Levee slope reinforcement structure, levee slope reinforcement method, and block mat for levee slope reinforcement

Abstract

To provide an embankment slope reinforcement structure capable of more effectively preventing embankment breakage or extending the time until embankment breakage by attenuating the flow velocity of overflow water when overflowing, an embankment slope reinforcement method and a block mat for the embankment slope reinforcement.SOLUTION: In an embankment back slope reinforcement structure that protects an embankment land side slope against river overflow by laying a plurality of reinforcing blocks from an embankment back slope to the embankment back slope toe, the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the overflow and a second block provided on the downstream side of the first block. The first block has an inclined surface whose top surface is closer to the bottom surface on the upstream side than on the downstream side. The inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a dike slope reinforcement structure, a dike slope reinforcement method, and a block mat for dike slope reinforcement that suppress local scouring of a dike slope caused by overtopping water or river flow.

Background Art

[0002] In recent years, heavy rainfalls associated with abnormal weather have occurred in various places, causing large-scale floods and water disasters due to river flooding and dike breaches (overflow failures). Conventionally, as a river bank protection method, on the inner back slope of a dike, for example, the soil surface to be protected is leveled and compacted, a filter is laid, and then chestnut stones are stacked, and then concrete blocks are attached while applying cement mortar as joints on the upper surface.

[0003] However, in the case of the above structure, when water overflows the dike due to a large-scale water discharge, there are cases where the slope protection work is damaged and washed away. For example, as shown in FIG. 10, (1) the water flow breaks the dike due to the action of overtopping water or surge waves (coast), (2) the covering work on the back slope is washed away because the water flow becomes high-speed in the jet area of the back slope, (3) furthermore, the top protection work is washed away, and the embankment soil flows out from the gaps in the protection work, etc., which may lead to the collapse of the dike.

[0004] As a countermeasure, the height of the dike should be set to a height that does not overflow for any large-scale water discharge, but in reality, various problems such as land use problems, technical problems, and landscape problems often occur and it is often impossible. Therefore, in fact, dike strengthening methods have been tried in the direction of preventing the collapse of the dike as described above due to overtopping.

[0005] And, as a dike strengthening method, for example, a method of reinforcing the back bottom of the dike with blocks is known (see Patent Document 1 and Non-Patent Document 1). In this construction method, the back slope of the levee is reinforced with blocks to slow down the progress of scouring and extend the time until the levee breaks. This ensures the time (lead time) for evacuation.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, the overflow water has a high flow velocity and is accompanied by a very large impact force (water hammer) when it enters the blocks. Conventional blocks do not have a sufficient slope length to slow down the speed. Therefore, the invading overflow water hits the upstream block surface 100 and is vigorously discharged forward (see Fig. 7(b)). The forward discharge distance becomes longer as the water flow velocity increases. Furthermore, the newly generated water hammer after the discharge hits the second and third downstream blocks 110, disturbing the block row and leading to erosion of the slope surface. In addition, the water flow becomes turbulent and the vortices grow larger, increasing the scouring of the soil downstream of the blocks and causing water to enter under the blocks and lift them up. As described above, although countermeasures against overflow destruction are highly important, effective countermeasures are still insufficient. If the overflow continues, the levee will eventually break. Considering the time for maintaining the function of the levee and what measures can be taken to maintain the function of the levee for a long time for disaster prevention and mitigation is extremely important in considering the overflow resistance function of the levee.

[0009] The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to more effectively prevent a levee breach or extend the time until a levee breach occurs by attenuating the flow velocity of overtopping water when overtopping occurs. To provide a levee slope reinforcement structure, a levee slope reinforcement method, and a block mat for levee slope reinforcement.

Means for Solving the Problems

[0010] [1] A levee back slope reinforcement structure in which a plurality of reinforcement blocks are laid from the levee back slope to the levee back bottom, protecting the inner levee side slope against overtopping of a river, The plurality of reinforcement blocks include a first block provided on the most upstream side with respect to the overtopping, and a second block provided on the downstream side of the first block, The first block has an inclined surface on the upper surface such that the upstream side is closer to the bottom surface than the downstream side. The inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side. The first block is characterized in that the upstream end face is a convex curved surface in the levee back slope reinforcement structure. [2] In the first block, in a side view, the angle θ formed by the virtual inclined line S connecting the upstream end of the concave curved surface and the downstream end of the convex curved surface with the bottom surface is 5° to 30°. The levee back slope reinforcement structure according to [1]. [3] In the first block, in a side view, the maximum value t1 of the distance between the concave curved surface and the virtual inclined line S is 5% to 30% with respect to the height T of the inclined surface. The levee back slope reinforcement structure according to [1] or [2]. [4] The levee back slope reinforcement structure according to [3], wherein the t1 is 5 mm to 20 mm. [5] In the first block, in a side view, the maximum value t2 of the distance between the convex curved surface and the virtual inclined line S is 5% to 30% with respect to the height T of the inclined surface. The levee back slope reinforcement structure according to any one of [1] to [4]. [6] The dike backslope reinforcement structure according to [5], wherein t2 is 5 mm to 20 mm. [7] The dike backslope reinforcement structure according to any one of [1] to [6], wherein, in a side view, the ratio (l1:l2) of the length l1 of the concave curved surface to the length l2 of the convex curved surface of the first block is 1:3 to 3:1. [8] The dike backslope reinforcement structure according to any one of [1] to [7], wherein the plurality of reinforcing blocks are laid in a state of being adhered and fixed to a block mat sheet. [9] A dike backslope reinforcement method for protecting the dike inner side slope against river overtopping, comprising laying a plurality of reinforcing blocks across the dike backslope from the dike backslope to the dike backslope toe, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the overtopping and a second block provided on the downstream side of the first block, As the first block, the upper surface is an inclined surface that approaches the bottom surface more on the upstream side than on the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side and the upstream end face is a convex curved surface A dike backslope reinforcement method characterized by using blocks.

[10] A dike slope reinforcement structure in which a plurality of reinforcing blocks are laid on the dike slope to protect the dike slope against river flow, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the river flow and a second block provided on the downstream side of the first block, The dike slope reinforcement structure, wherein the first block has an inclined surface whose upper surface approaches the bottom surface more on the upstream side than on the downstream side, the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the upstream end surface is a convex curved surface.

[11] A dike slope reinforcement method for protecting the dike slope against river flow, comprising laying a plurality of reinforcing blocks on the dike backslope, The plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the river flow, and a second block provided on the downstream side of the first block. As the first block, the upper surface is an inclined surface that approaches the bottom surface more on the upstream side than on the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the end surface on the upstream side is a convex curved surface. A dike slope reinforcement method characterized by using a block.

[12] A dike slope reinforcement block mat in which a plurality of reinforcing blocks are adhered and fixed to a sheet for a block mat. The plurality of reinforcing blocks include a first block provided on the most upstream side with respect to overtopping or the river flow, and a second block provided on the downstream side of the first block. The first block is characterized in that the upper surface is an inclined surface that approaches the bottom surface more on the upstream side than on the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the end surface on the upstream side is a convex curved surface. A dike slope reinforcement block mat.

[13] The block mat sheet according to

[12] , which is selected from the group consisting of woven fabric, non-woven fabric, geogrid, and wire mesh, or a combination of two or more thereof.

Effect of the Invention

[0011] According to the present invention, when overtopping occurs, by attenuating the flow velocity of the overtopping water, it is possible to more effectively prevent dike breakage or extend the time until dike breakage, and to provide a dike slope reinforcement structure, a dike slope reinforcement method, and a dike slope reinforcement block mat.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0013] <First Embodiment> Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the back slope reinforcement structure of the dike of the present invention. This back slope reinforcement structure of the dike is a back slope reinforcement structure that protects the inner bank side slope against overtopping of a river, and a plurality of reinforcing blocks (the first block 10 and the second block 20) are laid from the back slope 50 of the dike to the back slope bottom 51. And in the back slope reinforcement structure of this embodiment, the plurality of reinforcing blocks include a first block 10 provided on the most upstream side with respect to overtopping or river flow, and a second block 20 provided on the downstream side of the first block. The first block 10 has an inclined surface 15 whose upper surface approaches the bottom surface 11 more on the upstream side than on the downstream side. The inclined surface 15 is characterized by having a concave curved surface 15a arranged on the upstream side and a convex curved surface 15b arranged on the downstream side (see FIGS. 3 and 4). Note that the "inner side of the dike" means the urban area side (the back side of the river), and the "outer side of the dike" means the river side (the front side of the river).

[0014] In this embodiment, among the plurality of reinforcing blocks (the first block 10 and the second block 20), the upper surface of the first block 10 provided on the most upstream side with respect to overtopping is made into an inclined surface 15 having a concave curved surface 15a and a convex curved surface 15b from the upstream side. By doing so, when overtopping occurs, the separated flow from the jet flow can be dispersed on the most upstream first block 10, and the hydraulic jump can be greatly reduced. That is, the uneven curved surface suppresses the splashing of water and allows the water to flow smoothly downward on the reinforcing block. Further, when overtopping occurs, the uneven curved surface on the upper surface of the block attenuates the flow velocity, and the progress of scouring at the toe of the dike can be suppressed. Also, the uplift of the block due to the entry of water under the block is prevented. As a result, dike breakage can be more effectively prevented, or the time until dike breakage can be extended.

[0015] In the dike inner slope reinforcement structure, a large number of reinforcing blocks (the first block 10 and the second block 20) may be directly arranged on the dike inner slope 50. However, laying a large number of blocks one by one is very time-consuming and laborious, and ultimately leads to an increase in cost.

[0016] Therefore, it is preferable to use a block mat 1 in which a plurality of reinforcing blocks (the first block 10 and the second block 20) are adhered and fixed to a block mat sheet 2. By using the block mat 1, the construction period can be significantly shortened, and costs such as labor costs can be reduced. Hereinafter, an embodiment in the case of using the block mat 1 will be described. Note that the description of the shape, arrangement, etc. of the reinforcing blocks described below can be directly applied to the dike inner slope reinforcement structure shown in FIG. 1 even in the case where the reinforcing blocks are directly laid on the slope 50 in a loose state, only differing in whether or not a plurality of reinforcing blocks (the first block 10 and the second block 20) are adhered and fixed to the block mat sheet 2.

[0017] First, the block mat 1 used in the dike back slope reinforcement structure of the present embodiment will be described. FIG. 2 is a view showing an example of the block mat 1 used in the present embodiment, where (a) is a plan view and (b) is a cross-sectional view. This block mat 1 is a block mat for dike back slope reinforcement, and a plurality of reinforcing blocks (the first block 10, the second block 20) are adhered and fixed to a block mat sheet 2 made of a soil particle-impermeable fabric having water permeability and flexibility. The reinforcing blocks are arranged in alignment with respect to the block mat sheet 2 and are integrally fixed by an adhesive or a fixing body.

[0018] The block mat sheet 2 has good water permeability to the ground surface through the sheet and has an erosion prevention function of preventing the soil on the ground surface from flowing out by the sheet, and a sheet having a filter effect is used. Here, the filter effect is an effect of preventing the permeation of soil while having water permeability. As the block mat sheet 2 having such an effect, a sheet having meshes such as a woven fabric or a knitted fabric is preferably used. The degree of the filter effect and the water permeability can be controlled by the size of the meshes. In the present embodiment, those having the following meshes are preferably used. 2 It preferably has the following meshes.

[0019] Furthermore, it is desirable that the sheet 2 for block mats is excellent in flexibility, conforms well to the ground surface, has good adhesion, and can be used even on soft ground where differential settlement may occur. Therefore, examples of the material for the sheet 2 for block mats include synthetic fibers, olefin fibers such as polyethylene fibers and polypropylene fibers, general-purpose fibers such as polyamide fibers, polyester fibers, polyvinylidene chloride fibers, and polyvinyl alcohol fibers, functional fibers such as carbon fibers and aromatic polyamides, natural fibers, and regenerated chemical fibers, and these may be used alone or in combination. Also, Taslan processed yarns or spun processed yarns may be used. The sheet 2 for block mats may be a woven fabric or a knitted fabric as long as it has a mesh, but in the sheet 2 for block mats according to the present invention, it is preferably a woven fabric with little elongation.

[0020] In the block mat 1 of the present embodiment, the plurality of reinforcing blocks may be arranged regularly or randomly. The arrangement itself of the plurality of reinforcing blocks in the block mat for reinforcing a dike slope is known. The number of blocks in the block mat 1 is not particularly limited. An appropriate number may be determined according to the size of the sheet 2 for block mats and the like. The plurality of reinforcing blocks are usually fixed to the surface of the sheet 2 for block mats.

[0021] In the block mat 1, the plurality of reinforcing blocks are roughly classified into a first block 10 provided on the uppermost stream side (the slope shoulder side) with respect to overtopping and a second block 20 provided on the downstream side of the first block 10.

[0022] And particularly in the present embodiment, in the first block 10 provided on the uppermost stream side with respect to overtopping, the upper surface is an inclined surface 15 that approaches the bottom surface 11 more on the upstream side than on the downstream side, and the inclined surface 15 is characterized by having a concave curved surface 15a arranged on the upstream side and a convex curved surface 15b arranged on the downstream side.

[0023] The "first block 10 provided on the uppermost stream side with respect to the cross-flow" refers to the block fixed to the uppermost front row (the side of the slope shoulder) above the block mat 1 when the block mat 1 is installed on the slope surface on the inside of the embankment. In other words, in the block mat 1, there are no blocks other than the first block 10 on the upstream side of the first block 10.

[0024] Figs. 3 and 4 show an example of the shape of the first block 10 (reinforcing block). Fig. 3 is a schematic perspective view, and Fig. 4 is a schematic side view. As shown in Figs. 3 and 4, the first block 10 has a flat bottom surface 11, an upstream end surface 12, a downstream end surface 13, and an upper surface. And the upper surface has a horizontal surface 14 substantially parallel to the bottom surface 11 and an inclined surface 15.

[0025] And in the first block 10, the inclined surface 15 has a concave curved surface 15a arranged on the upstream side and a convex curved surface 15b arranged on the downstream side instead of being a flat surface. In other words, in a side view, the inclined surface 15 depicts a gentle sine wave shape (one waveform).

[0026] Fig. 7 is a diagram schematically showing the flow of water on the reinforcing block, where (a) shows the reinforcing block of the present embodiment and (b) shows the conventional reinforcing block. In the present embodiment, by providing the inclined surface 15 of the uppermost upstream first block 10 with a concavo-convex curved surface shape (sine wave shape), when the cross-flow water intrudes with velocity and momentum, it rubs against the concavo-convex curved surface. That is, the separated flow from the jet flow is dispersed on the concavo-convex curved surface of the uppermost upstream first block 10, suppressing the splashing of water and allowing it to flow smoothly downward on the block. Thereby, the sliding length (the distance from when the cross-flow water jumps out from the first block 10 (100) into the air until it lands on the upper surface of the second block 20 (110) arranged on the downstream side) can be made shorter than the relaxation by the conventional flat inclined gradient.

[0027] In addition, water has viscosity and the property of flowing along the block mat 1. Therefore, in laminar flow, the shear layer thickness can be expected, and the rubbing length of the splashed water is suppressed. As a result, the impact force reaching the second block 20 at the rear is reduced. Furthermore, by making the upper surface of the first block 10 into a concavo-convex curved surface, the lift force of water is reduced. As a result, the overturning moment around the block's center of gravity becomes smaller, and the destruction of the block is suppressed. Also, the floating of the block due to water entering under the block is prevented.

[0028] In this way, in the present embodiment, when overtopping occurs, the concavo-convex curved surface of the upper surface of the first block 10 arranged on the most upstream side attenuates the flow velocity of the overtopping water, and the progress of scouring at the toe of the dike can be suppressed. As a result, the dike break can be more effectively prevented, or the time until the dike break occurs can be extended. Note that when the arrangement of the concave curved surface and the convex curved surface is reversed on the inclined surface 15 of the first block 10, that is, when the convex curved surface is arranged on the upstream side and the concave curved surface is arranged on the downstream side, the splashing of overtopping water cannot be suppressed, and the above-described effects cannot be obtained.

[0029] The upstream end face 12 (small end face) of the first block 10 is the region where the overtopping water first enters when overtopping occurs. The upstream end face 12 of the first block 10 is preferably a straight line or a convex curved surface with a rounded shape. Thereby, when overtopping occurs, the splashing of the overtopping water at the end face 12 can be suppressed and guided to the inclined surface 15 (concavo-convex curved surface) of the block. The end face 12 may be a gentle curved surface, or may have a steep angle of 70 to 90° with respect to the bottom face 11.

[0030] In a side view, the first block 10 preferably has an angle θ formed between the virtual inclined line (indicated by S in the figure) connecting the upstream end of the concave curved surface 15a and the downstream end of the convex curved surface 15b with a straight line and the bottom face 11 of 5° to 30°, and more preferably 10° to 25°. Thereby, when overtopping occurs, the overtopping water can be effectively dispersed on the concavo-convex curved surface, and the flow velocity can be more effectively attenuated. In addition, in FIG. 4, an auxiliary line P parallel to the bottom surface 11 is drawn.

[0031] In a side view, for the first block 10, the maximum value of the distance between the concave curved surface 15a and the virtual inclined line S (the distance indicated by t1 in FIG. 4) is preferably 5% to 30%, more preferably 7% to 23%, with respect to the height of the inclined surface 15 (indicated by T in FIG. 4). Thereby, when overtopping occurs, the overtopped water can be effectively dispersed on the concave and convex curved surfaces, and the flow velocity can be more effectively attenuated.

[0032] In the case of the block shown in FIG. 3, t1 is preferably, for example, 5 mm to 20 mm, more preferably 5 mm to 15 mm.

[0033] In a side view, for the first block 10, the maximum value of the distance between the concave curved surface 15a and the virtual inclined line S (the distance indicated by t1 in FIG. 4) is preferably 5% to 30%, more preferably 7% to 23%, with respect to the height T of the inclined surface 15. Thereby, when overtopping occurs, the overtopped water can be effectively dispersed on the concave and convex curved surfaces, and the flow velocity can be more effectively attenuated.

[0034] In the case of the block shown in FIG. 3, t2 is preferably, for example, 5 mm to 20 mm, more preferably 5 mm to 15 mm.

[0035] In a side view, for the first block 10, the ratio (l1:l2) of the length of the concave curved surface 15a (the length indicated by l1 in FIG. 4) to the length of the convex curved surface 15b (the length indicated by l2 in FIG. 4) is preferably 1:3 to 3:1, more preferably 1:2 to 2:1. Thereby, when overtopping occurs, the overtopped water can be effectively dispersed on the concave and convex curved surfaces, and the flow velocity of the overtopped water can be more effectively attenuated.

[0036] The dimensions of the first block 10 are not particularly limited, but from the viewpoint of suppressing peeling and destruction of the block due to overtopped water, the length of one side of the first block 10 is preferably 10 mm or more and 100 mm or less. In the case of the block shown in FIG. 3, the dimensions are, for example, width W: 39.8 cm, length D: 39.8 cm, and height H: 10.0 cm.

[0037] The material of the first block 10 having the above shape is not particularly limited. A material known as a revetment block may be adopted. For example, concrete, mortar, polymer cement mortar, stone, etc. can be adopted. The weight of the first block 10 is not particularly limited. For example, it can be 5 kg or more and 360 kg or less.

[0038] Regarding the second block 20, its shape and the like are not particularly limited. In the block mat 1, since sufficient measures are taken to attenuate the flow velocity by the first block 10, the shape and the like of the second block 20 can be designed relatively freely. Any known revetment block can be adopted for the second block 20. For example, various concrete blocks such as those used in Solcomat (registered trademark) manufactured by Asahi Kasei Advance Co., Ltd. can be adopted.

[0039] FIG. 5 is a diagram showing an example of the second block 20 (reinforcing block) used in the present embodiment. The lower part of the second block 20 in contact with the ground is formed in a conical or pyramidal shape, and the upper part is formed in a cylindrical or prismatic shape. From the viewpoint of suppressing the peeling and destruction of the block due to overflow water, the length of one side is preferably 19.0 cm or more and 100.0 cm or less. In the case of the block shown in FIG. 5, the dimensions are, for example, width w: 20.0 cm, length d: 20.0 cm, and height h: 10.0 cm.

[0040] The material of the second block 20 is such that the lower tip part is usually the same material as the upper part, or when there are hard stones or the like in the soft ground and there is a concern that the upper part may be chipped, the material is different from the upper part other than the tip part. Specifically, the upper part is made of concrete that is strong against compressive force, and the lower tip part is made of a metal or resin that has strong tensile strength and elasticity.

[0041] The shapes and sizes of the first block 10 and the second block 20 are not particularly limited, and blocks with shapes and dimensions other than the above examples can also be used. For example, from the viewpoint of solving the above problems, in the first block 10, the horizontal plane 14 is not necessarily required. That is, it may consist only of the inclined plane 15, but it is preferable that the first block 10 has the horizontal plane 14 on its upper surface.

[0042] For the adhesive fixation of the reinforcing blocks (the first block 10, the second block 20) made of concrete to the block mat sheet 2, usually, inorganic or organic adhesives, or adhesives mixed with these are used. As the inorganic adhesive, for example, hydraulic cement compositions such as mortar and concrete can be used. As the organic adhesive, those using thermosetting resins such as epoxy resin, urethane resin, acrylic resin, silicone resin, epoxy acrylate resin, and phenolic resin, those using thermoplastic resins such as polyamide resin, polyester resin, and ethylene vinyl alcohol resin, and those using synthetic rubbers such as styrene butadiene rubber, chloroprene rubber, and butyl rubber can be used, and an epoxy resin with excellent strength and curability is preferably used. Alternatively, after bringing the block mat sheet 2 into contact with the uncured concrete block, the concrete block may be adhered to the block mat sheet 2 by curing the concrete block.

[0043] Such a block mat 1 is laid from the back slope surface 50 of the levee to the toe portion 51. When laying the block mat 1, for example, as shown in Fig. 6, the end of the block mat 1 is laid along the crest part 51 of the revetment slope 50 of the dike. The length of the block mat 1 laid on the slope 50 is, for example, about 2 m along the slope 50. The block part may be fixed by driving the anchor pins 3 or the like. The foundation concrete 4 may be arranged at the end of the block mat 1 for end treatment or integrated with the crest part 51. Thereby, the block mat 1 can be firmly fixed, and the protective function of the back crest can be sufficiently exerted.

[0044] Also, when there is a flat end part following the crest part 51, it is preferable to protect the flat part with the block mat 1 from the slope 50 to the flat part. The scouring of the crest part 51 can be more reliably prevented. In this case, the length of the block mat 1 laid on the flat part is, for example, about 1.5 m along the flat part. Of course, even when laying the reinforcing blocks directly on the revetment slope 50 of the dike without using the block mat 1, the scouring of the crest part 51 can be more reliably prevented by laying the reinforcing blocks from the slope 50 to the flat part.

[0045] <Second Embodiment> In the above-described embodiment, the revetment slope reinforcement structure for protecting the inner-dike slope during overtopping of a river and the block mat 1 for reinforcing the revetment slope have been described. However, the use of the block mat 1 is not limited to the above. For example, the block mat 1 can also be used to protect the slope (which may be the outer-dike slope or the inner-dike slope) against the water flow of the river.

[0046] That is, the dike slope reinforcement structure according to the present embodiment is a dike slope reinforcement structure in which a plurality of reinforcing blocks are laid on the dike slope to protect the dike slope against the river flow. Among the plurality of reinforcing blocks, the reinforcing block (the first block 10) provided on the most upstream side with respect to the river flow has an inclined surface 15 on the upper surface, which approaches the bottom surface 11 more on the upstream side than on the downstream side. The inclined surface 15 is characterized by having a concave curved surface 15a arranged on the upstream side and a convex curved surface 15b arranged on the downstream side.

[0047] In this case, the block mat 1 or the reinforcing blocks (the first block 10 and the second block 20) may be laid on the entire slope surface of the river, or considering the cost aspect, etc., the block mat 1 or the reinforcing blocks may be laid on a part of the slope surface.

[0048] The levee slope reinforcement structure and the block mat according to this embodiment are the same as the levee back slope reinforcement structure and the block mat 1 according to the first embodiment, except that their uses, that is, the placement locations and orientations are different, and their structures and shapes themselves are the same as those of the block mat 1. Since the form of the levee slope reinforcement structure according to the second embodiment is obvious from the above description, the illustration is omitted here. Since the preferred form is the same as that of the first embodiment, the detailed description is omitted here.

[0049] As described above, also in the levee slope reinforcement structure in which the block mat 1 or the reinforcing blocks (the first block 10 and the second block 20) according to the second embodiment are laid on the slope surface of the river, the uneven curved surface of the first block 10 arranged on the uppermost stream side attenuates the water flow velocity with respect to the water flow of the river, so that the slope surface can be appropriately protected against the water flow.

Example

[0050] Hereinafter, examples and comparative examples conducted to confirm the effects of the present invention will be described. In the following examples, experiments were conducted using a 1 / 1 scale full-size model.

[0051] The experimental apparatus was fabricated indoors to avoid the influence of weather, outside air environment, etc. The experimental apparatus is composed of a circulation pump, an inflow water channel, a test water channel, a sedimentation basin, and a circulation water channel (not shown in the figure). The test water channel was a steel water channel with glass on both sides in part, with a width of 0.5 m, a height of 0.69 m, and a total length of 8.0 m (a slope angle of 30°, an inclined path of 4.0 m, and a horizontal part of 3.0 m). Sand was used with Nikko silica sand No. 4 (particle size distribution: median diameter 0.60 mm, coarse sand), and the upper surface was leveled and solidified in a water-compacted and saturated state.

[0052] (Example) As the first block, a block having the concavo-convex curved surface shown in FIGS. 3 and 4 was used, and as the second block, a block having the shape shown in FIG. 5 was used. The first block is made of styrofoam (extruded polystyrene heat insulating material) and the second block is made of concrete. The dimensions of the first block were length D: 33.5 cm, width W: 25.0 cm, height: 10.0 cm, weight 0.279 kg, θ: 14°, t1: 5 mm, t2: 10 mm, l1:l2 = 1:1, T: 50 mm. The dimensions of the second block were length d: 19.8 cm, width w: 19.8 cm, height h: 13.5 cm, and weight 7.8 kg. These first and second blocks were adhered and fixed onto the sheet for the block mat. An epoxy resin-based adhesive was used for adhering the blocks. At this time, as shown in FIG. 2, the first blocks were arranged in the lateral direction (direction parallel to the levee) on the most upstream side, and the second blocks were arranged in the other parts. In the above manner, a block mat was fabricated in which the blocks were arranged with 2 of the first blocks and 2.5 of the second blocks in the horizontal direction and 10 rows in the vertical direction.

[0053] (Comparative Example) A block mat was fabricated in the same manner as in the example, except that a trapezoidal block having a flat inclined surface instead of the concavo-convex curved surface was used as the first block in the most upstream side, and the first block was adhered and fixed onto the sheet for the block mat.

[0054] The block mats of each example and comparative example fabricated as above were laid on the levee of the experimental apparatus, and an overtopping experiment was conducted. Experimental flow rate corresponding to an overtopping water depth of 10 cm: 0.0029 m 3 / s (2.9 liters / s), and water was flowed through the experimental apparatus under this condition. The water volume increased at a constant rate, and the state with an overflow water depth of 10 cm was maintained for 15 minutes.

[0055] Figures 8 and 9 are photographs showing the movement of water flowing over the blocks during overflow for the example and the comparative example, respectively. As is clear from the photographs, in the comparative example (Figure 9) using a trapezoidal block for the uppermost upstream block, water splashes greatly on the slope, whereas in the example (Figure 8) using a block with a concavo-convex curved surface, it can be seen that the water is dispersed on the concavo-convex curved surface and the water splash is greatly reduced.

[0056] Also, the water was drained, and when the water volume reached 0, the shape of the sand surface was measured. In the example, the maximum flow velocity could be effectively decelerated, and local scouring in the portion near the back toe was effectively suppressed compared to the comparative example.

[0057] As described above, the embodiments of the present invention have been explained, but the present invention is not limited thereto and can be appropriately changed without departing from the gist of the invention.

Industrial Applicability

[0058] According to the present invention, when overflowing, the flow velocity of the overflow water can be attenuated, and it can be widely used as a reinforcing structure for the back slope of a levee.

Explanation of Signs

[0059] 1: Block mat for reinforcing the levee slope 2: Sheet for block mat 3: Anchor pin 4: Foundation concrete 10: First block (reinforcing block) 11: Bottom surface 12: Upstream end face 13: Downstream end face 14: Horizontal plane 15: Inclined plane 15a: Concave curved surface 15b: Convex curved surface 20: Second block (reinforcing block) 50: Back slope of levee 51: Toe of slope

Claims

1. A revetment slope reinforcement structure in which a plurality of reinforcing blocks are laid from the revetment slope surface to the revetment slope toe to protect the inner bank slope surface against overtopping of a river, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the overtopping and a second block provided on the downstream side of the first block, the first block has an inclined surface on the upper surface such that the upstream side is closer to the bottom surface than the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the first block is characterized in that the upstream end face is a convex curved surface.

2. The revetment slope reinforcement structure according to claim 1, wherein, in a side view, the angle θ formed between the virtual inclined line S connecting the upstream end of the concave curved surface and the downstream end of the convex curved surface with a straight line and the bottom surface is 5° to 30°.

3. In a side view, the maximum value t of the distance between the concave curved surface and the virtual inclined line S of the first block 1 is 5% to 30% with respect to the height T of the inclined surface, and the dike back slope reinforcement structure according to claim 1 or 2.

4. The aforementioned t 1 The dike back slope reinforcement structure according to claim 3, wherein the t is 5 mm to 20 mm.

5. In a side view, the maximum value t of the distance between the convex curved surface and the virtual inclined line S of the first block 2 is 5% to 30% with respect to the height T of the inclined surface, and the embankment back slope reinforcement structure according to any one of claims 1 to 4.

6. The aforementioned t 2 The revetment slope reinforcement structure according to claim 5, wherein t is 5 mm to 20 mm.

7. In a side view, the length l of the concave curved surface of the first block 1 and the length l of the convex curved surface 2 The ratio (l 1 : l 2 ) is 1:3 to 3:

1. The dike back slope reinforcement structure according to any one of claims 1 to 6

8. The revetment slope reinforcement structure according to any one of claims 1 to 7, wherein the plurality of reinforcing blocks are laid in a state of being adhered and fixed to a block mat sheet.

9. A revetment slope reinforcement method for protecting the inner bank slope surface against overtopping of a river by laying a plurality of reinforcing blocks from the revetment slope surface to the revetment slope toe, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the overtopping and a second block provided on the downstream side of the first block, the method is characterized in that, as the first block, a block having an inclined surface on the upper surface such that the upstream side is closer to the bottom surface than the downstream side, the inclined surface having a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the upstream end face being a convex curved surface is used.

10. A revetment slope reinforcement structure in which a plurality of reinforcing blocks are laid on the revetment slope to protect the revetment slope against river flow, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the river flow and a second block provided on the downstream side of the first block, the first block has an inclined surface on the upper surface such that the upstream side is closer to the bottom surface than the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and the first block is characterized in that the upstream end face is a convex curved surface.

11. A dike slope reinforcement method for protecting a dike slope against a river flow, in which a plurality of reinforcing blocks are laid on the back slope of the dike, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to the river flow and a second block provided on the downstream side of the first block, and as the first block, an inclined surface is provided on the upper surface such that the upstream side is closer to the bottom surface than the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and a block having a convex curved surface at the upstream end surface is used. The dike slope reinforcement method is characterized by this.

12. A block mat for dike slope reinforcement, in which a plurality of reinforcing blocks are adhered and fixed to a sheet for block mat, wherein the plurality of reinforcing blocks include a first block provided on the most upstream side with respect to overtopping or the river flow and a second block provided on the downstream side of the first block, and the first block has an inclined surface on the upper surface such that the upstream side is closer to the bottom surface than the downstream side, and the inclined surface has a concave curved surface arranged on the upstream side and a convex curved surface arranged on the downstream side, and a block having a convex curved surface at the upstream end surface. The block mat for dike slope reinforcement is characterized by this.

13. The block mat for dike slope reinforcement according to claim 12, wherein the sheet for block mat is one selected from the group consisting of woven fabric, non-woven fabric, geogrid, and wire mesh, or a combination of two or more thereof.

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