Embankment erosion control structure and method for constructing the structure

Abstract

To provide an erosion-suppressed structure of a dam body capable of suppressing and preventing erosion of a dike rear slope face in a case of overflow and suction of rear face ground of concrete block for slope toe protection, meeting the demand for the invention of "tenacious dike" hardly broken in overflow and capable of delaying the time of breakage as much as possible.SOLUTION: In the present invention, a flat granular laying object 3 is laid on a downward inclined dam body rear slope face 2, in a prescribed thickness to form a first laying layer 4 on a shallow layer part of the dam body rear slope face, and to form a second laying layer 6 serving as a surface soil layer by laying the surface layer on an upper layer of the first laying layer 4. The first laying layer 4 is laid and formed so that the flat face laying direction of the flat granular laying object 3 is horizontal and / or is in parallel to the downward inclined dam body rear slope face 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an embankment erosion control structure that controls and prevents gully erosion of embankments not only in river embankments but also in reservoir embankments and embankments for railways and roads, and a method for constructing such a structure. [Background technology]

[0002] In recent years, along with an increase in short-term heavy rains due to climate change, the collapse of river levees in particular has been on the rise. Recently, levee collapses, caused in part by overflow, occurred in the Kinu River during the Kanto and Tohoku heavy rains, and in the Tokoro River during the Hokkaido heavy rains.

[0003] In recent typhoons, for example, it has been reported that 86% of the 140 levee collapses that occurred on national and prefectural rivers were caused by overtopping. It is expected that flood disasters due to climate change will become more frequent and severe in the future, and there is an even greater need for "resilient levees" that are less likely to collapse even if overtopped and can delay the time until collapse as much as possible. To achieve this, it is necessary to suppress and prevent the erosion of the back slope of the levee when overtopping occurs, and the suction of the ground behind the concrete blocks used to protect the toe of the slope.

[0004] Furthermore, issues such as erosion of the back slope of river levees when water overflows are considered to be similar to issues related to the suppression and prevention of erosion in reservoir levees, railway embankments, and road embankments. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-61466 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was devised to solve the above-mentioned problems in the past, and in response to the demand for the invention of a "resilient levee" that is less likely to collapse even if overflowed and that can delay the time until it collapses as much as possible, it has as its object to provide an erosion-control structure for a levee that can control and prevent erosion of the back slope of the levee when overflowing and the suction of the ground behind the concrete blocks used to protect the toe of the slope, and to provide a method for constructing such a structure.

[0007] In areas surrounded by the sea, such as Japan, there is a huge catch of shellfish such as scallops and oysters. However, after harvesting the meat of scallops, oysters, and other shellfish, a large amount of shells remain, and there has long been a demand for methods to utilize these shells. For example, large amounts of scallop and oyster shells are piled up in coastal areas, causing environmental problems such as bad odors and poor scenery. In order to solve these problems, efforts have been made to use scallop and oyster shells as construction materials, but the amount that can be used is still limited. Therefore, finding new ways to utilize scallop shells in large quantities will broadly lead to the conservation and development of the marine environment, as well as contributing to a circular society and the SDGs.

[0008] It has also been reported that crushed scallop shells have a relatively high shear strength. Furthermore, the flattened crushed shells are less susceptible to the pressure of flowing water, and the frictional resistance between the crushed shells is also high. Therefore, laying a layer of crushed shells on the shallow part of the rear slope of the embankment will have the effect of suppressing erosion caused by overflow and suction of the ground behind the protective block.

[0009] In this way, the present invention also has the objective of contributing to the "conservation and development of the marine environment," as well as to a circular society and the SDGs. [Means for solving the problem]

[0010] The present invention relates to A flat particle size shaped material is laid to a predetermined thickness on a downwardly sloping rear slope of the embankment to form a first layer in a shallow portion of the rear slope of the embankment, and topsoil is laid on top of the first layer to form a second layer which serves as a topsoil layer; The first laying layer is formed by stacking the flat particle size shaped laying material so that the flat surface arrangement direction is horizontal and / or parallel to the downward slope of the bank back slope. It is characterized by: or A flat particle size shaped material is laid to a predetermined thickness on the downward sloping rear slope of the embankment to form a first layer in the shallow part of the rear slope of the embankment, and topsoil is laid on top of the first layer to form a second layer which will be a topsoil layer. The first layer is formed by stacking the flat particle size shaped material so that the flat surface arrangement direction is horizontal and / or parallel to the downward sloping rear slope of the embankment, and an intermediate layer integrated with the roots of plants is formed between the first and second layers on the surface side of the first layer. It is characterized by: or The thickness of the flat particle size shaped laying material is 0.3 mm to 3 mm; It is characterized by: or The particle size of the flat particle size shaped laying material is 0.7 mm to 100 mm; It is characterized by: or The flat particle size shaped laying material is formed by crushing shells, It is characterized by: or The flat particle size shaped laying material formed by crushing the shells has an internal friction angle of 35° or more. It is characterized by: or The shells are scallop, oyster shells, etc. It is characterized by: or The flat particle size shaped construction material is laid on the downward slope of the back slope of the embankment so that the flat surfaces overlap each other to form a first laying layer, and then a second laying layer comprising soil is laid on the surface of the first laying layer, The first laying layer is formed by stacking so that the flat surface arrangement direction of the flat particle size shaped laying object is horizontal and / or parallel to the downward slope of the bank back slope. It is characterized by: or The flat particle size shaped materials are laid on the downward slope of the back slope of the embankment so that the flat surfaces overlap each other to form a first layer, and then soil mixed with plant seeds or soil with not only seeds but also plants such as grass is laid on the surface of the first layer to form a second layer. The roots of the plants in the second laying layer extend in the direction of gravity until they reach near the surface of the first laying layer, and then extend laterally along the surface of the first laying layer, and the vegetated roots and the soil near the surface of the first laying layer are integrated to form an intermediate laying layer. It is characterized by: or The seed of the plant is a seed of a plant belonging to a stolon or a runner. It is characterized by the above. Effect of the Invention

[0011] According to the present invention, it is possible to construct a "resilient levee" or "resilient embankment" that is unlikely to collapse even if overflowing and that can delay the time until collapse as much as possible, thereby achieving the excellent effect of suppressing and preventing erosion of the back slope of the levee or embankment when overflowing, and suppressing and preventing the suction of the ground behind the concrete blocks used to protect the toe of the slope. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of the present invention. [Diagram 2]FIG. 1 is an explanatory diagram (1) for explaining the formation of a first laying layer. [Diagram 3] FIG. 2 is an explanatory diagram (2) for explaining the formation of the first laying layer. [Figure 4] FIG. 13 is an explanatory diagram illustrating the formation of the second laying layer and the intermediate laying layer. [Diagram 5] FIG. 1 is an explanatory diagram illustrating an overflow experiment of a first laying layer made of crushed shells. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will now be described with reference to the embodiments shown in the drawings. Fig. 1 shows an embodiment of the present invention, in which the present invention is applied to a levee. That is, this is an example in which the present invention is applied to the back slope 2 of a levee. In the present invention, a large amount of flat particle size shaped materials 3 are produced, arranged so that the top and bottom surfaces face the stacking direction, and stacked. The flat particle size shaped materials 3 can be produced from a large amount of remaining shells. For example, they are produced from remaining shells of scallops.

[0014] In recent years, the shells that remain after the meat has been removed from large amounts of edible shellfish such as scallops have been piled up in coastal areas, causing environmental problems such as foul odors and poor scenery. In order to solve this problem, efforts have been made to use the remaining shells, such as scallop shells, as construction materials, but the amount that can be used is still limited. Therefore, finding new ways to utilize large quantities of scallop and other shells has become an extremely important task.

[0015] These large amounts of shells are crushed, for example, by trampling them with heavy machinery, to generate a large amount of flat particle size-shaped installation material 3. The crushed shells can then be sorted into predetermined particle sizes using a sieve or the like. However, they can also be used without being sorted into predetermined particle sizes.

[0016] For example, it is possible to divide the material 3 into flat particle size shaped materials 3 with a particle size of 0.85 to 2.0 mm, then flat particle size shaped materials 3 with a particle size of 2.0 to 4.75 mm, then flat particle size shaped materials 3 with a particle size of 9.5 to 19.0 mm, and finally flat particle size shaped materials 3 with a particle size of up to 100 mm.

[0017] Then, flat particle size shaped materials 3 produced from the shells and sorted into respective particle sizes are layered and laid on the shallow layer of the back slope 2 of the embankment 1, with the top and bottom surfaces of the flat particle size shaped materials 3 facing in the layering direction as described above, to form a first layer 4.

[0018] In the present invention, flat particle-shaped material 3 is produced from shells. Shells are a material that is neither too thin nor too thick (thickness is about t=0.3-3mm) and has a high surface friction force (internal friction angle of crushed shells is large at φ≧35°), making them suitable for laying in layers on the shallow part of the back slope 2 to form the first laying layer 4. It is acceptable to use crushed pieces of artificial objects such as glass and ceramics when generating the flat particle size shaped installation 3. However, it is preferable to use a material that is not too thin or too thick (thickness t=about 0.3 to 3 mm) and has a large surface friction force (internal friction angle φ≧35°).

[0019] The lamination formation of the first laying layer 4 may be exemplified by the lamination formation example shown in FIG. That is, the flat particle size shaped material 3 is laid in close contact with the surface side of the back slope 2 of the embankment 1, and the flat particle size shaped material 3 is laid in layers with its upper and lower surfaces facing horizontally to form a laminated layer 5. The surface of the laminated layer 5 formed to a predetermined thickness is then compacted with a blade of a backhoe or the like. Next, the next laminated layer 5 is formed on top of the flat particle size shaped material 3 in a predetermined thickness, and stacked. The surfaces of the laminated layers 5 stacked in sequence are also compacted with a blade of a backhoe or the like. In this way, laminated layers 5 of predetermined thickness are formed in sequence, and these laminated layers 5 are stacked and stacked up to the top of the embankment 1.

[0020] Here, one side end of the multiple laminated layers 5 laid down in layers becomes stepped. Therefore, it is necessary to layer this to make it into a slope similar to the slope of the back slope 2. This is because the first laid layer 4 having a slope similar to the slope of the back slope 2 must be formed in the shallow part of the back slope 2.

[0021] In this case, it is considered preferable that the stacking direction of the flat particle size shaped material 3 laid near the surface side of the first laying layer 4 is parallel to the inclined surface of the back slope 2 (see Figure 3).

[0022] Incidentally, the large amount of flat particle-shaped materials 3 used to produce the laminate layer 5 are initially laid so that their upper and lower flat surfaces are horizontal, i.e., so that the upper and lower flat surfaces of the flat particle-shaped materials 3 face the stacking direction. This is because even if water overflows the back slope 2 of the embankment 1, it is possible to prevent the collapse of the first laying layer 4 on the back slope 2 against the flow of the overflowing water.

[0023] However, one side end of the multiple stepped laminate layers 5 needs to be layered to create a slope similar to the slope of the back slope 2, and at that time, the orientation of the upper and lower flat surfaces of the flat particle size shaped installation material 3 in the laminate layer 5 can be changed so that it is stacked to have a slope similar to the slope of the back slope 2.

[0024] In other words, it is preferable to form layers by changing the direction from a horizontally layered state to a direction parallel to the inclination of the back slope 2. This has the advantage that it is possible to more effectively prevent the intrusion of large amounts of vegetation roots into the first layer 4, which will be described later.

[0025] In this case, the first laying layer 4 is formed by forming a layer on the back side in which the flat surface of the flat particle size shaped material 3 faces the stacking direction, and forming a layer on the front side in which the orientation of the flat particle size shaped material 3's upper and lower flat surfaces is changed so that the material 3 is stacked to have a slope similar to that of the back slope 2, and these two layers form the first laying layer 4.

[0026] The first layer 4 can also be formed by laying all the flat particle size shaped materials 3 in layers parallel to the slope of the back slope 2. In this case, geocells, for example, are used. When the flat particle size shaped materials 3 are laid in layers parallel to the slope of the back slope 2, even if water overflows the back slope 2, resistance to the overflow is small because all the flat particle size shaped materials 3 are laid in layers in the same direction as the flow of the overflow water, and therefore the collapse of the first layer 4 can be prevented.

[0027] The choice of which of the above-mentioned layered laying methods to adopt may be determined by assessing the situation, such as the stability of the embankment 1 at the site and the type of overflow condition of the overflow water that will occur.

[0028] As described above, the first layer 4 is formed in the shallow portion of the back slope 2 by laying layers of a predetermined thickness on the back slope 2 of the embankment 1 having a downward slope, and then topsoil is laid on top of the first layer 4 to form the second layer 6, which will serve as the topsoil layer.

[0029] The second laid layer 6 may be formed, for example, by using a sprayer to spray soil onto the first laid layer 4 to a predetermined thickness. After spraying, the soil is compacted to form the second laid layer 6.

[0030] The second layer 6 is formed, for example, by spreading soil to a predetermined thickness on the first layer 4, and then compacting it with the blade of a backhoe, in the same manner as the crushed shell layer, which is the first layer 4. After that, soil mixed with plant seeds is sprayed to a predetermined thickness on the compacted soil using a sprayer, thereby completing the second layer 6.

[0031] In addition, when forming the final finish of the second laying layer 6, it is not only possible to use soil mixed with plant seeds, but it is also possible to apply soil that has already been grown with plants such as grass to form the final finish of the second laying layer 6.

[0032] As mentioned above, if the second laying layer 6, which is a relatively fine-grained soil layer, is laid as a covering soil on top of the crushed shell layer that will become the first laying layer 4, it is expected that the capillary barrier ground will constantly function to suppress rainfall infiltration into the inside of the levee 1, and will also keep the inside of the levee in an unsaturated state.

[0033] In addition, since the crushed shell layer, which is the first layer 4, is used to stack materials with flat particle size, it has the advantage that the covering soil material is less likely to be mixed in even without the use of a covering soil contamination prevention sheet, etc., and it is expected that the capillary barrier effect will be further maintained.

[0034] As described above, in the present invention, when forming the second laying layer 6, for example, seeds of plants 8 such as grass or Mizuna are mixed with the soil to be sprayed and sprayed, or soil on which plants such as grass have already been grown is applied to provide the final finish to the second laying layer 6. The seeds of the plants 8 or the plants already grown in the soil are considered to be those belonging to the stolon or runner.

[0035] In other words, it is preferable that the plant 8 has a stem that grows horizontally near the ground, or that the stem that emerges from the parent plant grows long and creeps horizontally along the ground surface, and buds and roots develop from the nodes at the tip to become offshoots. Seeds of plants that have stolons or runners, such as grass, germinate in the second laying layer 6, which is made of soil.

[0036] The sprouted roots, or the roots of plants already planted in the soil, grow in the direction of gravity until they reach the surface of the first laying layer 4, and then spread out horizontally, crawling along the surface of the first laying layer 4. Alternatively, the stems that emerge from the parent plant grow long and close to each other, crawling horizontally along the ground surface, and buds and roots develop from the nodes at the tips, producing offshoots.

[0037] In this way, the roots grow in the direction of gravity until they reach near the surface of the first laying layer 4, and then they grow laterally along the surface of the first laying layer 4, and the vegetated roots and the soil near the surface of the first laying layer 4 are integrated, and the integrated layer forms a strong intermediate laying layer 7. The formation of this intermediate laying layer 7 suppresses erosion of the back slope 2 of the embankment 1 by overflow water, and extends the time until it collapses.

[0038] In other words, the roots of the vegetation grow within the second laying layer 6, and then at the layer boundary surface between the second laying layer 6, which is the topsoil layer, and the first laying layer 4, which is the crushed shell layer, an intermediate laying layer 7 is formed as an integrated layer that grows parallel to the layer boundary surface, and the intermediate laying layer 7 and the first laying layer 4, which is the crushed shell layer, form a strong composite layer, thereby suppressing and preventing erosion of the back slope 2 of the embankment 1 due to overflowing water (see Figure 4).

[0039] In the present invention, an indoor experiment was conducted using a small soil tank in order to confirm the effect of natural materials (shells) in suppressing erosion of the rear slope of the embankment and suction from the rear surface of the protective block.

[0040] As a result, it became clear that laying a layer of crushed shells on the shallow layer of the rear slope of the embankment or on the back surface of the protective blocks was effective in suppressing erosion and suction caused by overtopping. The experimental results are shown in Figure 5. As shown in Figure 5, it became clear that laying a layer of crushed shells on the shallow layer of the rear slope of the embankment or on the back surface of the protective block was effective in suppressing erosion and suction caused by overtopping.

[0041] (Experimental Results) Results on erosion resistance to overtopping (stability of embankment) Figure 5 shows the difference in erosion of the rear slope of the embankment and deformation of the embankment over time due to overtopping. In Case 1, seepage progressed from the top of the embankment through the crushed shell layer almost directly below, and the seepage water carried sand particles, causing the collapse of half of the embankment. Next, when the shell particle size was 0.85 to 2.0 mm (Case 2), the crushed shell particles were gradually washed away from the surface by the surface runoff water, leading to the fragmentation and movement of the crushed shell layer, and the crushed shells were deposited at the foot of the embankment reinforced with wire mesh. During the movement of the crushed shell layer, sand particles in the shallow layer of the rear slope of the embankment flowed out from the fragmented part of the crushed shell layer to the foot of the embankment, and the embankment erosion progressed. Note that the gaps in the crushed shell layer were small, so the outflow of sand particles through the gaps in the crushed shell layer was suppressed. After that, the movement of the crushed shell layer and the outflow of sand particles from the fragmented part of the crushed shell layer ended, and the erosion weakened. In addition, in the case of shell sizes of 2.0 to 4.75 mm (Case 3), as in Case 2, even if the seepage water below the crushed shell layer carried sand particles, the outflow of sand particles through the gaps in the crushed shell layer was suppressed, so the shape of the dam was maintained even after 180 seconds. Furthermore, in the case of shell sizes of 9.5 to 19.0 mm (Case 4), the overflow water passed almost directly below the crushed shell layer from the crest end and infiltrated. In Case 4, the gaps in the crushed shell layer were large, and sand particles flowed out through the gaps in the crushed shell layer together with the seepage water, so the dam erosion progressed. In addition, in Case 4, the crushed shell layer did not deform with the erosion of the dam body, and the cavity between the crushed shell layer and the dam body was noticeably expanding, but at around 180 seconds, the crushed shell layer collapsed and the cavity disappeared. Case 4 showed similar behavior to Case 1, but the amount of erosion at the same time was smaller in Case 4.

[0042] (Consideration) When comparing Case 1 without countermeasures with the other cases with countermeasures using the crushed shell layer, a significant difference was observed in the suppression of the outflow of sand particles from the shallow layer of the back slope (suppression of erosion of the embankment body), indicating the possibility of an effect of suppressing the erosion of the crushed shell layer. In addition, when comparing Cases 2 to 4 with different shell particle sizes among the countermeasures, the crushed shell layer itself was eroded and divided by the surface runoff water in Case 2, where the shell particle size was small. Furthermore, in Case 4, where the shell particle size was large, the overflow water passed almost directly below the crushed shell layer from the top end of the embankment body and infiltrated into the embankment body ground, showing a similar infiltration behavior to Case 1 without countermeasures. In addition, in this experiment, in Case 3, where the shell particle size was intermediate, the dispersion of the infiltration of the overflow water into the shallow layer of the back slope of the embankment was confirmed. Due to the above differences in the infiltration method, the amount of erosion of the embankment body also differed. From this, it was confirmed that changing the particle size of the crushed shell layer produced significantly affects the infiltration behavior into the shallow ground on the rear slope of the embankment, as well as the erosion resistance of the shallow ground and the deformation behavior of the embankment over time. From the above, it became clear that while it is best to prevent the embankment from collapsing, it is necessary and important to use crushed shells of an appropriate particle size in order to at least achieve the effect of extending the time until the embankment collapses, from the perspective of feasibility, etc.

[0043] (summary) A small soil tank overflow experiment was conducted, and the following findings were obtained regarding the erosion resistance of the crushed shell layer at the shallow layer on the back slope of the embankment and the deformation behavior (stability) of the embankment body. 1) When comparing a case where no crushed shell layer was laid with a case where the crushed shell layer was laid, it was found that in some cases the location where the overflow water seeps into the shallow ground on the back slope of the levee can be shifted and dispersed further downstream. 2) When comparing the case where no crushed shell layer was laid with the case where the crushed shell layer was laid, the case where the crushed shell layer was laid was able to prevent the outflow of silica sand No. 6 particles and also suppress the amount of erosion of the embankment. 3) When the shell particle size was changed, the way in which the shells penetrated into the shallow layer of the back slope of the embankment also changed, and this could be roughly divided into three patterns according to the particle size. 4) The manner in which the embankment erosion occurred varied depending on the shell size, and crushed shells with a particle size of 2.0 to 4.75 mm were particularly effective in preventing embankment erosion. 5) Given the experimental conditions used in this study, it was found that crushed shells with a particle size of 2.0 to 4.75 mm were the most suitable for extending the time until rupture, as they dispersed seepage and suppressed erosion.

[0044] As described above, laying a layer of crushed shells on the shallow layer of the rear slope of the levee is a levee strengthening measure that can be applied relatively easily to existing levees, and we have demonstrated the feasibility of CB overtopping-resistant levee that is excellent in terms of maintenance, environment, economy, and earthquake resistance.

[0045] The above experimental results are for a crushed shell layer. As described above, if an intermediate laying layer 7 is formed on top of the crushed shell layer by combining the roots of vegetation with the soil, the back slope 2 of the embankment 1 can be further strengthened. [Industrial Applicability]

[0046] As described above, the present invention is applicable not only to river embankments, but also to the prevention of gully erosion in general reservoir embankments, railway and road embankments, etc. [Explanation of symbols]

[0047] 1. Embankment 2 Back slope 3 Flat grain size laying material 4 1st installation object 5 Laminate layer 6 Second laying layer 7 Intermediate layer 8 plants

Claims

1. A flat particle size shaped material is laid to a predetermined thickness on a downwardly sloping rear surface of the embankment to form a first laying layer in a shallow layer on the rear surface of the embankment, and topsoil is laid on top of the first laying layer to form a second laying layer which serves as a topsoil layer; The first laying layer is formed by stacking the flat particle size shaped laying material so that the flat surface arrangement direction is horizontal and / or parallel to the downward slope of the bank back slope. A bank erosion control structure characterized by the above.

2. A first layer is formed in the shallow part of the rear slope of the embankment by laying flat particle size shaped materials to a predetermined thickness on the downward sloping rear slope of the embankment, and a second layer is formed as a topsoil layer by laying topsoil on top of the first layer, and the first layer is formed by stacking the flat particle size shaped materials so that the flat surface arrangement direction is horizontal and / or parallel to the downward sloping rear slope of the embankment, and an intermediate layer integrated with the roots of plants is formed between the first layer and the second layer on the surface side of the first layer. A bank erosion control structure characterized by the above.

3. The thickness of the flat particle size shaped laying material is 0.3 mm to 3 mm; 3. The embankment erosion control structure according to claim 1 or 2.

4. The particle size of the flat particle size shaped laying material is 0.7 mm to 100 mm; 4. The embankment erosion control structure according to claim 1, 2 or 3.

5. The flat particle size shaped laying material is formed by crushing shells, 5. The embankment erosion suppression structure according to claim 1, 2, 3 or 4.

6. The flat particle size shaped laying material formed by crushing the shells has an internal friction angle of 35° or more.

6. The embankment erosion control structure according to claim 5.

7. The shells are scallop or oyster shells.

7. The embankment erosion control structure according to claim 6.

8. The flat particle size shaped construction material is laid on the downward slope of the rear slope of the embankment so that the flat surfaces of the construction material overlap each other to form a first laying layer, and then a second laying layer comprising soil is laid on the surface of the first laying layer, The first laying layer is formed by stacking the flat particle size shaped laying objects so that the flat surface arrangement direction is horizontal and / or parallel to the downward slope of the bank back surface. A method for constructing an erosion control structure for a bank, comprising:

9. A first layer is formed by layering flat particle size shaped materials on the downward slope of the back slope of the embankment so that the flat surfaces of each material overlap each other, and then a second layer is formed by laying soil mixed with plant seeds or soil on which plants are grown on the surface of the first layer; The roots of the plants in the second laying layer extend in the direction of gravity until they reach the surface of the first laying layer, and then extend laterally along the surface of the first laying layer, and the roots and the soil near the surface of the first laying layer are integrated to form an intermediate laying layer. A method for constructing an erosion control structure for a bank, comprising:

10. The seed of the plant is a seed of a plant that belongs to a stolon or a runner. A method for constructing an erosion control structure for a bank according to claim 9.

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