JP2018028375A - Towing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply adjust buoyancy to an object to be laid in water.SOLUTION: A towing method for towing an object 1 to be laid, installed on a water bottom, in water by a ship S comprises: a coupling step of coupling, to the object 1 to be laid, a floating structure 2 including at least a floating body and a net-like bag body storing the floating body; a drawing step of connecting the object 1 to be laid to the ship S through a towline R, and drawing the object to be laid into water according to movement of the ship S; and a towing step of towing the object 1 to be laid, which is in a neutral floating state in water by coupling to the floating structure 2, to a place to be laid together with the floating structure 2 by the ship S.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a towing method for a laying object to be laid on a water floor, and more particularly to a towing method for towing a laying object to a laying place by a ship.

  2. Description of the Related Art Conventionally, when a laying object such as a pipe is laid on the bottom of the water, a laying method is known in which a pipe attached with a float and a weight chain is towed to a predetermined laying place (for example, Patent Document 1). reference.).

  In the towing method by the ship S of Patent Document 1, as shown in FIG. 4, the float (buoyant body) F is attached while the lower end of the chain C attached to the pipe P comes into contact with the water bottom B in a slack state. The pipe P is in a lifted state without contacting the bottom B. That is, the pipe P obtains a neutral buoyancy state in which it does not lift and sink in the water H, so-called neutral buoyancy, due to the buoyancy of the float F and the weight of the chain C in water.

JP-A-6-159553

  However, when the height from the bottom B to the pipe P varies in the water H, it is necessary to adjust the buoyancy with respect to the pipe P. At this time, if there is no float F having a size corresponding to the required buoyancy, it becomes necessary to newly produce a float having a size having the required buoyancy, which causes an increase in cost.

  Rather than changing the size of the float F, as shown in FIG. 5A, in order to increase the number of floats F attached to the pipe P to obtain the required buoyancy, the additional float F is attached to the pipe P. In addition, an additional attachment member E is required, and the number of steps for attaching the additional float F to the pipe P increases.

  Further, as shown in FIG. 5B, when a plurality of floats F are connected in series to form an aggregate U of the floats F, in addition to the step of connecting the aggregates U to the pipe P, the floats F The process of connecting the two in series is also necessary, and the operator is forced to perform complicated buoyancy adjustment work.

  Then, this invention is made | formed in view of said subject, and it aims at providing the towing method which can adjust easily the buoyancy with respect to the to-be-provided laying object.

  In order to achieve the above object, there is a towing method for towing a structure to be installed on the bottom of a water underwater by a ship, which comprises at least one buoyant body and a net-like bag body containing the buoyant body. A buoyancy structure in which the buoyancy structure is connected to the ship, and a buoyancy structure is connected to the ship. And a towing step of towing the laying structure in the state with a buoyancy structure together with the buoyancy structure to a laying place.

  In the towing step, it is preferable to adjust the neutral buoyancy by increasing or decreasing the number of the buoyancy bodies accommodated in the bag body based on the weight of the laying object.

  Further, in the connecting step, it is preferable that a predetermined weight is connected to the laying object in order to bring the laying object into a state of neutral buoyancy.

  Further, the buoyancy structure has a release device for releasing the connection state between the buoyancy structure and the laying object, and the buoyancy structure released by the release device in the towing step is on the water surface. Preferably it is recovered.

  Moreover, the said installation thing is a flexible elongate body, and it is preferable to connect the said buoyancy structure to several places over the longitudinal direction in the outer peripheral surface of the said elongate body in the said connection process.

  According to the present invention, it is possible to easily adjust the buoyancy with respect to the towing construction.

It is a figure which shows roughly the towing method which concerns on this Embodiment. It is a figure for demonstrating the structure of a towed structure. It is a figure for demonstrating separation of the buoyancy structure from a pipeline. It is a figure which shows the conventional towing method roughly. It is a figure for demonstrating the structure of the conventional float.

<Embodiment>
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are merely examples, and various forms can be taken within the scope of the present invention.

  FIG. 1 is a diagram schematically showing a towing method according to the present embodiment. FIG. 2 is a diagram for explaining the configuration of the towed structure. FIG. 3 is a view for explaining separation of the buoyancy structure from the pipeline.

<Configuration of towed structure>
As shown in FIG. 1, a towed structure 100 towed by a ship S includes a pipeline 1 as a laying structure, at least one (a plurality in FIG. 1) buoyancy structure 2, and a buoyancy structure 2. The number of chain bodies 3 corresponding to each of the above. The ship S navigates by pulling the towed structure 100 formed in the land L to a predetermined installation location of the underwater H set in advance (hereinafter also referred to as “towing”).

  The towed structure 100 is connected to the ship S via the towline R. The towed rope R has one end fixed to the ship S and the other end connected to the pipeline 1 of the towed structure 100, and is used for towing the towed structure 100 by the ship S. The towing rope R is only required to be excellent in wear resistance and impact resistance, and is formed of, for example, a steel rope or a rope made of synthetic fibers such as polyester, nylon, polypropylene, and polyethylene.

[pipeline]
The pipeline 1 is laid on the bottom B of a sea, a lake, a river, or the like, and is, for example, a long fluid transport pipe such as a seabed water supply pipe, a seabed oil supply pipe, or a seawater intake pipe. The pipeline 1 has flexibility and is made of, for example, high density polyethylene.

  In addition to the pipeline 1, for example, a long body such as a submarine cable for electric power and communication (including optical communication), a weight installed on a water bottom, etc. It may be a structure.

  As shown in FIG. 2, connecting members Cn are attached to the outer peripheral surface of the pipeline 1 at predetermined intervals over the longitudinal direction of the pipeline 1. The connecting member Cn is connected to the buoyancy structure 2 in a state where the connecting member Cn can be separated from the buoyancy structure 2 via a release device 23 described later.

[Buoyant structure]
As shown in FIG. 2, the buoyancy structure 2 includes a net-like bag body 21 and at least one or more buoyancy bodies 22 accommodated in the bag body 21.

  The bag body 21 is formed, for example, by knitting in a mesh shape with a synthetic fiber such as polyester, nylon, polypropylene, or polyethylene, or a wire using a metal material. The bag body 21 has an opening for taking in and out the buoyancy body 22. The opening is closed by a binding member 21a such as a metal or chemical fiber rope or wire. The bag body 21 has a mesh having a size such that the buoyancy body 22 accommodated in the bag body 21 does not jump out. For example, the bag body 21 can accommodate a plurality of buoyancy bodies 22 that give the pipeline 1 a buoyancy of about 78.45 kN (kilonewtons).

  The bag body 21 has been conventionally used to store a predetermined lump (crushed stone, concrete piece, etc.) and fix the pipeline 1 in the bottom B to the bottom B. In the present embodiment, It is used to accommodate the buoyancy body 22.

  At least one buoyancy body 22 is accommodated in the bag body 21 (in this case, a plurality of buoyancy bodies 22), and gives a predetermined buoyancy to the underwater H pipeline 1. The buoyancy body 22 is formed of, for example, a synthetic resin such as ABS resin, polyethylene resin, polypropylene resin, or expanded polystyrene resin, or other materials. In addition, all the buoyancy bodies 22 accommodated in the bag body 21 may have the same size, or may have different sizes.

  The buoyancy structure 2 has a known release device 23 that releases the connection state with the pipeline 1. The release device 23 is disposed between the bag body 21 and the connecting member Cn. The release device 23 is connected to the buoyancy structure 2 via a connection member 24 such as a metal or chemical fiber rope or wire, and is connected to the connecting member Cn via a hook (not shown), for example. It is connected with. The release device 23 is a functional unit that separates the buoyancy structure 2 from the pipeline 1 by releasing the connection state between the connection member Cn attached to the outer peripheral surface of the pipeline 1 and the buoyancy structure 2.

  For example, the release device 23 has a drive mechanism that receives a sound wave signal transmitted from the ship S or the land L in water and releases the connection state with the connection member Cn according to the sound wave signal. This drive mechanism has, for example, a plunger (not shown) having a gas generating agent as a driving force and a hook connected to the plunger. The hook is detachably connected to the connecting member Cn. The gas generating agent is ignited by the electric power generated by receiving the sound wave signal, and the plunger is operated by the gas pressure generated by the gas generating agent to open and close the hook. It is the structure to do. The release device 23 after being disconnected from the connection member Cn floats together with the buoyancy structure 2 and reaches the water surface.

[Chain body]
The chain-like body 3 is, for example, a weight that acts to sink the pipeline 1 to the bottom B. One end of the chain 3 is connected to the connecting member Cn, and the other end is grounded to the water bottom B. The chain body 3 is formed in a chain shape by connecting a plurality of ring members 31 to each other. The ring member 31 is detachably connected to another adjacent ring member 31. The weight is not limited to the chain body 3, and a weight in which a lump such as metal or concrete is integrally attached to the tip of a rope-like member connected to the connecting member Cn may be used.

<Pipeline towing method>
FIG. 1 shows a towing method for towing underwater by a ship S without causing the pipeline 1 to follow the bottom B but grounding it. The “tow method” includes a process from the step of forming the towed structure 100 in the land L to the step of separating the pipeline 1 in the underwater H and bottoming it.

  First, in order to adjust the neutral buoyancy of the pipeline 1, the required number of buoyancy bodies 22 are accommodated in the bag body 21 to form the buoyancy structure 2. Here, the number of the buoyancy bodies 22 accommodated in the bag body 21 is based on the weight of the pipeline 1 in the water H (hereinafter also referred to as “underwater weight”). It is set appropriately so as to be in a state.

  The neutral buoyancy with respect to the pipeline 1 can be easily adjusted by simply storing the necessary number of buoyancy bodies 22 in the bag body 21 (or removing them as necessary). The operation | work which connects the several float F required in H to the pipe P (refer FIG. 5A), and the operation | work which connects the floats F mutually and construct | assembles the aggregate | assembly U (refer FIG.5B). .) Can also be omitted.

  A connecting member Cn is attached to the outer peripheral surface of the pipeline 1 at predetermined intervals over the longitudinal direction, and the buoyancy structure 2 and the chain-like body 3 are connected to the pipeline 1 via the connecting member Cn (connecting step). The buoyancy structure 2 is connected to the pipeline 1 so that the attitude of the pipeline 1 during towing is substantially linear along the bottom B. Thus, the towed structure 100 is formed.

  After the towed structure 100 is formed, the tip of the pipeline 1 on the side of the ship S is connected to the ship S by the towline R. Thereafter, the ship S is moved in the direction of arrow A, and the towed structure 100 is drawn from the land L to the underwater H (retraction process).

  The pipeline 1 has an opening on the ship S side that opens to the outside. When the ship S is moved in the direction of arrow A and the pipeline 1 is pulled in from the land L side, seawater sequentially enters the pipeline 1. Filled. Thus, the pipeline 1 is towed to the laying location together with the buoyancy structure 2 while maintaining the neutral buoyancy (towing process). In the towing process, the buoyancy structure 2 is preferably in a state where it does not float on the water surface, that is, in the water H.

  When the pipeline 1 cannot maintain a stable neutral buoyancy state, the neutral buoyancy is adjusted in the water H. Specifically, the bundling member 21a is removed from the bag body 21 of the buoyancy structure 2 in the water H to open the mouth of the bag body 21, and the buoyancy body 22 is additionally accommodated in the bag body 21, or the buoyancy body 22 The neutral buoyancy can be easily adjusted by taking out the.

  Further, in the towing process, the neutral buoyancy of the pipeline 1 can be finely adjusted by attaching the ring member 31 to the chain body 3 or removing the ring member 31 from the chain body 3.

  After towing the pipeline 1 to the laying location, the buoyancy structure 2 is separated from the connecting member C as shown in FIG. Can be performed (separation process). Since individual sound wave signals can be set for the release device 23 of the buoyancy structure 2 connected to the pipeline 1, the timing for separating each buoyancy structure 2 from the pipeline 1 can be freely set. Can do. That is, the operation of separating the plurality of buoyancy structures 2 from the pipeline 1 can be performed simultaneously or sequentially with a time difference.

  Since the bag body 21 in a state where the buoyancy body 22 is accommodated floats up to the water surface, the operator can easily collect the buoyancy body 22. Regarding the bag body 21 of the recovered buoyancy structure 2, after the buoyancy body 22 is taken out, if the filling material such as stone or concrete is accommodated in the bag body 21, the top of the pipeline 1 installed on the bottom B Can be reused as a bag for the protective member of the pipeline 1.

  According to the towing method of the pipeline 1 as described above, the neutral buoyancy applied to the pipeline 1 is adjusted by appropriately selecting the required number and a predetermined size of the buoyancy body 22 to be accommodated in the bag body 21. Alternatively, the neutral buoyancy with respect to the pipeline 1 can be easily adjusted as compared with the conventional method.

1 Pipeline
2 Buoyancy structure 21 Bag body 22 Buoyancy body 23 Release device 3 Chain body (weight)
31 Ring member B Bottom Cn Connecting member H Underwater R Towing line S Ship

Claims (5)

A towing method for towing a structure to be installed on the bottom of a water underwater by a ship,
A connecting step of connecting a buoyancy structure comprising at least one buoyancy body and a net-like bag body containing the buoyancy body to the laying object;
A retraction step of connecting the laying object to the ship by a towline and drawing it into water according to the movement of the ship;
A towing step of towing the laying structure, which is neutral buoyant in water by the buoyancy structure, with a buoyancy structure together with the buoyancy structure to a laying place;
A towing method for a fabric structure, comprising:   2. The laying structure according to claim 1, wherein, in the towing step, the neutral buoyancy is adjusted by increasing or decreasing the number of the buoyancy bodies accommodated in the bag body based on a weight of the laying structure. Towing method.   3. The towing method according to claim 1, wherein, in the connecting step, a predetermined weight is connected to the laying object in order to place the laying object in a state of neutral buoyancy. The buoyancy structure has a release device for releasing the connection state between the buoyancy structure and the fabric structure,
4. The towing method according to claim 1, wherein, in the towing step, the buoyancy structure released by the release device is collected on a water surface. The fabric article is a flexible long body,
5. The towing method according to claim 1, wherein in the connecting step, the buoyancy structure is connected to a plurality of locations over a longitudinal direction on an outer peripheral surface of the long body. .

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