MESH

Field

[0001] The present invention relates to strata control in civil engineering and mining operations and in particular relates to an apparatus and method for installing a reinforcing mesh for supporting the roof or wall surface of a mine, tunnel or other ground excavation.

Background

[0002] Rock faces forming the roof or wall of mines, tunnels or other ground excavations are typically secured with the use of rock bolts in conjunction with reinforcing mesh sheets. Rock bolts, which may be in the form of a rigid steel bar or flexible steel strand, are secured into bore holes drilled through the rock face and consolidate and reinforce the rock strata. Mesh sheets extend across the rock face to locally confine the rock surface and prevent small fragments of rock from falling down and endangering occupants of the mine or tunnel.

[0003] The mesh sheets are typically secured against the rock face by being sandwiched between the rock face and the plate washer associated with each rock bolt that acts to transfer load between the rock bolt and die rock face.

[0004] The mesh sheets are typically in the form of welded steel wire mesh, formed in sheets with a length of the order of 2 to 6 m and a width of 0.5 to 2.4 m that can be manually handled and installed. The size of the sheets is generally limited by the fact that the mesh sheets are relatively rigid and heavy, with the wire elements forming the mesh typically having a diameter of the order of 4 to 6 mm.

[0005] To install a mesh sheet, the mesh sheet is typically manually held against the rock face whilst a series of bore holes are drilled into the rock face through the apertures in the wire mesh sheet and rock bolts are subsequently installed into the bore holes. The plate washers that secure the trailing head of each rock bolt against the rock face engage the wire elements of the mesh about the aperture through which the rock bolt is installed, sandwiching the wire mesh sheet between the plate washer and the rock face, thereby securing the mesh sheet against the rock nice.

[0006] The rock bolts are typically installed in a square or rectangular pattern along the length and width, of each mesh sheet, and the full rock face is confined by a series of overlapping mesh sheets arranged side by side and end to end as required.

Summary of Invention

[0007] In a first aspect the present invention provides an apparatus for installing a reinforcing mesh to secure a rock face, said apparatus comprising:

a support frame having a plurality of frame elements defining a frame face of said support frame;

a plurality of locating elements each mounted on said support frame and projecting from said frame lace, each of said locating elements being configured to extend through an aperture of a reinforcing mesh to be installed; and

a mount on said support frame configured to be mounted to a support arm.

[0008] In a preferred form, each of said locating elements comprises a pin.

[0009] In a preferred form, at least some of said locating elements are spaced along a periphery of said support frame.

[0010] In one form, at least some of said locating elements are removably mounted on said support frame.

[0011] A method of installing a reinforcing mesh to secure a rock face, said method comprising the steps of:

a) mounting a reinforcing mesh on the frame lace of the apparatus defined above with each of said locating elements extending through an aperture of said reinforcing mesh;

b) locating said support frame and reinforcing mesh adjacent the rock face;

c) drilling a plurality of boreholes into the rock face;

d) installing a plurality of rock bolts, each into one of said boreholes; e) securing said reinforcing mesh against the rock face by a plate washer mounted on each of said rock bolts, with said rock bolts extending through apertures of said reinforcing mesh, such that said reinforcing mesh is secured between said plate washers and the rock face; and

f) withdrawing said apparatus from the rock face and said reinforcing mesh.

[0012] Typically, step b) is carried out prior to step c), each of said boreholes being drilled through an aperture of said reinforcing mesh.

[0013] Alternatively, step c) may be carried out before step b).

[0014] Typically, step b) is carried out before step d).

[0015] In an alternative method, step d) is carried out before b).

[0016] In one form of such an alternative method, a first plate washer is mounted on each said rock bolt during step c), a second plate washer being mounted on each of said rock bolts during step e) such that said reinforcing mesh is secured between said first plate washers and said second plate washers.

[0017] Typically, said mount of said apparatus is mounted on a boom arm of a drilling rig.

[0018] In one example, said reinforcing mesh is formed of a flexible plastics material. The reinforcing mesh may be stretched whilst mounting on said frame face.

[0019] In another example, said reinforcing mesh is in the form of a chain link mesh.

Alternatively, said reinforcing mesh may be in the form of a welded steel mesh.

Brief Description of Drawings

[0020] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings wherein:

[0021] Figure 1 is an isometric view of an apparatus for installing a reinforcing mesh; [0022] Figure 2 is an isometric view of the apparatus of Figure 1 mounted on a boom arm;

[0023] Figure 3 is an isometric view of a reinforcing mesh mounted on the apparatus and boom arm of Figure 2;

[0024] Figures 4 and 5 are enlarged fragmentary views of the reinforcing mesh and apparatus of Figure 3;

[0025] Figures 6 to 9 are isometric views depicting successive stages of installation of a reinforcing mesh according to a first embodiment;

[0026] Figure 10 is an isometric view of an alternate form of reinforcing mesh mounted on the apparatus and boom arm of Figure 2;

[0027] Figures 1 1 and 12 are enlarged fragmentary views of the alternate reinforcing mesh and apparatus of Figure 10;

[0028] Figures 13 to 16 are isometric views depicting successive stages of installation of the reinforcing mesh according to a second embodiment; and

[0029] Figures 17 to 20 are isometric views depicting successive stages of installation of the reinforcing mesh according to a third embodiment.

Description of Embodiments

[0030] Figure I depicts an apparatus 100 for installing a reinforcing mesh to secure a rock face. The apparatus 100 comprises a support frame 1 10, a plurality of locating elements 120 and a mount 130. The support frame 110 has a plurality of frame elements, here in the form of an opposing pair of side frame elements 111, an end frame element 112 and diagonal frame elements 113 that join opposing frame corners 1 14 of the frame 1 10 and intersect in the frame centre 1 15 of the frame 110. In the particular configuration depicted, one end of the support frame 110 is left open without a frame element spanning between the opposing side frame elements 1 1 1. The support frame 1 10 may be of any suitable configuration, including with addition of an opposing end frame element or omission of one or more of the frame elements, including at the end of the support frame 1 10. [0031 ] Each of the frame elements 1 i 1, 1 12, 1 13 is in the form of an elongate tubular section, but could alternatively be in any of various forms, including angle, C-channet or flat sections. In a particular preferred form, the support frame 110 is constructed of tubular steel frame elements 1 1 1, 112, 1 13 that are welded together to form a rigid suppoit frame 1 10. The frame elements 1 1 1, 1 12, 1 13 are arranged at least substantially in a common plane so as to define an upper frame face 116 of the support frame 1 10 that is here also substantially planar. The side frame elements 111 and end frame element 112 define the periphery of the support frame 110 and will be sized to suit the specific size of the sheet of reinforcing mesh to be installed. The support frame 1 10 will typically have a length (defined by the side frame elements 1 11) of the order of 1.5 to 4.0 m and a width (defined by the length of the end frame element 112) of the order of 1.5 m to 4.0 m In the embodiment depicted the support frame 110 has a length of 3.0 m and width of 2.4 m for installing a standard reinforcing mesh sheet size of 3.0 m by 2.4 m.

[0032] The locating elements 120 are each mounted on the suppoit frame 110 and project from the upper frame face 1 16. It is preferred that the locating elements 120 are spaced about the periphery of the support frame 1 10. hi the arrangement depicted, locating elements 120 are located adjacent each of the frame corners 114 and spaced along each of the side frame elements 1 1 1 and end frame element 1 12. Further locating elements 120 are also located on the diagonal frame elements 1 13. In other configurations, the locating elements 120 may be located adjacent the frame corners 114 only, or elsewhere on the upper frame face 116. The locating elements 120 are configured to extend through apertures of the reinforcing mesh to be installed, as will be further discussed below.

[0033] In die arrangement depicted, the locating elements 120 are in the form of pins which may suitably be welded to each of the frame elements 111 , 112, 113. The locating elements 120 should preferably have a height at least equal to the thickness of the reinforcing mesh so as to best retain the reinforcing mesh on the support frame 1 10. In applications where the apparatus 100 is to be used to install a reinforcing mesh on a rock face defining a wall of a mine, tunnel or other ground excavation, as opposed to a roof, it may be appropriate to provide locating elements 120 of an increased length. Lengths up to 200 or 300 mm for at least some of the locating elements 120, particularly those adjacent the frame corners 1 14, may be suitable. Such increased lengths of the locating elements 120 will assist in preventing the reinforcing mesh from falling from the support frame 1 10 whilst maneuvering the apparatus 100 into position against the rock face. In the case of such elongate locating elements 120, it is envisaged that they may be removable, being removably mounted in sockets provided through the upper frame face 1 16. The elongate locating elements 120 could then be removed prior to loading the reinforcing mesh on to the upper frame face 116 and then replaced once the reinforcing mesh is in position.

[0034] The mount 130 is fixed to the lower frame face 117 of the frame 1 10 and in the embodiment depicted is welded to the diagonal frame elements 113 at the frame centre 115. The mount 130 is configured to be mounted to a support arm, such as a boom arm 150 of a drilling rig, as is particularly depicted in Figure 2. The mount 130 is typically in the form of a rigid flange or base plate configured to be mechanically secured to the boom arm 150. The mount 150 may attach directly to an articulated joint of the boom arm 150, or attach elsewhere to the frame of the boom arm 150 as desired. The boom arm 150 is able to manouevre and pivot through multiple axes under the control of the drilling rig operator. With the apparatus 100 rigidly connected to the articulated boom arm 150 via the mount 130, the operator will be able to move the apparatus 100 through various heights and angles to position the frame i 10 and reinforcing mesh 200 adjacent the roof or wall of an underground tunnel.

[0035] Figure 3 to 5 depict the apparatus 100 and drilling arm 150 with a sheet of reinforcing mesh 200 mounted on the upper frame face 1 16. The sheet of reinforcing mesh 200 depicted is formed of a flexible plastics material, such as polyester, polyethylene or polypropylene. The sheet of reinforcing mesh 200 may typically be in the general form of what is known as a 'Oeogrid", known for use in reinforcing of soils in various applications, and stabilization in long wall mine change over applications. The sheet of reinforcing mesh 200 is formed of an array of longitudinally extending mesh elements 201 and an array of laterally extending mesh elements 202 that together define a network of apertures 203 extending through the reinforcing mesh 200. Being formed of flexible plastics material, the reinforcing mesh 200 is not self-supporting and would thus be difficult to manually hold in place against a rock face during installation. As best seen in Figures 4 and 5, the reinforcing mesh 200 is mounted on the upper frame face 116 with each of the locating elements 120 extending through an aperture 203 of the reinforcing mesh 200. To assist in retaining the reinforcing mesh 200 on the support frame 1 10, the reinforcing mesh 200 may be stretched as it is mounted onto the support frame 110. This results in the locating elements 120 forceably engaging the adjacent mesh elements 201, 202, assisting in retaining the reinforcing mesh 200 on the support frame 110. [0036] Installation of the reinforcing mesh 200, according to a first embodiment, utilizing the apparatus 100 will now be described with reference to Figures 6 to 9. The apparatus 100 is mounted onto a boom arm ISO of a drilling rig by way of the mount 130. With the boom arm 150 lowered to an accessible position, the reinforcing mesh 200 is mounted onto the upper frame face 1 16 as described above, with locating elements 120 extending through apertures 203 of the reinforcing mesh 200. Leaving one or both ends of the support frame 110 open, without an end frame element 112, enables an installer to move within the support frame 110 when mounting the reinforcing mesh 201 if desired.

[0037] Referring to Figure 6, the boom arm 150 is raised toward the rock face 1 defining, in the arrangement depicted, the roof of a mine. Drilling rigs are typically configured with boom arms 150 mounted on the ends of extendable boons that provide for multi-axis degrees of freedom, thereby enabling manipulation of the apparatus 100 to position the reinforcing mesh 200 and upper .frame face 116 against the rock face I . In configurations where one or more of the locating elements 120 is of a length significantly exceeding the thickness of the reinforcing mesh 200, the apparatus 100 will be maneuvered such that the locating elements 120 engage the rock face 1 , leaving the reinforcing mesh 200 spaced from the rock face 1.

[0038] Next referring to Figure 7, boreholes are drilled, through apertures 203 of the reinforcing mesh 200, into the rock face 1 and a rock bolt 300 is then installed, again through an aperture 203 of the reinforcing mesh 200, into each of the boreholes using a further boom arm 170 of the drilling rig. Each of the rock bolts 300 is installed into each of the boreholes in the usual manner, with a plate washer 301 mounted on each rock bolt 300 immediately leading the rock bolt head 302. The rock bolt 300 may be of any suitable form, including in the form of a cable bolt or rigid steel bar form of rock bolt, or fiberglass rock bolt or friction bolt. The plate washer 301 sandwiches the reinforcing mesh 200 between the plate washer 301 and the rock face 1 , thereby securing the reinforcing mesh 200 against the rock face 1. In configurations where one or more of the locating members 120 is of a length greater than the thickness of the reinforcing mesh 200, such that the reinforcing mesh 200 is initially spaced from the rock face 1 , the plate washer 301 lifts the reinforcing mesh 200 from the upper frame face 1 16 into engagement with the rock face 1.

[0039] Next referring to Figure 8, the apparatus 100 and boom arm 150 are then withdrawn from the installed reinforcing mesh 200 and rock face 1, leaving the reinforcing mesh 200 secured against the rock face I. The process is then repeated to install further sheets of reinforcing mesh 200 along the roof and/or walls of the mine as required.

[0040] Figures 10 to 12 depict the apparatus 100 and boom arm 150 described above with a sheet of an alternate reinforcing mesh 250 mounted on the upper frame face 1 16. The sheet of reinforcing mesh 250 is in the form of a steel chain link mesh formed of interlinked or woven wire elements 25.1 that are bent into a zigzag pattern. The wire elements 251 are woven to define a network of diamond shaped apertures 253, through which the locating elements 120 extend to mount the reinforcing mesh 250 onto the upper frame face 1 16 of the frame 1 10 and through which the rock bolts 300 are installed. It is further envisaged that the apparatus 100 may be used in conjunction with rigid welded steel forms of reinforcing mesh.

[0041] Figures 13 to 16 depict installation of the reinforcing mesh 200 according to a second embodiment. In this embodiment of the method, the boreholes are drilled into the rock face 1 and the rock bolts 300 installed into each of the boreholes prior to positioning the reinforcing mesh 200 against the rock face I . Following installation of the rock bolts 300 into the boreholes, the reinforcing mesh 200, mounted on the apparatus 100 in the manner described above, is raised toward the rock face I by the boom arm 150. The reinforcing mesh 200 is raised toward the rock face 1 such that the tails of each of the rock bolts 300 extend through apertures 203 of the reinforcing mesh 200. as depicted in Figure 14. The plate washers 301 and rock bolt heads 302 are then mounted on each rock bolt 300 in the usual manner, thereby securing the reinforcing mesh 200 against the rock face 1 , between the plate washers 301 and the rock face 1. The apparatus 100 and boom arm 150 are then withdrawn, leaving the reinforcing mesh 200 secured against the rock face 1 as shown in Figure 16.

[0042] Figures 17 to 20 depict installation of the reinforcing mesh 200 according to a third embodiment. In this embodiment, the boreholes are again drilled into the rock face 1 and the rock bolts 300 installed prior to positioning of the reinforcing mesh 200. Prior to positioning of the reinforcing mesh 200, a first plate washer 301 and rock bolt head 302 is mounted on the tail of each rock bolt 300 in a known manner. As shown in Figure 17, the reinforcing mesh 200, mounted on the apparatus 100, is then raised toward the rock face 1 by the boom arm 150. The reinforcing mesh 200 is positioned with the tails of the rock bolts 300 that project beyond the rock bolt heads 302 passed through the apertures 203 of the reinforcing mesh 200. In this regard, the rock bolts 300 are installed so as to leave a greater length of tail protruding from the rock face I such that a sufficient length of the rock bolt 300 protrudes beyond the rock bolt head 302. In this embodiment, the reinforcing mesh 200 is thus spaced from the rock face 1 by the thickness of the first plate washers 301 and rock bolt heads 302. Referring next to Figure 19, the second plate washers 303 are mounted on the exposed tails of the rock bolts 300 in a known manner to secure the reinforcing mesh 200 between the first plate washer 30 l/rock bolt head 302 and the second plate washers 303. Following securing of the reinforcing mesh 200, the apparatus 100 and boom arm 150 are withdrawn, leaving die reinforcing mesh 200 secured against the rock face 1.

[0043] A person skilled in the ait will appreciate various other modifications and alterations may be made to the apparatus and method described above to suit different applications. In relation to the installation method, it is envisaged, for example, that the boreholes may be drilled before locating the reinforcing mesh and apparatus against the rock face. In relation to the apparatus, it is also envisaged that the locating elements 120, or at least locating elements 120 located adjacent the frame corners 1 14, may be provided with a clamp and release mechanism which prevents the reinforcing mesh 200 from falling off the frame 110 whilst being

maneuvered into position adjacent the rock face 1. The locating elements 120 would be in a first release position for receipt of the reinforcing mesh, following which the locating elements would be moved into a second clamping position captively retaining the reinforcing mesh 200 against the upper frame face 116. The locating elements 120 could then be returned to the first release position following securing of the reinforcing mesh 200 to the rock face 1 with the rock bolts 300, before withdrawing the support frame 1 10 from the reinforcing mesh 200. The clamp and release mechanism could be in the form of a pneumatically or hydraulically actuated clamp arm or an over centre sprung cam (or other spring mechanism) which could be manually set, and then automatically released when the support frame 1 10 is withdrawn from the secured reinforcing mesh 200. It is further envisaged that a clamping mechanism separate to the locating elements 120 might be utilized.