JPS59227589A - Method of and device for preventing floating body from rolling - Google Patents

Abstract

PURPOSE:To prevent a semi-submerged type structure from being affected by waves, by providing such an arrangement that a movable plate is coupled to a column in the structure through a gimbal type coupler to absorb oscillation due to waves. CONSTITUTION:A movable plate 3 consisting of an annular floating body subjected to waveforce, is attached, through a gimbal type coupler 4, to a stationary plate 2 secured to a column 1 in a semi-submerged type structure. The above- mentioned coupler 4 comprises a ring-like frame in which a rotary shaft 5 rotatably journalled by bearings 7 is disposed by means of a spring and a damper. The annular foating body absorbs oscillating motion due to incoming waves so that the structure is prevented from being affected by waves.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for preventing a floating body such as a floating marine structure that moves by the wave force of a predetermined wave from moving from side to side.

Conventionally, various devices have been devised to prevent the horizontal sway of a floating body, and various shapes have been proposed to reduce the vertical sway of a floating body, but there is no known means for preventing the horizontal sway of a floating body. do not have.

For this reason, in the past, mooring cables were used to prevent the floating body from shaking from side to side or drifting in waves, but mooring cables must be made of fairly strong materials because they are subject to large repeated tensions. However, as the mooring ropes are used alone, their strength deteriorates significantly due to corrosion caused by seawater, etc., so there is a safety problem with using mooring ropes alone.

In view of the above-mentioned points, it is an object of the present invention to provide a method and apparatus for preventing a floating body from swaying laterally and reducing drifting during waves.

In order to achieve the second object, the structure of the method for preventing side-to-side sway of a floating body of the present invention is to install an object having a certain mass and volume on the side of a buoyant structure based on the wave force of the external world. generate waves based on rotational shaking about the horizontal axis,
In addition, the structure is characterized in that the phase and amplitude of the generated waves are controlled so as to cancel out the wave forcing force acting on the structure, thereby canceling out the horizontal sway of the structure.

The structure of the floating body sway prevention device of the present invention includes a structure having buoyancy, a movable plate that receives wave force, and a connector connecting the side of the structure and the movable plate, The connecting portion of the coupler is configured such that the horizontal sway of the movable plate coupled with the rotational sway of the movable plate with respect to the horizontal axis cancels the lateral sway of the structure caused by wave force. It is characterized by comprising a spring and a damper for controlling the rotational swing of the movable plate.

Therefore, according to the present invention, objects having a certain mass and volume, such as the structure and the movable plates, move relative to each other in the waves, that is, the structure and the movable plates, etc. achieve horizontal sway and rotational sway. By generating a movement and adjusting the phase and amplitude of this coupled movement using communication means such as a coupler, it is possible to prevent side-to-side shaking at a predetermined location, and also to move the movable plate etc. using wave energy. Since the waves are created by the waves, drifting of the structure can be reduced. in this way,
According to the present invention, it is possible to prevent the floating body from swaying from side to side and drifting due to predetermined waves, and in particular, it is possible to dramatically improve the movement performance of the floating body as a floating marine structure in waves.
In addition, mooring devices can be eliminated or
Or it can be significantly simplified.

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a buoyant structure, mainly a column portion of a semi-submersible marine structure. Reference numeral 2 denotes a fixed plate fixed to the side surface of the structure 1, Lo is a movable plate consisting of an annular floating body that receives wave force, which will be described later, and 4 is a gimbal connecting the fixed plate 2 and the movable plate 3 of the structure 1. It is a type coupler. and the coupler 4
has a ring-shaped frame as shown in Figure 2,
Two rotation shafts 5 fixed horizontally in the front and rear direction inside the body.
and two rotating shafts 6 fixed horizontally and horizontally on the outside of the body, each rotating shaft 5 is supported by a bearing 7 provided on the fixed plate 2, and each rotating shaft 6 is It is supported by bearings 8 provided on each movable plate B.

Moreover, each rotating shaft 5 is rotatably supported by a bearing 7 via a spring and damper described later, and each rotating shaft 6 is also rotatably supported by a bearing 8 via a similar spring and damper. has been done.

The spring and damper provided between the rotating shaft 5 and the bearing 7 will now be explained with reference to FIGS. 3 and 4.

(5) In the example shown in Figure 3, spring 9 is a coil spring (all springs).
One end is fixed to the rotating shaft 5, the other end is fixed to the bearing 7, and the spring 9 controls the rotational force of the rotating shaft 5. That is, the spring 9 generates a restoring force in proportion to the rotation angle of the rotating shaft 5.

Further, in the example shown in FIG. 4, the damper 10 is of a hydraulic damper type consisting of a hydraulic cylinder device, the tip of the piston rod 11 is fixed to the rotating shaft 5, the cylinder 12 is fixed to the bearing 7, and the damper The device 10 is designed to generate a resistance force in proportion to the rotational speed of the rotating shaft 5.

Although the spring 9 and damper 10 provided between the rotating shaft 5 and the bearing 7 have been described in FIGS. 6 and 4, a similar spring is also provided between the rotating shaft 6 and the bearing 8. and an attenuator.

Next, the operation of the floating body rocking protection device constructed as shown in FIGS. 1 to 4 will be explained.

Due to waves in the direction of arrow 13 in Fig. 1, the structure (6) 1 and the movable plate 3 are subjected to wave pressure, and the structure (6) 1 and the movable plate 3 are subjected to wave pressure, and the structure (6) 1 and the movable plate 3 each undergo downward shaking, sideways shaking, and rotational shaking (vertical shaking). ). Therefore, if the structure 1 and the movable plate 6 are axially symmetrical with respect to the vertical axis, it can be considered that vertical shaking occurs independently of other movements, so that the main rapid motion occurs between left-right shaking and rotational shaking.

Here, two cases are considered: a case where rotational shaking of the structure 1 is allowed, and a case where the structure 10 is allowed to rotate.
The effect will be explained separately for the case where rotational shaking is not required.

When the structure 1 is allowed to rotate and sway, the rotation shaft 5 sways left and right as a result of the rotational sway of the structure 10 coupled with the left and right sway. Here, when the rotational shaking of the movable plate 3 is coupled to the rotational shaking and left-right shaking of the structure 1 via the spring 9 of the coupler 4 and the damper 10, the rotation due to the rotational shaking and left-right shaking of the structure 1 The horizontal shaking of the shaft 5 cancels each other out, and the horizontal shaking of the rotating shaft 5 is prevented.

When it is not necessary to allow rotational sway of the structure 1, for example, when only one column of a semi-submersible floating marine structure is taken up as a floating body (d, that column is subjected to wave forcing of left and right sway. So, if the forcing force due to the rotational sway of the movable plate A is added to the lateral swaying force of the column via the coupler 4, as in the case of ``2 series,'' it will cancel out the wave forcing force of the lateral swaying of the column. , the left-right swing of the column, that is, the left-right swing of the structure 1 is prevented.

FIG. 5 shows another example of a spring having the same effect as the spring 9 shown in FIG. The rack 15 is adapted to slide along the pedestal 16. In other words, the rotational movement of the rotation shaft 5 causes the pinion 1 to
4 to the spring 9 via the rack 15, the spring 9 generates a restoring force proportional to the rotation angle of the rotating shaft 5, and controls the rotational force of the rotating shaft 50.

FIG. 6 shows another example of an oil damper having the same effect as the damper 10 shown in FIG. The rotating shaft 5 is configured to slide, and the rotating shaft 5 has fins 19 provided radially with a gap from the inner surface of the casing 17. Therefore, attenuator 10
The resistance force is generated in proportion to the rotational speed of the rotating shaft 5.

FIG. 7 shows a second embodiment of the present invention corresponding to FIG. 1, in which the movable plate 6 is provided so as to be located underwater. By submerging the movable plate 6 in this way,
Wave loads such as wave impact loads applied to the movable plate 3 can be reduced.

FIG. 8 shows a sixth embodiment of the present invention, in which the structure 1
The movable plate 3 is a connected raft type, and a movable plate 6 is connected to the side of the structure 1 via a coupler 4. The coupling portion of the coupler incorporates the spring and damper described above.

9 and 10 show a fourth embodiment of the present invention, and FIG. 11 shows a fifth embodiment of the present invention, both of which show a thick circular shape fixed to the structure 1. The fixed plate 2 has a number of air chambers 20 and a number of water chambers 21 opening downward, and a piston 22 is provided between the upper air chamber 20 and the lower water chamber 21 so as to be slidable up and down. and has ``1''
The end is fixed to the top inner surface of the air chamber 20, and the lower end is fixed to the piston 2.
2, a coil spring 23 fixed to two surfaces, an air pipe 24 provided in communication with the top of the air chamber 20, and the air pipe 24.
It has an air flow rate adjustment valve 25 provided in the middle. That is, in these fourth and fifth embodiments,
Since the ice block existing inside the water chamber 21 has a certain mass and volume, it plays a role similar to the above-mentioned movable plate 3, and the coil spring 23 plays the role of the above-mentioned spring 9, and the air pipe 24 and valve 25 serve as the attenuator 10 described above.

Note that in the first and second embodiments described above, the coupler 4
Although a gimbal type is used as an example, if the direction of the incident wave is constant, only one direction of the rotation axes 5 and 6 may be used.

As is clear from the above description, according to the present invention, waves are generated on the side of a structure having buoyancy by an object or substance having a certain mass and volume, and the wave causes the movement of the object or substance. By using the coupled motion between the structure and the structure, it is possible to cancel out the horizontal sway at a specified position due to the rotational sway and side-to-side sway of the structure, or to eliminate the wave forcing force of lateral sway in a structure whose rotational sway is restrained. By doing so, it is possible to prevent the structure from swaying from side to side due to a given wave during waves, and furthermore, it is possible to prevent or reduce drifting of the structure, so that the mooring device can be omitted or significantly simplified. be able to. Further, according to the device of the present invention in which the structure and the movable plate are connected by a coupler having a spring and an attenuator for controlling the rotational swing of the movable plate in the connecting part, the left and right sides of the structure in response to a predetermined wave are Since shaking can be reliably prevented, the motion performance of structures such as floating marine structures in waves can be dramatically improved.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG.
2 is a sectional plan view taken along cutting line A-A in FIG. 1, FIG. 3 is an enlarged sectional front view of the spring provided in the coupler in FIG. 1, and FIG. 4 is a front view of the embodiment. 5 is an explanatory diagram of another embodiment of the attenuator, FIG. 6 is an explanatory diagram of another embodiment of the attenuator, and FIG. 7 is an explanatory diagram of another embodiment of the attenuator. FIG. 8 is a front view of the second embodiment, FIG. 8 is a perspective view of the third embodiment, FIG. 9 is a partially cutaway front view of the fourth embodiment, and FIG. 10 is a cross section taken along cutting line B-B in FIG. 9. The bottom view and FIG. 11 are partially cutaway front views of the fifth embodiment. 1...Structure, 300. Movable plate, 41. . Connector・9...Spring・10...Attenuator. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. Generating waves based on rotational shaking about a horizontal axis by an object having a certain mass and volume on the side of a buoyant structure based on wave forcing from the outside world, and A method for preventing horizontal sway of a floating body, characterized in that the phase and amplitude of the generated waves are controlled so as to cancel out the wave forcing force acting on the structure, thereby canceling the lateral sway of the structure. 2. It consists of a structure with buoyancy, a movable plate that receives wave force, and a connector connecting the side of the structure and the movable plate, and the connecting part of the connector has a horizontal axis. a spring and an attenuator that control the rotational oscillation of the movable plate so that the lateral oscillation of the movable plate coupled with the rotational oscillation of the movable plate cancels the lateral oscillation of the structure caused by wave force; A device for preventing side-to-side sway of a floating body, characterized by comprising: