Flow rate reducing bag, mat, and protection method of slope soil

Abstract

To provide a flow rate reducing bag that improves workability, reduces a flow rate of running water, and simultaneously retains moisture in slope soil.SOLUTION: A flow rate reducing bag 100 comprises: a bag body 110 having a bottom wall portion 111 arranged on a ground side and a top wall portion 112 arranged above the opposite side of the ground and extending in a longitudinal direction; and a filling material 120 filled into the bag body 110 and including granular material of a predetermined grain size or particle diameter. When placed on slope soil, the flow rate reducing bag 100 is formed into a long cylindrical shape extending in a direction perpendicular to an inclination direction of the slope soil, and is configured to form a dam having a predetermined height vertically from a surface of the slope soil. The top wall portion 112 includes a water-impermeable region 114 that is water-impermeable, and a portion of the bag body 110 other than the water-impermeable region 114 includes a water-permeable region 113 that is water-permeable.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flow velocity reduction bag that is placed on sloping soil to reduce the flow velocity of running water flowing over the surface of the sloping soil, a mat equipped with the flow velocity reduction bag, and a method for protecting sloping soil using the flow velocity reduction bag. [Background technology]

[0002] In recent years, intermittent rainfall and torrential rains have caused erosion of the soil surface on slopes, resulting in disasters such as landslides. In order to reduce or prevent soil erosion on slopes, various measures have been implemented.

[0003] Patent Document 1 discloses a log structure that uses logs to prevent the runoff of surface soil on a slope. In the following paragraphs, the reference number of Patent Document 1 is shown in parentheses. The log structure (1) is installed on a slope as a log brace, and is formed to prevent the runoff of surface soil and protect vegetation. The main part of the structure is composed of logs (11) arranged in a substantially horizontal direction on the ground (15) of the slope, a plurality of upper stacked logs (12) stacked on the logs, a fully threaded steel bar (13) that penetrates the logs (11) and the upper stacked logs (12) in the vertical direction and penetrates into the ground, and a nut (14) that is twisted to the top of the fully threaded steel bar (13) and tightened on the uppermost upper stacked log (12). Such log brace works are generally constructed to dam surface water flowing down a slope and to increase the flow velocity reduction effect and rainwater dispersion effect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-25314 Summary of the Invention [Problem to be solved by the invention]

[0005] In mountainous areas, log reinforcing bars as described in Patent Document 1 can be installed on slopes to reduce the flow rate of surface water. However, one of the problems with constructing log reinforcing bars on slope soil is that the logs are heavy and require a lot of time and effort from workers. In addition, while it is common to simultaneously reduce the flow rate of running water and green the slope soil, log reinforcing bars cannot prevent the slope soil from drying out, and other work for greening is required in addition to the log reinforcing bars, which means that the slope soil cannot be efficiently moisturized.

[0006] The present invention has been made to solve the above-mentioned problems, and its object is to provide a flow rate reduction bag that improves workability and reduces the flow rate of running water while simultaneously retaining moisture in slope soil, a mat equipped with said flow rate reduction bag, and a method of protecting slope soil using said flow rate reduction bag. [Means for solving the problem]

[0007] A flow velocity reduction bag according to one embodiment of the present invention is a flow velocity reduction bag that is installed on a slope soil and reduces the flow velocity of running water flowing on the surface of the slope soil, A bag body extending in a longitudinal direction, the bag body having a bottom wall portion disposed on the ground side and a top wall portion disposed above the opposite side of the ground; A filler material containing granular material of a predetermined particle size or particle diameter filled in the bag; Equipped with the flow velocity reduction bag is formed in an elongated cylindrical shape extending in a direction perpendicular to the inclination direction of the slope soil when placed on the slope soil, and is configured to form a weir having a predetermined height in a vertical direction from the surface of the slope soil, The top wall portion includes a water-impermeable region that is water-impermeable, and a portion of the bag body other than the water-impermeable region includes a water-permeable region that is water-permeable.

[0008] The flow velocity reducing bag according to one embodiment of the present invention, when installed on a slope, is a long cylinder extending in a direction perpendicular to the slope direction of the slope soil, and forms a weir having a predetermined height vertically from the surface of the slope soil, thereby enabling the effect of reducing the flow velocity of surface water (or running water) flowing on the slope soil surface. In addition, since the flow velocity reducing bag is composed of a bag body and a filler material containing granular material filled in the bag body, it has a higher ability to follow the unevenness of the slope soil compared to the log material used in log reinforcement work, and is easier to handle, thereby achieving improved workability. Furthermore, the top wall of the bag body includes a water-shielding region, and the part of the bag body other than the water-shielding region includes a water-permeable region. As a result, when it rains, the surface water flowing on the slope soil passes through the inside of the bag body through the water-permeable region and is drained from the downstream side. In other words, when the surface water passes through the filler material, the flow velocity of the surface water is effectively reduced. Even when there is no surface water when it is not raining (for example, on a sunny day) after rainwater has been absorbed into the flow velocity reduction bags, the water shielding area covers the filler from above, reducing the amount of moisture stored in the filler that evaporates into the air. This allows the flow velocity reduction bags to maintain a state in which they can supply moisture to the slope soil for a longer period of time, thereby moisturizing the slope soil and promoting its greening.

[0009] A further embodiment of the flow-reducing bag of the present invention is characterized in that, in the flow-reducing bag of the above embodiment, the filler contains granular material having a grain size or particle diameter of at least 10 mm or less. That is, by using granular material having a grain size or particle diameter of 10 mm or less as the filler, the granular material densely fills gaps inside the bag and can move relatively freely inside the bag, making it possible to easily change the outer shape of the flow-reducing material to suit the installation environment.

[0010] A further embodiment of the flow velocity reducing bag of the present invention is characterized in that, in the above-mentioned embodiment, the filler is made of wood chips, wood flour, or a combination thereof. The flow velocity reducing material can be easily prepared by filling the bag with wood chips or wood flour, and is relatively lighter than logs, so that it can be more easily installed.

[0011] A further embodiment of the flow-velocity reducing bag of the present invention is characterized in that, in the above-described embodiment, the bag further comprises a synthetic resin mesh surrounding the outer surface of the bag. By surrounding the outer surface of the bag with the synthetic resin mesh, the bag can be effectively reinforced without preventing the flow of water from entering the bag.

[0012] A further embodiment of the flow velocity reducing bag of the present invention is characterized in that, in the flow velocity reducing bag of the above embodiment, the height of the dam is 5 to 13 cm in the vertical direction from the surface of the slope soil. That is, by forming a dam of an appropriate height on the surface of the slope soil, it is possible to effectively reduce the flow velocity of surface water without impeding workability.

[0013] The mat of one embodiment of the present invention includes a flexible mat body extending lengthwise and widthwise, the lengthwise direction of which is arranged along the slope direction of the slope soil; and one or more flow velocity reducing bags according to any one of claims 1 to 5, which are attached to the surface of the mat body and are used to reduce the flow velocity of running water flowing on the surface of the slope soil; The one or more flow-velocity reducing bags are held in the mat body so that the longitudinal direction of each of the flow-velocity reducing bags is aligned with the lateral direction.

[0014] The mat of one embodiment of the present invention makes it possible to exert the effect of the flow velocity reduction bag as a mat. By placing the mat body holding the flow velocity reduction bag on the slope soil, it is possible to easily construct a protection structure for the slope soil.

[0015] One form of a method of the present invention is a method for protecting sloping soil, characterized in that it includes a step of fixing one or more flow velocity reduction bags to the sloping soil via fixing members so that the longitudinal direction of the flow velocity reduction bags is aligned perpendicular to the slope direction of the sloping soil. Effect of the Invention

[0016] The flow velocity reducing bag of the present invention exhibits good workability and is capable of reducing the flow velocity of running water while at the same time retaining moisture in the slope soil. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic perspective view of a flow rate reduction bag according to one embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view of the flow velocity reduction bag of FIG. 1. [Diagram 3] FIG. 2 is a schematic perspective view of a mat equipped with the flow velocity reduction bag of FIG. 1. [Figure 4] 1 is a schematic perspective view of an overall slope soil protection structure using flow velocity reduction bags and mats according to one embodiment of the present invention; [Diagram 5] FIG. 5 is a longitudinal cross-sectional view showing the configuration of the slope soil protection structure of FIG. 4 during rainfall. [Figure 6] 5 is a longitudinal cross-sectional view showing the configuration of the slope soil protection structure of FIG. 4 when it is not raining after the flow velocity reduction bag has absorbed water due to rainfall. FIG. [Figure 7] 6 is a graph showing the moisture retention of slope soil in the flow velocity reduction bag of the present embodiment. [Figure 8] FIG. 4 is a schematic cross-sectional view showing a modified example of the mat of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the shapes of the figures referred to in the following description are conceptual or schematic diagrams for explaining preferred shapes and dimensions, and the dimensional ratios do not necessarily match the actual dimensional ratios. In other words, the present invention is not limited to the dimensional ratios in the drawings.

[0019] The flow velocity reduction bag 100 of one embodiment of the present invention is installed along the contour line direction of a sloping soil such as a slope, thereby reducing the flow velocity of surface water during rainfall and preventing erosion of the soil surface. In this specification, when one or more flow velocity reduction bags 100 are installed on sloping soil, the direction along the inclination direction of the slope is defined as the "vertical" direction, and the direction along the contour line direction of the slope is defined as the "horizontal" direction. Furthermore, when the flow velocity reduction bag 100 is installed on sloping soil, the side that is located on the toe side (upper or higher side) is defined as the "upper" position, and the side that is located on the toe side (lower or lower side) is defined as the "lower" position.

[0020] Fig. 1 is a schematic perspective view of a flow reduction bag 100 according to one embodiment of the present invention. Fig. 2 is a cross-sectional view of the flow reduction bag 100.

[0021] As shown in Figs. 1 and 2, the flow velocity reduction bag 100 is installed on the surface of the slope soil so as to reduce the flow velocity of running water (surface water) flowing on the surface of the slope soil. In this embodiment, the flow velocity reduction bag 100 is attached to the surface of the mat body 11 of the mat 10 laid on the slope soil. When installed on the slope soil, the flow velocity reduction bag 100 is formed in an elongated cylindrical shape extending in a direction perpendicular to the inclination direction of the slope soil (lateral direction) and is configured to form a dam having a predetermined height vertically from the surface of the slope soil. The flow velocity reduction bag 100 preferably protrudes vertically from the surface of the slope soil (or the mat body 11) to a height of 5 to 13 cm so as to function as a dam. More specifically, the flow velocity reduction bag 100 of this embodiment preferably has a circular or elliptical shape in the cross-sectional view shown in Fig. 2 and has a circumference of about 25 to 40 cm. If the flow velocity reduction bag 100 is smaller than the above-mentioned size, the flow velocity reduction effect will be small, and conversely, if it is larger than the above-mentioned size, workability will be poor.

[0022] 2, the flow velocity reducing bag 100 comprises a bag body 110, a filler material 120 filled in the bag body 110, and a mesh body 130 surrounding the outer surface of the bag body 110. Unlike logs and the like, the flow velocity reducing bag 100 can change its outer shape to some extent by moving the filler material 120 inside the bag body 110. In other words, the flow velocity reducing bag 100 can change its shape to fit the unevenness and undulations of the slope soil on which it is installed.

[0023] The bag body 110 has a bottom wall 111 arranged on the ground side, and a top wall 112 arranged on the opposite side of the ground. The bottom wall 111 and the top wall 112 are rectangular flexible sheets extending in the longitudinal direction. Both ends of the sheets in the width direction (perpendicular to the longitudinal direction) and both ends of the sheets in the longitudinal direction are joined (for example, by sewing, welding, or bonding) to form a long tube shape (or bag shape) capable of holding the filler 120 inside. The top wall 112 includes a water-blocking region 114 having water-blocking properties, and the portion of the bag body 110 other than the water-blocking region 114 is made of a water-permeable region 113 having water permeability. The bag body 110 is made of a material capable of holding the granular filler 120 inside so as not to flow out of the bag body 110 as a whole.

[0024] In this embodiment, the bottom wall 111 and the water-permeable region 113 are formed from a water-permeable sheet that can hold the particulate filler 120 inside the bag 110 and has water permeability (allowing moisture to pass through). In this embodiment, the entire bottom wall 111 forms the water-permeable region 113. For example, the water-permeable sheet may be selected from nonwoven fabric, woven fabric, etc. (without limiting the present invention). More specifically, the material of the nonwoven fabric and woven fabric may be selected from polyester, polyethylene, polypropylene, nylon, polylactic acid, rayon, cotton, a mixture thereof, etc.

[0025] In this embodiment, the top wall 112 is formed of a waterproof sheet that can hold the particulate filler 120 inside the bag body 110 and has water impermeability (blocking the passage of moisture). In this embodiment, the entire top wall 112 forms the waterproof region 114. For example, the waterproof sheet may be selected from paper, a resin sheet (e.g., polyvinyl chloride, polyolefin, polyethylene sheet, etc.), a foamed resin sheet, or a combination thereof (without limiting the present invention). The waterproof sheet is preferably transparent or semi-transparent so that the contents can be seen. The waterproof region 114 may also have thermal insulation properties. When a foamed polyethylene sheet by closed-cell molding with thermal insulation properties is selected as the material for the waterproof sheet, the thickness of the foamed polyethylene sheet is preferably about 0.5 mm or more in order to exhibit a predetermined thermal insulation property.

[0026] The filler 120 is composed of granular materials of a predetermined grain size or particle diameter, excluding vegetative materials. The vegetative materials include at least one of seeds, fertilizers, soil improvement materials, water retention materials, water repellency suppression materials, and growth base materials. In this embodiment, the filler 120 is composed to include at least one of wood chips and wood flour. Wood chips and wood flour are easily and economically available from thinned wood and waste wood. Wood chips are generally randomly shaped, but are preferably granular materials (small pieces, fragments) having a grain size or particle diameter of about 10 mm or less. Wood flour is preferably shavings that are finer than wood chips. However, the filler 120 may include granular materials such as crushed urethane, waste paper, resin pieces, and gravel in addition to the wood chips or wood flour. Alternatively, the filler 120 may include granular materials such as crushed urethane, waste paper, resin pieces, and gravel instead of wood chips. That is, the filler 120 may be selected from any material capable of reducing the flow rate. The granular material preferably has a grain size or particle diameter of 10 mm or less, and is a material or size that can be stably maintained inside the bag body 110 without dissolving in water. If the granular material is 10 mm or less, it densely fills the gaps inside the bag body 110 and can move relatively freely inside the bag body 110, so that the outer shape of the filler 120 can be easily deformed to match the installation environment. Furthermore, the filler 120 may include lumps such as wood chips having a grain size or particle diameter larger than the granular material having a grain size or particle diameter of 10 mm or less.

[0027] The mesh body 130 is composed of a tubular synthetic resin net that covers the entire outer surface of the bag body 110. This synthetic resin net is integrally molded from flexible and elastic synthetic resin. For example, the mesh body 130 can be molded using polyethylene as the main raw material. Since such a synthetic resin net is formed as a so-called "non-woven net" integrally molded from synthetic resin, it has higher strength and durability than a net formed by weaving wires.

[0028] 3 is a schematic perspective view of the mat 10 equipped with a plurality of flow-reducing bags 100. The mat 10 includes a flexible mat body 11 extending lengthwise and widthwise with its lengthwise direction aligned with the inclination direction of the sloping soil, and a plurality of flow-reducing bags 100 attached to the surface of the mat body 11 for reducing the flow rate of running water flowing on the surface of the sloping soil. When the mat 10 is installed on the sloping soil, each flow-reducing bag 100 is held by the mat body so that the longitudinal direction of each flow-reducing bag 100 is aligned with the lateral direction.

[0029] The mat body 11 is a flexible sheet that extends lengthwise and widthwise to cover the protected area of ​​the slope soil and protect the slope soil. The mat body 11 is configured so that, due to its flexibility or pliability, it can adhere closely to the surface of the slope soil having unevenness or undulations when laid. In this embodiment, the mat body 11 is composed of a mesh sheet 12 and a seeded sheet 13 attached to the back side of the mesh sheet 12. In this embodiment, the mesh sheet 12 is formed by weaving synthetic resin fibers or natural fibers lengthwise and widthwise with a predetermined mesh size. The seeded sheet 13 is a nonwoven sheet with plant seeds scattered on its surface.

[0030] The flow rate reduction bags 100 are attached to the surface of the mat body 11 so as to reduce the flow rate of the flowing water (surface water) flowing on the surface of the slope soil. The flow rate reduction bags 100 can be connected to the surface of the mat body 11 in whole or in part by using any attachment means such as a C-ring, staple, adhesive, etc. In this embodiment, the flow rate reduction bags 100 are arranged at intervals in the vertical direction on one mat body 11. This interval is preferably about 0.5 to 5 m. The flow rate reduction bags 100 extend across the entire width of the mat body 11. In this embodiment, the flow rate reduction bags 100 are attached to one mat body 11 that is long in the vertical direction, but one flow rate reduction bag 100 may be attached to one mat body 11. Also, the flow rate reduction bags 100 may be attached continuously in the horizontal direction to one mat body 11.

[0031] Next, a slope soil protection structure in which a plurality of flow velocity reducing bags 100 of this embodiment are installed in a predetermined protection area of ​​the slope soil G will be described with reference to Fig. 4 to Fig. 6. Fig. 4 is a schematic perspective view of the slope soil protection structure. Fig. 5 is a schematic cross-sectional view of the slope soil protection structure during rainfall, and Fig. 6 is a schematic cross-sectional view of the slope soil protection structure during fine weather.

[0032] As shown in FIG. 4, in the slope soil protection structure, a plurality of mats 10 are installed on the slope soil G so that the longitudinal direction of each mat 10 is along the inclination direction of the slope soil G. Each mat 10 and the flow velocity reduction bag 100 are fixed to the slope soil G by a plurality of anchor pins 15 as fixing members. The anchor pins 15 are driven so as to penetrate the flow velocity reduction bag 100 and the mat body 11. By penetrating the flow velocity reduction bag 100 and the mat body 11, the anchor pins 15 can become a connecting part that connects the flow velocity reduction bag 100 and the mat body 11. In addition, in the slope soil protection structure of this embodiment, the slope soil G is covered by the plurality of mats 10 so that it is not exposed. Then, in the mats 10 adjacent to each other in the contour line direction, the plurality of flow velocity reduction bags 100 are continuously arranged in the contour line direction of the slope soil G. In other words, the plurality of flow velocity reduction bags 100 are arranged without interruption in the contour line direction, so that the flow velocity reduction effect is exerted in the entire protected area of ​​the slope soil G.

[0033] FIG. 5 shows a schematic cross section of the slope soil protection structure during rainfall. As shown in FIG. 5, the mat body 11 is grounded on the surface of the slope soil G, and the flow rate reduction bag 100 attached to the surface of the mat body 11 forms a dam with a predetermined height in the vertical direction from the surface of the mat body 11. Here, in FIG. 5, the surface water flowing on the slope soil G is indicated by arrows. As shown in FIG. 5, when surface water is generated by rainfall or the like, the flow rate reduction bag 100 functions to dam the water on the upper side in the inclination direction. The flow rate reduction bag 100 restricts the surface water from passing at its original flow rate. That is, a part of the surface water passes through the inside of the flow rate reduction bag 100, and a part of the surface water accumulates on the upper side of the inclination direction of the flow rate reduction bag 100, and flows down the inclination direction below the top of the flow rate reduction bag 100. In this way, the surface water is dispersed by the flow rate reduction bag 100, and the flow rate is effectively reduced.

[0034] As shown in FIG. 5, when it rains, the filler 120 absorbs running water through the water permeable region 113 of the bag body 110. FIG. 6 shows a schematic cross section of the slope soil protection structure when it is not raining after the flow rate reduction bag absorbs water due to rain. As shown in FIG. 6, in the flow rate reduction bag 100 of this embodiment, the water shielding region 114 extends to cover the absorbed filler 120 from above, so that evaporated water (water vapor) does not pass through the top wall portion 112 and remains inside the bag body 110. In particular, since water vapor is lighter than air, it is considered that it does not actively flow out through the water permeable region 113 formed in the lower half of the bag body 110. As a result, the amount of evaporation of water absorbed in the flow rate reduction bag 100 decreases. Then, the water stored in the flow rate reduction bag 100 is gradually supplied to the slope soil G, and the slope soil G can be effectively moisturized. As a result, the greening of the slope soil G can be effectively promoted.

[0035] In the above embodiment, the entire top wall 112 forms the water-shielding region 114, which extends to cover the entire filler 120 from above, but the present invention is not limited to this. In other words, if the water-shielding region extends to cover a part of the filler from above, it is possible to relatively improve the water retention of the flow rate reduction bag. Preferably, if the water-shielding region is formed over about 60% or more of the surface area of ​​the top wall, it is possible to sufficiently reduce the amount of water that evaporates.

[0036] Next, a method for constructing a slope soil protection structure by installing a plurality of flow velocity reduction bags 100 and mats 10 on the slope soil G will be described. First, a predetermined number of mats 10 are prepared according to the area of ​​a predetermined protection area. A plurality of mats 10 are installed on the slope soil G so that the longitudinal direction of the mats 10 is along the inclination direction of the slope soil G. The flow velocity reduction bags 100 of the mats 10 adjacent in the horizontal direction are aligned so as to be continuous at the same level without interruption in the contour line direction of the slope soil G. Then, each mat 10 is fixed to the slope soil G together with the plurality of flow velocity reduction bags 100 by driving anchor pins 15 as fixing members. That is, according to this method, a slope soil protection structure having a surface water flow velocity reduction effect and a sediment runoff reduction effect can be constructed by aligning and installing a plurality of flow velocity reduction bags 100 on the slope soil G, and the slope soil G can be protected more easily and efficiently than the conventional log brace construction method.

[0037] The inventors conducted a demonstration test to confirm the effect of the flow velocity reduction bag of the present invention described above. In the demonstration test, soil was formed to a depth of 6 cm on a tray inclined at about 45 degrees so as to simulate an environment similar to that of actual slope soil (e.g., a slope), and the change in moisture in the soil over time was measured. The soil moisture was measured at a depth of 0.5 cm from the soil surface and at the position of the lower edge of the flow velocity reduction bag using a soil moisture sensor EC-5 manufactured by Meter Japan Co., Ltd. The soil moisture is expressed as a volumetric water content. Since the dielectric constant of soil is proportional to the soil moisture content, the volumetric water content in the soil can be obtained by measuring the dielectric constant of the soil. This demonstration test was conducted outdoors for one month from mid-April to mid-May in a completely private site where outside access is prohibited.

[0038] In the demonstration test, the examples were formed in the same configuration as the flow velocity reduction bag 100 of the above embodiment, with the top wall of the bag being formed from a water-impermeable polyvinyl chloride sheet and the bottom wall being formed from a water-permeable nonwoven fabric. In the comparative example, the entire bag was formed from a water-permeable nonwoven fabric. In both the examples and the comparative example, the filler was wood powder. In other words, the difference between the examples and the comparative example was whether or not a water-impermeable area was provided.

[0039] FIG. 7 is a graph showing the change in volumetric water content in the slope soil over a one-month period as a result of the demonstration test. The volumetric water content of the example and the comparative example temporarily increases at the timing of rainfall, and then gradually decreases when there is no rainfall. For example, when looking at the change in volumetric water content from 16 days after rainfall to 17 days after rainfall, it can be seen that the example loses about 13% of water, from 0.45 to 0.39, while the comparative example loses about 21% of water, from 0.38 to 0.30. That is, the example shows an improvement in the water loss rate after rainfall compared to the comparative example. Also, the volumetric water content (0.27) after 18 days (2 days after rainfall) of the comparative example is almost the same as the volumetric water content (0.27) after 21 days (5 days after rainfall) of the example. The example can maintain the amount of water for 2 to 3 days more than the comparative example.

[0040] In light of the above, the effects of the flow velocity reduction bag 100 according to one embodiment of the present invention will be described.

[0041] According to the flow velocity reduction bag 100 of this embodiment, when the flow velocity reduction bag 100 is installed on the slope soil G, it forms a weir having a predetermined height in the vertical direction from the surface of the slope soil G as a long cylinder extending in a direction perpendicular to the inclination direction of the slope soil G, and can reduce the flow velocity of the surface water. In addition, since the flow velocity reduction bag 100 is composed of a bag body 110 and a filler material 120 containing granular material filled in the bag body 110, it has a higher ability to follow the unevenness of the slope soil G than the log material used in log reinforcement work, and is easier to handle, thereby improving workability. Furthermore, the top wall portion 112 of the bag body 110 includes a water-shielding region 114, and the part of the bag body 110 other than the water-shielding region 114 includes a water-permeable region 113. As a result, when it rains, the surface water flowing on the slope soil G passes through the inside of the bag body 110 through the water-permeable region 113 and is drained from the downstream side. That is, the flow rate of the surface water is effectively reduced when the surface water passes through the filler 120. Even in a non-rainfall state (e.g., on a sunny day) in which there is no surface water after rainfall has absorbed water into the flow rate reduction bag 100, the water-shielding region 114 covers the filler 120 from above, thereby reducing the amount of moisture stored in the filler 120 that evaporates into the air. This allows the flow rate reduction bag 100 to maintain a state in which it can supply moisture to the slope soil G for a longer period of time, thereby moisturizing the slope soil G and promoting its greening.

[0042] [Variations] The present invention is not limited to the above-described embodiment, and various modifications are possible. Modifications of the present invention will be described below.

[0043] (1) In the above embodiment, the flow velocity reduction bag is attached to the mat, but the present invention is not limited to this. For example, the flow velocity reduction bag may be directly installed on the slope soil so that the longitudinal direction of the flow velocity reduction bag is aligned perpendicular to the slope direction of the slope soil.

[0044] (2) The mat of the present invention is not limited to the above embodiment and may take various forms. As shown in FIG. 8, the mat 10' and the mat body 11' may be provided with one or more vegetation bags 14 as greening materials between vertically adjacent flow velocity reduction bags 100. The vegetation bag 14 is a longitudinal bag containing vegetative materials. The vegetative materials include at least one of seeds, fertilizer, soil improvement materials, water retention materials, water repellency suppression materials, and growth base materials. Meanwhile, the mesh sheet 12 has a plurality of locations where the mesh body is doubled, and a plurality of storage sections 12a extending in a long cylindrical shape in the horizontal direction are provided at the locations. The storage section 12a is made of a long cylindrical mesh body and is configured to be able to hold the vegetation bag 14.

[0045] (3) The mat of the present invention is not limited to the above embodiment and may take various forms. In the above embodiment, the mat body is a laminate of a mesh sheet and a seed-bearing sheet, but may be selected arbitrarily. For example, the mat body may be a cotton-like sheet, a nonwoven fabric, a urethane sheet, or the like of a predetermined thickness.

[0046] (4) The flow-velocity reducing bag of the present invention is not limited to the above embodiment, and may take various forms. In the above embodiment, the flow-velocity reducing material is formed as an integral elongated cylinder, but the present invention is not limited to this. For example, the flow-velocity reducing material may be composed of an assembly of multiple bags connected in the horizontal direction.

[0047] It should be noted that the present invention is not limited to the above-described embodiments, but may be embodied in various forms within the technical scope of the present invention. [Explanation of symbols]

[0048] 10. Matt 11 Mat body 12 Mesh Sheet 12a Storage section 13 Seed-bearing sheet (greening material) 14 Vegetation bags (greening materials) 15 Anchor pin (fixing member) 100 Flow velocity reduction bag 110 Bag body 111 Bottom wall 112 Top wall 113 Permeable area 114 Water-impermeable area 120 Filling material 130 Reticulum G. Slope soil

Claims

1. A flow velocity reduction bag that is installed on a slope of soil and reduces the flow velocity of running water flowing on the surface of the slope of soil, A bag body extending in a longitudinal direction, the bag body having a bottom wall portion disposed on the ground side and a top wall portion disposed above the opposite side of the ground; A filler material containing granular material of a predetermined particle size or particle diameter filled in the bag; Equipped with the flow velocity reduction bag is formed in an elongated cylindrical shape extending in a direction perpendicular to the inclination direction of the slope soil when placed on the slope soil, and is configured to form a weir having a predetermined height in a vertical direction from the surface of the slope soil, A flow velocity reducing bag, characterized in that the top wall portion includes a water-impermeable area having water impermeability, and a portion of the bag body other than the water-impermeable area includes a water-permeable area having water permeability.

2. 2. The flow velocity reduction bag of claim 1, wherein the filler material includes granules having a particle size or diameter of at least 10 mm or less.

3. 3. The flow reduction bag of claim 2, wherein the filler material comprises wood chips, wood flour, or a combination thereof.

4. 4. The flow velocity reducing bag according to claim 3, further comprising a synthetic resin mesh surrounding the outer surface of the bag.

5. 5. The flow velocity reducing bag according to claim 4, wherein the height of the weir is 5 to 13 cm in the vertical direction from the surface of the slope soil.

6. A flexible mat body extending lengthwise and widthwise, the lengthwise direction being arranged along the slope direction of the slope soil; and one or more flow velocity reducing bags according to any one of claims 1 to 5, which are attached to the surface of the mat body and serve to reduce the flow velocity of running water flowing on the surface of the slope soil; A mat, characterized in that each of the one or more flow-velocity reducing bags is held in the mat body so that the longitudinal direction of the flow-velocity reducing bag is aligned with the lateral direction.

7. The mat according to claim 6, further comprising a greening material attached to the mat body.

8. A method for protecting slope soil, comprising the step of fixing one or more flow velocity reduction bags described in any one of claims 1 to 5 to the slope soil via fixing members so that the longitudinal direction of the flow velocity reduction bags is aligned perpendicular to the slope direction of the slope soil.

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