GB2044333A

GB2044333A - Temporary Tunnel Support for Holing Operations in Tunnels of Underground Mines

Info

Publication number: GB2044333A
Application number: GB8000959A
Authority: GB
Original assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Current assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Priority date: 1979-01-12
Filing date: 1980-01-11
Publication date: 1980-10-15
Also published as: BE881117A; GB2044333B; FR2446377B1; FR2446377A1; DE2901054A1

Abstract

A temporary tunnel support (1) which can be advanced along the tunnel comprises three support arches (2, 3, 4) each having hydraulic prop supports (5, 6, 7) at their lower ends and supporting side bars (20, 21) against the sides of the tunnel and roof bars (23) against the roof of the tunnel. The lower ends of the arches are liked by double-acting cylinders (14) and an upper cylinder (15) is disposed below the roof. Each bar (20, 21, 23) can be slid backwards or forwards relative to the central arch (3) by rams (26). Working platforms and a jib for the installation of permanent arches may be mounted on the rear of the support, Fig. 1 (not shown). <IMAGE>

Description

SPECIFICATION Temporary Tunnel Support for Holing Operations in Tunnels of Underground Mines The invention relates to a temporary tunnel support for holing operations in tunnels of underground mines, comprising thrust girders which extend in the longitudinal direction of the tunnel and arched support frames which carry them, each thrust girder, extending beyond the support frames at the front and at the rear, being associated with an advance cylinder.

In connection with mining operations, the tunnels required for ventilation, for the transport of material and for manriding are in part subject to a great amount of stress. This applies particularly to haulage tunnels, but also to stone drifts which are being affected by workings. The flexible support system used in most cases in such tunnels makes it possible for the support to yield in certain areas to the pressure coming from the sides and roof of the tunnel. If the predetermined limits for telescoping are exceeded, or if a strong unilateral pressure prevents the tunnel support from being telescoped, the latter will be deformed and pushed into the interior of the tunnel. To this is added the fact that frequently not only the sides and the roof of a tunnel migrate into the interior of the tunnel but additionally also the floor of the tunnel can rise.Due to the considerabie reduction in the tunnel cross-section associated with this it is necessary to hole such tunnels. This means that, starting from a place where the tunnel crosssection is still adequate for the purpose, the crushed tunnel supports must be removed and replaced by new ones after the original tunnel cross-section has been restored by ripping out the tunnel roof and sides and/or by lowering of the floor.

Because of the adverse pressure conditions, the rock in these areas has undergone destruction to such an extent that it is inclined to spill out when the old lagging and the old tunnel supports are taken away. For this reason the supervising authorities have issued directions that, starting from the sound support arches already erected, extensions have to be provided by means of wooden beams or steel plates. The wooden beams or steel plates have to be set in place by hand. Apart from not always providing adequate safety to workers engaging in this task, this method of working, is extraordinarily expensive because it requires a multiplicity of further operational steps. In addition, success is doubtful because the covering with beams, or the placing of extension, may not give the required security against further collapse.

A so-called support shield is known in which the support beams, forming a shield roof and braced against a support frame, can be pressed forward individually or in groups with the aid of cylinder arrangements. This support shield is supported with its two support frames, consisting of two frames resting on floor sills which are rigidly connected to one another. These floor sills are run over rock bolts and are simultaneously braced. The disadvantage in this is the relatively high expenditure of labour connected with the production of the bolt holes for the rock bolts. It is also of disadvantge that the support frame is constructed of one piece so that it can be advanced only under full thrust. It is also necessary to keep the thrust exactly straight since it is otherwise not possible to move the floor sills along in the predetermined direction.This is of disadvantage, however, particularly with holing operations for which, as a rule, the known temporary tunnel support (Offenlegungsschrift 26 57 003) is to be used due to the fact that it is provided with support beams which can be pressed forward individually or in groups and which are scarfed appropriately.

It is the object of the invention to provide a support frame which can be used as a temporary tunnel support during holing work, which "walks" automatically, can be adapted to a large extent to changes in direction and cross-section and which guarantees that the holing work is executed safely and effectively.

According to the invention there is provided a temporary tunnel support for holing operations in tunnels of underground mines, comprising thrust girders which extend in the longitudinal direction of the tunnel and support frames which carry them, each thrust girder being associated with an advance cylinder and projecting past the respective support frame both at the front and at the rear, the support frame being formed of at least three support arches which are adapted to be moved independently of one another in the longitudinal direction of the tunnel and/or transversely with respect to the tunnel.

A support in accordance with the invention makes it possible to move it independently, and without affecting the thrust girders, in the longitudinal direction of the tunnel. During this process in each case only the support arch which is to be moved is partially relieved of its load in the transverse direction with respect to the tunnel, and can then be moved in the longitudinal direction of the tunnel. The two remaining support arches stay fully stressed in their support position and prevent any change from occurring in the cross-section, during the "walking" operation.

Any desired or required changes in the crosssection can be executed later without difficulties with the aid of the temporary tunnel support according to the invention.

Each support arch is preferably associated with two support props which are located adjacent to the tunnel floor and the support arches are joined to one another adjacent to the floor and adjacent to the roof via double-stroke cylinders. This provides the temporary tunnel support in a simple manner with the necessary mobility in the longitudinal and transverse direction with respect to the tunnel. It is true that "walking" tunnel support frames are known (Offenlegungsschrift 25 52 428.1) but these consist of two support frames which are telescoped into one another and the girders of which overlap correspondingly. It is thus impossible to secure small tunnel areas by placing extensions in place using such a "walking" tunnel support.On the contrary, it is necessary to expose the cross-section over its whole circumference, before the girders of the appropriate support frame can be advanced.

Desirably in a support according to the invention, the advancing of the support arches with their support props is facilitated by the fact that each support prop is provided with a floor plate the edges of which are upwardly inclined.

The load on the thrust girders, and on the rock behind them, due to the releasing and setting of the support props, is to a large extent held within limits due to the fact that, as proposed, between the support props and an hydraulic pump (which can be detachably connected to the support), in each case a valve can be provided which can apply a reduced back pressure to the props. This makes it possible to keep the moving support arch and its support props braced between the thrust girders and the floor with a residual force of, for example, 5 t during "walking". This is an additional contribution to the prevention of crosssectional losses.

Compensation for unevenness in the area of the tunnel floor can be achieved by supporting the double-stroke cylinders adjacent to the floor in elongate holes. This simple measure guarantees compensation of the greatest possible extent, which becomes necessary particularly when the temporary tunnel support is moved in from the area which is still supported into the area to be reripped. The same applies when the temporary tunnel support is moved at the end of the holing zone into the undamaged area which is still supported.

According to a further embodiment of the invention, provision is made for the centre support prop to be associated with a compensating cylinder which acts vertically and is coupled to the respective doubie-stroke cylinder which is adjacent to the floor. This makes it possible to hold the two lower double-stroke cylinders in the horizontal position favourable for an advance over an uneven floor.

Suitably provision is made for the thrust girders to be constructed as a pair of I-girders which are joined to one another e.g. via a cover plate. Not only can such girders be produced relatively inexpensively but, in addition, they are distinguished by great stability. They are particularly suitable for the intended work, because the forces to be absorbed are to be expected in the direction of the webs of the Isections. The cover plates serve to join the Isections and, at the same time, provide a large girder surface for contacting the roof/wall of the tunnel.

The advance cylinders can be arranged centrally between the I-girders of the pair. In this way they are well protected and are located in the optimum position for the forces to be transmitted by them.

The greatest forces to be transmitted by the thrust girders are to be expected from the roof.

For this reason, and to save material and costs, provision may be made for the thrust girders in the area of the roof to be formed of two I-girders and, in the area of the side of the tunnel, to be formed of two groups of two I-girders each pair having a cover plate. With this arrangement, the thrust girders will be about twice as wide in the area of the tunnel sides compared to those in the area of the tunnel roof, and this saves a considerable number of advance cylinders.

The advance girders are arranged around the outer edges of the support arches. Proper guidance of the girders as they slide over the arches can be guaranteed by providing the support arches with T-shaped projections which are arranged on the outside and are spaced-apart over the circumference thereof, the flanges of the said projections overlying in each case inner flanges of the thrust girders. The T-shaped projections are suitably arranged in such a manner that in each case at least the side of one I-section beam is supported.

New support arches for the tunnel can be installed underneath the mobile roof. In order to facilitate and speed up the work, provision can be made to support an installation aid from one or more of the support arches. This makes a separate support base for the installation aid superfluous and, also guarantees that the installation aid is always to hand when needed.

The mounts for supporting such an installation aid can be such that it hardly reduces the crosssection available within the support, when not in use, so that work taking place within the support is not impeded by it.

Also provision may be made for a work platform which can be hinged to a support arch which may include a swivel joint. The work platform can then also be swung out of the tunnel cross-section if it is not required for current work.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a diagrammatic front view of a temporary tunnel support in accordance with the invention constructed as a support frame, Figure 2 represents a longitudinal section through the support of Figure 1, Figure 3 is an enlarged section through thrust girders in the area of the tunnel roof of the support of Figure 1, and Figure 4 is a section also on an enlarged scale through thrust girders in the area of the tunnel side of the support of Figure 1.

The temporary tunnel support shown in Figures 1 and 2, acts as a support and setting device and is constructed in the form of a support frame generally designated 1. The support frame 1 comprises three support arches 2--4 which span the tunnel, each arch being supported at its lower ends by a pair of support props 6 and 9 in the case of arch 3, and 5 and 7 in the case of the arches 2 and 4 (only one of the pair of props being visible in respect of these arches).The three support arches are essentially of identical construction and can be adjusted in their position transverse to the tunnel with the aid of the support props 5-7 and 9 and in the longitudinal direction of the tunnel by means of double-stroke cylinders 1 4 and 1 6 associated with the support props and a double stroke cylinder 1 5 located near the apex of the arch.

In the embodiment shown in the drawings, the support arches 2, 3 and 4 are associated with a total of thirteen thrust girders 20-23. Each thrust girder is provided with its own advance cylinder 25, 26 or 27 controlled by a hand valve (not shown).

As shown particularly in Figures 3 and 4, each thrust girder comprises a pair of I-girders 28 and 29. These I-girders are linked on their outer face by a cover plate 24 and webs, which are not shown. They are slidably supported against Tshaped projections 42, 43 mounted on the outer periphery of the respective one of the support arches 2-4. Flanges 44 of the T-shaped projections 42, 43 in each case project over lower flanges 47 of the I-girders 28,29 which consist of an upper flange 45, a web 46 and the lower flange 47. Because of the greater pressures to be expected from the roof area of the tunnel, the thrust girders in the roof area consist of two Igirders 28, 29 which are joined to one another via the cover plate 24, and by webs which are not shown. In the centre between the I-girders 28, 29 in each case the advance cylinders 26 are arranged.Reduced pressures can be expected in the area of the sides 33 of the tunnel so that here wider thrust girders 21 and 22 can be employed.

In the side regions of the tunnel the thrust girders consist in each case of two groups 40 and 41 of Igirders. As shown particularly in Figure 4, the advance cylinders 25, 27 in the side regions are arranged between the groups 40 and 41. Thus in both roof and side regions, an optimum covering of the advance cylinders 26 and 27 is guaranteed, particularly if the cover plates 24 of the groups 40, 41 in the side regions extend close to one another.

The advance cylinders 26, arranged in the roof region of the tunnel, in each case extend in the longitudinal direction of the tunnel and are disposed in parallel relationship with the thrust girder 23 and in that way guarantee that the imposed forces generated by the cylinders are transmitted to the thrust girders to an optimum degree. Each cylinder 26 is located to extend between a tip 34 of the respective thrust girder 23 and the central support arch 3 (see Figure 2).

As shown in Figure 2, the support arches 2 and 3 and the support props 5 and 6 are arranged in such a manner that the thrust girders 20 and 21 can in each case be moved forward as far as is shown for the thrust girder 23. Only when all the thrust giders have reached this position does it become necessary to move up the support arch 4.

For this movement, the thrust exerted by the support prop 7 is relieved to the extent predetermined by a back-pressure valve and the double-stroke cylinders 1 xi 16 are then simultaneously pressurised to draw in the piston rods (13 in the case of cylinder 14). This causes the support arch 4 with its support prop 7 to advance towards the other two support arches 2 and 3, with its floor plate 10 dragging over the tunnel floor 30. After the arch 4 has been fixed in its new position, the support arch 2 and its support prop 5 can be advanced by re-extending the cylinders 14-16.

During the advancing (or "walking") operation, different load conditions arise which are governed by the fact that two of the support arches 2-4 always remain actively set and that only the third support arch in each case "walks" forward or backward.

During "walking" the arch to be moved is braced with a residual force (e.g. of the order of 5 t) between the thrust girders 20-23 and the tunnel floor 30. The residual force is obtained by means of the back-pressure valve previously mentioned. Maintaining some residual force on the moving arch reliably prevents any collapse of the support during "walking".

It is the three double-stroke cylinders 14-1 6 which are employed for the "walking" process.

The double-stroke cylinders 14, 1 6 each respectively join the three support props on one side of the tunnel together; the cylinder 1 5 links the arches together in the region of the girder element 60 at the roof of the tunnel. The doublestroke cylinders 14 and 16 are supported via transverse members 1 8 located in elongate holes 19 in the respective support props. Supporting the two lower cylinders in this manner provides the necessary mobility when the appropriate support props are re!ieved. In addition, adequate compensation is provided for the inevitable variations in the level of the tunnel floor. A compensating cylinder 1 7 is provided on each side of the tunnel to ensure that the double-stroke cylinder (14 or 16) maintains an optimum horizontal position even in the presence of unevenness.

The floor plates 10 have upwardly inclined edges 11, 12 to facilitate the advance of the support props by avoiding the plates becoming hooked against any unevenness of the tunnel floor. The required pressure for the support props 5-7 and 9 and for the remaining hydraulic consumers in the support 1 is generated via a pump (not shown) which can be detachably connected to the support frame 1. As the pressure fluid, an oil-in-water emulsion can be used. The nominal load for all six support props is 7,200 KN (720 t) at a piston diameter of 180 mm. Thus the temporary tunnel support supplies itself and can be operated independently of any other equipment.

Work on the tunnel can be done by hand, for example with a mechanical pick or by use of a suitable releasing machine. After the tunnel roof 31 and the tunnel sides 33 have been exposed, the respective thrust girder 20 to 23 is actuated via the appropriate hand valve. Since each thrust girder 20 to 23 is associated with its own advance cylinder 25 to 27, even a relatively small exposed area of the tunnel can be secured against collapse by bringing up the appropriate thrust girder(s) or by an appropriate placing of supporting extensions with the aid of one or more thrust girder(s). This safely prevents the roof and/or sides of the tunnel from spilling out.

Each support arch 2, 3 and 4 is composed of two side arches 61, 62 and a central girder element 60. These are firmly joined together as shown in Figure 1. On each side arch 61 oron its associated support prop 9, mounts 35 are provided for mounting an installation aid generally designated 36. The installation aid 36 simplifies the insertion of the support arches from the rear part, that is out of the secured area. Provision of the aid 36 ensures an accident-free safe work space both for releasing operations and for supporting operations. The installation aid 36 comprises a cantilever 37, at the tip of which is provided a claw 38 for receiving a support arch. A swivel shaft 39 permits the aid 36 to turn in the tunnel and a lift cylinder 51 permits the cantilever 37 to be raised or lowered.The installation aid, which projects into the tunnel space 32 when in use, can be folded back and fixed to the appropriate support arch 2 to 4 when not in use in such a manner that, in practice, is does not lead to any substantial reduction in available crosssectional space within the support 1.

Work platforms 55 and 56 can be provided and are constructed to be foldable via hinges 57. Such work platforms 55, 56 can be of particular assistance in simplifying the application of bracing between the individual arches. It is possible to construct the work platforms 55, 56 in such a manner that they can be folded, va a swivel joint, to lie flush with the appropriate side arch 62.

As shown in Figure 2, the support 1 can be utilized to advantage in such a manner that in each case first the cross-section in the area of the tunnel roof 31 is re-ripped and the thrust girders 23 are there advanced correspondingly. This uncovers the tunnel roof 31 in the rear area, where it can rapidly be secured with a girder and appropriate bracing materials. When this has been completed, the thrust girders 20 and 22 covering the side regions 33 of the tunnel can be advanced and the exposed side regions secured correspondingly by props and bracing materials.

Claims

1. A temporary tunnel support for holing operations in tunnels of underground mines, comprising thrust girders which extend in the longitudinal direction of the tunnel and support frames which carry them, each thrust girder, being associated with an advance cylinder and projecting past the respective support frame both at the front and at the rear, the support frame being formed of at least three support arches which are adapted to be moved independently of one another in the longitudinal direction of the tunnel and/or transversely with respect to the tunnel.

2. A temporary tunnel support according to claim 1, in which each support arch is associated with two support props which are located adjacent to the tunnel floor, the support arches being joined to one another adjacent to the floor and adjacent to the roof via double-stroke cylinders.

3. A temporary tunnel support according to claim 1 or claim 2, in which each support prop is provided with a floor plate having upwardly inclined edges.

4. A temporary tunnel support according to any preceding claim in which between the support props and an hydraulic pump therefor, a valve is provided which can apply a reduced back pressure to the props.

5. A temporary tunnel support according to claim 2, in which the double-stroke cylinders adjacent to the floor are supported in elongate holes.

6. A temporary tunnel support according to claims 1, 2 or 5, in which the support props of the central arch are each associated with a compensating cylinder which acts vertically and is coupled to the respective double-stroke cylinder which is adjacent to the floor.

7. A temporary tunnel support according to any preceding claim, in which the thrust girders are constructed as a pair of I-girders which are joined to one another via a cover plate.

8. A temporary tunnel support according to claim 7, in which the advance cylinders are arranged between the Girders.

9. A temporary tunnel support according to claim 7 or 8, in which the thrust girders in the roof area of the tunnel are formed of two I-girders and, in the area of the tunnel sides, are formed of two groups of pairs of I-girders each pair having a cover plate.

10. A temporary tunnel support according to claims 7, 8 or 9 in which the support arches are provided with T-shaped projections which are arranged on the outside and are spaced-apart over the circumference thereof, the flanges of the said projections overlying in each case inner flanges of the thrust girders.

11. A temporary tunnel support according to any preceding claim, in which at least one support arch mounts an installation aid.

12. A temporary tunnel support according to any preceding claim in which a work platform is hingedly mounted on a support arch.

1 3. A temporary tunnel support substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.