JPH05316629A - Subaqueous cable laying section - Google Patents

Abstract

PURPOSE:To provide a subaqueous cable laying section by which a subaqueous cable is not damaged, deformed, etc., by an external force, such as tension, compressive force, etc. CONSTITUTION:The section is constituted of a protective tube 8 which is laid between an on-water floating facility 1 and water bottom S and provided with a relaxed section 9 of which part is made to float by means of a plurality of distributed buoys 6, subaqueous cable 2 housed in the tube 8 with a gap, and liquid 7 which is put in the tube 8 so as to fill up the gap between the tube 8 and cable 2 and the tube 8 is formed in such a way that the tube 8 can have stronger flexural rigidity, higher allowable tension, and larger allowable minimum bending radius than the cable 2 has and flexibility and the liquid 7 can have a density of 0.8-1.2, and then, the specific gravity of the cable 2 can become 0.8-1.2 times as large as that of the liquid 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater cable laying portion for laying an underwater cable in a protective tube filled with a liquid.

[0002]

2. Description of the Related Art FIGS. 2A to 2C are explanatory views showing a conventional underwater cable laying portion. When an underwater cable 2 which is a power cable or a control cable for connecting the floating equipment 1 on the water and a fixing device (not shown) for the water bottom or a composite cable related to the combination is suspended in water, As the floating equipment 1 moves, forces such as tension, bending moment, and twisting torque are applied to the cable 2.

Therefore, in order to absorb the movement and swing of the floating equipment 1 moored by the mooring lines 3, it is necessary to give the cable laying shape a degree of freedom. In addition to the simple suspension shape as shown in Fig. 2, a buoyant body such as an intermediate buoy 4 and a dispersion buoy 6 is attached to a part of the underwater cable 2 to lift it up as shown in Figs. 2 (B) and (C). A laying shape provided with a relaxing portion (the former is called a Ray S-type and the latter is called a Ray-wave type) has also been put to practical use. In FIG. 2B, a mid-arch mooring chain 5 is provided near the intermediate buoy 4 to moor the underwater cable 2.

Further, the underwater cable is, for example, a power supply cable or a control cable, or a composite cable in which these cables are combined, on which an armored wire for axial force reinforcement is wound, and a watertightness is provided outside thereof. The protective layer is covered.

[0005]

However, when the movement of the floating equipment is large, in order to suppress the force acting on the underwater cable within a range that does not exceed the allowable tension and the bending moment of the cable, It is necessary to enlarge the loosened portion of the laid shape. However, when the cable laying space is limited, it is difficult to secure a sufficient movement range, and local bending concentration and excessive tension are likely to occur. Further, when a plurality of underwater cables or other suspended installations are simultaneously laid on the underwater cable, there is a risk of injury due to mutual contact.

As means for solving the above-mentioned problems, a method of attaching a protector for controlling bending to the underwater cable body and a method of covering the entire length of the underwater cable with a flexible protective tube can be considered, but in the former case, Since the external force acting on the protective equipment is directly transmitted to the cable body supporting the protective equipment, the tension generated in the underwater cable becomes large, and it is difficult to evaluate the durability of the protective equipment. In the latter case, the external force applied to the protective tube can be avoided from being directly transmitted to the cable by separately supporting the end portions of the protective tube and the underwater cable, but the cable is self-weighted inside the protective tube. Due to, the tension at the upper end of the cable increases and the compressive force is applied to the lower end,
Local deformation occurs in the cable.

Furthermore, the friction between the inner surface of the protective tube and the surface of the underwater cable causes damage to the cable coating and local increase in the cable tension at the bent portion of the protective tube, which is to be applied to applications requiring a long service life. I can't.

[0008]

The present invention has been made in view of the above circumstances, and an object thereof is to provide an underwater cable laying portion in which an underwater cable is not damaged or deformed by an external force such as tension or compression force.

[0009]

[Means for Solving the Problems] A protective tube laid between floating equipment on the water and the bottom of the water, an underwater cable accommodated in the protective tube with a gap, and a gap between the protective tube and the underwater cable are filled. As described above, the protection tube is larger in bending rigidity, allowable tension and allowable minimum bending diameter than the cable, has flexibility, and has a liquid density of 0.8. .About.1.2, the specific gravity of the underwater cable with respect to the liquid is in the range of 0.8 to 1.2.

[0010]

According to the submerged cable laying portion of the present invention, the underwater cable receives a buoyancy force substantially equal to the weight of the cable due to the liquid filled in the protective tube, so that the weight of the cable in the liquid in the protective tube is reduced, and thus the cable is reduced. Damage and local tension on the cable can be prevented, and even if an external force is applied to the cable, the external force is received by the protective tube, and the external force is not applied to the cable, extending the service life of the underwater cable. be able to.

[0011]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 (A) and 1 (B). FIG. 1A is an explanatory view showing an embodiment of the present invention, and the laying shape of the underwater cable laying portion is the same as that shown in FIG. 2C. As shown in FIG. 1 (B), the laying portion of the present invention is such that the underwater cable 2 is loosely accommodated in the flexible protection tube 8 with a gap, and the protection tube is further filled with the gap. 8 is filled with the liquid 7 and the protective tube 8 is laid by the floating equipment 1 on the water moored by the mooring lines 3 and the relaxing portion 9 partially floated by the plurality of dispersion buoys 6 between the water bottom S. It is configured by

The protective tube 8 must have a flexural rigidity and an allowable minimum bend diameter larger than those of the cable 2 because it is necessary to prevent external force from being applied to the underwater cable 2 and prevent deformation due to the action of external force. To be done. Moreover, in order to make the allowable limit in the extreme state larger than that laid with only the underwater cable 2, the allowable tension of the protection tube 8 is larger than the cable 2.

The liquid 7 filled in the protective tube 8 is generally water or seawater, but it is also possible to use insulating oil, antifreeze liquid or the like as required. However, the density of the internal liquid is set in the range of 0.8 to 1.2 in order to reduce the change in the total weight in the liquid and obtain a stable laying shape.
That is, if the density of the liquid is less than 0.8 or less,
Since the total weight of the protection tube 8 filled with the liquid 7 in water is too light, it is difficult to maintain a stable laying shape against external force such as tidal current. Further, if the liquid density is larger than 1.2, the protection tube Since the weight of 8 is too heavy, the tension generated at the upper end of the protection tube 8 is increased, and the application limit of underwater cable laying is reduced.

The underwater cable 2 is an electric power or control cable or a composite cable of these, which is wound with an FRP wire to reinforce the axial force and is armored, and a watertight protective sheath is provided in the outermost layer. Therefore, it is desirable to minimize the influence on the overall installation shape. For that purpose, it is appropriate that the specific gravity of the cable with respect to the liquid 7 filled in the protective tube 8 is 0.8 to 1.2. As a result, a buoyancy force substantially equal to the weight of the cable acts on the underwater cable 2 inside the protection tube 8, so that the tension of the cable 2 is reduced, and the contact surface pressure with the inner surface of the protection tube 8 is also reduced, resulting from friction and wear. It is possible to prevent adverse effects on the underwater cable 2. Furthermore, by making the bending rigidity of the cable smaller than that of the protective tube 8, a cable having a laid shape along the curvature of the protective tube 8 can be obtained.

The specific gravity of the underwater cable 2 is 0.8.
When the specific gravity is smaller, the strength of the cable is reduced and it cannot be put to practical use, and it is difficult to manufacture a cable having a low specific gravity. When the specific gravity is more than 1.2, this drawback is solved, but the tension of the cable is large. In addition, there is a problem that the contact surface pressure with the protective tube 8 becomes large and the cable is worn or locally bent and damaged.

In order to form the laying portion of the present invention, the protective tube 8 is hung in advance between the floating equipment 1 on the water and the water bottom S so as to have the relaxing portion 9 in the middle, and thereafter, The underwater cable 2 may be drawn into the protection tube 8 to be stored, or the underwater cable 2 may be stored in the protection tube 8 in a factory or the like in advance, and the protection tube 8 storing this cable may be a floating type. It may be installed between the facility 1 and the water bottom S. The liquid 7 may be filled in the protection tube 8 in advance before the underwater cable 2 is stored in the protection tube 8.
The underwater cable 2 may be stored in the pipe 8 and then filled in the pipe 8. In either case, the underwater cable 2 is filled so as to fill the gap between the protection pipe 8 and the underwater cable 2.

When the underwater cable 2 is stored in the protection tube 8 in a factory or the like, the protection tube 8 manufactured in advance is used.
Is prepared and the underwater cable 2 is drawn into the protection tube 8 later, or the underwater cable 2 is drawn into the protection tube 8 at the same time when the protection tube 8 is manufactured. The underwater cable 2 is housed in the protection tube 8 by forming the protection tube 8 by forming the protection tube 8 so as to cover the outer circumference of the underwater cable 2 while vertically attaching the tube material. You may do it. When the underwater cable 2 is housed in the protective tube 8 by drawing the underwater cable 2 at the same time as manufacturing the protective tube 8 or by vertically attaching the protective tube 8 to the underwater cable 2, the liquid 7 is protected by the protective tube 8. 8
After the underwater cable 2 is housed therein, it is necessary to fill the inside of the pipe 8.

In the laying portion, the type in which the dispersion buoy 6 is used as the relaxing portion 9 has been described as an example.
A type using an intermediate buoy as shown in FIG. 2B may be used. It is preferable to have the relaxing portion 9, but depending on the conditions such as the depth of the water and the speed of the tidal current, it may be a laid shape without the relaxing portion 9 as shown in FIG. 2 (A). It is not an essential requirement of the invention.

[0019]

As described above, according to the underwater cable laying portion of the present invention, the protective pipe laid between the floating equipment on the water and the bottom of the water, and the underwater stored with a gap in the protective pipe. It is composed of a cable and a liquid filled in the protective tube so as to fill the gap between the protective tube and the underwater cable, and the protective tube has a flexural rigidity, an allowable tension and an allowable minimum bending diameter larger than those of the cable, and is flexible. Since the density of the liquid is 0.8 to 1.2 and the specific gravity of the underwater cable with respect to the liquid is in the range of 0.8 to 1.2, the weight in the liquid in the protective tube of the underwater cable Can be prevented, the local tension of the cable, the occurrence of damage and deformation can be prevented, and the protection tube protects the underwater cable even when external force acts, so the service life of the underwater cable can be extended. ..

[Brief description of drawings]

FIG. 1A is an explanatory diagram showing an embodiment of the present invention.

FIG. 1 (B) is a cross-sectional view taken along line XX of FIG. 1 (A).

2 (A) to (C) are explanatory views showing a conventional underwater cable laying portion.

[Explanation of symbols]

 1 Floating type equipment 2 Underwater cable 6 Dispersion buoy 7 Liquid 8 Protection tube 9 Relaxation part

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[Procedure amendment]

[Submission date] December 9, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art FIGS. 2A to 2C are explanatory views showing a conventional underwater cable laying portion. An underwater cable 2 which is a power cable , a communication (including optical communication) cable or a control cable for connecting the floating equipment 1 on the water and a fixing device (not shown) on the water bottom, or a composite cable related to the combination thereof. When the cable 2 is suspended and installed, forces such as tension, bending moment, and torsion torque are applied to the cable 2 as the floating equipment 1 moves.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

Further, the underwater cable is, for example, a power supply cable , a communication (including optical communication) cable, a control cable, or a composite cable in which these cables are combined, on which an armored wire for axial force reinforcement is provided. Is wound and the outside is covered with a watertight protective layer.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The underwater cable 2 is used for power , communication (optical
(Including communication) or control cable or a composite cable of these and wrapped with FRP wire to reinforce the axial force and armored, with a watertight protective sheath on the outermost layer is used. It is desirable to minimize the impact. For that purpose, it is appropriate that the specific gravity of the cable with respect to the liquid 7 filled in the protective tube 8 is 0.8 to 1.2. As a result, a buoyancy force substantially equal to the weight of the cable acts on the underwater cable 2 inside the protection tube 8, so that the tension of the cable 2 is reduced, and the contact surface pressure with the inner surface of the protection tube 8 is also reduced, resulting from friction and wear. It is possible to prevent adverse effects on the underwater cable 2. Further, by making the bending rigidity of the cable smaller than that of the protective tube 8, a cable having a laid shape along the curvature of the protective tube 8 can be obtained.

Front page continuation (72) Inventor Shigeru Ishikura 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A protective pipe laid between floating equipment on the water and the bottom of the water, an underwater cable accommodated with a gap in the protective pipe, and a protective pipe inside so as to fill the gap between the protective pipe and the underwater cable. The protective tube is larger in bending rigidity, allowable tension and allowable minimum bending diameter than the cable, has flexibility, and has a liquid density of 0.8.
The specific gravity of the underwater cable with respect to the liquid is in the range of 0.8 to 1.2.