GB2150950A

GB2150950A - Wire netting for use in tunnels and the like

Info

Publication number: GB2150950A
Application number: GB08430186A
Authority: GB
Inventors: Peter Rossler
Original assignee: ROESLER DRAHT GmbH
Current assignee: ROESLER DRAHT GmbH
Priority date: 1983-11-30
Filing date: 1984-11-29
Publication date: 1985-07-10
Also published as: FR2555659B1; GB8430186D0; FR2555659A1; DE3441336C2; DE3441336A1; GB2150950B

Abstract

A mat (1) of wire netting for use in tunnels and underground structural work comprises longitudinally extending wires (2) and transverse wires (3) which are connected together to form a first set of meshes (4), the longitudinal wires (2) being smaller in diameter than the transverse wires (3). An additional set of meshes (5) of larger size than the meshes (4) are formed for identifying the required locations of and,for receiving respective anchor elements (29) for mounting the wire mat (1) in a required position. Each side of each mesh (5) may be defined by at least two elongate elements (6, 7; 8, 9) spaced more closely to each other than the wires (2, 3) defining the meshes (4) alternatively the edges of the meshes (5) may include reinforcing elements. Further, the meshes (4) are arranged in bands (16 to 27), the width of the meshes being greater in the outer bands which are to be disposed near the floor of the tunnel. In an alternative embodiment instead of forming meshes (5), apertures for the anchor elements are formed by removing intersection regions of the meshes (4). <IMAGE>

Description

SPECIFICATION Wire net for tunnel and underground structural work, headway timbering and the like The invention relates to a wire net for tunnel and underground structural work, headway timbering and the like, which comprises intersecting longitudinal and transverse wires which form meshes with one another, wherein the longitudinal wires have a smaller diameter than the transverse wires.

When driving tunnel-like stretches in mountainous ground, wire nets and the like are used as protection against falling stones, and these wire nets are laid transversely to the tunnel path on the overlying rock. It is further known to secure the wire mats or wire nets, which are for protection from rock falls, by means of anchors to the rock.

Depending on the type of rock a plurality of anchors is placed over a specific peripheral area of the tunnel, wherein the distances between the holding anchors in the longitudinal and the transverse direction of the tunnel is exactly stipulated and can be varied by the mining authority. The anchors are placed in previously prepared bores in the rock and are secured in the bores by suitable means, e.g. by adhesive connections and the like.

Anchor plates are used to hold the wire net or the like and these plates are retained by nuts screwed on the threaded heads of the anchors and hold the wire net pressed against the surface of the rock body.

To produce the bores in the rock body the positions for the anchor holes are marked in white on the arched roof of the tunnel using a measuring line and a surveyor's pole. The ridge holes are bored first of all. The wire net is fitted in the ridge with two anchors and then rolled out. Then the white spots on the rock are looked for. Finally the anchor hole is bored through the wire net. Painting the anchor positions on the tunnel surface is timeconsuming and energy-consuming. Painting a diagram of the holes on the tunnel-like surface of the rock is also not much use because when the wire net is in place, the dots painted on the rock are hard to find and to recognise.

The aim of the invention is to produce a wire net for the timbering of a tunnel or the like in the rock, with which visible marks are formed for the anchor bore or anchor holes by the construction of the wire net itself and the arrangement and distribution of the meshes. According to the invention the solution lies in the fact that the wire net has meshes whose edges in the longitudinal- and transverse direction are framed by at least two wires or steel bands or the like, which lie closer together than with the meshes of the adjacent areas, and in the fact that the width of the meshes in the longitudinal direction of the mat is provided to be different in areas. Thus the areas from the centre of the mat path can be sectioned in mirror-image fashion with differently dimensioned mesh widths.

By means of a wire net design of this type, clearly visible indications are produced through the construction of the meshes themselves and their distribution and spacing over the wire net, as to where the anchors are respectively to be placed according to a predetermined schematic hole diagram. The wire net itself forms a template, so to speak, for the respective hole scheme to be used.

At the same time the meshes of the wire net, which are intended for the placing and arrangement of the anchors, are reinforced at the edges.

At least double the tensile strength is obtained in the edge wires of the meshes by placing a plurality of wires or the like close together on the mesh. By means of the different dimensions of the mesh widths in the different areas between the meshes with edge wires or the like lying close together, there is an adaptation to the load condition of the retaining system from the ridge to the floor. The wire net used as protection against rock fall is stressed more greatly at the ridge of the tunnel or in the ridge zone than in the areas lying below and leading to the floor. Through the different size of the meshes in the different mesh areas of the mat a substantial saving is made in wires where the stress from the rock is less. A desired specific resistance moment can be achieved for the wire net.

The meshes framed by at least two wires or the like preferably have a square outline which is adapted to the circular cross section of the drill or the anchor.

As regards the surfaces of the overlying rock of the section, the tunnel or the like, it may be that these surfaces are extremeley uneven. They are more or less full of fissures if, for example, fragmented parts are broken out of the roof. In cases like this the wire net at the meshes receiving the anchors needs reinforcements running in the longitudinal direction of the wire net sheet so as to be able to take forces that are very great in part, without the wires, particularly the longitudinal wires, of the wire net tearing or breaking. The reinforcements can be constructed in various ways.

The longitudinal anchor transverse wires framing the relevant meshes can have a larger diameter than the other wires of the wire net. In addition the one wire or both wires of the longitudinal wires lying closely together and limiting the meshes can be reinforced by cable wires or other steel wires.

Thus the reinforcement cable wires or the like can be alternately guided round the intersection points of the associated longitudinal wire. A longitudinal wire of the edge wires can also be replaced directly by a cable wire of larger diameter.

In addition to stiffen the edge wires a perforated steel band can also be used which is advantageous with the outer lying edge wires. Also the longitudinal wire lying on the inside and limiting the mesh can be replaced by a milled hoop iron which is welded to the transverse wires, whereby the hoop iron can also be provided with at least one longitudinal rib. Another type of reinforcement comprises at least one longitudinal wire or the milled hoop iron or a steel band iron being enclosed by angle shaped bands or a U-shaped band, with the shaped bands being welded to the transverse wires.

Several reinforcement measures can also be combined according to the stress that is to be expected.

According to a further feature of the invention, the wire net, as an oblong wire net sheet of at least two wires or the like, has framed meshes which run in rows in the longitudinal and transverse direction of the sheet. Thus the rows should have the same distance between them in each direction. In special cases the distance can also be kept variable. Preferably the rows of meshes framed respectively by at least two wires or the like are arranged to be closer together than in the transverse direction of the sheet. A construction of the wire net sheet of this type makes possible a hole structure for the anchors to be placed which originates from a specific fundamental system.

According to another feature of the invention the wire net, as an oblong wire net sheet, can have meshes in the longitudinal centre which in the transverse direction are framed by more closely adjacent transverse wires than the relevant meshes of the adjacent areas in the longitudinal direction of the sheet. For example the row of meshes in the middle of the wire net mats can have more than two closely adjacent transverse wires for each side of the mesh compared with the other meshes of the adjacent areas reinforced with edge wires or the like. The centre marking of the mat that thus results can hence be made to correspond with the centre of the axis of the tunnel arch and can be anchored first.

Advantageously the longitudinal wires have the same distance between them in the transverse direction of the wire net sheet.

On the longitudinal sides of the wire net sheet advantageously at least two rows of meshes in the transverse direction of the sheet should be adjacent to the outer longitudinal row of the meshes framed by at least two closely adjacent wires or the like. Thus there is obtained a satisfactory and secure overlapping ratio of two wire net sheets laid to overlap on the longitudinal sides. On one side care is taken that the outer row of anchors lies at a distance from the longitudinal edge of the wire net sheet. Both adjacently situated wire net sheets are securely held by a common anchor. The distance from meshes framed by at least tw.o wires to the longitudinal edge of the wire net sheet should be at least so great that it corresponds at least to the radius of the anchor plate. In this way the overlapping zone is also satisfactorily and reliably held firmly against the rock body.

Onto the last transverse row of the meshes framed by at least two closely adjacent wires there can be arranged in the longitudinal direction of the sheet rows of meshes which consecutively become larger in the longitudinal direction than the other areas between the meshes framed by at least two closely adjacent wires. This means that the parts of the wire net sheet located in the lower sides of the tunnel can be handled comparatively easily, e.g. by folding or by laying on the bottom of the tunnel etc.

According to a varied construction of the invention, a regularly constructed wire net can have, in the longitudinal and/or transverse direction, apertures from whose meshes the intersecting wires have been removed, and so there is a mesh whose dimensions correspond to the four meshes meeting at the intersection. The spacing and distribution of the meshes is provided in accordance with the fundamental system of the anchor aperture structure. Thus it is advisable that the wires forming the intersection respectively project over the edge wires of the aperture mesh formed for the anchor. The wires therefore remain welded to the edge wires of the large mesh so that the large mesh has the appropriate rigidity. A wire net or wire net sheet of this type can be used in falls that can be held in particularly easy manner.

In the delivery state the wire net sheet can form rolls running from the common longitudinal centre in opposite directions with respect to one another, to simplify manoeuvring. In this form the wire net sheet is an easily handled part. If the wire net sheet consists of two sheet parts that are constructed in mirror-image fashion to one another, with respect to the transverse rows of meshes which are framed by at least two wires respectively, then the sheet parts can form rolls which overlap in the longitudinal direction and run in opposite directions to each other from the overlapping zone. A design like this is also an easily usable unit.

The wire nets are principally those with which the intersecting longitudinal and transverse wires are welded together.

The invention will be described below by means of the embodiment examples shown in the drawings.

Figure 1 shows a schematic plan view of the wire net of the invention.

Figure 2 shows, also in schematic plan view, a wire net of the invention which is a piece of half a wire net sheet, wherein in use the segments are arranged to overlap in the centre.

Figures 3 to 15 show sections of wire net sheets, also respectively in plan view and in elevation, with which edge wires are constructed to be reinforced in various ways for the meshes receiving the anchors.

Figures 16 and 17 show a rolled-up wire net sheet according to the invention, with which the sheet forms rolls running in opposite directions to each other on the common longitudinal centre, or two segments for each half wire net sheet are arranged to overlap in the centre.

Figures 18 and 19 show a modification of the wire net according to the invention in simplified form, wherein Fig. 19 shows an enlargement of an aperture point for an anchor.

Fig. 1 shows a wire net or a wire net sheet 1 for use in tunnel construction and the like, wherein the wire net has intersecting longitudinal wires 2 and transverse wires 3 which enclose a first set of meshes 4 between them. The intersecting longitudinal and transverse wires are advantageously welded together. A mutual plaiting or interweaving can also be used. The longitudinal wires 2 should have a smaller diameter than the transverse wires 3, so that it is possible to convey the wire net sheet in rolls in the longitudinal direction.

A wire net or the wire net sheet 1 has an additional set of meshes 5 whose edges are framed in the longitudinal and transverse direction by at least two wires 6 and 7 and 8 and 9. The wires in each pair of wires 6, 7 and 8, 9 lie closer together than with the meshes 4, which are formed respectively only from one longitudinal wire or transverse wire.

At particular points, preferably in the longitudinal centre 11 of the wire net sheet 1 several transverse wires 12 and 13 lying closely together can be provided as edge wires for the meshes 5 compared with the pairs of wires 6 and 7. The centre of the wire net sheet 1 in use is brought to lie in the tunnel roof. Thus it is also possible that the rows of meshes adjacent to the longitudinal centre, the meshes of which are framed by two transverse wires, have more than two transverse wires respectively, instead of the pair of transverse wires.

This depends on the type of rock in the tunnel to be made safe.

The wire net sheet 1 is further preferably constructed in such a way that the width of the meshes in the direction of opposite sides of the wire net is made to be different. As can be seen in the wire net sheet of Fig. 1, areas 15, 16, 17, 18 adjoin the common longitudinal centre 11 to both sides, and with these areas the longitudinal and transverse wires 2 and 3 form meshes of square shape with one another. In the other areas 20 to 26, the respective transverse wires are provided to be at a greater distance from one another, whilst the longitudinal wires 2 retain their distances between one another. Hence there are rectangular meshes. At the end parts of the wire net sheet 1 there is preferably an area 27, in which the transverse wires are provided to be even further apart than with the previous areas. Area 27 is the covering of the beginning of the tunnel near the floor.

To secure the tunnel beginning by means of the wire net sheet against fall of rock, the wire net can be kept lighter in cross section in the lower part towards the floor of the tunnel than in the area of the roof and the areas adjoining the roof.

In practice the width of the meshes of areas 15 to 18 - seen in the longitudinal direction of the wire net sheet 1 - can be 50 mm, areas 19 to 26 62.5 mm and area 27 88.5 mm. The width of areas 10 to 26 is continuously constant from area to area so that in areas 20 to 26 there are only four rows of meshes between the rows of meshes 5, in contrast to five rows of meshes in areas 15 to 18. In this example the meshes 5 can be 75 mm square. This means that the spacing of the meshes with the frame of respectively two closely adjacent wires remains the same right up to the penultimate area, i.e. in the example is 375 mm.

In this way one can get a basic distribution sysL tem for an anchor hole structure. In Fig. 1 by way of example an anchor hole structure indicated by black dots is marked onto the wire net sheet 1. In the centre area of the middle row of meshes 11 the respectively outer-lying mesh is provided with edge reinforcement for receiving a retaining anchor, whilst the middle mesh with edge reinforcement is free. Then the next meshes with reinforcement are fixed in the longitudinally-running middle row of meshes with reinforced frame for receiving an anchor. In the direction of the end parts the next but one meshes are then provided with edge reinforcement for receiving an anchor.Naturally in the middle zone of the wire net sheet 1, i.e. in the ridge zone, the meshes with edge reinforcement that are free in the anchor hole structure illustrated can also be provided with an anchor. The anchor hole structure is different according to the type of rock, but one can stick to the basic system of wire net sheet provided by the meshes with edge reinforcement.

The meshes with edge reinforcement are clearly visible and accessible and therefore are easy to find or locate in situ. The anchor hole system in the wire net sheet 1 of Fig. 1, recognisable by the anchor 29 that is drawn in, uses the basic system which results from the arrangement of the meshes with edge reinforcement, whereby according to the structure of the rock a modified anchor hole system can easily be used for the anchor 29.

In Fig. 2 there is shown a wire net sheet 30 which corresponds to approximately half the wire net sheet 1 of Fig. 1. With the row of meshes 11 which has meshes which are reinforced by three transverse wires in the transverse direction of the sheet, at least two to four further rows of meshes 31 can adjoin and are used to overlap with a wire net sheet 30 lying in mirror-image fashion. Thus the row of meshes 11 of both wire net sheets 30 lying in mirror-image fashion with respect to each other should be held together on top of each other with the anchor plates by means of the common anchor 29. The remaining distribution of the meshes and the areas of the half wire net sheet 30 corresponds to that of wire net sheet 1.

Figs. 3 to 15 show different types of reinforcement of the edge zones on the meshes receiving the anchor, in particular in the longitudinal direction of the wire net sheet.

In the embodiment of Fig. 3, 4a, 4b, the closely adjacent longitudinal wires 40 framing the meshes have a larger diameter than the other longitudinal wires 2 of the wire net sheet. According to Fig. 4b the longitudinal wires limiting the meshes 5 can be formed of at least two wires 45a, 45b that lie closely together. Advantageously these wires 45a, 45b have a larger diameter than the other longitu-4 dinal wires 2. The reinforcement by stronger wires 40, 45a, 45b, is dependent on the load that is to be expected. Whilst the wires 2 can have e.g. a diameter of 3 mm, for the wires 40, 45a, 45b, thicknesses of approximately 4 mm in diameter or even more can be selected.

The reinforcement of the anchor mesh 5 is produced, according to the example of Fig. 5 and 6, in such a way that one longitudinal wire 2 or both longitudinal wires of the closely adjacent longitudinal wires limiting the anchor mesh, is or are reinforced respectively by at least one cable wire 41 or a further steel wire. The reinforcement cable wires 41 or further steel wires are guided alternately round the intersections 42 between the longitudinal and transverse wires of the associated longitudinal wire 2.

In the embodiment of Fig. 7 and 8, the outerlying longitudinal wires 2 of the closely-adjacent wires limiting the meshes 5 are reinforced by a perforated steel band 43. The apertures 44 on the steel band are so distributed that one aperture of the steel band 43 comes to lie at the intersections 42 between the longitudinal wires and the transverse wires.

In Figs. 9 to 15 further embodiments for the reinforcement of the longitudinal edges of the anchor meshes 5 are shown. The other inner-lying longitudinal wire limiting the mesh 5 can be replaced by a milled hoop iron 46 or 47. The milled hoop iron 46, 47 is welded to the transverse wires 3. Advantageously the milled hoop iron 46, 37 has at least one longitudinal rib 48. A milled hoop iron 49 or a steel hoop iron 50 can be enclosed by two angle shaped bands 51, 52 or a U-shaped band 53. The angle-shaped bands 51, 52 or the U-shaped band 53 are welded to the transverse wires 3. In addition at least one longitudinal wire 54 or two adjacent longitudinal wires 54 can be rolled into a U-shaped band 55 or 56. The U-shaped band 55, 56 is thus welded to the transverse wires 3.The appropriate reinforcement for the anchor meshes 5 in the longitudinal direction of the wire net sheet can be used according to the type and composition of the roof.

So as to be able to manoeuvre the wire net sheet it is advisable to provide this in rolls. With a wire net sheet 1 with a particularly reinforced row of meshes provided in the middle of the length of the sheet, the sheet portions extending in the longitudinal direction of the sheet can be rolled up to form a roll 34 and 35 with an oppositely-directed winding, whereby the middle row of meshes 11 is between the rolls. In this way the handling and laying of the wire net sheet is substantially simplified (Fig. 16).

If two wire net sheets 30 are used which are to be laid in the transverse direction of the tunnel in mirror-image fashion to each other, each wire net sheet is also to be laid to form a roll 36, 37, so that the rows of meshes 11 with the special reinforcement coincide and the adjoining mesh parts 31 overlap in the direction of both sides (Fig. 17). The overlap can be secured in suitable fashion, e.g. by reinforcement wires or the like.

In many cases it may be sufficient to use a simplified wire net 58 with which the meshes of the intersecting longitudinal and transverse wires do not have any reinforcement at all, but are limited only by longitudinal and transverse wires that are single (Fig. 18, 19). However, it is advisable that a wire net 58 of this type or a wire net sheet of this type already has apertures for a basic anchor system for use with different anchor hole structures.

The distribution and spacing of the apertures can be substantially the same as with the wire net sheets 1 and 30. The apertures 59 with the wire net 58 with the intersecting longitudinal wires 60 and transverse wires 61 are preferably produced by the fact that a wire net of four adjacent small meshes 62 is no longer present, e.g. is removed by stamp ing or the like. The result is an aperture mesh 59 of a size equal to four adjacent small meshes 62.

Thus it is advantageous if the cut-off longitudinal and transverse wires 60, 61 respectively project over the edge wires of the aperture mesh 59 so as to obtain the junction of the intersecting wires on the larger aperture meshes 59. The distribution of these aperture meshes 59 corresponds to a basic system, from which various anchor hole systems or systems for placing the anchors can be achieved.

Claims

1. A mat of wire netting for use in tunnel and underground structural work, headway timbering and the like and comprising longitudinally extending wires and transverse wires which are con nected together to form a first set of meshes of the wire mat, the longitudinal wires being smaller in cross-sectional areas than the transverse wires, and in which: an additional set of meshes is formed in the wire mat, such meshes serving for identifying the required location of and for receiving respective anchor elements for mounting the wire mat in a required position; each mesh of the additonal set is framed on all sides by at least two laterally spaced elongate elements which are spaced more closely to each other than the spacing-apart of opposed sides of an adjacent mesh of the first set; and the meshes of the first set are arranged in transversely extending bands which are spaced apart along the length of the wire mat, the width of the meshes varying between one band and at least one other band.

2. A wire mesh according to claim 1, in which the meshes of the additional set are different in size than the meshes of the first set.

3. A wire mat according to claim 2, in which the meshes of the additional set are larger in size than the meshes of the first set.

4. A wire mat according to claim 1, in which the meshes of the additional set are square in outline.

5. A wire mat according to claim 1 or 2, in which each of the longitudinal sides of the meshes of the additional set is formed by a respective pair of longitudinal extending wires which are larger in diameter than longitudinally extending wires which define the first set of meshes.

6. A wire mat according to claim 1 or 2, in which each of the longitudinal sides of the meshes of the additional set is formed by two closely spaced pairs of longitudinally extending wires each of which is larger in diameter than longitudinally extending wires which define the first set of meshes.

7. A wire mat according to claim 1 or 2, in which one longitudinal wire or both longitudinal wires of the closely adjacent longitudinal wires limiting the meshes of the additional set are respectively reinforced by cable wires or other steel wires, and in which the reinforcement parts or the like are alternately guided round the intersection points in the associated longitudinal wire.

8. A wire mat according to claim 1 or 2, in which the outer-lying longitudinal wires of the closely adjacent wires limiting the additional set of meshes are reinforced by a perforated steel band, and in which at the intersection points of the longitudinal wires with the transverse wires, an aperture is provided in the steel band.

9. A wire net according to claim 1 or 2, in which the inner-lying longitudinal wire limiting the meshes is replaced by a milled hoop iron which is welded to the transverse wires.

10. A wire mat according to claim 9, in which the milled hoop iron has at least one longitudinal rib.

11. A wire mat according to claim 1 or 2, in which a milled hoop iron or a steel hoop iron is enclosed by two angle shaped bands or a Ushaped band, and in which the angle shaped bands or the U-shaped band is welded to the transverse wires.

12. A wire mat according to claim 1 or 2, in which at least one longitudinal wire is rolled into a U-shaped band and the U-shaped band is welded to the transverse wires.

13. A wire mat according to any one of claims 1 to 12 and formed as an oblong wire net sheet, in which the meshes of the additional set are framed by at least two wires, steel bands or the like, which run in rows in the longitudinal and transverse direction of the sheet, and in which the rows have the same distance between them in each direction.

14. A wire mat according to claim 13, in which the rows of the additional set of meshes are arranged to be closer together in the longitudinal direction of the sheet than in the transverse direction of the same.

15. A wire mat according to any one of claims 1 to 14, in which the wire mat, as an oblong wire net sheet, has meshes of the first set in the longitudinal centre, which are framed in the transverse direction of the sheet by more than two closely adjacent transverse wires, steel bands or the like, which as with the meshes of the additional set provided with reinforcement in the adjacent areas in the longitudinal direction of the sheet.

16. A wire mat according to any one of claims 1 to 15, in which the longitudinal wires, in the transverse direction of the wire mat, have the same distance between each other.

17. A wire mat according to any one of claims 1 to 16, in which the spacing apart of the rows of the additional set of meshes remains constant from area to area, when the mesh width is changed in the longitudinal direction.

18. A wire mat according to any one of claims 1 to 17, in which at least two mesh rows in the transverse direction of the mat adjoin an outer longitudinal row of the additional set of meshes.

19. A wire mat according to any one of claims 1 to 18, in which rows of the first set of meshes in the longitudinal direction of the wire mat are arranged successively onto the last transverse row of the additional set of meshes, and form a larger area than the previous areas.

20. A mat of wire netting for use in tunnel and underground structural work, headway timbering and the like, and comprising longitudinally extending wires and transverse wires which are connected together to form the meshes of the wire mat, with the longitudinal wires having a smaller diameter than the transverse wires, in which: apertures are formed in the wire mat at predetermined locations, for identifying the required location of and for receiving respective anchor elements to mount the wire mat in a required position; and the apertures have a size substantially equal to the size of four of the meshes of the wire mat.

21. A wire mat according to claim 20, in which the longitudinal and the transverse wires, which extend towards the respective apertures project respectively over the edge wires of the apertures.

21. A wire mat according to any one of claims 1 to 20, and formed into rolls running in counter direction to one another from a common longitudinal centre.

22. A wire mat according to any one of claims 1 to 21, and comprising two sheet portions that are arranged in mirror-image fashion to each other with respect to the longitudinal centre, and in which the sheet portions form rolls overlapping and running from the overlapping zone in opposite directions to one another.

23. A wire mat according to claim 1 and substantially as hereinbefore described with reference to, and as shown in Figures 1 to 17 of the accompanying drawings.

24. A wire mat according to claim 20 and substantially as hereinbefore described with reference to, and as shown in Figures 18 and 19 of the accompanying drawings.