WO2019113622A1

WO2019113622A1 - In situ shotcrete depth indicator

Info

Publication number: WO2019113622A1
Application number: PCT/AU2018/000245
Authority: WO
Inventors: Dion Michael Johnson
Original assignee: Dion Michael Johnson
Priority date: 2017-12-13
Filing date: 2018-12-04
Publication date: 2019-06-20
Also published as: AU2018382216B2; AU2018382216A1

Abstract

The disclosure relates to shotcreting, and a means for ensuring that a layer of shotcrete has achieved a requisite thickness. In one form, there is provided a shotcrete depth indicator of low cost construction, wherein in use the shotcrete depth indicator is inserted into wet shotcrete to indicate the depth thereof, and where it can remain while the shotcrete cures. In one form, the shotcrete depth indicator comprises a base, an insertion portion for insertion into wet shotcrete, the insertion portion having a length which is greater than or equal to a required shotcrete depth, and at least one barb projecting from the insertion portion for resisting reversal of the insertion portion from the shotcrete.

Description

IN SITU SHOTCRETE DEPTH INDICATOR

PRIORITY DOCUMENTS

[0001] The present application claims priority from Australian Provisional Patent Application No.

2017904999 titled“IN SITU SHOTCRETE DEPTH INDICATOR” and filed on 13 December 2017, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates to shotcreting, and a means for ensuring that a layer of shotcrete has achieved a requisite thickness.

BACKGROUND

[0003] Shotcrete, gunite or sprayed concrete is concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique. It can be reinforced using steel rods, steel mesh, or fibres.

[0004] Following application and an initial period of curing and stiffening, properly designed and applied shotcrete remains in place without sagging even in vertical wall and overhead applications. It is especially suited to areas with restricted access by the use of small portable or mobile equipment.

[0005] In tunnelling and mining, shotcrete can be used either for the final lining or as temporary support as the tunnel or mine is advanced. Shotcrete can be applied in several layers to achieve thicknesses varying from 50 mm to 500 mm.

[0006] Shotcrete is generally applied in layers of approximately 25mm to 50mm (especially when being applied overhead) to prevent fallout. Ideally, the operator should wait ten minutes between layers to ensure adequate set of the first layer before applying the second. Most mining applications require shotcrete thickness of between 50mm and 100mm

[0007] Thickness control is important to ensure that adequate thickness is being achieved. If the layer is too thin, it may lack the requisite strength.

[0008] Methods of thickness control during spraying include using metal probes of a set length permanently mounted on the end of the shotcrete boom to check the depth of the wet shotcrete and the use of stick on depth indicators which may be applied before spraying commences. Both methods have some disadvantages: boom mounted probes can cause damage to delicate boom hydraulics if they are not used carefully, do not provide an indication of excessive thickness and do not provide a permanent record of thickness. Stick on depth indicators are time consuming to apply, are often dislodged by the force of spraying and may be obscured by the spraying.

[0009] Shotcrete thickness can also be measured post spraying. The most common method in use is the drilling and measuring of probe holes. This process requires some time, and there is ample evidence that drilled probe holes provide initiation points for cracking of shotcrete.

[0010] It is against this background and the problems and difficulties associated therewith that the present invention has been developed.

[001 1] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

SUMMARY

[0012] According to a first aspect, there is provided a shotcrete depth indicator of low cost construction, wherein in use the shotcrete depth indicator is inserted into wet shotcrete to indicate the depth thereof, and where it can remain while the shotcrete cures.

[0013] According to a further aspect, there is provided a shotcrete depth indicator comprising a base, and an insertion portion for insertion into wet shotcrete, the insertion portion having a length which is greater than or equal to a required shotcrete depth.

[0014] In one form, the shotcrete depth indicator further comprises at least one barb projecting from the insertion portion, for resisting reversal of the insertion portion from the shotcrete.

[0015] In one from, the shotcrete depth indicator further comprises an outwardly extending flange at the end of the insertion portion, and between the base and the insertion portion.

[0016] In one form, the flange is adapted so that the shotcrete depth indicator can be driven into the wet shotcrete thereby. The flange is so adapted by way of being so sized and sufficiently thick as to possess the requisite strength for this purpose.

[0017] In one form, the base is adapted for nesting within an end of an insertion tool. This nesting facilitates some control and guidance of the shotcrete depth indicator during its insertion into the shotcrete. [0018] The base is so adapted by way of being sized and shaped for this purpose. It should be appreciated that this size and shape may vary depending on the nature of the insertion tool being used.

[0019] In one form, the insertion tool depends from a handpiece for the shotcrete pump.

[0020] In one form, the insertion tool comprises an outlet of a nozzle of the handpiece.

[0021] In one form, the insertion tool is a part of the handpiece separate to the nozzle.

[0022] In one form, the insertion tool comprises a collar in which the insertion tool is received.

[0023] In one form, the shotcrete depth indicator comprises a means for engaging the insertion tool. In use this means will engage the insertion tool sufficient to prevent the shotcrete depth indicator from falling off of the insertion tool once positioned thereon.

[0024] In one form, the means for engaging the insertion tool comprises at least one snap-fit feature extending from the flange of the shotcrete depth indicator.

[0025] In one form, the means for engaging the insertion tool comprises at least one flexible, integral locking feature extending from the flange of the shotcrete depth indicator.

[0026] In one form, the means for engaging the insertion tool comprises at least one flexible, integral cantilever beam extending from the flange of the shotcrete depth indicator.

[0027] In one form, in an alternative, the means for engaging the insertion tool comprises a collar comprising a screw thread or an elastomeric seal.

[0028] In one form, the insertion tool comprises a means for engaging the shotcrete depth indicator. In use this means will engage the shotcrete depth indicator sufficient to prevent the shotcrete depth indicator from falling off of the insertion tool once positioned thereon.

[0029] In one form, the base comprises a locally weakened portion near to the flange. In use, this locally weakened portion will fail in preference to a remainder of the shotcrete depth indicator responsive to impact or shock.

[0030] In one form, the locally weakened portion comprises one or more apertures in the base.

[0031] In one form, the locally weakened portion comprises one or more slots in the base. [0032] In one form, the locally weakened portion comprises one or more slits in the base.

[0033] In one form, the locally weakened portion comprises one or more perforations in the base.

[0034] In one form, the locally weakened portion comprises localised thinning of the base.

[0035] In one form, a distal end of the insertion portion is tapered.

[0036] In one form, the insertion portion comprises a plurality of barbs.

[0037] In one form, a plurality of the barbs are spaced apart lengthwise along the insertion portion.

[0038] In one form, the insertion portion is elongate and comprises a circular cross-section.

[0039] In one form, a plurality of the barbs are radially spaced apart around the insertion portion.

[0040] In one form, the base comprises a cylindrical collar.

[0041] In one form, the base comprises a cross-shaped cross-sectional shape.

[0042] In one form, the base comprises a plurality of stages, where each successive stage extending away from the flange reduces in size.

[0043] The successively smaller stages permit use with insertion collars of different sizes.

[0044] In one form, a shoulder is provided between successive stages.

[0045] In one form, the shotcrete depth indicator is integrally formed. That is to say, it is one piece.

[0046] In one form, the shotcrete depth indicator is made from a plastic material.

[0047] In one form, the shotcrete depth indicator is moulded.

[0048] In one form, in an alternative, the shotcrete depth indicator is manufactured using an additive manufacturing process.

[0049] In one form, the flange comprises at least one through aperture.

[0050] In one form, the flange comprises a plurality of apertures spaced apart there around. [0051] In one form, the or each aperture comprises an arcuate slot.

[0052] In use, the or each aperture assists a user to identify whether or not the flange is in contact with the shotcrete.

[0053] According to a second aspect, there is provided a shotcrete depth indicator comprising a base, an insertion portion for insertion into wet shotcrete, the insertion portion having a length which is greater than or equal to a required shotcrete depth, and at least one barb projecting from the insertion portion for resisting reversal of the insertion portion from the shotcrete.

BRIEF DESCRIPTION OF DRAWINGS

[0054] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein:

[0055] Figure 1 is an isometric view of a shotcrete depth indicator;

[0056] Figure 2 is an end view of the shotcrete depth indicator of Figure 1 ;

[0057] Figure 3 is a side view of a shotcrete depth indicator according to a further embodiment;

[0058] Figure 4 is a detail view taken at Detail B in Figure 3;

[0059] Figure 5 is a forward end view of the shotcrete depth indictor of Figure 3;

[0060] Figure 6 is a cross-sectional view taken at A-A of Figure 3;

[0061] Figure 7 is a side view of a shotcrete depth indicator according to a further embodiment;

[0062] Figure 8 is a detail view taken at Detail A in Figure 7;

[0063] Figure 9 is a forward end view of the shotcrete depth indicator of Figure 7;

[0064] Figure 10 is a cross-sectional view taken at B-B in Figure 7;

[0065] Figure 11 is a cross-sectional view taken at C-C in Figure 7;

[0066] Figure 12 is a cross-sectional view taken at D-D in Figure 7; and [0067] Figure 13 is a cross-sectional view taken at E-E in Figure 7. [0068] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0069] Referring now to Figure 1 , there is shown a shotcrete depth indicator 1 comprising a base 2, and an insertion portion 4 for insertion into wet shotcrete, the insertion portion 4 having a length which is greater than or equal to a required shotcrete depth.

[0070] The insertion portion 4 is elongate, and comprises a circular cross-section and a tapered distal end or nose 6 to aid its insertion in wet shotcrete.

[0071] The shotcrete depth indicator 1 further comprises an outwardly extending flange 8 at the end of the insertion portion 4, between the base 2 and the insertion portion 4.

[0072] The base 2 comprises a cylindrical collar which is sized and shaped to nest within an opening to a collar of an insertion tool, which might comprise an outlet of a nozzle for a shotcrete pump, but may alternatively comprise a tool specific for this purpose and/or separate to the nozzle. The flange 8 then is so sized that an operator can use the insertion tool to push on the flange 8 to drive the insertion portion into the shotcrete.

[0073] The insertion portion 4 further comprises a plurality of barbs 10, for resisting reversal of the insertion portion 4 from the shotcrete.

[0074] The barbs 10 are spaced apart lengthwise along the insertion portion 4. In this embodiment, no two barbs 10 are located at the same position along the insertion portion 4. Moreover, the barbs 10 are radially spaced apart around the insertion portion 4. In this embodiment, no two barbs 10 are located at the same position around the insertion portion 4.

[0075] Each of the barbs 10 is angled away from the nose 6, and undercut so that shotcrete can fill in beneath and behind the barb 10 once the insertion portion 4 is inserted. The barbs 10 then are shaped, sized and arranged to minimise disturbance of the shotcrete during insertion of the insertion portion 4, but provide sufficient resistance to reversal that the shotcrete depth indicator 1 will remain imbedded in the wet shotcrete, even when this shotcrete is overhead.

[0076] The illustrated shotcrete depth indicator 1 is integrally formed from a plastic material by moulding. Other materials and manufacturing techniques could be used, but moulding from plastic facilitates low part cost and high rates of production. Certain minor changes to the depth indicator 1 may be necessary to facilitate moulding, or conversely, a different manufacturing process, such as additive manufacturing, may be employed to make depth indicator 1.

[0077] In use, during a shotcreting operation, an initial layer of shotcrete is applied to the rock surface, and then the base 2 of the shotcrete depth indicator 1 is nested within an opening to a collar of an insertion tool, which might be an outlet of a nozzle for the shotcrete pump (not illustrated), until the flange 8 rests against the end of the nozzle. The insertion tool is then used to push on the flange 8 to drive the insertion portion 4 into the shotcrete until either the tapered nose 6 of the depth indicator 1 hits the rock surface, or the flange 8 comes into contact with the shotcrete. The barbs 10 will ensure that the shotcrete depth indicator 1 does not fall out of the wet shotcrete.

[0078] If the flange 8 meets the shotcrete surface, then no further shotcrete need be applied to this layer of shotcrete.

[0079] If however, the flange 8 sits proud of the shotcrete surface, then this indicates that more shotcrete must be applied to achieve the required thickness. In this case, additional shotcrete is applied until the shotcrete surface meets the flange 8, which is easily visible from where the shotcrete pump operator will be standing.

[0080] It is anticipated that approximately 6 to 9 shotcrete depth indicators will be required per 4.5 meters advance in order to ensure that the requisite shotcrete thickness is achieved across all active headings.

[0081] It is anticipated that a range of depth indicators will likely be required, to facilitate shotcrete layers of varying depths. It is anticipated, for example, that depth indicators with insertion portion lengths of 25mm, 50mm, 100mm, 150mm and 200mm would be useful. Each of these could be moulded from a different high visibility colour, to assist identification and avoid confusion, and in locating them when they are in use.

[0082] Referring now to Figures 3 through 6, where there is illustrated a shotcrete depth indicator 100 according to a further embodiment. Those parts of the shotcrete depth indicator 100 which are identical (or near- identical) to corresponding parts shown in shotcrete depth indicator 1 of Figures 1 and 2, will be denoted by the same reference numerals and will not be described again in detail.

[0083] For shotcrete depth indicator 100, the base 102 comprises a cross-shaped cross-sectional shape X (see Figure 6) comprising four webs 103 arranged at right angles in two pairs. In use, this X-shaped base 102 is nested within a collar of an insertion tool (not illustrated) until the flange 8 rests against the end of the insertion tool. The insertion tool is then used to push on the flange 8 to drive the insertion portion 4 into the shotcrete until either the tapered nose 6 of the depth indicator 1 hits the rock surface, or the flange 8 comes into contact with the shotcrete.

[0084] The barbs 10 of shotcrete depth indicator 100 are not undercut (as in shotcrete depth indicator 1). Instead, a trailing edge of each of these barbs 10 extends normal to a direction of elongation of the insertion portion 4.

[0085] For shotcrete depth indicator 100, the barbs 10 are arranged into pairs, of which there are three such pairs spaced apart along the insertion portion 4. The barbs 10 of each pair are mirrored on the insertion portion 4, and each barb 10 is aligned with one of the webs 103 of the base 102.

[0086] The above described arrangement of the barbs 10 and the cross-shaped base 102 of shotcrete depth indicator 100 more readily facilitates manufacture thereof by plastic injection moulding, where a plane of separation of two mould halves would be aligned with one of the pair of webs 103, and the shape of the trailing edge of the barbs eliminates a potential mould‘hang-up’ point.

[0087] Shotcrete depth indicator 100 further comprises a means 110 for engaging the insertion tool.

[0088] In this embodiment, the means 110 for engaging the insertion tool comprises a pair of flexible, integral cantilever‘snap-fit’ beams 1 12 extending from the flange 8 of the shotcrete depth indicator 100 at diametrically opposing positions on the flange 8. Each of these beams comprises a lug 114 at its distal end, which is intended to aid engagement. Optionally, the insertion tool comprises a recess for receiving each of these lugs 1 14.

[0089] In use, as the webs 103 of the base 102 are inserted within the collar opening of the insertion tool, these beams 1 12 will flex outwardly to permit insertion before returning to engage an outside of the collar sufficient to prevent the shotcrete depth indicator 100 from falling off of the insertion tool once positioned thereon. The beams 112 do not engage the insertion tool so tightly as to pull the depth indicator 100 from the shotcrete as the insertion tool is withdrawn.

[0090] The base 2 of the shotcrete depth indicator 100 further comprises a locally weakened portion 120 near to the flange 8.

[0091] In this embodiment, the locally weakened portion 120 comprises a slot 122 in each of the webs 103 of the base 2. Each of these slots 122 extends inwardly from an outer edge of its respective web 103, to reduce the cross-sectional area of the base 2 between the slots 122, thereby weakening the shotcrete depth indicator 100 at this point. [0092] In use, this locally weakened portion 120 will fail in preference to a remainder of the shotcrete depth indicator 100 responsive to impact or shock, such as the shock wave that is generated when the heading is fired (i.e. explosives are detonated in the rock face).

[0093] Moreover, reinforcing webs 1 16 are provided at the root of the insertion portion 4, where this meets the flange 8, in order to prevent unwanted breakage of the shotcrete depth indicator 100 at this point. These also increase the surface area which is embedded in the shotcrete, thus providing additional resistance to reversal.

[0094] Referring now to Figures 7 through 13, where there is illustrated a shotcrete depth indicator 1000 according to yet a further embodiment. Those parts of the shotcrete depth indicator 1000 which are identical (or near- identical) to corresponding parts shown in shotcrete depth indicator 100 of Figures 3 through 6, will be denoted by the same reference numerals and will not be described again in detail.

[0095] For shotcrete depth indicator 1000, the base 1002 comprises a plurality (four in this case) of stages SI, S2, S3 and S4, where each successive stage SI, S2, S3 and S4 extending away from the flange 8 reduces in size at a step or shoulder 1005. Each of the stages SI , S2, S3 and S4 comprises a cross shaped cross-sectional shape XI, X2, X3 and X4.

[0096] In use, depending on which is closest in size, one of these stages SI , S2, S3 or S4 is nested within a collar of an insertion tool, which might be an outlet of a nozzle for the shotcrete pump (not illustrated), until either the flange 8, or one of the shoulders 1005, rests against the end of the nozzle. The insertion tool is then used to push on the flange 8 or shoulders 1005 to drive the insertion portion 4 into the shotcrete until either the tapered nose 6 of the depth indicator 1 hits the rock surface, or the flange 8 comes into contact with the shotcrete.

[0097] The shotcrete depth indicator allows for permanent determination of correct shotcrete thickness without the need for time consuming and costly drilling and measuring operations, or placing anyone in unnecessary danger beneath thin shotcrete while they perform these operations.

[0098] Throughout the specification and the claims that follow, unless the context requires otherwise, the words“comprise” and“include” and variations such as“comprising” and“including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0099] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge. [00100] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

Claims

1. A shotcrete depth indicator comprising a base, an insertion portion for insertion into wet shotcrete, the insertion portion having a length which is greater than or equal to a required shotcrete depth, and at least one barb projecting from the insertion portion for resisting reversal of the insertion portion from the shotcrete.

2. The shotcrete depth indicator of claim 1, further comprising an outwardly extending flange at the end of the insertion portion, between the base and the insertion portion.

3. The shotcrete depth indicator of claim 2, wherein the flange is adapted so that the shotcrete depth indicator can be driven into the wet shotcrete thereby.

4. The shotcrete depth indicator as in any one of the preceding claims, wherein the base is adapted for nesting within an outlet of an insertion tool.

5. The shotcrete depth indicator as in any one of the preceding claims, wherein a distal end of the insertion portion is tapered.

6. The shotcrete depth indicator as in any one of the preceding claims, wherein the insertion portion comprises a plurality of barbs.

7. The shotcrete depth indicator of claim 6, wherein the barbs are spaced apart lengthwise along the insertion portion.

8. The shotcrete depth indicator as in any one of the preceding claims, wherein the insertion portion is elongate and comprises a circular cross-section.

9. The shotcrete depth indicator of claim 8, wherein the barbs are radially spaced apart around the insertion portion.

10. The shotcrete depth indicator as in any one of the preceding claims, wherein the base comprises a cylindrical collar.

1 1. The shotcrete depth indicator as in any one of the claims 1 through 9, wherein the base comprises a cross-shaped cross-sectional shape.

12. The shotcrete depth indicator of claim 11, wherein the base comprises a plurality of stages, where each successive stage extending away from the flange reduces in size.

13. The shotcrete depth indicator of claim 12, wherein a shoulder is provided between successive stages.

14. The shotcrete depth indicator as in any one of the preceding claims, further comprising a means for engaging the insertion tool.

15. The shotcrete depth indicator of claim 14, wherein the means for engaging the insertion tool comprises at least one snap- fit feature extending from the flange of the shotcrete depth indicator.

16. The shotcrete depth indicator as in any one of the preceding claims, wherein the base comprises a locally weakened portion near to the flange.

17. The shotcrete depth indicator of claim 16, wherein the locally weakened portion comprises one or more apertures in the base.

18. The shotcrete depth indicator as in any one of the preceding claims, wherein the shotcrete depth indicator is integrally formed.

19. The shotcrete depth indicator as in any one of the preceding claims, wherein the shotcrete depth indicator is made from a plastic material.

20. The shotcrete depth indicator as in any one of the preceding claims, wherein the shotcrete depth indicator is moulded.