GB2163195A - A tunnel support joint - Google Patents

Abstract

A mine arch joint and resultant arch in which-a horizontal member (10 Fig. 1,) is joined to an upright member (2 Fig. 1,) by means of a lug (22) e.g. welded to flange 16, the lug being shaped to fit snugly between flanges of the horizontal or upright member e.g. having a web, 36, the member accepting the lug abutting on the other member or part of the lug such that the stress from one member to the other is directly transferred between the members. When bolting e.g. by bolt 30 between the lug and member to which it is fitted is employed shear stress is reduced. <IMAGE>

Description

SPECIFICATION A tunnel support joint The present invention relates to mine or tunnel supports.

Typical mine roadway supports are arches formed from two leg beams which are jointed by fish plates or other jointing means to a crown beam. At intervals along the roadway in ground to be mined headways are opened out from the roadway at right angles to the roadway at suitable intervals. Roadways going through such ground have a horizontal beam extending from arch to arch at about head height, normally jointed between two parts of the legs by fish plates. When it is necessary to open up a new headway the fish plates are unbolted below the horizontal beam and the lower part of the leg is removed so that a gap is open to make a face entry in the roadway side to cut the headway.

The present arrangements for this procedure are deficient in several respects. In one arrangement using a fish plate it is necessary to have the upper and remaining portion of the leg extending down below the horizontal beam a length of half a fish plate length plus about 2.5 cm to allow for fitting, a total of about 1 8 cm to 20 cm. This extension from the horizontal beam is inconvenient as it restricts the head clearance and can cause an obstruction. An alternative arrangement uses a complicated joint in which load between the upper and lower parts of a leg is transferred at least partly by means of a bolt which can shear or under load can be difficult to remove.

An object of the present invention is to provide a joint which has a small downward projection whilst providing a good structural arrangement for load transfer.

A mine or tunnel support joint according to the invention comprises a longitudinal beam having an upper and lower flange separated by a central web, such as a 'I' beam, a bracket or lug welded to the lower flange, the bracket or lug shaped to accept a 'I' or channel sectioned arch leg member and fit between the flanges of the leg member such that the leg member's upper end abuts the beam.

The beam is preferably a metre long which is the standard distance between arches but may be between 1/2 and 2-1/2 metres and the bracket or lug is intermediate the ends of the beam. In the case of a metre length the bracket or lug may be midway along the length. The beam may be provided at each end with a suitable joining means for coupling to the next adjacent beam. Such joining means can be a simple fish plate with four holes (two for each beam with corresponding holes in the beams).

The bracket or lug may be angled or positioned on the beam in a number of different directions so that the beam can be used as part of a square headed arch with angled legs.

The connection between the lug and lower leg is preferably by means of a single bolt and nut.

Besides the use of the bracket or lug to form a square headed arch which can form a main roadway arch, it is also possible to use this for curved arches.

The joint of the invention may also comprise a lower leg having at its upper end a strengthened portion comprising a fillet or plate welded between the flanges and lying against the central web, the fillet or plate suitably perforated to accept the connecting bolt when this is used.

A great advantage in the support connections of the present invention is that the main structural members for example the main horizontal and upright members abut on one another when joined so that the abutment takes any vertical forces when assembled. In essence the joining bolts are not shear stressed by the joining so that when the uprights have to be removed for side entry unbolting is not impeded by the upper main members bearing down on the lower main members. After unbolting it is merely a matter of knocking out the upright members. Both disassembly and assembly is therefore facilitated and quick. This is important when considering use in a mining application and results in increased safety and time saving. The resulting joint has been found under trial to be highly successful and strong.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is an end side view of part of a mine arch incorporating a joint according to the invention, Figure 2 is a lateral side view of the joint shown in Fig. 1, Figure 3 is a lateral side section of the joint taken at A-A of Fig. 4, Figure 4 is an end side view of the joint of Fig. 1 seen from the same direction, and Figure 5 is a section from underneath the joint of Fig. 1 taken at B B of Fig. 4, Figure 6 is an end side view of a mine arch incorporating a joint according to a further aspect of the invention, Figure 7 is an end side view of a joining lug for the arch of Fig. 6, Figure 8 is a similar view of Fig. 7 of a modified lug, Figure 9 is an end view of the lug of Fig. 7 taken in direction A, Figure 10 is a side view of the lug of Fig. 7 Figure 11 is a pair of lugs similar to those of Fig. 7 before division, Figure 1 2 is a side view of the pair of lugs of Fig. 11, Figure 1 3 is an end view of a straight legged arch assembly according to the inven tion, Figure 14 is an end view showing the fitting of crown and upright for the arch of Fig. 13, Figure 1 5 is a similar view of Fig. 14 taken from the other side of Fig. 14, Figure 1 6 is a side view of Fig. 14 taken from B, Figure 1 7 is an end view of the joint of Fig.

14 taken from C, Figure 18 is an end view of a yet further mine arch according to a further aspect of the invention, Figure 19 is a similar view of Fig. 1 8 with a slight modification to the legs and crown member of Fig. 18, Figure 20 is an expanded view at E on Fig.

18 or 19, Figure 21 is a sectioned view from F of the joint of Fig. 20, Figure 22 is a yet further embodiment of the invention as seen from the side showing part of an upright and part of a crown member joined and using a lug substantially the same as shown in Fig. 14, Figure 23 is a view of Fig. 22 as seen from G, and Figure 24 is a view of the joint of Fig. 22 taken from H.

The arch seen in Fig. 1 comprises a lower leg portion 2 the upper part only of which is shown and an upper leg portion 4 jointed by a fish plate 6 to a crown beam 8. Between the upper and lower leg portions is a horizontal longitudinal beam 10 which forms a part of the joint generally shown in Fig. 2 and indicated generally by index 1 2.

Beam 10 is an 'I' beam having an upper flange 1 8 and lower flange 16 joined and separated by central web 20. The 'I' beam can also be a channel beam.

Welded to lower flange 1 6 is a lug or bracket 22 which extends downwards 100 mm below the lower surface of flange 1 6. The lug 22 has an angled out portion 24 to provide a broadened foot for welding at 26 to flange 1 6. An extremity 28 extending from angled out portion 24 is provided with a hole 25 38 mm in diameter to receive an M30 x 100 mm bolt 30. The line 21 where portions 24 and 28 meet is distanced from the hole 25 so that the head 31 of bolt 30 cannot turn when home in the hole. The sides 32 of lug 22 are shaped to lie snugly between the flanges 34 and 35 of 'I' beam lower leg portion 2 and to lie substantially on or with a slight gap away from central web 36 of leg portion 2. The width of the lug 22 between sides 32 is about 106 mm.The lug is suitably rebated at 27 to allow for sufficient weld fillet and still ensure close fitting of the portion 2.

The lug is cast or forged from suitable tensile steel. The lower leg portion 2 has a strengthening fillet 40 welded at 42 to the inner surfaces of the leg portion and is about 30 mm thick corresponding to the same thickness of lug extremity 28 taken parallel to the axis of the bolt hole 25. After insertion of the bolt 30 through hole 25, hole 44 in web 36 a hole 46 in fillet 40 a nut 48 is tightened onto the bolt to secure the lower leg portion 2 firmly in place with the upper surface of portion 2 abutting the flange 16. Thus the stress is carried directly between beam 10 and portion 2 of the leg. The beam 10 is suitably provided with holes 50 at each end for fishplating to an adjacent similar beam.

The upper leg portion 4 is welded to the upper flange 1 8 of the beam 10. However, the joint itself can be used for square headed supports where the upper leg portion is not necessary.

Figures 6 to 10 show the use of a lug 60 (with modified lug 60' shown in Fig. 8) similar to that at 22 but which is welded to the horizontal member, now a crown member 62, to receive in abutting relation arched legs 64 or straight legs 64'. The sole 66 of the lug can be cut at any convenient angle between say 60 through 90 to 120 by the arrangement of forging the lugs as pairs 67 seen in Figures 11 and 1 2. The sole angle is chosen and the pairs divided along line 68.

Alternatively the lug can be forged or cast singly with the sole formed at the desired angle. The sole can be formed with an indentation as at 67 to reduce the amount of metal used.

It will be seen in the as assembled Figure 1 3 to 1 6 that the uprights or legs 64' seat at the flanged upper ends 69 on abutment surfaces 70. The bolts 72 are inserted into a recess 74 (or 74') (see Figs. 7 and 8) in a similar way as described in the arrangement of Figures 1 to 5 through the upright or leg 64 (or 64') and fillet 76 (or 76') and a nut 78 placed on the bolt and tightened up. The fillet formed as at 76' saves metal. In Fig. 1 5 two notches, preferably semicircular, are formed at 77 on the top edge and at 79 on the bottom edge to provide a controlled mode of failure.

This reduces shear stress on the bolt when the arch is under stress and being deformed. The lug of Figure 8 has a step 80 in recess 74 to hold the bolt head from rotating whereas this is achieved in the Fig. 7 lug by sides 82 of recess 74.

The arrangement shown in Figures 1 8 to 21 shows an abutting joint where the junction between crown and legs is linear rather than angled. In this arrangement a lug 100 is welded to leg member 102 (or 102 ) and a lug 103 is welded to crown member 104 (or 104 ) along weld lines 106 and 108 respectively. To assemble the crown and legs these are abutted so flanges 110 and 11 2 abut at 11 4. Bolts 11 6 are then passed through the lugs and nuts 11 8 screwed home to tighten the assembly. The arrangement is simple to assemble and the end abutment of main members 102 and 104 ensures the shear stress is substantially removed from the bolts, thus allowing easy disassembly.

The arrangement shown in Figures 22 to 24 is similar to that described in Figs. 1 to 1 7 but turned through 90" so that lug 1 20 is welded to leg 1 22 and fits into crown 1 24.

Claims (14)

1. A mine or tunnel support joint comprising a longitudinal beam having an upper and lower flange separated by a central web, such as 'I' beam, a bracket or lug welded to the one flange, the bracket or lug shaped to accept a 'I' or channel sectioned arch leg member and fit between the flanges of the leg member such that the leg member's upper end abuts the beam.

2. A joint as claimed in Claim 1 wherein the beam forms a crown member of the arch.

3. A joint as claimed in Claim 1 or 2 wherein each lug is formed as one of a divided pair.

4. A joint as claimed in any one of Claims 1 to 3 wherein a fillet is welded to the end of the leg member and a hole is provided through the leg member and fillet, the lug having a similar bold provided in it so that a bolt may be passed through the lug, leg member and fillet to secure the leg to the beam.

5. A joint as claimed in any one of Claims 1 to 5 wherein each lug has an abutment adapted to receive a leg member.

6. A joint as claimed in any one of Claims 1 to 5 wherein the lug is welded to the horizontal member.

7. A joint as claimed in any one of Claims 1 to 4 where the lug is welded to the leg member and is provided with an abutment adpated to receive a crown member.

8. A joint as claimed in any one of Claims 1 to 7 wherein the lug is recessed to prevent from turning a nut or bolt head for a bolt passing through the lug to secure the beam and leg together.

9. A joint as claimed in Claim 4 wherein the fillet is notched at one or both ends.

10. A joint as claimed in any one of Claims 1 to 9 wherein the sole of the lug is indented.

11. A mine arch having the joint as claimed in any one of Claims 1 to 10.

12. A mine or tunnel arch comprising a crown member and two legs or channel or 'I' section, a lug welded to each leg between its flanges and extending longitudinally beyond the end of the leg, the lug welded at each end of the crown member and extending longitudinally beyond the ends of the crown member, each lug having a pair of holes formed through it, and each leg and the crown member having a hole through its central web so that each leg may be bolted to the crown member by means of a pair of bolts passing through the lugs and central webs of the leg and crown member, wherein the legs and crown member abut each other when bolted together.

1 3. A mine or tunnel support substantially as described with reference to Figures 1 to 5 of the accompanying drawings.

14. A mine or tunnel support substantially as described with reference to Figures 6, 7, 9 and 10 of the accompanying drawings.

1 5. A mine or tunnel support substantially as described with reference to Figures 6 and 8 of the accompanying drawings.

1 6. A mine or tunnel support substantially as described with reference to Figures 18, 20 and 21 of the accompanying drawings.

1 7. A mine or tunnel support as described with reference to Figures 19, 20 and 21 of the accompanying drawings.

1 8. A mine or tunnel support substantially as described with reference to Figures 22 to 24 of the accompanying drawings.