GB2468883A

GB2468883A - Method and apparatus for the installation of cables or pipes in tunnels

Info

Publication number: GB2468883A
Application number: GB0905105A
Authority: GB
Inventors: Vaibhav Tyagi
Original assignee: Balfour Beatty PLC
Current assignee: Balfour Beatty PLC
Priority date: 2009-03-25
Filing date: 2009-03-25
Publication date: 2010-09-29
Anticipated expiration: 2029-03-25
Also published as: GB2468883B; GB0905105D0

Abstract

An apparatus for installing cables or pipes in tunnels comprises a motorized vehicle. A cable/pipe positioning arm is at one end of the vehicle, which is controllable to move a cable/pipe from a temporary installation position to a final installation position. A cable/pipe sagging arm is at the other end of the vehicle, which is controllable to apply a desired amount of sagging to a length of cable/pipe between adjacent final installation positions. The apparatus can be driven along the cable/pipe performing the positioning and sagging in a single sequence. The sagging arm enables a controlled degree of sagging to be applied, which can be made uniform for the different sections of cable or pipe.

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).

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 known installation method uses a significant amount of manual handling, and has tensioned bond wires near the operator, which can present a security risk.

Known cable installation methods include so-called hand pulling, nose pulling and bond pulling. Bond pulling is most suitable for long runs of heavy cables.

The invention relates to an apparatus and method for improving the efficiency of the cable installation process.

Summary of the invention

According to the invention, there is provided an apparatus for installing cables or pipes in tunnels, comprising a motorised vehicle having a cable/pipe positioning arm at one end of the vehicle which is controllable to move a cable/pipe from a temporary installation position to a final installation position, and a cable/pipe sagging arm at the other end of the vehicle which is controllable to apply a desired amount of sagging to a length of cable/pipe between adjacent final installation positions.

The invention in this aspect provides an apparatus which can at one end position a cable or pipe into its desired position, and at the other end apply a desired sag before fixing the cable/pipe in position. References below to the cable should be understood to extend to cables, pipes or indeed other elongate members. The apparatus can thus be driven along the cable performing the positioning and sagging in a single sequence. The cable sagging arm enables a controlled degree of sagging to be applied, which can be made uniform for the different sections of cable.

The motorised vehicle can comprise at least three sections which are adapted to be assembled within the tunnel. This enables the sections to be sized for entry into (and out of) an access shaft to the tunnel. A first, central section can comprise a power module, a second section can comprise a first wheeled axle unit and a third section can comprise a second wheeled axle unit. This provides a modular structure which can be assembled in the tunnel.

Each wheeled axle unit can comprise two wheels having rotation axes which can be adjusted to effect a camber change, such that the wheels can be positioned for rolling on a flat surface or for rolling on opposite inclines. This adjustment enables the wheels to be mounted for rolling on the flat surface at the access location, or on the curved surface of the tunnel. The wheels can also be adjusted for different tunnel diameters.

In one example, the central section can comprise a hydraulic arrangement for coupling the sections together. In another example, the apparatus can further comprising a set of jacks for attachment to a section for controlling the raising and lowering of the section and for moving the section. The jacks may be used for attaching one section to an adjacent section which is on the ground, or else a set of jacks may be provided on each of the two adjacent sections being coupled together.

A distance (parallel to the tunnel axis) between the cable sagging arm and the cable positioning arm is preferably at least 1.5 times the distance between final installation positions. This means one arm can be positioning the cable and the other can be applying the sagging, so that these operations are carried out as the apparatus moves along the tunnel (without having to change direction).

The cable positioning arm can comprise a roller arrangement for surrounding the cable on the end of an arm, the arm being of adjustable length and rotatable about an elongate axis of the vehicle. This arrangement enables the arm to move between any pair of locations in substantially the full tunnel cross section. The cable sagging arm can comprise a guide arrangement for applying a downward sagging force to the cable. The cable positioning arm and the cable sagging arm are preferably interchangeable so that the apparatus can be driven in either direction.

The invention also provides a method of securing a cable or pipe within a tunnel, comprising: moving a first portion of the cable/pipe from a temporary installation position to a final installation position using a cable/pipe positioning arm of an installation apparatus, securing the first portion of the cable/pipe to a securing point on a wall of the tunnel; moving a second portion of the cable/pipe from a temporary installation position to a final installation position using the cable/pipe positioning arm; applying a desired amount of sagging to the length of cable/pipe between the first and second portions using a cable/pipe sagging arm of the installation apparatus; and securing the second portion of the cable/pipe to a securing point on a wall of the tunnel.

This method enables sequential cable fixing and sagging, with an installation apparatus moving along the tunnel (without needing to change direction). The step of applying sagging and securing the cable can thus be carried out in a sequence along the length of the cable, such that the cable is secured at discrete locations along its length, with the same amount of sagging applied between adjacent locations.

The invention also provides a method of installing a cable or pipe in a tunnel, comprising: towing the cable/pipe into the tunnel, and mounting the cable/pipe in a temporary installation position; securing the cable/pipe using the method of the invention.

Mounting the cable in a temporary installation position can comprise suspending the cable from a beam at the top of the tunnel using ties spaced along the cable.

Brief description of the drawincis

An example of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a typical tunnel cross section for a 3m diameter tunnel; Figure 2 shows how the cables are to be mounted on support structures; Figure 3 shows how a cable is provided to the tunnel via an access shaft; Figure 4 shows the equipment used to tow the cable into the tunnel in more detail; Figure 5 shows a tug, cables, support structure, I-beam and hanger inside the tunnel; Figure 6 shows a cable in a temporary position at the start of the securing method of the invention; Figure 7 shows the towing more clearly to position the cable as in Figure 6; Figure 8 shows a transfer process forming part of the method of the invention; Figure 9 shows a cable sagging process forming part of the method of the invention; Figure 10 shows a power module part of the apparatus of the invention; Figure 11 shows one of the two wheeled axle unit sections of the apparatus of the invention; Figure 12 shows the hydraulic assembly of the sections of the apparatus; Figures 13 and 14 show one preferred version of the apparatus of the invention more clearly, in side view in Figure 13 and in end view in the tunnel in Figure 14.

Detailed description

The invention relates to the installation of cables or pipes in tunnels, and in particular relates to a motorised vehicle used for the installation, as well as to the method of installation which uses the vehicle. The description below is for the preferred use of the apparatus for installing electrical cables.

Figure 1 shows a typical tunnel cross section for a 3m diameter tunnel 10. A side of the tunnel has a cable support structure 12 with mounting positions for three cables 14, as shown.

Figure 2 shows how the cables are to be mounted on the support structures 12.

The support structures are bolted to the tunnel wall, 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 so that short circuit straps 16 can be fitted mid-way between the support locations.

The cable can for example comprise a high power electric 400kV cable. Common tunnel diameters are 3m and 4m, and the cables can be provided in lengths of the order of 1km, with typical diameters up to 160mm, although the invention is not limited to any particular cable sizes. A ilOOm length typically weighs approximately 55 tonnes (50 KgIm).

The invention provides a two stage mounting operation. In a first stage shown in Figure 3, the cable is lowered into the tunnel and is tugged into position. As the cable is advanced along the tunnel, it is suspended in a temporary position suspended from the tunnel roof. In particular, a support I-beam 19 typically runs along the tunnel roof.

A cable guiding structure 20 facilitates entry of the cable into an access shaft 22.

The access shaft can comprise a 1.5m x 2m opening, which may be approximately Sm long. The tunnel also has a working envelope of approximately 2m x 1.5m so that there is space for the passage of staff around the working envelope. As the cable is advanced along the tunnel, rollers 24 are fitted over the I-beam 19 with cable hangers 26 that support the cable 14.

The equipment used to tow the cable into the tunnel into this temporary position is shown in more detail in Figure 4.

The cable is offloaded from a drum 30 in an offload area 31. In addition to being pulled by the tug 32, the cable is driven by caterpillars 34 and electric rollers 35 in region 37. Various load sensors 36 are used for feedback purposes. Feedback from the sensors as well as CCTV cameras is provided to a control module 38.

Thus, the cable is lowered using controlled motorised rollers which control the rate of cable advance. The tunnel typically has a minimum tunnel bend radius of 250m.

FigureS shows the tug 32, cables 14, support structure 12, I-beam 19 and hanger 26 inside the tunnel.

The invention provides a design of tug which can perform the towing task explained above, and this aided by a traction control system. In addition, the design can also perform cable movement from the temporary suspended position to the desired supported position 42, namely the transfer represented by arrow 44. In addition, the apparatus can provide a desired amount of sag between adjacent support structures 12.

Figure 6 shows the cable in its temporary position. The rollers 24 are spaced by Kevlar bars 60 so that the regular spacing of the rollers 24 is maintained when they are pulled along the I-beam from the entry point of the cable. There may for example be hundreds of the rollers 24 along the length of the cable. When towing the cable, the bars 60 function as the primary tension members rather than the cable. This towing is shown in Figure 3 and also in Figure 7, and the cable is also pushed from the access shaft end by one of the caterpillars. The towing is typically carried out at walking pace, for example 3km/hr.

When the cable is in its temporary position along its full length, the device of the invention performs the transfer and sagging process. The transfer process is shown schematically in Figure 8.

The apparatus used is a motorised vehicle. A cable positioning arm 80 is at one end of the vehicle which is controllable to move a cable from the temporary position to a final installation position, as shown by arrow 82. A cable sagging arm 84 is at the other end of the vehicle which is controllable to apply a desired amount of sagging to a length of cable between adjacent support structures 12.

This process is shown more clearly in Figure 9. The cable positioning arm 80 comprises a roller arrangement for surrounding the cable on the end of an arm.

The arm has adjustable length and is rotatable about an elongate axis of the vehicle, so that the movement of arrow 44 in Figure 5 can be provided to the cable.

After a first portion of the cable has been moved from the temporary installation position to the final installation position it is secured in place, for example as shown at location 86. A second portion of the cable is also moved from the temporary installation position to a final installation position using the cable positioning arm, as shown at location 88. At the position shown in Figure 9, the cable sagging arm 84 is in position to apply a desired amount of sagging to the length of cable between the first and second locations 86,88. The cable at the second location 88 is then secured to the securing point on the wall of the tunnel to retain and fix the sagging amount that has been set.

The rollers of the cable position arm surround the cable, and the free end of the cable is fed through the opening defined by the rollers. The cable positioning arm thus provides support for the cable for the entire operation. As the vehicle 32 advances along the tunnel (in direction 90), the cable hangers are removed, to allow the cable to be moved to the support structures 12. The cable is elevated to enable release of the cable hanger, before the cable is moved to the support structure. The cable sagging arm comprises a guide arrangement for applying a downward sagging force to the cable or for lifting the cable if required.

The distance along the tunnel axis between the cable sagging arm and the cable positioning arm is preferably at least equal to the distance between final installation positions. The distance is preferably approximately equal to the distance between supports 12. This means that the cable sagging arm has reached the position where cable sagging is controlled when the cable positioning arm is in a suitable position for positioning the cable at the next support 12 (as shown in Figure 9).

The cable installation and sagging functions are alternated. The machine travels a distance corresponding to the pitch between installation points (e.g. 7.2m) then remains stationary for one cable installation and one cable sagging operation.

The amount of sag can be controlled by measurement, for example marking the desired sag on the side wall of the tunnel, for example with 195 -205mm of sag from the horizontal. The cable positioning arm and the cable sagging arm are interchangeable so that the device can be driven in both directions.

In the example shown in Figure 9, the vehicle has five sections; a central motor section, two axle unit sections and two end cab sections. This modular design enables the sections to be lowered into the access shaft 22 (Figure 3) individually, and they can be assembled at the base of the access shaft. A heavy duty crane system is used to lower the modules down the access shaft. More generally, the vehicle can comprise at least three sections which are adapted to be assembled within the tunnel.

A first, central section 100 is shown in Figure 10, and comprises a power module.

One of the two wheeled axle unit sections 102 is shown schematically in Figure 11, simply to show that the modular units can be designed to be easily installed in a confined space.

There are many different ways to design the different sections to enable them to be coupled together within the confines of the tunnel.

In one example, the central section comprises a hydraulic arrangement 104 for coupling the sections together. This can be by drawing the axle unit section in, thereby pivoting closed, as shown in Figure 12. All sections can be assembled in this way, so that the user only needs to implement a very coarse alignment, and a hydraulic system controls the accurate assembly of the modules.

In the case of a five module arrangement, the front and rear cab sections may be manually secured, as the alignment is less critical.

Another arrangement uses roller jacks to support the sections and enable them to be brought together. Each roller jack comprises a roller at the bottom of a hydraulic shaft. The shaft is secured to the sides of the vehicle section, for example one in each corner. The securing can be simply with engagement of headed pins (e.g. two such pins) of the jack and keyhole slots of the vehicle component. Jacking the roller down lifts the vehicle section, and at the same time lifts the head of the pin to the position where it cannot laterally come out of the narrow part of the keyhole slot. The jacks can be controlled by a power pack, both for controlling the raising and lowering operations, but also to drive the rollers so that the vehicle sections are driven together in a powered manner. Independent control of the jacks can enable tilting front to back or side to side as required.

This arrangement enables the operation to be carried out remotely, and the jacks together essentially define a powered trolley for lifting, lowering and driving, which is temporarily attached to the vehicle section.

The connection between vehicle sections can be achieved with hook and pin connections. A hook on one vehicle section can for example be lifted over a pin on the adjacent vehicle section using the raising and lowering function of the jacks.

These hook/pin connections then provide coupling in the elongate direction, and retaining pins can be used to prevent relative vertical movement so as to keep the hook and pin connections engaged.

The remotely controlled jacking arrangement can be used to connect the various vehicle sections in a sequence. Finally, the vehicle is resting on its own wheels, and the jacks can be removed.

Figures 13 and 14 show one preferred version of the vehicle more clearly, in side view and in end view in the tunnel. These figures show that the wheeled axle units each comprise two wheels (for example of 700mm diameter and 300mm width) having rotation axes 140 which can be adjusted, such that the wheels can be positioned for rolling on a flat surface or for rolling on opposite inclines. The axle units can thus be set for different tunnel diameters. A two or four wheel steering system can be provided. A tow point 142 is used for the initial towing operation Figure 14 shows most clearly how the positioning arm enables the cable to be moved between any two positions in the tunnel cross section, by combining linear and rotational control. The same two degrees of freedom can be provided in the sagging arm 84, and a downward force can be applied by rotating the arm once the cable has been engaged.

The cable securing method can be carried out by driving the vehicle along the tunnel, with manual removal of the hangers. The vehicle can be designed so that the cable positioning of one section of cable and the cable sagging of another section are at the same vehicle position. This provides an efficient process, with the vehicle advanced in steps, and at each step a dual positioning and sagging operation is carried out. By controlling the sagging to be the same for multiple cables (installed one after the other) cable ties can more easily be fitted.

There are a number of safety measures which should be taken in the operation of the apparatus and some of these measures are outlined below. Many of these are implemented by software which forms part of the control system for the apparatus.

The machine is bi-directional in operation and requires an operator in each cab in order to allow the machine to move, except in an Emergency recovery mode where a key operated override switch will allow a single operator to control all functions of the machine without interruption by any safety override system.

In normal operation, the two operator control stations conform to a master I slave protocol where only one of the operators has control of the traction power and he will only be able to drive the machine in the direction in which he faces.

In order to make the machine travel in the opposite direction he must hand over master control to the operator in the other cab.

Similarly, the master operator will have control of the steering of the wheels at his end of the machine. Part of the procedure for handing over control to the other operator is to set these wheels to the straight ahead position and to engage a steering lock.

The slave operator must be operating his dead-man control (either a button or a foot pedal) in order for the machine to move. Should the slave operator release his dead man control the software will bring the machine to a controlled stop.

Both operators will also have access to an emergency stop button which will cause an immediate full emergency brake application.

The machine is designed to be used in circular bore tunnels down to 1.5m radius.

In such small radius tunnels there could be a risk of overturning the vehicle by driving up the wall' of the tunnel. In order to minimise this risk the machine is fitted with an inclinometer which causes the software to give the master operator a warning if the machine begins to roll and which, if he fails to take corrective action, will bring the machine to a standstill. In this latter case it will require a supervisor to use a key to engage emergency recovery mode in order to move the machine.

The train of trolleys 24 to which the cable is attached will be provided with brakes at each end of the train. These brakes must be under the control of the software.

Transducers on the vehicle transmit signals to the control station indicating whether or not the vehicle engine is running, the status of the emergency stop circuit on the vehicle, the load on the tow points and possibly also the vehicle speed and distance travelled.

Pressure switches are fitted to monitor the charge pump pressure and the loop circuit pressure of the hydraulic equipment. These will provide control inputs to the software to ensure that the pump is not run dry of hydraulic fluid and to stop the machine in the event of a catastrophic hydraulic leak. Unless the machine is installing and sagging the cable, the hydraulic arms must be in the parked position.

Proximity detectors are used to allow the software to detect that this condition is met when relevant.

Whenever the machine moves from a standstill the software must first give a one second blast on the warning horn.

In addition to the general safety considerations above, there are provisions specific to the different operating modes.

In the cable loading mode, the vehicle is required to provide a steady pull on the cable and to draw the train of trolleys into the tunnel as the cable is loaded into the suspension straps. The control will be a dial control for varying the pull force, a joystick control giving forward or reverse selection, and a dead-man safety control.

In this mode, the maximum travel speed will be set within the software to prevent out of control acceleration and movement of the vehicle in the event of failure of the tow line and when the end of the cable is released from the drum.

The operators of the vehicle are controlled by verbal instructions given via 2-way radio communications with a control station. The control station operator has an emergency stop button which is capable of stopping every machine in the cable loading array including the cable tractor. In the case of the cable tractor this emergency stop function need only cut off the traction drive and apply the parking brake but can leave the engine running.

The pull force on the cable and the pull force on the tow connection to the train of trolleys is monitored by load cells and these loads are transmitted by radio signal to the control station.

In the cable loading mode the pull force on the cable are limited and the software monitors the output from the cable tie load cell and prevents this being overloaded.

In the cable delivery mode, the operator will have complete control over the vehicle speed and the same dial control is set to maximum travel speed with the joystick control then acting as a variable speed control.

The vehicle is coupled to the train of trolleys and loosely tethered to the cable itself. Both of these connections have load cells which are monitored by the software to ensure that neither connection is being pulled too hard. In the event of a derailment or failure of one or more of the trolleys the software should immediately bring the machine and load to a controlled stop.

The software provides gentle ramping up and ramping down of speed to prevent overloading of the tow lines and to reduce the risk of the cable over running the vehicle during deceleration. The operators' control inputs may be overridden by the inclinometer.

In the cable installation and sagging mode, the vehicle has a very low maximum speed and will usually travel in the opposite direction to that used for cable delivery. As the vehicle moves it passes underneath the train of trolleys from which the cable is now slowly released -by a man walking ahead of the vehicle -to allow the hydraulic arm on the end of the vehicle to be used to thread the cable onto the wall brackets.

During cable sagging, the cable may need to be lifted or forced down at the mid span position in order to achieve the correct amount of sag, and either of these can be achieved.

During the sagging operation the machine is parked with parking brake applied to provide a stable platform for the operation of the hydraulic arms. During the cable installation (i.e. threading) the machine must travel at a slow speed and the speed again ramps up and down in a controlled manner.

Once the correct amount of sag is introduced into the cable an operator must pass onto a walkway mounted on the side of the vehicle to fit and secure a cable clamp to the wall bracket which will be roughly adjacent to the middle of the vehicle. This could be done by a third party. The system will be aware how many operators are working on the vehicle, so that the software can check that the appropriate numbers of dead-man controls are being operated before allowing the vehicle to be moved.

Once the whole length of the cable has been fixed on the wall brackets the machine will be re-coupled to the train of trolleys in order to return them ready to re-load with the next cable. In this mode the operator will have complete control over the vehicle speed and it is envisaged that the dial control will set maximum travel speed whilst the joystick control acts as a variable speed control.

In each of the cable delivery, loading modes and installation modes, one operator will steer the vehicle and operate the joystick and dial controls in his cab, and the other operator observes the cable and has the dead man control. A solo running mode is defined for driving the vehicle with no towing. A maximum speed of around 7km/h is appropriate, and the load cells for monitoring towing forces do not need to be monitored.

The invention provides a modular design of vehicle which offers versatility, and allows implementation of a semi-automated cable sagging process, and which reduces health and safety risks associated with alternative methods of introducing sagging into the cables. The process is more efficient and can thus reduce operation times.

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.

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

Claims

Claims 1. An apparatus for installing cables or pipes in tunnels, comprising a motorised vehicle having a cable/pipe positioning arm at one end of the vehicle which is controllable to move a cable/pipe from a temporary installation position to a final installation position, and a cable/pipe sagging arm at the other end of the vehicle which is controllable to apply a desired amount of sagging to a length of cable/pipe between adjacent final installation positions.
2. An apparatus as claimed in claim 1, wherein the motorised vehicle comprises at least three sections which are adapted to be assembled within the tunnel.
3. An apparatus as claimed in claim 2, wherein a first, central section comprises a power module, a second section comprises a first wheeled axle unit and a third section comprises a second wheeled axle unit.
4. An apparatus as claimed in claim 3, wherein each wheeled axle unit comprises two wheels having rotation axes which can be adjusted, such that the wheels can be positioned for rolling on a flat surface or for rolling on opposite inclines.
5. An apparatus as claimed in claim 2 or 3, wherein the central section comprises a hydraulic arrangement for coupling the sections together.
6. An apparatus as claimed in any one of claims 2 to 4, further comprising a set of jacks for attachment to a section for controlling the raising and lowering of the section and for moving the section.
7. An apparatus as claimed in any preceding claim, wherein a distance along the tunnel axis between the cable/pipe sagging arm and the cable/pipe positioning arm is at least equal to the distance between final installation positions.
8. An apparatus as claimed in any preceding claim, wherein the cable/pipe positioning arm comprises a roller arrangement for surrounding the cable/pipe on the end of an arm, the arm being of adjustable length and rotatable about an elongate axis of the vehicle.
9. An apparatus as claimed in any preceding claim, wherein the cable/pipe sagging arm comprises a guide arrangement for applying a downward sagging force or an upward lifting force to the cable/pipe.
10. An apparatus as claimed in any preceding claim, wherein the cable/pipe positioning arm and the cable/pipe sagging arm are interchangeable.
11. A method of securing a cable or pipe within a tunnel, comprising: moving a first portion of the cable/pipe from a temporary installation position to a final installation position using a cable/pipe positioning arm of an installation apparatus, securing the first portion of the cable/pipe to a securing point on a wall of the tunnel; moving a second portion of the cable/pipe from a temporary installation position to a final installation position using the cable/pipe positioning arm; applying a desired amount of sagging to the length of cable/pipe between the first and second portions using a cable/pipe sagging arm of the installation apparatus; and securing the second portion of the cable/pipe to a securing point on a wall of the tunnel.
12. A method as claimed in claim 11, wherein the step of applying sagging and securing the cable/pipe is carried out in a sequence along the length of the cable/pipe, such that the cable/pipe is secured at discrete locations along its length, with the same amount of sagging applied between adjacent locations.
13. A method of installing a cable or pipe in a tunnel, comprising: towing the cable/pipe into the tunnel, and mounting the cable/pipe in a temporary installation position; securing using the method as claimed in claim 11.
14. A method as claimed in claim 13, wherein mounting the cable/pipe in a temporary installation position comprises suspending the cable/pipe from a beam at the top of the tunnel using ties spaced along the cable.