.

25. A reinforcement rod for use in the reinforcement of a rock mass or strata, the rod comprising an elongated rod body having opposed end portions and coupling sections and each end portion, one of the coupling sections being adapted to have mounted thereto a drill bit, the arrangement being such that when the drill bit has completed forming a drilled hole and the drill bit is adjacent the blind end of the drilled hole displacement of the rod body towards the blind end causes the drill mounted end of the rod to expand as a result of the relative movement between the rod and drill bit thereby providing an anchorage.

26. A rod, substantially as described with reference to the drawings and/or Examples.

27. A method of drilling, substantially as describer with reference to the drawings.