AU2018200916A1 - A Blast Hole Stabiliser - Google Patents

Abstract

Abstract A blast hole stabiliser comprises an inflatable bladder for insertion into a blast hole when the bladder is uninflated. The bladder is arranged so that it can be inserted into an appropriately sized blast hole and then inflated. During inflation the bladder expands in length further into and lines the blast hole.

Description

Field of the Invention [001] The present invention relates to an inflatable blast hole stabiliser and a method of stabilising blast holes using an inflatable blast hole stabiliser.

Background [002] Sub-surface mining frequently requires the use of explosives to break down a geological structure above and surrounding a tunnel into a desired rubble form. A common technique to achieve this involves the drilling of holes to a required depth and loading the holes with explosive which can be detonated resulting in the creation of rubble which can be mined form within the tunnel.

[003] Typically one section of the tunnel is blasted at a time. Commonly, the part of the tunnel further down the section to be blasted is drilled, but not loaded with explosives. If the geological structure is unstable or becomes unstable due to the adjacent blast, the drilled holes can sometimes collapse or become discontinuous, which restricts the ability to load them with explosive, thereby causing inconvenience.

[004] A common method of alleviating this problem is to stuff a slotted PVC pipe or inflatable tube into the drilled hole and then once the tube is in position, the tube is inflated so as to stabilise the hole. Typically these tubes are stuffed into the hole by various ah-hoc means including using a hose to push the tube up the hole. This is ineffective and time consuming.

[005] It is an object of the invention to provide an improved inflatable blast hole stabiliser.

[006] In this specification, the terms “comprising”, “comprise”, or similar, are used inclusively and not exclusively or exhaustively.

[007] Any references to documents that are mad in this specification are not intend to be an admission that the information contained in those documents form part of the common general knowledge known to a person skilled in the field of the invention, unless explicitly stated as such.

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Summary of the Present Invention [008] According to an aspect of the invention there is provided a blast hole stabiliser comprising an inflatable bladder for insertion into a blast hole when the bladder is uninflated, wherein the bladder is arranged so that it can be inserted into an appropriately sized blast hole and then inflated, whereby during inflation the bladder extends in length further into and lines the blast hole.

[009] In an embodiment, the bladder is cylindrical in shape.

[0010] in an embodiment, the bladder is a tube.

[0011] In an embodiment, the bladder is made from airtight and flexible extruded plastic.

[0012] In an embodiment, the majority of the extended length of the bladder is inside of the unextended length of the bladder before it is inflated.

[0013] In an embodiment, a portion of the bladder is configured to be out-side-in prior to being inflated so that as the bladder is inflated and extends in length it turns in-side-out.

[0014] In an embodiment the bladder is gathered inside itself.

[0015] In an embodiment, the bladder is folded inside itself.

[0016] In an embodiment, the blast hole stabiliser further comprises a protective sheath housing the bladder in its uninflated state. In an embodiment the protective sheath is configured such that when the protective sheath is inserted into the opening of a blast hole, the uninflated bladder it also inserted into the blast hole and can then be inflated so as to extend in length further into the blast hole from within the sheath.

[0017] In an embodiment, the protective sheath is made from semi-rigid woven laminated plastic.

[0018] In an embodiment, the protective sheath is about 1500 mm long.

[0019] In an embodiment, the blast hole stabiliser further comprises a valve for allowing one-way passage of a fluid to inflate the bladder.

[0020] In an embodiment, the valve penetrates a hole in the protective sheath.

2018200916 07 Feb 2018 [0021] In an embodiment, the bladder inflates into the blast hole lengthwise firstly and then pressurises diametrically against the wall of the blast hole.

[0022] In an embodiment, the bladder inflates to a diameter between about 64mm and 115mm.

[0023] In an embodiment, the bladder is about 10 meters, 15 meters, 20 meters, 25 meters or 30 meters or greater in length when fully extended.

[0024] In an embodiment, the bladder is inflated to between about 5psi and about 10 psi or 10psi and 50psi.

[0025] According to a further aspect of the invention, there is a method for stabilising a blast hole using a blast hole stabiliser, said method comprising providing an inflatable bladder tube which is extendable in length when inflated; inserting the bladder into a blast hole and inflating the bladder so that it extends in length further into the blast hole and lines a wall of the blast hole.

Description of Drawings [0026] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0027] Figure 1 is a perspective view of a blast hole stabiliser according to an embodiment of the present invention in a deflated state;

[0028] Figure 2 is side elevation of the blast hole stabiliser of Figure 1;

[0029] Figure 3 is a schematic plan view of the blast hole stabiliser of Figure 1 inserted into a bored hole and in an inflated state;

[0030] Figure 4 is a schematic view of a first embodiment of a blast hole stabiliser in a deflated state, inserted in to a bored hole [0031] Figure 5 is a schematic view of the blast hole stabiliser of Figure 4 at the commencement of inflation;

[0032] Figure 6 is a schematic view of the blast hole stabiliser of Figure 4 in a first partly inflated state;

[0033] Figure 7 is a schematic view of the blast hole stabiliser of Figure 4 in a second partly inflated state;

[0034] Figure 8 is a schematic view of the blast hole stabiliser of Figure 4 in a third partly inflated state;

2018200916 07 Feb 2018 [0035] Figure 9 is a schematic view of the blast hole stabiliser of Figure 4 in a fourth partly inflated state;

[0036] Figure 10 is a schematic view of the blast hole stabiliser of Figure 4 in an inflated state;

[0037] Figure 11 is a schematic view of a second embodiment of a blast hole stabiliser in a deflated state; and [0038] Figure 12 is a schematic view of a third embodiment of a blast hole stabiliser in a deflated state.

Detailed Description of Embodiments of the Invention [0039] Referring to Figure 1 there is shown a blast hole stabiliser 10 comprising an inflatable bladder 30 (seen in Figures 4 to 12), an associated sheath 12, and a valve 16 incorporated into the inflatable bladder 30 and sheath 12. The sheath 12 has an open end 18 and a closed end 20. The sheath 12 is preferably made from semi-rigid woven laminated plastic and in one embodiment is about 200 - 1500 mm long.

[0040] The closed end 20 comprises a further protective pocket 14 surrounding the end potion of the sheath 12. The sheath 12 may comprise gussets 15 on either side to allow expansion transverse to its length. The sheath 12 may be optional, but is desirable because it protects the bladder 30 during insertion into the opening 24 of a borehole 28 into a geological structure 26, also known as a blast hole, when it is filled with explosive. The protective pocket 14 provides further protection to the interface of the bladder 30 to the valve 16. The protective sheath also provides resilience from inflation since the internal bladder 30 can be semi resilient (elastic) whereas the sheath is resilient withstanding a higher pressure before elongation/loss of shape.

[0041] The valve 16 is able to be connected, such as by use of a snap-on fitting to a pressurised fluid (such as pressurised air) supply via hose and fitting 22.

[0042] Inside the sheath 12 is the inflatable bladder 30, which is initially in an uninflated state. As seen in Figure 4 the sheath 12 is inserted into the borehole 28, which enough of the sheath 12 protruding from the opening 24 so that the hose and fitting 22 can be attached to the valve 16. When the sheath is inserted into the borehole 28, so is the bladder 30 because it is inside of the sheath 12. The bladder 30 is arranged so that it can be inflated, whereby during inflation the bladder 30 extends in length further into and lines the blast hole 28 as shown in the progression of figures from Figure 4 to Figure 10.

2018200916 07 Feb 2018 [0043] In Figure 10, the bladder 30 is shown in a fully inflated state, such that it would line an appropriately sized borehole 28.

[0044] In an embodiment, the bladder 30 can be 10 meters, 15 meters, 20 meters, 25 meters or 30 meters in length and can line a borehole approximately equal to or lesser then that length of the bladder 30. In Figure 9 the borehole will be slightly less than the length of the bladder, whereas in Figure 10 the bladder 30 is substantially the same as the length of the borehole. The present invention can be used for boreholes longer than the length of the bladder 30, but this is less desirable as the remaining length of the borehole beyond the length of the bladder 30 will not be stabilised.

[0045] In the event that the hole is shorter than the length of the bladder 30, the end of the blast hole 28 will prevent further internal bladder from unravelling, whereby the surplus will remain on the inside of the bladder 30.

[0046] In an embodiment of the invention, a 20 meter bladder can line a blast hole (not shown) approximately equal to or lesser then that length of the bladder. Once the bladder has expanded along the length of a blast hole, it can then expand diametrically to line a blast hole between 64mm and 115mm.

[0047] The bladder 30 is a cylindrical tube made from air tight and flexible extruded plastic that is high strength, semi-elastic, and puncture resistant.

[0048] The bladder 30 is arranged to have its full length compressed, folded, festooned, rolled, compacted or otherwise inside of the length of the sheath 12, prior to inflation. Preferably, prior to inflation, the full length of the bladder 30 is compressed to be short of the open end 18 of the sheath 12, so that an end portion of the sheath at the open end 18 can be folded over to ensure the bladder 30 stays within the sheath 12 until an operator is ready to deploy the stabiliser 10.

[0049] In an embodiment, a portion of the bladder 30 is configured to be out-side-in prior to being inflated so that the bladder is compressed in length. The bladder 30 has a first portion which extends a significant portion of the length of the sheath 12 that is outsideout and a remaining portion that is outside-in, inside the first portion. The turned in on itself interface is 34. Further, as the bladder 30 is inflated it extends in length by turning the remaining portion in-side-out. In an embodiment the bladder is gathered inside itself

2018200916 07 Feb 2018 as depicted in Figure 4. In an alternative embodiment the bladder 30 is folded inside itself as schematically depicted in Figure 11 or 12.

[0050] It can be seen in Figure 4 that the remaining portion 32 of the bladder inside of the first portion of the bladder 30 is gathered so as to be in a compressed or compacted form. Figures 11 and 12 show forms where the remaining portion is folded, length-wise in the case of portion 40 and transversely to the length in the case of portion 44. In these cases as the bladder 30 is inflated the folds 40/44 progressively unfold and are drawn out of the interface 34, thereby turning then inside-out.

[0051] A method of use of the present invention will now be described with reference to the drawings.

[0052] in an embodiment, the sheath 12 will protect the bladder 10 from abrasions and puncture as it is inserted into the bore hole 28.

[0053] Referring to Figure 5, the hose and fitting 22 are attached (but are not shown in the figure for simplicity) to the valve 16 and fluid, such as compress air, is inserted into the bladder 30. As shown the closed end portion will inflate. Then as shown in Figure 6, the bladder 30 will inflate down the length of the sheath 12 and this will cause the sheath 12 to expand as permitted by the gussets 15.

[0054] As shown in Figure 7, once the length of the bladder 30 portion which holds the remainder of the bladder 30 folded inside itself is filled the interface 34 will begin to release the remaining portion of the bladder 30 and it will begin to extend in length. The gathered portion will begin to be pulled along inside of the inflated portion of the bladder 30 as shown in Figures 8 and 9. When the inflating bladder 30 reaches the end of the bore hole 28 it will stop with any remaining un-extended portion remaining inside of the inflated portion of the bladder 30.

[0055] The bladder 30 will then fully pressurise to a desired pressure, such that it expands transverse to the length of the bladder 30, that is, diametrically against the wall of the borehole so as to stabilise the wall of the borehole 28. In an embodiment, the bladder is inflated to between about 5psi and about 10 psi. The hose and fitting 22 can then be removed. The valve 16 will stop air from existing the bladder 30.

2018200916 07 Feb 2018 [0056] Modifications may be made to the present invention with the context of that described and shown in the drawings. Such modifications are intended to form part of the invention described in this specification.

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Claims (13)

1. A blast hole stabiliser comprising:

an inflatable bladder for insertion into a blast hole when the bladder is uninflated, wherein the bladder is arranged so that it can be inserted into an appropriately sized blast hole and then inflated, whereby during inflation the bladder expands in length further into and lines the blast hole.

2. A blast hole stabiliser according to claim 1, wherein the bladder is a tube.

3. A blast hole stabiliser according to claim 1 or 2, wherein the bladder is made from airtight and flexible extruded plastic.

4. A blast hole stabiliser according to any one of claims 1 to 3, wherein the majority of the extended length of the bladder is inside of the unextended length of the bladder before it is inflated.

5. A blast hole stabiliser according to any one of claims 1 to 4, wherein a portion of the bladder is configured to be out-side-in prior to being inflated so that as the bladder is inflated and extends in length it turns in-side-out.

6. A blast hole stabiliser according to any one of claims 1 to 5, wherein the bladder is gathered inside itself.

7. A blast hole stabiliser according to any one of claims 1 to 5, wherein the bladder is folded inside itself.

8. A blast hole stabiliser according to any one of claims 1 to 7, wherein the blast hole stabiliser further comprises a protective sheath housing the bladder in its uninflated state.

9. A blast hole stabiliser according to claim 8, wherein the protective sheath is configured such that when the protective sheath is inserted into the opening of a blast hole, the uninflated bladder it also inserted into the blast hole and can then be inflated so as to extend in length further into the blast hole from within the sheath.

10. A blast hole stabiliser according to claim 8 or 9, wherein the protective sheath is made from semi-rigid woven laminated plastic.

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11. A blast hole stabiliser according to any one of claims 8 to 10, wherein the protective sheath is about 1500 mm long.

12. A blast hole stabiliser according to any one of claims 1 to 11, wherein the blast hole stabiliser further comprises a valve for allowing one-way passage of a fluid to inflate the bladder.

13. A method for stabilising blast holes using a blast hole stabiliser, said method comprising:

providing an inflatable bladder tube which is extendable in length when inflated; inserting the bladder into a blast hole and inflating the bladder so that it extends in length further into the blast hole and lines a wall of the blast hole.

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FIG. 12