JP2001254330A - Erosion prevention mat and its laying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an erosion prevention mat and its laying method which is a netting body capable of preventing the erosion of the face of slope of a levee due to running water while greening the face of slope, of avoiding the runoff of vegetation, of reducing the cost of work execution and also providing good appearance. SOLUTION: For the first invention, a thermoplastic resin tape with a thickness of 30 to 500 μm and a width of 0.2 to 3.0 mm is made to a gap (knot) of 1 to 5 mm and the percentage of perforation of 10 to 80%; and to one surface of a ground fabric net woven to a grid shape, a thermoplastic resin tape having the thickness of 20 to 500 μm, the width of 0.2 to 3.0 mm is formed to a level tape with the height of 5 to 40 mm and attached; the restoration percentage in the elongation recovery test is less than 110%, elongation percentage is less than 10%, and loop test strength is more than 10 kgf are provided as a mat for the erosion prevention; and the second invention describes a laying method for this erosion prevention mat, thereby solving the problem stated above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mat for preventing erosion and a method of laying the same. More specifically, the present invention relates to an erosion prevention mat which is used in a ground protection method for preventing erosion due to flowing water on a river dike slope or a river bank, is easy to construct, and can be greened, and a method of laying the mat.

[0002]

2. Description of the Related Art Embankments such as rivers, high water beds, river banks, etc.
Generally, it has a sectional structure shown in FIG. That is,
Crest a2, which is the flat top surface of the embankment a1, a slope a3, a3 'consisting of a surface gently inclined downward from this crest a2,
Small steps a4, a4 'consisting of relatively narrow flat surfaces provided in the middle of the slopes a3, a3', high water beds a5 consisting of relatively wide flat parts provided at the foot of the front surface a3, and further high water beds It consists of a river bank a6 that slopes down from the end of a5. The height of the riverbank a6 is designed so that the flowing water a7 does not exceed the edge of the riverbank a6 when the river flows at a normal flow rate. Front side
It is required that a3 and table a4 have a function to protect the levee from erosion due to flowing water and prevent flood damage due to levee breach during emergency flooding when the amount of flowing water temporarily increases. It is very important to protect the table and a4.

Conventionally, a method of laying vegetation such as concrete, concrete blocks, stones, and upholstery on the surface has been adopted for protection of slopes and small steps. However, when using concrete, concrete blocks, stones, and the like, there is a drawback that the construction work becomes large, the construction cost increases, and the appearance after the completion of the construction work is poor.
On the other hand, the method of spreading vegetation such as turf is easy to construct, the construction cost is not high, and it is preferable from the viewpoint of aesthetics.
There was a risk that the vegetation would be washed away by the flooding during the flooding, and the embankment could not be protected from erosion by the flowing water. For this reason, the embankment can be protected from erosion due to flowing water, the construction work cost is not increased, and a ground protection method such as an embankment, which is also preferable from an aesthetic standpoint, has been awaited.

[0004] On the other hand, various methods have been proposed for greening, protecting and strengthening the slope. For example,
-5, JP-B-54-4167, JP-A-2-
No. 47428, JP-A-6-10324, JP-A-10-317352 and the like. Japanese Patent Publication No. 45-5 discloses that a mat filled with seeds and earth and sand is laid in the space of a fibrous plate-like material having coarse gaps and bonded by bitumen or the like, thereby preventing the collapse of the earth and sand by growing the grass. The technology to do this is described. However, the voids in the fibrous plate-like material of this mat are so coarse that they can be seen through, and in the case of flooding, etc., the soil filled in the voids of the fibrous plate-like material by running water and the fibrous material There was a risk that the plate-like material was peeled off along with the root and was washed away.

[0005] Japanese Patent Publication No. 54-4167 discloses a method in which a mat having many gaps is stretched on a slope, and concrete or the like is sprayed in a grid, and then the seed or fertilizer is sprayed to green the slope. Has been described. This method also has a large mat gap (mesh size) of 2 to 5 cm.
If this is used for the protection of embankments, there is a risk of running away seeds and fertilizers sprayed on the slopes and running off soil from between the mat grids due to running water in the event of floods.

Japanese Patent Application Laid-Open No. 2-47428 discloses 5-2
Fill a fibrous body and soil inside a box with a through hole of about 0 mm, fix this box on a slope, grow plants in this soil, and protect the slope with greening. A method is described. However, the method proposed here is intended to generally protect the slope by greening and protection, and to prevent landslides and spills due to rainwater. When diversion is used for the protection of the embankment, the through hole of the box is large and the distance between the walls of the box is large.
In the case of flooding, there was a risk that the soil packed in the voids inside the box would be washed away by running water, and that the box would be peeled off with its roots.

[0007] Japanese Patent Application Laid-Open No. 6-10324 discloses that roots of plants vegetated on a nonwoven layer having a fiber density of 10 to 2000 m / cm3 laid on the surface of a dike are stretched on the dike soil via the nonwoven layer. A method is described. However, in this method, the roots of the plants vegetated on the nonwoven layer are difficult to reach the embankment soil due to the high fiber density of the nonwoven fabric, and in the case of flooding, the vegetation of the plants vegetated on the nonwoven layer by running water, In addition, the nonwoven fabric laid on the surface of the embankment could be peeled off and run off.

Japanese Patent Laid-Open No. Hei 10-317352 proposes an erosion-preventing sheet mat which can be greened. The erosion protection sheet mat described in this publication is
It is a porous structure made of filamentous material, which can prevent erosion of embankment slopes and river banks by running water, and the loss of plants. In addition, when laying the erosion prevention sheet / mat described in this publication on a slope, the ends of the erosion prevention sheet / mat are overlapped with each other, and the ends are wound into the soil and fixed. There is also described a ground protection method for fixing a slope to a slope or the like, filling the voids of an erosion prevention sheet / mat with earth and sand, forming a soil layer, and vegetating plants.

However, as a result of actually performing a laying test using the erosion preventing sheet / mat, it was found that there were the following two drawbacks. That is, for example, when the erosion prevention sheet mat is laid, if human or mechanical force acts on the erosion prevention sheet mat, the erosion prevention sheet mat may be damaged. For example, the function of preventing erosion of a riverbank or a slope by running water may be significantly impaired. Two,
It is sometimes difficult to efficiently and satisfactorily fill the voids of the erosion prevention sheet mat with the earth and sand. In order to lay this erosion prevention sheet mat practically and efficiently,
It was found that the structure of the erosion prevention sheet / mat, such as the diameter, gap (mesh size), and perforation rate, of the thread-like material constituting the erosion prevention sheet / mat had to be adjusted, and the strength had to be adjusted similarly.

[0010]

DISCLOSURE OF THE INVENTION The present inventors have found that there is no danger of vegetation runoff, the cost of laying is not high, and the aesthetically pleasing embankment slope can be greened to prevent erosion while greening. As a result of intensive studies to provide an erosion prevention mat and a method of laying the same, the present invention has been achieved. That is, the objects of the present invention are as follows. 1. To provide an erosion control mat without risk of vegetation runoff. 2. To provide an erosion prevention mat that does not increase construction costs. 3. To provide an erosion prevention mat that is also aesthetically pleasing. 4. To provide a method for laying the erosion prevention mat.

[0011]

In order to achieve the above object, according to a first aspect of the present invention, a thickness of 30 to 500 μm is provided.
A stretched tape made of a thermoplastic resin having a width of 0.2 to 3.0 mm and a gap (mesh size) of 1 to 5 mm and a hole opening rate of 10 to 80
% On one side of the base cloth net woven in a grid
A stretched tape made of a thermoplastic resin having a width of 0 to 500 μm and a width of 0.2 to 3.0 mm is attached to form a level loop at a height of 5 to 40 mm, and the recovery rate in an elongation recovery test is 110. %, An elongation percentage of 10% or less, and a hook test strength of 10 kgf or more.

In the present invention, when the erosion prevention mat is laid on a dike slope or the like, the erosion prevention mat has a thickness of 30 to 500 μm and a width of 0.2 to 3.0.
mm stretched thermoplastic resin tape with a gap of 1
Stretched tape made of a thermoplastic resin having a thickness of 20 to 500 μm and a width of 0.2 to 3.0 mm on one surface of a base fabric net woven in a lattice with a hole opening ratio of 10 to 80 mm and a hole opening ratio of 10 to 80%. Is 5
A level loop was formed at a height of 40 mm and attached. The restoration rate in the elongation recovery test was 110% or less, the elongation rate was 10% or less, and the hooking test strength was 10 kgf or more. Fill the level loop formed on one side of the erosion prevention mat with earth and sand, and insert the roots of the plants vegetated on the loop of the erosion prevention mat through the holes in the base cloth net of the erosion prevention mat. Provided is a method for laying an erosion prevention mat, which is characterized in that the erosion prevention mat is laid on a slope.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The erosion prevention mat according to the first invention of the present invention is manufactured using a stretched tape made of a thermoplastic resin as a raw material. Specific examples of the thermoplastic resin used for producing the base cloth net of the erosion prevention mat and the stretched tape for the level loop include polyethylene, ethylene-vinyl acetate copolymer, olefin-based resins such as polypropylene, polyvinyl chloride. , Vinyl chloride resins such as copolymers containing vinyl chloride as a main component, polyvinylidene chloride, polyvinylidene chloride resins such as a copolymer containing vinylidene chloride as a main component, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. , Polyamide-based resins such as polyamide 6, polyamide 6.6, polyamide MXD, polycarbonate,
An acrylic resin such as polymethyl methacrylate, polyvinylidene chloride, and the like can be given. The thermoplastic resin is not limited to those exemplified above. The type of the thermoplastic resin can be selected or mixed according to the strength given to the stretched tape, and can be used by mixing.

The thermoplastic resin may be blended with various types and amounts of resin additives which do not adversely affect the strength and the like of the stretched tape. Examples of the resin additives include colorants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, fillers, rust inhibitors, foaming agents, and the like.

[0015] The stretched tape made of a thermoplastic resin is a tape whose width is adjusted by extruding it into a band or a film by an extrusion molding method and stretching it uniaxially. Both the base fabric net and the level loop may be formed of flat yarn, split yarn, or the like. In addition, both the base cloth net and the level loop may be formed of tape, flat yarn, split yarn, or the like, alone, without being twisted, by simply overlapping or converging, or by twisting a plurality of yarns. The stretch ratio of the stretched tape is preferably selected in the range of 4 to 20 times.

An example of the erosion prevention mat according to the first invention of the present invention, FIG. 2 is a partial plan view of an example of a base cloth net constituting the erosion prevention mat, and FIG. FIG. 4 is a side view showing an example of a state where a loop is attached, and FIG. 4 is a back view showing an example of a state where a yarn is attached to a base cloth net. The base cloth net is made of a thermoplastic resin stretched tape having a thickness of 30 to 500 μm and a width of 0.2 to 3.0 mm woven in a lattice shape, or a woven lattice tape woven at a crossing point. It may be welded.

The grid-like base cloth net has a gap (mesh) of one.
５5 mm, and the perforation rate is 10-80%. Gap
Is less than 1 mm and the perforation rate is less than 10%, it is difficult for plant roots to reach the embankment soil when laid on the embankment soil, and the erosion prevention mat is firmly fixed to the embankment soil. This is not preferable because it takes too long. If the gap (mesh) exceeds 5 mm and the hole opening rate exceeds 80%, the mesh of the base fabric net becomes too coarse, it becomes difficult to attach the level loop, and the density of the level loop to be attached is undesirably reduced. The number of yarns attached per unit area of the base fabric net is preferably 15 to 1000 pieces / m 2, and more preferably 50 to 700 pieces / m 2.

The mat for preventing erosion according to the present invention has a thickness of 20 to 500 μm on one surface of the grid-like base cloth net.
A stretched tape made of a thermoplastic resin having a width of 0.2 to 3.0 mm and a level loop is attached. The level loop may be formed by laminating three to ten stretched tapes, not twisting or twisting at a rate of one to several times per inch, and bonding them with an adhesive, or may be attached by a weaving method. The height of the level loop from the base fabric net is in the range of 5 to 40 mm. The height of the level loop from the base cloth net is 5mm
If it is less than the amount of sediment retained by the level loop when laying on the embankment soil is small, it will be difficult to plant vegetation on it, and if the height exceeds 40 mm, it will be retained by the level loop Since the amount of sediment is too large, it takes too much time for the roots of the plants to reach the embankment soil when plants are vegetated thereon, so neither is preferable.

The erosion preventing mat according to the present invention preferably has a restoration rate of 110% or less and an elongation rate of 10% or less in an extension recovery test. In the present invention, the "stretch recovery test" refers to a method in which one end in the length direction of the erosion prevention mat having a width of 60 cm and a length of 1 m is fixed, and the other end is pulled at a force of 30 kgf / 60 cm for 10 seconds to release the pulling force. One minute after the test, the length of the original erosion prevention mat is measured, and the ratio to the length after the stretch recovery test is calculated and evaluated. When the length after the stretch recovery test is 110% or less of the original length, it is preferable because the length is not excessively stretched when actually laid.

In the present invention, the “elongation” refers to a width 60 c
This is a test method in which the length of one end of the erosion prevention mat having a length of 2 m in the length direction is measured by hand while being lifted by hand, and compared with the length before lifting. The elongation percentage by this test is 1
When it is 0% or less, it is preferable because it does not extend too much when actually laid.

The erosion preventing mat according to the present invention has a hook test strength of 10 kgf or more. In the present invention, the "hook test strength" refers to a 275 mm long, 200 mm wide erosion prevention mat at a position 5 cm each along the longitudinal direction from the center point of the mat.
Holes are drilled (the distance between the two holes is 10 cm), a fixed hook is hooked into this hole and extended in the vertical direction, one of the hook shafts is fixed to the fixture, and the other of the hook shafts is spring-loaded. However, if the tensile load is slowly increased until the tensile load reaches 10 kgf, and it does not break even if the tensile load exceeds 10 kgf, it is regarded as “pass”. If it breaks at less than 10 kgf, the strength is insufficient when actually used, which is not preferable.

Hereinafter, a procedure for laying the erosion preventing mat on the embankment soil will be described. As a method of laying, (1)
An erosion prevention mat is laid on the embankment soil at the laying site, and the voids formed between the level loops are filled with earth and sand. (2) After laying the plant on the other ground in the same way as (1), in a different place from the embankment to be laid, on the mat layer for preventing erosion and the embankment soil under it And a method of laying the roots of the vegetated plants on the mat layer for preventing erosion and the embankment soil thereunder, by laying the roots of the vegetated plants together with the vegetated plants.

When the erosion prevention mat is laid on the front slope a3 or the front small step a4 of the embankment by the laying method according to the present invention, when the embankment is flooded, erosion of the embankment soil by running water is prevented. The loss of plants can also be prevented. On the other hand, also in the case of laying on the back slope a3 ', the back small step a4', or the top end a2, even if the river water overflows the embankment, it can be prevented that the embankment is eroded and collapsed. In other words, if the erosion prevention mat according to the present invention is laid and vegetated on the entire surface of the embankment, the embankment can be prevented from being eroded by running water.
The laying method according to the present invention can also be applied to riverside slopes and small steps such as rivers, artificial waterways, canals, lakes and marshes in the same situation as the front slope a3 and the front small steps a4 in the embankment.

Hereinafter, the present invention will be described in detail with reference to the drawings and embodiments, but the present invention is not limited to the following description unless it exceeds the gist.

FIG. 5 shows that the erosion prevention mat b1 is connected to the embankment soil a11.
A partially enlarged longitudinal view schematically showing a state in which the soil b6 is placed on the erosion prevention mat b1, the plant b7 is grown, and the root b7 is stretched in the embankment soil a11. FIG. Figure 6 shows the top a2, the slope a3, and the small steps of the river embankment
FIG. 4 is a longitudinal sectional view schematically showing a state in which a4 is protected by an erosion prevention mat b1. That is, erosion prevention mats b11, b12, b13 and b14 are laid in order from the lower part of the embankment a1, but before placing each erosion prevention mat on the embankment soil a11, fertilizer is sprayed on the surface of the embankment soil. It is preferable to spray water.

After laying the erosion prevention mat b11, the lower end of the erosion prevention mat b12 is superimposed on the upper end of the erosion prevention mat b11. Both are fixed with a suitable fixing tool b15 such as a tack, and then an erosion prevention mat b13 is similarly laid thereon. In addition, if necessary, the soil (not shown) is placed on the erosion prevention mat, sowing or pasting is performed, the plants are grown, and the roots are stretched in the embankment soil a11.
The embankment is greened and protected.

Example <Erosion Prevention Mat> A 35 μm thick and 2 mm wide polyethylene tape stretched 15 times in one axial direction was subjected to a gap (mesh) as shown in a plan view in FIG. Five pieces of 20 μm thick, 2 mm wide polypropylene uniaxially stretched 15-fold tape were woven into a grid net with 3 mm, 30% hole opening rate and woven in a grid and joined at the intersections by heat welding. As shown in the back view of FIG. 4, the tape laid once and twisted once per inch is woven into the base cloth net, and a loop having a height of 15 mm is formed on the front side of the base cloth net to prevent erosion. And The erosion prevention mat has a recovery rate of 101% in an elongation recovery test, an elongation rate of 3%, and a hook test strength of 17%.
kgf.

<Erosion test of vegetation> Length 3 m, width 2
The erosion prevention mat b1 is laid without gaps on the surface of sandy soil d1 having a depth of 60 cm and a depth of 60 cm.
Fill the void formed between the level loops of b1 with sandy soil, and further load the soil d2 at a height of about 1 cm.
And cured for about 15 months. Noshiba d4 after curing
The roots of the root extended to the sandy soil d1 filled in the voids of the erosion prevention mat b1 and reached the soil under the erosion prevention mat b1 (see FIG. 7A).

Subsequently, as shown in FIG. 7B, a rope frame d4 having a length of 3 m, a width of 30 cm, and a depth of 30 cm is placed on a wild grass d3.
Was pushed into the overgrown ground surface, the surrounding area was excavated, the rope frame d4 was turned down, and a bottom plate d5 was attached and fixed to the rope frame d4 to obtain a test block d6 for an erosion test. This test block
d6 is replaced with a channel d7 (width 3) in a pipe channel test device (not shown).
0 cm, height 50 cm, length 5 m, see FIG. 8).
Then, the cross-sectional average flow rates 1.0, 2.0, 3.0, 3.5
An erosion experiment was performed in which water was passed from the direction of the arrow for 2 to 4 hours under the conditions of m / sec and a water depth of about 50 cm, and the erosion state of the ground surface and the erosion state of Noshiba d3 were observed. According to the experimental results, under the test conditions where the cross-sectional average flow velocity is high and the water passage time is long, the erosion prevention mat b1 is partially washed out and the erosion prevention mat b1 is washed out, but there is almost no loss of the wild grass d5, There was no problem in practical use.

Comparative Example <Vegetation Erosion Test> In the erosion test described in the Examples,
An erosion experiment was performed in the same procedure as described in the same example except that the erosion prevention mat b1 was not used. According to the experimental results, the turn-up of the root layer of wild turf was observed over a wide range, indicating that it was not practical.

[0031]

The present invention has been described in detail above, and has the following particularly advantageous effects, and its industrial utility value is extremely large. 1. The erosion prevention mat according to the present invention is lightweight, easily filled with earth and sand between the level loops, and the roots of the vegetation can easily reach the embankment soil through the holes provided in the base fabric net. It can be suitably used for greening a slope or the like. 2. Since the erosion prevention mat according to the present invention is filled with earth and sand between the level loops, it is difficult for rainwater to enter the embankment soil during rainfall, and when draining after flooding, the embankment soil is not washed away. , Softening of the embankment can be prevented. 3. In the erosion prevention mat according to the present invention, the earth and sand filled between the level loops is held by the roots of the vegetated plants, reaches the embankment soil, and is stretched around the embankment, so that it is easily exposed to running water. There is no peeling and no risk of spills.

4. The erosion prevention mat according to the present invention has a restoration rate of 110% or less and an elongation rate of 10% in an extension recovery test.
Hereinafter, when the hook test strength is 10 kgf or more, excellent strength and excellent durability are exhibited when actually applied. 5. When the erosion prevention mat according to the present invention protects a dike slope or a small step, a conventional concrete,
Compared to the method of protecting embankment slopes and small steps with concrete blocks, stones, etc., the construction work is not large and the construction cost is not increased. 6. In the case where the erosion prevention mat according to the present invention is laid on a dike slope or a small step to protect the erosion prevention mat, conventional aesthetics are preferable as compared with the case where conventional concrete, concrete blocks, stones, and the like are used. It can be a protective surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a typical structure of an embankment.

FIG. 2 is a partial plan view of an example of a base fabric net constituting the erosion prevention mat according to the present invention.

FIG. 3 is a side view of an example of a state in which a level loop is attached to a base cloth net.

FIG. 4 is a back view of an example of a state in which a loop is attached to a base cloth net.

FIG. 5 is a partially enlarged longitudinal sectional view schematically showing a state in which the erosion prevention mat according to the present invention is constructed.

FIG. 6 is a longitudinal sectional view schematically showing a state in which the top end, a slope, and a small step of a river embankment are protected by an erosion prevention mat.

FIG. 7 is an explanatory view showing a procedure for obtaining a test block for an erosion test in the embodiment.

FIG. 8 is a perspective view showing an implementation state of an erosion test in the example.

[Explanation of symbols]

a1: Embankment a2: Top end a1, a4 ': Small step a5: High water floor a6: River bank a11: Embankment soil b1, b11, b12, b13, b14: Erosion prevention mat b2: Base cloth net b3: Intersection b4 : Level loop b5: Loop intersection b6: Guest soil b7: Plant b8: Root b15: Fixture d1: Sandy soil d2: Guest soil d3: Noshiba d4: Steel frame d5: Bottom plate d6: Test block d7: Waterway

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Hattori, 1st Asahi, Asahi, Tsukuba, Ibaraki Prefecture Within the Public Works Research Institute, Ministry of Construction (72) Inventor Susumu Yoshikawa 4-4-2 Nihonbashi Honcho, Chuo-ku, Tokyo Mitsubishi Chemical Inside (72) Inventor Hideto Shintani 4-4-2 Nihonbashi Honcho, Chuo-ku, Tokyo Mitsubishi Chemical Industrial Co., Ltd. F-term (reference) 2D018 DA02 2D044 DA12 DB04

Claims (2)

[Claims] 1. A thickness of 30 to 500 μm and a width of 0.2
A stretched tape made of a thermoplastic resin having a thickness of 20 to 3.0 mm is formed on one side of a base cloth net woven in a lattice with a gap (mesh size) of 1 to 5 mm and a hole opening rate of 10 to 80%. ~ 500 μm
A stretched tape made of a thermoplastic resin having a width of 0.2 to 3.0 mm is attached by forming a level loop at a height of 5 to 40 mm, and a recovery rate in an elongation recovery test is 110% or less. An erosion prevention mat characterized by having an elongation of 10% or less and a hook test strength of 10 kgf or more. 2. When laying an erosion prevention mat on a levee slope or the like, the erosion prevention mat has a thickness of 30%.
Base cloth woven in a lattice shape with a stretched tape made of thermoplastic resin having a width of 0.2 to 3.0 mm and a gap (mesh size) of 1 to 5 mm and a piercing rate of 10 to 80%. On one side of the net, the thickness is 20-500 μm and the width is 0.2-3.0 mm
Stretched tape made of a thermoplastic resin and having a level loop formed at a height of 5 to 40 mm, with a recovery rate of 110% or less in an elongation recovery test, an elongation rate of 10% or less, and a hook test strength. Is set to 10 kgf or more. The level loop formed on one side of the erosion prevention mat is filled with earth and sand, and the roots of the plants vegetated on the loop of the erosion prevention mat are removed from the erosion prevention mat. A method for laying erosion prevention mats, characterized in that earth and sand is stretched on embankment slopes through holes in the base cloth net of the mat.