GB2327680A

GB2327680A - Filler composition and method and device for filling a cable conduit

Info

Publication number: GB2327680A
Application number: GB9813638A
Authority: GB
Inventors: Ernst Mayr; Guenter Schroeder; Guenther Weber; Dieter Kreutz; Guenter Einsle; Heinz Diermeier
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1997-06-24
Filing date: 1998-06-24
Publication date: 1999-02-03
Also published as: GB9813638D0; DE19726880A1; FR2764996A1

Abstract

A filler composition for back filling an underground channel or conduit for optical fibres or cables, comprises a water-repellant and sealing base material such as bitumen, the composition also containing a flexible granular material such as rubber, the latter enhancing the mechanical protection of the cables. Preferably the rubber is produced by granulating old vehicle tyres and has a particle size of 0.5 - 3 mm. Alternatively the flexible material can be a granulated plastics such as a silicone. the granular material may be dyed to provide a warning during excavation. the invention also comprises a conduit containing a cable and filled with the composition and a method of filling such a conduit using the composition. A filling device for filling a channel according to the method comprises filling funnel for receiving the material, a filling slit at the base of the funnel, a spiral stirrer in the funnel, a conveyor spiral above the filling slit, a guide unit for lowering into the channel to be filled and a pressing unit behind the filling slit for pressing the filler into the channel.

Description

2327680 Filler and method for filling a conduit The invention relates to a

filler for filling a channel for optical fibres and cables that has been made in a hard laying foundation, such as a road.

Methods for laying cables having optical or electrical information conductors in a hard laying foundation are known. In this specification the term.,,cable,, is used as a general term, including both optical fibres and electrical cables.

optical-fibre cables, such as micro-cables for example which consist of a tube with optical fibres arranged loosely therein, are most suitable for this. The respective cable is placed in the laying channel and the channel is then filled with filling material in such a way that a complete mechanical protection and water-tightness is again given. In previous methods, an elastic, impact-resistant covering profile, which is difficult to cut through by mechanical interventions from the outside, is, after the insertion of a microcable into the laying channel, laid in the longitudinal direction of the mini-cable or micro-cable, so that the channel is filled. Furthermore, methods are known in which bituminous masses are used in order to fill the channel after the insertion of a cable, with a protective element, for example made of sponge rubber, being placed over the cable first of.all.

According to a first aspect of the invention there is provided a filler based on a water-repellant and sealing base material for filling a channel for optical fibres or cables that has been made in a hard laying foundation, wherein in addition to the base material the filler also contains a granular material having flexible properties.

The invention provides a filler for sealing a laying channel after the insertion of a cable, which filler on the one hand has elastic properties and on the other hand forms a cover for the laying channel that can withstand mechanical stress and is longitudinally watertight or absorbs little water. The filler is improved in that a granular material having flexible properties is added to the base material.

In comparison with the prior art, considerable advantages result in the case of the filler in accordance with the invention, with regard to the flexibility, the temperature resistance, and the resistance to fungus and microbes. Apart from this, on the basis of its consistency, the filler in accordance with the invention is sufficiently longitudinally watertight and water-repellant that penetration of water into the filled laying channel hardly takes place. The filler can be made in such a way that the maximum absorbable water content does not result in damage to the closed laying channel. Finally, the filler is easy to process and cheap.

All of these properties may be fulfilled by the filler in accordance with the invention, which filler is preferably produced from bitumen with an admixture of granular material the granular material being elastic, possibly firm, and not water absorbing. A water-repellant material having adhesive properties, as bitumen has for example, may be used as base material.

As a granular material having elastic properties, rubber is particularly suitable for the filler. It is mixed in in the form of particles having an average grain size of 0.5 to 3 mm, Likewise, a floury granular material having an average grain size of < 1 mm can be used, if overall a more homogenous filler is to be used. The rubber granular material is, for example, produced from old tyres (such as used car tyres) and is is still flexible enough even at sub-zero temperatures to allow itself to be compressed if water has seeped in and frozen. Damage to the road surface is avoided as a result. The granular material may also be made of flexible plastics material, such as silicone.

In the case of a non-water-absorbent filler, bituminous sand is preferably used as a base material. Bitumen or a gel-like plastics mass, preferably polyisobutylene, is also particularly suitable as a base material. The mixture ratio between the base material and the granular material is matched to the respective purpose of use or the given ratios of the laying channel. The mixture ratio of granular material: base material preferably amounts to 50 to 70%: 30 to 50%, further preferably to 60: 40 % by volume, respectively.

In the region of the cable, a release agent (1 to 3 % by volume), such as paraffin, may be added to the mixture of base material and granular material in order to be able to ensure a release from the cable in the event of an opening of the channel that may be required later. Apart from this, corresponding mixtures of different base materials, for example polyisobutylene and bitumen, and/or different granular materials can be mixed together, in order to, for example, achieve the most favourable match to the surrounding materials. The release agent can, however, also already be deposited on the cable sheath or on the conduit of a microcable, and the admixtures in the filler can then be omitted.

All in all, the flexible granular material in the base material forms the basis for the flexible consistency of the filler and furthermore forms spacers to the cable which has been laid, for example also between two metal conduits of cables. With an appropriate concentration of flexible granular is material, for example, it is possible to dispense with a polyethylene insulating sheath for the conduit of the cable.

The elastic granular material which is used can also be dyed with a warning colour, for example yellow, so that it can be easily recognised as a marker when reopening the laying channel. If the dyed granular material is used only in the deeper parts of the laying channel, it can at the same time serve as a warning that during the reopening, the vicinity of the cable which has been put in has been reached. Another type of marking would be, for example, the insertion of a dyed warning strip, as is generally used in the known laying methods.

The base material or granular material is matched to the cable or optical fibres. If there is a PEsheathed copper conduit with optical fibres, this will preferably be laid in bituminous sand and covered with bituminous sand (for example 10 mm high), then the channel is filled with a bitumen mixture and sealed with bitumen.

Micro-cable can also be laid and coated with bituminous sand. Instead of the bituminous sand, fine rubber granular material can also be used, or both materials combined.

The same procedure can be used if a dielectric cable is used instead of the micro-cable, heat insulation with respect to the hot bitumen here being a matter of priority. Examples of such cables are the 11AD-Lasch11 cable or a maxibundle of optical fibres or strips. It is here advantageous for the filler to be made flexible. Alternatively, the filler can also be used when laying electric cables.

The base material, for example bitumen, and the respective granular material can be made flexible in such a way that even bare information conductors, for is example large uninsulated optical-fibre bundles, can be put in without further sheath protection. In this case, the optical fibres or cables are accommodated only in a filled rigid plastics core which is embedded in the filler. With this type of use, the optical fibres or optical-fibre strips may be dyed appropriately and the base material may be mixed with paraf fin. This result of this is that in the event of a fault, a good separability of the optical fibres or optical-fibre strips from the base material, for example the bitumen. is given, for easy identification as a result of the dying. Instead of the bitumen, another suitable plastics material or a gel-like mass, as used in the known core filler LA444, for example, can be used, if only optical fibres without a core cover are to be used.

In the method according to a second aspect of the invention for filling a laying channel (conduit) which has been made in a hard laying foundation, for example a road topping, filling material in the form of filler in accordance with the first aspect of the invention is put in after the insertion of the cable, in such a way that the cable is surrounded, and then further filling material is poured in up to the upper edge of the channel. This method can be carried out using a filling device in accordance with a third aspect the invention. The filler goes from a filling funnel through a filling slit into the open laying channel, into which the cable has already been placed. In this method, the individual functional units are installed on a carriage which travels along over the laying channel. In this connection, a guide unit engages in the open laying channel before the filling and guides the filling device. After the filling of the laying channel, the filler is then pressed down. The cable is preferably a micro-cable.

The method, with the aid of the filler in accordance with the invention, provides a reliable longitudinal water seal of the laying channel. Any moisture which is absorbed does not result in damage to the laying channel.

Specific embodiments of the invention will now be descrived, purely by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows the laying of micro-cables in a channel of a hard laying foundation; Figure 2 shows the laying of an optical fibre strip in the channel of a hard laying foundation; Figure 3 shows a filling device for filling a channel.

Figure 1 shows a channel 1 which has been cut into a hard laying foundation 2 and has a depth 7 of approximately 40 to 90 mm for the laying of cables, for example micro-cables 3. Here, for example, two microcables 3, each comprising a tube and optical fibres 4 placed loosely therein, are laid in the channel base of the channel 1. In this exemplary embodiment, the channel is filled up again with two layers 5 and 6 after the insertion of the micro-cable 3, with the lower layer 5 being approximately 40 to 50 mm thick and consisting of the filler 8 in accordance with the invention. Here, the base material, for example bitumen, is mixed with a granular material 11 having elastic properties, with paraffin being added as well if appropriate. The layer 6 of filling material on top of this again consists of a base material 9, for example bitumen, into which, however, has been mixed grit 10, so that this layer is matched to the mechanical properties of the hard laying foundation 2, for example the asphalt of a road. This upper layer 6 fills the channel 1 above the layer 5 almost to the upper edge; a seal with pure bitumen seals the channel in a watertight manner.

Figure 2 shows an embodiment for the laying of an optical-fibre strip 15, which is embedded directly in the layer 14 of filler in accordance with the invention. This layer 14 has a thickness of 15 mm for instance, and consists, for example, of bitumen as base material and a floury granular material, for example made of rubber powder. A thickness of approximately 40 mm of a further layer 13 of filler in accordance with the invention is arranged on top of this, which layer 13 contains fine bitumen as base material and a granular material made of rubber particles. Above this layer 13, the channel 1 is filled up to the edge of the laying foundation 2 with a layer of filling material being coarse bitumen to which grit (gravel) is added. If appropriate, the channel is also sealed. A robust filled conduit thereby results.

Figure 3 shows a filling device 16 which is suitable for the method for filling a channel with filler in accordance with the invention. This filling device 16 comprises a filling funnel 17, into which the filling material 18 to be inserted is poured. In order to ensure an even mixture, the filling material 18 is mixed with the aid of a spiral stirrer 24, which is, for example, driven by a motor 23. The base portion of the filling funnel 17 has a filling slit 19, through which the filling material 18 is forced with the aid of a conveyor spiral 26, which is driven by a motor 25, into the still open channel 1 of a hard laying foundation 2, for example of a road topping. After the channel 1 has been filled, the filling material 18 which has been put in is pressed down evenly with the aid of a pressing unit 28 which runs along behind, for example a spring-mounted roller. The whole filling device 16, which is, for example, mounted on a carriage 20 having its own drive 21,.is guided by a preceding guide unit 22, for example a guide nose which is connected to the front axle of the carriage 20. Furthermore, the filling device 16 can be provided with a fullness indicator 27, which indicates by means of a warning lamp 29 that the filling funnel 17 needs to be topped up with filler 18. For reasons of clarity, the cable, preferably micro-cable consisting of a tube and optical fibres guided loosely therein, which cable is put in before the filling, is not shown.

Claims

1. A filler based on a water-repellantand sealing base material for filling a channel for optical fibres or cables that has been made in a hard laying foundation, wherein in addition to the base material the filler also contains a granular material having flexible properties.

2. A filler according to claim 1, wherein the particles of the granular material have an average grain size of 0.5 to 3 mm.

3. A filler according to claim 1, wherein the granular material is floury, with particles having a grain size of less than 1 mm.

4. A filler according to any preceding claim, wherein the base material is bitumen or bituminous sand.

5. A filler according to any of claims 1 to 3, wherein the base material is a gel-like plastics mass, preferably polyisobutylene and bitumen.

6. A filler according to any preceding claim, wherein the granular material is produced from rubber.

7. A filler according to any of claims 1 to 5, wherein the granular material is produced from a flexible plastic.

8. A filler according to claim 7, wherein the flexible plastic is a silicone.

9. A filler according to any of claims 1 to 6, wherein the granular material is produced from used rubber goods.

10. A filler according to claim 9, wherein the used rubber goods are old tyres from cars or other vehicles.

11. A filler according to one of the preceding claims, wherein the granular material is dyed with a warning colour.

12. A filler according to any preceding claim, wherein the filler comprises different base materials and/or different granular materials mixed together.

13. A filler according to any preceding claim, wherein a release agent, preferably paraffin, is added to the mixture of base material and granular material in an amount of 1 to 3 % by volume.

14. A filler according to any preceding claim, wherein the mixture ratio of granular material: bade material amounts to 50 to 70: 50 to 30 % by volume respectively.

15. A conduit comprising:

a channel; a cable laid in the channel; filling material filled to the top of the channel wherein the filling material surrounding the cable is filler according to any preceding claim.

16. A conduit according to claim 15, wherein the filling material is arranged in one continuous layer of filler.

17. A conduit according to claim 15, wherein the filling material is arranged in a plurality of layers, with the different layers including granular materials having particles of different grain sizes.

18. A conduit according to claim 17, wherein grit is added in the uppermost layer of filling material.

19. A conduit according to claim 18, wherein the uppermost layer of filling material is coarse bitumen and grit.

20. A conduit according to claim 19 wherein the uppermost layer is asphalt.

21. A conduit according to any of claims 17 to 20, wherein the grain size of the particles of the granular material is smallest in the lowest layer and largest in the uppermost layer.

22. A conduit according to claim 21, characterised in that the filling material is arranged in three layers, one on top of the other, with the lowest layer containing floury granular material, the middle layer containing coarse grained granular material and the uppermost layer containing grit.

23. A conduit according any of claims 15 to 21, wherein the cable is an optical fibre cable.

24. A conduit according to any of claims 15 to 23, wherein the top of the filling material is coveted with a seal.

25. A conduit according to claim 24, wherein the seal is bitumen.

26. A conduit according to any of claims 15 to 24, wherein the channel is laid in a hard laying formulation.

27. A method for filling a channel to obtain a conduit, wherein the cable is inserted in the channel, filling material being filler according to any of claims 1 to 14 is laid into the channel with the aid of a filling device in such a way that the cable which has been put in is surrounded, the channel is filled with filling material up to the upper edge of the channel, and the filling device is guided in the channel during the filling by a guide unit.

28. A method according to claim 27, characterised in that the filling material is put in in one continuous layer of filler.

29. A method according to claim 27, characterised in that the filling material is put in in a plurality of layers, one on top of the other.

30. A method according to claim 29, characterised in that a lower layer of filling material containing fine granular material is put in until the cable is completely covered, and in that at least one further layer containing coarse granular material is put in on is be f illed, top of this.

31. A method according to one of claims 29 or 30, characterised in that an upper layer of filling material containing admixtures of grit is deposited over the layer of filler with granular material.

32. A filling device for filling a channel according to the method of claims 26 to 30, comprising a filling funnel for receiving the filling material, a filling slit on the base of the filling funnel, a spiral stirrer in the filling funnel, a conveyor spiral above the filling slit, a guide unit for lowering into the channel to and a pressing unit for pressing in the filler behind the filling slit.

33. A filler according to any of claims 1 to 14 substantially as herein described with reference to and as shown in Figure 1, Figure 2 or Figure 3 of the accompanying drawings.

34. A conduit substantially as herein described with reference to and as shown in Figure 1 or Figure 2 of the accompanying drawings.

35. A filling machine substantially as herein described with reference to and as shown in Fig. 3 of the accompanying drawings.