Earth flow prevention structure and construction method for constructing said structure

Abstract

To provide a sediment outflow prevention structure which can accurately prevent collapse of a sediment laminate formed by piling up sediments at the time of sediment outflow and in which an outer surface of the sediment laminate is covered with a net body, and a construction method for constituting the structure.SOLUTION: A sediment outflow prevention structure 10 includes a sediment laminate 20 where sediments 22 are piled up on a slope S in a vertical direction in a plurality of stages, and a net body 30 fixed to the slope in the state where an outer surface of the sediment laminate is covered, and prevents sediment outflow from the slope by the sediment laminate, wherein the net body has a sediment mounted area part 34 which is laid on the slope and where the sediment laminate is mounted on an upper surface, a mountain side area part 32 which extends to a slope mountain side in the sediment mounted area and is fixed to the slope, and a sediment covering area part 36 which extends to a slope valley side of the sediment mounted area, and is folded so as to cover at least an upper surface of the mounted sediment laminate and is fixed to the mountain side area part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a structure for preventing soil erosion and a construction method for constructing the structure, and more particularly to a structure for preventing soil erosion on a slope using sandbags and a construction method for constructing the structure. [Background technology]

[0002] When heavy rain falls on mountain slopes, rainwater tends to flow into areas that are lower than the surrounding ground. If this situation continues for a long period of time, the slope will be eroded and a stream will form. When rain falls, soil will flow out along the stream, raising concerns that a landslide will occur.

[0003] As a method for preventing such soil outflow, a method is known in which sandbags are piled up on the slope to prevent soil outflow from the top of the slope.

[0004] For example, Patent Document 1 discloses a structure for preventing soil outflow, in which a sandbag stack is installed in the lower slope area, in which sandbags are stacked vertically in multiple layers to form a wall, and this sandbag stack prevents landslides, avalanches, etc. that occur on the slope from flowing into the slope valley. This sandbag stack is supported by a support fence erected adjacent to the slope valley side, preventing the sandbags from moving toward the valley and collapsing the sandbag stack when it receives an impact force from soil. The support fence is firmly erected with its posts buried deep in the ground so that it can fully withstand the impact force acting on the sandbag stack.

[0005] In the soil erosion prevention structure described in Patent Document 1, the support fence can prevent the sandbag stack from collapsing when soil erodes, but the support posts need to be buried deep into the ground, which creates the problem of long construction times and costs.

[0006] As a method for reducing construction time and costs, a method of fixing a sandbag stack to the ground using a mesh body is known.

[0007] For example, Patent Document 2 discloses an installation structure for a stack of sandbags, the outer surfaces of which are covered with a net and fixed to the ground. The front, top and back of the stack of sandbags are covered with a central net body, which is a series of net bodies, and the left and right sides of the stack of sandbags are covered with a left net body and a right net body, which are net bodies connected to the central net body, respectively. The lower end of the central net body is fixed to the ground by an anchor bolt.

[0008] With this structure, the sandbag stack is covered with a mesh body to integrate the multiple stacked sandbags, and the mesh body allows the sandbag stack to be pressed against the ground and fixed in place, preventing the sandbag stack from collapsing or being swept down the slope valley when subjected to the impact force of a debris flow. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6024958 [Patent Document 2] Patent No. 6766307 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the soil erosion prevention structure described in Patent Document 2, when a large amount of soil flows out, the pressing force of the mesh body by the anchor bolts alone is not sufficient to withstand the impact force acting on the slope valley side, and the sandbags may shift from their designated positions, leading to the collapse of the sandbag stack.

[0011] Therefore, there was a need to develop technology that could more firmly secure a stack of sandbags to a slope using a simple fixing structure using a mesh, thereby preventing the stack of sandbags from collapsing.

[0012] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a soil erosion prevention structure in which the outer surface of a sandbag stack formed by stacking sandbags is covered with a mesh body, which can accurately prevent the collapse of the sandbag stack in the event of a soil erosion, and a construction method for constructing such a structure. [Means for solving the problem]

[0013] In order to achieve the above object, the earth and sand runoff prevention structure according to claim 1 of the present application comprises: A structure for preventing soil erosion comprises a sandbag stack in which sandbags are stacked vertically on a slope in a number of stages, and a net body fixed to the slope while covering the outer surface of the sandbag stack, the net body preventing soil erosion from the slope by the sandbag stack, The soil and sand flowing out from a slope above the sandbag stack due to a collapse of a ground slope and being blocked by the sandbag stack, The mesh body is A sandbag placement area is laid on the slope and has the sandbag stack placed on its upper surface; The sandbag placement area is extended to the mountain side of the slope, With the sediment on the top surface, the end of the slope on the mountain side a mountain side area portion fixed to the slope; A sandbag covering area is provided on the slope valley side of the sandbag placement area, folded back so as to cover at least the upper surface of the stack of sandbags placed on the slope valley side, and fixed to the mountain side area. a soil covering area portion having an end portion on the slope valley side connected to the sandbag covering area portion and covering the outer surface of the accumulated soil, and an end portion on the slope mountain side fixed to a position above the area where the accumulated soil is present on the slope; The present invention is characterized by having the following.

[0014] With this configuration, when soil and sand flow out from the slope and is blocked by the sandbag stack, the soil and sand accumulates on the upper part of the mountain side area and on the mountain side of the sandbag covered area. The weight of this accumulated soil presses the mountain side area, which is fixed to the slope, even more strongly against the ground slope, increasing the fixing force to the slope. The mountain side of the sandbag covered area is also firmly pressed against the sandbags. This allows the fixing force of the mesh body to the stack of sandbags during a soil erosion to be increased compared to before the soil erosion, effectively preventing the collapse of the stack of sandbags during a soil erosion.

[0015] The invention according to claim 2 is the structure for preventing soil erosion according to claim 1, The mesh body Sandbag placement area, mountain side area and sandbag cover area is formed by an integral mesh member.

[0016] With this configuration, the upper area of ​​the mesh body can be laid on the slope to form the mountain side area and the sandbag placement area, and then the lower area of ​​the mesh body can be folded back toward the mountain side of the slope to form the sandbag covering area, making it easy to form each area of ​​the mesh body.

[0017] The invention according to claim 3 is the structure for preventing soil erosion according to claim 1, The mesh body Sandbag placement area, mountain side area and sandbag cover area is formed by connecting a plurality of mesh members.

[0018] With this configuration, the mesh members can be appropriately connected to form the mountain side area, sandbag placement area and sandbag covering area of ​​the mesh body to appropriate sizes depending on the size of the sandbag stack and the conditions at the installation site.

[0019] The invention according to claim 4 of the present invention is a structure for preventing soil erosion according to any one of claims 1 to 3, The sandbag stack is characterized by having a water pipe passing through it from the mountain side of the slope to the valley side of the slope.

[0020] This structure allows the moisture contained in the soil blocked by the stack of sandbags to escape through the water pipes that pass through the stack of sandbags to the slope valley side, reducing the load that the stack of sand receives from the soil it blocks, making it possible to block more soil while preventing the stack of sandbags from collapsing.

[0021] The invention according to claim 5 of the present invention is a structure for preventing soil erosion according to any one of claims 1 to 4, The sandbag comprises a bag body and a filling material enclosed inside the bag body, The bag body has water permeability, The filler is characterized in that it is made up of granules having an average particle size of 3 mm to 15 mm.

[0022] With this configuration, the average particle size of the granules that make up the filling material is relatively large, and moisture can pass between the granules, allowing the moisture contained in the soil blocked by the stack of sandbags to pass through the sandbags and flow to the valley side of the stack of sandbags. This reduces the load that the stack of sand receives from the blocked soil, making it possible to block more soil while preventing the stack of sandbags from collapsing.

[0023] The invention according to claim 6 of the present invention is the structure for preventing erosion of soil according to claims 1 to 4, The sandbag comprises a bag body and a filling material enclosed inside the bag body, The bag body has water permeability, The filling material is characterized by containing a hardening material which hardens upon reacting with moisture.

[0024] With this configuration, when the stack of sandbags is installed, the hardened material that makes up the filling material is in an unhardened state and the shape of the sandbags is not fixed, so multiple sandbags can be stacked without gaps. After the stack of sandbags is installed, the stack of sandbags is used to hold back the soil, and the moisture contained in the soil hardens the filling material in the sandbags. As the filling material hardens, the shape of the sandbags is fixed and displacement between the sandbags is less likely to occur, making the stack of sandbags less likely to collapse.

[0025] The invention according to claim 7 of the present invention is a structure for preventing soil erosion according to any one of claims 1 to 6, The mesh body is characterized in that it has an additional mesh body portion that is laid between the top and bottom of the sandbags which are stacked vertically, covers the bottom and top of the sandbags, and is connected to the sandbag covering area portion of the mesh body.

[0026] With this configuration, the additional mesh portion can separately support the sandbag stacks installed in multiple tiers, and by connecting the additional mesh portion to the sandbag covering area of ​​the mesh body, the multiple tiers of sandbags are integrated, preventing the sandbags from collapsing in each tier.

[0027] The invention according to claim 8 of the present invention is a structure for preventing soil erosion according to any one of claims 1 to 7, The sandbag stack and the sand that is blocked by the sandbag stack The above A sandbag stack is provided in which a plurality of sandbags are stacked in a wall shape above the accumulated soil, The mesh is disposed on the outer surface of the post-installation sandbag stack from the sandbag covering region. Face It is characterized by having an additional sandbag covering area portion that covers and is fixed to the mountain side area portion.

[0028] According to this configuration, after a sediment flow that has occurred on a slope is blocked by the sandbag stack, the blocked sediment can be used to install a retrofit sandbag stack above the accumulated sediment and the existing sandbag stack, thereby blocking more sediment. The retrofit sandbag stack is integrated with the existing sandbag stack with its outer surface covered by the additional sandbag covering area together with the accumulated sediment, so it has a high fixing force against the slope and can properly block any sediment flow that occurs thereafter.

[0029] The invention according to claim 9 of the present invention is a construction method for constructing the soil outflow prevention structure according to any one of claims 1 to 8, laying the net on the slope; A step of piling up a plurality of sandbags on the upper surface of the lower slope area of ​​the laid net body to form the sandbag stack, and forming the sandbag placement area and the mountain side area of ​​the net body; a step of extending the net from the end of the sandbag placement area on the slope valley side to cover the outer surface of the sandbag stack and connect to the mountain side area to form the sandbag covering area of ​​the net; After the accumulated soil is placed in the mountain side area, the net is extended from the sandbag placement area to cover the outer surface of the sandbag stack, forming the soil covering area of ​​the net; The present invention is characterized by comprising:

[0030] With this configuration, a soil erosion prevention structure comprising a mesh body having the above-mentioned sandbag placing area, mountain side area and sandbag covering area can be easily constructed on a slope. Effect of the Invention

[0031] According to the soil erosion prevention structure and the construction method for constructing the structure of the present invention, when soil is blocked by the stacked sandbags, the weight of the blocked soil presses the mountain side area of ​​the mesh against the ground slope, increasing the fixing force to the slope, and the mountain side of the sandbag covering area also increases the fixing force to the slope. This makes it possible to increase the fixing force of the stacked sandbags by the mesh when soil erodes compared to before soil erosion, and to reliably prevent the collapse of the stacked sandbags when soil erodes. [Brief description of the drawings]

[0032] [Figure 1] 1 is a partially cross-sectional side view showing a schematic diagram of a soil outflow prevention structure according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view of the soil outflow prevention structure shown in FIG. 1. [Diagram 3] FIG. 1 is an explanatory diagram of a construction method for preventing soil erosion. [Figure 4] 5 is a partially cross-sectional side view showing a schematic diagram of a soil outflow prevention structure according to a second embodiment of the present invention. FIG. [Diagram 5] FIG. 11 is a partially cross-sectional side view that illustrates a schematic diagram of a soil outflow prevention structure according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Fig. 1 is a partially sectional perspective view showing a schematic diagram of a soil erosion prevention structure according to a first embodiment of the present invention, and Fig. 2 is a perspective view of the soil erosion prevention structure shown in Fig. 1. The soil erosion prevention structure 10 uses sandbags 22 to prevent the outflow of soil, avalanches, and the like that occur on sloping land such as mountains.

[0034] The soil runoff prevention structure 10 of this embodiment is installed on a slope S serving as the ground, and includes a sandbag stack 20 formed by stacking a plurality of sandbags 22, a net 30 covering the sandbag stack 20, a fastener 40 for fixing the net 30 to the ground slope S, and support ropes 52, 54. The net 30 has a sandbag placement area 34 and a mountain side area 32 laid on the slope S, and a sandbag covering area 36 covering the sandbag stack 20. In this embodiment, the slope S is a natural ground slope, but is not limited thereto, and may be an embankment slope or a slope. Note that FIG. 1 shows a state in which the runoff soil 60 is blocked by the sandbag stack 20, and FIG. 2 shows the runoff soil 60 by imaginary lines.

[0035] The sandbag stack 20 is a stack of multiple sandbags 22 stacked in a wall shape. As shown in Fig. 2, the sandbag stack 20 of this embodiment is stacked vertically with multiple sandbags 22 lined up in the width direction of the slope S so as to have a predetermined width on the slope S. In this embodiment, a water passage pipe 48 is provided in the sandbag stack 20 as shown in Fig. 1. Note that the water passage pipe 28 is omitted from Fig. 2.

[0036] Each sandbag 22 comprises a hollow bag body 24 and a filler 26 sealed inside the bag body 24. The bag body 24 can be formed by forming a nonwoven fabric, a woven fabric, a vinyl sheet, or the like into a bag shape. It is preferable that the bag body 24 be made of, for example, a woven fabric, so that it has water permeability.

[0037] As the filling material 26, for example, soil or gravel can be used. When using a water-permeable bag body 24, it is preferable to use a hard granular material having a higher porosity than soil as the filling material 26. As the hard granular material having a higher porosity, for example, gravel, crushed stone, boulders, concrete rubble, etc. can be used alone or in combination. In order to obtain the required porosity, it is preferable that the average particle size of the granular material constituting the filling material 26 is set in the range of about 3 mm to about 15 mm. Here, the average particle size is the volume average diameter obtained by weighting the particle diameter of the granular material by volume.

[0038] In this embodiment, granular material with an average particle size of 3 mm to 15 mm is used as the filling material 26. In this way, the bags 24 and the filling material in the bags 24 have water permeability, so that when the sand is blocked by the sandbag stack 20, the moisture inside the blocked sand seeps out through the sandbag stack 26 to the valley side of the slope S. This allows the moisture in the sand to pass through the sandbag stack 20 and be discharged to the valley side of the slope S.

[0039] The filling material 26 is not limited to this, and may be configured to include a hardening material that reacts with moisture to harden. For example, cement or the like can be used as such a hardening material. When the bag body 24 has water permeability and a mixture of earth and sand and cement, which is a hardening material, is used as the filling material 26, the cement constituting the filling material 26 is in an unhardened state when the sandbag stack 20 is installed, and the shape of each sandbag 22 is not fixed, so that multiple sandbags 22 can be stacked side by side without gaps. In addition, the unhardened and soft filling material 26 can be deformed to fit the topography of the installation site. After the sandbag stack 20 is installed, the sand is blocked by the sandbag stack 20, and the moisture contained in the earth penetrates into the bag body 24 of the sandbag 22 and reacts with the cement, causing the filling material 26 to harden. As the filling material 26 hardens, the shape of each sandbag 22 is fixed and the sandbags 22 are less likely to shift in position, making the sandbag stack 20 less likely to collapse and improving the sand and soil absorption capacity of the sandbag stack 20.

[0040] The water pipe 48 is a pipe that penetrates the sandbag stack 20 from the mountain slope side to the valley slope side (i.e., penetrates the thickness direction of the wall-shaped sandbag stack 20), and can be formed of, for example, a resin or metal pipe. The water pipe 48 can be installed so as to pass between adjacent sandbags 22 when the sandbag stack 20 is formed. The number and diameter of the water pipes 48 can be set appropriately, and for example, the inner diameter of the water pipes 48 can be set to, for example, 2 cm to 3 cm. When multiple water pipes 48 are provided, it is also possible to change the pipe diameter of the water pipes 48 depending on the location. By appropriately setting the inner diameter of the water pipes 48 to discharge a certain amount of water, it is possible to gradually discharge the moisture contained in the blocked soil over time. In addition, by discharging the moisture in the soil in this way, the water pressure on the sandbag stack 20 can be reduced.

[0041] The mesh body 30 is formed by weaving metal wires. In this embodiment, the wires forming the mesh body 30 are made of hard steel wires, have a diameter of 2 mm to 5 mm, and have a strength of 800 N / mm 2 ~2000N / mm 2 Such a wire may be, for example, a wire made from a hard steel wire specified in JIS G 3506, such as a hard steel wire (JIS G 3521) or a galvanized steel wire (JIS G 3548). The wire 24 made from a hard steel wire may be a wire made from a soft steel wire specified in JIS G 3505, that is, a commercially available iron wire made from a soft steel wire (generally having a tensile strength of 290 to 540 N / mm 2 Compared to general-purpose wire mesh made of cellulose ether (which is a fibrous material), it is less susceptible to plastic deformation and has high tensile strength and springiness.

[0042] The mesh body 30 of this embodiment is a diamond-shaped wire mesh having diamond-shaped meshes, as shown in Fig. 2. The mesh shape of the mesh body 30 is not limited to diamond shape, and can be appropriately set, for example, circular. The mesh body 30 preferably has a zinc plating layer or a zinc-aluminum alloy plating layer on the surface.

[0043] The wires forming the mesh body 30 are not limited to those made of metal, and may be wires made of carbon fiber, glass fiber, aramid fiber, or the like, or wires made of highly corrosion-resistant resin. Also, the mesh body 30 may be a high-strength mesh-like woven fabric (geogrid) made of resin.

[0044] The net body 30 can be formed by an integral net member. When the net body 30 is formed by an integral net member 30, the mountain side region 32, the sandbag placement region 34, and the sandbag cover region 36 of the net body 30 can be easily formed. Alternatively, the net body 30 may be formed by connecting a plurality of net members. The plurality of net members can be easily connected by using a linear material such as a wire. When the net body 30 is formed by a plurality of net members, the mountain side region 32, the sandbag placement region 34, and the sandbag cover region 46 of the net body 30 can be formed to an appropriate size by appropriately connecting the net members according to the size of the sandbag stack 20 and the situation at the installation site. When a plurality of net members are connected to form a continuous net body 30, the material can be changed for each connected net member. For example, it is possible to form a part of the net body 30 by a net member made of hard steel wire, and the remaining part by a net member made of a high-strength mesh-like fabric.

[0045] The mesh body 30 has a sandbag placing area 34 on which the sandbag stack 20 is placed, a mountain side area 32 extending from the slope side of the sandbag placing area 34 and fixed to the slope S, and a sandbag covering area 36 extending from the slope valley side of the sandbag placing area 34 and folded back to cover at least the upper surface of the sandbag stack 20 and fixed to the mountain side area 32.

[0046] The mountain side region 32 and the sandbag placement region 34 of the net body 30 are regions laid on the slope S, and the mountain side region 32 is a non-sandbag placement region where the sandbags 22 are not placed. The mountain side region 32 is connected to an end 34b of the sandbag placement region 34 on the mountain side of the slope, and spreads from the sandbag placement region 34 upward of the slope S. As shown in FIG. 1, in this embodiment, the mountain side region 32 and the sandbag placement region 34 of the net body 30 are fixed to the slope S by a fastener 40, but the sandbag placement region 34 may be configured to be fixed to the slope S by the weight of the sandbag stack 20 without using the fastener 40.

[0047] The sandbag covering area 36 of the net body 30 is an area in which the end 36a on the slope valley side (hereinafter also referred to as the "valley side end 36a") is connected to the end 34a on the slope valley side of the sandbag placing area 34, covers the outer surface of the sandbag stack 20, and extends to the mountain side area 32. The sandbag covering area 36 of this embodiment covers the wall surface on the slope valley side and the top surface and the wall surface on the slope mountain side of the sandbag stack 20. The end 36b on the slope mountain side of the sandbag covering area 36 (hereinafter also referred to as the "mountain side end 36b") is fixed to the slope S in a state where it is overlapped on the mountain side area 32.

[0048] The net body 30 has an additional net body portion 60 that is laid between the upper and lower sandbags 22 that are stacked in the vertical direction, covers the lower and upper surfaces of the sandbags 22, and is connected to the sandbag covering area portion 36 of the net body 30. In this embodiment, in the sandbag stack 20, the additional net body portions 60-1, 60-2 are installed between each of the layers of the sandbags 22 that are stacked vertically, and the ends of each of the additional net body portions 60-1, 60-2 are connected to the sandbag covering area portion 36. The additional net body portion 60 is optional, and the configuration may not include this, but by providing the additional net body portion 60, each layer of the sandbag stack 20 that is installed in multiple layers can be supported separately. In addition, by connecting the additional net body portion 60 to the sandbag covering area portion 36 of the net body 30, the multiple layers of sandbags 22 can be integrated, and the collapse of the sandbags in each layer is suppressed. This makes it possible to more effectively prevent the sandbags 22 from collapsing when a load of soil and sand acts on the sandbag stack 20.

[0049] The net body 30 shown in FIG. 1 is formed by a first net member 30A and a second net member 30B connected thereto. The first net member 30A is formed in a substantially rectangular shape, with one end side in the length direction of the rectangle forming the mountain side region 32, the other end side forming a part of the sandbag covering region 36 and the first additional net body portion 60, and the region between them forming the sandbag placing region 34 (see FIG. 3(B)). The second net member 30B forms the remaining part of the sandbag covering region 36, and covers the outer surface of the sandbag stack 20 that is not covered by the first net member 30A (see FIG. 3(C)). In this embodiment, the first and second net members 30A and 30B are formed from net members of the same material (i.e., net members made of hard steel wire).

[0050] The net body 30 is fixed to the slope S by using anchor members 42. For example, anchor pins, lock bolts, etc. can be used as the anchor members 42. In this embodiment, the net body 30 is fixed to the slope S by a fastener 40 including the anchor members 42, a plate member 44, and a nut member 46. FIG. 2 shows a state in which the mountain side region 32 and the periphery of the sandbag placement region 34 of the net body 30 and the center of the mountain side region 32 are fixed by the fastener 40. FIG. 1 also shows a state in which the mountain side end 36b of the sandbag covering region 36 of the net body 30 is fixed by the fastener 40 while overlapping the mountain side region 32.

[0051] The net body 30 is pressed against the slope S and fixed by a plate material 44 fixed to the head of the anchor member 42 by a nut member 46. In this embodiment, a cap nut equipped with a cap that covers the head of the anchor member 40 is used as the nut member 46.

[0052] The plate material 44 is a plate material having a through hole formed in the center through which the anchor member 42 is inserted, and can be formed, for example, from a steel plate or a resin plate with a reinforcing material embedded therein. The plate material 44 is formed so that the length of the major axis (length in the long direction) is larger than the mesh of the mesh body 30 in a plan view. The plate material 44 can adopt various shapes such as a circle, an ellipse, a polygon, etc. in a plan view, and is formed in a quadrangle in this embodiment. It is preferable that one or more protrusions protruding from the lower surface are formed on the lower surface side of the plate material 44. The length of the protrusions is set to be equal to or greater than the thickness of the mesh body 30.

[0053] The plate material 44 is placed on top of the mesh body 30 with the anchor members 42 passing through the through holes, and is positioned so that the protrusions provided on the underside of the plate material 44 penetrate the mesh of the mesh body 30. The plate material 44 is fixed to the head of the anchor member 40 by a nut member 46 fastened to the top of the anchor member 42. By having the protrusions of the plate material 44 inserted into the mesh of the mesh body 30 in this manner, when an external force is applied to the mesh body 30 and the relative positions of the plate material 44 and the mesh body 30 tend to shift, the engagement structure between the protrusions of the plate material 44 and the linear members constituting the mesh body 30 can prevent the mesh body 30 from shifting in position.

[0054] A shock absorber (not shown) for wear resistance can be placed between the plate material 44 and the net body 30. The shock absorber can be made of, for example, a rubber material or a resin material, and can be a coating integrally formed on the surface of the plate material 44. A sheet-like shock absorber separate from the plate material 44 can also be placed between the net body 30 and the plate material 44, and in such a case, it is preferable that the shock absorber has softness.

[0055] The support ropes 52, 54 are stretched from anchors 56 fixed to the ground slope S to the upper and lower parts of the slope valley side of the sandbag covered area 36 of the net body 30. The support ropes 52, 54 support the net body 30 integrated with the sandbag stack 20 by pulling the sandbag covered area 36 in the width direction of the slope S and toward the mountain side of the slope. In the illustrated example, an upper support rope 52 that supports the upper side of the sandbag covered area 36 and a lower support rope 54 that supports the lower side are described. Each support rope 52, 54 is installed so as to pull the sandbag covered area 36 of the net body 30 toward the mountain side of the slope. These support ropes 52, 54 are optional, and for example, it is also possible to later attach the support ropes 52, 54 to the net body 30 to reinforce the sandbag stack 20 after a small amount of soil and sand has been dammed by the sandbag stack 20.

[0056] Next, a method for constructing the above-mentioned soil outflow prevention structure 10 will be described with reference to FIG.

[0057] First, as shown in FIG. 3(A), the net body 30 is laid on the ground slope S so that the mountain side region 32 and the sandbag placement region 34 of the net body 30 are formed (net body laying process). The laid net body 30 is fixed to the ground slope S using the fixing device 40. In this embodiment, a plurality of anchor members 42 are driven into the net body laying region of the slope S at intervals, and then the net body 30 is spread on the slope S and the heads of the anchor members 42 are passed through the meshes of the net body 30. Next, a plate member 44 is attached to the heads of the anchor members 42 from above the net body 30, and the nut members 46 are fastened to fix the plate member 44 to the heads of the anchor members 40. As a result, the net body 30 is fixed to the slope S by the anchor members 42.

[0058] Next, as shown in FIG. 3(B), a plurality of sandbags 22 are piled up on the upper surface of the area below the slope S of the laid net body 30 to form the sandbag stack 20 (sandbag stack forming process). As a result, the area of ​​the laid net body 30 where the sandbag stack 20 located on the lower side of the slope S is placed becomes the sandbag placement area 34, and the area above the slope S becomes the mountain side area 32 where the sandbags 22 are not placed. In this embodiment, the sandbag stack 20 forming process is performed by first forming the first layer of sandbags 22, laying the additional net body part 60-1 of the net body 30 on the upper surface of the first layer of sandbags 22, and placing the second layer of sandbags 22 on top of it. Then, laying the additional net body part 60-2 on the upper surface of the second layer of sandbags 22, and placing the third layer of sandbags 22 on top of it. As a result, the additional net body part 60 is arranged between the sandbags 22 of each layer. In this embodiment, the mesh 30 is folded back on the mountain slope side and the valley slope side each time a stage is formed so that the additional mesh portion 60 is laid between the sandbags 22 of each stage.

[0059] Next, as shown in FIG. 3(C), the net body 30 is extended from the valley side end 34a of the sandbag placing area 34 so as to cover the outer surface of the sandbag stack 20 and connect to the mountain side area 32, forming the sandbag covering area 36 of the net body 30 (sandbag covering process with the net body 30). In this embodiment, a part of the outer surface of the sandbag stack 20 is covered by the first net body part 30A, so the remaining uncovered part is covered by the second net body part 30B. In the example shown in FIG. 3(C), a part of the wall surface on the slope valley side of the sandbag stack 20 is not covered by the first net body 30A, so this part is covered by the second net body part 30B. As a result, the wall surface on the slope valley side, the upper surface, and the wall surface on the slope mountain side of the sandbag stack 20 are covered by the sandbag covering area 36 of the net body 30. The mountain side end 36b of the sandbag covering area 36 is fixed to the slope S using fasteners 40 while overlapping the mountain side area 32.

[0060] In the process of forming the sandbag stack 20 shown in Fig. 3(B), the additional net body parts 60 between each stage may be formed of separate net members, not a continuous one. In such a case, in the subsequent sandbag covering process, the peripheral parts of the additional net body parts 60-1, 60-2 are connected to the sandbag covering area part 36 of the net body 30 by linear materials such as wires.

[0061] When the additional mesh body 60 is not provided to the sandbag stack 20, the mountain side area 32, the sandbag placing area 34 and the sandbag covering area 36 can be formed by only the series of first mesh body parts 30A. Specifically, after forming the sandbag stack 20, the area on one end side of the longitudinal direction of the first mesh body part 30A (the area on the slope valley side) can be folded back to the slope mountain side so as to cover the outer surface of the sandbag stack 20, thereby forming each of the areas 32, 34, 36.

[0062] After covering the sandbag stack 20 with the sandbag covering area 36, ​​one end of the upper support rope 52 is attached to the upper part of the net 30 covering the valley side wall of the sandbag stack 20, one end of the lower support rope 54 is attached to the lower part of the net 30 covering the valley side wall of the sandbag stack 20, and the other ends of each support rope 52, 54 are attached to anchors 56 fixed to the ground slope S to suspend each support rope 52, 54 (support rope installation process). As a result, the soil outflow prevention structure 10 shown in FIG. 2 is installed on the slope S.

[0063] In the above-mentioned soil outflow prevention structure 10, when a ground slope collapses due to rainfall or the like and a soil flow occurs on the slope S, the soil that flows out is blocked by the wall-like sandbag stack 20 installed on the slope S. The blocked sediment 70 is deposited on the mountain side area 32 and the sandbag covering area 36 of the mesh body 30, and the weight of this deposited soil 60 presses the mountain side area 32 even more strongly against the ground slope S, increasing the fixing force to the slope S. In addition, the mountain side portion of the sandbag covering area 36 is also firmly pressed against the sandbags 22. As a result, the fixing force of the sandbag stack 20 to the slope S by the mesh body 30 is stronger than before the soil outflow. In this way, the soil erosion prevention structure 10 of this embodiment has a structure in which the mesh body 30 covering the sandbag stack 20 is simply fixed to the ground slope 30 using anchor pins or the like, yet the construction strength of the sandbag stack 20 can be increased by utilizing the eroded soil 60, and the collapse of the sandbag stack 20 can be effectively prevented in the event of soil erosion.

[0064] In addition, in the soil outflow prevention structure 10 of this embodiment, since the sandbags 22 constituting the sandbag stack 20 have water permeability, the moisture contained in the blocked soil passes through the sandbag stack 20 and is discharged to the slope valley side of the sandbag stack 20. This allows the sandbag stack 20 to block more soil.

[0065] Furthermore, in this embodiment, the sandbag stack 20 is provided with a water pipe 48, so that the moisture contained in the blocked soil can escape through the water pipe 48 to the slope valley side of the sandbag stack 20. This reduces the load that the sandbag stack 20 receives from the blocked soil, allowing more soil to be blocked.

[0066] Next, another embodiment of the soil flow prevention structure 10 will be described with reference to Fig. 4. In the soil flow prevention structure 10 shown in Fig. 4, the same reference numerals are used for the parts corresponding to those in the first embodiment described above, and the details of the same configurations as those in the first embodiment will be omitted.

[0067] In this embodiment, the sediment 70 blocked by the sandbag stack 20 is used as part of the sediment runoff prevention structure 10. The net body 30 has a sediment-covered area 37 that covers the outer surface of the sediment 70. The sediment-covered area 37 is an area that is extended from the sandbag-covered area 36 to the mountain slope in the net body 30. The end of the sediment-covered area 37 on the valley side of the slope is connected to the sandbag-covered area 36 of the net body 30, and the end of the sediment-covered area 37 on the mountain slope is fixed to the slope S using a fixing device 40. In this embodiment, the mountain side end of the sediment-covered area 37 is fixed to the slope S in a state where it overlaps with the mountain side area 32 of the net body 30. The mountain side area 32 of the net body 30 can be appropriately added after the sediment 70 is formed to expand the installation area.

[0068] In this way, after the soil and sand have been blocked by the sandbag stack 20, the accumulated soil and sand 70 can be covered with the mesh body 30 and integrated with the existing sandbag stack 20, so that the accumulated soil and sand 70 can be used as part of the soil erosion prevention structure 10 to prevent any subsequent soil and sand erosion.

[0069] Next, a second embodiment of the soil erosion prevention structure 10 will be described with reference to Fig. 5. In the soil erosion prevention structure 10 shown in Fig. 4, the same reference numerals are used for the parts corresponding to those in the first embodiment, and the details of the same configurations as those in the first embodiment will be omitted. Note that the water pipe 48 is not shown in Fig. 5.

[0070] In the soil erosion prevention structure 10 of this embodiment, another sandbag stack (i.e., add-on sandbag stack 80) covered with the mesh body 30 is further placed on top of the sandbag stack 20 covered by the sandbag covering area 36 of the mesh body 30.

[0071] In addition, in the present embodiment, the sandbag 22 that constitutes the sandbag laminate 20 has a water-permeable bag body 24, and the filling material 26 filled in the bag body 24 contains earth and sand and cement as a hardening material. When water contained in the outflowing earth and sand penetrates into the bag body 24, the sandbag 22 containing cement hardens, making the sandbag laminate 20 less likely to collapse. Thus, when the filling material 26 of the sandbag 22 contains a hardening material, it is preferable to provide a water pipe 48 in order to ensure the water permeability after the sandbag hardens.

[0072] The retrofitted sandbag laminate 80 is installed after the outflowing earth and sand is blocked by the sandbag laminate 20, and is installed above the existing sandbag laminate 20 via the sandbag covering region 36 of the net body 30. The retrofitted sandbag laminate 80 is formed by stacking a plurality of sandbags 22 in a wall shape. The retrofitted sandbag laminate 80 of the present embodiment is formed by stacking a plurality of sandbags 22 above the sandbag laminate 20 and the deposited earth and sand 70 blocked by the sandbag laminate 20. In this way, by placing the sandbag 22 on the deposited earth and sand 70, it is possible to prevent the deposited earth and sand 70 from collapsing and increase the strength of the entire earth and sand outflow prevention structure 10.

[0073] The sandbag 22 used for the upper sandbag laminate 80 of the retrofitted sandbag laminate may be the same as the sandbag 22 used for the existing sandbag laminate 20, or the bag body 24 and the filling material 26 may be changed to different ones.

[0074] Although not shown in the drawings, a water pipe 48 penetrating from the slope mountain side to the slope valley side may be provided in the retrofitted sandbag laminate 80. Thereby, the moisture contained in the earth and sand blocked by the retrofitted sandbag laminate 80 can be discharged to the slope valley side of the retrofitted sandbag laminate 80.

[0075] In this embodiment, the net body 30 has an additional sandbag covering region 38 that covers the outer surface of the post-installation sandbag stack 80. The additional sandbag covering region 38 is a region that extends from the sandbag covering region 36 to the upper side of the slope S, covering the outer surface of the post-installation sandbag stack 80 and the outer surface of the accumulated soil 70. In this embodiment, the mountain side end 38b of the additional sandbag covering region 38 is fixed to the slope S using a fastener 40 in a state where it is overlapped with the mountain side region 32. This additional sandbag covering region 38 can be attached to the sandbag covering region 36 of the net body 30 using a linear material such as wire. Note that, when the accumulated soil 70 is accumulated up to the slope mountain side beyond the mountain side region 32 of the net body 30, the additional sandbag covering region 38 may be extended up to the slope mountain side beyond the mountain side region 32, and fixed to the slope S without overlapping the mountain side region 32.

[0076] In addition, additional mesh portions 60-3, 60-4 are installed between each tier of sandbags 22 that make up the retrofit sandbag stack 80, thereby integrating each tier of sandbags 22 and, since each additional mesh portion 60-3, 60-4 is connected to the additional sandbag covering area portion 38, the multiple tiers of sandbags 22 are integrated together.

[0077] The above-mentioned retrofit sandbag stack 80, additional mesh portions 60-3, 60-4 and additional sandbag covering area 38 can be constructed in the same manner as the previously described sandbag stack 20, additional mesh portions 60-1, 60-2 and sandbag covering area 36.

[0078] In the sediment outflow prevention structure 10 of this embodiment, after the sediment flow occurring on the slope S is dammed by the sandbag stack 20, the dammed sediment 70 is used to stack a plurality of sandbags 22 on top of the sediment 70 and the existing sandbag stack 20 to provide a post-installation sandbag stack 80, thereby damming up more sediment. In addition, since the post-installation sandbag stack 80 is integrated with the sandbag stack 20 in a state where the outer surface is covered by the additional sandbag covering area 38 of the net body 30, the fixing force to the slope S is high, and the entire wall-like structure (i.e., the entire sandbag stack 20, the post-installation sandbag stack 80, the sediment 70 integrated with them, and the net body 30 that integrates them) is unlikely to collapse. This allows the sediment flow that occurs thereafter to be appropriately dammed.

[0079] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention.

[0080] For example, in the above-mentioned retrofit sandbag stack 80, a water pipe 48 may be provided that penetrates from the mountain slope to the valley slope, similar to the lower sandbag stack 20. Also, after the runoff sand is blocked by the retrofit sandbag stack 80, another retrofit sandbag stack (i.e., a second retrofit sandbag stack) covered with the blocked sand and net body 30 may be installed on the first retrofit sandbag stack 80. In this way, the sandbag stack placed on the sandbag placement area 32 of the net body 30 can be integrated with the existing sandbag stack by stacking additional sandbags 22 each time the amount of runoff sand increases, using the net body 30. [Explanation of symbols]

[0081] 10. Soil runoff prevention structure 20 Sandbag stack 22 Sandbags 24 Bag body 26 Filling material 30 net body 32 Mountain side area 34 Sandbag placement area 36 Sandbag Covered Area 37 Earth cover area 38 Additional sandbag covered area 60 Additional Net Body 80 Retrofit sandbag stack S Ground slope

Claims

1. A structure for preventing soil erosion comprises a sandbag stack in which sandbags are stacked vertically on a slope in a number of stages, and a net body fixed to the slope while covering the outer surface of the sandbag stack, the net body preventing soil erosion from the slope by the sandbag stack, The soil and sand flowing out from a slope above the sandbag stack due to a collapse of a ground slope and being blocked by the sandbag stack, The mesh body is A sandbag placement area is laid on the slope and has the sandbag stack placed on its upper surface; a mountain side area portion that is extended to the slope mountain side of the sandbag placement area and has an end portion on the mountain side of the slope fixed to the slope with the accumulated soil and sand present on its upper surface; A sandbag covering area is provided on the slope valley side of the sandbag placement area, folded back so as to cover at least the upper surface of the stack of sandbags placed on the slope valley side, and fixed to the mountain side area. a soil covering area portion having an end portion on the slope valley side connected to the sandbag covering area portion and covering the outer surface of the accumulated soil, and an end portion on the slope mountain side fixed to a position above the area where the accumulated soil is present on the slope; A structure for preventing soil erosion, comprising:

2. 2. The structure for preventing soil erosion according to claim 1, wherein the sandbag placing area, the mountain side area and the sandbag covering area of ​​the mesh body are formed from a single mesh member.

3. 2. The structure for preventing soil erosion according to claim 1, wherein the sandbag placing area, the mountain side area and the sandbag covering area of ​​the mesh body are formed by connecting a plurality of mesh members.

4. 4. The structure for preventing soil erosion according to claim 1, further comprising a water pipe extending through the stack of sandbags from the mountain side of the slope to the valley side of the slope.

5. The sandbag comprises a bag body and a filling material enclosed inside the bag body, The bag body has water permeability, 5. The structure for preventing soil erosion according to claim 1, wherein the filling material is composed of granular material having an average grain size of 3 mm to 15 mm.

6. The sandbag comprises a bag body and a filling material enclosed inside the bag body, The bag body has water permeability, 5. The structure for preventing soil erosion according to claim 1, wherein the filling material contains a hardening material that hardens in response to moisture.

7. A soil erosion prevention structure as described in any one of claims 1 to 6, characterized in that the mesh body has an additional mesh body portion that is laid between the top and bottom of the sandbags that are stacked vertically, covers the bottom and top of the sandbags, and is connected to the sandbag covering area portion of the mesh body.

8. A post-installation sandbag stack is provided in which a plurality of sandbags are stacked in a wall shape above the sandbag stack and the accumulated soil blocked by the sandbag stack, A soil erosion prevention structure as described in any one of claims 1 to 7, characterized in that the mesh body has an additional sandbag covering area that covers the outer surface of the retrofit sandbag stack from the sandbag covering area and is fixed to the mountain side area.

9. A construction method for constructing the soil outflow prevention structure according to any one of claims 1 to 8, laying the net on the slope; A step of piling up a plurality of sandbags on the upper surface of the lower slope area of ​​the laid net body to form the sandbag stack, and forming the sandbag placement area and the mountain side area of ​​the net body; a step of extending the net from the end of the sandbag placement area on the slope valley side to cover the outer surface of the sandbag stack and connect to the mountain side area to form the sandbag covering area of ​​the net; After the accumulated soil is placed in the mountain side area, the net is extended from the sandbag placement area to cover the outer surface of the sandbag stack, forming the soil covering area of ​​the net; A construction method comprising:

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