JP2006274742A - Erosion preventing material and erosion preventing construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an erosion preventing material and an erosion preventing construction method for protecting a slope and achieving greening by maintaining erosion preventing function and anti-frost-heaving function of the earth for a long time by tight adhesion to the slope in a wrapping manner. <P>SOLUTION: The sheet 3 is made by mixing a plurality of kinds of fibers having different levels of decomposition rate. One of the kinds of fibers comprising the sheet has a water absorbing property, and the rate of decomposition is adjusted to have the erosion preventing function for at least half a year. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an erosion-preventing material and an erosion-preventing method. For example, sheet-like thin cotton is laminated and integrated on a net or mat made of polyethylene fiber, palm fiber, palm hair, jute, wood wool or the like. TECHNICAL FIELD The present invention relates to a erosion prevention material that has been made into an erosion and a erosion prevention method using the erosion prevention material.

  Conventionally, in order to protect the slope surface layer, a vegetation substrate integrated by laminating a net or mat and sheet-like thin cotton and bonding them together with a water-soluble adhesive or sewing them with a thread has been provided. It was used. However, the former vegetation substrate has a problem that a large amount of water-soluble adhesive is required and it takes time to dry. Further, when thin cotton is attached with a thread, there is a problem that the thin cotton does not leave the net or the mat after construction.

  Therefore, in Patent Document 1, a net or mat and a sheet-like thin fiber are entangled so that a very small amount of adhesive is used or no net or mat and sheet-like thin are used. It is described that cotton is integrated. By using the vegetation substrate described in Patent Document 1, thin cotton is not accidentally peeled off from the net or mat before construction, and after construction, the thin cotton is quickly detached from the net or mat, Cotton can be brought into close contact with the slope surface soil.

And, by using the vegetation base so that the thin cotton wraps the surface soil on the slope, it is difficult for rain wind to directly hit the slope until the plant grows and covers the slope. The slope can be protected by preventing the surface soil from being washed away by rain and freezing in winter. That is, the vegetation substrate of Cited Document 1 can be used as a slope erosion preventing material.
JP 2000-175556 A

  However, even when the conventional method or the invention described in Patent Document 1 is used, the protective effect of thin cotton only has to be exhibited for a short period until the vegetation grows. Made of fiber, this was corroded and decomposed early in the months after construction. Therefore, in the unlikely event that plant growth is poor and it takes a considerable amount of time to plant the slope, there may be a situation in which the thin cotton does not perform the function of protecting the slope before achieving the slope planting. It was. The slopes could not be protected by thin cotton or plants, and erosion due to rain, surface soil runoff, or surface soil runoff due to frost heaving in winter.

  Therefore, it is conceivable to slow down the decomposition time of the thin cotton by using a fiber having corrosion resistance as a fiber constituting the thin cotton. Generally, a fiber having corrosion resistance is necessary for the thin cotton. Since properties such as water absorption are not sufficient, not only can erosion prevention and frost heaving prevention not be sufficiently performed, but also there is a problem that it is difficult to promote seed germination growth.

  In recent years, consideration for ecosystems has been screamed, and greening by seeds flying from surrounding plants (including seeds falling directly from plants) has started to be considered. Took time and needed to protect the slope until the plant grew. However, if the slope is physically protected, the introduction of surrounding plants may be hindered, and it has been desired to establish a method for achieving both the introduction of the surrounding vegetation and the slope protection.

  The present invention has been made in consideration of the above-mentioned matters. The purpose of the present invention is to maintain the soil erosion prevention function and frost heave prevention function over a long period of time by closely contacting the slope. An object of the present invention is to provide an erosion prevention material and an erosion prevention method capable of protecting and achieving greening.

  In order to achieve the above object, the erosion preventing material according to claim 1 is a sheet formed by mixing a plurality of types of fibers having different decomposition rates, and at least one of the fibers constituting the sheet is water-absorbing. And the sheet disassembly speed is adjusted so as to have an erosion prevention function for at least half a year.

  Specifically, it is suitable for promoting the growth of plants that the sheet is formed by mixing fibers having water absorption at a ratio of at least 30%, preferably 50% or more. The decomposition rate is adjusted so that at least 50% or more, more preferably 70% or more of the sheet constituent fibers remain without being decomposed when one year has passed since the construction, although there is a difference depending on site conditions. It is suitable for surely preventing erosion.

  The sheet is preferably a sheet-like thin cotton (not a cotton, but a thin cotton-like one), but may be a nonwoven fabric or paper. This sheet has a strength that does not hinder the sprouting and rooting of plants, and has an erosion prevention function by setting the average thickness to 0.1 to 10 mm, preferably 0.5 to 5 mm. Although it has it, it makes it easy to let the plant take root on the ground.

  It is desirable that a soil conditioner, water retention material, and fertilizer are attached to the back surface of the sheet, and seeds for achieving slope greening may be attached. For example, plant seeds such as wild grass species such as Japanese pampas grass, mugwort, and meadow grass, tree species such as weasel hagi and yamahagi, plant species such as tall fescue, Bermudagrass, creeping red fescue, red top and white clover are attached. It is desirable that In addition, for example, seeds of grasses such as perennial ryegrass and Italian grass, and seeds of pioneering plants such as nurde, akamegashiwa, yashabushi and nemony may be used. These seeds may be placed on the entire surface of the sheet to aim for a wide range of greening. However, an area where seeds do not exist is provided in a partial arrangement, and seeds flying from surrounding plants are grown in that area. If it is within the range, it is preferable because surrounding plants can be actively introduced.

  The decomposition rate of the sheet is preferably adjusted by mixing biodegradable fibers made of plant materials with relatively excellent corrosion resistance, but also metal fibers, animal fibers, palm fibers, bamboo fibers, etc. The vegetable fiber may be used. In any case, it is desirable that the fiber constituting the sheet is finally completely decomposed. In addition, it is desirable to adjust characteristics such as sheet flexibility and heat retention by mixing a plurality of types of fibers.

  The net or mat and the sheet may be laminated, and the net or mat and the sheet may be integrated by causing the fibers of the sheet to be entangled with the fibers of the net or mat. The net or mat and the sheet may be bonded with a small amount of water-soluble adhesive. It is desirable that the sheet is configured so as to be quickly detached from the net or mat and to adhere to the ground surface by absorbing rainwater or the like. In addition, the net or mat and the sheet are laminated and pressed between the rollers to press the sheet or fiber so that the sheet or fiber is entangled with the net or mat and the net or mat and the sheet are integrated. It is desirable that Furthermore, it is desirable that the fiber of the sheet is raised on the net or mat side to be entangled with the net or mat fiber by blowing air from the sheet side or sucking air from the net or mat side. .

  The fiber may be a mixture of rayon and polylactic acid fiber (Claim 2). Polylactic acid fiber is a biodegradable fiber made from lactic acid obtained from starch such as corn, and generally has higher corrosion resistance than rayon.

  Moreover, you may have an upper net connected with the said net | network or mat | matte so that it may be located on the said net | network or mat | matte. That is, the upper net may be arranged in a state of floating from the net or the mat to form a seed capturing area for capturing the seeds of surrounding plants on the sheet or the mat. In this case, it is desirable that the upper net is made of a fiber that is easily contracted by heat.

  The erosion prevention method according to claim 3 is characterized in that the erosion prevention material according to claim 1 or 2 is fixed in a state where the sheet is laid so as to contact the ground surface.

  In the erosion prevention material according to claim 1, the ground surface is covered with the sheet, and it is possible to surely prevent the rainwater from directly hitting the slope, so that the erosion of the slope due to rain and the surface soil can be prevented. Can prevent runaway. Moreover, since the temperature change of the ground surface due to the temperature change of the outside air temperature can be reduced, it is possible to prevent the surface soil from being washed away by freezing in the winter. Since the sheet is a sheet-like thin cotton, it can be easily adapted to the unevenness of the surface soil, but this sheet is a non-woven fabric in order to stabilize the shape of the erosion preventing material before construction. It may be. Further, when the sheet is paper, handling of the erosion preventing material before construction can be further facilitated.

  The sheet is mixed with a plurality of fibers having different decomposition rates, so that the decomposition rate is adjusted. Therefore, until the greening of the surface soil of the slope can be achieved, that is, for at least half a year (ie, Until the plant seeds settle on the slope and firmly root, the slope can be protected. Further, since the fibers constituting the sheet are mixed, it is difficult to be affected by the characteristics of the fibers having corrosion resistance. That is, in general, the fiber having corrosion resistance does not have sufficient water absorption, but since at least one of the fibers constituting the sheet has water absorption, water necessary for germination and growth of the plant is obtained. It can be secured by a sheet.

  Similarly, by mixing a plurality of types of fibers that are different in sheet flexibility and heat retention, it becomes easy to adjust the characteristics. In other words, since the sheet is formed by mixing a plurality of types of fibers having different decomposition rates, the sheet can protect the slope for a sufficiently long period of time until the plant grows to achieve the greening of the slope. The decomposition speed of the sheet can be adjusted to the extent, and an environment in which plants can easily grow can be prepared by the sheet. Further, since the fibers constituting the sheet eventually decompose and return to the soil, the sheet can be used as a nutrient by being absorbed by the plant without being disturbed by the sheet.

  When a soil conditioner, water retention material, and fertilizer are attached to the back surface of the sheet, the state of the sloped surface soil can be made suitable for plant growth. In addition, when seeds are attached to the back side of the sheet at this time, the sheet adheres to the ground surface so as to cover the seeds, so that germination and growth of the seeds are ensured and the establishment is improved. . Furthermore, it is preferable to use, for example, wild grass species such as Japanese pampas grass, mugwort and meadow grass, pasture species such as perennial ryegrass and Italian grass, and seeds of pioneering plants such as nurde, red-crowned wrinkles, chalcedony and nemony. This can prevent adverse effects on the ecosystem of surrounding plants. That is, it is preferable to employ annual grasses or short-lived grasses such as the above-mentioned 2 species as pasture species because the pasture species have a fast decline period and do not inhibit the growth of surrounding plants. Introducing the above-mentioned pioneer plants is preferable because the speed of vegetation transition increases and vegetation similar to surrounding vegetation can be restored earlier. In this case, the erosion preventing material can be referred to as a vegetation base.

  When the net or mat and the sheet are laminated and the net or mat and the sheet are integrated by entwining the fiber of the sheet with the net or the fiber of the mat or using a water-soluble adhesive The rain water fall speed can be reduced to some extent by hitting the net or the mat with rain water.

  Also, when the net or mat and sheet are stacked and pressed between the rollers to press the fiber of the sheet entangled with the net or mat, the thread is sewn with a thread. The sheet is not partially fixed, and the sheet is integrated on the entire surface of the net or the mat. Therefore, they do not come off unexpectedly before construction. After the construction, the sheet absorbs rainwater and the like to increase its flexibility and become heavier, so that the sheet can be quickly detached from the net or the mat and can be in close contact with the ground surface.

  Further, before the pressure is applied by the roller, air is blown from the sheet side or air is sucked from the net or the mat side, whereby the sheet is raised on the net or the mat side to be entangled with the net or mat fibers. If it is left, it is desirable to ensure that the fibers are entangled with the net or the mat.

  When the fiber is a mixture of rayon and polylactic acid fiber (Claim 2), since the rayon has not only water absorption but also flexibility, the sheet is processed so that the sheet wraps the slope. The sheet can be brought into close contact with the surface, and this sheet can prevent drying on the surface of the slope. In addition, the polylactic acid fiber not only has flexibility like rayon but also has a slower decomposition rate than rayon. Therefore, mixing the polylactic acid fiber can reduce the decomposition rate of the sheet. That is, by adjusting the mixing ratio of rayon and polylactic acid fiber, it is possible to easily form a sheet capable of maintaining a good environment for a necessary period for the plant to germinate and grow.

  You may have an upper net connected with the said net or a mat so that it may be located in the upper part of the said net or a mat. That is, the upper net is arranged in a state of floating from the net or the mat to form a three-dimensional structure, and a seed capturing area for capturing the seeds of surrounding plants on the sheet or the mat is formed. Greening with the seeds of surrounding plants that have fallen or fallen into can be performed. Since the upper net is arranged in a state where it floats from the net or the mat, the upper net can suppress the drop speed of the seeds so that the seeds can easily stay in the seed trapping region. Moreover, since this upper net | network can function also as a windbreak, it can protect so that the seed capture | acquired by the seed capture | acquisition area may not be blown off by a wind.

  In addition, when the upper net is made of a fiber that easily contracts due to heat, the fiber constituting the upper net after construction contracts due to solar heat or the like to keep its tension high, and the upper net floats off the slope Can keep you. The upper net is formed by chain-knitting monofilaments made of polyethylene (PE) -based synthetic resin as an example of a fiber that is easily contracted by heat.

  According to the erosion prevention method according to the third aspect of the invention, the sheet can be protected by the sheet being in close contact with the slope and preventing the erosion and frosting of the slope by the erosion prevention material. And by the protected slope, it is possible to prepare an environment in which plant seeds can easily grow.

  FIGS. 1 and 2 are views showing an erosion preventing material 1 according to a first embodiment, in which FIG. 1 is a perspective view showing a configuration of the erosion preventing material 1, and FIG. 2 is a diagram for explaining a manufacturing method of the erosion preventing material 1. It is. In these figures, 2 is a net, 3 is a sheet, and in this embodiment is a sheet-like thin cotton. In addition, the thin cotton here does not mean a thin cotton, but means a thin cotton-like material made of a material as described later, for example. Further, the sheet is not limited to the thin cotton 3 and may be a nonwoven fabric or paper.

  The net 2 is a warp yarn 2b formed by knitting a weft yarn 2a made of a flat yarn made of, for example, polyethylene (PE) -based synthetic resin, and a monofilament made of, for example, PE-based synthetic resin, which goes straight to the weft yarn 2a. The weft yarn 2a is formed by knitting between the warp yarns 2b in a zigzag manner.

  In the following description, an example in which the thin cotton 3 is attached to the net 2 using each embodiment will be described. Instead of the net 2, fluffing on the surface made of palm fiber, palm hair, jute or the like is shown. A mat may be used. Further, the present invention is not limited to the net 2 or the mat and the sheet (thin cotton 3) being integrated, but the thickness of the cotton-like material constituting the sheet can be changed, the nonwoven fabric or the paper-like The net 2 or the mat may be omitted by using a material having a stable shape such as a material.

  On the other hand, the thin cotton 3 shown in the present embodiment has such a degree of flexibility that it can be easily adhered to the surface of the uneven construction target soil, and is attached to the lower surface of the net 2. A plant growth base 4 such as an agent and a fertilizer and a plant seed 5 are attached. The fiber constituting the thin cotton 3 is a mixture of two or more kinds of fibers having different decomposition rates, and has sufficient corrosion resistance and water absorption.

  Thin cotton 3 is made of fiber made of rayon, a material with excellent water absorption, and fiber made of polylactic acid fiber (for example, biodegradable plastic such as “Lactron”), which is a corrosion-resistant material. It is a mixture of 50% each. By changing the mixing ratio, the thin cotton 3 can be decomposed at a desired decomposition rate and have a desired water absorption. However, the material of each fiber constituting the thin cotton 3 is not limited to rayon and polylactic acid fiber.

  That is, the water-absorbing fiber can be not only rayon but also various fibers such as palm fiber. As the corrosion-resistant fiber, biodegradable plastics other than polylactic acid fiber can be used. Animal fibers such as palm fibers or strong plant fibers such as palm fibers or bamboo fibers may be used. Furthermore, it is also possible to use metal fibers and the like. In any case, it is desirable that the decomposition rate of the thin cotton 3 is such that it will not be completely decomposed even after one year has passed since construction, and at least half a year or more, it will be difficult for the wind to hit the slope directly. It is. However, it is preferable that all the fibers constituting the thin cotton 3 are finally completely degraded by microorganisms.

  In addition to these characteristics, it is desirable that the thin cotton 3 has a flexibility that can be flexibly deformed in accordance with the irregularities on the surface of the construction target soil. In this respect as well, rayon is excellent in flexibility and water absorption, and the thin cotton 3 formed by mixing 50% of the rayon is closely attached so as to wrap around the surface of the construction target soil, and the surface of the construction target soil. The water required for germination and growth of seeds can be ensured by water retention in On the other hand, polylactic acid fiber has a slower decomposition rate than rayon, so thin cotton 3 can protect the surface of the construction target soil for a long period of time. Rapid temperature changes on the surface of the target soil can be suppressed.

  As shown in FIG. 2, the erosion-preventing material 1 is formed between a pair of upper and lower rollers 10 and 11 in a state where the weft 2a and warp 2b constituting the net 2 are laminated so that the fibers 3a of the thin cotton 3 are entangled. It is formed by pressing through. A nozzle 12 is formed above the vicinity of the rollers 10 and 11 and blows air 13 from the thin cotton 3 side. Accordingly, before the net 2 and the thin cotton 3 are pressed by the rollers 10 and 11, the fibers 3 a of the thin cotton 3 can be largely raised on the net 2 side, and the fibers 3 a are reliably entangled with the net 2. Can be. Needless to say, the raising process by the nozzle 12 may be omitted to simplify the manufacturing process of the erosion preventing material 1.

  The adhesion of the plant growth base 4 and the plant seed 5 to the surface of the thin cotton 3 is, for example, sprayed on the surface of the thin cotton 3 and humidified by spraying the plant growth base 4 and the plant seed 5 coated with a water-soluble paste. After applying pressure, or after spraying the plant growth substrate 4 and the plant seed 5 on the surface of the thin cotton 3, a water-soluble paste (so-called foam adhesive containing a large number of bubbles) is applied, or the thin cotton After applying a water-soluble paste (foam adhesive) to the surface of 3, it can be carried out by any method such as spraying the plant growth base material 4 or the plant seed 5. Further, the adhesion of the plant growth base material 4 and / or the plant seed 5 to the thin cotton 3 may be omitted, or the adhesion of the net 2 and the thin cotton 3 using a water-soluble paste material may be omitted.

  FIG. 3 is a diagram for explaining another method related to the production of the erosion preventing material 1. As shown in FIG. 3, a vacuum device 14 is provided below the vicinity of the rollers 10 and 11, and before passing the laminated net 2 and the thin cotton 3 on the sheet between the rollers 10 and 11, the net 2 side The air 13 is sucked from the fiber 3 so that the fibers 3a of the thin cotton 3 may be raised on the net 2 side.

  FIG. 4 shows an erosion prevention method for protecting the slope N using the erosion prevention material 1 manufactured as described above, and FIG. 5 shows the state of the erosion prevention material 1 after laying on the slope N. FIG.

  As shown in FIG. 4, when the erosion preventing material 1 is laid on the slope N, the erosion preventing material 1 is laid upside down from the posture shown in FIGS. At this time, since the slope N has irregularities, a gap may be formed between the slope N and the erosion preventing material 1, but the adjacent erosion preventing materials 1 can be arranged without a gap, for example, reverse U The erosion preventing material 1 is fixed to the slope N by using a retaining skewer 15 or the like on the character.

  Fig. 5 (A) is a diagram showing the state of the erosion preventing material 1 and slope N immediately after construction, Fig. 5 (B) is a diagram showing the state when rainfall occurs after construction, and Fig. 5 (C) is after construction. It is a figure which shows the state of the construction site when several months pass. As shown in FIG. 5 (A), a gap is formed between the slope N and the erosion prevention material 1 immediately after the construction, but as shown in FIG. 5 (B), the thin cotton 3 absorbs rainwater due to rain. When it becomes supple and becomes heavy, it can be separated from the net 3 to adhere to the ground surface so as to cover the plant growth substrate 4 and the plant seed 5, and germination of the plant seed 5 can be promoted early after construction. . In addition, the rooting is ensured and the survival is good.

  As shown in FIG. 5 (C), even if a period of several months has passed after the construction, the thin cotton 3 can continue to be protected so as to wrap the surface of the slope N, and the surface soil of the slope N throughout the whole period. Can be protected from rain and wind. In addition, since the thin cotton 3 has an appropriate water retention capacity, it is possible to secure moisture necessary for the growth of the plant seed 5 and to protect it from drying. That is, the plant seed 5 can be reliably grown.

  In addition, the thin cotton 3 can capture and trap the flying seeds and falling seeds on the fiber. In other words, by forming a seed capture area that captures flying seeds and fallen seeds with thin cotton 3, it is possible to promote greening using the seeds of surrounding plants, and to make the original ecosystem at the construction site as early as possible Can be recovered. Moreover, although the example which attaches the plant seed 5 to the said thin cotton 3 is shown in the above-mentioned Example, by not attaching the plant seed 5 to the thin cotton 3, greening using only the seed of a surrounding plant is performed. Is possible, and there is no risk of threatening the ecosystem at the construction site.

  Furthermore, in the above-described embodiment, the thin cotton 3 of this embodiment is provided with a plant growth base material 4 such as a water retaining material, a soil conditioner and a fertilizer on the back surface. This can be held in a state where 4 is brought into close contact with the surface of the soil to be constructed. That is, the surface soil condition can be made an environment suitable for plant growth.

  FIG. 6 is a diagram showing the results of a field test for verifying the effect of the erosion preventing material 1 of the present invention, in which a thin cotton 3 of 100% rayon (hereinafter referred to as a thin cotton 3A for distinction) is formed. An erosion prevention material 1 according to the present invention in which a thin cotton 3 formed by mixing 50% of rayon and 50% of polylactic acid fibers (hereinafter referred to as thin cotton 3B for distinction) is formed. It is a figure which compares and shows the measurement result when a field test is implemented in comparison.

  The graph shown in FIG. 6 shows that the erosion-preventing material 1 made of both thin cottons 3A and 3B is laid on the same slope N, and the slope of the slope is stable at each time point after 209 days (after about 7 months). It is to judge the situation. The thin cotton 3A is already corroded when 169 days (about 5 months) have passed since the construction, and almost half of the thin cotton 3A is bare, whereas the thin cotton 3B is at the same time. It is not corroded at all, and almost 100% of the slope N can be covered.

  In FIG. 6, 20 shows the outside air temperature of a construction site, 21 and 22 show the temperature of the ground surface in the lower surface of the said thin cotton 3A, 3B. Looking at the temperature change in the range shown in FIG. 6, the outside air temperature 20 at the construction site changes in the range of −3 to + 25 ° C., but the thin cotton formed by mixing 50% rayon and 50% polylactic acid fiber. It can be seen that the temperature change at the slope N covered with 3B can be suppressed within the range of +3 to 18 ° C. On the other hand, the temperature of the slope N covered with the thin cotton 3A of 100% rayon changes in the range of +2 to 25 ° C. This is due to the change of the surface temperature in the bare ground of the slope N (not shown). The same.

  As is clear from the measurement results of the temperature change with time at the lower part of the thin cotton 3A, 3B, the fibers constituting the thin cotton 3 as in the present invention are mixed with a plurality of types of fibers having different decomposition rates. Thus, at least half a year, it is possible to prevent the thin cotton 3 from directly hitting the slope N with rain and to protect it from erosion due to rain. In addition, the thin cotton 3B obtained by mixing the fiber made of rayon and polylactic acid fiber is excellent in heat retention. For example, even when the outside air temperature is lowered to -3 ° C, the lower portion of the thin cotton 3B has + 3 ° C or more. The temperature can be kept. Accordingly, the thin cotton 3B can effectively prevent winter freezing and effectively prevent soil runoff associated with the surface soil of the slope N being frozen.

  FIG. 7 is a view showing a configuration of an erosion preventing material 30 according to the second embodiment of the present invention. The members denoted by the same reference numerals as in FIGS. 1 to 6 are the same or equivalent members, and thus detailed description thereof is omitted. In FIG. 7, 31 is an upper net connected to the net 2 so as to be positioned above the net 2, 32 is an intermediate closing thread that connects the upper net 31 to the net 2, and 33 is an intermediate closing thread 32. An accommodating portion 34 formed between the nets 2 and 31 by providing a non-closed portion is a fertilizer bag accommodated in the accommodating portion 33.

  The upper net 31 is formed, for example, by knitting a weft 31a formed by chain-knitting a monofilament made of PE-based synthetic resin, and by knitting a monofilament made of, for example, PE-based synthetic resin that goes straight to the weft 31a. In this embodiment, the upper net 31 can be arranged at a predetermined height position above the net 2 by connecting the warps 2b and 31b with the intermediate closing thread 32.

  The inner closing thread 32 forms, for example, a mesh body 30a having a double knitting structure by connecting the warps 2b and 31b with an appropriate interval (for example, one interval). Further, the accommodation portion 33 is formed by leaving a portion where the middle closing yarn 32 does not connect the warp yarns 2b and 31b in the lateral direction. The present invention is not limited to connecting the nets 2 and 31 with the middle closing thread 32, and the warp yarns 2b and 31b are knitted at an appropriate interval (for example, one interval). It is also possible to connect them in such a way.

  The upper net 31 knitted with monofilaments made of PE-based synthetic resin has a higher heat shrinkage rate than the net 2 knitted with flat yarns made of the same PE-based synthetic resin. A double knitted structure can be easily formed. That is, when attaching the thin cotton 3 to the lower surface of the net body 30a (particularly the net 2) or attaching the plant growth base 4 or the plant seed 5, the thin cotton 3 is heat-sealed to the net body 30a. It is necessary to apply heat for drying the adhesive or heat for drying the adhesive, but the heat can cause the upper net 31 to contract more greatly than the net 2, and thereby the double knitting of the net body 30 a. A structure can be easily formed.

  The difference in heat shrinkage is that the monofilament constituting the upper net 31 is manufactured by extrusion forming processing, whereas the flat yarn constituting the net 2 is formed by stretching while applying heat. It is thought that it is because.

  The fertilizer bag 34 is accommodated in the accommodating portion 33. For example, in the bag 34a formed of a corrosion-resistant nonwoven fabric, nutrients that are eluted little by little are at least several months to several years (this implementation). In the case of the example, it accommodates a super slow-acting fertilizer 34b that is continuously supplied over a long period of 3 to 5 years).

  Although the fertilizer bag 34 of the present embodiment shows an example in which no plant seeds are included, the slope N is greened in the fertilizer bag 34 at an early stage after construction, and the ecosystem of surrounding plants is shown. It may contain seeds of pioneer plants that do not adversely affect the plant. Similarly, a plant growth base material such as a soil improvement material or a water retention material may be accommodated in the fertilizer bag 34.

  The erosion preventing material 30 is fixed by anchors 35 in order from the uppermost fertilizer bag 34 of the erosion preventing material 30 so that the fertilizer bag 34 has a substantially contour line shape. At this time, the upper net 31 is placed in a state where it floats from the slope by applying tension to the upper net 31. In the case of the present embodiment, the fertilizer bag 34 has a diameter of 2 to 3 cm, and a space of 2 to 3 cm is formed between the net 2 and the upper net 31. At this time, since the upper net 31 is slightly contracted compared to the net 2, the net 2 can be slightly slackened even when the upper net 31 is tensioned, and the net 2 is brought to the slope N. Can be along.

  By laying the erosion prevention material 30 configured as shown in FIG. 7 on the slope N, the surface soil of the slope N is covered with thin cotton 3 to protect the soil from erosion and frost heave. Since the plant seed 5 is closely attached to the slope N, germination and growth can be promoted. And the germination growth of the plant seed 5 can be accelerated | stimulated by the plant growth base material 4 attached to the thin cotton 3 in addition to the water retention property which the thin cotton 3 itself has.

  Further, in the erosion preventing material 30 of this embodiment, a seed catching region 36 for catching the seeds of the surrounding plants is formed on the upper surface of the thin cotton 8, and the slope N that takes in the seeds of the surrounding plants is greened. It is. Here, when the peripheral seeds that have come and fallen peripheral seeds (hereinafter simply referred to as seeds) 40 fall on the erosion prevention material 30, they hit the upper net 31 and the net 2, and the falling speed thereof decreases. While absorbing the kinetic energy, the falling direction is dispersed and remains on the surface portion of the thin cotton 3. At this time, the fibers of the thin cotton 3 attached to the back surface of the net 2 are entangled, and the seed 41 is captured by the thin cotton 3 and stays there.

  Although the net 3 and the upper net 31 have such a degree that the seed 40 can pass therethrough, the net 3 and the upper net 31 function as a windbreak so that a strong wind does not directly hit the seed 41 captured by the thin cotton 3. 41 is protected. Moreover, since the seed | capture | captured by the thin cotton 3 can obtain a water | moisture content and a nutrient from the thin cotton 3, it can germinate and grow easily.

  On the other hand, when the fallen seed 40 is an easy-to-roll seed such as an acorn, the surface of the thin cotton 3 may be rolled by receiving wind from the outside without being entangled with the fibers of the thin cotton 3. Conceivable. However, since the upper part is covered with the upper net 31, the seed 40 once dropped moves to the valley side by gravity without being blown off by the wind. Then, like the seed indicated by reference numeral 42, it stays in contact with the small step formed by the fertilizer bag 34. At this time, since the fertilizer bag 34 is arranged in a contour line, even if the seed 42 may roll down the upper surface of the net 2, this can be received by the fertilizer bag 34. The fertilizer bag 34 can supply nutrients to the surrounding seeds including the seeds 42 received thereby.

  As described above, the erosion preventing material 30 of the present embodiment can perform greening by incorporating the seeds 40 of the surrounding plants. Therefore, in the above embodiment, the thin cotton 3 is used as the plant growth base material 4 and the plant seed 5. However, it goes without saying that the attachment of the plant seed 5 to the thin cotton 3 may be omitted. Similarly, when the state of the slope N is good, the attachment of the plant growth substrate 4 to the thin cotton 3 may be omitted.

  In addition, since the upper net 31 in this embodiment is formed of a fiber having a high thermal contraction rate such as a monofilament, the tension applied to the upper net 31 can be kept strong by contracting due to summer heat in the summer after construction. it is conceivable that. That is, the three-dimensional double net structure of the net body 30a can be maintained for a long time.

  And, as already described in detail, the fibers constituting the thin cotton 3 are a mixture of a plurality of types of fibers having different decomposition rates, and one of the fibers has water absorption, and The degradation rate of the thin cotton is adjusted so that the thin cotton will function for at least half a year. Therefore, by using the erosion-preventing material 30 of the present example, the thin N 3 is used for the slope N for a long period (at least half a year or more) until the seeds 5, 41, 42 germinate and grow on the slope N. The surface soil can be protected from erosion and freezing due to rainfall. That is, the planting of the slope N by the plant can be performed reliably.

It is a perspective view which shows the structure of the erosion prevention material which concerns on 1st Example. It is a figure which shows an example of the manufacturing method of the said erosion prevention material. It is a figure which shows another example of the manufacturing method of the said erosion prevention material. It is a figure explaining the erosion prevention construction method using the said erosion prevention material. It is a figure which shows the state after laying the said erosion prevention material. It is a figure which shows the actual measurement data which verifies the effect by the erosion prevention material of this invention. It is a figure which shows the example of the structure of the erosion prevention material which concerns on 2nd Example, and the erosion prevention construction method.

Explanation of symbols

1,30 Anti-erosion material 2 Net (or mat)
3 sheet (thin cotton)
3a Fiber 31 Upper net 36 Seed trapping area 41, 42 Seeds of surrounding plants N Slope

Claims (3)

  A sheet formed by mixing a plurality of types of fibers having different decomposition rates, wherein at least one of the fibers constituting the sheet has water absorption, and at least half a year has an erosion prevention function, An erosion-preventing material characterized in that the decomposition speed of the sheet is adjusted.   The erosion preventing material according to claim 1, wherein the fiber is a mixture of rayon and polylactic acid fiber.   An erosion prevention method according to claim 1 or 2, wherein the erosion prevention material according to claim 1 or 2 is fixed in a state where the sheet is laid so as to contact the ground surface.

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