FIELD

[0001] The disclosure relates to assemblies for supporting a mine opening, and methods of installation thereof. Specifically, the disclosure relates to mine support assemblies that include a reinforcing element and a rockbolt.

BACKGROUND

[0002] U.S. Patent Application Publication No. 2012/0014756 (Cai and Champaigne) purports to disclose a mine roof support assembly for anchoring in a bore hole by means of a resin, or cementitious grout. The mine roof support assembly includes an elongated reinforcing tendon which extends from a proximal end portion to a distal end portion. A slip sheath formed from a heat shrunk plastic is secured by heat shrinkage radially about the tendon. The sheath is mechanically coupled to the tendon so as to allow the desired axial sliding of the tendon relative to the sheath on the application of predetermined forces which are sufficient to affect any desired yielding movement of the tendon in the bore hole. An anti-bonding agent or coating and/or anticorrosive may be interposed between the sheath and the tendon, whereby the sheath substantially encapsulates and limits the admixing of the interposed antibonding agent/anti-corrosive coating with the resin.

SUMMARY

[0003] The following summary is intended to introduce the reader to various aspects of the teaching herein, but not to define any invention.

[0004] According to one aspect, a mine support assembly for use in a bore hole of a rock comprises a reinforcing member receivable in the bore hole for reinforcing the rock. The reinforcing member extends along a longitudinal reinforcing member axis and comprises an axially extending outer wall defining a lumen. The mine support assembly further comprises a rockbolt extending along a rockbolt axis and comprising a rockbolt distal section, a rockbolt proximal section, and a rockbolt midsection disposed therebetween. A portion of the rockbolt midsection is received in the lumen, and the midsection is axially slidable within the lumen.

[0005] In some examples the reinforcing member may be one of a steel member, a fiberglass member, and a carbonfiber member.

[0006] In some examples, the outer wall may have a wall thickness of between 2 mm and 12 mm, more particularly between 5 mm and 10 mm.

[0007] In some examples, the reinforcing member may have a diameter of between 17 mm and 47 mm, more particularly between 20 mm and 35 mm.

[0008] In some examples, the rockbolt may be a yielding rockbolt. The rockbolt distal section may comprise a yielding mechanism. The yielding rockbolt may be a conebolt.

[0009] In some examples, the rockbolt may be an end anchored rockbolt. The rockbolt distal section may comprise an anchoring mechanism.

[0010] In some examples, the rockbolt midsection may have a midsection length, and the reinforcing member may have a member length, and the midsection length may be between 100 mm and 1500 mm greater than the member length, more particularly between 300 mm and 900 mm greater than the member length.

[0011] In some examples, the rockbolt proximal section may be threaded.

[0012] In some examples, the mine support assembly may further comprise a plate mountable to the rockbolt proximal section and positionable adjacent a rock face of the rock. The mine support assembly may further comprise a nut threadable onto the rockbolt proximal section.

[0013] In some examples, the outer wall may comprise an inner surface and a radially opposed outer surface, and the inner surface may be generally smooth. The outer surface may be generally rough. [0014] According to another aspect, a mine support assembly is installed in a bore hole of a rock having a rock face. The assembly comprises a reinforcing member for reinforcing the rock. The reinforcing member is received in the bore hole and anchored to the bore hole by grout. The reinforcing member extends along a longitudinal reinforcing member axis between a member distal end and member proximal end, and comprises an axially extending outer wall defining a lumen. The assembly further comprises a rockbolt extending along a rockbolt axis and partially received within the lumen. The rockbolt comprises a rockbolt distal section extending proud of the member distal end and embedded in the grout, a threaded rockbolt proximal section extending proud of the member proximal section and proud of the rock face, and a rockbolt midsection disposed between the member distal section and member proximal section. A portion of the rockbolt midsection is received in the lumen, and the rockbolt midsection is axially slidable within the lumen.

[0015] In some examples, the rockbolt may be a yielding rockbolt. The rockbolt distal section may comprise a yielding mechanism. The yielding rockbolt may be a conebolt.

[0016] In some examples, the rockbolt may be an end anchored rockbolt. The rockbolt distal section may comprise an anchoring mechanism.

[0017] In some examples, the assembly may further comprise a plate mounted to the rockbolt proximal section and positioned adjacent the rock face, and a nut threaded onto the rockbolt proximal section proximate the plate.

[0018] In some examples, the reinforcing member may be one of a steel member, a fiberglass member, and a carbonfiber member.

[0019] In some examples, the outer wall may have a wall thickness of between 2 mm and 12 mm, more particularly between 5 mm and 10 mm.

[0020] In some examples, the reinforcing member may have a diameter of between 17 mm and 47 mm, more particularly between 20 mm and 35 mm. [0021] In some examples the rockbolt midsection may have a midsection length, the reinforcing member may have a member length, and the midsection length may be between 100 mm and 1500 mm greater than the member length, more particularly between 300 mm and 900 mm greater than the midsection length.

[0022] In some examples, the outer wall may comprise an inner surface and a radially opposed outer surface, and the inner surface may be generally smooth. The outer surface may be generally rough.

[0023] According to another aspect, method of installing mine support assembly in a bore hole of a rock comprises: a) inserting an assembly comprising a reinforcing member and a rockbolt into a bore hole; b) and anchoring the reinforcing member in the bore hole with grout.

[0024] In some examples, step b) may comprise anchoring the reinforcing member such that the reinforcing member reinforces the rock, and the rockbolt is axially slidably within a lumen of the reinforcing member.

[0025] In some examples, step a) may comprise simultaneously inserting the reinforcing member and the rockbolt into the bore hole.

[0026] In some examples, the method may further comprise inserting the rockbolt into the lumen of the reinforcing pipe prior to step a).

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the present specification and are not intended to limit the scope of what is taught in any way. In the drawings:

[0028] Figure 1 is a perspective view of an example mine support assembly;

[0029] Figure 2 is a cross-sectional view taken along line 2-2 in Figure 1 ; [0030] Figure 3 is an enlarged view of the region shown in box Figure 2;

[0031] Figure 4 is a cross-sectional view taken along line 4-4 in Figure 1 ;

[0032] Figure 5 is a schematic view showing a bore hole in a rock;

[0033] Figure 6 is a cross-sectional view showing the mine support assembly of Figure 1 installed in the bore hole of Figure 5; and

[0034] Figure 7 is a cross-section view showing the mine support assembly and bore hole of Figure 5 after the rockbolt of the mine support assembly has slid axially.

DETAILED DESCRIPTION

[0035] Various apparatuses or processes will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover processes or apparatuses that differ from those described below. The claimed inventions are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below. Any invention disclosed in an apparatus or process described below and for which an exclusive right is not granted by issuance of this patent application may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document.

[0036] The disclosure relates to a mine support assembly. The mine support assembly may be used, for example, in a mine roof, retaining wall, and/or rock wall. In some examples, the mine support assembly may be used in highly stressed, burst-prone grounds, or squeezing grounds. The mine support assembly may be installed in a bore hole of a rock, for example may be anchored in a bore hole by grout or other cementitious material. The mine support assembly may serve to both reinforce the rock, and to dissipate energy under static and/or dynamic loading. Particularly, as will be described in further detail below, the mine support assembly may generally include a reinforcing member, and a rockbolt, which are assembled together, either in a factory or on site. The reinforcing member may generally serve to reinforce and strengthen the rock, and the rockbolt may generally dissipate energy under static and/or dynamic loading. The reinforcing member and rockbolt may be assembled together and installed together in a single bore hole. This may generally allow for simplified installation. Furthermore, in some examples, this may allow for the drilling of minimal bore holes in a rock, and the use of minimal grout.

[0037] Referring now to Figure 1 , an example of a mine support assembly 100 is shown. The mine support assembly 100 generally includes a reinforcing member 102, and a rockbolt 104. As mentioned above, the reinforcing member 102 is receivable in and anchored to a bore hole of a rock, and may serve to reinforce the rock and to strengthen the rock. The rockbolt 104 is partially received within the reinforcing member 102, and may, in some examples, be connected to a retaining element (not shown), such as wire mesh, shotcrete, or a strap, in order to hold the retaining element to the rock. The rockbolt 104 is slidable within the reinforcing member 102, so that it may slide under static and/or dynamic loading to dissipate energy. For example, the sliding of the rockbolt may involve axial displacement of the rockbolt within the reinforcing member (e.g. in the case of a yielding rockbolt), or stretching of the rockbolt within the reinforcing member (e.g. in the case of an end anchored rockbolt).

[0038] Referring to Figures 2 to 4, in the example shown, the reinforcing member 102 is generally in the form of a pipe. The reinforcing member 102 extends along a longitudinal reinforcing member axis 106 between a member distal end 107 and a member proximal end 109, and includes an axially extending outer wall 108 defining a lumen. The outer wall 108 has an inner surface 110, and an outer surface 112. [0039] The reinforcing member 102 may be made of any material suitable for reinforcing a rock. For example, the reinforcing member may be a steel member, a fiberglass member, or carbonfiber member. In examples where the reinforcing member is a steel member, the steel may be commonly used mild steel or high strength steel.

[0040] In some examples, the inner surface 1 10 of the outer wall 108 may be generally smooth, so that the rockbolt may slide within the lumen, as will be described in further detail below. The outer surface 1 12 may be generally deformed or rough, so that the reinforcing member 102 can be firmly bonded to the bore hole by grout, as will be described in further detail below.

[0041] The dimensions of the reinforcing member 102 may vary. In some examples, the reinforcing member 102 may have a member length 1 14 of between about 1000 mm and 2500 mm, more particularly between about 1250 mm and 1750 mm. In one particular example, the reinforcing member 102 may have a member length 114 of about 1500 mm.

[0042] In some examples, the reinforcing member 102 may have a diameter 1 16 of between about 17 mm and about 47 mm, more particularly between about 20 mm and about 35 mm. In one particular example, the reinforcing member 102 may have a diameter 1 16 of about 31 mm.

[0043] In some examples, the outer wall 108 of the reinforcing member

102 may have a wall thickness 118 of between about 2 mm and about 12 mm, more particularly between about 5 mm and about 10 mm. In one particular example, the outer wall 108 may have a wall thickness 1 18 of about 5.5 mm.

[0044] Referring still to Figures 2 to 4, the rockbolt 104 is partially received within the lumen of the reinforcing member 102. The rockbolt 104 extends along a rockbolt axis 120 and includes a rockbolt distal section 122, a rockbolt proximal section 124, and a rockbolt midsection 126 therebetween.

[0045] In the example shown, a portion 128 of the rockbolt midsection 126 is received in the lumen of the reinforcing member 102, and the rockbolt midsection 126 is axially slidable within the lumen of the reinforcing member 102. For example, the sliding of the rockbolt midsection may involve axial displacement of the rockbolt midsection within the reinforcing member (e.g. in the case of a yielding rockbolt), or stretching of the rockbolt misection within the reinforcing member (e.g. in the case of an end anchored rockbolt).

[0046] The rockbolt distal section 122 extends proud of (i.e. beyond) the reinforcing member distal end 107, and in use may be embedded in the grout. The rockbolt proximal section 124 extends proud of the reinforcing member proximal end 109, and in use, may extend proud of the rock face 130 (shown in Figures 6 and 7).

[0047] The rockbolt 104 may be, for example, a yielding rockbolt or an end-anchored rockbolt, which are known in the art and are not described in detail herein. In the example shown, the rockbolt 104 is a yielding rockbolt of the type commercially known as a "modified conebolt", and includes a yielding mechanism 132 at the rockbolt distal section 122. The yielding mechanism 132 includes a conical member that, in use, is embedded in the grout.

[0048] In the example shown, in use, under dynamic and/or static loading, the rockbolt 104 may slide axiaily. Particularly, the rockbolt midsection 126 may slide axiaily within the lumen of the reinforcing member 102 so that the rockbolt 104t is axiaily displaced, and the yielding mechanism 132 may be drawn through the grout. As the yielding mechanism 132 is drawn through the grout, energy is absorbed and dissipated from the surrounding rock.

[0049] In alternative examples, the rockbolt may be another type of rockbolt. For example, the rockbolt may be an end-achored rockbolt, which may include an anchoring mechanism at the distal section. The anchoring mechanism may be securely anchored in the grout. The end-anchored rockbolt may slide within the lumen by axial stretching of the rockbolt. Particularly, in an end-anchored rockbolt, as the load becomes greater than the yielding load of the steel, the rockbolt can stretch and accommodate large wall deformation, thus aborbing and dissipating energy. [0050] In the example shown, the rockbolt distal section 122 further includes a projection 133 to facilitate mixing of resin, as will be described below.

[0051] The dimensions of the rockbolt 104 may vary. In some examples, the rockbolt may have a rockbolt length 134 of between about 1000 mm and about 6000 mm, more particularly between about 1500 mm and about 3000 mm. In one particular example the rockbolt may have a rockbolt length 134 of about 2400 mm.

[0052] In some examples, the rockbolt may have a rockbolt diameter 136 of between about 12 mm and about 35 mm, more particularly between about 15 mm and about 25 mm. In one particular example the rockbolt may have a rockbolt diameter 136 of about 20 mm.

[0053] In some examples, the rockbolt midsection 126 may be sized to allow for the rockbolt to slide within the lumen by between about 100 mm and 1500 mm, more particularly between about 300 mm and about 900 mm. That is, the length 138 of the midsection (also referred to as the 'midsection length') may be greater than the member length 1 4 by between about 100 mm and 1500 mm, more particularly between about 300 mm and about 900 mm.

[0054] Referring still to Figures 2 to 4, in the example shown, the mine support assembly 100 further includes an optional plate 140, and a nut 142. The plate is mountable to the rockbolt proximal section 124, and in use, is positionable adjacent the rock face 130 of the rock. The rockbolt proximal section 124 is threaded, and the nut is threadable onto the proximal section proximate the plate 0 to hold the plate against the rockface 130.

[0055] In general, the assembly 100 may be installed by inserting the reinforcing member 102 and a rockbolt 104 into a bore hole 144, and anchoring the reinforcing member 102 and rockbolt 104 in the bore hole with grout. An example series of steps for the installation will now be described with reference to Figures 5 to 7. [0056] Referring to Figure 5, a bore hole 144 may be drilled in a rock 145. Any suitable grout or grout precursor may be loaded into the bore hole 144. For example, a series of resin cartridges 147, may be inserted into the bore hole 144.

[0057] Referring to Figure 6, the mine support assembly 100 may then be inserted into the bore hole 144. The assembly 100 may be inserted in a pre-assembled configuration, with the rockbolt 104 partially received in the lumen of the reinforcing member 102. That is, the reinforcing member 102 and rockbolt 104 may be simultaneously inserted into the bore hole 144. As the assembly 100 is inserted, the projection 133 may rupture the cartridges 147, and provide preliminary resin mixing. The assembly 100 may be inserted until the plate 140 is adjacent the rock face 130. The plate 140 and nut 142 may then be mounted to the rockbolt proximal section 124.

[0058] The assembly 100 may then be rotated, for example by using a torqueing mechanism, so that the projection 133 and the rough surface of the reinforcing member 102 further mix the resin. The resin may then be permitted to set to form grout 146, in order to anchor the reinforcing member 102 to the bore hole 144.

[0059] Referring to Figure 7, after installation, if the mine support assembly 100 experiences a sufficient load, for example if a rockburst occurs, the rockbolt 104 may be axially displaced and slide axially within the lumen of the reinforcing member 102, and the yielding mechanism 132 may plow through the resin to dissipate energy associated with the rockburst. The reinforcing member 102 may continue to reinforce and strengthen the rock 145.

[0060] While the above description provides examples of one or more processes or apparatuses, it will be appreciated that other processes or apparatuses may be within the scope of the accompanying claims.