AU2008202945B2

AU2008202945B2 - Rock face support device

Info

Publication number: AU2008202945B2
Application number: AU2008202945A
Authority: AU
Inventors: David William Evans; Derek Colin Hird
Original assignee: DSI Underground Australia Pty Ltd
Current assignee: DSI Underground Australia Pty Ltd
Priority date: 2007-07-27
Filing date: 2008-07-03
Publication date: 2013-10-03
Anticipated expiration: 2028-07-03
Also published as: AU2008202945A1

Abstract

ROCK FACE SUPPORT DEVICE Abstract A rock face support device (100) has a washer (101) having a mounting aperture (106) extending therethrough for receipt of a rock bolt. A mesh element (102) is formed 5 of two interlocking series of rods (107) defining a plurality of openings (108) therebetween. The mesh element (102) has a primary portion (110) lying generally in a first plane (P1) and a recessed portion lying generally in a second plane (P2) offset in relation to said first plane (P1). The recessed portion (111) includes one opening (108) having a closed boundary (114) defined by four rods (109). The washer (101) is fixed to 1o the mesh element (102) within the recessed portion (111) and overlaps the closed boundary (114) on all sides thereof. The mounting aperture (106) is aligned with the one opening (108). The washer (101) is located on a face of the recessed portion (111) facing the first plane (P1). The mesh element (102) may have one or more peripheral portions (115) inclined in relation to the primary portion (110) extending away from the first plane is (P1) toward the second plane (P2). Each pair of adjacent rods (107) located closest to an edge of the mesh element (102) may be spaced more closely than each other pair of adjacent rods (107). (03 tlot

Description

S&F Ref: 864927 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address DYWIDAG-Systems International Pty Limited, of Applicant: an Australian company, ACN 093 424 349, of 25 Pacific Highway, Bennett's Green, New South Wales, 2290, Australia Actual Inventor(s): David William Evans, Derek Colin Hird Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Rock face support device Associated Provisional Application Details: [33] Country: [31] Appl'n No(s): [32] Application Date: AU 2007904076 27 Jul 2007 The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(1 300610_1) 1 ROCK FACE SUPPORT DEVICE Technical Field The present invention relates to the field of strata control products and particularly relates to a rock face support device. s Background of the Invention The roofs and walls of mines, tunnels and other underground excavations are often stabilised with the use of rock bolts secured in bore holes drilled into the rock face. In various applications the rock face itself is stabilised with a layer of concrete or mortar that is sprayed directly onto the rock face by a process known as the shotcrete process. 10 To assist in securing the concrete layer to the rock face, it is known to embed within the concrete layer a series of support devices, such as plates and/or wire mesh, that are each secured to the trailing end of a rock bolt. One previously proposed form of such a support device consists of a plate washer secured to a steel mesh element, with the plate washer offset from the plane of the 15 bulk of the mesh element with the intention that the mesh element will remain offset from the rock face and thereby embedded within the concrete layer. The previously proposed device, however, may be subject to having the plate washer pull through the mesh element if the welds joining the mesh element to the plate washer fail, so that the mesh element no longer remains secured to the rock bolt. Further, 20 in applications where the mesh element is not installed perpendicular to the rock face, or the rock face is uneven, substantial portions of the mesh element may lie immediately adjacent the rock face such that it is not sufficiently embedded within the concrete layer. The mesh elements may also be subject to deformation during installation in such applications. 25 Object of the Invention It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages.

2 Summary of the Invention In a first aspect, the present invention provides a rock face support device comprising: a washer having a mounting aperture extending therethrough for receipt of a rock s bolt; and a mesh element formed of two interlocking series of rods defining a plurality of openings therebetween, said mesh element having a primary portion lying generally in a first plane and a recessed portion lying generally in a second plane offset in relation to said first plane, said recessed portion including one said opening having a closed 10 boundary defined by four of said rods, said washer being fixed to said mesh element within said recessed portion and overlapping said closed boundary on all sides thereof with said mounting aperture being aligned with said one opening, said washer being located on a face of said recessed portion facing said first plane. Typically, said recessed portion is located centrally of said mesh element. 15 In one form, said primary portion surrounds said recessed portion. In another form, said recessed portion extends between two opposing edges of said mesh element, with said primary portion lying on two opposing sides of said recessed portion. Typically, said rods of each said series are arranged in generally parallel 20 relationship. Typically, said two series are arranged in a generally perpendicular relationship. In a preferred form, one or more peripheral portions of said mesh element is/are inclined in relation to said primary portion, extending away from said first plane toward said second plane. 25 Preferably, said mesh element is generally rectangular and one said peripheral portion is defined at each corner of said mesh element. In one form, each pair of adjacent said rods located closest to an edge of said mesh element is spaced more closely than each other pair of adjacent said rods. In a second aspect, the present invention provides a rock face support device 30 comprising: a washer having a mounting aperture extending therethrough for receipt of a rock bolt; and 3 a mesh element formed of two interlocking series of rods defining a plurality of openings therebetween, said mesh element having a primary portion lying generally in a first plane, a recessed portion lying generally in a second plane offset in relation to said first plane and one or more peripheral portions inclined in relation to said primary portion 5 extending away from said first plane toward said second plane, said washer being fixed to said mesh element within said recessed portion and located on a face of said recessed portion facing said first plane. Preferably, said mesh element is generally rectangular and one said peripheral portion is defined at each corner of said mesh element. 10 Typically, said rods of each said series are arranged in generally parallel relationship. Typically, said two series are arranged in a generally perpendicular relationship. In one form, each pair of adjacent said rods located closest to an edge of said mesh element is spaced more closely than each other pair of adjacent said rods. 15 In a third aspect, the present invention provides a rock face support device comprising: a washer having a mounting aperture extending therethrough for receipt of a rock bolt; and a mesh element formed of two interlocking series of rods defining a plurality of 20 openings therebetween, said mesh element having a primary portion lying in a first plane and a recessed portion lying generally in a second plane offset in relation to said first plane, said washer being fixed to said mesh element within said recessed portion and located on a face of said recessed portion facing said first plane; wherein each pair of adjacent said rods located closest to an edge of said mesh 25 element is spaced more closely than each other pair of adjacent said rods. Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings wherein: Figure 1 is an exploded isometric view from above of a rock face support device; 30 Figure 2 is an isometric view from above of the rock bolt support device of Figure 1; Figure 3 is an isometric view from below of the rock face support device of Figure 1; 4 Figure 4 is a front elevation view of the rock face support device of Figure 1; Figure 5 is a plan view of the rock face support device of Figure 1; Figure 6 is a plan view of the mesh element of the rock face support device of Figure 1; 5 Figure 7 is a cross-sectional view of a rock face support installation utilising the rock face support device of Figure 1; Figure 8 is an isometric view from above of a alternate rock face support device; Figure 9 is an isometric view from above of a further alternate rock face support device; and to Figure 10 is a front elevation view of the rock face support device of Figure 9. Detailed Description of the Preferred Embodiments Referring to Figures 1 to 6 of the accompanying drawings, a rock face support device 100 comprises a washer 101 and a mesh element 102. Figure 1 is an exploded view, depicting the washer 101 mesh element 102 separated. 15 The washer 101 is a standard plate washer in the form of a square plate portion 103 and centrally located frustoconical boss 104. The boss 104 has an annular rim 105 defining a mounting aperture 106 extending through the washer 101 for receipt of a rock bolt in the usual manner. The mesh element 102 is formed of two interlocking series of rods 107 defining 20 a plurality of openings 108 therebetween. The rods 107 are typically formed of low carbon steel and interlocked by tack welding at the junction 109 of interlocking rods 107 of each series. The mesh element 102 has a primary portion 110 lying generally in a first plane P1 (see Figure 4) and a recessed portion 111 lying generally in a second plane P2 (again see Figure 4) that is offset in relation to the first plane P1, here by about 30 mm. 25 Whilst the primary portion 110 and recessed portion 111 lie generally in their respective first and second planes P1, P2 it is not necessary that these portions be strictly planar. The recessed portion 111 is offset relative to the primary portion 110 by virtue of a series of two right angled bends forming a "dog-leg" 112 in those rods 107 that pass through the recessed portion 111 at the junction between the primary portion 110 and recessed portion 30 111. The rods 107 of each series is also arranged in a parallel relationship and the two series are arranged in a generally perpendicular relationship, although alternate relative orientations may be utilised if so desired.

5 The recessed portion 111 includes one opening 113 having a square, closed boundary 114 that is defined by four of the rods 107. Typically this opening 113 is located in the centre of the recessed portion 111 which is itself located centrally of the mesh element 102. The washer 101 is fixed to the mesh element 102 within the recessed 5 portion 111, typically by tack welds between the rear face of the plate portion 103 of the washer 101 and the two overlying rods 107 defining opposing sides of the closed boundary 114 of the central opening 113. The washer 101 is sized and located such that it overlaps the closed boundary 114 around all sides thereof, with the mounting aperture 106 being aligned with the central opening 113 to enable a rock bolt to pass therethrough. 10 Having the washer 101 overlap the closed boundary 114 around all sides thereof prevents the washer 101 from being pulled through the central opening 113. The washer 101 is located on the uppermost face of the recessed portion 111, being that face which faces the first plane Pl. In the rock face support device depicted in Figures 1 to 6, the primary portion is 110 surrounds the recessed portion 111 on all four sides thereof, with the recessed portion 111 being a square shape to match the square washer 101. The mesh element 101 is of a generally rectangular form, specifically a square form. Peripheral portions 115 of the mesh element 101 defined at each corner of the mesh element are bent over so as to be inclined in relation to the primary portion 110, 20 forming "dog-ear" like flanges 115 at each corner of the mesh element 101. The flanges 115 extend away from the first plane P1 toward the second plane P2, as best depicted in Figure 4. Specifically, the flanges 115 extend approximately to the second plane P2, such that the recessed portion 111 and the tip 116 of each flange 115 generally lie in the second plane P2. The flanges 115 assist in keeping the primary portion 110 offset from the rock 25 face during use, as will be discussed below. In the particular configuration of the rock face support device 100 depicted, each series of rods 107 comprises six parallel rods 107 such that there is an array of 5 x 5 openings 108. The four edge regions of the mesh element 101 are effectively reinforced by having each pair of adjacent rods 107 located closest to each edge 117 spaced more 30 closely than each remaining pair of adjacent rods, located away from the edge 117. In the particular arrangement depicted, each pair of rods 107 located closest to an edge 117 of the mesh element 101 is spaced by approximately 50 mm, whilst the remaining pairs of rods 107 are spaced by approximately 100 mm. The mesh element 101 thus has an 6 overall size of approximately 400 x 400 mm. Individual rods 107 are typically formed of hard drawn low carbon steel with a diameter of the order of 5 mm. Use of the rock face support device 100 will now be described with reference to Figure 7. A series of bore holes I are drilled into the rock face 2 to be stabilised in the 5 usual manner. A rock face support device 100 is then located against the rock face 2 such that the mounting aperture 106 is aligned with the bore hole 1, with the recessed portion Ill held directly against the rock face 2. A rock bolt, which may take the form of a known friction rock stabiliser bolt 3, or any other known form of rock bolt, is then installed through the mounting aperture 106 into the bore hole I and secured therein by 10 any of various known means. The collar 4 of the rock bolt 3 engages the annular rim 105 of the washer 101, sandwiching the recessed portion 111 between the washer 101 and the rock face 2. The offset between the recessed portion 111 and primary portion 110 provides an offset between the rock face 2 and the primary portion 110. The flanges 115 assist in is maintaining this offset if the mesh element 102 is not installed parallel to the rock face 2 or if the rock face 2 is particularly uneven. The tip 116 of each flange 115 engages the rock face 2 if the rock face 2 projects beyond the second plane P2 in which the recessed portion 111 lies, thereby forcing the primary portion 110 to deform away from the rock face 2, maintaining the offset between the primary portion 110 and the rock face 2. The 20 reinforcing provided by the closer spacing between the rods 107 adjacent each edge 117 assists in ensuring that the deformation of the primary portion 110, resulting from force applied by the rock face 1 to the flange 115, does not provide a localised large deformation of the primary portion 110 immediately adjacent the flange 115 but provides a more even deformation over a larger region of the primary portion 110, keeping it offset 25 from the rock face 2. Once rock bolts 3 and associated rock face support devices 100 have been installed over a given area, the rock face 2 in that area is sprayed with a layer 5 of concrete, using the shotcrete process, to a desired thickness sufficient to ensure that the primary portion 110 of each rock face support device 100 is embedded within the 30 concrete layer 5, so as to adequately secure the immediate region of the concrete layer 5 to the rock face 2. Figure 8 depicts a first alternate rock face support device 100' comprising a washer 101 identical to that discussed above, and a modified mesh element 102'. The modified mesh element 102' is identical to the mesh element 101 described above in 7 relation to Figures 1 to 6, with the omission of the inclined peripheral portions defining flanges at the corners of the mesh element, and with equidistant spacing between all rods 107, rather than utilising closer spacing around the edge regions of the mesh element. It is envisaged that flanges may be added to the modified mesh element 102' in the same 5 manner as discussed above, or alternatively that the edge regions may be reinforced, again in the same manner as discussed above in relation to the configuration of Figures 1 to 6. Figures 9 and 10 depict a further alternate rock face support device 100" again utilising the same washer 101 but with a further modified mesh element 102". In the configuration depicted in Figures 9 and 10, the recessed portion 111" is in the form of a io channel extending between opposing side edges 117 of the mesh element 102", with the primary portion 110" being divided into two and lying on two opposing sides of the recessed portion 111". Whilst this configuration does not provide as great a proportion of the mesh element 102" lying in the plane P1 offset from the rock face, it is typically more cost effective to manufacture. Again, this further modified mesh element 102" is could be provided with flanges at each corner thereof in a similar manner to the configuration described above in relation to Figures 1 to 6, and again, if desired, the edge regions could be reinforced with closer spacing between pairs of rods adjacent each edge of the modified mesh element 102". A person skilled in the art will appreciate various other possible modifications of 20 the above described rock face support devices.

Claims

1. A rock face support device comprising: a washer having a mounting aperture extending therethrough for receipt of a rock bolt; and 5 a mesh element formed of two interlocking series of rods defining a plurality of openings therebetween, said mesh element having a primary portion lying generally in a first plane and a recessed portion lying generally in a second plane offset in relation to said first plane, said recessed portion including one said opening having a closed boundary defined by four of said rods, said washer being fixed to said mesh element 1o within said recessed portion and overlapping said closed boundary on all sides thereof with said mounting aperture being aligned with said one opening, said washer being located on a face of said recessed portion facing said first plane.

2. The device of claim 1, wherein said recessed portion is located centrally of said mesh element. 15

3. The device of claim 2, wherein said primary portion surrounds said recessed portion.

4. The device of claim 1, wherein said recessed portion extends between two opposing edges of said mesh element, with said primary portion lying on two opposing sides of said recessed portion. 20

5. The device of any one of claims I to 4, wherein said rods of each said series are arranged in generally parallel relationship.

6. The device of claim 5, wherein said two series are arranged in a generally perpendicular relationship.

7. The device of any one of claims I to 6, wherein one or more peripheral 25 portions of said mesh element is/are inclined in relation to said primary portion, extending away from said first plane toward said second plane.

8. The device of claim 7, wherein said mesh element is generally rectangular and one said peripheral portion is defined at each corner of said mesh element. 30 9. The device of any one of claims I to 8, wherein each pair of adjacent said rods located closest to an edge of said mesh element is spaced more closely than each other pair of adjacent said rods.

9

10. A rock face support device comprising: a washer having a mounting aperture extending therethrough for receipt of a rock bolt; and a mesh element formed of two interlocking series of rods defining a plurality of 5 openings therebetween, said mesh element having a primary portion lying generally in a first plane, a recessed portion lying generally in a second plane offset in relation to said first plane and one or more peripheral portions inclined in relation to said primary portion extending away from said first plane toward said second plane, said washer being fixed to said mesh element within said recessed portion and located on a face of said recessed 1o portion facing said first plane.

11. The device of claim 10, wherein said mesh element is generally rectangular and one said peripheral portion is defined at each corner of said mesh element.

12. The device of either of claims 10 and 11, wherein said rods of each said is series are arranged in generally parallel relationship.

13. The device of claim 12, wherein said two series are arranged in a generally perpendicular relationship.

14. The device of any one of claims 10 to 13, wherein each pair of adjacent said rods located closest to an edge of said mesh element is spaced more closely than each 20 other pair of adjacent said rods.

15. A rock face support device comprising: a washer having a mounting aperture extending therethrough for receipt of a rock bolt; and a mesh element formed of two interlocking series of rods defining a plurality of 25 openings therebetween, said mesh element having a primary portion lying in a first plane and a recessed portion lying generally in a second plane offset in relation to said first plane, said washer being fixed to said mesh element within said recessed portion and located on a face of said recessed portion facing said first plane; wherein each pair of adjacent said rods located closest to an edge of said mesh 30 element is spaced more closely than each other pair of adjacent said rods. 10

16. A rock face support device substantially as hereinbefore described with reference to Figures I to 6, Figure 8 or Figures 9 and 10 of the accompanying drawings. Dated 3 July, 2008 DYWIDAG-Systems International Pty Limited Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON