JPH0343030A - Submarine screen device - Google Patents

Abstract

PURPOSE:To maintain the function of an artificial gathering-place for fish in coast zone, sand zone and mud zone for a long period of time by laying the tip of strut of a control member consisting of a control part of flow opposing to ocean current and a strut under ground and furnishing a water path part between the control part and the bottom of the sea. CONSTITUTION:The tip part of a strut 6 of a control member 7 consisting of a control part 5 of flow opposing to ocean current and the strut 6 is laid under the bottom 1 of the sea, a water path part 8 capable of passing ocean current between the control part 5 and the bottom 1 of the sea to build constitution. Consequently, flow of tide, etc., is controlled, an eddy is generated, undulating ground is formed behind or seaweeds are retained to multiply low-layer fishes. In a sand and a mud zones, the control member is hardly laid under ground by washing and digging and maintains functions for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a seabed screen device that maintains a fish reef function for a long period of time even in coastal waters, sand, and mixed cargo.

[Subject skill]

Fishing grounds have been severely restricted by each country's WWI 200 nautical mile declaration, and coastal fishing grounds are decreasing year by year due to the effects of coastal reclamation and sewage discharged due to urban and industrial development. The construction of artificial reefs is being promoted as a means of promoting and revitalizing such coastal fisheries.

Various shapes have been proposed and used as unit reefs for conventional artificial reef construction. With these conventional fish reef blocks, the ocean floor sediment around the fish reef blocks is washed away by the currents in the sea area where they are installed, and they gradually fall over and become buried, causing the reef effect to disappear.
In addition, since a large amount of eddy energy is consumed in scouring, it is difficult to generate significant eddy energy around and behind the fish reef block, and there is a problem in that it is difficult to expect the formation of undulating ground.

Regarding this, the causes of overturning and burying of fish reef blocks, as well as the occurrence of eddies and ground formation around fish reef blocks, were clarified from the results of model experiments in aquariums. That is, as shown in FIG. 9(a), when the fish reef block 2 installed on the seabed 1 collides with the tidal current 3, part of the tidal current becomes a downward direction flow, and the fish reef block 2 is placed on the front side. Stagnation occurs in the water, and vortices are generated due to the presence of areas of large turbulence. This vortex scours the earth and sand near the bottom of the fish reef block 2, and the scoured earth and sand becomes floating sand that moves and settles. In addition, a part of the tidal current 3 turns into an upward direction flow, generates a vortex, passes above the fish reef block 2, and generates a vortex around and behind the fish reef block 2. After a certain period of time has elapsed, the fish reef block 2 falls over, as shown in Figures b and c.

It was found that the fish reef block 2 was buried and no longer functioned as a fish reef block 2, and that no sand pool could be expected to form due to the sedimentation effect of suspended sand generated by scouring after being buried. Regarding the occurrence of eddies around the fish reef block 2, the current velocity distribution was measured using a hot wire current meter, and the occurrence of eddies was determined. According to this, vortices that promote scouring and vortices generated by upward diversion currents were generated near the bottom of fish reef block 2, and almost no vortex generation could be confirmed in other locations. After burial, no vortices were generated at all, and visual inspection of the ground formation revealed that
Suspended sand generated by scouring moved and settled, creating sand pools 4 in several places, but there was no ground stirring effect due to vortex energy. After burial, sand pool 4 gradually disappeared and the ground shifted to flat ground.

[Problem to be solved by the invention]

This invention was made by paying attention to the above-mentioned problems. Its purpose is to control the flow of currents, etc., generate eddies, form undulating ground behind it, or retain seaweed to encourage the proliferation of bottom fish. Our goal is to propose a submarine screen device that can maintain its functionality over a long period of time.

[Means to solve the problem]

The submarine screen device according to the present invention has a control member having a flow control section facing the ocean current and a support supporting the control section, the tip of the support being buried in the seabed. It is characterized by forming a water passage between it and the seabed through which ocean currents can pass.

〔Example〕

(Example 1) This submarine screen device has a flow control unit 5 facing the ocean current.
A control member 7 consisting of a pillar 6 and a support pillar 6 is constructed by burying the tip of the pillar 6 in the seabed 1, and providing a water passage part 8 between the control part 6 and the seabed 1 through which ocean currents can pass. .

The control member 7 includes a cylindrical body 9 (15 cmφ, length 300 CI+) made of glass fiber reinforced synthetic resin (FRP) and a column 6 (
15c+*φ, length 700a*) in a ratio of 2 and 1, one end side edge aligned in a straight line and parallel, and two sets of FRP reinforcing plates arranged in pairs on both sides 10.10 are fastened together to form the control section 5 and to allow the support column 6 to protrude. This member 7 has a width of 125 cm, and the screen device built on the ocean floor has a height of 400 CI (
Embedded portion 3000), the area of the control section 5 is width 125c+
+X height 300cm = 37.500cffl, water flow section 8
The area is width 87.5cm x height 100cm = 875
0c4, and the area ratio between the water flow part surface and the control part surface is 23.3.
%Met.

Multiple units of this screen device were installed in series on the ocean floor in a sandy ocean at a depth of 8 m. Approximately one year later, a wide area of undulating ground had formed behind the screen device, and it was observed that benthic fish such as curry flounder were gathering there.

The area of the water passing portion relative to the control portion surface is preferably in the range of 5% to 80%. If it is less than 5%, suspended sand will pass through backwards.
<, If it exceeds 80%, it becomes impossible to control flows such as ilI flow, and it becomes difficult to generate vortices. More preferably, it is 10% or more and less than 70%.

(Example 2) FIGS. 2(a) and 3 show the control member 7 used in this submarine screen device, and the cylindrical body 11 made of FRP.
Alternatively, it consists of a control section 5 made of a triangular cylindrical body 12 and a support 6 made of an FRP lined steel pipe inserted into the control section 5 and fastened thereto.

Figures 2(b) and (C) show the control member 7 shown in Figure 2 with the tip of the support column 6 buried in the seabed 1;
This is an undersea screening device built next to the sea. When the seabed structure on which this device is installed is hit by the tide fL3,
A part of the tidal current 3 becomes a downward diversion current, generating a vortex, and scours the earth and sand near the lower end of the control section 5. Sediment moves and settles as suspended sand. After a certain period of time, a water passage 8 is formed between the seabed l and the control unit 5, as shown in FIG. Move to the back of the street.

In addition, the tidal current 3 that has become an upward direction-changing flow generates a vortex and moves backward, and the vortices generated by both the upper and lower direction-changing flows combine to form a large vortex at the rear of the screen device.

Regarding these matters, the flow velocity distribution was measured using a hot wire anemometer to determine the occurrence of vortices.

According to this, a vortex that promotes scouring is generated near the bottom of the control part 5, and when the water passage part 8 formed by scouring reaches a certain depth, the scouring stops, and the vortex is generated in the water passage part 8. I could see it moving backwards via 8. In other words, it was confirmed that the vortices generated by the upward and downward diverting flows are added at the rear, resulting in large vortex energy. Also, check the ground formation status by visual inspection. As a result, the suspended sand generated by scouring moved and settled, forming several sand pools 4. After the scouring stopped, the ground was stirred by the influence of large vortex energy behind the scouring, and the scouring continued. It was found that undulating ground was formed by the synergistic effect of vortex energy and vortex energy.

In addition, since the pillars 6 are buried in the seabed 1, they are resistant to overturning or burying due to scouring, and it has been demonstrated that the reef performance can be maintained for a long period of time.

(Example 3) The control members 7 shown in Fig. 4.5.6 are each made of FRP.
A plurality of FRP-lined steel pipe supports 6 are attached to the control unit 5, which is a cylindrical body 11° with a large number of through holes 14 formed by winding a 1m triangular cylinder 12 or a strip 13 in a spiral shape.
The installation is configured.

These control members 7 can also function as a fish reef by embedding supports in the seabed to create a seabed screen device in the same way as the control members of the second embodiment.

(Embodiment 4) The control member 7 shown in FIG. 7 includes a control part 5 having a triangular cross section with an enlarged downward opening formed by joining two FRP horizontal lattice plates 15 on one side, and supports attached to both ends of the control part 5. It consists of 6.6. The plate body 15 has a large number of horizontally elongated through holes 14 between the lattices.

The control member 7 in FIG.
It consists of a control part 5 which has a trapezoidal cross section with an enlarged downward opening and is made by assembling vertical and horizontal lattice plates 16 made of P, and four pillars 6 attached to its four corners. The vertical and horizontal lattice plate body 16 of this control member 7 has a width of 300 cm, a height of 400 aa, and a through hole size of 30 cm.
cm x 30 cm, with a trapezoidal inclination angle of 60', and the strut 6 opened an FRP lined steel pipe with a diameter of 15 cm and a length of 600 cm.

The control member shown in Fig. 8 was placed in the breaking wave area of open ocean sandy ground at a depth of 7 c + e, and the tip of the support column 6 was placed 200 cm into the seabed ground.
Buried and erected, with a height of approximately 154cm between the seabed and the control section.
A seabed screening device was constructed by installing a water flow section of 1.5 m. After about a year, we observed that seaweed had been caught in the water passage below the control, and turban shells, abalone, etc. had gathered around it as food. Additionally, this screen device was extremely stable, with almost no subsidence, and maintained its function as a nurturing reef for a long period of time.

The control section of the submarine screen device of this embodiment is made up of a plate having a large number of slanted through holes, and when an ocean current hits it and passes through the through holes, floating seaweed is caught and captured. At the same time, the ocean current that hits the control unit generates a vortex in front of it, and the floating seaweed is caught in the vortex and stays in front of the screen device while moving in a circular motion. It becomes easier. If the angle of inclination is less than 30° or more than 70°, it will be difficult to get caught, so it is preferably 30° or more and less than 70°.

In addition, when the speed of the ocean current exceeds a critical value, the seaweed that accumulates in front of the screen device will fall backwards over the top of the screen device, and will be pulled back into the screen device by the backflow of the bottom layer and remain in the screen while moving in a circular motion. However, seaweed also becomes caught in the plate with the sloping holes at the rear.

In the above embodiments (1, 2, 3, 4), the material of the member 4
Although the shape and shape were specified, the material used is not limited to FRP.
You can freely select and use concrete, steel, etc. Further, regarding the shape, members having an elliptical cross section, a hexagonal shape, etc. can be used as appropriate.

〔Effect of the invention〕

The present invention is as described above, and this submarine screen device generates eddies in ocean currents, forms undulations on the ground behind the device, retains seaweed, and cultivates bottom layer seafood.
Exercises the function of proliferation. In addition, it can function for a long time without sinking or burying.

[Brief explanation of drawings]

1 to 8 show embodiments of this invention, and the first
The figure is a perspective view showing a partial cross section of the submarine screen device of (Example 1), and FIGS. 2(a) and 3 are respectively (Example 2).
), Figures 2(b) and (C) are perspective views of a submarine screen device in which the control member of Figure 2(a) is built-in, and Figures 4.5 and 6 are respectively ( FIG. 7.8 is a perspective view of the control member of Example 3), and FIGS. 9A, 9B, and 9C are perspective views of the control member of Example 4, respectively.
is a vertical cross-sectional view showing the process of overturning and burying a conventional fish reef block. 1... Seabed, 2... Fish reef block, 3
...Ocean current, 4...Sand pool, 5...
...Control part, 6...Strut, 7...Control member, 8...Water passage part, 9...Cylinder body,
lO...Reinforcement plate, 11...Cylindrical body, 1
2... Triangular cylinder, 13... Strip, 14...
...Through hole, 15...Horizontal lattice plate, 16...
... Vertical and horizontal lattice plate.

Claims (1)

[Claims] (1) A control member that has a flow control section facing the ocean current and a column that supports this control section is constructed by burying the tip of the column in the seabed, and the ocean current flows between the control section and the seabed. A submarine screen device characterized by forming a water passage through which water can pass.