JP5418939B2 - Offshore floating structure mooring device by chain and installation method thereof - Google Patents

Description

  The present invention relates to an offshore floating structure moored using a chain for offshore floating structures equipped with precision machinery in a deep offshore area such as GPS wave measurement equipment, mooring facilities and coastal structure position indicators. The present invention relates to an apparatus and an installation method thereof.

  Japan has been affected by many tsunamis in the past, and while the occurrence of the Miyagi-ken-Oki earthquake and the Tokai / Nankai / Tonankai earthquake tsunami is imminent, tsunami countermeasures are urgently needed, and in recent years typhoons have landed in Japan However, typhoon countermeasure technology is being developed.

  As one of these countermeasure technologies, a mooring buoy-type wave measuring equipment using mooring chains and anchors is installed offshore far away from the land so that tsunamis and typhoons can be detected as soon as possible. Yes.

  The mooring chain input method includes a sending-out method, a crane ship method, and a free-fall method. The free-fall method has many results and is advantageous in terms of cost and construction, but because it is a method of dropping heavy anchors and mooring chains from below the surface of the water, the impact force at the time of landing is moored at deep water. There is a problem that the floating structure itself is spread through the chain and the safety of the precision machine mounted is impaired.

  In addition, after mooring, there is a problem that even when a high wave acts, an impact force acts on the floating structure, which impairs the safety of the mounted precision machine.

  On the other hand, it is verified that the part where the mooring chain mooring offshore floating bodies such as mooring buoys is concentrated at the connecting part between the mooring chain and the mooring buoy and the connecting part between the anchor and the mooring chain. A method has been developed in which a cushioning material is interposed in a portion to prevent a mooring chain cutting accident (for example, Non-Patent Document 1).

Further, as a cushioning material, a structure in which a plurality of chain rings constituting a chain are elastically expanded and contracted by being embedded in a rubber-like elastic material without being brought into contact with each other has been developed (for example, Patent Document 1 and 2).
"Port Technical Document No. 816 Dec. 1995" Port Technology Research Institute, Ministry of Transport JP-A-5-340447 Japanese Patent Laid-Open No. 1-150041

  However, the conventional mooring of offshore floating structures using cushioning materials is intended to prevent mooring chain breakage accidents, and offshore structures equipped with precision equipment such as mooring buoy wave measurement equipment. There is a problem that it is not possible to alleviate the impact on the precision equipment mounted on the PC and prevent damage to the equipment due to the impact.

  In addition, the conventional mooring chain is frequently struck against the bottom of the water by the ocean floating structure moving up and down by waves and moving in the horizontal direction, which significantly increases wear. At the same time, there was a problem that sand at the bottom of the sea entered between the chain rings that were connected, and the chain rings were scraped by rubbing the sand and the middle length part of the mooring chain was cut.

  In view of such conventional problems, the present invention is based on a mooring chain for precision equipment mounted on an offshore floating structure to be anchored in both cases of anchor and mooring chain being thrown and moored after being thrown. The purpose of this is to provide an offshore floating structure mooring device with a chain that can alleviate the impact and maintain the normal functions of precision instruments and prevent the middle part of the mooring chain from being cut. .

The feature of the invention according to claim 1 that solves the conventional problems as described above and achieves the intended purpose is that an offshore floating structure equipped with precision instruments is attached to an anchor on the bottom of the water via a mooring chain. In an offshore floating structure mooring device with a chain to be moored,
The mooring chain has a ground contact length part that is in contact with the water bottom surface by a predetermined length from the anchor when the sea surface is in a calm state, and a drooping length part that reaches the water bottom surface vertically from the offshore floating structure. And a buffer material interposed between both ends of the mooring chain, a position at a lower end portion of the hanging long portion that does not contact the water bottom regardless of the tides, and a hanging length of the ground contact length portion. The cushioning material is interposed in each of the positions on the side of the section that are not separated from the bottom of the water depending on the tides.

  The invention according to claim 2 is characterized in that, in addition to the configuration of claim 1, the cushioning material embeds a short chain composed of a plurality of chain rings in a rubber-like elastic material without contacting adjacent chain rings, The short chain has a structure having shackles at both ends.

  The feature of the invention described in claim 3 is that the anchoring chain is an offshore floating structure anchoring device using a chain that anchors an offshore floating structure mounted with precision instruments to an anchor on the bottom of the water via the anchoring chain. The mooring length is a length having a ground contact length portion that is in contact with the bottom surface of the water for a predetermined length from the anchor and a drooping length portion that reaches the bottom surface in the vertical direction from the offshore floating structure when the sea surface is calm. The buffer material is interposed at both ends of the chain, the position of the lower end portion of the hanging long portion that does not contact the water bottom regardless of the tides, and the position of the contacted long portion on the side of the hanging long portion A mooring device with a cushioning material interposed between the mooring chain and the position where it does not move away from the bottom of the water depending on the tides. From the offshore floating structure side of the structure, the bottom mooring chain is extended to the bottom of the water surface, and the remaining mooring chain is secured to the work ship at fixed length positions with the deepest part reaching 1/2 to 1/4 of the water depth. Then, after the anchor side end portion of the mooring chain is thrown into the water together with the anchor, the anchoring device for the offshore floating structure is installed by the chain so that the anchoring is sequentially released by the weight of the anchor side. Is in the way.

  In the offshore floating structure mooring device according to the present invention, as described above, the mooring chain includes a ground contact length portion that is in contact with the bottom surface of the water by a predetermined length from the anchor, and the offshore floating structure from the anchor surface when the sea surface is calm. It has a length that has a drooping length that reaches the bottom of the water in the vertical direction, and a cushioning material is interposed at both ends of the mooring chain, and is at the lower end position of the drooping long portion and is associated with the tides By interposing a cushioning material at a position that does not contact the bottom surface of the water and a position at the end of the contacted long portion side of the ground contact length portion that does not separate from the bottom surface depending on the tides, Whether the anchor or mooring chain is thrown or moored after being thrown, the impact from the mooring chain on the precision equipment mounted on the offshore floating structure to be moored is reduced, and the precision equipment It is possible to maintain the normal function, the cutting of the intermediate portion of the mooring chain is prevented.

  Further, in the method for installing the offshore floating structure mooring device according to the present invention, the mooring chain is in contact with the bottom of the water by a predetermined length from the anchor in the sea surface calm state regardless of the tides. A length having a ground contact length portion and a hanging length portion having a length that reaches the bottom of the water vertically from the offshore floating structure, and a buffer material interposed at both ends of the mooring chain, and a lower end of the hanging length portion A position that is not in contact with the bottom surface regardless of the tides and a position at the end of the ground contact portion on the drooping long side, and that is not separated from the bottom surface depending on the tides Using the offshore floating structure mooring device interposing cushioning materials, the offshore floating structure is floated on the surface of the water, and the mooring chain is sequentially fed from the offshore floating structure side below the surface of the water. 1 is deep in the water By securing the remaining mooring chain to the work ship at every fixed length position in a state where the depth of 2 to 1/4 is reached, and then throwing the anchor side end of the mooring chain into the water together with the anchor The anchors and the mooring chain are allowed to be released sequentially by the weight of the anchor side, and the anchor and the mooring chain are settled on the water bottom surface. The impact applied to the object is reduced, and damage to the mounted precision instruments can be prevented.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of an offshore floating structure mooring apparatus according to the present invention. In the figure, 1 is an offshore floating structure equipped with precision instruments such as a wave measuring instrument and a data transmitter, 2 is a mooring chain for mooring the structure 1 to the bottom of the water, and 3 is an anchor.

  In this mooring chain 2, an upper end cushioning material 5 a is connected to the connecting portion with the structure 1, and a lower end cushioning material 5 b is connected to the anchor 3, with a desired interval around the middle length of the mooring chain. A total of four buffer materials, that is, two intermediate upper buffer materials 5c and intermediate lower buffer materials 5d are connected.

  As shown in FIG. 2, each buffer material has a short chain 10 composed of a plurality of chain rings 10 a, 10 a... Embedded in a rubber-like elastic material 11 without contacting adjacent chain rings. A structure having shackles 12 at both ends can be used. The offshore floating structure 1, the mooring chain main body 2a, or the anchor 3 are connected to each other through the shackles 12, and the mooring chain 2 is constituted by the buffer materials 5a to 5d and the mooring chain main body 2a.

  The mooring chain 2 includes a ground contact length L2 that is in contact with the bottom of the water for a predetermined length from the anchor when the sea surface is in a calm state, and a drooping length that reaches the bottom of the water vertically from the offshore floating structure 1 L1 and the total length is about twice the water depth.

  The middle upper cushioning material 5c is located at the lower end position of the drooping long portion L1 and does not contact the water bottom surface 4 regardless of tides, more specifically, 1 m or more above the water bottom surface 4 at all times. It is linked to a certain position.

  Further, the intermediate lower cushioning material 5d is an end portion of the ground contact length L2 on the drooping long side, and is connected to a position that does not separate from the water bottom 4 depending on the tides when the sea surface is calm. .

  As shown in FIG. 3, the offshore floating structure mooring device configured as described above is configured such that impacts when the structure 1 moves up and down due to high waves and when the anchor 3 and the mooring chain 2 are initially charged are buffered at the upper end. The impact transmitted from the mooring chain 2 is reduced by the material 5a and the intermediate upper cushioning material 5c.

  In the case of high waves, as shown in FIG. 4, the structure 1 is flowed in the horizontal direction, and the shock in the state where the entire mooring chain 2 is separated from the water bottom surface 4 is alleviated by the shock absorbing materials 5 a to 5 d. .

  Further, when the ground contact length L2 drags the water bottom surface 4 as shown in FIG. 5 during rough waves, the shock is reduced by the buffer materials 5a, 5c, 5d, and the water bottom surface 4 is dragged at that time. Is reduced by the cushioning material 5d.

  Next, an example of a mooring method for an offshore floating structure according to the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the structure 1 is floated on the water, and the mooring chain is sequentially fed out by the crane 22 while the structure 1 is moved in a direction to be released from the work ship 21 on which the mooring chain 2 is mounted.

  When the deepest portion of the mooring chain 2 drawn out in this manner hangs down to the U-shape reaches about 1/2 to 1/4, preferably about 1/3 of the water depth, the feeding by the crane 22 is stopped. As shown in FIG. 7, the remaining mooring chain 2 is secured to the hull of the work ship at fixed lengths and suspended in a zigzag shape in the vertical direction. In addition, this lashing can withstand the weight of the mooring chain 2 in a normal state, but when a downward load of a predetermined value or more is applied, that is, after the anchor is inserted, which will be described later, the dynamic load of the anchor and the chain that sinks with the impact is impacted. Use a lashing tool that will unlock when you join. When the anchor 3 is thrown into the water in this state, the anchor 3 and the mooring chain 2 connected to the anchor 3 sink, and the first lock is generated by the downward impact load generated when the tip of the mooring chain 2 is fully extended. It will be solved.

  This action is repeated in sequence, the last lash is released as shown in FIG. 8, the mooring chain 2 is settled with its upper end supported by the structure 1, and the suspended length L1 is fully extended. Then the bottom of the bottom reaches the bottom. The shock at the time of bottoming is relieved by the buffer materials 5a and 5c. In addition, in order to reduce the impact at this time, the structure 1 is brought closer to the work ship 21 by the support ship 20. Next, the ground contact length L2 sequentially reaches the bottom, and the mooring operation is completed.

It is a side view which shows schematic structure of the offshore floating structure mooring apparatus which concerns on this invention. It is sectional drawing which shows an example of the shock absorbing material used for the offshore floating body structure mooring apparatus which concerns on this invention. It is a side view which shows the impact state concerning a mooring chain at the time of the sea surface calm of the offshore floating body structure mooring apparatus which concerns on this invention, and a mooring chain throwing in. It is a side view which shows the state in which the mooring chain whole was separated from the water bottom face 4 at the time of high waves same as the above. It is a side view which shows the state in which the grounding length part of a mooring chain same as the above is dragged. It is a side view which shows the initial delivery state of the mooring chain of an example of the installation method of the offshore floating structure mooring apparatus which concerns on this invention. It is a side view which shows the initial state after anchoring, after securing a mooring chain same as the above. It is a side view of the state where all the lashes same as the above were released.

L1 Suspended long part L2 Grounding length part 1 Offshore floating structure 2 Mooring chain 2a Mooring chain main body 3 Anchor 4 Water bottom 5a Upper end cushioning material 5b Lower end cushioning material 5c Middle upper cushioning material 5d Middle lower cushioning material 10 Short chain 10a Chain ring 11 Rubber elastic material 12 Shackle 20 Support ship 21 Work ship 22 Crane

Claims (3)

In an offshore floating structure mooring device with a chain that anchors an offshore floating structure equipped with precision equipment to an anchor on the bottom of the water via a mooring chain,
The mooring chain has a ground contact length part that is in contact with the water bottom surface by a predetermined length from the anchor when the sea surface is in a calm state, and a drooping length part that reaches the water bottom surface vertically from the offshore floating structure. Length,
While interposing a cushioning material at both ends of the mooring chain,
The position of the lower end of the drooping portion that does not contact the bottom of the water regardless of the tides, and the position of the side of the drooping long side of the ground contact length, depending on the tides An offshore floating structure mooring device using a chain, characterized in that a cushioning material is interposed in each of the positions where it does not leave.   The buffer material has a structure in which a short chain body composed of a plurality of chain rings is embedded in a rubber-like elastic material without contacting adjacent chain rings, and shackles are provided at both ends of the short chain body. Offshore floating structure mooring device using the chain described in 1.   In an offshore floating structure mooring device that anchors an offshore floating structure equipped with precision equipment to an anchor on the bottom of the water via a mooring chain, the mooring chain is only a predetermined length from the anchor when the sea surface is calm. A length having a ground contact length that is in contact with the water bottom surface and a hanging length portion that reaches the water bottom surface in a vertical direction from the offshore floating structure, and a buffer material is interposed between both ends of the mooring chain. A position at the lower end of the drooping long portion that does not contact the bottom of the water regardless of the tides, and a position at the end of the grounding long portion on the drooping long side, depending on the tides Using a mooring device with a cushioning material interposed at a position that is not separated from the bottom surface, the mooring chain is placed in order from the offshore floating structure side with the offshore floating structure floating on the water surface. The remaining mooring chain is secured to the work ship at every fixed length position with the deepest part reaching 1/2 to 1/4 of the water depth, and then the anchor of the mooring chain. A method of installing an offshore floating structure mooring device using a chain in which a side end portion is poured into water together with an anchor so that the anchoring is sequentially released by the weight of the anchor side.

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