WO2008144846A1 - Dispositif de formation de vide gonflable pour une utilisation dans des trous de mines explosifs - Google Patents

Dispositif de formation de vide gonflable pour une utilisation dans des trous de mines explosifs Download PDF

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Publication number
WO2008144846A1
WO2008144846A1 PCT/AU2008/000790 AU2008000790W WO2008144846A1 WO 2008144846 A1 WO2008144846 A1 WO 2008144846A1 AU 2008000790 W AU2008000790 W AU 2008000790W WO 2008144846 A1 WO2008144846 A1 WO 2008144846A1
Authority
WO
WIPO (PCT)
Prior art keywords
inflatable
bladder
forming device
void forming
flexible sheath
Prior art date
Application number
PCT/AU2008/000790
Other languages
English (en)
Inventor
Michael John Martin
Original Assignee
Trouperdale Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2007902919A external-priority patent/AU2007902919A0/en
Application filed by Trouperdale Pty Ltd filed Critical Trouperdale Pty Ltd
Publication of WO2008144846A1 publication Critical patent/WO2008144846A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D3/00—Particular applications of blasting techniques
    • F42D3/04—Particular applications of blasting techniques for rock blasting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F42D1/20—Tamping cartridges, i.e. cartridges containing tamping material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F42D1/22—Methods for holding or positioning for blasting cartridges or tamping cartridges
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F42D1/24—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor characterised by the tamping material

Definitions

  • This invention is concerned with a method and apparatus for forming voids in an explosives composition.
  • the invention is concerned particularly, although not exclusively, with an inflatable device for forming a void in a column of explosive composition in a borehole.
  • these inflatable bladders fall into two groups of which one group comprises sealed bladders with a selectively actuable expandable fluid generating device sealed within the bladder and the other group comprises an externally inflatable bladder having a valve to which an air hose or the like is detachably connected.
  • Australian Patents 579395 and 595887 describe selectively mixable co-reagents which react to form, respectively, an expandable polyurethane foam and a gas within the bladder.
  • Australian Patent 656051 describes a bladder inflation device with a time delay mechanism which relies on exhaustion of a liquid through a narrow nozzle before an expandable gas can escape.
  • 5,035,286 and 5,273,100 each describe externally inflatable bladders having a self-sealing nozzle detachably connectable to an air hose.
  • the inflatable bladders are lowered into boreholes by the air hose and, at a desired depth, a source of pressurized air is introduced to inflate the bladders firmly against the wall of the borehole.
  • a rock blasting method described in WO 01/20248 utilizes an externally inflatable cylindrical air tube which forms an air decking to support layers of explosives composition and stemming material as a means of reducing the number of detonators required in a given blast pattern.
  • United States Patent 6,631 ,684 describes the use of inflated cylindrical tubes having a diameter less than that of the borehole so that when surrounded by a flowable explosives composition such as ANFO, the inflated tube formed a void within the column of explosive which reduced the quantity of explosive required.
  • a centering device having radially projecting arms was proposed, but it was considered that these centering devices would prevent precise location of the void forming tubes and actually add to the risk of incomplete detonation.
  • a difficulty with the aforementioned inflatable void formers is that they are required to be inflated before insertion into a borehole and thus, to overcome frictional forces between the wing-like formations and the bore hole wall, a mass such as stemmings, sand or earth must be introduced into a specially fabricated pocket to enable the void former to proceed down the borehole without jamming.
  • the mass of explosive composition and stemmings above the cylinder can be sufficient to cause the inflated cylinder to kink and partially collapse within the borehole thereby constricting the volume of explosive in the region of the partial collapse with a consequent risk of forming a discontinuity in the explosive column.
  • an inflatable void forming device for use in explosives boreholes comprising: an elongate inflatable bladder fabricated from a flexible polymeric film; and a flexible sheath of stretch resistant material, the flexible sheath, in use, resisting an increase in volume of the bladder when the bladder is pressurized to a predetermined degree.
  • the flexible sheath is comprised of a stretch resistant polymeric film.
  • the stretch resistant polymeric film may comprise a laminate or multi-layer construction including a stretch resistant substrate.
  • the stretch resistant polymeric film comprises an aluminium substrate.
  • the inflatable bladder is fabricated from a polyolefin, polyester, polyamide, polyurethane, vinyl or copolymers, co-extrusions or laminates thereof.
  • the inflatable bladder is an elongate inflatable tubular bladder.
  • the inflatable bladder may comprise a gas-tight sealed chamber containing a selectively actuable container of expansible fluid.
  • said inflatable tubular bladder may comprise a gas-tight sealed chamber comprising an inflation valve to permit inflation with an external source of pressurized fluid.
  • the flexible sheath may be comprised of a high tensile strength plastics film.
  • the flexible sheath is comprised of a woven or non-woven fabric selected from the group consisting of polyolefins, polyesters, polyamides, polyurethanes, glass, carbon or KevlarTM fibres.
  • said flexible sheath has antistatic properties.
  • said void forming device may include a layer of heat reflective material intermediate said inflatable bladder and said flexible sheath.
  • a method of forming voids in a column of explosives composition in a borehole comprising the steps of:- inflating, to a predetermined pressure, a void forming device comprising an elongate inflatable bladder fabricated from a flexible polymeric film, the bladder being located within a flexible stretch resistant sheath whereby, in use, the stretch resistant sheath resists an increase in volume of the bladder when pressurized to a predetermined degree; inserting the inflated void forming device into a borehole having a diameter greater than said void forming device; and introducing into said borehole, a quantity of flowable explosives composition to surround said void forming device, thereby forming a void in a column of explosives composition within said borehole.
  • FIG. 1 shows an inflatable tubular bladder
  • FIG. 2 shows a void forming device according to the invention
  • FIG. 3 shows an enlarged view of an inflation valve associated with said tubular bladder
  • FIG. 4 shows a cross-sectional view of a borehole containing a column of explosives composition surrounding a void forming device.
  • the inflatable bladder 1 may be formed as an elongate hollow body 2 by thermally fusing two sheets of a thermoplastic film about the perimetral edge 3 of body 2.
  • the bladder 1 is formed from lay flat tubing with transverse thermal welds at opposite ends.
  • An inflation valve 4 is sealed into body 2 by a transverse thermal weld 5 at the top of body 2 and a similar weld 5a forms a closure at the bottom of the body.
  • body 2 assumes a tubular configuration with generally rounded ends 6, 7 to withstand inflation pressures of up to 100 psi without placing undue stress on welds 5, 5a.
  • Other shapes are, of course, possible but the tubular configuration shown in FIG. 1 is preferred to lessen the risk of the borehole becoming blocked.
  • thermoplastic film from which bladder 1 is fabricated may be selected from polyolefins, polyamides, polyurethanes, polyesters, vinyls or any other suitable plastics films.
  • the polymeric compounds may be monomeric or polymeric and the films thereof may be co-extruded or laminated.
  • Polyethylene terephthalate (PET) is a particularly preferred film for this purpose.
  • FIG. 2 shows a void forming device 1a according to the invention in an inflated state.
  • a bladder of the type shown in FIG. 1 is encased in a sheath 8 of a tough stretch and puncture resistant material such as a woven polypropylene fabric.
  • Other stretch resistant materials may include axially stretched polymeric films, knitted, woven or non-woven fabrics of polymeric materials, glass fibre, carbon fibre, KEVLARTM or like high tensile fibres, natural fibres such as cotton, jute, hemp and the like or mixtures thereof.
  • An opening 9 is provided in the top of sheath 8 to accommodate inflation valve 4.
  • the sheath 8 will be designed to be of a size such that, in operation, it allows the bladder 1 to be inflated, and hence to expand, to the desired level but physically restricts the volume to which the bladder 1 is able to expand beyond this point. This is achieved by the sheath 8 being formed from a stretch resistant material.
  • the stretch resistant material is sized so as restrict bladder 1 from expanding to fill the entire borehole or increasing its volume such that its internal pressure becomes undesirably low.
  • valve 4 (not shown) coupled to a source of compressed air is inserted into valve 4 and the bladder is inflated to a predetermined pressure of between say, 60 psi and 100 psi, depending upon such factors as the depth of the borehole.
  • a predetermined pressure of between say, 60 psi and 100 psi, depending upon such factors as the depth of the borehole.
  • FIG. 3 shows an enlarged view of the valve 4.
  • Valve 4 is a flat elongate tubular member formed either as a lay flat tube by extrusion or otherwise formed by two strips of plastics flim, thermally fused along longitudinal edges 4a with upper and lower ends 10, 11 both being open.
  • the valve tube 4 is placed between the two sheets of film forming the body 2 before the upper end of body 2 is sealed by thermal welding along weld seam 5.
  • the valve tubing 4 is selected from a polymeric material compatible with the body film to ensure air tight integrity.
  • valve 4 With a tapered air hose nozzle frictionally engaged in the opening 13, air is introduced until a desired bladder pressure is achieved whereupon the valve is withdrawn. Internal pressure acting on the relatively long internal tail 4b of valve 4 urges the two layers of plastics film into close contact with each other thereby forming an effective self-sealing valve 4.
  • FIG. 4 shows the mode of use of the void forming devices according to the invention.
  • a borehole 15 is filled to a predetermined depth 16 with a flowable explosives composition such as ANFO.
  • a void forming device 1a of the type described above is then inflated to a predetermined pressure, say, 80 psi and is dropped down the borehole where typically it will be supported at its base on the surface 16 of the initial ANFO charge 17 and inclined against the borehole wall 18.
  • the inflatable bladder 1 within the void former will be in intimate contact over its external surface (apart from the valve area) with the internal surface of stretch resistant sheath 8 to prevent unwanted volume expansion of bladder 1 and thereby maintain the internal pressure within a set range.
  • a second charge 19 of ANFO is then introduced into the borehole 15 whereby it completely surrounds the void forming device except perhaps for the region 21 where the upper end of the void forming device 1a is in contact with the borehole wall 18.
  • the mass of explosives composition does not, at any point along its length, form a region less than the critical diameter of the composition to ensure full propagation of explosive forces within the borehole.
  • the process may be repeated to have a plurality of void formers spaced throughout the borehole and otherwise encased in explosives composition.
  • inflated void formers may be introduced along with the ANFO at predetermined intervals representing a desired spacing between void formers in the borehole.
  • the sheath 8 may be adapted to possess antistatic properties to avoid the build up of triboelectrically generated static charges which could cause a spark sufficient to activate the NONEL detonating tube 20 within the borehole.
  • the sheath fabric may be coated with a proprietary antistatic fabric spray, or the sheath material may be fabricated from or include electrically conductive fibres.
  • the void forming device may include an intermediate layer of aluminized MYLARTM film between the inner bladder and the outer sheath to form a thermal barrier.
  • the bladder 1 may be formed as a gas-tight sealed chamber within which is located an aerosol can of expansible fluid selectively releasable upon manual activation of a valve actuator by pressure applied from outside the sealed chamber.
  • a suitable container of expansible fluid is described in Australian Patent 779463, the contents of which are incorporated herein by reference.
  • the inner bladder is inflated until it fully occupies the stretch resistant sheath 8.
  • a predetermined bladder pressure may be achieved by selecting an appropriate volume of expansible material for the volume of the bladder or otherwise by adapting the composition of the expansible fluid such that the vapour pressure of the expansible fluid reaches equilibrium at a predetermined bladder pressure.
  • the bladder 1 and sheath 8 may be manufactured from a translucent or, preferably, transparent material, particularly when an aerosol can is used as the inflation device. This allows the actuator mechanism of said aerosol to be more conveniently located and actuated by the user.
  • the materials from which the inflatable bladder 1 and sheath 8 are constructed from, respectively may be manufactured in a form such that they are laminated together.
  • a large sheet of the laminate is rolled out which may have the material to form the bladder 1 in a lay flat tubing-like form as previously described with the sheath material pre-formed to surround it.
  • the shape of the void former 1a is cut out in a single press using a welding plate or the like. The welding plate would be such that, as the void former 1 a is cut out of the laminate the open edges are thermally sealed apart from a small opening for the valve which is formed substantially as described in relation to FIG. 3.
  • the laminate cut out would be sealed as before but leaving an opening for insertion of the aerosol can after which time this opening would also be sealed.
  • the laminate is such that the inflatable bladder 1 can still be inflated by the desired degree before its walls come into restrictive contact with the sheath 8 and further expansion of the bladder 1 is thereby prevented.
  • a laminate of this kind can provide advantages in ease and speed of manufacture by allowing a number of void formers 1a to be "stamped out" from one large piece of laminate. It should now be understood that the present invention provides for an inflatable device for forming a void in a column of explosives composition in a borehole.
  • the device is comprised of an inflatable bladder made from a plastics material which can be inflated to a desired pressure and volume.
  • the bladder is encased in a sheath of a stretch and puncture resistant material which prevents the bladder from continuing to expand over time after active inflation has ceased due to the pressure placed upon the plastics material by the inflation fluid.
  • the sheath forms a physical barrier to the continuing expansion of the bladder beyond the desired volume as once the bladder stretches to contact and press against the internal surface of the sheath its stretch resistant nature will restrict any further expansion.
  • a void former which can be inflated to a desired pressure to form the required void volume within an explosives composition which will not further increase its volume significantly and therefore will not completely fill the borehole diameter, will be less likely to collapse under the load due to its inflation pressure being maintained and will be protected from rocks and other sharp objects in the borehole by the tough sheath.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Tents Or Canopies (AREA)

Abstract

L'invention concerne un dispositif de formation de vide gonflable pour former un vide dans une colonne d'une composition d'explosifs dans un trou de mine. Le dispositif comprend une vessie gonflable allongée fabriquée à partir d'un film polymère flexible et une gaine flexible de matériau résistant à l'étirement. La gaine flexible, pendant l'utilisation, peut résister à une augmentation indésirable du volume de la vessie après que la vessie a été pressurisée à un degré prédéterminé.
PCT/AU2008/000790 2007-05-31 2008-06-02 Dispositif de formation de vide gonflable pour une utilisation dans des trous de mines explosifs WO2008144846A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2007902919A AU2007902919A0 (en) 2007-05-31 Void former
AU2007902919 2007-05-31

Publications (1)

Publication Number Publication Date
WO2008144846A1 true WO2008144846A1 (fr) 2008-12-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2008/000790 WO2008144846A1 (fr) 2007-05-31 2008-06-02 Dispositif de formation de vide gonflable pour une utilisation dans des trous de mines explosifs

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015155418A1 (fr) * 2014-04-10 2015-10-15 Normet Oy Procede et agencement pour fournir un chargement d'explosif dans un trou de forage
CN108894745A (zh) * 2018-09-19 2018-11-27 重庆科技学院 一种岩石钻孔口气压封堵装置及方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4492165A (en) * 1983-08-08 1985-01-08 C-I-L Inc. Expandable explosive and stemming cartridge
US5273110A (en) * 1992-07-22 1993-12-28 Fitzgibbon Jr Daniel F Inflatable devices for suspending explosives and stemming materials in boreholes
WO2001004565A1 (fr) * 1999-07-14 2001-01-18 Koen Alixe Mauritz Dhooge Bouchon pour trou de mine
US6502631B1 (en) * 2001-06-04 2003-01-07 Daniel F. Fitzgibbon Reinforced borehole plugs

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4492165A (en) * 1983-08-08 1985-01-08 C-I-L Inc. Expandable explosive and stemming cartridge
US5273110A (en) * 1992-07-22 1993-12-28 Fitzgibbon Jr Daniel F Inflatable devices for suspending explosives and stemming materials in boreholes
WO2001004565A1 (fr) * 1999-07-14 2001-01-18 Koen Alixe Mauritz Dhooge Bouchon pour trou de mine
US6502631B1 (en) * 2001-06-04 2003-01-07 Daniel F. Fitzgibbon Reinforced borehole plugs

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015155418A1 (fr) * 2014-04-10 2015-10-15 Normet Oy Procede et agencement pour fournir un chargement d'explosif dans un trou de forage
US9846020B2 (en) 2014-04-10 2017-12-19 Normet Oy Method and arrangement for providing explosive charging into a bore hole
CN108894745A (zh) * 2018-09-19 2018-11-27 重庆科技学院 一种岩石钻孔口气压封堵装置及方法
CN108894745B (zh) * 2018-09-19 2024-01-30 重庆科技学院 一种岩石钻孔口气压封堵装置及方法

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