JP2002100244A - Doubly armored submarine cable and its laying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a doubly armored submarine cable suitable long laying section and in a sea region where the tidal current is fast. SOLUTION: The outer periphery of a cable body 2 is doubly shielded with an inner armor body 3 and an outer armor body 4. The inner armor body 3 is formed with FRP wires 16, and the outer armor body 4 is formed with iron wires 19. The inner armor body 3 formed of the FRP wires 16 and the outer armor body 4 formed of the iron wires 19 are twisted in the same winding direction. The twisting pitch of the FRP wires 16 forming the inner armor body 3 made larger than the twisting pitch of the iron wires 19 forming the outer armor body 4 is set to be less than 30 times the layer core diameter of the inner armor body 3 formed with the FRP wires 16. An anti-corrosive layer 23 is formed around the outer armor body 4, and a friction resistance reduction layer 24 is formed around the anti-corrosive layer 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a long laying section,
The present invention relates to a double armored submarine cable suitable for laying in a sea area where tides are fast, and a method of laying the same.

[0002]

2. Description of the Related Art As a double-armored submarine cable, both an inner armor and an outer armor are double-armored using a plurality of iron wires, and the inner armor and the outer armor are used. In general, a structure is provided with the same twist pitch length as that of the above and a reverse twist.

However, in the case of a double armored submarine cable in which both the inner armor and outer armor are armored with iron wire, the weight per unit length becomes too large and the installation facilities are large. There is a problem that the installation cost increases,
Also, as the water depth becomes deeper, the problem is increased and the installation becomes more difficult, the installation speed is reduced, the installation takes more time, and the installation cost is increased.

In order to solve such a problem, a double armored submarine cable having a structure in which an inner armored body and an outer armored body are provided by FRP wires at the same twist pitch length and oppositely twisted is used. Is also considered.

However, in the double armored submarine cable in which both the inner armor and the outer armor are made of the FRP wire, the weight per unit length is too light, and the double armored cable is damaged by waves and the like. The armored submarine cable sways on the seabed, and the FRP wire, which has lower abrasion resistance than iron wire, is damaged early by friction with rocks and shells on the seabed, and the function of the outer armored body is reduced or lost early. There is a problem.

[0006] A double-armored submarine cable in which the inner armor is made of iron wire and the outer armor is made of FRP wire has been proposed (Japanese Utility Model Laid-Open No. 60-73116).

In the double-armed submarine cable having such a structure, since the inner armor is made of iron wire, the weight per unit length increases, and the double-armored submarine cable is submerged due to waves and the like. Swinging can be suppressed more than that of the double FRP armor. Further, there is an advantage that the inner armor made of iron wire can be protected to some extent by the outer armor made of FRP wire.

However, in the double armored submarine cable disclosed in Japanese Utility Model Application Laid-Open No. 60-73116, the outermost layer of the armored body is constituted by the FRP wire, so When rocking on the sea floor, each FRP line is damaged early by friction with the rocks and shells on the sea floor,
There is a problem that the function of the armored body constituted by the FRP wire is reduced or lost at an early stage.

In order to solve such problems, a double armored submarine cable in which the inner armor is formed of FRP wire and the outer armor is formed of iron wire has been proposed. According to the double armored submarine cable having such a structure, since the outer armored body is made of iron wire, the function of the armored body is maintained even if the double armored submarine cable swings on the seabed due to waves or the like. It is possible to prevent early decline or loss. Also, if the iron wire that constitutes the outer armor is broken due to corrosion or friction during use, the tension at the time of collecting this double armored submarine cable is used to construct the inner armor. The burden of the FRP line makes it possible to easily carry out the collection operation.

[0010] Further, in the case of laying such a double-armed submarine cable, for example, in a shallow sea section having a water depth of 5 m or less, such as a land-rise section, a laying boat loaded with the double-armored submarine cable is used. Stop on the sea near the land, pull out the double armored submarine cable from the laid ship, float it on a floating body attached at a predetermined interval, pull it on the land side, pull it up on the land and fix it at a fixed place, In this state, the floating body was sequentially removed and the double-armored submarine cable was sunk to the seabed. Thereafter, in a deep sea section, the double-armored submarine cable was extended out and laid under the seabed as it was in the deep sea section while moving the laying ship. .

[0011]

However, in the conventional double armored submarine cable in which the inner armor is formed of FRP wire and the outer armor is formed of iron wire, the inner armor and the outer armor are provided. Since both are constructed with the same standard twist pitch, when laying in a deep water area where sea currents are fast, etc., the tension acting on the double-armored submarine cable tends to fluctuate, and There is a problem that a kink is easily generated in the double armored submarine cable. Also, even after being laid on the seabed, the double armored submarine cable is liable to sway due to the tidal current or the wave of a typhoon, causing the cable to sway, causing tension and relaxation to occur in the cable. However, there is a problem that kink is easily generated.

When laying a double-armed submarine cable on the seabed, the double-armored submarine cable is laterally placed in a cylindrical container or a cylindrical frame on a horizontally oriented turntable fitted to a laying ship. A method of laying a double-armored submarine cable supplied and wound laterally around the rotation axis of the turntable while rotating the turntable (this is called a turntable laying method); The double-armored submarine cable was dropped into the flat take-up space from above, and the double-armored submarine cable was crawled and wound out into the sea via a turret-shaped cable guide fitted to a laying ship, and then submerged. There is a method of laying (this is referred to as a tower laying method). However, in the turntable installation method, the double armored submarine cable is unwound at a high speed because the double armored submarine cable is unwound into the sea while rotating the turntable that winds the heavy double armored submarine cable. It is difficult to run the cable underwater. In order to lay in the sea area where the laying section is long and the tide is fast, it is necessary to lay the double armored submarine cable at a stretch around the time of the tide, and for this purpose it is necessary to increase the laying speed, The turntable installation method is not appropriate because the installation speed is slow, and it is necessary to adopt a tower installation method. In order to adopt the turret laying method, it is necessary to wrap the double armored submarine cable around the laying ship, but in general, the double armored submarine cable consists of the inner armor and the outer armored body in reverse twist. Therefore, if you try to wind it on a laying ship, the armor of either layer will be tightened, the cable winding radius will be large, and a large laying ship will be required, and the laying cost will be high. There is a problem.

Further, when the seabed is rock or coral reef in a shallow sea section, the double armored submarine cable is used to prevent damage due to repeated movement on the seabed due to the waves of the double armored submarine cable and damage to the coral reef. The cable is laid by being drawn into a pipeline laid on the sea floor. However,
In this case, when the double-armored submarine cable is drawn into the pipeline, the coal tar on the outer surface of the anticorrosion layer moves in contact with the inner surface of the pipeline, and the frictional resistance becomes extremely large. There was a problem that it was not easy to lay the inside.

An object of the present invention is to provide a double armored submarine cable suitable for laying in a sea area where the laying section is long and the tidal current is fast, and a laying method thereof.

Another object of the present invention is to provide a double armored submarine cable which can be laid quickly while preventing the occurrence of kinks, and a method of laying the same.

Another object of the present invention is to provide a double-armored submarine cable capable of laying in a pipeline in a shallow sea section with a reduced frictional resistance, and a method of laying the same.

[0017]

According to the present invention, the outer periphery of a cable body is double-armored with an inner armor and an outer armor,
In a double armored submarine cable in which an anticorrosion layer is provided on the outer periphery of an outer armored body, the inner armored body is constituted by FRP wire, the outer armored body is constituted by iron wire, and the inner armored body is constituted by FRP wire. The outer armored body consisting of the body and the iron wire is constituted by the same direction twist with the same winding direction, the twist pitch of the FRP wire constituting the inner armored body is longer than the twist pitch of the iron wire constituting the outer armored body, It is set to be 30 times or less the core diameter of the inner armor made of FRP wire, and is characterized in that a frictional resistance reducing layer is provided on the outer periphery of the anticorrosion layer.

In the present invention, the layer core diameter is opposite from the center of the layer thickness at a certain position in the circumferential direction of the target armoring body (or the center of the armoring wire at that position) through the center of the cable body. Side to the center of the layer thickness at the position of the armor (or the center of the armoring wire at that position).

In such a double armored submarine cable, the twist pitch of the FRP wire forming the inner armor is longer than the twist pitch of the iron wire forming the outer armor, and the inner armor made of the FRP wire is used. Since it is set to be 30 times or less of the layer core diameter of the body, the FRP wire is prevented from laughing greatly due to the tension fluctuation acting on the cable when the double armored submarine cable is laid, and the iron wire is used to suppress it. And FR
Using the repulsive force to spread outside the P line, trying to eliminate suddenly the laugh of the iron wire, that is, the double armored submarine cable will be twisted sharply in the direction in which the twist of the outer armor tightens. And the occurrence of kinks in the double-armored submarine cable during installation can be prevented.

Further, in the double armored submarine cable, as described above, kink hardly occurs in the double armored submarine cable, and the winding direction of the inner armored body and the outer armored body are made the same. Since it is constructed by the same direction twist, it can be pulled out at high speed through the turret-shaped cable guide on the laying ship and laid on the seabed by the turret laying method, so that the laying section is long and the tidal current is fast Even in the case of laying in the sea area, the laying can be performed at once, mainly at the time of the tide stop, and the laying cost can be reduced.

In addition, when the tidal current is fast after being laid on the seabed, or under the influence of waves due to a typhoon, the double-armored submarine cable swings, and tension fluctuation and relaxation action repeatedly occur in the double-armored submarine cable. However, since the double armored submarine cable is less likely to cause a kink, long-term reliability and stability of the double armored submarine cable can be ensured.

Further, according to the double-armored submarine cable, the cable winding radius of the laying ship can be made relatively small, so that there is no need to use a large laying ship and the laying cost is further reduced. be able to.

In this double-armored submarine cable, the twist pitch of the FRP wire of the inner armor is set to 30 times or less the layer core diameter of the inner armor. It is possible to prevent the taking diameter from becoming unrealistically large.

Further, in this double armored submarine cable,
Since the friction resistance reduction layer is provided on the outer periphery of the anticorrosion layer,
The increase in friction resistance due to the anticorrosion layer when the cable is drawn and laid in the pipeline in the shallow sea section can be prevented by the friction resistance reducing layer provided on the surface thereof, and the cable can be easily laid into the pipeline.

The present invention also relates to a method for laying a double armored submarine cable in which a double armored submarine cable loaded on a laid ship is extended from the laid ship and laid on the seabed. The armor is composed of FRP wire, the outer armor is composed of iron wire, the inner armor composed of FRP wire and the outer armor composed of iron wire are composed of the same direction twist with the same winding direction, The twist pitch of the FRP wire forming the inner armor is longer than the twist pitch of the iron wire forming the outer armor, and is set to 30 times or less the layer core diameter of the inner armor made of the FRP wire. A double-armored submarine cable is wrapped around a laid ship using a structure in which a frictional resistance reducing layer is provided on the outer periphery of the armor with an anticorrosion layer interposed, and the double-armored double armor is Submarine cable laid on ship And feeding the sea through a form cable guide, in shallow water section is laid by pulling the conduit seabed,
It is characterized by laying as it is in the deep sea section.

In such a method of laying a double-armed submarine cable, the twist pitch of the FRP wire forming the inner armor of the double-armed submarine cable is smaller than the twist pitch of the iron wire forming the outer armor. Because the length is set to be 30 times or less the layer core diameter of the inner armor made of the FRP wire, the FRP wire will laugh greatly due to the tension fluctuation acting on the cable when the double armored submarine cable is laid. In addition to having the wire act to suppress the movement of the wire, and using the repulsive force to spread to the outside of the FRP wire, to try to eliminate the laugh of the wire sharply, that is, twisting the outer armor It is possible to prevent the double-armored submarine cable from suddenly twisting in the direction in which the cable is tightened, and to prevent kink from being generated in the double-armored submarine cable during installation.

Further, in the double armored submarine cable, as described above, kink hardly occurs in the double armored submarine cable, and the inner armored body and the outer armored body are wound in the same direction. Since it is constructed by the same direction twist, it can be pulled out at high speed through the turret-shaped cable guide on the laying ship and laid on the seabed by the turret laying method, so that the laying section is long and the tidal current is fast Even in the case of laying in the sea area, the laying can be performed at once, mainly at the time of the tide stop, and the laying cost can be reduced.

In addition, when the tidal current is fast after being laid on the seabed or the waves due to a typhoon, the double armored submarine cable swings, and the double armored submarine cable repeatedly undergoes tension fluctuation and relaxation action. However, since the double armored submarine cable is less likely to cause a kink, long-term reliability and stability of the double armored submarine cable can be ensured.

Further, according to the double-armored submarine cable, the cable winding radius of the laying ship can be made relatively small, so that there is no need to use a large laying ship and the laying cost is further reduced. be able to.

According to this double-armored submarine cable, the twist pitch of the FRP wire of the inner armor is set to 30 times or less the layer core diameter of the inner armor, so that It is possible to prevent the cable winding diameter from becoming unrealistically large.

Further, in this double armored submarine cable,
Since the friction resistance reduction layer is provided on the outer periphery of the anticorrosion layer,
The increase in friction resistance due to the anticorrosion layer when the cable is drawn and laid in the pipeline in the shallow sea section can be prevented by the friction resistance reducing layer provided on the surface thereof, and the cable can be easily laid into the pipeline.

Further, in the method for laying a double-armed submarine cable according to the present invention, the coiling of a double-armored submarine cable to a laying ship may be performed in a direction in which both twists of the inner armor and the outer armor are loosened. It is characterized in that it is performed in such a way that

[0033] In this way, when the laying boat is clogged and housed, the tightening force of the double armored body on the outer periphery of the double armored submarine cable is not applied, and the coiling of the tuna winding on the laid boat is facilitated. Can be performed.

Further, the method for laying a double-armored submarine cable according to the present invention is characterized in that the pipeline is drawn into and buried in a horizontal hole drilled in the seabed.

In this way, when the pipeline is drawn and buried in the horizontal hole drilled in the seabed, even if there is a coral reef or the like on the seabed, the double armored submarine cable can be laid without damaging it. Can be performed.

[0036]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a double-armored submarine cable according to the present invention.

In the double-armored submarine cable 1 of this embodiment, the outer periphery of the cable body 2 is double-armored with the inner armor 3 and the outer armor 4.

In the cable body 2, a three-phase power line 5, an optical fiber communication line 6, and an interposition 7 made of a plastic string are twisted together, and the optical fiber communication line 6 is accommodated in a fan-shaped groove formed between the power lines 5. At the same time, after each fan-shaped groove is filled with the interposition 7, a winding layer 8 is provided on the outer periphery. Each power line 5 has an inner semiconductive layer 10, an insulator 11, an outer semiconductive layer 12,
3, a layer structure in which polyethylene termite layers 14 are sequentially provided.

The inner armored body 3 is a seat floor 1 made of a plastic string provided on the outer periphery of the winding layer 8 of the cable body 2.
5 are provided. The inner armored body 3 is formed by spirally winding a number of FRP wires 16. Each FR
The outer circumference of each of the P wires 16 is coated with a high-density polyethylene 17.

The outer armored body 4 is provided via a seat 18 made of a plastic string provided on the outer periphery of the inner armored body 3. The outer armored body 4 is formed by spirally winding a large number of galvanized iron wires 19. Although not shown, the surface of each galvanized iron wire 19 is subjected to anticorrosion treatment using coal tar.

The inner armored body 3 composed of the FRP wire 16 and the outer armored body 4 composed of the iron wire 19 are formed by twisting in the same direction with the same winding direction. The twist pitch of the FRP wire 16 constituting the inner armored body 3 is longer than the twist pitch of the iron wire 19 constituting the outer armored body 4,
It is set to 30 times or less the layer core diameter of the inner armored body 3 made of. In this example, the twist pitch of the FRP wire 16 is
It is preferably 16 to 25 times the layer core diameter of the inner armored body 3 composed of the wire 16, and most preferably 20 times the layer core diameter. The twist pitch of the iron wire 19 is set to a standard twist pitch, that is, 10 to 13 times the core diameter of the outer armored body 4 made of the iron wire 19. Therefore, the twist pitch of the FRP wire 16 is set longer than the standard twist pitch of the iron wire 19. Also, FRP
The upper limit of the twist pitch of the wire 16 is 30 times the layer core diameter of the inner armored body 3 due to the practical winding limit when the double-armed submarine cable 1 is towed around the laid ship.

Coal tar 20 is applied to the outer periphery of the outer armored body 4 composed of the iron wire 19, a plastic string 21 is wound around the outer periphery, and coal tar 22 is applied again to the outer periphery. An anticorrosion layer 23 is formed. A frictional resistance reducing layer 24 is provided on the outer periphery of the anticorrosion layer 23 by extrusion coating of a polyethylene sheath or winding of canvas.

It is conceivable to use an Irish armor in which the twisting pitch of the iron wire 19 constituting the outer armoring body 4 is smaller than the standard twisting pitch. Is unfavorably increased in flexibility, and kinks are likely to occur due to fluctuations in tension.

In this example, the twist pitch of the FRP wire 16 is
Since the length is longer than the twist pitch of the iron wire 19 constituting the outer armored body 4, the double armored submarine cable 1 is kinked (less than the allowable bending radius of the cable) during and after installation by utilizing the repulsive force of the FRP wire 16. Local annular torsion) can be prevented from occurring. That is, if tension is applied when the double-armored submarine cable 1 is laid, the inner armored body 3 and the outer armored body 4 rotate in a direction in which the twist is loosened. When the double armored submarine cable 1 is twisted in a direction in which the twist of the inner and outer armored bodies is tightened, a ring is formed, and tension is applied again to the double armored submarine cable 1 so that the ring is contracted and the ring is shrunk. Kink occurs.
More specifically, each of the armored bodies 3 and 4 constituting the inner and outer armored bodies loosened by the tension is laughed and spread outward due to the sudden release of the tension, and the outer diameter of each of the armored bodies 3 and 4 is increased. In order to absorb the laughter of each of the armored bodies 3 and 4 by reducing the outer diameter to the original state, the double armored submarine cable 1 is twisted in a direction in which the twist of the inner and outer armored bodies is tightened. When a ring having a size is formed and the tension is applied to the double-armored submarine cable 1 again, the ring is contracted without being unraveled, so that a local ring is formed.
That is, kink occurs. The laughter of the armor bodies 3 and 4 increases as the twist pitch increases.

Therefore, in this example, the twist pitch of the FRP wire 16 forming the inner armored body 3 is made longer than the twist pitch of the iron wire 19 forming the outer armored body 4, so that the FRP wire 16 tends to laugh greatly. Is controlled by the iron wire 19, and the laugh of the iron wire 19 is suddenly eliminated by using the repulsive force of spreading outside the FRP wire 16, that is, the outer armor body 4 The double-armored submarine cable 1 can be prevented from suddenly twisting (braking) in the direction in which the twisting of the double-armored cable is tightened, and kink can be prevented from being generated in the double-armored submarine cable 1 during installation. In particular, when the double-armored submarine cable 1 is laid in a sea area where the tide is fast or where the water depth is deep, a large variation in the tension acting on the double-armored submarine cable 1 is likely to occur. It is valid. Even after the double-armored submarine cable 1 is laid on the sea floor, if the cable is laid in a shallow water or a sea area where the tide is fast, or if it is affected by waves due to a typhoon, the double-armored submarine cable 1 may be used. 1 oscillates, and the double-armored submarine cable 1 fluctuates in tension, so that the generation of kink can be effectively prevented.

In the double armored submarine cable 1 having the above structure, kink hardly occurs when the cable is laid on the seabed, and the inner armored body 3
The outer armored body 4 and the outer armored body 4 are formed by the same direction twist with the same winding direction, so this should be laid out at high speed through the turret type cable guide on the laying ship by the turret type laying method and laid on the seabed. Therefore, even in the sea area where the laying section is long and the tidal current is fast, the laying can be performed all at once at the time of the tide stopping, and the laying cost can be reduced. Further, since the cable winding radius in the laying ship can be made relatively small, there is no need to use a large laying ship, and the laying cost can be further reduced.

Further, in this example, the twist pitch of the FRP wire 16 is adjusted to the layer core diameter of the inner armored body 3 made of the FRP wire 16.
Since it is set to 30 times or less, it is possible to prevent the cable winding diameter of the laid ship from becoming unrealistically large.

In the double armored submarine cable 1 having such a structure, the inner armored body 3 is constituted by the FRP wire 16 and the outer armored body 4 is constituted by the iron wire 19.
Even if the double-armored submarine cable 1 swings on the seabed due to a fast tide in a shallow sea area or due to waves, etc., the outer armored body 4 constituted by the iron wire 19 resistant to abrasion causes
The FRP wire 16 constituting the inner armored body 3 can be protected.

Further, in this double armored submarine cable,
Since the frictional resistance reducing layer 24 is provided on the outer periphery of the anticorrosion layer 23, the frictional resistance is increased by the anticorrosion layer 23 when it is drawn into the pipeline in the shallow sea section and laid. 24, and can be easily drawn and laid in the pipeline.

FIGS. 2A, 2B and 3 show an embodiment of a method for laying a double-armored submarine cable according to the present invention. FIG. 2A shows a normal laying process. FIG. 2B is a side view showing a normal laying process,
FIG. 3 is a longitudinal sectional view showing a process of laying in shallow water.

In this embodiment, as shown in FIGS. 2A and 2B, the laying work is carried out by towing a laying boat 26 floating on the sea surface 25 by a towing boat 28 via a towing line 27.

The laying boat 26 is provided with a cable winding space 29. In this cable winding space 29,
A cable winding diameter regulating means 30 comprising a number of poles for regulating the inside diameter and the outside diameter of the double armored submarine cable 1 is set up along the circumferential direction. The double-armored submarine cable 1 to be laid is loaded on the cable winding space 29 by dropping the double-armored submarine cable 1 from above into a coiling shape along the cable winding diameter regulating means 30 and coiling. Keep it. As the double-armored submarine cable 1, the one having the structure described in FIG. 1 is used. When the double armored submarine cable 1 is coiled around the laying boat 26, the twists of the FRP wire 16 constituting the inner armored body 3 and the iron wire 19 constituting the outer armored body 4 are both relaxed. It is done so that it becomes.

The laying boat 26 is equipped with a tower-shaped cable guide 31 so that the uppermost portion is present on the cable winding space 29. At the end side of the tower-shaped cable guide 31, an endless pair of V-grooves for holding the double-armored submarine cable 1 on the outer periphery in order to apply a brake to the double-armored submarine cable 1 extending into the sea is provided. An automatic brake 32 composed of a belt, a manual brake 33, and a cable shooter 34 are provided.

When laying the double-armored submarine cable 1 in a shallow sea section having a water depth of 5 m or less, for example, in a land section as shown in FIG. 1m from sea bottom 35
The lower layer is excavated with a horizontal hole excavator (not shown) to form a horizontal hole 36.
And open at both ends to land 37 and sea bottom 35. A conduit 38 made of a synthetic resin or a metal such as iron is drawn into the lateral hole 36, and both ends are projected to a land 37 and a sea bottom 35. A pooling wire 39 is passed through the conduit 38 in advance.

In this state, the laid boat 26 is connected to the pipeline 3 on the seabed.
8, the double-armored submarine cable 1 coiled around the laying vessel 26 is drawn out into the sea, and the end of the cable is connected to the end of the pooling wire 39 at the connecting portion 40. Thereafter, the pooling wire 39 is taken up on the land 37 by a winch or the like, and the double-armored submarine cable 1 is connected to the conduit 3.
Pull in 8. In this case, since the frictional resistance reducing layer 24 is provided on the surface of the double-armored submarine cable 1 so as to cover the anticorrosion layer 23, the cable can be easily pulled in with reduced frictional resistance at the time of pulling in. it can.

Thus, the double-armored submarine cable 1
When the installation in the pipeline 38 on the distal end side of the
6 is pulled by a tugboat 28 along the laying route, and the double armored submarine cable 1 coiled around the laying ship 26 is
It is fed out through the turret-shaped cable guide 31, automatic brake 32, manual brake 33, and cable shooter 34 on the laying ship 26 and laid on the seabed 35.

As described above, in the method of laying the double armored submarine cable of the present embodiment, the twist pitch of the FRP wire 16 is made larger than the twist pitch of the iron wire 19 as described above.
The use of the repulsive force of the RP wire 16 can also prevent the occurrence of kink during installation.

Further, as described above, the double armored submarine cable used for laying is less likely to cause a kink, and the inner armored body 3 and the outer armored body 4 of the double armored submarine cable 1 to be laid out. Is constructed by twisting in the same direction with the same winding direction.
6 and can be laid out on the seabed 35 at high speed through the turret-shaped cable guide 31. Therefore, even in the case where the laying section is long and the tidal current is fast in the sea area, the tide stops at a stretch. It can be laid, and the laying cost can be reduced. Further, the cable winding radius at the laying boat 26 can be made relatively small, so that there is no need to use a large laying boat 26 and the laying cost can be further reduced.

In this embodiment, the twist pitch of the FRP wire 16 of the double armored submarine cable 1 to be laid is set to 30 times or less the layer core diameter of the inner armored body 3 made of the FRP wire 16. Therefore, it is possible to prevent the cable winding diameter of the laying boat 26 from becoming unrealistically large.

Further, the laying ship 2 of the double armored submarine cable 1
Coil removal for the inner armored body 3 and outer armored body 4
Is performed in such a way that both twists are loosened, so that when the cable is wound around the laying vessel 26 and accommodated, the tightening force of the double armored bodies 3 and 4 on the outer periphery of the double armored submarine cable 1 is reduced. In addition, it is possible to easily perform the coiling of the tuna winding on the laying boat 26.

In the above example, the laying boat 26 is towed by the tugboat 28, but the laying boat 26 is self-propelled by the propulsion mechanism mounted thereon without using the tugboat 28. You may.

In the above example, the double-armored submarine cable 1
Although the cable main body 2 has the structure including the optical fiber communication line 6, the cable body 2 may not include the optical fiber communication line 6.

The anticorrosion layer 23 may be formed of only the coal tar 20, and the outer periphery of the anticorrosion layer 23 may be provided with a frictional resistance reducing layer 24 by extrusion coating of a synthetic resin such as polyethylene.

[0064]

According to the double armored submarine cable and the method of laying the same according to the present invention, the twist pitch of the FRP wire forming the inner armor is longer than the twist pitch of the iron wire forming the outer armor. Since it is set to be 30 times or less the layer core diameter of the inner armor composed of the FRP wire, the FRP wire tends to laugh greatly due to the tension fluctuation acting on the cable when the double armored submarine cable is laid. Conversely, while acting to suppress with the iron wire, using the repulsive force that tries to spread outside the FRP wire, trying to suddenly eliminate the laugh of the iron wire,
That is, it is possible to suppress the double armored submarine cable from being twisted abruptly in the direction in which the twist of the outer armored body is tightened, and to prevent kink from being generated in the double armored submarine cable during installation.

Further, according to the present invention, as described above, a kink hardly occurs in the double-armored submarine cable at the time of laying, and the inner armor and the outer armor are formed by twisting in the same direction in the same winding direction. It is possible to lay this at a high speed through the turret-shaped cable guide on the laying ship and lay it on the seabed by the turret laying method, so that the laying section is long and it can be laid in the sea area where the tide is fast The installation can be performed all at once at the time when the tide stops, and the installation cost can be reduced.

In addition, when the tidal current is fast after being laid on the seabed, or under the influence of waves due to a typhoon, the double-armored submarine cable fluctuates, and the double-armored submarine cable repeatedly undergoes tension fluctuation and relaxation action. However, since the double armored submarine cable is less likely to cause a kink, long-term reliability and stability of the double armored submarine cable can be ensured.

Further, according to the present invention, the cable winding radius in the laying ship can be made relatively small, so that there is no need to use a large laying ship and the laying cost can be further reduced.

In the present invention, the twist pitch of the FRP wire is
Since it is set to 30 times or less, it is possible to prevent the cable winding diameter of the laid ship from becoming unrealistically large.

Further, in the present invention, since the frictional resistance reducing layer is provided on the outer periphery of the anticorrosion layer, the frictional resistance is increased by the anticorrosion layer at the time of drawing and laying in the pipeline in the shallow sea section. This can be prevented by the provided frictional resistance reducing layer, and the lead-in laying in the pipeline can be easily performed.

Furthermore, in the method of laying a double-armored submarine cable according to the present invention, since the conduit is buried by being drawn into the horizontal hole drilled in the seabed, even if there is a coral reef or the like on the seabed, it is damaged. It is possible to lay a double armored submarine cable without having to do so.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a double-armored submarine cable according to the present invention.

2 (A) and 2 (B) show an example of an embodiment of a method of laying a double-armored submarine cable according to the present invention, and FIG. 2 (A) is a plane showing a process of laying on a sea bottom. Figure,
(B) is a side view which shows the installation process on the sea bottom.

FIG. 3 is a longitudinal sectional view showing a method of laying a double armored submarine cable in a shallow sea area according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double armored submarine cable 2 Cable main body 3 Inner armored body 4 Outer armored body 5 Power line 6 Optical fiber communication line 7 Interposition 8 Winding layer 9 Watertight conductor 10 Inner semiconductive layer 11 Insulator 12 Outer semiconductive layer 13 Lead sheath 14 Polyethylene termite layer 15 Seat floor 16 FRP wire 17 High-density polyethylene 18 Seat floor 19 Galvanized iron wire 20 Coal tar 21 Plastic string 22 Coal tar 23 Corrosion prevention layer 24 Friction resistance reduction layer 25 Sea surface 26 Laying boat 27 Tug rope 28 Tugboat 29 Cable winding space 30 Cable winding diameter regulating means 31 Tower cable guide 32 Automatic brake 33 Manual brake 34 Cable shooter 35 Sea bottom 36 Side hole 37 Land 38 Pipe line 39 Pooling wire 40 Connection

Continued on the front page (72) Inventor Yukio Ranami 5-2-1 Makiko, Urasoe-shi, Okinawa Prefecture Inside Okinawa Electric Power Company (72) Inventor Takashi Kijima 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric F-term within the company (reference) 5G311 FA01 FA03 FB01 FB03 FC01 5G313 AA02 AB01 AB03 AC09 AC12

Claims (4)

[Claims] 1. A double-armed submarine cable in which an outer periphery of a cable body is double-armored with an inner armor and an outer armor, and a corrosion protection layer is provided on an outer periphery of the outer armor. The inner armor is made of FRP wire, the outer armor is made of iron wire, and the inner armor made of the FRP wire and the outer armor made of the iron wire are wound in the same direction. The twist pitch of the FRP wire constituting the inner armor is longer than the twist pitch of the iron wire constituting the outer armor, and the inner armor made of the FRP wire has a longer twist pitch. Layer core diameter 30
A double-armored submarine cable characterized in that the anticorrosion layer is provided with a frictional resistance reduction layer on the outer periphery of the anticorrosion layer. 2. A method of laying a double armored submarine cable in which a double armored submarine cable loaded on a laying ship is extended from the laying ship and laid on the seabed, wherein the double armored submarine cable is an inner armored cable. The body is FRP
The outer armor is composed of iron wire,
The inner armored body made of the FRP wire and the outer armored body made of the iron wire are formed by the same direction twist with the same winding direction, and the twist pitch of the FRP wire constituting the inner armored body is It is longer than the twist pitch of the iron wire constituting the outer armor, and is set to 30 times or less the layer core diameter of the inner armor made of the FRP wire, and a corrosion prevention layer is provided on the outer periphery of the outer armor. Using a structure provided with a frictional resistance reducing layer, and loading the double-armored submarine cable with the double-armored submarine cable on the laying vessel, and laying the double-armored double-layered submarine cable on the laying ship. A method of laying a double-armored submarine cable, in which the cable is unwound into the sea through a tower-shaped cable guide on board, drawn into a pipeline on the sea floor in a shallow sea section, and laid as it is in a deep sea section. 3. The winding of the double-armored submarine cable to the laying ship on the laying ship is performed in such a manner that both twists of the inner armor and the outer armor are loosened. The method for laying a double-armored submarine cable according to claim 2. 4. The method of laying a double-armored submarine cable according to claim 2, wherein the conduit is drawn into and buried in a horizontal hole drilled in the seabed.