JP2012131332A - Mooring system of small vessel corresponding to tsunami - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mooring system without breaking a mooring rope, allowing a hull to drift or damaging the other object when attacked by a tsunami.SOLUTION: A space between the hull 1 and a mooring wharf is connected with a cushioning rope 3 interposed by a cushioning material 32, and a space between the hull 1 and a marker buoy 4 is connected with a mooring rope 5, a space between the marker buoy 4 and a seabed chain 9 is connected with a cushioning rope 6 interposed by a cushioning material 62, and the other end of the seabed chain 9 is connected to a seabed block 7. Furthermore, a plurality of groups of the mooring systems of the small vessels are provided so as to share the seabed block 7 present between the adjoining systems.

Description

  The present invention relates to a mooring system for small vessels (hereinafter referred to as “ships”) in consideration of safety during a tsunami attack.

There are about 1 million fishing boats, recreational fishing boats and pleasure boats in Japan, more than 90% of which are said to be small vessels with less than 5 gross tons.
As a mooring method for these ships, a vertical mounting method is generally used in which the bow portion is oriented at right angles to the mooring shore and only the bow portion is connected to the mooring pillar on the mooring shore with a rope.
Alternatively, as shown in FIG. 8, when the mooring berth has a margin and is unloaded, it is generally moored in a manner corresponding to a plurality of mooring pillars d of the pier a on the mooring shore and a plurality of locations on the berth side of the hull b. A side-mounting method has been adopted in which the cords are held together by a cable c.
In any of the mooring methods, it is known that when a large tsunami accompanied by a sudden rise and fall of the sea level strikes, a large shocking force is applied to the mooring line and the mooring line breaks.
As a result, a large number of ships start drifting with Tsunami at once in the harbor (hereinafter referred to as the harbor), such as a pool and anchorage.
When this is the rising tide, the ships will go up to the land while colliding with each other with waves, hitting residential areas and public facilities.
Also, at the time of tide, it was thrown into the open ocean along with the tide while being launched on the strands or waterways, causing a great deal of damage.

The problem with the conventional ship mooring system as described above is that the force to separate the mooring column from the bow or the berth side acts as an impact force on the mooring line due to the sudden rise or fall of the sea level in the port, and the mooring line is cut Or the bit that was the mooring bracket of the ship broke, and the drifting was to start with the rapid tide that followed.
However, although research on tsunami phenomena and research on external forces acting on ships have been conducted in the past, development of mooring systems based on reality has been delayed, and it is not possible to find them even by investigating patent literature .

In order to solve the above-described problems, a mooring system for a small vessel according to the present invention is provided with a buffering material between the hull and the mooring shore, and between the hull and the block on the seabed, in order to prevent tsunami. It is characterized by being connected with a rope.
Furthermore, the mooring system for a small vessel according to the present invention connects the hull and the mooring shore with a buffering rope with a cushioning material interposed therebetween, and connects the hull and the marker buoy with a mooring cable to prevent tsunami. The marker buoy and the submarine block are connected by a buffer cable with a buffer material interposed therebetween.
Furthermore, the mooring system for a small vessel according to the present invention connects the hull and the mooring shore with a buffering rope with a cushioning material interposed therebetween, and connects the hull and the marker buoy with a mooring cable to prevent tsunami. The marker buoy and the chain on the sea floor are connected by a buffer cable with a buffer material interposed therebetween, and the other end of the chain is connected to a block.
Further, a mooring system for a small vessel according to the present invention is characterized in that a plurality of sets of mooring systems for the above-mentioned small vessels are installed, and a submarine block existing between adjacent systems is shared.

Since the mooring system for a small vessel of the present invention is as described above, the following effects can be obtained.
<1> The sea surface changes rapidly due to the first tsunami attack, and the impact force acts on the mooring line, but the elastic buffering line relaxes the impact tension and absorbs drift energy to prevent the mooring line from breaking. To do. Although the second and third waves of the tsunami come close, the drift of the ship can be prevented in the same way.
<2> By installing blocks and chains, it is possible to resist the rapid flow that follows.
<3> By installing a marker buoy, it is possible to easily attach and detach mooring lines for tsunami countermeasures when leaving the ship or boarding the ship.
<4> Sometimes tsunamis are higher than expected and repeatedly hit several waves after a certain period of time. Even if a ship spills unfortunately in the first and second waves, damage can be reduced by attaching a spare buffer cable and reattaching to a different marker.
<5> With this system, it is possible to prevent the loss of a large number of ships due to tsunamis, and to reduce the risk of housing and public facilities behind the port being potentially destroyed by drifting objects.

Explanatory drawing of the Example of the mooring system of the ship of this invention. Explanatory drawing of the other Example of a mooring system. Explanatory drawing from the mooring shore side in normal times. Explanatory drawing from the mooring shore side at the time of the tsunami attack. Explanatory drawing from the side at the time of ship drifting. Explanatory drawing of the state which installed the some system in parallel. Explanatory drawing of the other Example of the combination of a some system. Explanatory drawing of the Example of the conventional mooring system.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

<1> Overall configuration.
The present invention targets ships of less than 5 gross tons, and combines the technologies of mooring lines 3, 5, buffer materials 32, 62, marker buoy 4, sea side block 7, etc. to scientifically determine the impact force and flow pressure of tsunami. This is the first mooring system to overcome.
Conventionally, there is a technology such as a system for preventing a ship from shaking, but there is no technology for suppressing the damage of a small ship during a tsunami.

<2> Sea side block.
The sea side block 7 is a weight installed on the sea floor so that the hull 1 is not washed away.
Specifically, it consists of a concrete block or a bag filled with stones.
In this system, the first impact force is absorbed by the buffer material of the bow side buffering cable 3 and the stern side buffering cable 6 at the time of the invasion of Tsunami, so the sea side block 7 does not function.
Thereafter, when a flow pressure is applied to the hull 1, it is the sea-side block 7 that generates a resistance against it.
The sea side block 7 resists by the weight of itself and also the frictional force with the sea bottom.
The sea side block 7 has a pulling force depending on the soil quality of the seabed, that is, the holding force is different for sand and rock, so it is desirable to conduct a tow experiment on site before installation and consider the material, weight, etc. .

<3> Chain.
A chain 9 connects between the sea side block 7 and the stern side buffer cable 6 described later.
That is, the other end of the stern side buffer cable 6 having one end connected to the marker buoy 4 is connected to the chain 9.
The other end of the chain 9 is connected to the sea block 7 described above.
At that time, as shown in FIG. 1, the stern side buffering cable 6, the chain 9 and the sea side block 7 are connected in a straight line, or as shown in FIG. It is also possible to adopt a configuration in which the both ends of the chain 9 are connected to the seaside block 7 in the middle of the chain 9.

<4> Connection of adjacent blocks.
Although the sea side block 7 can also be arrange | positioned independently on the seabed, between the adjacent sea side blocks 7 can also be connected with the interblock buffer cable 8 and the chain 9. FIG.
The inter-block buffer cable 8 is also configured by interposing a buffer material in the middle of the mooring cable, and connects the stern-side buffer cable 6 and the inter-block buffer cable 8.
Then, when the stern side buffering cable 6 extends more than a certain distance, a tensile force acts on the interblock buffering cable 8 to extend.
Further, the stern side buffer cable 6 is connected to the middle of the chain 9 connecting the sea side blocks 7.
Then, when the stern side buffer cable 6 and the inter-block buffer cable 8 extend beyond a certain level, the chain 9 is pulled and acts as a resistance.
Further, when the chain 9 is pulled to its limit, it becomes a force that moves the sea-side block 7 along the seabed and becomes resistance.
In some cases, it is possible to configure the size such that the chain 9 is pulled after the sea-side block 7 has moved first and lifted.

<5> Mooring line.
The hull 1 and the marker buoy 4 are connected by a stern mooring line 5.
The stern side mooring line 5 is made of a general material such as a commercially available fiber rope or steel rope.
A crew member of a ship can easily take measures against tsunamis only by a conventional operation of simply locking the end of the stern mooring cable 5 to the marker buoy 4 when leaving the ship.
When leaving the port, the mooring pole 3.6 and the mooring rope 3.6 anchored to the marker buoy 4 on the berth are removed.

<6> Buffer cable.
In the system of the present invention, a bow side buffer cable 3 that connects the bow side and the mooring column 2 and a stern side buffer cable 6 that connects the stern side and the sea side block 7 are used.
Each of the buffer cables 3 and 6 is configured by interposing buffer materials 31 and 61 in the middle of the mooring cable or at one end thereof.
The cushioning material to be interposed is a cord or belt-like member having high stretch characteristics, and relaxes impact tension and absorbs energy by high stretch characteristics.
The performance is determined based on the assumed tsunami conditions, and the energy absorption performance when the ship drifts due to the tsunami and the maximum tension that acts on the mooring rope during the drift are examined, and it is possible to cope with any condition. A function having performance.

A 漂流エネルギー
ここに、 Ｅ₀ ： 漂流エネルギー （ｔ・ｍ）
ｍ ： 船舶重量 （ｔ）
ｍ^' ： 仮想重量 （ｔ）
ｇ ： 重力加速度 （ｍ／ｓ²）
Ｖ₀ ： 漂流速度 （ｍ／ｓ）
ρ ： 海水の単位体積重量 （ｔ／ｍ³）
Ｄ ： 喫水 （ｍ）
Ｂ ： 船幅 （ｍ）
Ｂ 緩衝材に作用する最大張力

ここに、 T_max ： 緩衝材に作用する最大張力 （ｋｇｆ）
E ： 緩衝材のヤング率 （ｋｇｆ／ｃｍ²）
a ： 緩衝材の断面積 （ｃｍ²）
l₀ ： 索長さ （ｃｍ）
鴫原良典・藤間功司・大久保暢之・中村雅博・坪田幸雄・三宅健一・斎藤正文「津波船舶係留索に働く張力について」2008.11 地域安全学会論文集No10
pp387-392 引用
以上の（１）〜（３）式によって算出されるエネルギーや張力に対応可能な緩衝材を採用するが、津波の大きなエネルギーを吸収して係留索に作用する衝撃張力を緩和するためには伸びの非常に大きい緩衝材が必要となる。
津波の衝撃を受ける緩衝材は４〜５倍伸びることが想定される。
大津波は繰り返し５〜６波襲来するので、緩衝材を構成する材料はゴム弾性体やスプリングなどの繰り返し大きく伸縮できる特性を備えた材料を用いることが望ましい。 <7> Elongation of cushioning material.
The tsunami drift energy and the tension acting on the buffer are calculated by the following formula.

A Drifting energy
Where E ₀ : Drifting energy (t · m)
m: Ship weight (t)
m ^′ : virtual weight (t)
g: Gravity acceleration (m / s ² )
V ₀ : Drifting speed (m / s)
ρ: Unit volume weight of seawater (t / m ³ )
D: draft (m)
B: Ship width (m)
B Maximum tension acting on cushioning material

Where, T _max : Maximum tension acting on the cushioning material (kgf)
E: Young's modulus of cushioning material (kgf / cm ² )
a: Cross-sectional area of cushioning material (cm ² )
l ₀ : Cable length (cm)
Yoshinori Sugawara, Koji Fujima, Yasuyuki Okubo, Masahiro Nakamura, Yukio Tsubota, Kenichi Miyake, Masafumi Saito “Tensions Working on Tsunami Ship Mooring Lines” 2008.11 Proc.
pp387-392 Citation A buffer material that can handle the energy and tension calculated by the above formulas (1) to (3) is adopted, but it absorbs the large energy of the tsunami and reduces the impact tension acting on the mooring line. For this purpose, a buffer material having a very large elongation is required.
It is assumed that the shock absorbing material that receives the impact of the tsunami extends 4 to 5 times.
Since a large tsunami repeatedly attacks 5 to 6 waves, it is desirable to use a material having a characteristic capable of repeatedly expanding and contracting repeatedly, such as a rubber elastic body or a spring, as a material constituting the buffer material.

<8> Marker buoy.
A marker buoy is a buoy installed on the water surface.
With this marker buoy, it is possible to easily attach and detach the buffer cable including the sea side block and the mooring cable in the sea from the stern.
As for the marker buoy, a buoy with improved visibility at night such as fluorescence, phosphorescence or a self-light emitting device is desired considering emergency detachment such as at night.

<9> Multiple combinations.
In the present invention, a plurality of the mooring systems described above are arranged, and the seaside block 7 and the inter-block buffer cable 8 can be shared by connecting them at the seabed.
At that time, as shown in FIG. 6, the ends of the stern side buffer cables 6 are directly connected to the sea side block 7, and the adjacent sea side blocks 7 are connected to each other by an inter block buffer cable 8. Combinations can be employed.
Alternatively, as shown in FIG. 7, the combination of connecting the ends of the stern side buffer cables 6 to the interblock buffer cables 8 and connecting the adjacent sea side blocks 7 with the interblock buffer cables 8 and the chains 9. It can also be adopted.
As a result of adopting a plurality of combinations in this way, it is possible to disperse the external force with the ship adjacent to the net shape, and to ensure the safety of the ship in the entire port.

<10> Explanation of ship behavior.
Next, the ship behavior by the system of the present invention at the time of the tsunami attack will be described.

<11> Normal.
At normal times, the hull 1 is connected to the mooring column 2 and the marker buoy 4 by the buffer ropes 3 and 6 for tsunami countermeasures together with the normal mooring rope.

<12> Arrival of the first tsunami wave There are two cases of the first tsunami wave, when the sea level rises rapidly and when the tide is drawn until the seabed is visible.
In the former case, the hull 1 is lifted by waves, but the buffer line 32 of the bow side buffer line 3 having a length of several tens of centimeters to about 1 m that connects the mooring column 2 and the hull 1 is extended by several meters. Therefore, the tension acting on the mooring line 31 can be reduced, and the breakage of the mooring line 31 and the subsequent drifting of the hull 1 can be stopped.
In the case of a pulling wave, the hull 1 leaves the shore so that it can be swept offshore, and the seabed of the port can be seen, but the bow side buffer rope 3 is not cut off by the same function as the above-mentioned sea level rise. The hull 1 is thus sitting in a state of being connected to the mooring column 2.
If the cushioning material 32 is not present, the mooring rope will break because the shocking tension due to the tsunami acts on the mooring rope.

<13> A state of a large tsunami and a fast tide.
When the sea level rises further and the flow continues rapidly due to the tsunami, the extension of the buffer cable 62 of the stern side buffer cable 6 reaches the limit.
However, in the next stage, the chain 9 on the seabed is pulled and becomes a load, and further, the sea side block 7 as an anchor moves while resisting by its holding force, thereby suppressing the drift of the hull 1.
The gripping force here refers to the force that resists when a seabed ridge or block is pulled on the seabed.

<14> Second wave, third wave, repeated attack and hull position correction.
The rise of the sea level of the first wave is over, it returns to the normal water level, each member that has been stretched in the time until the second wave strikes contracts back to its original length, and the hull 1 is in a stable posture The position can be restored.

1: Hull 2: Mooring column 3: Bow side buffer cable 4: Marker buoy 5: Stern side mooring cable 6: Stern side buffer cable 7: Sea side block 8: Interblock buffer cable 9: Chain

Claims (4)

For measures against tsunami,
Between the hull and the mooring shore, and between the hull and the block on the sea floor,
Constructed by connecting with a buffer cable interposing a buffer material,
Mooring system for small vessels. For measures against tsunami,
The hull and the mooring berth are connected by a buffer cable with a buffer material interposed between them,
Connect the hull and the marker buoy with a mooring line,
Between the marker buoy and the block on the sea floor, connected with a buffer cable interposing a buffer material,
Mooring system for small vessels. For measures against tsunami,
The hull and the mooring berth are connected by a buffer cable with a buffer material interposed between them,
Connect the hull and the marker buoy with a mooring line,
The marker buoy and the chain on the sea floor are connected with a buffer cable with a buffer material interposed between them,
The other end of the chain is connected to the block.
Mooring system for small vessels. A plurality of mooring systems for small vessels according to claims 1 to 3 according to claim 1 are installed,
Configured to share submarine blocks that exist between adjacent systems,
Mooring system for small vessels.

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