GB2495503A

GB2495503A - Method and apparatus for the installation of cables or pipes in tunnels

Info

Publication number: GB2495503A
Application number: GB1117509.8A
Authority: GB
Inventors: Dave Thomson; Christopher Midson
Original assignee: THOMSON ENGINEERING DESIGN Ltd; Balfour Beatty PLC
Current assignee: THOMSON ENGINEERING DESIGN Ltd; Balfour Beatty PLC
Priority date: 2011-10-11
Filing date: 2011-10-11
Publication date: 2013-04-17
Also published as: GB201117509D0

Abstract

The invention relates to the installation of cables or pipes in tunnels, and in particular relates to the suspension arrangement for suspending the cable or pipe from blocks 10, 50, 54 spaced along a support rail 40, prior to fixing it to a ceiling. The suspension block has an upper roller arrangement (14, 16, Fig 1) for suspending the block from an upper rail and a lower roller arrangement (22, Fig 1) for suspending the block from a lower rail. The upper roller arrangement is controllable between engaged and disengaged configurations, so that the block 50 can be released from the upper rail 40 to allow another block 10 to pass, the block 50 running onto a lower rail 44 carried by the block 10. The upper rollers may be made to disengage by movement of a cam (28, Fig 4) which is operated by the front end 52 of lower rail 44. This enables cable loading into a tunnel and cable installation to the tunnel wall to be carried out in parallel.

Description

METHOD AND APPARATUS FOR THE INSTALLATION OF CABLES OR PIPES

IN TUNNELS

Field of the invention

This invention relates to the installation of cables or pipes in tunnels (or other ducts), and relates particularly to a suspension block design forming part of an installation system.

The installation of cables in tunnels presents many different problems as a result of the restricted space (both within the tunnel and the access to the tunnel) and the significant weight of the cables. The cables need to be secured at regular intervals, and an amount of sag needs to be provided between the securing points, to allow for expansion of the cable.

The tunnel typically has a single supporting rail at the top, which is used to feed cables into the tunnel using a train of suspension blocks. Once a cable has been fed into the tunnel, it is taken off the suspension blocks one at a time and mounted to the tunnel wall. Thus, there is a two stage installation process. The train of suspension blocks is then returned to the tunnel opening, able to be used for another cable to be installed. Multiple cables may be installed in sequence.

Cables are normally laid in sets of three, one for each electrical phase, running parallel one above the other at different levels. Being very expensive, the cable is supplied cut to length on drums with each drum carrying a single cable designated for a specific location within the tunnel. Thus, the cable in the tunnel is formed as a series of connected sections.

Normally all the cables on a single level are laid in sequence, although this is not a hard and fast rule, beginning at the end of the tunnel most remote from the point where the cables are fed into the tunnel (the delivery paint) and working back towards the delivery point.

A towing tractor is used to pull the cable into position, and a cable fixing unit is used to dismount the cable and fix the cable to the tunnel wall, for example onto spaced mounting brackets.

It would be desirable to be able to feed one cable into the tunnel while another is being mounted to the tunnel wall. However, this is not currently possible. In particular, there is generally only one support beam in the tunnel, so that only one series of suspension blocks can be fed in and out of the tunnel at a time.

The invention relates to an apparatus and method for addressing this problem so that pulling of one cable and installation of another can be performed concurrently.

Summary of the invention

According to the invention, there is provided a suspension block for suspending a cable or pipe from a rail, comprising: an upper roller arrangement for suspending the block from an upper rail with the upper roller arrangement seated on the upper rail; and a lower roller arrangement for suspending the block from a lower rail with the lower roller arrangement seated on the lower rail, wherein the upper roller arrangement is controllable between engaged and disengaged configurations, wherein in the disengaged configuration, the block is released from the upper rail, and wherein the block comprises a release mechanism for controlling the upper roller arrangement to the disengaged configuration when a lower rail is present.

This suspension block enables another suspension block on an upper rail to be moved out of the way and transferred to a lower rail, when a cable or pipe is being fed into the tunnel suspended from the upper rail. The suspension blocks which are in the way may relate to a cable being installed, which has already been released from those suspension blocks, whereas the upper rail is being used to feed a new cable. When the leading suspension block for the cable being fed in reaches another one on the main rail, essentially two rails are formed. One can be used to pull the new cable in one direction with one train of suspension blocks, and the other can be used to pull the train of blocks which have already been unloaded in the opposite direction. The two trains of blocks can thus pass each other.

The upper roller arrangement can comprise a front pair of rollers which face each other and a back pair of rollers which face each other, wherein in the engaged configuration, the rollers of the upper roller arrangement surround a lower flange of the upper rail, wherein in the disengaged configuration the pairs of rollers are opened apart wider than the lower flange width. By opening apart the pairs of rollers, the suspension block is able to drop off the upper rail onto the lower rail where it is already supported by the lower roller arrangement.

The pairs of rollers of the upper roller arrangement are by default in the engaged configuration, so that in the absence of a second rail, they are used to suspend a cable or pipe from the main rail. The release mechanism can comprise a cam which is engaged by the lower rail to urge the pairs of rollers of the upper roller arrangement apart.

The lower roller arrangement can also comprise a front pair of rollers which face each other and a back pair of rollers which face each other, wherein the rollers surround a lower flange of the lower rail when the lower rail is present.

A cable or pipe harness is suspended from the block, and this is used to hold the cable or pipe as a train of suspension blocks is advanced. The suspension block may also comprise a rail mounting point for mounting a rail additional to the rail from which the block is suspended. This additional rail is the lower rail to which the suspension blocks which are in the way can be diverted.

The invention also provides a cable or pipe installation system, comprising: a plurality of suspension blocks of the invention; an upper rail for supporting the suspension blocks using their upper roller arrangements; a lower rail for attachment to mounting points of the suspension blocks, wherein the lower rail is for disengaging other suspension blocks from the upper rail so that they are transferred to the lower rail.

When feeding a cable or pipe along the upper rail, a lower rail is also pulled into place. This is then used to transfer suspension blocks on the upper rail which are being pulled in the opposite direction, so that two trains of suspension blocks can pass each other.

The upper rail and the lower rail preferably each comprise an upright web and a base flange on each side of the web, wherein the roller arrangements are for sitting on the base flange on each side of the upright web.

The invention also provides a method of installing a cable or pipe in a tunnel comprising: feeding a first cable or pipe along an upper rail using a first series of suspension blocks; removing the first cable or pipe from the suspension blocks and mounting the first cable in the tunnel; feeding a second cable or pipe along the upper rail using a second series of suspension blocks, wherein the suspension blocks carry a lower rail; when a forward end of the second series of suspension blocks on the upper rail reaches a suspension block of the first series, transferring the suspension block of the first series off the upper rail to the lower rail of the second series of suspension blocks, by disengaging the suspension block of the first series from the upper rail by releasing a first roller arrangement of the suspension block of the first series to allow it to drop to the second rail of the second series of suspension blocks.

This method enables simultaneous loading of one cable or pipe into the tunnel and installation of a previously loaded cable or pipe.

The suspension blocks can each comprise an upper roller arrangement for suspending the block from the upper rail; and a lower roller arrangement for suspending the block from the lower rail, and wherein the upper roller arrangement is controllable between engaged and disengaged configurations and the releasing of the first roller arrangement is implemented by the second rail engaging with the another suspension block.

Brief description of the drawings

An example of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a suspension block of the invention in perspective view; Figure 2 shows the suspension block of Figure 1 in front view; Figure 2 shows the suspension block of Figure 1 in front view with the top rollers closed; Figure 3 shows the suspension block of Figure 1 in front view with the top rollers open; Figure 4 shows the suspension block of Figure 1 from above with the top rollers closed; Figure 5 shows the suspension block of Figure 1 from above with the top rollers open; Figure 6 shows a first stage of a cable installation method of the invention; Figure 7 shows a next stage of the cable installation method of the invention; Figure 8 shows a next stage of the cable installation method of the invention; Figure 9 shows the engagement of the lower rail as in Figure 8 in more detail; Figure 10 shows a next stage of the cable installation method of the invention; Figure 11 shows a next stage of the cable installation method of the invention; Figure 12 shows the arrangement in end view; and Figure 13 is used to explain the installation method.

Detailed description

The invention relates to the installation of cables or pipes in tunnels, and in particular relates to the suspension arrangement for suspending the cable or pipe from blocks spaced along a support rail. The description below is for the preferred use of the apparatus for installing electrical cables.

The invention provides a suspension block having an upper roller arrangement for suspending the block from an upper rail and a lower roller arrangement for suspending the block from a lower rail. The upper roller arrangement is controllable between engaged and disengaged configurations, so that the block can be released from the upper rail to allow another block to pass. This enables cable loading into a tunnel and cable installation to the tunnel wall to be carried out in parallel.

Figure 1 shows a suspension block 10 of the invention in perspective view; The suspension block 10 is for suspending a cable or pipe from a rail, which is typically fixed to the top wall (or roof) of a tunnel. The block has an upper roller arrangement for suspending the block from the rail with the upper roller arrangement seated on the rail.

The upper roller arrangement comprises a front pair of rollers 14 which face each other and a back pair of rollers 16 which face each other. The rollers are spaced apart so that they sit over a lower flange of the rail and are positioned on each side of a vertical web of the rail. The block can be pulled along the rail, with the rollers driving along the lower flange.

The pairs of rollers 14, 16 of the upper roller arrangement are normally in a position where they are close together, in particular closer together than the width of the lower flange.

A cable or pipe harness 18 is suspended from the block. Furthermore, there is a rail mounting point 20 for mounting a rail additional to the rail from which the block is suspended.

The block also has a lower roller arrangement 22. This is used to drive the block along a different, lower, rail when required, as is explained below. The lower roller arrangement 22 also has a front pair of rollers 24 which face each other and a back pair of rollers 26 which face each other. These rollers surround a lower flange of the lower rail when the lower rail is present.

The suspension block can be transferred from an upper rail to a lower rail, in particular to allow the blocks to pass each other. For this purpose, the pairs 14, 16 of upper rollers can be opened apart to a disengaged configuration. The pairs of rollers are then opened apart wider than the lower flange width of the upper rail so that the block drops off the upper rail. As will be shown below, the block is already supported by the lower rollers engaging with the lower rail.

The block 10 comprises a release mechanism for controlling the upper roller arrangement to the disengaged configuration when a lower rail is present. For this purpose, the upper rollers are mounted on hinged arms which can open and close (with the hinge axis parallel to the cable axis). Thus, the upper rollers can clamp over the rail flange in a jaw-like manner.

In a preferred design, a cam forces the arms apart at the base, and this holds the jaws closed. If the cam is rotated and therefore out of the way of the base parts of the jaws, the jaws are spring biased to open. The cam can be spring biased into the position in which the jaws are closed, so that the natural position is for the jaws to be closed even though they are spring biased open. There are of course many other ways to control the opening and closing of the jaws.

Figure 2 shows the suspension block of Figure 1 in front view with the top rollers 14, 16 ctosed. The cam 28 can be seen in Figure 2, which holds the base of the jaws apart. The jaws hinge about the pins 30, which can include torsional springs to provide the required opening force.

Figure 3 shows the suspension block of Figure 1 in front view with the top rollers 14, 16 open. As shown, the cam 28 has been turned to be narrower in front view to allow the jaws to open.

The cam 28 thus functions as a release mechanism, and this is engaged by a lower rail to cause the pairs of rollers of the upper roller arrangement to move apart.

Figure 4 shows the suspension block of Figure 1 from above with the top rollers closed. The cam 28 can be seen more clearly in its wide setting, pushing the jaws apart at their base and therefore together at their tops.

Figure 5 shows the suspension block of Figure 1 from above with the top rollers open. The cam 28 can be seen more clearly in its narrow setting, allowing the jaws to spring open.

Figure 6 shows a first stage of a cable installation method of the invention.

A series of blocks 10 form a train which is pulled along the upper rail 40 mounted at the top of the tunnel wall. A cable 42 is suspended from the harness loops. A lower rail 44 is also attached to the rail mounting points.

As will be explained below, the advancing cable can reach other suspension blocks 50 as shown in Figure 7. These will have had their cable removed, but they are in the way of the advancement of the cable 42. The additional lower rail 44 has a front end 52 which is specifically designed to engage with the cam 28 and when the suspension block 50 is made to slide over the front end 52, the cam is turned, releasing the top rollers. The block is released from the upper rail 40 and is instead supported by the lower rail 44.

Figure 8 shows the initial engagement (upper rollers closed) and Figure 9 shows the situation more clearly a few moments later with the upper rollers open.

Figure 10 shows that after further advancing of the cable, the suspension block 50 has travelled along the lower rail 44 and the front end 52 of the lower rail is approaching the next suspension block 54.

The additional loading on the upper rail 40 is only the suspension blocks and rail, and this is much less than the cable weight.

Figure 11 shows the arrangement after two blocks have been fed onto the lower rail 44 and the next block 55 is approached.

The suspension blocks 50,54,55 also carry another rail 56. This rail 56 is not used in the installation of the cable shown. However, the two trains of suspension blocks are used in sequence, so the additional rail of the suspension blocks 50,54,55 will be part of the process in the next cycle and will form the rail 44.

The additional rails comprise hinged sections so that they can bend when the suspension blocks are diverted, as shown in the figures.

Figure 12 shows the arrangement of Figure 11 in end view. It shows more clearly the I-beam cross section of the upper rail 40, and the upright web and base flange of the lower rails 44, 56.

Figure 13 is used to explain the installation method. The figure shows a tunnel 60 with the main upper rail 40 at the top. The tunnel typically has a diameter of 3m (although 4m is equally common). The cable supports are bolted to the tunnel wall, for example spaced 7.2m along the tunnel length. The cables are mounted with cable cleats, and the cables are desired to have a controlled amount of sag, to permit expansion. The sag should be the same for all three cables of a three phase system so that short circuit straps can be fitted mid-way between the support locations.

The cable can for example comprise a high power electric 400kV cable. The cables can be provided in lengths of the order of 1km, with diameter up to 140mm.

In Figure 13A, a tug 62 has pulled the first cable 63 along the rail 40 using spaced suspension blocks. These blocks are as described above. The dotted line represents the lower rail attached to the mounting points. It is dotted because it plays no part in the installation of the first two cables (as shown in Figure 13) and has therefore been simplified to make the figure clearer.

Once the cable 63 has been delivered to the point at which it is to be installed, the tug 62 is immediately disconnected from the cable train and returns at once to load a second cable onto a second train.

Whilst the tug 62 is being attached to the second cable train and the second train of suspension blocks is being loaded with the second cable 66, the installation machine works 64 its way along the first cable train installing the first cable 63 onto the wall brackets. The installation machine begins at the end of the cable most remote from the delivery point and moves towards the delivery point. Assuming that the first cable 63 was towed into the tunnel in a left to right direction then the installation machine moves right to left when installing. This is shown in Figure 1 3B, which shows the initial stages of the installation of the first cable 63 from the remote end using the installation machine 64. This machine 64 may have been already driven into position before the tug 62 pulled the first cable 63 into position.

The machine 64 lifts the cable from the harnesses and mounts the cable, with a desired amount of sag, at a series of mounting points along the tunnel wall.

Once the first cable 63 is fully installed, the installation machine 64 moves back along the tunnel (left to right) a short way to allow room for the tug 62 to tow the second cable 66 to a position where it can adjoin the end of the first cable.

The tug 62 is now disconnected from the second cable train which it has just delivered. It is then connected to the first (now empty) train of suspension blocks which it tows back to the delivery point ready to be loaded with a third cable.

The tug 62 is able to tow the first train of suspension blocks by means of the suspension block design above. In particular, the top rail 40 in the tunnel is in use in suspending the second cable 66. The trains of suspension blocks are able to pass each other, and the first train of suspension blocks is fed back along the additional lower rail 44 towed by the tug 62. For this reason, the additional lower rail 44 is shown more fully (rather than dotted), because it carries the empty first train of suspension blocks.

The installation machine 64 then installs the second cable 66 and this empties the second cable train, as shown in Figure 13C.

Effectively, the invention allows an empty cable train to leapfrog a loaded one on its way back to the delivery point and, by using two machines -a tug and an installation machine -unproductive time is minimised and output maximised.

In particular, cables can be installed in sequence, but with the cable towing and cable fixing processes performed in parallel. This saves time in the installation of multiple cables.

In the example above, the rollers are spring loaded open with a cam jamming them closed. Of course, the rollers may be spring loaded closed, with the cam forcing them open when engaged by the rail.

In the example above, there is one tug for towing and one for fixing, but the same design of machine can perform both functions.

The above description relates to the installation of electrical cables. However, the same apparatus can be used for pipes for carrying gases or fluids or indeed any pipe-shaped objects.

The jaw design above is only one possible design. Essentially, the suspension block carries a secondary rail, and is designed to transfer blocks from the main rail to the secondary rail when they are encountered on the main rail. Various other mechanical designs can implement this function.

Various modifications will be apparent to those skilled in the art.

Claims

<claim-text>Claims 1. A suspension block for suspending a cable or pipe from a rail, comprising: an upper roller arrangement for suspending the block from an upper rail with the upper roller arrangement seated on the upper rail; and a lower roller arrangement for suspending the block from a lower rail with the lower roller arrangement seated on the lower rail, wherein the upper roller arrangement is controllable between engaged and disengaged configurations, wherein in the disengaged configuration, the block is released from the upper rail, and wherein the block comprises a release mechanism for controlling the upper roller arrangement to the disengaged configurations when a lower rail is present.</claim-text> <claim-text>2. A suspension block as claimed in claim 1, wherein the upper roller arrangement comprises a front pair of rollers which face each other and a back pair of rollers which face each other, wherein in the engaged configuration, the rollers surround a lower flange of the upper rail, wherein in the disengaged configuration the pairs of rollers are opened apart wider than the lower flange width.</claim-text> <claim-text>3. A suspension block as claimed in claim 2, wherein the pairs of rollers of the upper roller arrangement are spring biased into the engaged or disengaged configuration.</claim-text> <claim-text>4. A suspension block as claimed in claim 2 or 3, wherein the release mechanism comprises a cam which is engaged by the lower rail to cause the pairs of rollers of the upper roller arrangement to move apart.</claim-text> <claim-text>5. A suspension block as claimed in any preceding claim, wherein the lower roller arrangement comprises a front pair of rollers which face each other and a back pair of rollers which face each other, wherein the rollers surround a lower flange of the lower rail when the lower rail is present.</claim-text> <claim-text>6. A suspension block as claimed in any preceding claim further comprising a cable or pipe harness suspended from the block.</claim-text> <claim-text>7. A suspension block as claimed in any preceding claim further comprising a rail mounting point for mounting a rail additional to the rail from which the block is suspended.</claim-text> <claim-text>8. A cable or pipe installation system, comprising: a plurality of suspension blocks as claimed in any preceding claim; an upper rail for supporting the suspension blocks using their upper roller arrangements; a lower rail for attachment to mounting points of the suspension blocks, wherein the lower rail is for disengaging other suspension blocks on the upper rail so that they are transferred to the second rail.</claim-text> <claim-text>9. A system as claimed in claim 8, wherein the upper rail and the lower rail each comprises an upright web and a base flange on each side of the web, wherein the roller arrangements are for sifting on the base flange on each side of the upright web.</claim-text> <claim-text>10. A method of installing a cable or pipe in a tunnel comprising: feeding a first cable or pipe along an upper rail using a first series of suspension blocks; removing the first cable or pipe from the suspension blocks and mounting the first cable in the tunnel; feeding a second cable or pipe along the upper rail using a second series of suspension blocks, wherein the suspension blocks carry a lower rail; when a forward end of the second series of suspension blocks on the upper rail reaches a suspension block of the first series on the upper rail, transferring the suspension block of the first series to the lower rail of the second series of suspension blocks, by disengaging the suspension block of the first series from the upper rail by releasing a first roller arrangement of the suspension block of the first series to allow it to drop to the second rail of the second series of suspension blocks.</claim-text> <claim-text>11. A method as claimed in claim 10, wherein the suspension blocks each comprise: an upper roller arrangement for suspending the block from the upper rail; and a lower roller arrangement for suspending the block from the lower rail; and wherein the upper roller arrangement is controllable between engaged and disengaged configurations and wherein the releasing of the first roller arrangement is implemented by the lower rail engaging with the another suspension block.</claim-text> <claim-text>12. A method as claimed in claim 10 or 11, wherein feeding the second cable or pipe along the upper rail takes place at the same time as mounting the first cable or pipe.</claim-text> <claim-text>13. A method as claimed in claim 10, 11 or 12, wherein the feeding of each of the first and second cables is carried out with a same first tug, and the mounting is carried out with an installation machine.</claim-text> <claim-text>14. A method as claimed in claim 13, comprising returning the first series of suspension blocks to the tunnel entrance after the first cable or pipe is installed using the first tug, while the installing machine is used to remove the second cable or pipe from the suspension blocks and mount the second cable or pipe in the tunnel.</claim-text>