JPH047402A - Structure for reducing force of shock wave on water surface structure - Google Patents

Abstract

PURPOSE:To sharply reduce the force of shock waves acting on a water-surface structure by providing walllike protruding pieces extended downward to an oblique plate and disturbing the condition of the water surface below the oblique plate when the position at which the water surface intersects the oblique plate becomes lower due to a lowering wave front. CONSTITUTION:Walllike protruding pieces 16 extended downward are provided to the lower surface 8 of the oblique plate 7 of a wave dissipation jetty in the vicinity of the position 13 where the water surface intersects the lower surface 8 when the water is calm. When the position 13 goes down due to a lowering wave front, the pieces 16 disturb the water surface below the plate 7 so as to prevent the water surface from becoming nearly parallel to the plate 7. Even when the water level goes up below the plate 7 thereafter, the collision of the water surface with the lower surface of the plate 7 in a slope condition can be prevented and the force of the shock waves acting on the plate 7 can be reduced. Therefore, the force of shock waves to a water-surface structure can be reduced by about 40% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shock wave force reduction structure for a structure installed on a water surface.

[Background Art] In recent years, various studies have been made on installing structures on the surface of water such as the ocean.

A wave-dissipating levee will be described as an example of such a water surface installation structure with reference to FIGS. 5 and 6.

In the figure, 1 is the still surface of seawater, 2 is the wave, and 3 is the progress of wave 2.
4 is the oil side behind the traveling direction 3, 5 is the shore side in front of the traveling direction 3, and 6 is the seabed.

7 is a swash plate having an inclined lower surface 8 with an upward slope relative to the traveling direction 3 of waves 2, in which the lower part of the oil side 4 is located below the still water surface 1 and the lower part of the shore side 5 is located above the still water surface 1; A sleeve-shaped leg portion 10 supporting the plate 7 is passed through the leg portion 9 and placed on the seabed 6.
This is a steel pipe pile driven into.

(2) 1 is a wave passing above the swash plate 7, and 12 is a wave passing below the swash plate 7.

The swash plate 7 is installed, for example, on a coast facing the open ocean or near the sea surface offshore.

In a wave-dissipating bank having such a swash plate 7, a wave 11 passing above the swash plate 7 is broken on the swash plate 7, becomes a reflected wave by the swash plate 7, and the energy of the wave 2 is dissipated. and,
The wave 11 that has passed above the swash plate 7 interferes with the wave 12 that has passed below the swash plate 7, and the energy of the wave 2 is further dissipated, thereby causing wave dissipation.

[Problems to be Solved by the Invention] However, water surface installation structures such as the above-mentioned breakwaters have the following problems.

That is, as shown in FIG. 7, on the shore side 5 of the swash plate 7, the water surface intersection position 13 between the lower surface 8 of the swash plate 7 and the sea surface fluctuates up and down with the vertical movement of the wave surface, but the water surface intersection position When the swash plate 13 descends, the shape of the water surface below the swash plate 7 may become a slope substantially parallel to the swash plate 7.

Then, when the water level below the swash plate 7 rises, the swash plate 7
The water surface, which is sloped approximately parallel to the lower surface 8, rises rapidly and collides with the lower surface 8 of the swash plate 7 at the same time, causing the swash plate 7 to generate a large shock wave upward and toward the oil side 4. You will receive a force of 14.

As described above, since the large shock wave seal 4 acts on the swash plate 7, there is a problem that the swash plate 7 must be made strong enough to withstand the shock wave force 14, resulting in high cost. Even when the strength of the swash plate 7 is increased, there is a problem that the swash plate 7 may be damaged by the shock wave force 14 after long-term use.

In view of the above-mentioned circumstances, the present invention provides a shock wave force reduction structure for water surface installation structures that can reduce the shock wave force acting on various water surface installation structures such as the swash plate of a wave-dissipating levee. It is something.

[Means for Solving the Problems] The present invention provides a water surface installation structure having a lower surface having an upward slope with respect to the direction of wave propagation, with a part below the still water surface and the other part above the still water surface. This invention relates to a shock wave force reduction structure for a structure installed on a water surface, characterized in that a protrusion extending downward is provided on the lower surface of the structure installed on a water surface in the vicinity of a water surface crossing position in still water.

[Function] The downwardly extending protrusion installed near the water surface crossing position of the water surface installation structure in still water disturbs the water surface shape on the lower surface of the water surface installation structure, causing the water surface shape or the water surface installation structure to become sloped. This prevents the surface from forming a slope that is substantially parallel to the lower surface.

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

FIGS. 1 and 2 show one embodiment of the present invention, and parts in the figures with the same reference numerals as in FIGS. 5 to 7 represent the same parts.

In the vicinity of the water surface intersection position 13 in still water of the inclined lower surface 8 of the water surface installation structure 15 such as the swash plate 7 of a wave dissipating bank, there is a groove extending downward in the width direction 25 of the swash plate 7, that is, the traveling direction 3 of the waves 2. A wall-shaped protrusion 16 is provided that continues in a direction perpendicular to the .

In this way, the water surface crossing position 1 of the lower surface 8 of the swash plate 7 in still water
By providing a wall-shaped protrusion 16 extending downward near 3, when the wave surface descends and the water surface crossing position 13 lowers,
The protrusions 16 disturb the shape of the water surface below the swash plate 7 and prevent the water surface from becoming a sloping surface substantially parallel to the swash plate 7, so that even if the water surface below the swash plate 7 rises thereafter, Since the water surface becomes sloped and does not collide with the lower surface of the swash plate 7 all at once, the shock wave force 14 acting on the swash plate 7 can be significantly reduced to approximately 40% or more.

FIG. 3 shows another embodiment of the present invention, with respect to the swash plate 7, a water surface intersection position 18 on a still water surface 17 at high tide, a water surface intersection position 20 on a still water surface 19 at low tide, and both water surface intersection positions. 18.Protrusions 22, 2 are provided at intermediate positions 21 and 20, respectively.
3.24 is attached, and in this way, the shock wave force 14 acting on the structure installed on the water surface can be significantly reduced, as in the previous embodiment, regardless of changes in the tide level.

Figures 4(a) to (e) show protrusions 1B, 22, 23.2
4 (7) This is an example, and Fig. 4 (a) shows a discontinuous part 2 in a part.
6, the piece in Figure 4 has a wrap part 27 formed in part, and Figure 4 (C) shows small protrusions 28 arranged in a dotted line, and the piece in Figure 4 is the whole piece. FIG. 4(e) shows an arrangement having a wavy shape, in which inclined small protrusion pieces 29 are arranged with a lap portion 30 in some parts.

Even in this case, the shock wave force 14
can be reduced.

It should be noted that the shock wave force reduction structure of the water surface installation structure of the present invention is not limited to the above-mentioned embodiments, the water surface installation structure is not limited to a wave-dissipating levee, and the shape of the protrusion may be arbitrary. Of course, various changes may be made without departing from the gist of the invention.

[Effects of the Invention] As explained above, according to the shock wave force reduction structure of the water surface installation structure of the present invention, a protrusion that extends downward is provided near the water surface crossing position on the bottom surface of the water surface installation structure in still water. Therefore, the protrusion disturbs the shape of the water surface on the lower surface of the structure installed on the water surface,
The shape of the water surface is prevented from becoming a slope that is almost flat with the bottom surface of the structure installed on the water surface, and as a result, the shock wave force applied to the structure installed on the water surface when the sloped water surface collides with the bottom surface of the structure installed on the water surface at the same time is reduced by approximately 40%. It is possible to achieve an excellent effect of being able to reduce the amount by more than 100%.

[Brief explanation of drawings]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a view of FIG. 1 seen from below, FIG. 3 is a side view of another embodiment of the present invention, and FIG. (C) (Small (e) is a diagram showing an example of a protrusion, Figure 5 is a perspective view of a breakwater as a structure installed on the water surface,
6 is a side view of FIG. 5, and FIG. 7 is a side view substantially similar to FIG. 6, illustrating the shock wave force acting on the wave-dissipating bank. In the figure, 1, 17, 19 is the still water surface, 2 is the wave, 3 is the traveling direction of the wave 2, 4 is the oil side behind the traveling direction 3, 5 is the shore side in front of the traveling direction 3, 7 is the water surface installation structure 15 8 is the lower surface of the swash plate 7, 13, 18.20 is the water surface crossing position, 1B,
22, 23, and 24 indicate protrusions.

Claims (1)

[Claims] 1) In a water surface installation structure that has a lower surface that is sloped upward with respect to the direction of wave propagation, with a part below the still water surface and the other portion above the still water surface, the lower surface of the water surface installation structure in still water A shock wave force reduction structure for a structure installed on a water surface, characterized in that a protrusion extending downward is provided near a water surface intersection position.