JP2791181B2 - Submarine cable laying method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for simultaneously laying and burying a submarine cable.

(Prior Art) When laying a long submarine cable, it is important to take care that no twist remains in the cable and that the cable does not become tangled. For this reason, the cable is laid and buried on the seafloor at the same time, as shown in FIG. The cable 3 is drawn out into the water by a laying device 4 such as a drum engine or a linear engine, and dropped into a groove 8 dug into a sea bottom 7 by a digging machine 6 such as a plow by a burying device 5 towed by the laying boat 1. Is done by the way. The buried device 5 is the sea floor 7
And a grooving machine 6 projecting below the gantry 9. Reference numeral 10 denotes a tow rope for towing the buried device.

(Problems to be Solved by the Invention) In such a conventional method of simultaneously laying a submarine cable, it is difficult to finely control the ship speed, so that excessive tension remains in the buried submarine cable 3 or the cable 3 There was a risk that the underlaying device 5 would be damaged by being laid underneath. Also,
In order to withstand a huge installation tension, the cable 3 needs a tensile strength of several tons or more, and there is a drawback that a cable having a small breaking tension cannot be installed and buried at the same time.

Accordingly, an object of the present invention is to provide a submarine cable laying and simultaneous burying method capable of burying a small-diameter cable having a small breaking tension without damage, breakage, and without losing twist. It is to provide the device.

(Means for Solving the Problems) In order to achieve the above object, a method for simultaneously laying a submarine cable according to the present invention winds and mounts a cable on a cable drum fixed horizontally to a gantry, and mounts the gantry on the submarine. At the same time as moving along the surface, a groove is excavated by a groove excavator protruding from a gantry, and the submarine cables are sequentially drawn out from the cable drum from above and dropped into the grooves.

Further, the submarine cable laying and simultaneous burying device according to the present invention is a gantry provided with a trench machine which is moved along the sea bottom and protrudes into the ground to achieve the above object, and is fixed horizontally to the gantry. And a cable drum wound around a submarine cable mounted thereon.

(Operation) In the method and apparatus of the present invention, since the submarine cable is mounted on the buried apparatus itself, the cable being laid is not subjected to a tension corresponding to the sum of the underwater weight of the cable and the resistance of the tidal current, and the cable is broken. Enables the laying and burying of cables with low tension and lateral pressure resistance.

Further, in the method of the present invention, the cable is stored in the cable drum with one twist per winding, and the cable drum is turned upside down at the time of unwinding and taken up through the hole of the bell mouth. One twist per turn is returned and no twist remains in the cable.

(Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 is a side sectional view showing an embodiment of a submarine cable laying and burying apparatus according to the present invention, FIG. 2 is a partially cutaway plan view of the apparatus, and FIG. 3 shows a cable laying and burying method according to the present invention. FIG. In these figures, a submarine cable laying and simultaneous burying device (hereinafter referred to as a burying device) which is towed in the sea by the power boat 20 and moves along the seabed 7 includes a pair of left and right floats 22A and 22B and a gantry 23,
It is connected to the power boat 20 by a tow rope 10.
At the center of the lower surface of the gantry 23, a groove excavator 6 such as a plow for drilling a groove 8 for burying a cable in the sea bottom 7 is provided to protrude downward, and at the center of the upper surface, a submarine cable to be embedded in the groove 8 3
A cable drum 24 for storing the cable drum 24 is installed, and a cable drum storage 24A is further covered so as to cover the cable drum 24.
Is installed. The submarine cable 3 is wound around the cable drum 24 with one twist per turn. When the cable is unreeled, the cable drum is turned upside down to take up the hole 26 of the bell mouth 25 at the center of the cable drum. As described above, the groove 8 is drawn out from the lower rear portion of the groove excavator 6 through the cable lead-out hole 27 formed through the groove excavator 6.

The upper end opening of the hole 26 and the outer periphery of the upper end of the bell mouth 25 are chamfered with an appropriate curvature so as not to damage the submarine cable 3. A rotatable presser wheel 28 is disposed at the lower end opening of the cable lead-out hole 27 so that the submarine cable 3 is pressed against the bottom of the groove 8. At the time of winding the submarine cable 3 around the cable drum 24, as shown in FIG. 4, the submarine cable 3 wound around the cable drum 30 is drawn out and passed through a pulley 31,
A single twist may be wound around the cable drum 24 around which the collar 32 is installed at the lower part from the upper side and wound.

In the paying-out step, if the cable 3 wound once from the top is wound in once and then wound up again through the same path, no twist remains in the fed-out cable. However, in order to bury the cable, the cable 3 must be drawn out into the groove 8 excavated by the groove excavator 6. As one of the methods, there is a method in which the cable is fed downward through the hole 26 of the bell mouth. However, in this case, the laid cable is twisted. In order to prevent twisting even if it is fed downward, the following is necessary.

First, as shown in FIG. 5 (a), the collar 33 of the cable drum 24 is set on the upper surface of the cable drum 24 on which the cable has been wound. Subsequently, the cable drum 24 is turned upside down as shown in FIG. 5 (b). Further, the collar 32 is removed as shown in FIG. 5 (c), and the bell mouth 25 is attached as shown in FIG. 5 (d). Then, the cable 3 is fed downward through the hole 26 of the bell mouth 25. FIG. 6 shows a partially cutaway front view of the cable drum 24 when a bell mouth is attached. With such a structure, the hole 26 of the bell mouth 25
No twist is left even if it is fed downward through the pipe. If an optical fiber having excellent fatigue resistance such as a hermetic coat fiber is used, even if the twist remains, the fiber is less likely to be broken for a long period of time. Therefore, it is not always necessary to turn the drum upside down. As a method of laying the cable drum 24 without turning it upside down, there is a method as shown in FIG. This is because the submarine cable 3 is wound around the cable drum 24 with a single twist per turn, and when the cable is unreeled, the cable drum is not turned upside down, and the cable unwinding hole 34 is formed. Street pulley 35
And a cable outlet hole formed through the trench machine 6 through
It is drawn out from the lower rear part of the trenching machine 6 into the trench 8 via 27. At this time, the hole for cable extension
34 is chamfered with an appropriate curvature so as not to damage the submarine cable 3. Twist does not remain even if it is fed out by this method, but there is a demerit that the whole buried device becomes larger as compared with the embodiment of FIG.

The length of the submarine cable 3 wound on the cable drum 24 varies depending on the size of the drum 24, the cable diameter, etc. As an example, the cable diameter is 4 mm, the diameter of the drum 24 is 1.5 m, and the diameter of the drum 24 is 1.0m, height of drum 24 is 0.
If it is 5m, it can store cables as long as about 20km. In FIG. 1, reference numeral 29 denotes a towing hook.

In such a configuration, when the buried device 21 on which the submarine cable 3 is mounted by the power ship 20 is towed along the seabed 7, the trench machine 6 excavates the groove 8 in the seabed 7 (see FIG. 3). . Submarine cable 3 wound around cable drum 24
The wire is taken up with the advance of the embedding device 21 and is naturally pulled out from the cable lead-out hole 27, and the twist is returned once per turn, so that the wire is buried in the groove 8 without any remaining twist.
Therefore, a long cable can be extended. In the conventional laying and burying method shown in FIG.
Since a tension equivalent to the sum of the weight of the underwater and the resistance of the tidal current acts on the cable being laid, only a cable having a large breaking tension can be buried, but in the present invention, the cable is extended from the burying device 21. Thus, the action of the tension can be reduced to almost no effect, so that it is possible to lay and bury a small-diameter submarine optical cable having a small breaking tension.

Here, as shown in FIG. 3, when the buried device 21 is towed by a ship, the resistance acting between the buried device 21 and the sea bottom 7 is not constant but varies depending on the soil properties.
Indicates a so-called stick-slip phenomenon in which forward movement and stop are repeated. At this time, in order to prevent breakage of the submarine cable buried and buried at the same time, it is necessary to control the cable feeding length of the burying device 21 and the buried device movement amount to be equal.
In the conventional method shown in FIG. 8, the speed of the cable supplied to the burying device 5 is controlled in accordance with the speed of the ship to ground measured on the ship. Sensitive control of the quantity is not possible because the distance between the burying device 5 and the laying device 4 on the ship is too far,
Tension is likely to remain in the buried cable. Further, the cable is required to have a strength of several tons or more to withstand the residual tension.

On the other hand, in the simultaneous laying method according to the present invention,
Since the cable 3 mounted on the burying device 21 is naturally pulled out according to the amount of movement of the 21, the submarine optical cable having a breaking tension of about 100 kg can be buried without breaking or remaining tension. In addition, a groove width of about 1 cm is enough for embedding a small-diameter submarine optical cable with an outer diameter of several millimeters, so that drilling resistance is small. Therefore, there is an advantage that the embedding can be performed at an embedding depth of about 1 m with a small embedding apparatus having a length of about 3 m, which is slightly smaller than a conventional embedding apparatus. Also,
It is not necessary to use a laying boat for towing the burying device 21, and it is possible to use a small general-purpose boat such as a work boat.

Although the above embodiment shows the towing type burying device 21, a self-propelled laying simultaneous burying device equipped with a propulsion mechanism such as an endless track can be used, in which case the towing by the power boat 20 is unnecessary. It is.

In the above embodiment, a plow-type ditching machine is used as the ditching machine 6, but the invention is not limited to this, and a ditching machine such as a jet type or a cutter type can also be used. In addition, jet buried etc.
Even when another embedding method is used, the cable housing and feeding means are the same as described above.

(Effects of the Invention) As described above, according to the method and the apparatus for laying and burying a submarine optical cable according to the present invention, the cable drum on which the submarine cable is wound is directly mounted on the pedestal moving on the seabed. It is possible to lay and embed a small-diameter submarine cable with small breaking tension and small lateral pressure, while receiving almost no tension due to acting underwater weight and tidal resistance. In addition, since the submarine cable is wound with one twist per winding and wound up, the drum is turned upside down and then taken up at the time of unwinding, so once per winding without any power or control device. The cable can be laid and buried at the same time without twist remaining in the cable, and a highly reliable submarine line can be economically constructed.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of a submarine cable laying and burying apparatus according to the present invention, FIG. 2 is a partially cutaway plan view of the apparatus, and FIG. 3 shows a cable laying and burying method according to the present invention. FIG. 4 is a schematic view showing a method for storing a submarine cable in a cable drum, and FIGS.
(B), (c) and (d) are views showing a method of installing the cable drum in the burying device, FIG. 6 is a partially cutaway front view of the cable drum, and FIG. 7 is another example of the submarine cable laying simultaneous burying device. FIG. 8 is a side sectional view showing an embodiment, and FIG. 8 is a schematic view showing a conventional cable laying and burying method. 3 ... submarine cable, 4 ... laying device, 5 ... burying device, 6 ... trench machine, 7 ... sea bottom, 8 ... groove, 20 ... power ship, 21 ... cable laying simultaneous burying device , 22A, 22B ……
Float, 23 ... Stand, 24 ... Cable drum, 25 ...
Bell mouth, 26 ... Hole, 27 ... Cable outlet hole, 28 ...
Presser wheel, 32, 33 ... collar, 34 ... cable feeding hole, 35 ... pulley.

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Claims (2)

(57) [Claims] 1. A cable drum on which a submarine cable has been wound is mounted on a gantry, and the gantry is moved along the seabed, and at the same time, a groove is excavated by a grooving machine protruding from the gantry into the ground. In the method of simultaneously laying a submarine cable into which the submarine cable is dropped, the cable drum is arranged so that the axial direction of the cable drum is perpendicular to the horizontal plane of the gantry, and the submarine cable is wound with one twist per turn. A method of laying and burying a submarine cable, wherein the cable drum taken is mounted upside down on a gantry, the submarine cable is taken up, and the cable is fed into a groove excavated through the cable drum. 2. A gantry provided with a grooving machine which moves along the sea bottom and excavates a groove on the sea bottom, and is arranged so that the axial direction of the cable drum is perpendicular to the horizontal plane of the gantry. A cable drum in which a single twist is inserted to wind up the submarine cable is arranged upside down, and the submarine cable is taken up and fed through the cable drum into the groove excavated by the trench machine. And a cable drum mounted on the gantry.