JPH0775229A - Burying trough for submarine cable - Google Patents

Abstract

PURPOSE:To make cable-laying work easier by locating rollers when a cable passes and also by locating partial trough planes when repeaters pass above openings placed at proper intervals on the floor of a trough for a submarine cable. CONSTITUTION:A plastic material 2 having a small frictional force is adhered to the surface of a trough floor 3 made of steel or the like thereby forming a U-shaped trough bearing a submarine cable line 1 and a repeater 12. Openings 13 are made at proper intervals in the trough. When the cable 1 passes through the opening 13, a V-shaped arm 6 is rotated around a shaft 7, and a roller 5 rotatable around a roller shaft 4 enters the trough and supports the cable 1. Also when a repeater 12 passes through the opening 13, an L-shaped arm 9 is rotated around a shaft 10 and the repeater 12 is supported by a partial trough 9 consisting of a trough floor 3' and a plastic material 2'. By doing this, the frictional force is reduced and the trough for submarine cable-burying ship can be constructed at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trough arranged at the tail of a buried ship for laying a submarine cable on the seabed.

[0002]

2. Description of the Related Art When a submarine cable is buried in the seabed, the cable is wound around a rotary drum provided on the stern side for a plurality of turns to provide a drum cable engine having a large holding drive force, and a plurality of tires to be opposed. The submarine cable is unwound from a laying mechanism called a linear cable engine that holds and drives the cable by holding it at the stern through a trough with a U-shaped cross section, and is towed by a buried ship at the bottom of the sea. I try to bury it through.

FIG. 4 is a schematic view showing the appearance of the submarine cable fed from the buried ship, showing the rear part of the buried ship 20. At the stern of the buried ship 20, there is provided a chute 21 formed in a bell mouth shape for lowering the undersea cable 30 into the sea, and the undersea cable supplied to this chute 21 is a trough 22 formed in a U shape. Has been introduced by the guide.

Reference numerals 23 and 23 denote linear cable engines for sending a submarine cable pulled out from a turn-bottomed tank 24 by a pulling mechanism to a chute 21 through a trough 22, which is enlarged and shown in FIG. A plurality of rotating tires 23a, 23a.
The submarine cable 30 is carried to the trough 22 side at a predetermined speed while sandwiching the submarine cable 30 by.

By the way, the trough 2 arranged at the stern
Not only the submarine cable but also a repeater for amplifying the signal transmitted by the submarine cable and a joint box (JB) 12 for electrically and mechanically connecting the cable and the cable pass through the submarine 2.

The most advanced burial method is tow wire for towing the burial machine from the stern of the burial vessel 20, umbilical cable for sending electric power to the burial machine, and transmission / reception of control signals and submarine cable. It is delivered from the stern.

FIG. 6 shows the relationship between the cable ship 20 and the burial machine 40 before the burial operation is started. (A) is a state when the burial machine 40 is being lowered, and (b) is a burial machine. During preparation period for towing 40, (c) is under buried towing.

In FIG. 6 (a), first, the burying machine 40 loaded on the ship is lowered from the stern crane 25 into seawater, and the cable ship 20 is slowly advanced while the tow wire 31 and the cable 30 are adjusted in accordance with the forward speed. And the umbilical cable 32 is paid out. The retention of the tow wire 31 for advancing the burying machine 40 is attached to the tip of a frame called a draw bar, which is fixed by a pivot type whose angle is changed by hydraulic pressure.

The tow wire 31 and the submarine cable 30 are very close to each other and are fed from the stern, and are also very close to each other on the burying machine 40 side.
It is not empirical that the two are entwined at a constant speed and are entangled with each other. The anvil cable 32 for transmitting the signal of the television camera provided in the burying machine 40 and for transmitting the control signal to the burying machine 40 has a float attached and is extended for a long time, so that it does not get entangled with this.

In FIG. 6B, for example, after landing on the seabed at a water depth of about 1000 m, only the cable burying ship 20 advances with the burying machine 40 stopped, and the tow wire 3 correspondingly moves.
1, the submarine cable 30 and the umbilical cable 32 are paid out. The distance between the embedding machine 40 and the cable ship 20 is being increased in order to obtain a sufficient horizontal component force for towing the embedding machine 40. The drawbar on the side of the embedding machine 40 gradually falls forward due to hydraulic pressure. Controlled by.

The process of this preparatory stage is a very important process because it is necessary to pay out so that the tow wire 31 and the submarine cable 30 do not cross each other. The submarine cable 30 must always be below the tow wire 31. That is, for the submarine cable 30, it is necessary that the cable fed from the laying mechanism on the ship be fed from the stern for a required length.
When the frictional force on the trough 22 and the chute 21 on the above-mentioned buried ship is large, the payout speed of the submarine cable is slowed, and as a result, the submarine cable length in seawater is reduced, and the submarine cable 30 is positioned above the tow wire 31. There is a possibility of going to, causing entanglement. Since the onboard tension of the cable detected by the laying mechanism on the ship does not include the trough friction force T _T or the chute friction force T _S as shown in FIG. 4, it is fed from the buried ship 20. The tensile force T _{O of the} cable is higher than the detection value T of the laying mechanism.
Since the cable is controlled so as to be paid out in response to the detected value T, particularly when the frictional force of the submarine cable passing through the trough 22 changes, the payout length of the cable also changes, so that the frictional force at the trough or chute is reduced. It is necessary to reduce it as much as possible.

FIG. 6 (c) shows a state in which a submarine cable is attached to the tow wire 31 while a V-shaped groove is formed in the sea bottom by towing the burying machine 40, and a large tension is applied to the tow wire 31 to form a substantially straight line. Has become. When a tension higher than a frictional force is applied to the submarine cable 30 due to the underwater weight of the submarine cable 30, the submarine cable 30 is paid out from the ship via a trough. Therefore, the greater the frictional force on the ship, the submarine cable 3
0 becomes a straight line and is close to the tow wire 31. It is ideal that the submarine cable 30 slightly touches the seabed before the burying machine 40, and in such a case, there are few elements in which the tow wire 31 and the submarine cable 30 are entangled with each other.

However, when the seabed is shallow and the soil quality is soft, the tow wire 31 and the submarine cable 30 come close to each other in the seawater, and when the buried ship 20 passes through the stern's frictional force, especially the trough. If the frictional force is high, the submarine cable 30 may come over the tow wire 31 and become entangled. Therefore, the onboard tension needs to be as close as possible to the underwater weight of the cable.

As described above, among (a) to (c), the tow wire 31 and the cable 30 are most likely to be entangled with each other in the process of forming the towing posture of (b). Neglecting the influence of tidal currents and water flow resistance, the underwater catenary curves of the submarine cable 30 and tow wire 31 have the following unit lengths: underwater weight, ship tension,
Determined by the tension in the burial machine. The onboard tension of the submarine cable is such that the underwater weight of the cable is superimposed with the frictional force of the stern chute and trough, but since the underwater weight is smaller than that of the tow wire, the onboard tension becomes relatively large when these frictional forces are large. The distance between the tow wire and the catenary curve of the submarine cable is close to each other, which causes entanglement.

[0015]

Therefore, in order to reduce the frictional force at the stern, it is effective to provide a rotating sheep with a diameter of 3 m or more instead of the stern chute, but it is effective depending on the current of the sea and other operating conditions. Since the cable is not always paid out in the direction directly behind the buried ship 20, it is necessary to provide vertical rollers on both sides of the sheep, and the installation of these rotary sheep and rollers requires large equipment and is expensive. Will be things.

Further, since the frictional force at the stern is not limited to the stern chute, it is necessary to solve the problem of reducing the frictional force of the trough behind the laying mechanism such as the linear cable engine. When the relay is installed, vibration will occur when a repeater or joint box of a cable having an irregular shape passes, which may cause a failure of the repeater, and the entire bottom surface of the trough with a total length of several tens of meters is composed of rollers. Doing so will increase the cost. Further, a gap is inevitably formed between the rollers, and vibration and impact when passing through the repeater or joint box cannot be avoided.

Furthermore, the cable tension measured by the laying mechanism as described above does not substantially become the onboard tension of the cable, but changes due to the frictional force when passing through the trough. It is ideal that the submarine cable is paid out to the seabed under the weight of the underwater, but the distance between the tow wire and the catenary curve of the submarine cable fluctuates due to the influence of the frictional force of this trough. Was difficult to set.

[0018]

SUMMARY OF THE INVENTION The present invention has been made to solve such a situation, and when a buried cable fed from a ship is passed through a trough, it is intermittently opened on the floor of the trough, for example. An opening having a width of about 10 cm is provided, and a plurality of rollers mounted on the bottom surface of the trough are configured to rise in the trough in the opening. Then, the submarine cable passing through the trough can pass through the trough with a small rolling frictional force.

On the other hand, when the repeater or joint box passes through the trough, the roller is rotated to the back surface of the trough, and the partial trough to which the plastic having a small frictional force is attached is rotated from the back surface of the trough to open the trough. The trough surface is made of a plastic material that is flat and has a low frictional force, so that the frictional force does not change significantly when the submarine cable passes, even when passing through a repeater or joint box.

[0020]

[Function] The submarine cable dropped from the stern of the buried ship into the seawater is almost the same in the trough transferred to the chute of the stern in the line part of the submarine cable and the repeater part connecting the submarine cable. It becomes possible to move due to the low coefficient of friction, and the tensile force of the cable detected by the laying mechanism on the ship and the tensile force of the cable actually generated in seawater become substantially the same. As a result, the feeding speed of the cable can be accurately controlled.
INDUSTRIAL APPLICABILITY The present invention can solve the problem of the entanglement between the tow wire and the cable, which is likely to occur particularly in the initial stage of laying.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The essential parts of an embodiment of the present invention will be described in detail below with reference to FIG. 1 and enlarged view 2. As described above, the submarine cable is fed from the linear cable engine and is supplied into the trough, and the submarine cable passing through the trough is shown in FIG. 1. The partial trough 9 in FIG. An enlarged view of the cable support member 6 is shown in FIGS.

That is, FIG. 1 is a schematic view of the trough taken from the center in the longitudinal direction and seen from the side, and FIG. 2 (a) is a view of the opening of the trough when the line portion of the submarine cable passes through. Shows that the roller is moving and fixed,
FIG. 2B shows a state in which the partial trough is moved and fixed to the open portion of the trough when a submarine cable repeater, a joint box, or the like passes through.

In these figures, 1 is a line portion of a submarine cable passing through the trough, 2 is a plastic material having a small frictional force attached to the floor surface of the trough, and 2'is a partial trough 9 described later. A plastic material having a small frictional force attached to the flat surface portion 3 ', 3 is a trough floor made of iron or the like, 3'is a floor of a partial trough portion (9) also made of iron or the like (upper (Planar portion), 4 is a roller shaft, 5 is a roller having a V-shaped groove or a flat shape that rotates in contact with a submarine cable, and 6 is a V-shaped arm that supports the roller and forms a cable supporting member. It is a thing.

Reference numeral 7 is a shaft for rotating the V-shaped arm 6, 8 is a bearing portion for supporting the shaft 7 of the V-shaped arm fixed to both outer lateral surfaces of the trough, and 9 is an L-shaped member. A partial trough composed of an arm, 10 is a shaft for rotating the partial trough 9, and 11 is a bearing portion provided on both outer lateral surfaces of the trough and supporting the shaft 10 of the partial trough 9. .
1 and 2 (a) and 2 (b), the same parts are designated by the same reference numerals.

The repeater or joint box connecting the lines of the submarine cable is indicated by 12. The cable support member moves in FIG. 2 (a) and the partial trough 9 moves in FIG. 2 (b). Then, a case is shown in which the abutment is made against the openings 13 formed at a predetermined interval on the floor surface of the trough.

Next, the operation of the trough of this embodiment will be described. As shown in FIG. 1, the place sp1 where the line portion 1 of the submarine cable that is put into the water from the buried ship passes through the floor surface 2 of the trough 22 is fixed to both outer lateral surfaces of the trough. The V-shaped arm 6 fixed to the shaft 7 supported by the bearing is pivoted, and the other end is projected from the opening 13 of the trough and is provided at the other end of the V-shaped arm. The roller 5 fixed to the roller shaft 4 is controlled to be located on the floor surface of the trough. Then, the roller 5 abutting against the line portion 1 of the submarine cable passing through this trough rotates to convey the submarine cable in the arrow direction.
In this state, the partial trough 9 hangs on the shaft 10 below the back surface of the trough and is fixed downward.

Further, as shown in FIG. 1, in the trough through which the repeater or joint box 12 passes, or in the trough area SP2 which passes from now, the cable support of the V-shaped arm is supported in the opening 13 of the trough. A partial trough 9 is fitted instead of the member 6 to show that a repeater or joint box 12 having a large diameter is passing through. Unlike the rollers, the trough floor surface 3 does not have a height difference, so that it has less impact when passing and the relay can also pass through the trough smoothly with a small friction force.

As shown in FIGS. 3 (a) and 3 (b), V
The cable support member 6 and the partial trough 9 formed of a V-shaped arm are connected to the ends of the shaft 7 and the shaft 10 on opposite sides of both outer lateral surfaces of the trough 22, respectively.
A and 15B are provided, and locking portions 15C and 15C for locking the raising and lowering levers 15A and 15B are provided on the side surface of the trough 22.

Therefore, in order to change from FIG. 2 (a) to FIG. 2 (b), as shown in the embodiment shown in FIG. 3 (b), the raising / lowering lever 15B fixed at right angles to the shaft 7 on the back surface of the trough. The engaging portion 15C is released from the engagement, and the shaft 7 supporting the V-shaped arm 6 is rotated in the B direction to move to the rear surface of the trough. At this time, the opening 13 is once formed in the trough, but this time, the force is applied to the raising / lowering lever 15A fixed at a right angle to the shaft 10 on the outer side surface of the trough on the opposite side to the opening 13 of the trough. The flat portion of the partial trough 9 is rotated to close it. Partial trough 9 is trough opening 1
It is manufactured so that it fits exactly into the No. 3, and the trough has no irregularities and allows the repeater and the joint box 12 to pass through smoothly.

2B to 2A can be easily operated in a similar manner in a direction in which the partial trough 9 is separated from the trough opening portion 13 to move from the flat trough to the conveying state by the roller 5 in a short time. Can be changed to Further, even when the submarine cable is passing over the trough, this change allows the submarine cable line 1 and the joint box 12 to be connected.
It is possible for the operator to operate safely without damaging the cable to either of them.

The movement of the partial trough 9 and the cable supporting member 6 as described above may be performed by one operation by connecting the raising and lowering levers 15A and 15B by a crank mechanism. Further, this switching can be performed automatically by driving a motor or the like by obtaining the time when the repeater or the joint box 12 enters the trough by a sensor or a feeding distance. If the material forming the trough is plastic or the like, the plastic materials 2 and 2'which maintain smoothness may be omitted.

[0032]

As described above, according to the present invention, a plurality of rollers are intermittently installed on a trough through which a submarine cable separated from an embedded ship passes when a cable to be buried under the sea is introduced from the stern. Just before the repeater or joint box passes, the roller is changed to a flat trough with a simple operation, so when the line part of the submarine cable passes, it passes through the trough with a very small frictional force due to rolling friction, When passing the repeater or joint box, it is possible to pass the trough smoothly without giving an impact by passing it continuously over a flat plastic material having a small frictional force. Therefore, there is an effect that the catenary curve between the tow wire for submersible machine towing and the submarine cable is always separated by a certain distance, and the trough for embedding can be provided without the entanglement between the tow wire and the submarine cable.

Further, although the trough for burying a submarine cable of the present invention has a simple structure, it has been actually confirmed that the effect of reducing the frictional force is great, and an ideal burying trough is provided at a low cost. It has great practical value because it can be done.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an outline of a trough for burying a submarine cable of the present invention.

FIG. 2 is a view showing movement of a cable trough and a partial trough that moves to an opening of the trough.

FIG. 3 is an explanatory view showing a drive mechanism for a partial trough and a cable support member.

FIG. 4 is a diagram for explaining a stern portion of a submarine cable buried ship.

FIG. 5 is a diagram showing an outline of a linear cable engine that feeds a submarine cable to a trough.

FIG. 6 is an explanatory view of burying a submarine cable unloaded from a burial vessel on the seabed by a burial machine.

[Explanation of symbols]

 1 Submarine cable track 2, 2'Plastic material 3, 3'Trough floor 6 V-shaped arm cable support member 9 Partial trough 12 Repeater 20 Buried ship 22 Trough

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuro Yamaguchi 2-23 Nakameguro, Meguro-ku, Tokyo International Cable Ship Co., Ltd.

Claims (4)

[Claims] 1. In a cable burial vessel for burying a submarine cable in the seabed, the submarine cable is equipped with a tension between the cable engine and the chute, and the floor surface is provided with a plurality of openings at appropriate intervals. A U-shaped trough, a cable support member in which a roller is provided at the tip of an arm arranged so as to project from the lower side of the opening, and a portion having a flat surface portion for closing the opening. A trough, and when the line portion of the cable is passing through the trough, the cable supporting member projects into the opening and advances in the trough by the roller provided at the tip thereof. While supporting the cable and immediately before the joint box or repeater of the cable passes through the trough, the partial trough collides with the opening. ,
A trough for burying a submarine cable, wherein the floor surface of the trough is configured to be flat. 2. The trough for burying a submarine cable according to claim 1, wherein a plastic material having a small frictional force is placed on a floor surface of the trough and an upper flat surface portion of the partial trough. 3. The buried submarine cable according to claim 1, wherein the cable support member and the partial trough are rotatably supported by an axis orthogonal to a longitudinal direction of the trough. Trough. 4. The movement of the cable supporting member and the partial trough is adapted to be manually or automatically driven by a lever which rotates a rotation shaft thereof. The trough for submarine cable burial according to 3.