JPS5947093B2 - Floating ice prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating ice prevention device disposed around the outer periphery of a conventional non-waterproof marine structure.

When attempting to use a non-waterproof offshore structure, such as a conventional floating oil rig, in icy waters, the force of flowing water may exceed the mooring capacity of the offshore structure, or the offshore structure may be destroyed by water pressure. There is a risk of

In addition, when the offshore structure is an oil drilling rig, there is a problem in that even if the mooring device of the oil rig can withstand the force of drift ice, the oil rig will move significantly and drilling operations will not be possible.

On the other hand, the structure and shape of conventional marine structures are not shaped to reduce the force of drift ice, and the influence of the force of drift ice becomes severe as the drift ice causes crushing or destruction. It is necessary to protect from

Therefore, the present invention was made to solve the above-mentioned conventional problems, and is to protect conventional non-waterproof marine structures such as semi-submersible offshore oil drilling rigs from drift ice even when used in icy areas. The purpose of the present invention is to provide a floating ice prevention device that can prevent floating ice.

That is, the floating ice prevention device of the present invention disposes a buoyant body moored to a gravity anchor by a tension cable around the outer periphery of a marine structure floating on the water surface and floats in a circular shape with excessive buoyancy. The outer wall of the body is formed into an inclined surface by bending the drift ice, and the buoyant body is divided into a plurality of pieces, and a ballast device provided on the buoyant body is configured so that only the buoyant body at a partial position can sink and float on the water surface. It is characterized by

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a side sectional view of a water-resistant buoyant body 2 provided on the outer periphery of an offshore structure 1 such as a floating oil drilling rig. , FIG. 2 is a plan view thereof, FIG. 3 is a side sectional view showing the state in which the buoyant body 2 on the side where the supply vessel 6 approaches the marine structure 1 in FIG. 1 is sunk, and FIG. 4 is a buoyant force. It is a side sectional view showing a modification of the body.

First, a conventional non-waterproof marine structure 1 is moored by multiple tension ropes 3 to a gravity anchor 4 sunk on the seabed, and is floating in a circular shape with excessive buoyancy. A floating type buoyant body 2 is disposed to surround the outer periphery of the marine structure 1 in a circular shape to constitute a floating ice prevention device.

The outer wall of this buoyant body 2 has an arrow F as shown in FIG.
A sloped surface 2a is formed so as to push and bend the drift ice 5 downward and break it, and the drift ice force of the drift ice 5 is reduced by this slope 2a, which pushes and bends the drift ice 5 downward.
Since the buoyancy body 2 itself is arranged in a circular shape, the drift ice 5 flowing in the direction of arrow F as shown in FIG.
Since the drift ice 5 moves in the leeward left-right direction along the outer circumference, the drift ice force of the drift ice 5 becomes -.

At that time, the buoyant body 2 tries to move to the leeward side due to the force of the ice, but the buoyant body 2, which is floating in a state of excessive buoyancy, is prevented from rotating by the plurality of tension ropes 3 stretched vertically.
Because it has horizontal restoring force, the drift ice force remains constant,
Stops after a small amount of movement.

Therefore, the drift ice 5 collides only with the buoyant body 2 that circularly surrounds the outer periphery of the marine structure 1, and does not directly collide with the marine structure 1 inside, so the marine structure 1 hardly moves.

Furthermore, even if the outer buoyant body 2 moves significantly due to the drift ice 5, the ice force will not directly act on the marine structure 1 as long as a sufficient distance is maintained between it and the inner marine structure 1. .

Next, when a supply vessel 6 or the like approaches the inner marine structure 1 to supply materials, the outer buoyant body 2 is divided into multiple pieces using a ballast tank 8, which is a ballast device. Using the circular buoyancy body 2, only the buoyancy body 2 at a partial position is made to sink.

At this time, the buoyant body 2 at the position of the part to be sunk is divided so that it is always on the lee side of the drift ice 5 with respect to the flowing direction F of the drift ice 5, as shown in Fig. 2, so that the remaining excess buoyancy A buoyant body 2 on the windward side floating on the water surface prevents drift ice 5 from entering and allows a supply ship 6 to pass through.

The buoyant body 2 sunk by the ballast tank 8 is the third
As shown in the figure, it is supported underwater by a plurality of support ropes 7 fixed to adjacent buoyant bodies 2.

FIG. 4 shows the deformation of the buoyant body 2, in which the upper half A is formed into an inverted triangle in side cross section, the outer wall 2' is formed into a gentle curve, and the lower half B is formed into a rectangular shape. It shows where you are.

In short, the floating ice prevention device according to the present invention has a buoyancy body moored to a gravity anchor by a tension cable and floating in a circular shape in an excessively buoyant state around the outer periphery of a marine structure floating on the water surface. The outer wall of the buoyant body is formed into an inclined surface by bending the drift ice, and the buoyant body is divided into a plurality of pieces, and a ballast device provided on the buoyant body allows only the buoyant body at a partial position to sink and float on the water surface. Because of this structure, drift ice does not directly collide with marine structures located inside the buoyancy that floats in a circular shape with excess buoyancy, so even when the marine structure is used in a drift ice area, the marine structure itself cannot be damaged. Although it does not need to be configured to be water resistant,
The outer wall of the buoyancy body, which is arranged in a circular shape under excessive buoyancy, has an inclined surface for pushing and bending the drift ice, so the drift ice is pushed downward by the slope and bent, breaking it and arranging the drift ice in a circular shape. Since the buoyancy body can be moved in the leeward left-right direction along the circumference of the buoyancy body, the amount of movement of the buoyancy body due to drift ice can be minimized.

In addition, the buoyant body is divided into multiple parts and the ballast device installed on the buoyant body allows only the buoyant body at a partial position to sink and float above the water surface, so only the buoyant body at a partial position can be lowered from the water surface. By sinking the vessel, the remaining buoyant body floating on the water surface in a state of excessive buoyancy can prevent the intrusion of drift ice while allowing ships to pass through.

Furthermore, since the buoyant body is moored to the gravity anchor by a tension cable, it can be used even in deep sea areas.

Therefore, it is possible to provide a floating type ice drift prevention device that can protect a non-waterproof marine structure from drift ice even when it is used in an icy area.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of a water-resistant buoyant body provided on the outer periphery of a marine structure according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. A side sectional view showing a state in which the buoyant body on the side where the ship approaches the marine structure is sunk, and FIG. 4 is a side sectional view of another buoyant body. DESCRIPTION OF SYMBOLS 1... Marine structure, 2... Buoyant body, 2a... Drift ice pushing bending slope, 3... Tension cable, 4... Weight type anchor, 5... Drifting ice, 8... ballast tank.

Claims (1)

[Claims] 1. A buoyant body that is moored to a gravity anchor by a tension cable and floats in a circular shape with excessive buoyancy is installed around the outer circumference of a marine structure floating on the water surface, and the outer wall of the buoyant body is bent by pushing ice drifts onto an inclined surface. A floating ice prevention device characterized in that the buoyant body is divided into a plurality of parts and a ballast device provided on the buoyant body allows only the buoyant body at a partial position to sink and float on the water surface. .