JP2963987B2 - Greenable erosion protection sheet / mat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet mat for preventing erosion while greening a slope.

[0002]

2. Description of the Related Art Conventionally, as this kind of sheet mat, there is one disclosed in Japanese Patent Application Laid-Open No. 6-10324, in which a nonwoven fabric layer having a fiber density of 10 to 2000 m / cm ³ is provided on dike soil. A plant is vegetated thereon, and the roots of the plant penetrate the nonwoven fabric layer and are laid inside the embankment.

In this type of sheet mat, there are demands for (1) a function for preventing turning up and (2) a function for preventing suction. These (1) roll-up prevention functions mean that plants exposed to running water are less likely to be washed away, and at the same time, sheet mats are connected to the ground by plant roots, making it more difficult for them to turn up. (2) The function of preventing suction is a function of making the void diameter of the nonwoven fabric smaller than the diameter of earth and sand so as to prevent earth and sand from passing through the nonwoven fabric.

[0004]

Considering the functions disclosed in the above-mentioned gazettes, it is found that the nonwoven fabric has a fiber density of 10 to 2000 m / cm ³ , 5 mm thick (Examples 1 and 2),
8 mm (Comparative Example 1), 10 mm (Example 3), 1.1 mm (Example 4), and 0.1 mm (Comparative Example 4). And it is said that such a thing uses the voids of the nonwoven fabric to prevent vegetation from turning up by vegetation, but in order to do so, it is necessary to reduce the fiber density of the nonwoven fabric and increase the pore size, Doing so will reduce the suction prevention effect,
For this reason, there is a problem that it is extremely difficult to efficiently perform the function of preventing the sheet mat from being turned up and the function of preventing sucking out at the same time.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of the conventional sheet mat as described above, so that plants exposed to running water are less likely to be washed away, and at the same time, the sheet mat is connected to the ground by the roots of the plants. In this way, it has a turning-up prevention function to prevent turning up, and at the same time, reduces the flow velocity of the running water on the ground surface, reducing the tractive force, and preventing the movement of sediment in and under the sheet mat. An object of the present invention is to provide a sheet mat having a sweeping force reducing function for preventing earth and sand from being exposed to running water and flowing out by suppressing the earth and sand. Here, the tractive force reduction function will be described.First, the tractive force will be described.This means the force that acts to move the sediment particles on the ground surface when running water flows on the ground. The greater the flow velocity, the greater the tractive force. And when this sweeping force becomes larger than a certain level, earth and sand will move. Therefore, the function of reducing the flow velocity near the ground surface with a sheet mat to reduce the tractive force and prevent earth and sand from moving is called the tractive force reducing function.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a sheet mat for enabling greening of a slope and preventing erosion. It is a porous structure made of a thread-like material, the diameter of the thread-like material is 5 mm or less, the thickness of the porous structure is 5 cm or less, and the void diameter is 0.5 to 2 cm. It is a feature.

According to a second aspect of the present invention, a diameter of 5 mm
It is characterized by laying a greenable erosion-preventing sheet mat made of a porous structure having a thickness of 5 cm or less and a pore size of 0.5 to 2 cm, which is made of a thread-like material having a thickness of 5 mm or less.

According to a third aspect of the present invention, in the second aspect of the invention, plants are vegetated by utilizing the voids of the erosion preventing sheet mat laid.

The invention according to claim 4 is the invention according to claim 2 or 3.
In the invention described in (1), before the plants are vegetated, earth and sand are filled inside the laid erosion-preventing sheet mat that can be laid.

[0010] According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, prior to vegetation of the plant, the thickness of the erosion-preventing sheet mat which is laid can be reduced. Is characterized in that it forms a guest soil layer of approximately 1 to 5 cm.

According to a sixth aspect of the present invention, in the second aspect of the present invention, a plurality of erosion preventing sheet mats are laid adjacent to each other vertically, horizontally and vertically, and the adjacent erosion preventing sheet mats are arranged. Are overlapped with each other, connected by a fixing tool, and fixed to a slope to be laid.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, among the plurality of erosion prevention sheet mats, the erosion prevention sheet mat is laid at the most upstream portion of water flowing on the erosion prevention sheet mat surface. It is characterized in that the upstream end is wound into the soil and fixed to the slope with a fixing tool.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 showing a first embodiment of the present invention, reference numeral 1 denotes a slope, and an erosion-preventing sheet mat for enabling greening of the slope 1 to prevent erosion. The erosion-prevention sheet / mat 2 is a porous structure 4 made of a fibrous material 3, the diameter of the fibrous material 3 is 5 mm or less, and the thickness of the porous structure is 5 cm or less. The gap diameter is 3 cm or less.

Plants 5 are vegetated using the voids of the erosion prevention sheet mat 2 laid. The roots of the plant 5 planted in this way can easily enter the gap, the filamentous material 3 and the root of the plant 5 are easily entangled, and the root of the plant 5 can be easily removed from the lower surface of the porous structure 4. It can penetrate into the ground, prevent the plants 5 from flowing off and prosper, and prevent the erosion prevention sheet / mat 2 from being turned up, thus exhibiting a turning up prevention function.

Further, the flow rate of the flowing water is reduced by the erosion prevention sheet mat 2, and the erosion prevention sheet mat 2 exhibits a sweeping force reducing function, and the earth and sand inside and below the erosion prevention sheet mat 2 flows out and erodes the ground. Can be prevented. In this case, it is preferable that the filament 3 has a diameter of 2 mm or less, a thickness of the porous structure of 3 cm or less, and a void diameter of 0.5 to 2 cm to exert the effect of preventing the turning up.

Prior to vegetation of the plant 5, the inside of the laid greenable erosion prevention sheet mat 2 is filled with earth and sand, and the laid greenable erosion prevention sheet mat 2 is laid. In some cases, the soil layer 6 having a thickness of about 1 to 5 cm is formed. It is desirable to apply fertilizer and water on the slope 1 before laying the erosion prevention sheet / mat 2.

When the erosion prevention sheet mat 2 is laid as described above, instead of laying the erosion prevention sheet mat 2 directly on the site, the erosion prevention sheet mat 2 is placed on another ground other than the slope 1 in the same manner as described above. The erosion prevention sheet / mat 2 may be laid and the plant 5 planted, and then the erosion prevention sheet / mat 2 may be transported to the slope 1 together with the plant 5 and laid.

In this embodiment, the porous structure 4 is made of, for example, a thread-like material formed of a chemical product having resistance to damage, durability, ultraviolet irradiation resistance, weatherability, deterioration resistance, and the like. . For example, a thread material 3 formed by extrusion molding of polyester or polyethylene
And a nonwoven fabric formed by thermoforming.

The above-mentioned specifications of this embodiment are determined based on the data obtained from the results of the experiments actually performed and the values calculated by the following theoretical formulas.
A part of the theoretical formula will be described. There is a tractive force reduction rate R, which represents in percentage how much the tractive force has been reduced by laying the erosion prevention sheet mat 2 on the ground as compared with the case of bare ground, The reduction rate R can be calculated as a function of the porosity resistance coefficient p representing the difficulty of muddy water flow in the erosion prevention sheet mat 2 and the dimensionless thickness a of the sheet. The calculation result with a is as shown in FIG.

A method for determining the thickness of the erosion preventing sheet mat 2 where R = 1% will be described. The diameter d and the void diameter D of the thread material 3 constituting the erosion prevention sheet / mat 2 are determined from the viewpoint of the function of preventing the roll-up. From these, the air gap resistance coefficient p can be calculated by the following equation (1).

(Equation 1) Here, g is a gravitational acceleration of 9.8 (m / s), λ _p is a porosity of the erosion prevention sheet mat 2, and K is a permeability coefficient, which represents the ease of water flow in the erosion prevention sheet mat 2.

The transmission coefficient K can be measured, for example, by the following method. After the erosion prevention sheet / mat 2 is overlapped or the like, the sheet is made as thick as possible, and then placed in a very smooth water channel consisting of a water channel floor and side walls, and water is allowed to flow in a uniform flow state. At this time, the water depth is made smaller than the thickness of the erosion prevention sheet / mat 2. From the measurement results of the thickness of the erosion prevention sheet / mat 2, the average sectional flow velocity V, and the water surface gradient i, the transmission coefficient K can be calculated by the following equation.

(Equation 2) However, in this case, it is desirable to determine K as an average value of several experimental results having different magnitudes of the cross-sectional average flow velocity V and the water surface gradient i from the viewpoint of improving accuracy.

Substituting the values of the porosity λ _p , the diameter d of the thread material 3, the diameter D of the void, and the permeability coefficient K into the above equation (1) to calculate the value of the void resistance coefficient p. Can be. The sheet non-dimensional thickness a is determined from the value of the gap resistance coefficient p, the relationship between the gap resistance coefficient p where R = 1% shown in FIG. 4 and the sheet non-dimensional thickness a. The thickness t of the erosion prevention sheet mat 2 can be calculated by the following equation (3) based on the value of the dimensionless sheet thickness a.

T = a · D (3) Then, the value of the thickness t of the erosion preventing sheet / mat 2 is
From the viewpoint of the function of preventing the roll-up, it may be determined so as to satisfy the relationship between the air gap resistance coefficient p and the dimensionless sheet thickness a, which is 5 cm or less and R = 1% shown in FIG.

FIG. 2 shows a use state of the second and third embodiments of the present invention. These embodiments are examples in which the present invention is applied to the embankment 7, and a plurality of erosion prevention sheet mats 2-1, 1 ′, 2-2 are sequentially arranged from a lower portion of the embankment 7.
2, 2 ', 2-3, 3', 2-4, 4 'are laid and arranged adjacently in the vertical and horizontal directions. In such a case, assuming that water flows in the vertical direction as shown by arrow A on the erosion prevention sheet mat surface as shown in FIG. 3, the upper erosion prevention sheet mat 2 located on the upstream side thereof -2, the back surface of the downstream end 9 is superimposed on the surface of the upstream end of the lower erosion prevention sheet mat 2-1 located on the downstream side, and the erosion prevention sheet The mats 2-1 and 2-2, 2-2 and 2-3, 2-3 and 2-4 are connected, and the fixture 10 is inserted into the ground of the embankment 7 to be fixed and laid.

Referring to FIG. 2 assuming that water flows in the left-right direction as shown by the arrow B in FIG. 3, each erosion prevention sheet mat 2-1 located on the left side and arranged on the upstream side in the drawing. , 2, 3, 4, the downstream end, ie, the right side end, is the upstream side of each of the erosion-preventing sheet mats 2-1 ′, 2 ′, 3 ′, 4 ′ disposed on the downstream side adjacent to the right side The erosion control sheet mats 2-1 and 2-1 ', which are superimposed on the surface of the end, that is, the left end, and are fixed by fasteners 10 such as studs.
2-2 and 2-2 ', 2-3 and 2-3', 2-4 and 2-
4 ′, and the fixture 10 is inserted into the ground of the embankment 7 to be fixed and laid.

The third embodiment of the present invention is shown in FIG. 3 similarly to the second embodiment, and will be described with reference to FIG. It is one of a plurality of erosion prevention sheet mats 2.
The water flowing on the erosion prevention sheet mat surface, the erosion prevention sheet mat laid at the uppermost stream in the vertical and horizontal directions, in this case, the water flows in the left and right direction as shown by arrow B in FIG. Erosion prevention sheet mat 2-1 and 2-
2 (the erosion prevention sheet / mat 2-2 is not shown),
The upstream end portion 8 is bent inward and rolled into the soil of the slope 1, and then enters the ground of the embankment 7 with the fixture 10 and is laid. Note that unlike this embodiment, the water is
Although not shown in FIG. 2, the upstream end of each of the erosion prevention sheet mats 2-4 located on the most upstream side is described with reference to FIG.
It is rolled up on the ground in the same manner as the upstream end 8.

In these second and third embodiments, parts other than the above-mentioned parts may be fixed by the fixture 10, if necessary, and the plant 5 can be vegetated similarly to the first embodiment. Become. And these second and third embodiments are:
Because of the above-described configuration, the seams of the erosion prevention sheet / mat 2 adjacent in the vertical direction and the left / right direction are not firmly joined and turned up. The flowing running water flows between the erosion prevention sheet mat 2 and the ground from the seam that has been turned up,
It will prevent erosion of the ground.

Experimental Example 1 First, as shown in FIG.
Specimens were obtained by the following procedure. A polypropylene resin is heated and melted and extruded from a nozzle with a diameter of 2 mm to process into a thread material, and at the same time, it is folded at random, and the contact points of the thread material are welded and shaped into a porous structure, so that the porosity is 91%, An erosion prevention sheet mat 2 having a thickness of 3 cm, a length of 3 m and a width of 30 cm was obtained. The erosion prevention sheet / mat 2 is laid without gaps on the surface of the sandy soil 11 of 3 m in length, 2 m in width and 60 cm in depth, and the sandy soil 11 is filled in the gaps of the erosion prevention sheet / mat 2. After the soil 12 having a thickness of about 1 cm was put on the erosion-preventing sheet / mat 2, the grass was cured for about 15 months by sticking the wild grass. At this time, the roots of the wild grass extended into the sandy soil filled in the gaps of the erosion prevention sheet mat and reached the soil below the erosion prevention sheet mat (A).

Subsequently, a steel frame 14 having a length of 3 m, a width of 30 cm and a depth of 30 cm is pushed into the ground surface overgrown with wild grass (B), and its surroundings are excavated as shown in (C). As shown in (D), the steel frame 14 is turned sideways, and as shown in FIG.
15 and move it to a predetermined place as shown in (F). Finally, attach the bottom plate to the steel frame 14 as shown in (G).
15 was fixed to obtain a specimen 16 for an erosion experiment.

The test sample 16 was set in a pipe channel experimental device 17 (not shown) in a channel as shown in FIG. Next, the average cross-sectional velocity is 1.0, 2.0, 3.0, 3.5 m / s, and the water depth is about 50c.
Water was passed for 2 to 4 hours under the condition of m, and an erosion experiment was performed to observe the erosion state of the ground surface and the erosion state of wild grass.

[Experimental Example 2] A polypropylene resin is heated and melted and extruded from a nozzle having a diameter of 2 mm to be processed into a thread-like material. At the same time, it is folded at random and the contact points of the thread-like material are welded to form a porous structure. By this, the porosity 96
%, A thickness of 3 cm, a length of 3 m and a width of 30 cm were obtained. An erosion test was performed in exactly the same manner as in Experimental Example 1 except that such an erosion prevention sheet / mat 2 was used.

[Experimental Example 3] A polypropylene resin is heated and melted and extruded from a nozzle having a diameter of 2 mm to be processed into a thread-like material. At the same time, it is folded at random and the contact points of the thread-like material are welded to form a three-dimensional wave. Thus, an erosion preventing sheet mat 2 having a porosity of 96%, a thickness of 3 cm, a length of 3 m and a width of 30 cm was obtained. An erosion test was performed in exactly the same manner as in Experimental Example 1 except that such an erosion prevention sheet / mat 2 was used.

Comparative Example 1 An erosion test was performed in exactly the same manner as in Experimental Example 1, except that no erosion preventing sheet / mat was used.

Comparative Example 2 A polyester fiber having a fineness of 6 denier was subjected to needle punching to a weight of 325 g / m ² and a thickness of 2.7 mm (180 m / cm ³ in terms of fiber density), and was shaped by joining. Experimental Example 1 except that a non-woven fabric sheet having a width of 2 m and a length of 3 m was used, and that the void diameter of the non-woven fabric was smaller than the particle size of the sandy soil, so that no soil was filled in the voids of the non-woven fabric sheet. Erosion experiments were performed in exactly the same way.

[Experimental results] The above experimental examples 1, 2, 3 and
With respect to Comparative Examples 1 and 2, the results of visually evaluating the erosion experiment based on the following criteria A, B, C, and D were as follows. Judgment criteria A: Wild grass is hardly washed away, indicating practicality. B: Erosion partially progressed and the erosion prevention sheet / mat was washed out, but the wild grass was hardly washed away, and it was practical. C: There is a situation where the erosion-prevention sheet / mat is washed out in a certain area where the wild grass is washed away.
Not practical. D: The root layer is turned up over a wide range and is not practical. Evaluation Experimental Example 1 B Experimental Example 2 B Experimental Example 3 A Comparative Example 1 D Comparative Example 2 C

[0035]

The present invention is as described above, and the invention of claim 1 is a sheet mat for enabling greening of a slope and preventing erosion, wherein a porous structure made of a thread-like material is provided. It is a body, the diameter of the thread material is 5 mm or less,
The thickness of the porous structure is 5 cm or less, and the pore diameter is 0.5 to
In the invention according to claim 2, the erosion-preventing sheet mat is laid on the ground, so that the roots of the vegetation planted using the voids of the laid erosion-preventing sheet mat can be used. It is easy to get into the voids, it is easy to get the filamentous material and the plant roots entangled, and the plant roots can invade the ground from the bottom surface of the porous structure, and the plants are not washed away. As it is prevented and prosperous, the erosion prevention sheet / mat is prevented from flipping up, exhibiting the flip-up prevention function, and at the same time, reducing the flow velocity of the flowing water on the ground surface, reducing the tractive force, By suppressing the movement of earth and sand in and under the erosion prevention sheet / mat, there is an effect of exerting a sweeping force reducing function that can prevent the seedlings and earth and sand from being exposed to running water and flowing out. .

According to a third aspect of the present invention, in the second aspect of the present invention, plants are vegetated by utilizing the voids of the erosion preventing sheet mat laid.
Prior to vegetation of the plant, the inside of the laid greenable erosion-preventing sheet mat is filled with earth and sand, and the invention according to claim 5 lays down the vegetable green laid before planting the plant. Because the soil layer of about 1-5cm thickness is formed on the erosion prevention sheet mat, the roots of the vegetated plants can easily enter the voids, and the filamentous material and the roots of the plants It is easy to entangle, and the roots of the plant can penetrate into the ground from the bottom of the porous structure, preventing the plant from flowing out and growing, and preventing the sheet mat from turning up. In addition, there is an effect that a function of preventing a turning up can be exhibited.

According to a sixth aspect of the present invention, in the second aspect of the present invention, a plurality of erosion prevention sheet mats are laid adjacent to each other vertically and horizontally, and the adjacent erosion prevention sheet mats are provided. The ends of are polymerized and fixed by a fixing tool and fixed to the slope, and the invention of claim 7 is the invention of claim 6, wherein The erosion prevention sheet is laid at the most upstream portion of the water flowing on the mat surface, but the upstream end is wound into the soil and fixed to the slope by the fixing tool, so that the erosion prevention sheet adjacent in the vertical and horizontal directions.
The seams of the mats are firmly joined, and the upstream end of the most upstream part is firmly held on the ground, and the flowing water from these parts on the erosion prevention sheet mat Thus, there is an effect that it can be prevented from flowing into the ground and eroding the ground.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a use state of a first embodiment of the present invention.

FIG. 2 is a perspective view showing a use state of the second and third embodiments of the present invention.

FIG. 3 is a perspective view showing a use state of the second and third embodiments of the present invention surrounded by a line 3 of the same.

FIG. 4 is a correlation diagram between the dimensionless thickness of the erosion prevention sheet mat and the air gap resistance coefficient.

FIG. 5 is an explanatory view showing a procedure for obtaining a specimen for obtaining an experimental example of the erosion prevention sheet / mat in the same order as (A) to (G).

FIG. 6 is an explanatory diagram showing an experimental state in the experimental example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slope 2 Erosion prevention sheet / mat 3 Thread material 4 Porous structure 5 Plant 6 Guest soil layer 7 Embankment 8 Upstream end 9 Downstream end 10 Fixture

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kengo Hori 1 Asahi, Tsukuba, Ibaraki Pref. Public Works Research Institute, Ministry of Construction (56) References JP-A-6-10324 (JP, A) (58) Fields investigated ( Int.Cl. ⁶ , DB name) E02B 3/12 E02D 17/20 102

Claims (7)

(57) [Claims] 1. A sheet mat for enabling greening of a slope and preventing erosion, wherein the sheet mat has a porous structure made of a thread-like material, and the diameter of the thread-like material is 5 mm or less, The thickness of the porous structure is 5 cm or less, and the pore diameter is 0.1 cm.
An erosion-preventing sheet mat capable of being greened, which is 5 to 2 cm. 2. A greenable erosion preventive sheet mat comprising a porous structure having a diameter of 5 mm or less, a thickness of 5 cm or less, and a void diameter of 0.5 to 2 cm on a slope. Ground protection method characterized by laying. 3. The ground protection method according to claim 2, wherein the vegetation is vegetated by utilizing the voids of the erosion prevention sheet mat laid. 4. The ground protection method according to claim 2, wherein earth and sand are filled inside the laid erosion-preventing sheet mat which is laid before planting the plant. 5. The method according to claim 5, wherein the step of laying the vegetation on the vegetable erosion control sheet mat has a thickness of approximately 1%.
3. The structure according to claim 2, wherein a soil layer of about 5 cm is formed.
5. The ground protection method according to any one of items 1 to 4. 6. A plurality of erosion prevention sheet mats are laid adjacently vertically and horizontally, and ends of adjacent erosion prevention sheet mats are overlapped and connected by a fixing tool,
The ground protection method according to any one of claims 2 to 5, wherein the ground protection method is fixed to a slope. 7. The invention according to claim 6, wherein an upper end portion of a plurality of erosion prevention sheet mats laid at the most upstream portion of water flowing on the erosion prevention sheet mat surface is rolled into the soil. A ground protection method characterized by being fixed to a slope by a fixing tool.