GB2057034A

GB2057034A - Underground roadway support

Info

Publication number: GB2057034A
Application number: GB8027624A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-08-29
Filing date: 1980-08-26
Publication date: 1981-03-25
Also published as: EP0025307A1; PL226478A1

Description

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SPECIFICATION

Underground roadway support

This invention relates to means for and a method of permanently supporting an 5 underground roadway in a mine, for example a coalmine, or an excavation in a tunnel (hereafter and in the claims referred to for convenience as "a roadway in a coal mine").

Roadways in coal mines are generally .10 supported, on a permanent basis, by RSJs placed at intervals, usually one yard apart, and lined in between by either wooden boards, concrete slabs, or wire mesh. This provides a continuous supported lined roadway.

15 The RSJs may be straight girders, but on the majority of cases they follow an arch profile and the arch section is built up from two or three sections using fish-plates and bolts.

The principal difficulty and hazard occurs when 20 the supports and lining have to be installed to support and cover newly exposed ground. Despite the use of temporary advance cover over the centre region, the workmen are at times exposed to possible roof falls, and in practice this zone of 25 operation contributes a major proportion of recorded accidents underground.

There have been constant endeavours to reduce and finally eliminate these dangers, and during the past few years some progress has been 30 made by the provision of mechanical aids to assist with the erection of the arch sections. However the lining is still done manually.

I have conceived a novel means for supporting and lining a roadway, which means involves the 35 use of prefabricated panels of, for example, steel or concrete adapted to be assembled together to form arch sections, and which can be mechanically handled from receipt at surface to underground installation.

40 In designing my roadway supporting and lining means I have been concerned to achieve certain objectives as follows:

1. Cost per yard/metre of permanent roadway lining to be as near as possible to cost of present

45 methods and materials.

2. Workmen at all times to be fully protected and never exposed to unsupported strata.

3. Resistance of supports to ground pressure to be equal or greater than those currently used.

* 50 4. Method of roadway/excavation to be unimpaired by panel erection method or installation equipment.

5. Provision for easy dismantling/withdrawal of panels in the event of replacement. 55 6. Provision for arch section to establish intimate contact with strata of excavated roadway and also for post-loading if desired.

7. Facility for formation of adjacent support packs, and for infilling, backfilling and grout 60 injection.

The roadway supporting and lining means comprises three components, namely a base panel, an arch panel and a tie device which may simply be a nut and bolt or one which is of a non-

65 screw-threaded character.

According to a first aspect of the invention I provide a roadway supporting and lining means comprising an arch section consisting of a pair of laterally-spaced base panels bridged and 70 interconnected by at least one arch panel.

Preferably there are a number of arch sections for disposition in butting relationship along the length of the roadway.

Preferably the base panels are interconnected 75 by a plurality of arch panels.

Preferably the base panels and arch panels are releasably tied together by tie devices.

Preferably the butting arch sections are releasably tied together by tie devices. 80 A second aspect of the invention is a prefabricated concrete base panel of rectangular configuration having a ground-engaging side of relatively large area, and its other three sides, each being adapted to receive at least one tie device. 85 A third aspect of the invention is a prefabricated steel base panel of rectangular construction adjustably and possibly yieldingly supported clear of the ground by a pair of legs and with its upper side and possibly its vertical sides 90 being adapted to receive at least one tie device.

A fourth aspect of the invention is an arch panel of rectangular construction and curved in one plane whereby a number assembled together in butting relationship define a semi-circular or other 95 arch form and with at least the two panel sides normal to said plane each being adapted to receive at least one tie device.

Preferably, the butting sides of adjacent panels prefabricated in concrete are serrated or rendered 100 otherwise non-smooth to facilitate matching connection and resistance to transverse forces.

Each panel (base or arch) preferably has a rib normal to and joining the butting sides or parallel with the butting sides.

105 In the case of a base panel formed of prefabricated concrete the sides and rib preferably define two open windows to permit passage of material therethrough outside the arch for pack construction or to facilitate back-filling or grouting 110 of adjacent strata. In the case of an arch panel the windows are preferably in-filled with concrete or mesh reinforcement.

With a steel arch panel, the rectangular frame is preferably formed of lateral ribs extending in the 115 direction of arching of L or H or T or channel section welded to connecting plates.

Each panel may have one or more connecting plates joining the lateral ribs intermediate the butting plates or vice versa. Alternatively the 120 butting plates or lateral ribs may be bridged by one or more sectioned ribs.

The panel surface is covered by steel wire mesh or other material such as corrugated sheeting welded, clipped or otherwise secured to the 125 rectangular frame components.

Each side of each panel (base or arch) adapted to receive at least one tie device is preferably slotted at two locations.

A fifth aspect of the present invention is a tie

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device comprising a first locking element adapted for passage through registering slots in adjacent panels into abutment with one of the panels, and a second locking element adapted to be wedged 5 between a formation on the first locking element 70 and the other panel.

The tie device may comprise a substantially L or T-shaped shear locking plate with an open-sided slot in one limb, and a wedge adapted for 10 releasable engagement in said slot. 75

In use, the locking plate is engaged through registering slots of adjacent panels until its non-slotted limb abuts the panel side and the wedge is then driven into the slot in the other plate limb 15 with the underside of the wedge butting the other 80 panel side.

Preferably the locking plate is formed of spring steel and the wedge is serrated on its plate-engaging surface. The other plate limb (non-20 slotted) has a small negative taper and this with 85 the wedge produces a high tensile constant locking force.

The tie device may comprise a headed locking pin with an enlarged base and a slotted spring 25 steel wedge. The pin preferably has flat opposed 90 surfaces for engagement by the wedge slot which has a lesser width dimension than that of the locking pin head.

The tie device may comprise a locking element 30 in the form of a U with the limbs of the U partly 95 turned outwards, and a wedge shaped locking pin.

A steel base panel is preferably constituted by two upright, lateral channel members open towards one another and connected and bridged 35 by a top plate with bridging steel wire mesh 100

welded to the inboard limb of each channel member to provide a vertical wall. The base of each channel member is vertically elongatedly slotted.

40 This steel base panel is completed by two 105

vertical channel legs also vertically elongatedly slotted which legs have bottom ground-engaging plates and rest within the channel members with an intervening resilient member between the 45 respective bases, the channel members and legs 110 being adjustably secured together by tie devices.

A sixth aspect of the invention is a steel base panel having a steel wire mesh wall adjustably and resiliently supported clear of the ground. 50 The panels may vary in overall width from 2 115 feet to 6 feet or more and their length is determined by roadway size and convenient division.

The panels may be locked together to form the 55 roadway profile by nuts and bolts or cottars or the 120 tie devices as hereinbefore defined. With the latter, to lock same in place, requires only the use of a hammer or similar while by using a lever or bar the wedge can easily be dislodged sideways. 60 It is to be noted that the tie devices can provide 125 additional shear resistance to outer transverse forces endeavouring to break the arch profile.

A seventh aspect of the present invention is a permanent support for a roadway constituted by 65 arch sections as hereinbefore defined, each arch 130

section being independent of and separate from its adjacent arch section and being releasably tied thereto.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: —

Fig. 1 is a perspective view of a concrete base panel;

Figs. 2 and 2A are respective perspective views of alternative concrete arch panels;

Fig. 3 illustrates a steel base panel and one form of tie device;

Figs. 4 to 4D are respective perspective views of alternative steel arch panels;

Fig. 5 is an exploded perspective view of an alternative device;

Fig. 6 is a perspective view of the tie device tying two adjacent panejs together;

Fig. 7 is a perspective view of a second form of tie device;

Fig. 8 is a perspective view of a third form of tie device;

Fig. 9 is a perspective view of arch sections formed by the present invention;

Fig. 10 is a half end view of apparatus for assembling the arch sections in position;

Fig. 11 is a view in the direction of arrow A in Fig. 10;

Fig. 12 is a perspective view of a roadway showing the apparatus of Figs. 10 and 11 in use;

Fig. 13 is a perspective view of a roadway showing a variation of the apparatus in use; and

Fig. 14 is a perspective view of a roadway support and lining being constructed.

Referring to Fig. 1, the base panel 20 is of prefabricated concrete construction and of rectangular construction, its ground-engaging side 21 having a relatively substantial contact area with the ground to provide a wide distribution of strata loading.

It has a central rib 22 and defines two windows 23 for the purpose aforesaid, i.e. to permit packing therebetween and the earth strata.

Each side 24 other than the side 21 is formed with two slots 25.

Each arch panel 26 (Figs. 2 and 2A) also of prefabricated concrete construction and rectangular construction is curved in one plane as can be seen and also has a central rib 27. Each of its sides 28 are formed with two slots 29. Its windows are infilled with concrete of lesser thickness than the sides 28 as indicated at 30 (Fig. 2) save at areas 31 in the region of the slots 29 or with mesh reinforcement 32 (Fig. 2A).

The profile outline into which the panels 26 are finally assembled will be semi-circular, mounted on straight or splayed base panels 20.

The panel sides which are butted together to form an arch section are serrated to facilitate matching union and resistance to transverse forces. The curves sides of panels 26 and the vertical sides of panels 20 are plain finished.

The panels are for example 1 yard/metre wide and have three major ribs 22,24 in the case of

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panels 20 and 27,28 in the case of panels 16 each of dimension 6" x 3".

The panels 20,26 are normally tied together to form an arch section by nuts and bolts but they 5 may instead be tied together by tie devices incorporating a wedging principle (see Figs. 3, 5 and 6 and Figs. 7 and 8).

The tie device (see Figs. 3, 5 and 6) comprises a shear locking plate 33 which locks together the 10 panels to establish the arch profile. This plate 33 is made of spring steel, is of L-configuration (Figs. 5 and 6) with a slot 34 in the longer of its two limbs 35,36 and cooperates with a serrated wedge 37. In Fig. 3, the plate 33A is also made of spring steel -15 but is of T-configuration with a slot 34A in its stem 35A normal to its crossbar 36A. A serrated wedge 37A cooperates with the plate 33A by engaging in slot 34A. This tie device (Fig. 3 or Figs. 5 and 6) gives the following advantages: — 20 a) To lock it in place (see Fig. 3 or 6) only requires a hammer or similar instrument — no special tools such as spanners.

b) Using the serrated wedge 37 or 37A against the lower plate limb 31 or crossbar 31A which has

25 a smaller negative taper, produces a high tensile locking force, which remains constant.

c) The plate 33 or 33A also provides, if necessary, additional shear resistance to outer transverse forces endeavouring to break the arch

30 profile.

d) The design of the locking plate and wedge is such, that if the arch is required to be dismantled, simply by using a lever or bar, the wedge can be dislodged sideways.

35 The assembly of adjacent panels, for example arch panels 26, is self-evident from Fig. 6 of the drawings.

Reference is now made to Figs. 7 and 8 which illustrate alternative tie devices.

40 In Fig. 7, the tie device comprises a locking pin 38 having an enlarged base 39, a head 40 and a flattened stem 41. A spring steel wedge 42 cooperates with the pin 38 and is slotted at 43 to engage the pin stem 41, the width of the slot 43 45 being less than the diameter of the pin head 40.

To couple two panels P1 and P2 together and which in this instance have channel section sides for example, it is only necessary to insert the pin 38 into registering slots until the base 39 abuts 50 the side of panel P1 and then to drive the wedge 42 under the pin head 40 and around the pin stem 41.

In Fig. 8, the tie device comprises a U-shaped . locking element 44 whereof the ends 45 are 55 splayed outwards and a wedge-shaped locking pin 46 with a right-angled extension 47 to facilitate hammering.

In use, the locking element 44 is inserted through registering slots and then turned through 60 90° until the ends 45 engage panel P1 and then the locking pin 46 is hammered in between panel P2 and the locking element 44.

The base panels may, if desired, be provided with a yielding facility and be formed of composite 65 materials.

The three major ribs of each panel provide high resistance ground pressure at 15" centres.

Reference is now made to Figs. 3 to 4D.

In Fig. 4, the prefabricated steel arch panel is constituted by two T-bars 48 curved in the direction of arch joined by three cross-strips 49. The rectangular frame formed is infilled with steel wire mesh 50 and the outer cross-strips 49 are slotted as at 51 to receive nuts and bolts or wedging tie devices.

In Fig. 4A, the prefabricated steel arch panel is defined by four equi-spaced L-members 52 curved in the arch direction, all bridged and joined by two cross-strips 53 to define a rectangular frame infilled with steel wire mesh 54. The four sides of this frame are slotted as at 55 to receive nuts and bolts or wedging tie devices.

Fig. 4B, shows two prefabricated steel panels as described with reference to Fig. 4A of adjacent arch sections being connected by nuts 56 and bolts 57.

In Fig. 4C, each panel is defined by two curved L-shaped bars 58 joined by three cross-strips 59, the panels being shown as being connected by nuts and bolts.

In Fig. 4D, each panel is defined by two curved channel-shaped bars 60 joined by three cross-strips 61, the panels again being shown as being connected by nuts and bolts.

It will be manifest that a variety of bar sections can be used in the production of prefabricated steel panels.

Fig. 3 shows a steel base panel constituted by two channel members 62 bridged by a top cross-strip 63 and by wire steel mesh 64 defining a wall. This assembly is supported by two channel legs 65 having ground-engaging plates 66. The channel members 62 and legs 65 are vertically elongatedly slotted as indicated at 67, and the legs 65 rest within the channel members 62 with intervening resilient packing 68 and are adjustably secured together by tie devices 33A and 37A as shown.

The steel base panel is clear of the ground to permit, inter alia, pack forming.

Strip 63 is slotted for the attachment thereto of arch panels.

The aforesaid prefabricated base and arch panels, whether of steel or concrete, can be readily assembled to form arch sections 70 (see Fig. 9). Adjacent arch sections can be butted and bolted together, or otherwise tied together to provide a continuous support and lining for a mine roadway.

In Fig. 9 it can be seen that each arch section is constituted by two base panels 71 and two long arch panels 72. There may, alternatively, be three arch panels 72, or four arch panels for example. Two or three arch panels are preferred.

The length of the arch panels in the direction of curvature is selected to suit requirements.

It can be seen that packing as indicated at 73 can be effected between the arch sections 70 and the earth strata 74.

Reference is made to Figs. 10 to 12.

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In Fig. 12, there is shown a roadway supported and lined by arch sections 70 incorporating two arch panels 72 as illustrated in Fig. 9.

As the roadway is advanced it is also necessary 5 to advance the support and lining to ensure that the miners are always under a protective shield, and apparatus is provided for effecting erection of the forward arch sections.

As the roadway support and lining advances 10 there is laid a guide rail 75 along the base panels 71 at each side. These guide rails 75 may be permanent or detachable for use in forward locations of the roadway as the support and lining advance.

15 The apparatus for use in erecting the arch sections is a shuttle comprising at each side an elongate roller carriage 76 to each of which is connected an arcuate frame 77. The two frames 77 define an arch frame and at their junction 20 slidably mount a pusher member 78. This pusher member 78 is engaged by an arm 79 of an erector handle 80 pivoted on one of the frames 77 and normally lying within the frame 77.

In use, when the roadway is sufficiently cleared 25 for erection of another arch section, the miners locate on the arch frame two arch panels 72 and they push the shuttle to a position where the arch frame lies forwardly of the erected roadway cover and lining. They pull the handle 80 inwardly which 30 causes the arm 79 to pivot upwardly and so cause the pusher member 78 to move upwardly and urge the arch panels 72 into alignment with the immediately previously erected arch panels. The miners then butt the supported arch panels 35 against the erected arch panels and bolt them together. The shuttle is withdrawn and a base panel 71 fitted underneath and into butting relationship with each arch panel. They then bolt the base and arch panels 71 and 72 together, and 40 finally bolt the adjacent base panels together.

It will be manifest from the above that the miners are always underneath a protective structure even when erecting the new arch section.

45 it is considered that a second pusher member could be suitably linked to the handle 80 to act on the arch panel so that it is aligned over its entire arcuate length with the previously erected arch panel.

50 The arch panels may be bolted together before being elevated and will be bolted together if three arch panels are employed.

It will be manifest that instead of the simple mechanical arrangement shown, the pusher 55 member could be a pair of hydraulic rams operated remotely from a hydraulic power pack by a miner.

It is also envisaged that the shuttle may be powered hydraulically along the track. 60 A magazine may be built into the shuttle (see Fig. 13) by providing the carriage 76 along its length with arch frames 77 to receive and hold arch panels only the forward arch frame incorporating the arch panel elevating means. In 65 this instance the pusher member is preferably a hydraulic ram arrangement 81 operated from a hydraulic pump 82.

It is possible when mining by "the drill and fire" method to advance a shuttle which also incorporates a magazine to advance the shuttle to cover the rubble (see Fig. 13) and permit same to be cleared safely by the miners before withdrawing same to secure the forward arch section in position to the leading end of the established support and lining arch construction.

Reference is now made to Fig. 14 which shows a roadway with the arch construction broken away and with a shuttle incorporating a magazine generally indicated at 83.

The prefabricated panels 71 and 72 are located above ground level onto trolleys 84. The latter arrive at the arch construction site by hoist and railway.

The panels are transferred from the trolleys 84 to a magazine and shuttle 83 by a crawler base machine 85.

The crawler base machine 85 is situated at the roadside and fitted to one side are two adjustable stabilizer arms 86. Normally the arms 86 will be retracted and lie over the crawler track and when in use, they are at right angles to the machine body as shown.

The machine 85 is fitted with an extensible boom arm 87 at the end of which is a powered clamp 88 which positively locates and locks onto each arch panel 72.

The clamp 88 is capable of 360° rotation.

A power pack 89 for the crawler base machine 85 also supplies hydraulic power to the magazine and shuttle 83 via flexible hoses (not shown).

The magazine and shuttle 83 instead of being mounted on guide rails may be mounted on a crawler base. Within the magazine are powered facilities such as rams (not shown) to move the panels forward until they finally rest on the erector arch frame.

This erector arch frame may comprise a ram-operated caliper-movement frame which when actuated, moves the complete arch frame outwards until it comes into contact with the ground strata. Within the caliper frame is provision to bring the panels together in union abutment, after which they are secured together.

It is noted that the base panels 10 may be either post-loaded and fitted with load bearing arrangements or lowered onto the floor position and possibly backfilled.

The invention therefore also encompasses a mechanical handling system for use in roadway support and lining erection and comprising a trolley for conveying the prefabricated panels from above ground to the roadway site, a panel-storage magazine and shuttle unit from which assembled arch panels are elevated into position against the strata to be supported, and a panel-transfer machine having a pivotal boom with a panel-clamp at one end for disposition between the trolley and magazine and shuttle unit.

Finally the invention encompasses apparatus for use in erecting arch sections comprising a

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carriage, an arch panel support frame, and means associated with the latter for elevating arch panels into alignment with previously erected arch panels.

5 The apparatus may incorporate a magazine to support a supply of arch panels.

The arch support frame may be of a length sufficient to support more than one pair of arch panels.

Claims

10 CLAIMS

1. An underground roadway supporting and lining means comprising an arch section consisting of a pair of laterally-spaced base panels bridged and interconnected by at least one arch

15 panel.

2. Means as claimed in claim 1 comprising a number of arch sections for disposition in butting relationship along the length of the roadway.

3. Means as claimed in claim 1 or 2, in which

20 the base panels are interconnected by a plurality of arch panels.

4. Means as claimed in any one of claims 1 to 3, in which the base panels and arch panels are releasably tied together by tie devices.

25 5. Means as claimed in any one of claims 2 to 4 in which the butting arch sections are releasably tied together by tie devices.

6. Means as claimed in any one of claims 1 to 5, comprising a prefabricated concrete base panel

30 of rectangular configuration having a ground-engaging side of relatively large area, and its other three sides, each being adapted to receive at least one tie device.

7. Means as claimed in any one of claims 1 to 5

35 comprising a prefabricated steel base pane! of rectangular construction adjustably and possibly yieldingly supported clear of the ground by a pair of legs and with its upper side and possibly its vertical sides being adapted to receive at least one

40 tie device.

8. Means as claimed in any one of claims 1 to 7 comprising an arch panel of rectangular construction and curved in one plane whereby a number assembled together in butting relationship

45 define a semi-circular or other arch form and with at least the two panel sides normal to said plane each being adapted to receive at least one tie device.

9. Means as claimed in claim 8, in which the

.50 butting sides of adjacent panels prefabricated in concrete are serrated or rendered otherwise non-smooth to facilitate matching connection and resistance to transverse forces.

10. Means as claimed in any one of claims 1 to

55 9 in which each panel (base or arch) preferably has a rib normal to and joining the butting sides or parallel with the butting sides.

11. Means as claimed in claim 10 in which the sides and rib of a concrete base panel define two

60 open windows to permit passage of material therethrough outside the arch for pack construction or to facilitate back-filling or grouting of adjacent strata.

12. Means as claimed in claim 10 comprising a

65 concrete arch panel in which the sides and rib define windows in-filled with concrete or mesh reinforcement.

13. Means as claimed in claim 8 in which the arch panel is of steel and is formed of lateral ribs

70 extending in the direction of arching of L or H or T or channel section welded to connecting plates.

14. Means as claimed in claim 7 or 13 in which each panel has one or more connecting plates joining the lateral ribs intermediate the butting

75 plates or vice versa, or the butting plates or lateral ribs are bridged by one or more sectioned ribs.

15. Means as claimed in claim 14 in which the panel surface is covered by steel wire mesh or other material such as corrugated sheeting welded

80 to the rectangular frame components.

16. Means as claimed in any one of claims 1 to 15, in which each side of each panel (base or arch) adapted to receive at least one tie device is preferably slotted at two locations.

85 17. Means as claimed in claim 16 in which the tie device comprises a first locking element adapted for passage through registering slots in adjacent panels into abutment with one of the panels, and a second locking element adapted to

90 be wedged between a formation on the first locking element and the other panel.

18. Means as claimed in claim 17 in which the tie device comprises a substantially L or T-shaped shear locking plate with an open-sided slot in

95 one limb, and a wedge adapted for releasable engagement in said slot.

19. Means as claimed in claim 18, in which the locking plate is formed of spring steel and the wedge is serrated on its plate-engaging surface.

100 20. Means as claimed in claim 16 in which the tie device comprises a headed locking pin with an enlarged base and a slotted spring steel wedge, the pin having flat opposed surfaces for engagement by the wedge slot which has a lesser

105 width dimension than that of the locking pin head.

21. Means as claimed in claim 16, in which the tie device comprises a locking element in the form of a U with the limbs of the U partly turned outwards, and a wedge shaped locking pin.

110 22. A permanent support and lining for an underground roadway constituted by arch sections as claimed in any one of the preceding claims, each arch section being independent of and separate from its adjacent arch section and

115 being releasably tied thereto.

23. A method of supporting and lining an underground roadway comprising the steps of providing prefabricated base panels and arch panels to define an arch section, and tying same to

120 a previously erected arch section.

24. A method as claimed in claim 23 comprising the steps of conveying at least one prefabricated arch panel to a desired location, elevating it into alignment with a previously

125 erected arch panel and tying them together, disposing a prefabricated base panel under the lower end of the arch panel, and tying the base panel and arch panel together.

25. Apparatus for use in erecting arch sections

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to support and line an underground roadway, the apparatus comprising a carriage movable along the roadway, an arch support frame carried by the carriage and adapted to support at least one 5 prefabricated arch panel, and means associated with the arch support frame for elevating an arch panel into alignment with a previously erected arch panel.

26. Apparatus as claimed in claim 25, in which 10 the carriage supports a plurality of arch support frames which provide a magazine facility, only the leading arch support frame having arch panel elevating means associated with it.

27. Apparatus as claimed in claim 25 or 26 in 15 which the elevating means is a pusher member slidably supported at the centre of the arch support frame.

28. Apparatus as claimed in claim 27 in which the pusher member is movable by a pivotal arm

20 secured to the arch support frame and operated by a handle to which it is connected.

29. Apparatus as claimed in claim 27 in which the pusher member is hydraulically operated.

30. An underground roadway supporting and 25 lining means substantially as hereinbefore described with reference to the accompanying drawings.

31. A method of supporting and lining an underground roadway, substantially as

30 hereinbefore described with reference to the accompanying drawings.

32. Apparatus for use in supporting and lining an underground roadway substantially as hereinbefore described.

35 33. A prefabricated concrete base panel of rectangular configuration having a ground-engaging side of relatively large area, and its other three sides, each being adapted to receive at least one tie device.

40 34. A prefabricated steel base panel of rectangular construction adjustably and possibly yieldingly supported clear of the ground by a pair of legs and with its upper side and possibly its vertical sides being adapted to receive at least one 45 tie device.

35. An arch panel of rectangular construction and curved in one plane whereby a number assembled together in butting relationship define a semi-circular or other arch form and with at least 50 the two panel sides normal to said plane each being adapted to receive at least one tie device.

36. A tie device comprising a first locking element adapted for passage through registering slots in adjacent penels into abutment with one of

55 the panels, and a second locking element adapated to be wedged between a formation on the first locking element and the other panel.

■ 37. A steel base panel having a steel wire mesh wall adjustably and resiliently supported clear of 60 the ground.

Printed for

Her

Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.