JP2018100480A - Steel revetment shelf structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel revetment shelf structure having both advantages of excellent landscaping property of a natural stone revetment construction method and of capability of exerting a river bank protective function against strong flowing water like flooding in a stone-filled cage revetment construction method.SOLUTION: In the steel revetment shelf structure 14, partition surface parts 7 are formed by setting partitioning screen materials 6 in side frames 5 structured with front side erected column materials 1, rear side erected column materials 2 and upper and lower beam materials 3, 4 connecting upper ends and lower ends of the column materials 1, 2 respectively, and the multiple partition surface parts 7 are arranged in the flow direction of a river in the revetment position with spaces. Between the adjacent partition surface parts 7, 7, bottom face screen materials 8 are arranged between the lower beam materials 4, 4 to form bottom face parts 9, back face screen materials 10 are arranged between the rear side column materials 2, 2 to form back face parts 11, and filling materials 13 like gravel are filled in a steel revetment shelf 12 with a front face part and an upper face part opened to form the steel revetment shelf structure.SELECTED DRAWING: Figure 1

Description

  The present invention belongs to the technical field of a steel revetment structure that is assembled at a local revetment position and packed as a revetment structure by packing a filling material such as stones and gravel. The present invention relates to a steel revetment shelf structure that is opened (opened) to form a shelf.

  For river and riverbank revetments, in consideration of environmental friendliness, instead of conventional concrete blocks, a natural stone revetment construction method that builds a revetment with only stone gravel, a futon basket filled with stones, and a basket mat A stone-sealed basket revetment method called “Empty” is being implemented.

The natural stone revetment construction method is inexpensive and has excellent scenic characteristics because it builds a revetment only with stones and gravel, so it has been re-examined as a multi-natural river construction method and has been actively researched in recent years.
In addition, the stone-clad cage revetment method is a representative of the creation of multi-natural rivers using stone gravel, in which a box body is formed with a wire net and the like, and the bank of the embankment is protected from the river water by filling stone gravel. In recent years, various variations have been developed (see, for example, Patent Documents 1 to 4).

Utility Model Registration No. 3032260 No. 05-34825 Japanese Patent Laid-Open No. 08-13446 Japanese Patent Laid-Open No. 10-1925

The natural stone revetment method resists the river water only by its own weight and the engagement of the adjacent stones, so that the stones will stay in place against large flowing water such as floods. In addition, there was a problem that the function as a revetment could not be achieved, such as surrounding stones and gravel being transported in a chain.
On the other hand, in the stone-clad cage revetment method, stones and gravel are restrained by a box made of wire mesh or the like, so that the river bank protection function can be exerted even against large flowing water such as floods. However, because the wire mesh is exposed on the revetment surface, it cannot be said that the scenery is good. In addition, there is a risk that the scenic performance will be significantly impaired by the accumulation and accumulation of dust and dead leaves on the wire mesh.

  The present invention has been devised in view of the problems of the background art described above, and the object of the present invention is to provide an advantage of the natural stone revetment method with excellent scenic properties and the stone-clad basket revetment method. It is to provide a steel revetment shelf structure that has both the advantages of being able to exert the river protection function against large running water such as floods.

  As a means for solving the above-mentioned problems, a steel revetment rack structure according to the invention described in claim 1 includes: a pillar material erected at the front part; a pillar material erected at the rear part; A plurality of partition surface portions, each having a partition screen material in a side frame composed of upper and lower beam members that connect the upper and lower ends of the column material, are spaced apart in the river flow direction at the revetment position. The bottom screen material is formed between the lower beam members and the bottom screen material is formed between the adjacent partition surface portions, and the back screen material is disposed between the rear column materials. It is characterized in that it is packed with a filling material such as stone gravel on a steel revetment shelf that is provided and has a rear surface portion and a front surface portion and an upper surface portion that are open.

  The invention described in claim 2 is the steel revetment shelf structure according to claim 1, wherein the steel revetment shelf includes a steel revetment shelf unit including the partition surface portion, a bottom surface portion, and a back surface portion. A plurality of them are continuously arranged in the flow direction, and are connected and integrated.

  According to a third aspect of the present invention, in the steel revetment shelf structure according to the first or second aspect, any one of the connecting portions between the lower beam material and the bottom surface screen material of the bottom surface portion is a river. By adopting a pin connection structure having a loose hole that is long in the flow direction, the bottom surface is configured to follow the curved portion of the revetment.

  According to a fourth aspect of the present invention, in the steel revetment shelf structure according to any one of the first to third aspects, at least the partition surface portion of the partition surface portion, the bottom surface portion, and the back surface portion is the inside packing. The screen structure is formed with a gap through which the material does not pass.

  The invention described in claim 5 is the steel revetment shelf structure according to any one of claims 1 to 4, wherein the screen material is a bar-shaped member such as a flat bar or an angle material. To do.

The steel revetment shelf structure according to the present invention is formed by packing a packing material such as gravel into the inside of a steel revetment shelf in which partition surfaces adjacent to each other on the left and right sides are connected by a bottom screen material and a back screen material. It has a simple structure with a small number of members and has the following effects.
(1) Most of the steel revetment shelves that form the skeleton are covered with filling material and are inconspicuous, so they follow the advantages of excellent scenic characteristics, such as the natural stone revetment construction method that builds a revetment using only stone gravel. be able to. Nevertheless, when a large flow of water, such as flooding, which is a drawback of the natural stone revetment method, occurs, the screen effect of the partition surface portion allows the flow of water to pass smoothly downstream and catches the movement of the filling material. Therefore, even if some of the filling material is transported, the chained filling material can be reliably prevented from being transported. The benefits of superior functionality can also be followed.
In summary, it has both the advantages that the natural stone revetment method has excellent scenic characteristics and the advantages of being able to demonstrate the river protection function against large running water such as flooding of the stone-clad cage revetment method. It is possible to realize a steel revetment shelf structure that is superior to the above.
(2) Exposed on the revetment surface is a padding material such as stone gravel, and there are no wire mesh or other constraining members, so the wire mesh that was the subject of the stone-clad basket revetment method is exposed on the revetment surface. Therefore, it is possible to solve the problem of losing scenery.
(3) Since the screen material for the bottom surface and the screen material for the back surface are each connected to the partition surface portion by the pin connection structure, deformation such as a substantially parallelogram can be allowed within a limit that allows the screen to rotate about the pin. Therefore, such a deformation effect makes it possible to arrange the steel revetment shelves in a flexible manner such as being able to follow well according to the curved shape and unequal subsidence shape of the revetment position, and has the advantage of facilitating on-site response. is there. When the bottom screen material is connected by a pin connection structure in which a long loose hole is formed in the flow direction (lateral direction) of the river, there is an advantage that it is possible to further facilitate on-site correspondence. Such a deformation effect leads to suppression of the number of members, and has an advantage of being excellent in economic efficiency.
(4) Since the steel revetment shelf has a substantially L-shaped configuration with a bottom surface and a back surface, the front surface and the top surface are opened in series, so There are no obstacles that obstruct the repair (replenishment) work, and the work can be repaired with the same simple and simple work as the natural stone revetment method. Therefore, it is possible to perform a repair work that is rational and excellent in workability and economy.
(5) Since the steel revetment rack structure (steel revetment rack) is constructed in a continuous and continuous structure in the river flow direction, it allows slight deformation over its entire length. However, the river bank protection effect can continue to be exerted permanently without impairing the function of the bank.

It is the perspective view which showed the state which installed the steel revetment shelf which comprises the steel revetment shelf structure concerning this invention in the revetment position. It is the perspective view which showed the steel revetment shelf structure formed by stuffing medium filling materials, such as stone gravel, in the steel revetment shelf which concerns on FIG. It is the perspective view which showed the state after big flowing water, such as a flood, generate | occur | produced about the steel revetment shelf structure which concerns on FIG. It is the perspective view which illustrated the state which installed the steel revetment shelf which concerns on FIG. 1 following the uneven settlement shape of the ground in a revetment position. It is the perspective view which illustrated the state which installed the steel revetment shelf which concerns on FIG. 1 following the curved shape of a revetment position. It is the perspective view which showed the state which installed the steel revetment shelf which concerns on FIG. 1 in step shape according to the form of the revetment position.

  Next, an embodiment of a steel revetment shelf structure according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1 and FIG. 2, the steel revetment rack structure 14 according to the present invention includes a pillar material 1 erected at the front part, a pillar material 2 erected at the rear part, and the front and rear parts. The partition surface portion 7 provided with the partition screen material 6 in the side frame 5 composed of the upper and lower beam members 3 and 4 that connect the upper and lower ends of the column members 1 and 2 of A plurality of plates are arranged at intervals in the flow direction, and between the adjacent partition surface portions 7 and 7, a bottom screen material 8 is disposed between the lower beam members 4 and 4 to form a bottom surface portion 9. The rear screen member 10 is disposed between the rear column members 2 and 2 to form the rear surface portion 11, and the steel revetment shelf 12 having a front surface portion and an upper surface portion are opened. This is carried out in a structure in which a filling material 13 such as is packed.

The steel revetment shelf structure 14 according to the illustrated example exemplifies a configuration in which three partition surface portions 7 are provided at predetermined intervals (for example, about 2 m) in the flow direction of the river. However, the minimum unit is two, and the number can be increased as appropriate according to the form (particularly the length) of the revetment to be installed.
Hereinafter, the structure of the said steel revetment shelf structure 14, especially the steel revetment shelf 12 is demonstrated.

The steel revetment shelf 12 includes a partition surface portion 7, a bottom surface portion 9, and a back surface portion 11.
(Partition surface 7)
The partition surface portion 7 is formed by integrating a partition screen material 6 in the frame of the side frame 5.
The side frame 5 is formed by assembling front and rear column members 1 and 2 and upper and lower beam members 3 and 4 in a frame shape.
As an example, the side frame 5 according to the present embodiment uses angle steel, which is an approximately T-shaped pair of two pillar members 1 and 2 at the front and rear parts, and the beam members 3 and 4 at the upper and lower parts. It is configured using CT section steel (T section steel). Specifically, the upper and lower beam members (CT sections) 3 and 4 are arranged so that the web portions face each other inward, and the web portions are arranged in front and rear column members (one set of two pieces). 1), 1 and 2 are sandwiched between each other, and the joints such as the joints are integrally joined together by means such as bolts, and the web part projects endlessly along the inner central line as a whole. It is configured in such a frame shape.

  Incidentally, the side frame 5 which concerns on a present Example is implemented by the trapezoid shape which inclined the upper end side of the pillar material 1 of the front part back (land side). This corresponds to an inclination angle (gradient) at which the filling materials 13 such as stone and gravel can be stacked well, and the inclination angle of the column material 1 can be appropriately changed according to the filling material 13 to be used. Yes, of course, it can also be carried out by standing in the direction of approximately 90 degrees (vertical).

  The partition screen material 6 uses a flat bar and is inclined at a required angle between the upper and lower beam members 3 and 4 and between the rear column member 2 and the lower beam member 4 in the side frame 5. By using the web portion protruding inward of the corresponding beam members 3, 4 or the column member 2, they are joined and joined by a joining means such as a bolt to form the partition surface portion 7. In addition, you may implement the said flat bar with the means arrange | positioned and joined substantially horizontally between the pillar materials 1 and 2 of the front-back part.

Here, when it illustrates about the magnitude | size of the member which comprises the said partition surface part 7, the pillar material 1 of the front part is L-50 * 50 * 6 (t), and is a pair of equilateral sides about 1120 (mm) in length. Implemented with Yamagata Steel. The rear column 2 is L-50 × 50 × 6 (t), and is implemented by a pair of equilateral angle irons having a length of about 1000 (mm). The upper beam member 3 is CT-100 × 200 × 8 × 12, and is made of CT steel having a length of about 1000 (mm). The lower beam member 4 is CT-100 × 200 × 8 × 12, and is implemented by CT section steel having a length of about 1500 (mm). The partition screen material 6 is FB-50 × 6 (t) between the upper and lower beam members 3 and 4 and is implemented by a flat bar having a length of about 1063 (mm). The distance between the beam members 4 is shorter than this, and the length is appropriate to keep the interval between the adjacent flat bars substantially constant. Incidentally, the interval (slit) between adjacent flat bars according to the present embodiment is maintained at about 125 mm, and is implemented with a screen structure in which a gap through which the filling material 13 does not pass is formed.
In addition, the said column materials 1 and 2 can also be implemented with steel pipes other than shape steel, such as angle steel. In addition to a flat bar, the screen material can be implemented by angle steel, or by means of extending expanded metal or a wire mesh in the plane of the side frame 5.

(About the bottom surface 9)
The bottom surface portion 9 is configured by arranging a bottom screen material 8 between adjacent lower beam members 4, 4.
In this embodiment, the bottom screen material 8 uses angle steel 8a and a flat bar 8b, and the angle steel 8a is disposed inwardly facing the front and rear ends of the lower beam members 4 and 4, respectively. A plurality of (six in the illustrated example) flat bars 8b are arranged substantially in parallel between the steels 8a, 8a with a required (for example, about 125 mm, which is the same as the partitioning surface portion 7), and the bottom screen. Both ends of the material (the angle steel 8a, the flat bar 8b) 8 are joined by a pin connection structure (for example, a bolt joint in this embodiment) by using the flange portion of the corresponding lower beam material (CT shape steel) 4. Thus, the bottom surface portion 9 is formed.
In addition, the said pin connection structure can be implemented by employ | adopting the combination of various metal fittings for connection other than a volt | bolt and a nut.

Thus, the screen material 8 for the bottom surface according to the present embodiment uses the angled steels 8a and 8a having high rigidity at the front and rear ends which are constituent elements of the frame portion forming the skeleton of the bottom surface portion 9, thereby As a result, the strength and rigidity of the bottom surface portion 9 are improved.
But the angle steel 8a arrange | positioned at the said rear-end part (land side) is a free state in which the bottom face part (horizontal part) and the lower beam materials 4 and 4 are not joined, The back part (vertical) Part) and the column members 2 and 2 at the rear part are devised to join with a pin connection structure (bolt joint in this embodiment). This is because only one of the bottom surface portion and the back surface portion is joined to the counterpart material (the beam material 4 or the rear column material 2), so that the entire bottom surface portion 9 of the steel revetment shelf 12 is used for the bottom surface. This is to allow deformation such as a substantially parallelogram when viewed in the plane direction within a limit that allows the screen material (mountain steel 8a, flat bar 8b) 8 to be pivoted using pins (bolts) that restrain both ends of the screen material. This deformation has the advantage that the steel revetment shelf 12 can be arranged in a flexible manner (such as the meandering shape of the river) in accordance with the curved shape of the revetment position (river meandering shape) and can be easily handled on site. There is.
Further, in this embodiment, the connecting portion (connecting portion) between the lower beam member 4 and the bottom screen member 8 is a pin connection in which either one is a loose hole long in the river flow direction (lateral direction). Has been implemented in the structure. By adopting a structure that can absorb so-called errors (avoids stress concentration on the local parts), the steel revetment shelf 12 can be tracked well in accordance with the curved shape of the revetment position. It becomes possible.
The significance of arranging the angle steel 8a at the front end (river side) of the bottom surface portion 9 according to this embodiment is that the padding material 13 such as stone gravel is effectively dammed and a good piled up state is reasonably achieved. This is because it has a shape and rigidity suitable for realization. In addition, the vertical portion of the angle steel 8a also has a significance of serving as a ruler (work shape management) for the flow direction of the river in installing the steel revetment shelf 12. By the way, when the flat bar 8b is arranged at the front end of the bottom part 9, the angle bar 8b is arranged if the flat bar 8b connecting the lower ends of the column members 1 and 1 is further arranged. The same effect (significance) can be demonstrated.

Incidentally, each of the two angle steels 8a constituting the bottom screen material 8 is, for example, L-65 × 65 × 6 (t) and an equal angle iron having a length of about 2000 (mm). Yes. Further, each of the five flat bars 8b is FB-50 × 6 (t) and is implemented with a length of about 2000 (mm). The space (slit) between the adjacent bottom screen materials 8 is maintained at about 125 mm, and the screen structure is formed with a gap through which the filling material 13 does not pass.
In addition, although the said screen material 8 for bottom faces which concerns on a present Example uses the angle steel 8a and the flat bar 8b together, it is not limited to this, All can also be implemented with the angle steel 8a, All It can also be implemented with a flat bar 8b. In addition, instead of the angle steel 8a or the flat bar 8b, an expanded metal or a wire mesh can be implemented by means of stretching in the plane of the bottom surface portion 9.

(About the back part 11)
The back surface portion 11 is configured by arranging a back screen material 10 between adjacent rear column members 2 and 2.
In the present embodiment, the back screen material 10 uses angle steels 10a and 8a and a flat bar 10b. In short, the angle steel 8 a located at the boundary between the back surface portion 11 and the bottom surface portion 9 is a constituent member of the bottom screen material 8 and a constituent member of the back screen material 10.
Based on the above, the back screen material 10 has angle steels 10a, 8a facing inwardly at the upper and lower ends of the rear column members 2, 2, and between the angle steels 10a, 8a, A plurality of (five in the illustrated example) flat bars 10b are arranged substantially in parallel with each other at a required interval (for example, about 125 mm which is the same as that of the partition surface portion 7 and the bottom surface portion 9). , 8a, flat bar 10b) both ends of 10 are joined by a pin connection structure (for example, bolt joint in this embodiment) using the flange portion of the corresponding rear column member (angle steel) 2, and thus the back portion 11 is formed.

As described above, the screen material 10 for the back surface according to the present embodiment uses the angled steel 10a and 8a having high rigidity at the upper and lower end portions which are constituent elements of the frame portion forming the skeleton of the back surface portion 11, thereby As a result, the strength and rigidity of the back surface portion 11 are improved.
The back surface portion 11 of the steel revetment shelf 12 restrains the back screen material 10 by implementing both end portions of the back screen material (angle-shaped steel 10a, 8a, flat bar 10b) 10 with a pin connection structure. As long as the pin (bolt) to be turned is a fulcrum, it can be deformed like a substantially parallelogram when viewed from the front. Therefore, it is possible to arrange the rear column member 2 in a vertical direction following the uneven settlement of the ground required for the steel revetment shelf 12, and the advantage of facilitating on-site correspondence is possible. is there. Further, there is an advantage that it is possible to prevent inconvenience that causes damage to the member due to stress concentration on the local area.

Incidentally, the angle steels 10a and 8a constituting the back screen material 10 are, for example, L-65 × 65 × 6 (t) and an equilateral angle steel having a length of about 2000 (mm). Further, each of the five flat bars 10b is FB-50 × 6 (t) and is implemented with a length of about 2000 (mm). An interval (slit) between the adjacent back screen materials 10 is maintained at about 125 mm, and a screen structure in which a gap through which the filling material 13 does not pass is formed.
In addition, although the said back screen material 10 which concerns on a present Example uses the angle steel 10a, 8a and the flat bar 10b together, it is not limited to this, All can also be implemented with the angle steel 10a, 8a. However, it is also possible to implement everything with the flat bar 10b. In addition, instead of the angle steels 10 a and 8 a or the flat bar 10 b, an expanded metal or a wire mesh can be implemented by means of stretching in the plane of the back surface portion 11.

  Thus, the steel revetment shelf 12 is formed by the partition surface portion 7, the bottom surface portion 9, and the back surface portion 11 having the above-described configurations, and the front surface portion and the top surface portion are opened. Such a structure, that is, a steel revetment shelf 12 having a substantially L-shaped configuration with a bottom surface portion 9 and a back surface portion 11 partitioned by adjacent partition surface portions 7 and 7 and having a front surface portion and a top surface portion opened in series. The steel revetment shelf structure 14 is constructed by stacking the filling material 13 such as stones or the like until reaching the same level as the upper beam material 3.

By the way, the steel revetment shelf structure 14 (steel revetment shelf 12) is often provided continuously over several tens of mails depending on the length of the revetment to be installed. In such a case, a steel revetment shelf unit having a length that can be transported by truck, including the partition surface portion 7, the bottom surface portion 9, and the back surface portion 11 so as to be able to cope with the field smoothly (for example, see FIG. 1). Are prepared in advance, arranged in the required number along the river flow direction at the site, and connected and integrated.
According to the steel revetment shelf 12 that can be deformed in a flexible manner with the above configuration, when the installation site is curved, the bottom surface portion 9 is deformed according to the curved shape and arranged in a stable state. In the case of unequal subsidence, the back surface portion 11 can be deformed according to the unequal subsidence shape and placed in a stable state without rattling (see, for example, FIG. 4). Therefore, it is possible to perform installation work with smooth on-site response and excellent workability.

In addition, when the bending deformation of the installation site is particularly large, it can be carried out in the form as shown in FIG. This is a trapezoidal frame portion that employs a shortened angle steel 8a at the front end portion of the bottom surface portion 9, and has the required rigidity with the angle steel 8a, 8a at the front and rear end portions and the lower beam members 4, 4. And one end portion of the flat bar 8b in the frame portion is free and laid under the central beam member 4. Even if it is such a form, the steel revetment shelf (unit) 12 stabilized by the dead weight effect | action of the filling material 13 stuffed after that, and by extension, the steel revetment shelf structure 14 can be implement | achieved.
By the way, the steel revetment rack 12 according to FIG. 1 is designed to continuously install different steel revetment shelves (units) on the partition surface portions 7 at both ends thereof, so that the upper and lower beam members 3, 4 are arranged. However, it is of course possible to use angle steel instead of CT steel.

Therefore, according to the steel revetment shelf structure 14 having the above-described structure, most of the steel revetment shelves 12 constituting the skeleton are covered with the filling material 13 such as stone gravel and are not conspicuous. It is possible to follow the advantages of excellent scenic characteristics like the natural stone revetment construction method. Nevertheless, when a large flow of water such as flood, which is a disadvantage of the natural stone revetment method, occurs, the screen effect of the partition surface portion 7 allows the flow of water to smoothly pass downstream while receiving the movement of the filling material 13 firmly. Therefore, even if a part of the filling material 13 is transported (see FIG. 3), the chained filling material 13 can be reliably prevented from being transported. The advantages of river bank protection such as revetment method can also be followed.
In summary, it has both the advantage that the natural stone revetment construction method is excellent in scenic beauty and the advantage that it can exert the river protection function against large running water such as flooding of the stone-clad cage revetment construction method,
A steel revetment shelf structure with excellent environmental performance can be realized.
Moreover, since the said steel revetment shelf 12 is the structure where the front part and the upper surface part were opened in series, there is no obstacle which obstructs the repair (replenishment) operation | work of the filling material 13 by the backhoe of a heavy machine. Therefore, it can be restored by a simple and simple operation similar to the natural stone revetment method.

Although the embodiments have been described with reference to the drawings, the present invention is not limited to the illustrated examples and includes a range of design changes and application variations that are usually made by those skilled in the art without departing from the technical idea thereof. I will mention that just in case.
For example, depending on the form of the installation site, as shown in FIG. 6, it is of course possible to provide the steel revetment shelf 12 in a step shape.

DESCRIPTION OF SYMBOLS 1 Front pillar material 2 Rear pillar material 3 Upper beam material 4 Lower beam material 5 Side frame 6 Partition screen material 7 Partition surface part 8 Bottom screen material 8a Angle steel 8b Flat bar 9 Bottom part 10 Back screen Material 10a Angle steel 10b Flat bar 11 Back surface 12 Steel revetment shelf 13 Filling material 14 Steel revetment shelf structure

Claims (5)

For partitioning in a side frame composed of a pillar material standing at the front, a pillar material standing at the rear, and upper and lower beam members connecting the upper and lower ends of the front and rear column materials. A plurality of partition surface portions provided with a screen material are arranged at intervals in the river flow direction at the revetment position, and a screen material for the bottom surface is disposed between the adjacent partition surface portions between the lower beam materials. And the bottom part is formed,
A back screen is arranged between the pillars at the rear to form the back, and the steel revetment shelves with the front and top open are packed with packing materials such as gravel. Steel revetment shelf structure characterized by comprising   The steel revetment shelf is formed by continuously connecting a plurality of steel revetment shelf units having the partition surface portion, the bottom surface portion, and the back surface portion in the flow direction of the river and connecting them together. The steel revetment shelf structure according to claim 1, characterized in that   The connecting portion between the lower beam member and the bottom screen member is a pin connecting structure in which either one is a loose hole long in the river flow direction, so that the bottom portion is a curved portion of the revetment. The steel revetment shelf structure according to claim 1 or 2, wherein the steel revetment shelf structure according to claim 1 or 2 is configured to be capable of following along the line.   4. The screen structure according to claim 1, wherein among the partition surface portion, the bottom surface portion, and the back surface portion, at least the partition surface portion has a screen structure in which a gap through which the filling material does not pass is formed. Steel revetment shelf structure described in 1.   The steel revetment shelf structure according to any one of claims 1 to 4, wherein the screen material is a bar-shaped member such as a flat bar or an angle material.

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