JP2587741B2 - Embankment protection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an embankment protection method. In particular, the present invention relates to a method for protecting a slope of a dike, a small step, and a riverbank which may be flooded when a river or the like temporarily increases in water level.

[0002]

2. Description of the Related Art Embankments such as rivers generally have a sectional structure shown in FIG. That is, the top 2 which is the flat top surface of the embankment 1, the slopes 3 and 3 ′ which are surfaces gently inclined downward from the top 2, and the comparison provided in the middle of the slopes 3 and 3 ′. Small steps 4 and 4 'consisting of a relatively narrow flat surface, a high water bed 5 consisting of a relatively wide flat part provided at the foot of the front slope 3, and
It is composed of a low-water riverbank 6 that slopes downward from the end of the high-water bed 5. The height of the low-water shore 6 is designed so that the flowing water 7 does not exceed the upper end of the low-water shore 6 when the river is flowing at a normal flow rate. On the other hand, the height of the front slope 3 is designed so that the flowing water 7 does not exceed the top 2 even when the amount of flowing water in the river temporarily increases significantly due to a typhoon or heavy rain. That is,
The front slope 3 and the front small step 4 serve to protect the surface of the dike from running water and prevent flood damage due to the break of the dike in an emergency when the amount of flowing water temporarily increases. Therefore, it is very important to protect the front slope 3 and the front small steps 4 in order to prevent flood damage due to the levee collapse.

Heretofore, for the protection of slopes and small steps, there has been adopted a method in which vegetation such as concrete, concrete blocks, stones, and upholstery is spread over the surface to prepare for an emergency. But concrete, concrete blocks,
In the case of using a stone material, there are disadvantages in that the construction is large, the construction cost is high, and the appearance is impaired. On the other hand, the method using vegetation such as turf is easy and the construction cost is low, and it is also aesthetically pleasing.However, there is a risk that the vegetation will flow out and the embankment will be softened by the flooding during the flooding. there were. For this reason, there is no danger of vegetation flowing out, construction is easy, the construction cost is low, and an aesthetically favorable embankment protection method has been long-awaited.

[0004] On the other hand, various methods have been proposed for greening the slopes to protect and strengthen them. For example, Japanese Patent Application Laid-Open
Japanese Patent No. 220613 discloses that a fibrous body and soil are packed in a box having a through hole of about 5 to 20 mm, the box is fixed to a slope, and then a plant is grown in the soil. And a method for protecting a slope from greening. However, this method is aimed at greening and protecting slopes in general and preventing landslides and runoff due to rainwater, and is not intended to protect embankments.
Therefore, even if the surface of the embankment is treated in this way, the pores of the box are large and the spacing between the boxes is large, so that in case of flooding, etc. There was a risk that the whole was peeled off and leaked.

Japanese Patent Application Laid-Open No. 2-47428 discloses that a thick mat having a large porosity is laid on a slope with a net body, and a concrete block is placed and fixed on a mortar laid in a spot shape on the net body. A method of protecting slopes by vegetation on the soil between blocks is described. This method is not intended to protect the embankment in particular, but uses mats and nets with a large porosity, so even if the surface of the embankment is treated in this way, in the case of floods, etc. There is a risk that soil and plants and the roots of the embankment will flow out. Further, Japanese Patent Publication No. 54-4167 describes a method in which a mat with a lot of clearance is stretched on a slope, and after spraying concrete or the like, seeds or fertilizer are sprayed to green the slope. However, this method is also not intended to protect and strengthen the embankment, and the gap of the mat is large (approximately 2 to 5 cm).
As in the method described in JP-A-47428, it does not sufficiently fulfill the purpose of protecting the surface of the embankment.

Furthermore, Japanese Patent Publication No. 45-5 discloses that a mat filled with seeds and earth and sand is laid in the voids of a fibrous plate-like material having coarse voids and joined by bitumen or the like. A technique for preventing the collapse of earth and sand is described. However, the voids in the fibrous plate-like material of this mat are so coarse that they can be seen through.
Similar to the methods described in Japanese Patent Publication No. 7428 and Japanese Patent Publication No. 54-4167, they do not sufficiently fulfill the purpose of revetment.

[0007]

SUMMARY OF THE INVENTION The present inventor has solved the drawbacks of the prior art, that is, the construction is easy, the economy is excellent, the appearance is excellent, and the vegetation is exposed not only during rainfall but also when exposed to running water during flooding. And the embankment sediment is not discharged,
In addition, after the flooding was completed, the search for a so-called embankment protection method that does not require or can be easily repaired, and surprisingly, when combining a nonwoven fabric with a high fiber density and a plant, It has been found that the above object can be achieved. The present invention is based on such findings.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method of embankment embankment embankment through a non-woven fabric layer, wherein the roots of plants vegetated on a non-woven fabric layer having a fiber density of 10 to 2000 m / cm ³ laid on the surface of the embankment. The present invention relates to a method for protecting a dike, which is characterized in that the dike is stretched on body soil.

In the present invention, the fiber density D is 10 to 2000 m /
A high density nonwoven sheet of cm ³ , preferably 20 to 200 m / cm ³ is used. In this specification, the fiber density D (m /
cm ³ ) is defined by the following formula (1) D = [(weight per unit area (g / cm ² ) / fineness (d) × thickness (cm)] × 9000 (1) where the fineness (d ) Is the weight (g) per 9000 m of the fibers constituting the non-woven fabric.If the fiber density exceeds 2000 m / cm ³ , the roots of the plant will not pass, which is not preferable, and if the fiber density is lower than 10 m / cm ^3, Also, the water permeability is too high in the thickness direction of the nonwoven fabric sheet, so that rainwater enters into the embankment and the sediment of the embankment body flows out by running water, which is not preferable.

The method for producing the nonwoven fabric sheet used in the present invention is not particularly limited, and for example, a nonwoven fabric sheet obtained by a card method, an air lay method, a spun bond method, or the like may be used. When such a nonwoven fabric sheet is laid on the surface of the embankment, the water permeability in the horizontal direction (substantially parallel to the embankment soil surface) is greater than that in the thickness direction (direction substantially perpendicular to the embankment soil surface) during precipitation. The coefficient is higher and the slope of the embankment slope makes it more difficult for rainwater to enter the embankment and the embankment is less likely to soften. In addition, when the water that has entered the embankment during the flooding is drained, the gap in the nonwoven fabric sheet is small and the embankment soil does not flow out, so that the embankment is not softened and the embankment can be protected. In addition, the nonwoven fabric sheet is finished with at least one side fluffed to some extent,
It is preferable to increase the coefficient of friction with the embankment soil to improve workability.

The fibers of the nonwoven fabric used in the present invention are not particularly limited, but nonwoven fabrics produced by heat-sealing olefin fibers are preferred from the viewpoints of weather resistance, chemical resistance and corrosion resistance. . Although the thickness of the nonwoven fabric sheet is not particularly limited, it is preferably 1 to 30 m.
m, more preferably 1 to 15 mm. When the thickness is less than 1 mm, the tensile strength and the like become insufficient, and when the thickness exceeds 30 mm, the root permeability of the plant decreases, which is not preferable. The length and width of the nonwoven fabric sheet can be appropriately adjusted according to the place where the sheet is laid.

In the method of the present invention, plants are vegetated on the nonwoven fabric sheet. This plant penetrates the nonwoven sheet,
Since it is integrated with the embankment earth and sand via the nonwoven fabric sheet, it is preferably about 5 cm or more, although it depends on the thickness of the nonwoven fabric sheet. When plants having a plant height of about 5 to 50 cm (more preferably, 8 to 40 cm) are vegetated or the plant height of the vegetated plants is maintained in this range, the plant height is increased by flowing water during flooding, and the surface of the nonwoven fabric sheet is completely covered. Water is less likely to penetrate into the embankment, and the plant height acts as resistance against running water, and the flow velocity near the surface of the nonwoven fabric sheet is reduced, so that scouring is difficult. Since the plant height cannot be shorter than about 5 cm, the effect of preventing water intrusion and scouring cannot be sufficiently obtained. When the plant height exceeds about 50 cm, the force acting on the plant height increases, and the plant height is torn. May leak out. Examples of such plants include, but are not limited to, Japanese turf, such as Noshiba, Wrangler species, and Western turf, such as Kentucky 31. In addition, these plants need not be of one kind, and may be vegetated in combination of two or more kinds.

[0013] If necessary, a soil of about 1 to 7 cm is provided on the nonwoven fabric sheet to promote plant growth,
Further, the light resistance and weather resistance of the nonwoven fabric layer are also improved, which is preferable. The vegetation method of the plant is not particularly limited,
For example, a well-known solid, jointed, tiled, checkered, or streaked turf can be used for turf vegetation, and the curing is no different from normal turf curing. Nonwoven fabrics are also excellent in water retention and are suitable for growing plants.

Laying a non-woven fabric sheet on the embankment soil and, if necessary, laying the soil on the embankment and then sticking or sowing the plant to grow the plant, and stretching the roots of the plant on the non-woven fabric layer and the embankment under the embankment Thus, the method of the present invention can be carried out. Alternatively, before laying on the embankment surface, place the soil on a nonwoven sheet at another easy-to-work place other than the embankment, attach or sow the plant to grow it, and plant the plant roots in the nonwoven layer to some extent. After stretching, the plant-carrying nonwoven fabric sheet can be transported to a bank and laid.

The method of the present invention can be applied to embankments such as rivers, artificial waterways, canals, lakes and marshes, and is not flooded at normal water levels. However, when the water level rises temporarily due to heavy rain or a typhoon, etc. In addition to front slopes 3 and front steps 4 that may be submerged by running water, apply to the back slopes 3 'and back steps 4' on the opposite side of the embankment, top 2 and low-water river banks 6 it can. When the method of the present invention is applied to the front slope 3 or the front small step 4, as described above, it is difficult for rainwater during precipitation to enter the embankment, and does not allow the embankment soil to flow out during drainage after flooding. ,
Do not soften the levees. On the other hand, also when applied to the back slope 3 ′, the back small step 4 ′, or the top end 2, the rainwater at the time of precipitation hardly penetrates into the embankment, so that the embankment is not softened. That is, if the entire embankment is vegetated by the method of the present invention, the embankment is unlikely to be softened. In addition, the method of the present invention is also applied to the slopes and small steps of river banks (those not depending on embankment), such as rivers, artificial waterways, canals, lakes and marshes, which are in the same situation as the surface slopes 3 and small steps 4 of the embankment. it can.

FIG. 2 shows a nonwoven fabric sheet 10 that is embanked with earth and sand 11.
FIG. 2 is a cross-sectional view schematically showing a state in which a soil 13 is placed on a nonwoven fabric sheet 10, a plant 13 is grown, and its roots 14 are stretched in the embankment earth and sand 11. FIG.
Fig. 1 shows an example in which a slope and a small step of a river embankment are protected by the method of the present invention. That is, the nonwoven fabric sheets 10a, 10b, 10c and 10d are arranged in this order from the lower part of the embankment.
Before placing each nonwoven fabric sheet on the embankment soil, it is desirable to apply fertilizer and water to the embankment surface.
After laying the nonwoven sheet 10a, the nonwoven sheet 10a
Superimpose the lower end of the nonwoven fabric sheet 10b on the upper end of
If necessary, both are fixed to the embankment body soil 11 with appropriate fixing means (for example, wooden or metal studs) 15, and then the nonwoven fabric sheet 10c thereon is similarly laid. Further, if necessary, a soil (not shown) is placed on each non-woven fabric sheet, and seeding or pasting is performed.
If it is stretched within 1, the embankment will be greened and protected. In addition, you may use the nonwoven fabric sheet 10a-10d which supports the plant which has already been grown to some extent.

[0017]

According to the method of the present invention, a nonwoven fabric sheet having a high density and having a greater permeability in the horizontal direction than in the thickness direction is laid on the embankment surface, so that rainwater during precipitation hardly enters the embankment, and When drainage is performed after flooding, the embankment soil and sand are not allowed to flow out, so that softening of the embankment can be prevented. In addition, since the roots of the plant are stretched in the embankment soil via the nonwoven fabric layer, the embankment protected by the method of the present invention is not easily peeled off even when exposed to running water. Furthermore, when the plant height of the plant is 5 to 50 cm, the height of the plant is reduced by running water during flooding, and the entire surface of the nonwoven fabric is covered, so that water hardly penetrates into the embankment,
In addition, the plant height acts as resistance against running water, and the flow velocity near the surface of the nonwoven fabric sheet is reduced, so that scouring is not performed.

Example 1 Polyethylene / polypropylene core / sheath composite fiber having a fineness of 6 denier 60% and polyethylene / polyethylene having a fineness of 18 denier /
A fiber web was obtained by blending 40% of a polypropylene core-sheath type composite fiber with a card method. Thereafter, by needle punching and fusing only the polyethylene component of the composite fiber, the basis weight is 225 g / m ² , the thickness is 5 mm, the width is 30 cm,
Length 3 m, fiber density 49.5 m / cm ³ [225 × 10 ^-4 / (6
× 0.5) × 9000 × 0.6 + 225 × 10 ^-4 /(18×0.5)×9000×0.
4] was obtained. Put this non-woven fabric sheet in a wooden box (internal dimensions length = 3m, width = 30cm, depth = 20cm)
On the soil packed in the soil, place the soil on the sheet at a height of about 2 cm, and place Wrangler turf on 15 to ² per square meter.
Seed 0g, cover 1cm more, cure for about 90 days,
The roots of the Wrangler turf were spread well in the soil. The root of the Wrangler turf at this time is about 18 to 20 cm long, penetrating the nonwoven sheet and invading the soil,
The length of the plant was about 40 cm. Subsequently, as shown in FIG. 4, the wooden box 21 thus prepared was mounted on a waterway experiment device 22 made of a synthetic resin having a transparent side surface, and fixed by a block 23. Next, under the conditions of a water flow rate of about 400 liters / second, an average flow velocity of about 3 m / second, and an average flowing water height of about 60 cm, water was flowed from the inlet 24 in the direction of arrow A for 72 hours to perform a strength test. The velocity used in this experiment is the maximum velocity expected to occur near the embankment during floods in the middle river area of a relatively large river. The period during which the embankment is exposed to running water due to flooding is generally at most about 72 hours.

Example 2 The same nonwoven fabric sheet as in Example 1 was placed on the soil packed in the same wooden box as in Example 1, and about 2
After placing the soil of cm, the nosiba was solidly spread on the soil and cured for about 90 days, and the root of the nosiba was fully spread in the soil. At this time, the roots of the Japanese fever have a length of about 10 cm, penetrate the non-woven fabric sheet and enter the soil.
The plant height was about 10 cm. Hereinafter, a strength test was performed in the same manner as in Example 1.

Comparative Example 1 A strength test was performed in exactly the same manner as in Example 1 except that the nonwoven fabric sheet was not used. The root of the Wrangler turf was about 20 to 22 cm, and the length of the plant was about 40 cm.

Comparative Example 2 A strength test was performed in exactly the same manner as in Example 2 except that the nonwoven fabric sheet was not used. In addition, the roots of the nosy grass were about 12 cm, and the length of the plant height was about 10 cm.

Comparative Example 3 A fiber web was obtained by blending 100% of a polyethylene / polypropylene core-sheath type composite fiber having a fineness of 18 denier by a card method. Thereafter, by needle-punching treatment and fusing only the polyethylene component of the composite fiber, the basis weight is 150 g / m ² , the thickness is 8 mm, the width is 30 cm, the length is 3 m, and the fiber density is 9.4 m / cm ³ [150 × 10 ^−4. /(18×0.8)×9000]. A strength test was performed in exactly the same manner as in Example 1 except that this nonwoven fabric sheet was used. In addition, the root of the Wrangler turf has a length of about 17 to 19 cm and penetrates the nonwoven fabric sheet, and the length of the grass is about 40 cm.
Met.

Example 3 Polyethylene / polypropylene core-sheath type composite fiber having a fineness of 18 denier and 60% polyethylene / polypropylene having a fineness of 6 denier
A fiber web was obtained by blending 40% of a polypropylene core-sheath type composite fiber with a card method. Thereafter, by needle-punching treatment and fusing only the polyethylene component of the composite fiber, the basis weight is 180 g / m ² , the thickness is 10 mm, and the width is 3
0 cm, length 3 m, fiber density 16.2 m / cm ³ [180 × 10 ^-4
/(18×1.0)×9000×0.6 + 180 × 10 ^-4 /(6×1.0)×9000
× 0.4]. A strength test was performed in exactly the same manner as in Example 1 except that this nonwoven fabric sheet was used. The root of the Wrangler turf penetrated about 17 to 19 cm, and the length of the plant was about 40 cm.

Example 4 40% polyester fiber of 3 denier fineness, 1.5 fineness
A fiber web was obtained by mixing 40% of denier polyester fiber and 20% of undrawn polyester fiber of 5 denier fineness by a card method. Thereafter, the undrawn polyester fiber is fused to obtain a basis weight of 500 g / m ² , a thickness of 1.1 mm, a width of 30 cm, a length of 3 m, and a fiber density of 1800 m / m.
cm ³ [500 × 10 ^-4 /(3×0.11)×9000×0.4+500×10 ^-4
/(1.5 × 0.11) × 9000 × 0.4 +500 × 10 ^-4 / (5 × 0.11)
× 9000 × 0.2]. A strength test was performed in exactly the same manner as in Example 1 except that this nonwoven fabric sheet was used. The root of the Wrangler turf had a length of about 14 to 16 cm and penetrated the nonwoven fabric sheet, and the length of the plant was about 40 cm.

Comparative Example 4 25% polyester fiber having a denier of 3 denier and a denier of 1.5
A fiber web was obtained by mixing 50% of a denier polyester fiber and 25% of an undrawn polyester fiber having a fineness of 5 denier by a card method. Thereafter, the undrawn polyester fibers are fused to obtain a basis weight of 48 g / m ² and a thickness of 0.1 g / m ² .
1mm, width 30cm, length 3m, fiber density 2016m / cm ^{3
[48 × 10 -4 / (3} × 0.01) × 9000 × 0.25 + 48 × 10 -4 /(1.5
× 0.01) × 9000 × 0.5 + 48 × 10 ^-4 / (5 × 0.01) × 9000 ×
0.25]. Except that this nonwoven fabric sheet was used, an attempt was made to carry out a strength test in exactly the same manner as in Example 1, but the root hardly penetrated, and the strength test could not be carried out.

Results of Strength Test The results of the strength tests of Examples 1 to 4 and Comparative Examples 1 to 4 were visually evaluated based on the following criteria A to F. (A) Leaf outflow was observed locally. (B) Local scouring of the root was observed. (C) Cracks in the turf layer due to scouring were found locally. (D) The root layer was turned up over a wide range. (E) The sliding of the root layer was observed over a wide area. (F) Lifting from the bottom surface of the turf was observed over a wide area. The results are shown in Table 1 below, and those having practicality are those of Examples 1 to 4 in which the evaluation is (A) or (B), and Comparative Examples 1 to 4 in which the evaluation is (C) to (F). Four cannot be used in practice.

[0027]

[Table 1] Example Evaluation Example 1 A Example 2 A Example 3 B Example 4 B Comparative Example 1 C Comparative Example 2 F Comparative Example 3 C Comparative Example 4 It was impossible.

Although the present invention has been described with reference to specific embodiments, the present invention is not limited to these embodiments.

[0029]

According to the method of the present invention, since the plants do not flow out even when exposed to relatively fast running water during flooding as well as during precipitation, no repair is required after flooding or simple. The dike can be protected to the extent that it can be restored. As described above, since the embankment can be protected only by combining the high-density nonwoven sheet and the plant, the construction method is easy, cheap, and aesthetically excellent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a typical structure of an embankment.

FIG. 2 is a cross-sectional view schematically showing one embodiment of the method of the present invention.

FIG. 3 is a cross-sectional view schematically showing one embodiment in which a slope, a small step, and a top end of a river embankment are protected by the method of the present invention.

FIG. 4 is an explanatory view of an experimental device for examining the effect of the method of the present invention.

[Explanation of symbols]

 10 ... non-woven fabric sheet 11 ... embankment earth and sand 12 ... guest soil 13 ... plant 14 ... root

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kazuo Uga 2-8-10 Toranomon, Minato-ku, Tokyo Inside the National Land Development Research Center (72) Inventor Takuo Ohori 2--14 Sotokanda, Chiyoda-ku, Tokyo No. 5 Inside Japan Vilene Co., Ltd. (56) References JP-A-63-70718 (JP, A) JP-A-5-140919 (JP, A)

Claims (1)

(57) [Claims] 1. A fiber density of 10 to 20 laid on the surface of a dike
00m / cm ³ of the nonwoven fabric roots of plants vegetation on a layer of, and characterized in that stretched through the nonwoven layer to the embankment sediment embankment protection method embankment.