AU721817B1

AU721817B1 - Mine roof truss with cable tie member

Info

Publication number: AU721817B1
Application number: AU14991/00A
Authority: AU
Inventors: Robert Pride; John C. Stankus; Kendal L. Taylor
Original assignee: FCI Holdings Delaware Inc
Current assignee: FCI Holdings Delaware Inc
Priority date: 1999-02-10
Filing date: 2000-02-09
Publication date: 2000-07-13
Anticipated expiration: 2020-02-09
Also published as: GB2346635B; GB2346635A; ZA200000569B; GB0002816D0; CA2298210A1

Description

-1-

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant/s: Actual Inventor/s: Address for Service: Invention Title: Jennmar Corporation John C Stankus and Kendal L. Taylor and Robert Pride BALDWIN SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 'MINE ROOF TRUSS WITH CABLE TIE MEMBER' The following statement is a full description of this invention, including the best method of performing it known to me/us:- File: 27053AUP00 la MINE ROOF TRUSS. WITH CABLE TIE MEMBER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roof truss system and, more particularly, to a truss system for supporting mine roofs having a horizontal tie member formed from a length of cable.

2. Prior Art Truss-type mine roof supports are well-known in the art of supporting the roof of an underground passageway, such as a mine passageway. The basic truss system includes one or more rods extending horizontally the width of the mine passage adjacent the roof and connected at their ends to anchor bolts which extend at an angle adjacent the ribs of the passageway into the rock strata over a solid pillar.

The rods are tensioned and the vertical components of compressive forces are transmitted into the solid material over the pillars, as opposed to the unsupported rock material immediately above the passageway. In this manner, the truss system redistributes roof stresses from over the mined out passageway back onto the pillars.

In a typical installation, angled boreholes are drilled into the strata over the pillars at the rib. Anchor bolts are inserted into the drilled holes and are secured into place using mechanical expansion shell assemblies, cable bolt assemblies, or similar mine roof bolts in combination with resin. Before the bolts are inserted into the drilled holes, truss shoes or bearing blocks are positioned on the end of the bolt emerging from the borehole. After the bolts are securely anchored into the bore holes, the bearing surfaces of the truss shoes are compressed into engagement with the mine roof. Once the truss shoes are securely positioned at the mine roof adjacent to the ribs, the horizontal truss members are assembled and connected to the 'truss shoes to complete the 2 truss. The horizontal truss members are then tightened to a preselected torque to exert tension on the truss so that stresses are shifted along the horizontal truss members upwardly and outwardly into the solid rock strata over the ribs.

One difficulty in installing truss systems is the cumbersome nature of positioning truss hardware overhead to form a truss system beneath the roof of a mine passageway. Therefore, certain truss systems have been proposed to ease assembly of the truss hardware.

U.S. Patent No. 5,302,056 discloses U-shaped members or bolts which releasably engage a pair of truss brackets. Each of the U-shaped members is supported by horizontal arm members on the truss brackets. The end portions of each of the U-shaped members are received in a holder having a pair of boreholes therethrough. A pair of rods coupled together form the horizontal truss member and extend between the two holders. The rods include a tie rod threaded into one end of a coupler and a torquing rod threaded into the other end of the coupler. Each of the tie rod and the torquing rod extends through the boreholes in the respective holders and is connected thereto via a hex nut and washer.

One drawback to the disclosed system is the requirement of a multiple component horizontal truss member including a torquing rod, a tie rod, and a coupler. In order to minimize the complexity of a truss system and the variety of components required for use underground, a need remains for a truss system with less components and which is easier to install.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

SUMMARY OF THE INVENTION According to a first aspect, the present invention provides a truss system for a mine roof comprising: a first mine roof bolt and a second mine roof bolt; a first truss bracket positioned adjacent the first mine roof bolt and a second truss bracket positioned adjacent the second mine roof bolt; a first cable mount forming a first cable receiving hole and a second cable mount forming a second cable receiving hole, the first cable mount positioned adjacent the first truss bracket and the second cable mount positioned adjacent the second truss bracket; a cable having a first end and a second end, the first end passing through the first cable receiving hole in the first cable mount and the second cable end passing through the second cable receiving hole in the second cable mount; a barrel and wedge assembly positioned adjacent the first end of the cable; and a second tensioning device positioned adjacent the second cable end of the cable.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

According to a second aspect, the present invention provides a method of installing a truss system having a cable with a first end and a second end comprising the steps of: a. positioning a first truss bracket adjacent the first mine roof bolt and a second truss bracket adjacent the second mine roof bolt; b. installing a first mine roof bolt and a second mine roof bolt in a mine roof; c. positioning a first cable mount adjacent the first truss bracket and a second cable mount adjacent the second truss bracket, the first cable mount forming a first cable receiving hole and the second cable mount forming a second cable receiving hole; 3 ~3~w~iJJ

S.

d. passing the first end of the cable through the first cable receiving hole in the first cable mount and the second end of the cable through the second cable receiving hole in the second cable mount; e. Attaching a barrel and wedge assembly to the first end of the cable and a second tensioning device to the second end of the cable; and f. moving the barrel and wedge assembly in a direction toward the first cable mount.

According to another aspect, the present invention provides a truss system for a mine roof comprising: a first mine roof bolt and a second mine roof bolt; a first truss bracket forming a first support arm and a second truss bracket forming a second support arm, the first truss bracket positioned adjacent the first mine roof bolt and the second truss bracket positioned adjacent the second mine roof bolt; a first U-shaped bolt forming a first arcuate portion, a first prong, and a second prong, and a second U-shaped bolt forming a second arcuate portion, a third prong, and a fourth prong, the first arcuate portion of the first U-shaped bolt removably connected to the first support arm of the first truss bracket and the second arcuate portion of the second U-shaped bolt removably connected to the second support arm of the second truss bracket; a first holder forming a first receiving hole and a second holder forming a second receiving hole, the first holder moveably connected to the first and second prongs of the first U-shaped bolt and the second holder moveably connected to the third and fourth prongs of the second U-shaped bolt; a cable, having a first end and a second cable end, the first end passing through the first cable receiving hole in the first holder and the second cable end passing through the second cable receiving hole in the second holder; a barrel and wedge assembly moveably positioned adjacent the first end of the cable, between the first holder and the first arcuate portion of the first U-shaped bolt; and a second tensioning device positioned adjacent the second end of the cable, positioned between the second holder and the second arcuate portion of the second Ushaped bolt.

A, Lu'~ 1 In operation, sliding the barrel and wedge assembly positioned adjacent the first end of the cable in a direction toward the first cable mount and the second tensioning device toward the second cable mount induces tension in the cable, transmitting compressive forces into the solid material in the roof over the passageway.

A complete understanding of the invention will be obtained from the following description when taken in connection with the accompanying drawing figures wherein like reference characters identify like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional side elevation view of an underground passageway showing a truss system made in accordance with the present invention and extending the width of the passageway; and AI j -o 5 Fig. 2 is plan view of the truss system depicted in Fig. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions.and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting.

A truss system 10 made in accordance with the present invention is generally shown in Figs. 1 and 2. The truss system 10 is used for supporting a roof R above an underground passageway G cut in a rock formation by conventional mining methods to extract solid materials such as coal in a mining operation.

The underground passageway G is defined by oppositely positioned side walls W, W' formed by ribs or pillars P that extend between the roof R and a floor F. The portion of the rock formation above the roof R may be supported or unsupported. The truss system 10 is installed transversely across the underground passageway G adjacent the roof R to provide an uplifting force through the unsupported roof R by which the stresses in the rock formation above the roof R are shifted horizontally and redirected to the rock formation supported by the pillars P.

6 The truss system 10 is secured to the mine roof R by a first mine roof bolt 12 inserted into a first bore hole 16 and a second mine roof bolt 14 is inserted into a second bore hole 16'. The first and second bore holes 16, 16' are drilled at an angle, preferably 450, through the surface of the roof R.

The first and second mine roof bolts 12, 14 may be a conventional rock bolt, having an expansion assembly 18 anchored with resin 20, or a resin grouted cable bolt (not shown) which may be tensioned or untensioned.

The truss system 10 further includes a first truss bracket 22 and a second truss bracket 24. The first truss bracket 22 and the second truss bracket 24 each define arms, with the first truss bracket 22 forming a first arm 26 and the second truss bracket 24 forming a second arm 27. Each arm 26, 27 preferably extends outwardly from its respective truss bracket 22, 24, horizontal to the mine roof R. As shown in Fig. 2, the first and second truss brackets 22, 24 also each form openings, with the first truss bracket 22 forming opening 28 and the second truss bracket 24 forming opening 28'. The opening 28 formed by the first truss bracket 22 receives a free end 30 of the first mine roof bolt 12 and the opening formed by the second truss bracket receives a free end 30' of the second mine roof bolt 14. The free ends 30, 30' of the first and second mine roof bolts 12, 14, respectively, are prevented from passing through the openings 28, 28' in the truss brackets 22, 24 by boltheads 32 positioned adjacent the free ends 30, of the mine roof bolts 12, 14. For rock bolts, the bolthead 32 may be an integrally forged component.

For cable bolts, the bolthead 32 may be a barrel and wedge assembly and may further include a drivehead fixed to the end of the cable bolt in accordance with 7 the cable bolt disclosed in U.S. Patent No. 5,829,922, incorporated herein by reference. One of the mine roof bolts 12, 14, such as the first mine roof bolt shown in Fig. i, may also include a bolthead 32 that is enlarged.

Referring to Fig. i, the truss system further includes a first cable mount 34 and a second cable mount 36. The first and second cable mounts 34, 36 permit a cable to be connected to the first and second truss brackets 22, 24, and may be formed directly from the first and second arms 26, 27 of the first and second truss brackets 22, 24. However, the preferred embodiment of the first cable mount 34, shown in detail in Fig. 2, includes a first U-shaped bolt 38 having a first arcuate portion 40, a first prong 42, and a second prong 44. The second cable mount 36 also preferably includes a second U-shaped bolt 46 having a second arcuate portion 40', a third prong 48, and a fourth prong 50. The first and second prongs 42, 44 of the first U-shaped bolt 38 and the third and fourth prongs 48, 50 of the second U-shaped bolt 46 may be threaded and are positioned in a spaced apart parallel relationship. The first and second prongs 42, 44 of the first U-shaped bolt 38 and the third and fourth prongs 48, 50 of the second U-shaped bolt 46 are integrally connected to each other via their respective arcuate portions 40, The preferred embodiment of the first cable mount 34 further includes a first holder 52 positioned adjacent the first and second prongs 42, 44 of the first U-shaped bolt 38 and a second holder 54 is positioned adjacent the third and fourth prongs 48, of the second U-shaped bolt 46. The first holder 52 preferably forms a pair of bores 56 for receiving the first and second prongs 42, 44 of the first U-shaped bolt 38 and the second holder 54 forms a pair of bores 8 56' for receiving the third and fourth prongs 48, of the second U-shaped bolt 46.

A stop 58 is provided on each of the first, second, third, and fourth prongs 42, 44, 48, 50 to prevent the first and second holders 52, 54 from separating from their respective U-shaped bolts 38, 46. The stops 58 can be caps, fasteners, or forged ends, and are preferably integrally forged with the first, second, third, and fourth prongs 42, 44, 48, 50. Moreover, the first and second holders 52, 54 can be attached to their U-shaped bolts 38, 46 in other ways, such as by welds or an integral connection.

The first holder 52 further defines a first cable receiving bore 60 and the second holder 54 further defines a second cable receiving bore 62. The first cable receiving bore 60 is sized to receive a first end 64 of a cable 66 therethrough. The second cable receiving bore 62 is sized to receive a second end 68 of the cable 66 therethrough. The cable 66 is preferably a multistrand uncoated steel or galvanized Grade 270 cable (minimum strength of 270,000 psi) having a diameter of 0.6 inch or 0.7 inch. Other Scables, sizes and grades can likewise be used depending on the application.

With continuing reference to Fig. 2, the cable 66 extends between the first and second holders 52, 54 when the first end 64 of the cable 66 is received by the first holder 52 and the second end 68 of the cable 66 is received by the second holder 54.

A barrel and wedge assembly 70 of the type common in the art is positioned adjacent the first end 64 of the cable 66, between the first holder 52 and the arcuate portion 40 of the first U-shaped bolt 38, as shown in detail in Fig. 2. A second tensioning device 72 is positioned adjacent the second end 68 of the cable 66.

The second tensioning device 72 is also preferably a barrel and wedge assembly 70, as shown in Fig. 1, but -9may also be a fixed nut 74 or some other suitable device, as shown in Fig. 2.

Referring again to Fig. 1, the truss system is preferably installed as follows. A pair of bore holes 16, 16' are drilled into the mine roof R at angles of approximately 450. The spacing of the bore holes 16, 16' is determined by the size of the passageway G, the mining conditions, and/or a particular roof control plan. The bore holes 16, 16' are preferably about one inch longer than the length of the first and second mine roof bolts 12, 14 to be inserted therein. Resin 20 is inserted into a blind end of the bore holes 16, 16' The next'step is positioning the first truss bracket 22 adjacent the first mine roof bolt 12 and the second truss bracket 24 adjacent the second mine roof bolt 14. To accomplish this, the mine roof bolts 12, 14 are inserted through their respective truss brackets 22, 24 and installed in a conventional manner.

After the truss brackets 22, 24 are positioned, the first cable mount 34 is positioned adjacent the first truss bracket 22 and the second cable mount 36 is positioned adjacent the second truss bracket 24. If the preferred first and second cable mounts 34, 36 have first and second U-shaped bolts 38, 46 and first and second holders 52, 54, the first Ushaped bolt 38 is suspended from the first arm 26 of the first truss bracket 22 and the second U-shaped bolt 46 is suspended from the second arm 27 of the second truss bracket 24.

Next, the first end 64 of the cable 66 is inserted through the first cable receiving bore 60 in the first holder 52 and the second end 68 of the cable 66 is inserted through the second cable receiving bore 62 in the second holder 54. A barrel and wedge 10 assembly 70 is slipped over the first end 64 of the cable 66. A second tensioning device 72, such as a barrel and wedge assembly 70 or a fixed nut 74, is slipped over or connected to the second end 68 of the cable 66. Preferably, about six inches of the cable 66 protrudes beyond the barrel and wedge assembly positioned adjacent the first end 64 of the cable 66 and also six inches beyond the second tensioning device 72 positioned adjacent the second end 68 of the cable 66.

The barrel and wedge assembly 70 positioned adjacent the first end 64 of the cable 66 is urged away from the first end 64 and toward the first cable mount 34. The barrel of the barrel and wedge assembly 70 abuts the first holder 52 of the first cable mount 34. If the second tensioning device 72 is also a barrel and wedge assembly 70, the barrel and wedge assembly 70 is urged away from the second end 68 of the cable 66, in a direction toward the second cable mount 34. The cable 66 is then further tensioned using a tensioning unit such as a Cable Tensioning Unit available from Jennmar Corporation of Pittsburgh, Pennsylvania. Other conventional hydraulic tensioning devices may be used to urge the barrel and wedge assembly 70 away from the first and second ends 64, 68 of the cable 66 to induce tension in the cable 66.

In an alternative method of installation, the mine roof bolts 12, 14 and the first and second truss brackets 22, 24 are installed as described above. The first and second U-shaped bolts 38, 46, the first and second holders 52, 54, the cable 66, the barrel and wedge assembly 70, and the second tensioning device 72 are preassembled and installed as a unit by placing the first and second U-shaped bolts 38, 46 (with the first and second holders 52, 54, cable 66, barrel and wedge assembly 70, and second tensioning device 72 therebetween) onto the first and 11 second arms 26, 27 formed by the first and second truss brackets 22, 24. The cable 66 is thentensioned in a similar manner as discussed above.

The mine roof truss with cable tie member of the present invention is an improvement over the trusses of the prior art in that a cable is used as a tie member, which replaces the multiple components of the horizontal tie members of conventional trusses, namely, tie rods, torquing rods, and couplers.

Multistrand cable is inherently easier to handle underground and installation of the truss of the present invention is more easily accomplished. The present invention also allows the cable to be tensioned from one end of the cable or both ends of the cable. In addition, whereas the trusses of the prior art have been used mainly as a secondary support in roof control, the mine roof truss of the present invention may be used for primary roof control.

Having described the presently preferred embodiment of the invention, it is to be understood that it may otherwise be embodied within the scope of the appended claims.

Claims

1. A truss system for a mine roof comprising: a first mine roof bolt and a second mine roof bolt; a first truss bracket positioned adjacent the first mine roof bolt and a second truss bracket positioned adjacent the second mine roof bolt; a first cable mount forming a first cable receiving hole and a second cable mount forming a second cable receiving hole, the first cable mount positioned adjacent the first truss bracket and the second cable mount positioned adjacent the second truss bracket; a cable having a first end and a second end, the first end passing through the first cable receiving hole in the first cable mount and the second cable end passing through the second cable receiving hole in the second cable mount; a barrel and wedge assembly positioned adjacent the first end of the cable; and a second tensioning device positioned adjacent the second cable end of the cable.

2. The mine roof truss system as claimed in claim 1 wherein the first mine roof bolt includes an expansion assembly.

3. The mine roof truss system as claimed in claim 1 wherein the first cable mount includes: a first U-shaped bolt forming a first arcuate portion, a first prong, and a second prong; a first holder connected to the first prong and the second prong of the first U-shaped bolt; 13 a second U-shaped bolt forming a second arcuate portion, a third prong, and a fourth prong; a second holder connected to the third prong and fourth prong of the second U-shaped bolt; and wherein the first arcuate portion of the first U-shaped bolt is removably connected to a first support arm formed by the first truss bracket and the second arcuate portion of the second U-shaped bolt removably connected to a second support arm of the second truss bracket.

4. The mine roof truss system as claimed in claim 3 wherein a plurality of stops are each individually positioned adjacent the first prong-end and the second prong end of the first U-shaped bolt.

5. The mine roof truss system as claimed in claim 1 wherein the second tensioning device is a barrel and wedge assembly.

6. A method of installing a truss system having a cable with a first end and a second end comprising the steps of: a. positioning a first truss bracket adjacent the first mine roof bolt and a second truss bracket adjacent the second mine roof bolt; b. installing a first mine roof bolt and a second mine roof bolt in a mine roof; c. positioning a first cable mount adjacent the first truss bracket and a second cable mount adjacent the second truss bracket, the first cable mount forming a first cable receiving hole and the second cable mount forming a second cable receiving hole; d. passing the first end of the cable through the first cable receiving hole in the first cable mount and the second end of the cable through 14 the second cable receiving hole in the second cable mount; e. attaching a barrel and wedge assembly to the first end of the cable and a second tensioning device to the second end of the cable; and f. moving the barrel and wedge assembly in a direction toward the first cable mount.

7. The method of installing a truss system as claimed in claim 6 further comprising the step of moving the second tensioning device in a direction toward the second cable mount.

8. The method of installing a truss system as claimed in claim 6 wherein the second tensioning device is a barrel and wedge assembly.

9. The method of installing a truss system as claimed in claim 6 wherein the first cable mount includes: a first U-shaped bolt forming a first arcuate portion, a first prong, and a second prong; a first holder connected to the first prong and the second prong of the first U-shaped bolt; a second U-shaped bolt forming a second arcuate portion, a third prong, and a fourth prong; and a second holder connected to the third prong and fourth prong of the second U-shaped bolt; wherein the first arcuate portion of the first U-shaped bolt is removably connected to a first support arm formed by the first truss bracket and the second arcuate portion of the second U-shaped bolt removably connected to a second support arm of the second truss bracket. 15 A truss system for a mine roof comprising: a first mine roof bolt and a second mine roof bolt; a first truss bracket forming a first support arm and a second truss bracket forming a second support arm, the first truss bracket positioned adjacent the first mine roof bolt and the second truss bracket positioned adjacent the second mine roof bolt; a first U-shaped bolt forming a first arcuate portion, a first prong, and a second prong, and a second U-shaped bolt forming a second arcuate portion, a third prong, and a fourth prong, the first arcuate portion of the first U-shaped bolt removably connected to the first support arm of the first truss bracket and the second arcuate portion of the second U-shaped bolt removably connected to the second support arm of the second truss bracket; a first holder forming a first receiving hole and a second holder forming a second receiving hole, the first holder moveably connected to the first and second prongs of the first U-shaped bolt and the second holder moveably connected to the third and fourth prongs of the second U-shaped bolt; a cable, having a first end and a second cable end, the first end passing through the first cable receiving hole in the first holder and the second cable end passing through the second cable receiving hole in the second holder; a barrel and wedge assembly moveably positioned adjacent the first end of the cable, between the first holder and the first arcuate portion of the first U-shaped bolt; and a second tensioning device positioned adjacent the second end of -the cable, positioned between the second holder and the second arcuate portion of the second U-shaped bolt.

16- 11. The truss system for a mine roof as claimed in claim 10 wherein the second tensioning device is a barrel and wedge assembly which is moveable with respect to the cable. 12. The truss system for a mine roof as claimed in claim 10 wherein the first mine roof bolt includes an expansion assembly anchored with resin. 13. The truss system for a mine roof as claimed in claim 10 wherein the first mine roof bolt includes an enlarged bolthead. 14. The truss system for a mine roof as claimed in claim 10 wherein the first mine roof bolt extends through an opening formed by the first truss bracket. 15. The truss system for a mine roof as claimed in claim 10 wherein the cable is made from multistrand uncoated steel. 16. The truss system for a mine roof as claimed in claim 10 wherein the cable is made from galvanized Grade 270 steel cable having a diameter of between 0.6 inches and 0.7 inches.

17. A truss system for a mine roof substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings.

18. A method of installing a truss system substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings. DATED this 9th Day of February, 2000 JENNMAR CORPORATION Attorney: JOHN DOUGLAS FORSTER Fellow Institute of Patent and Trade Mark Attornomeys of Australia of BALDWIN SHELSTON WATERS