JP6888792B1 - Scour prevention structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scouring prevention structure capable of exhibiting a high scouring prevention effect by a structure in which an upper portion of a suction prevention layer having a suction prevention function is covered with a coating layer having a wave power dispersion function. SOLUTION: The scouring prevention structure 1 of the present invention is formed by filling a basket 10 with a filling material 20, the basket 10 includes a basket main body 11 and an inner basket 12, and the basket main body 11 has a bottom net. The inner cage 12 is composed of a bottom panel 12b, a side panel 12a, and a lid panel 12c, and the mesh size of the inner cage 12 is smaller than the mesh size of the cage body 11. The filling material 20 is composed of a coarse-grained material 21 and a fine-grained material 22, and the fine-grained material 22 filled in the inner cage 12 constitutes an suction prevention layer La and is filled on the lid surface panel 12c in the cage main body 11. The coating layer Lb is formed of the coarse-grained material 21. [Selection diagram] Fig. 1

Description

The present invention relates to a scouring prevention structure, and in particular, a scouring capable of exhibiting a high scouring prevention effect by a structure in which the upper part of the suction prevention layer having a suction prevention function is covered with a coating layer having a wave power dispersion function. Regarding the prevention structure.

It is known that in structures installed underwater or near water such as breakwaters and wave-dissipating blocks, the skeleton acts as a resistor for water flow, generating a vortex around it and scouring the earth and sand around the foundation. ing. If the foundation is scoured, the stability of the structure will be impaired, which may cause damage such as subsidence, inclination, and collapse of the structure.
Patent Documents 1 and 2 disclose a scouring prevention technique in which a futon basket formed by assembling wire mesh panels in a box shape is laid under the foundation of a structure or arranged around the foundation to cover the foundation. ing.

JP-A-2002-4244 Jikkenhei 1-120519

When installing the scouring prevention structure in a place with large wave power such as a breakwater, in order to effectively disperse and reduce the wave power, a stone with a large particle size such as split chestnut stone is used as the filling material. , The porosity per occupied volume is designed to be large.
However, if the particle size of the filling material is increased, the difference from the particle size of the sand on the bottom of the water becomes large, so that the sand directly under the bottom surface is sucked out through the voids of the filling material, and the scouring prevention structure sinks or tilts. May cause.
When the scouring prevention structure sinks, the arrangement of the scouring prevention structure is disturbed, and it becomes impossible to secure the scouring prevention function originally designed, or the original scouring prevention is caused by deformation of the frame or damage to the wire mesh. It is possible that the function will be impaired.
Further, when the scouring prevention structure is used as the basis of the wave-dissipating block or the like, the meshing of the upper wave-dissipating blocks becomes poor, which may cause scattering or breakage.

The scouring prevention structure of the present invention is formed by filling the inside of a futon cage with a filling material, and the duvet cage includes a cage body and an inner cage configured inside the cage body, and the cage body is a bottom net. The inner basket consists of a bottom panel attached to the inner surface of the bottom net and four side panels attached to the lower part of the inner surface of the four side nets. It consists of a lid panel covering the upper part of the four side panels, and the mesh size of the inner basket is smaller than the mesh size of the basket body, and the filling material has a coarse grain material and a particle size larger than that of the coarse grain material. The suction-preventing layer is formed by the fine-grained material composed of small particles and the fine-grained material filled in the inner cage, and the suction-preventing layer is covered with the coarse-grained material filled on the lid panel in the cage body. It is characterized in that a coating layer is formed.

In the scouring prevention structure of the present invention, the inner cage may be made of a grid-like resin geogrid.

In the scouring prevention structure of the present invention, the particle size of the coarse-grained material may be in the range of 100 mm to 300 mm, and the particle size of the fine-grained material may be in the range of 20 mm to 100 mm.

The scouring prevention structure of the present invention may be a wire mesh panel in which the bottom surface net, the side surface net, and the lid surface net are formed by extending a diamond-shaped wire mesh inside the frame.

In the scouring prevention structure of the present invention, the diamond-shaped wire mesh may be made of a wire rod obtained by coating a zinc-aluminum alloy-plated steel wire with a resin.

The scouring prevention structure of the present invention may include a restraint wire connecting two facing side nets.

The scouring prevention structure of the present invention effectively disperses wave power by a coating layer having a large porosity to prevent scouring of the bottom of the water, and at the same time, sand sucked into water from directly under the bottom surface is made of fine-grained material. By trapping in the void, both the scouring prevention function and the suction prevention function can be achieved at the same time.
In addition, by using the voids in the covering layer as a habitat for fish and shellfish, it is possible to exert a fishing reef function.

Explanatory drawing of the scour prevention structure which concerns on this invention. Explanatory drawing of the futon basket. Explanatory drawing of the use state of the scour prevention structure which concerns on this invention.

Hereinafter, the scouring prevention structure of the present invention will be described in detail with reference to the drawings.

[Bridge scour prevention structure]
<1> Overall configuration (Fig. 1).
The scouring prevention structure 1 is a structure that prevents scouring of the ground on the bottom or the waterside.
In this example, an embodiment in which the scouring prevention structure 1 is laid on the foundation of the wave-dissipating block will be described. The scouring prevention structure 1 may also be installed on the foundation of a quay, a breakwater, a wind power generation facility, or the like.
The scouring prevention structure 1 is formed by filling the inside of the futon basket 10 with the filling material 20.
The scouring prevention structure 1 has a suction prevention layer La that prevents sand from being sucked out from the bottom of the water, and a wave power dispersion function and a suction prevention layer La suppression function by combining the structure of the futon cage 10 and the type of filling material 20. Consists of a two-layer structure of the coating layer Lb having.
In this example, the size of the scouring prevention structure 1 is 2 m in width × 3 m in length × 1 m in height.

<2> Futon basket (Fig. 2).
The futon basket 10 is a box body that houses the filling material 20 inside.
The futon basket 10 includes a basket body 11 and an inner basket 12 configured inside the basket body 11.
The mesh size of the inner cage 12 is smaller than the mesh size of the cage body 11.
In this example, the mesh size of the diamond-shaped wire mesh of the cage body 11 is 150 mm, and the mesh size of the geogrid of the inner cage 12 is 40 mm on each side.
Here, the mesh size of the rhombic wire mesh means the length of one side of the space quadrilateral surrounded by the column lines, and the mesh size of the geogrid is not the mesh size but one side of the space quadrilateral surrounded by strands. Means the length of.

<2.1> The main body of the basket.
The basket body 11 is a box made of wire mesh.
The basket body 11 is formed by assembling a four-sided side net 11a, a bottom net 11b, and a lid net 11c in a box shape.
In this example, the side net 11a, the bottom net 11b, and the lid net 11c are wire mesh panels in which a diamond-shaped wire mesh is spread inside a rectangular frame line, respectively.
However, the four side nets 11a do not necessarily have to be independent members. For example, two side nets 11a on both sides in the width direction of the cage body 11 are foldably connected to the bottom net 11b. It may be a structure.
In this example, a wire rod (IR coated plated steel wire) in which zinc aluminum alloy plated steel wire is coated with polyethylene ionomer resin is used as the material for each frame wire and diamond-shaped wire mesh.
However, the material such as the frame wire is not limited to this, and may be, for example, a zinc-aluminum alloy-plated iron wire, a zinc-plated iron wire, or the like.

<2.2> Inner basket.
The inner basket 12 is a box body that houses the fine-grained material 22.
The inner basket 12 includes a side panel 12a attached to the lower part of the inner surface of the side net 11a, a bottom panel 12b attached to the inner surface of the bottom net 11b, and a lid surface panel 12c covering the upper part of the four side panels 12a. Consists of.
The side panel 12a has substantially the same width as each side net 11a of the cage main body 11, and the height is smaller than the side net 11a. In this example, the height of the side panel 12a is half that of the side net 11a.
The bottom panel 12b and the lid surface panel 12c have substantially the same width and length as the bottom surface net 11b and the lid surface net 11c of the cage main body 11.

<2.2.1> Material for the inner basket.
In this example, a resin geogrid is used as the material of the inner basket 12.
A geogrid is a civil engineering material formed by connecting components having tensile resistance in a grid pattern to form a sheet. The geogrid is a member having high strength, excellent creep characteristics, weather resistance, impact resistance, abrasion resistance, etc., and is suitable as a material for the inner basket 12 of the present invention.
In this example, as the geogrid, a product in which a core material made of fibers made of high-strength polyester resin (PET) is coated with polypropylene resin (PP) to form a grid pattern is adopted. Examples of such products include "TRIGRID (registered trademark)" manufactured by Okasan Ribic Co., Ltd.
As described above, the optimum material for the inner cage 12 is geogrid, but the material is not limited to this, and may be, for example, a wire mesh having a mesh size smaller than the mesh size of the cage body 11.

<2.3> Connecting material.
The connecting member 13 is a member that connects the side net 11a, the bottom net 11b, and the lid net 11c of the cage body 11 to each other.
In this example, a connecting coil formed by winding a hard steel wire into a coil is used as the connecting material 13.
For example, by winding a connecting coil around the vertical wires of two adjacent side nets 11a, the two side nets 11a can be easily and surely connected.
The connecting material 13 is not limited to the coil material, and may be another known connecting means such as a wire number or a clip.

<2.4> Restraint wire.
The restraint wire 14 is a member that restrains the space between the side nets 11a of the cage main body 11.
In this example, the restraint wire 14 connects the two facing side nets 11a.
Specifically, the two restraint wires 14 are arranged in a cross shape in a plan view along the lid surface panel 12c of the inner cage 12, and the side nets 11a facing each other are connected to each other.
By mutually restraining the side nets 11a on the four surfaces with the restraint wire 14, it is possible to prevent the side nets 11a from being confined due to the filling of the filling material 20.
In this example, as the restraint wire material 14, an IR-coated plated steel wire having hook-shaped portions that hook into the mesh of the side net 11a is adopted at both ends.
However, the restraint wire 14 is not limited to this, and may be, for example, a fiber rope, a wire rope, or the like. In short, the material may be made of a material having predetermined strength and weather resistance, and may be configured to be reinforced by restraining the space between the side nets 11a.

<3> Filling material.
The filling material 20 is a lumpy or granular member to be filled in the futon basket 10.
The filling material 20 is composed of a combination of a coarse-grained material 21 and a fine-grained material 22 having a smaller particle size than the coarse-grained material 21.
Here, "small particle size" means that the coarse-grained material 21 and the fine-grained material 22 have their respective particle size ranges, and at least the lower limit of the particle size range of the fine-grained material 22 is the particle size range of the coarse-grained material 21. It means that it is smaller than the lower limit.

<3.1> Coarse grain material.
The coarse-grained material 21 is a filling material that fills the lid surface panel 12c in the basket body 11.
In this example, split chestnut stone having a particle size of 200 mm is used as the coarse grain material 21.
The particle size of the coarse-grained material 21 is not limited to this, and may be larger than that of the fine-grained material 22 and within the particle size range larger than the mesh size of the wire mesh of the cage body 11, but the particle size is in the range of 100 mm to 300 mm. It is more preferable to have it in.
The type of coarse-grained material 21 is not limited to split crushed stone, and may be single-grain crushed stone, rock crushed stone, recycled crushed stone such as concrete lump or brick lump.
The coating layer Lb is formed by the coarse-grained material 21 filled in the cage body 11.
Since the coating layer Lb can secure large voids in the coarse-grained material 21 by the coarse-grained material 21 having a large particle size, the wave energy in water is sequentially dispersed and absorbed among the coarse-grained materials 21 to absorb the surrounding waves. It can be reduced to a level that does not cause scouring.

<3.2> Fine grain material.
The fine-grained material 22 is a filling material 20 to be filled in the inner basket 12.
In this example, crushed stone having a particle size of 50 mm is used as the fine-grained material 22.
The particle size of the fine-grained material 22 is not limited to this, and may be smaller than that of the coarse-grained material 21 and within the particle size range larger than the mesh size of the geogrid of the inner cage 12, but the particle size is 20 mm to 100 mm. It is more preferable to be in the range.
This is irrational in terms of the cost and strength of the net material to be captured when the grain size is smaller than 20 mm, and when the grain size is coarser than 100 mm, the meshing force between the fine grain materials 22 becomes stronger and manual packing work is required instead of heavy machinery. This is because
Further, the type of the fine-grained material 22 is not limited to crushed stone, and may be cracked stone, boulder, recycled crushed stone, or the like.
The fine-grained material 22 filled in the inner basket 12 constitutes the suction prevention layer La.
When the sand under the bottom net 11b is sucked from the seabed by the water flow, the suction prevention layer La discharges only water and traps the sand in the small gaps of the fine-grained material 22 to capture the sand. It is possible to prevent suction.

<4> Method of manufacturing a scouring prevention structure.
The scouring prevention structure 1 of the present invention is manufactured by, for example, the following procedure.
The basket main body 11 is composed of four points: a main body portion in which two side nets 11a are deployably connected to both sides of the bottom net 11b in the width direction, the remaining two side nets 11a, and a lid net 11c. To.
The bottom panel 12b of the inner cage 12 is attached to the bottom net 11b. Use a C-ring or wire for mounting. Similarly, the side panel 12a is attached to the lower part of each side net 11a.
The two side nets 11a of the main body are erected and assembled in a U-shape in cross section, and the other two side nets 11a are connected by the connecting member 13.
As a result, the inner basket 12 without the lid surface panel 12c is formed in the cage main body 11 without the lid surface net 11c.
The inside of the inner basket 12 is filled with the fine-grained material 22. In this example, since the fine-grained material 22 is crushed stone having a particle size of 100 mm or less, it can be filled using a heavy machine. For this reason, workability is high as compared with the conventional technique in which all the filling materials are processed.
After filling the fine-grained material 22, the upper part of the four side panel 12a is covered with the lid panel 12c and fixed with a C ring or the like.
Two restraint wires 14 are arranged in a cross shape in a plan view in the cage main body 11, and the side nets 11a facing each other are connected to each other.
The coarse-grained material 21 is placed on the lid surface panel 12c.
After filling the coarse-grained material 21, the upper part of the four side surface nets 11a is covered with the lid surface net 11c and connected with the connecting material 13.

<5> Functions of suction prevention layer and coating layer.
If the scouring prevention structure 1 is composed of only the suction prevention layer, the fine grain material 22 having a small particle size can capture the suction of sand, but the porosity of the fine grain material 22 is small, so that the wave power is sufficient. It cannot be dispersed and reduced, and a vortex may be generated around the bottom surface to cause scouring.
Further, when the scouring prevention structure 1 is composed of only the coating layer, the effect of dispersing wave power is excellent, but the difference between the particle size of the sand on the bottom of the water and the particle size of the coarse grain material 21 is large, so that the coarse grain material There is a risk that sand on the bottom of the water will be sucked out through the voids of 21.
On the other hand, the scouring prevention structure 1 of the present invention has a structure in which the particle size of the filling material 20 is gradually increased from the bottom surface by the combination of the suction prevention layer La and the coating layer Lb. It is possible to prevent the suction of sand from directly under the structure 1 and the scouring around the scouring prevention structure 1 at the same time.
Further, by using the covering layer Lb having a high porosity as a habitat for fish and shellfish, it is possible to exert a fishing reef function (Fig. 3).

1 Anti-scouring structure 10 Duvet cage 11 Basket body 11a Side net 11b Bottom net 11c Lid net 12 Inner basket 12a Side panel 12b Bottom panel 12c Lid panel 13 Connecting material 14 Restraint wire 20 Filling material 21 Coarse grain material 22 Fine-grained material La coating layer Lb suction prevention layer

Claims (6)

It is a scouring prevention structure that is made by filling the futon basket with a filling material.
The futon basket includes a basket body and an inner basket configured inside the basket body.
The cage body is composed of a bottom net, four side nets, and a lid net.
The inner basket includes a bottom panel attached to the inner surface of the bottom net, four side panels attached to the lower part of the inner surface of the four side nets, and a lid surface covering the upper part of the four side panels. Consists of a panel
The mesh size of the inner basket is smaller than the mesh size of the cage body.
The filling material is composed of a coarse-grained material and a fine-grained material having a smaller particle size than the coarse-grained material.
The suction prevention layer is formed by the fine-grained material filled in the inner basket.
A coating layer covering the suction prevention layer is formed of the coarse-grained material filled on the lid surface panel in the cage body.
Scour prevention structure. The scouring prevention structure according to claim 1, wherein the inner basket is made of a grid-like resin geogrid. The scouring prevention according to claim 1 or 2, wherein the coarse-grained material has a particle size in the range of 100 mm to 300 mm, and the fine-grained material has a particle size in the range of 20 mm to 100 mm. Structure. The aspect according to any one of claims 1 to 3, wherein the bottom surface net, the side surface net, and the lid surface net are wire mesh panels formed by extending a diamond-shaped wire mesh inside a frame body. Scavenging prevention structure. The scouring prevention structure according to claim 4, wherein the diamond-shaped wire mesh is made of a wire rod obtained by coating a zinc-aluminum alloy-plated steel wire with a resin. The scouring prevention structure according to any one of claims 1 to 5, further comprising a restraint wire rod connecting the two facing side nets.

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