Method and apparatus for installing individual power cable spans in a tunnel

Abstract

The present disclosure relates to a method for installing a single power cable span in a tunnel, the tunnel having an entrance and an exit, the method comprising: positioning a cable head near the entrance; laying the single power cable span in the tunnel past the exit, the laying of the single power cable span in the tunnel comprising repeating the following sub-steps until the cable head reaches a terminal point outside the tunnel: at the entrance, connecting a trolley on a track in a sliding manner, the track extending longitudinally along the tunnel between the entrance and the exit; coupling the trolley to a pulling rope and to the single power cable span, moving the trolley along the track by pulling the pulling rope; coupling another trolley after a predetermined length; at the exit, decoupling the trolley from the pulling rope and from the single power cable span and removing it from the track; locking at least the trolley closest to the exit on the track inside the tunnel when the cable head reaches the terminal point. According to another aspect, the present disclosure relates to an apparatus for installing a single power cable span in a tunnel.

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for installing power cables in a tunnel. Background Technology

[0002] Underground cables are more expensive than equivalent overhead lines because they must be larger to reduce resistance and heat generation. They require special insulation and / or cable cooling, typically provided by forced ventilation or water cooling. Furthermore, the transition between overhead and underground cables requires termination points. This contributes to the higher cost.

[0003] However, underground cables help ensure uninterrupted power supply, which is uncommon in overhead systems due to factors such as strong winds and storms, and structural failures. Underground cables can transmit electricity in densely populated areas where land is expensive and environmental or aesthetic sensibilities are important. Therefore, in some areas, the advantages of underground cables outweigh their disadvantages.

[0004] In urban areas where direct burial would cause unacceptable disruption, tunnel installations, typically 25-30 meters deep, are commonly used for underground cable installation. The advantages of this approach are that other underground services, such as water supply and sewage treatment, remain unaffected, and there is greater freedom in choosing cable routes; for example, cable routes can cross rivers or railways.

[0005] Positioning single-span power cables (especially high-voltage cables) into tunnels presents challenges. Cables are supplied by reels that are typically unsuitable for tunnel installation, requiring the cable to be threaded longitudinally into the tunnel. Generally, a single power cable span is shorter than the tunnel in which it is deployed, necessitating multiple joints due to increased cost, installation time, and safety concerns. Furthermore, joints are weak points where cable installations can fail. Additionally, as explained above, due to the weight of underground high-voltage cables (e.g., a 400 kV cable weighs approximately 40 kg / m), deploying a single cable exceeding 2 km in length presents problems in terms of supply reel management and the tension applied to the cable.

[0006] GB 2383 200A pertains to cable installation within tunnels. Cables are supplied on reels and guided to the tunnel ceiling using motorized rollers. Inside the tunnel, the cable is supported on support beams by beam rollers that support cable hangers. The beam rollers can roll along the support beams, carrying the cable with them. Beam rollers are provided at the tunnel opening as the cable moves forward. The cable is completely unwound and supported by the support beams along its entire length. Once a 1km length has been positioned at the desired location, it is moved to clamps on the sidewall. After the cable has been moved to the clamps, these lengths of cable are joined together.

[0007] GB 2468 883A relates to cable installation in tunnels. Known cable installation methods include so-called hand-pulling, nose-pulling, and adhesive-pulling. Adhesive-pulling is best suited for heavy-duty cables operating for extended periods. The cable is moved forward along the tunnel from a temporary position suspended above the tunnel ceiling. As the cable moves forward along the tunnel, rollers are mounted on I-beams with cable hangers supporting the cable. The rollers are spaced apart by Kevlar rods, thus maintaining a regular spacing between them as the rollers are pulled along the I-beams from the cable's entry point. Summary of the Invention

[0008] The applicant aims to provide a method and apparatus for installing power cables in tunnels, in which long cable spans, particularly cable spans longer than 2 km, can be deployed without the need for joints.

[0009] This objective is achieved through a method for installing a single power cable span in a tunnel, in which the cable is continuously clamped by multiple trolleys that slide along tracks installed in the tunnel during installation and, once installed, act as fixed supports for the cable. During installation, the trolleys are pulled by ropes attached to them, moving the single cable span along the tunnel from one end to the other. No tension is applied directly to the cable head, and no pulling aids along the middle of the tunnel are required. The cable is installed in its final position, attached to a trolley fixed inside the tunnel, eliminating the need to move the cable within the tunnel. Therefore, the entire process is rapid and requires simple equipment. Similarly, cable replacement, for example, in the event of a fault, is also quick and simple.

[0010] Therefore, this disclosure relates to a method for installing a single power cable span in a tunnel having an entrance and an exit, the method comprising the following steps:

[0011] - Position the head of the cable span near the tunnel entrance;

[0012] - Lay a single power cable span inside the tunnel, passing through the tunnel exit.

[0013] The step of laying a single power cable span in the tunnel includes repeating the following sub-steps until the cable head reaches the end point outside the tunnel:

[0014] - At the tunnel entrance, a trolley is slidably connected to a track that extends longitudinally along the tunnel between the tunnel entrance and the tunnel exit;

[0015] - Connect the trolley to the pull rope and a single power cable span;

[0016] -The trolley is moved along the track by pulling the rope;

[0017] - Connect another vehicle after the predetermined length;

[0018] - At the tunnel exit, separate the trolley from the ropes and cables, and remove the trolley from the track;

[0019] - When the cable head reaches the end, lock at least the trolley closest to the tunnel exit onto the track inside the tunnel.

[0020] According to one embodiment, at least a plurality of trolleys are locked onto tracks within the tunnel. All trolleys within the tunnel can be locked stationary onto the tracks.

[0021] According to one embodiment, the method further includes the step of dragging the cable head to the endpoint by an auxiliary pull rope when the cable head reaches a predetermined position outside the tunnel and is disconnected from the trolley.

[0022] According to one embodiment, when the cable head reaches a predetermined endpoint outside the tunnel, a predetermined sag is assigned to a single power cable span inside the tunnel in the following manner:

[0023] - Lock the trolley closest to the tunnel exit onto the track;

[0024] - Disconnect the trolley closest to the tunnel exit from the pull rope; and

[0025] - Pull the upward-moving trolley with a rope until the cable sections between all the trolleys in the tunnel are given the predetermined sag.

[0026] According to an alternative embodiment, a predetermined sag is assigned to the cable span as it moves forward along the tunnel. This process includes providing a sag device near the tunnel entrance and operating the device to push downwards a portion of the cable substantially equidistant from two trolleys, thereby providing the predetermined sag.

[0027] According to another aspect, this disclosure relates to an apparatus for installing a single power cable span in a tunnel, comprising:

[0028] - At least one track, which is fixedly installed in the tunnel along the longitudinal direction;

[0029] - The pulling device and the rope driven by the pulling device; and

[0030] - A plurality of trolleys slidably connected to a track, each of the trolleys including means for releasably connecting the trolley to a pull rope and means for releasably connecting the trolley to electricity.

[0031] In one embodiment, the device includes an auxiliary pulling device and an outlet auxiliary pulling rope driven by the auxiliary pulling device, which can be connected to the head of a single power cable span.

[0032] In this specification and claims, a high-voltage (HV) cable refers to a cable with a rated voltage higher than 30 kilovolts.

[0033] Using the methods and apparatus of this disclosure, long single spans of power cables can be installed without the need for joints to connect subsequent cable spans. Therefore, installation is easier, cheaper, and the installed cables are more reliable. Attached Figure Description

[0034] Referring to the accompanying drawings, further features and advantages will become more apparent from the following description of some embodiments given by way of example, wherein:

[0035] Figures 1a-1c Exemplary steps for transporting high-voltage cables near a tunnel entrance according to an embodiment of the method of this disclosure are shown;

[0036] Figures 2a-2c An apparatus for installing a single-span high-voltage cable in a tunnel, according to an embodiment of the present disclosure, is shown.

[0037] Figures 3a-3h Exemplary steps of a method for installing a single-span high-voltage cable in a tunnel according to embodiments of the present disclosure are shown;

[0038] Figure 4 An exemplary configuration of several single-span high-voltage cables installed in a tunnel using methods and apparatus according to embodiments of this disclosure is shown;

[0039] Figure 5 A descent device is shown for installing a single-span high-voltage cable in a tunnel according to an embodiment of this disclosure. Detailed Implementation

[0040] For the purposes of this specification and the appended claims, unless otherwise stated, all figures indicating quantities, amounts, percentages, etc., shall be understood to be modified in all cases by the term "about". Furthermore, all ranges include any combination of the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically listed herein.

[0041] In at least one aspect of the foregoing, this disclosure may be implemented based on one or more of the following embodiments, which may be combined together.

[0042] For the purposes of this specification and the appended claims, the words “a” or “an” should be understood to include one or at least one, and the singular includes the plural, unless it is obvious that it has a different meaning. This is done merely for convenience and to give the general meaning of this disclosure.

[0043] Referring to the accompanying drawings, the purpose of the method and apparatus according to this disclosure is to transfer a single-span high-voltage cable 100 from a starting point 101 ( Figure 1a Locate the endpoint 102 ( Figure 3f The cable path is partially within tunnel 103, with the remainder outside the tunnel. In the illustrated configuration, tunnel 103 is below ground level, and the starting point 101 and the ending point 102 are above ground level. The cable path includes an entrance shaft 104 communicating with tunnel entrance 106 and tunnel exit 107, respectively. Figure 1c ) and exit shaft 105 ( Figure 2c ).

[0044] The method of installing a single cable span 100 in the tunnel 103 includes placing the head 108 of the cable 100 ( Figure 1c The step of locating near tunnel entrance 106. This step may include one or more of the sub-steps described below.

[0045] like Figure 1a As shown, depending on the location of the starting point 101, a single cable span 100 can be delivered at the starting point 101. The single cable span 100 is wound in a basket or turntable 109, for example, transported by a vehicle 110 such as a wheeled vehicle or even a ship. Using, for example, a pickup arm (not shown), the single cable span 100 can initially be unloaded from the basket 109. The pickup arm picks up the cable head 108 and moves it into the transition structure 111, guiding and holding the cable 100 from the basket 109 to the entrance shaft 104. As the cable 100 moves along the transition structure 111, the cable 100 is gradually unloaded from the basket 109.

[0046] exist Figure 1b In the illustrated embodiment, the transition structure 111 may include one or more trenches 112, which may optionally accommodate rollers, spurs, pushers 121 for moving, guiding, and / or slowing the forward movement of cables toward the inlet shaft 104. The transition structure 111 may also include a connector chamber 113 for connecting cable segments to the network after deployment.

[0047] In one embodiment, such as Figure 1c As shown, for example, a plurality of first supports 114 made of steel are installed in the entrance shaft 104. The first supports 114 may have rollers for guiding cables.

[0048] The step of positioning the head of cable 103 near the tunnel entrance 106 may further include a sub-step of installing an auxiliary pulling device (e.g., an auxiliary entrance winch 115) at the bottom of the entrance shaft 104 to pull the cable head 108 near the tunnel entrance 106 via an auxiliary entrance rope 122. The aforementioned pusher 121 and auxiliary entrance winch 115 may be driven synchronously.

[0049] The method also includes the step of laying a single cable span 100 in tunnel 103. For this purpose, installation equipment is set in tunnel 103 and near tunnel entrance 106 and exit 107, for example in entrance shaft 104 and exit shaft 105, which will be described in detail below.

[0050] like Figure 2a As shown, at least one track 1 is installed in tunnel 103, extending longitudinally from tunnel entrance 106 to tunnel exit 107. In one embodiment, for each individual cable span 100 to be deployed in tunnel 103, one track 1 is fixed to the tunnel wall. In the case of installing multiple cables, multiple corresponding tracks 1 (e.g., those parallel to each other) can be installed before or after deploying the cable spans on the tracks. Figure 2a (As shown). For example, in the case where tunnel 103 has a circular or semi-circular cross-section, track 1 is installed circumferentially on the tunnel wall along the cylindrical tunnel wall, parallel to its longitudinal axis.

[0051] In one embodiment, for installing the track 1 in the tunnel 103, a plurality of track support structures 2 for supporting the track 103 are fixed to the tunnel wall along the tunnel. The track support structures 2 are, for example, made of steel and may be spaced at equal intervals along the length of the tunnel, for example, not exceeding 9 meters. In one embodiment, the track support structures 2 are arc-shaped to fit a circular or semi-circular tunnel wall, for example... Figure 2a As shown. The track 1 and track support structure 2 are fixedly installed in the tunnel 103 because they are used both for laying individual cable spans 100 and for supporting them in the tunnel 103 after installation, which will be described in more detail below.

[0052] In one embodiment, a traction device 3, including a traction winch, is installed near the tunnel exit 107, for example, at the exit shaft 105. Figure 2c As shown. Figure 2b As shown, a rope buffer, including, for example, a spool 4, is positioned near the tunnel entrance 106, such as at the entrance shaft 104. A pull rope 5 is stored in the rope buffer, for example, wound around the spool 4, and connected to a traction winch 3 extending longitudinally along the tunnel 103, enabling the traction winch 3 to pull the rope 5 stored in the spool 4. In one embodiment, the pull rope 5 is positioned parallel to and extends close to the track 1.

[0053] like Figure 3aAs shown, a first carriage 8 is connected to a track 1 on which it can slide, for example at a tunnel entrance 106. To minimize friction with the track 1, the carriage 8 may include bearings 9 with a low coefficient of friction. In one embodiment, the track 1 is I-shaped, and the bearings 9 engage the I-shaped track 1 on both sides. The carriage 8 is then connected to a rope 5 and individual cable spans 100, particularly to cable heads 108, for example in the order described above. For this purpose, the carriage 8 includes a device 10, such as a first clamp, for releasably connecting the rope 5 to the carriage 8, and a device 11, such as a second clamp, for releasably connecting the individual cable spans 100 to the carriage 8. The first device 10 and the second device 11 are designed such that, once connected to the cable 1 and the rope 5, the carriage 8 can slide along the track 1 due to the tension applied by the rope 5, and the cable 1 can be transported integrally without tensile stress being applied to it. In one embodiment, the first clamp of device 10 includes two first halves 12 for releasably clamping rope 5, and the second clamp of device 11 includes two second halves 13 for releasably clamping cable 1.

[0054] Then, as Figure 3b and Figure 3c As shown, the trolley 8 moves along the track 1 by pulling the rope 5 driven by the pulling device 3, and slides along the track 1 for a predetermined first longitudinal distance L, which is less than the total length of the track 1. During this operation, a single cable span 100 is transported longitudinally along the track 1 for substantially the same first longitudinal distance L. For example, the predetermined first longitudinal distance L is no more than 9 meters. The minimum distance can be 1 meter or less, but those skilled in the art will understand that the shorter the distance L, the higher the number of trolleys required for cable deployment, which means increased installation costs and time.

[0055] Then, other trolleys 8, having the same characteristics as the first trolley 8, are connected one after another to track 1 at the tunnel entrance 106, as follows: Figure 3c As shown. Then, as described for the first carriage, each additional carriage 8 is connected to rope 5 and a single cable span 100. Each additional carriage 8 is located at a distance from the preceding carriage 8 (in... Figure 3c In this case, the first carriage 8 is connected to the cable section at a certain longitudinal distance. Then, as already described for the first carriage 8, each additional carriage 8 is slid along the track 1 a predetermined additional longitudinal distance, for example, equal to the first longitudinal length L. During this operation, the individual cable span 100 is further moved longitudinally along the track 1 by the same distance.

[0056] Once the first vehicle 8 reaches the track end near the tunnel exit 107, the cable head 108 is detached from the first vehicle 8.

[0057] The individual cable span 100 is further moved so that the cable head 108 is transported to the outside of the outlet shaft 105, specifically to the overhead terminus 102, as... Figure 3f As shown. During this movement, cable span 100 separates from an appropriate number of trolleys 8, and at the tunnel entrance 106, cable span 100 engages with an equally appropriate number of other trolleys 8.

[0058] In one embodiment, an auxiliary traction device, such as an auxiliary outlet winch 116, is located at the overhead end point 102. Figure 3f An auxiliary pulling device drives an outlet auxiliary pull rope (not shown) connected to the cable head 108 to pull a single cable span 100 toward the end point 102. The tension applied to the cable head 108 by the outlet auxiliary pull rope (and therefore to the single cable span 100) is partially mitigated by the traction force of the pull rope 5, which remains operatively connected to most of the length of the single cable span.

[0059] An exit transition structure 117 is provided, which guides and holds a single cable span 100 and an exit auxiliary guy rope from the tunnel exit 107 via an exit shaft 105. A second trench 118 can accommodate a portion of the exit transition structure 117. The second trench 118 can connect the endpoint 102 to the exit shaft 105.

[0060] In one embodiment, a plurality of second supports 120, for example made of steel, are installed in the outlet shaft 105. Similar to the first support 114, the second supports 120 may have rollers for guiding the cable head 108 and assisting the pull rope.

[0061] At endpoint 102, the cable head 108 of a single cable span 100 can be connected to one or more power cables of the power grid through a second joint chamber (not shown).

[0062] As mentioned above, in order to lift the head 108 of a single cable span 100 outside the tunnel 107, the guy rope 5 and a predetermined number of trolleys 8 are disconnected from the single cable span 100, and the disconnected trolleys 8 are removed from the track 1. Figure 3d Then, as Figure 3e As shown, the pull rope 5 (which continues to pull another trolley 8, and thus the single cable span 100 connected to it) and the auxiliary exit pull rope (connected to the cable head 118) driven by the auxiliary exit winch 116, for example, in a synchronous manner, until the cable head 108 reaches a predetermined position outside the tunnel, for example, until it reaches the end point 102. Depending on the length of the single cable span 100 to be withdrawn from the tunnel 103, the other trolley 8, in addition to the first trolley 8, can be sequentially disconnected from the pull rope 5 and the single cable span 100 and removed from the track 1.

[0063] In one embodiment, once the cable head 108 reaches the end point 102, at least some or all of the trolleys 8 within the tunnel 103 can be statically locked to the track 1, thereby providing permanent support for the deployed cable span 100. The choice of the number of trolleys 8 remaining in the tunnel 103 can be determined by installation considerations, such as cable weight.

[0064] According to one embodiment, when the cable head reaches a predetermined endpoint outside the tunnel, the pull rope remains connected to the trolley inside the tunnel.

[0065] In one embodiment, the method further includes the step of giving a single cable span 100 a sag, such as Figure 3g-Figure 3h and Figure 4 As shown. The steps include the following sub-steps: when the cable head 108 has reached the predetermined endpoint 102 outside the tunnel 103, the trolley 8 closest to the tunnel exit 107 is locked to the track 1. Figure 3g As shown, the locked trolley 8 is disconnected from the rope 5, while maintaining connection to the individual cable span 100. Then, the rope 5 is pulled by the pulling device 3 (as shown). Figure 2c As shown), this pulls all the trolleys 8 that are still sliding on track 1 (unlocked) and still connected to cable 1 and guy rope 5. This pulling may require adding at least one additional trolley 8 at tunnel entrance 106 and connecting it to a single cable span 100 and guy rope 5. Figure 3h As shown, the pulling continues until the cable sections between all the trolleys 8 inside tunnel 103 reach the predetermined sag.

[0066] In one embodiment, the step of giving the cable a predetermined sag further includes an additional sub-step of applying a vertical load to the cable portion, for example, at the middle of the cable portion. Figure 3h (The central arrow in the diagram). In one embodiment, this sub-step is performed simultaneously with the actuation of the pull rope 5, which pulls the trolley 8 closest to the locking trolley 8 to slide on the track 1. The trolley 8 closest to the locking trolley 8 is then locked onto the track 1. This procedure is repeated for all trolleys 8 within the tunnel 103.

[0067] According to an alternative embodiment, a predetermined sag is applied to cable span 100 as it moves forward along tunnel 103. Sag device 14 ( Figure 5The descent device 14 is located within tunnel 103, at a distance from the connection point between the trolley 8 and track 1 at tunnel entrance 106, said distance being at least substantially equal to half the length L. The descent device 14 includes a push arm 15, which, in its standby state, is vertically positioned above the cable span 100. When the center of the cable section contained between the two trolleys (which move forward on track 1 when pulled by the pull rope 5) reaches substantially below the push arm 15, the push arm 15 is lowered to push the cable downward, thereby achieving a predetermined sag. The descent operation ends when the cable span 100 within tunnel 103 has sagped as desired.

[0068] When the sag cable span 100 moves along the track 1 by tension applied to the trolley 8 that carries it, the sag is maintained during deployment.

[0069] At the end of any of the optional descent procedures, once the cable head 108 reaches the end point 102, at least some or all of the trolleys 8 within the tunnel 103 can be statically locked onto the track 1, as explained above.

[0070] The installation method disclosed herein is considered complete when the cable head reaches the predetermined end point outside the tunnel. Subsequently, the individual cable span thus installed can be connected to the power grid via, for example, the first and second joint chambers mentioned above.

[0071] Figure 4 The image depicts the final configuration of each individual cable span 100 installed according to this disclosure. In this embodiment, each individual cable span 100 is supported by a corresponding rail 1 and connected to the rail 1 via a plurality of trolleys 8 for cable deployment. Thus, according to the method of this disclosure, the trolleys 8 and the rails 1 are used to install and support the individual cable span 100 at the end of the installation.

Claims

1. A method for installing a single power cable span (100) in a tunnel (103) having a tunnel entrance (106) and a tunnel exit (107), the method comprising the steps of: The cable head (108) of the single power cable span (100) is positioned near the tunnel entrance (106); The single power cable span (100) is laid in the tunnel (103) and passes through the tunnel exit (107). in, The step of laying the single power cable span (100) in the tunnel (103) includes repeating the following sub-steps until the cable head (108) reaches the end point (102) outside the tunnel (103): At the tunnel entrance (106), a trolley (8) is slidably connected on a track (1) that extends longitudinally along the tunnel (103) between the tunnel entrance (106) and the tunnel exit (107). Connect the trolley (8) to the pull rope (5) and the single power cable span (100); The trolley (8) is moved along the track (1) by pulling the rope (5); Connect another vehicle (8) after a predetermined length (L); At the tunnel exit (107), the trolley (8) is disconnected from the pull rope (5) and the single power cable span (100), and the trolley (8) is removed from the track (1); When the cable head (108) reaches the end point (102), at least the trolley (8) closest to the tunnel exit (107) is locked on the track (1) inside the tunnel (103).

2. The method according to claim 1, wherein, At least a number of trolleys (8) are locked on the track (1) inside the tunnel (103).

3. The method according to claim 1 further includes the step of dragging the cable head (108) to the endpoint (102) by an auxiliary pull rope when the cable head (108) reaches a predetermined position outside the tunnel (103) and is disconnected from the trolley (8).

4. The method of claim 1, further comprising the step of imparting a predetermined sag to a single power cable span (100) when the cable head (108) reaches the end point (102), the step comprising repeating the following sub-steps until each cable section between two successive trolleys (8) has a predetermined sag: Lock the trolley (8) closest to the tunnel exit (107) onto the track (1) inside the tunnel (103); Disconnect the trolley (8) closest to the tunnel exit (107) from the pull rope (5); and The remaining trolleys (8) that can still slide on the track (1) are pulled by the pull rope (5) until the cable section between all the trolleys in the tunnel (103) is given the predetermined sag.

5. The method according to claim 4, comprising the sub-step of connecting at least one additional trolley (8) to the single power cable span (100) and the pull rope (5) at the tunnel entrance (106) while pulling the remaining trolleys (8) that can still slide on the track (1).

6. The method of claim 1, further comprising the step of imparting a predetermined sag to the individual power cable span (100) while moving forward along the tunnel (103), the step comprising repeating the following sub-steps until each cable section between two successive trolleys (8) within the tunnel (103) has a predetermined sag: A descent device (14) including a push arm (15) is provided near the tunnel entrance (106); Lower the push arm (15) to push the cable portion contained between the two trolleys (8) at its center and obtain the predetermined sag.

7. An apparatus for installing a single power cable span (100) in a tunnel (103), comprising: At least one track (1) is fixedly installed longitudinally in the tunnel (103); The pulling device (3) and the pull rope (5) driven by the pulling device (3); and A plurality of trolleys (8) slidably coupled to the at least one track (1), each of the trolleys (8) including means (10) for releasably connecting the trolley (8) to the pull rope (5) and means (11) for releasably connecting the trolley (8) to the single power cable span (100), The means (10) for releasably connecting the trolley (8) to the pull rope (5) and the means (11) for releasably connecting the trolley (8) to the single power cable span (100) include clamps having corresponding halves (12, 13).

8. The device according to claim 7, comprising an auxiliary pulling device and an auxiliary pulling rope, the auxiliary pulling rope being driven by the auxiliary pulling device and connectable to the cable head (108) of the individual power cable span (100).

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