JP7789339B2 - Vegetation restoration method - Google Patents

Description

The present invention relates to a vegetation restoration method suitable for restoring vegetation on slopes, etc.

A common vegetation restoration method involves laying wire mesh on a slope and spraying on it soil and vegetation substrate to encourage plant growth. The slope protection device described in Patent Document 1 employs wire mesh that is thicker than the generally flat, diamond-shaped wire mesh used to prevent the soil and substrate from being washed away by rainfall or other factors. A substrate wash-off prevention member (fiber rope) is threaded through and stretched within the interior space of the wire mesh. To further enhance the effectiveness of preventing substrate wash-off, instead of the conventional spraying method, the applicant has proposed a slope greening structure in which vegetation bags filled with substrate are placed in the grooves of a thick wire mesh and held in place by a mesh body, and substrate wash-off prevention members (stoppers made of linear bundles of palm fiber, etc.) are arranged in a contoured pattern to prevent the vegetation bags from slipping and the substrate from being washed away (Patent Document 2).

Microfilm of Utility Model Application No. 58-37800 (Utility Model Application No. 59-144050) Japanese Patent Application Laid-Open No. 2006-336193

However, in both the slope protection device of Patent Document 1 and the slope greening structure of Patent Document 2, the substrate flow prevention member (a fiber rope in Patent Document 1, and a stopper in Patent Document 2) is inserted loosely into the internal space of the thick wire mesh (the cross-sectional area of the substrate flow prevention member is one size smaller than the cross-sectional area of the internal space of the wire mesh). As a result, depending on the uneven shape of the ground and the placement of the substrate flow prevention member, there may be areas where the substrate flow prevention member floats significantly above the ground, potentially compromising its effectiveness in preventing substrate flow. Furthermore, this makes the substrate flow prevention member prone to shifting from its fixed position relative to the wire mesh. If this shift causes the substrate flow prevention member to move out of one side of the wire mesh, creating a gap in the wire mesh where no substrate flow prevention member is present, the desired substrate flow prevention effect will not be achieved at least in that area. This necessitates additional work to correct the shift, which creates a corresponding reduction in construction efficiency.

The present invention was made with the above in mind, and its purpose is to provide a vegetation restoration method that can stably maintain a larger number of substrates for a long period of time, while also contributing to improved construction efficiency.

In order to achieve the above object, the vegetation restoration method of the present invention is a vegetation restoration method in which a vegetation restoration device equipped with a wire mesh and a long substrate washaway prevention member is arranged on a slope together with a substrate containing at least one of seeds, vegetation base material, fertilizer, and erosion prevention material, and the wire mesh has a three-dimensional thickness formed by engaging a plurality of wire rods bent in a substantially spiral shape with each other so that the spiral axes of the wire rods are substantially parallel to each other, and each wire rod is configured so that an upper line portion that is curved convex upward and a lower line portion that is curved convex downward are alternately connected to form a substantially spiral shape, and the wire rod in which the substrate washaway prevention member is housed serves as an embracing member that helically embraces the substrate washaway prevention member. The embracing is such that the substrate flow prevention member contacts each of the repeated upper and lower line sections of the wire, the embracing wire has an upper line section that is curved upward and a lower line section that is curved downward, the substrate flow prevention member has a belt-like shape with a roughly rectangular cross section, and the upper line section and the lower line section are arranged to contact or sink into the corners of the substrate flow prevention member, the vegetation restoration device with the substrate flow prevention member held on the unfolded wire mesh is fixed to the slope with anchor pins, and at this time the substrate flow prevention member is arranged so as to follow the contour lines of the slope, a layer of substrate is formed to cover the vegetation restoration device , and the substrate flow prevention member is made of natural fiber such as palm (Claim 1).

In the above-mentioned vegetation restoration method, the upper line portion and the lower line portion may have the same curvature (Claim 2). The embracing wire may be configured to describe a flattened ellipse whose height is smaller than its width when viewed from one end of its spiral axis (Claim 3).

In the above-mentioned vegetation restoration method, the thickness of the substrate washaway prevention member may be smaller than its width (Claim 4).

The present invention provides a vegetation restoration method that can stably maintain a larger number of substrates for a long period of time, contributing to improved construction efficiency.

In other words, in the vegetation restoration method of the invention according to each claim of this application, the embracing wires that make up the wire mesh helically embrace the base material flow prevention member. Therefore, when the wire mesh is aligned with the unevenness of the ground, the base material flow prevention member also roughly follows the unevenness of the ground, thereby enhancing the effectiveness of the base material flow prevention member in preventing base material flow. Furthermore, in the vegetation restoration method of the present invention, the wire mesh and the base material flow prevention member are integrated by the above-mentioned embracing, making it less likely that the base material flow prevention member will accidentally shift from its fixed position relative to the wire mesh. This eliminates the need for tasks such as returning the base material flow prevention member to its fixed position, thereby improving construction efficiency.

In the vegetation restoration method of the invention of claim 1, the lower line of the embracing wire is curved downward in a convex shape, thereby increasing the holding power of the substrate. In other words, the holding power of the substrate is affected not only by the shape of the wire mesh and the presence or absence of a substrate wash-away prevention member, but also by the frictional resistance of the substrate itself against the surface of the construction area. This method reduces the contact area between the lower line of the embracing wire and the surface of the construction area, while also allowing the substrate to be held in the gap below the underline, thereby increasing the frictional resistance of the substrate against the surface of the construction area and, as a result, improving the effectiveness of preventing the substrate from washing away.

In addition, with this construction method, the underline portion of the embracing wire is curved downward, making it less likely that the underline portion will prevent the base material flow prevention member placed above it from coming into contact with the surface of the construction area, thereby increasing the effectiveness of the base material flow prevention member in preventing the flow of base material.

In addition, in the vegetation restoration method of the invention of claim 1, the upper line of the embracing wire is curved upward with a convex shape, so that the width of the upper line narrows toward the top. If the upper line is covered with a base material so that at least the entire upper line is not exposed, then as the base material is eroded or washed away by, for example, a sudden downpour or typhoon, the amount of the upper line exposed to the base material surface increases, and the ability to capture airborne seeds, etc. is strengthened, preventing a significant loss of vegetation restoration capacity.

In the vegetation restoration method of the invention described in claim 2, the shapes of the upper and lower lines are made common, improving productivity and enabling reversible construction by eliminating the need for a front and back side for the wire mesh.

In the vegetation restoration method of the invention of claim 1, by making the substrate flow prevention member approximately rectangular in cross section, the substrate flow prevention member has no front or back (top or bottom), allowing it to be reversibly inserted into the wire mesh. This also makes it easier for the substrate flow prevention member to make surface contact with the ground, improving the effectiveness of preventing substrate flow. Furthermore, for example, when the upper and lower lines of the embracing wire are curved as in claim 1, the substrate flow prevention member effectively fills the space enclosed by the upper and lower lines, and the upper and lower lines contact or sink into the corners of the substrate flow prevention member, making it less likely for the substrate flow prevention member to shift position or come off the wire mesh. This also makes it possible to secure the substrate flow prevention member to the wire mesh without the use of special fastening devices.

In the vegetation restoration method of the invention of claim 1 , by using natural fibers such as palm fibers for the substrate washaway prevention material, its water retention capacity can be improved and it is also expected that it will have a fertilizer effect due to biodegradation.

1A is an explanatory diagram showing a schematic configuration of a vegetation restoration method according to one embodiment of the present invention, and FIG. 1B is a plan view of a vegetation restoration device used in the vegetation restoration method. 1A is a partially enlarged perspective view of the vegetation restoration device, and FIG. 1B is a cross-sectional view of the wire mesh of the vegetation restoration device. 1 is a graph showing the results of an erosion resistance confirmation test conducted on a product that has undergone the vegetation restoration method and a conventional product, with the vertical axis representing the thickness of the substrate and the horizontal axis representing the elapsed time from the start of the test.

Embodiments of the present invention are described below.

As shown in Figure 1(A), the vegetation restoration method in this example involves placing a vegetation restoration device D equipped with wire mesh 1 and substrate washaway prevention members 2, together with a substrate 3, in the construction area R (a slope in this example).

As shown in Figure 2(A), the wire mesh 1 is a diamond-shaped wire mesh (wire lath) with a three-dimensional thickness, made by interlocking multiple wire rods 4 bent in a roughly spiral shape so that the spiral axes of the wire rods 4 are roughly parallel to each other.

In this example, the wire mesh 1 has a width W (see Figure 1(B)) of approximately 2000 mm, a length L (see Figure 1(B)) of approximately 10,000 mm, a mesh size of approximately 56 mm, and a thickness (height) T (see Figure 2(B)) of approximately 16 mm. The wire 4 is made of, for example, zinc-plated iron wire and can be of any thickness depending on the required strength, etc. However, a thickness of less than 1 mm will not be strong enough as a wire mesh, and a thickness of more than 10 mm will make the resulting wire mesh heavy and difficult to install, so a thickness of 1 to 10 mm is preferable. Here, both ends of the wire 4 are knuckled, but they may also be processed using other appropriate processes such as twisting.

As shown in the enlarged view of Figure 1(A) and Figures 2(A) and (B), each wire 4 is configured to form a generally spiral shape with alternating upwardly convex curved upper line portions 4a and downwardly convex curved lower line portions 4b. As shown in Figures 1(A) and 2(B) in particular, when viewed from one end in the spiral axis direction, it forms a flattened ellipse whose height is smaller than its width (the longitudinal cross section has a flattened ellipse shape).

As shown in Figure 1(B), the substrate leakage prevention member 2 is long and is housed within a portion of the wire 4 of the wire mesh 1 so that its spiral axis passes through it. Such a substrate leakage prevention member 2 is preferably made of fibers such as coconut fiber, straw, or palm hair, which are held in the shape of a nonwoven fabric using methods such as chemical bonding, thermal bonding, or needle punching. However, this is not a limitation, and the substrate leakage prevention member 2 may also be made, for example, from a coconut fiber mat (such as a general-purpose mat) cut into a long, thin belt shape.

In addition, in this example, the substrate flow prevention member 2 is belt-shaped (strip-shaped) with a length approximately equal to the width of the wire mesh 1 (approximately 2000 mm) (see Figure 1(B)), and the cross section perpendicular to the longitudinal direction is rectangular, measuring approximately 30 mm (width) x 10 mm (thickness) (see Figure 1(A)). That is, in accordance with the flattened ellipse shape of each wire 4 as described above, the thickness of the substrate flow prevention member 2 is smaller than its width (for example, the thickness is approximately half the width or less). The thickness of the substrate flow prevention member 2 can be adjusted appropriately depending on its material, properties, etc. For example, if the substrate flow prevention member 2 is a belt-shaped member made of palm fiber and the thickness T of the wire mesh is 16 mm, the thickness could be approximately 12 to 13 mm.

In order to ensure stable and reliable retention of the base material flow prevention member 2 by the wire mesh 1, in this example, the wire 4 housing the base material flow prevention member 2 is designed to helically embrace the base material flow prevention member 2 (the base material flow prevention member 2 is in contact with each of the repeated upper line portions 4a and lower line portions 4b of the wire 4). This makes the base material flow prevention member 2 less likely to fall off the wire mesh 1 even if it deteriorates over time, making it easier to maintain its function over a long period of time. Below, the wire 4 helically embracing the base material flow prevention member 2 housed therein may be referred to as embracing wire 4A to distinguish it from other wires 4 that do not house base material flow prevention member 2; however, in this example, the shapes of each wire 4 (embracing wire 4A and other wires 4) are the same.

The substrate 3 contains at least one of seeds, vegetation base material, fertilizer, and erosion prevention material.

Next, we will explain the construction procedure for this example of vegetation restoration method.

(1) First, as shown in Figure 1(A), wire mesh 1 is laid on the slope of the construction area R, and substrate flow prevention members 2 are held by the wire mesh 1 (enveloping wire 4A), and both 1 and 2 are fixed to the construction area R with anchor pins 5. At this time, the substrate flow prevention members 2 are positioned so that they follow the contour lines of the construction area R. This leaves the vegetation restoration device D laid (installed) in the construction area R.

In this example, a base material escape prevention member 2 is inserted into the internal space at one end of the embracing wire 4A of the wire mesh 1, which has been rolled up in advance. An anchor pin 5 is driven into this base material escape prevention member 2 to secure it together with the wire mesh 1 to the construction area R. The wire mesh 1 is then unfolded toward the foot of the slope, and the base material escape prevention member 2 is inserted into the embracing wire 4A of the wire mesh 1 at regular intervals (e.g., 500 mm) from the top of the slope toward the bottom, while being secured with the anchor pins 5. To accommodate the unfolding of the wire mesh 1 as described above, at least some of the anchor pins 5 driven into the portion located closest to the top of the slope (upper side) are slightly larger than the other anchor pins 5, allowing for stronger fixation.

If the wire mesh 1 with the substrate flow prevention members 2 inserted at regular intervals can be rolled up, the substrate flow prevention members 2 may be inserted (attached) into the wire mesh 1 in advance. Even if the wire mesh 1 with the substrate flow prevention members 2 inserted cannot be rolled up, the substrate flow prevention members 2 may be inserted (attached) into the wire mesh 1 in advance if, for example, the wire mesh 1 will be transported in an unfolded state.

(2) A layer of base material 3 is formed by spraying or scattering the base material 3 to cover the vegetation restoration device D (wire mesh 1 and base material washaway prevention member 2) installed in the construction area R.

The vegetation restoration method of this example is completed through steps (1) and (2).

In the vegetation restoration method of this example, the embracing wires 4A that make up the wire mesh 1 helically embrace the base material flow prevention members 2. Therefore, when the wire mesh 1 is aligned with the unevenness of the ground, the base material flow prevention members 2 also follow the unevenness of the ground, thereby enhancing the effectiveness of the base material flow prevention members 2 in preventing base material flow. Furthermore, in the vegetation restoration method of this example, the wire mesh 1 and the base material flow prevention members 2 are integrated by the above-mentioned embracing, making it less likely that the base material flow prevention members 2 will accidentally shift from their fixed position relative to the wire mesh 1. This eliminates the need for tasks such as returning the base material flow prevention members 2 to their fixed position, thereby improving construction efficiency.

Furthermore, the vegetation restoration method of this example basically requires only wire mesh 1, substrate washaway prevention member 2, substrate 3, and anchor pin 5, which reduces the number of components and labor required, making it extremely easy to reduce construction costs.

Furthermore, in this example of vegetation restoration construction method, the long substrate flow prevention members 2 are arranged so as to roughly follow the contour lines and are fixed together with the wire mesh 1 by anchor pins 5 so that they are in contact with the surface of the construction area R. This means that the substrate flow prevention members 2 act as a buffer material, and the wire mesh 1 as a whole easily fits the unevenness of the surface of the construction area R.

In this example, the vegetation restoration method increases the holding power of the substrate 3 by making the underline 4b of each wire 4, including the embracing wire 4A, convexly curved downward. In other words, the holding power of the substrate 3 is affected not only by the shape of the wire mesh 1 and the presence or absence of substrate washaway prevention members 2, but also by the frictional resistance of the substrate 3 itself against the surface of the construction area R. In this regard, this method reduces the contact area between the underline 4b of each wire 4A and the surface of the construction area R, while also allowing the substrate 3 to be held in the gaps below the underline 4b, thereby increasing the frictional resistance of the substrate 3 against the surface of the construction area R and, as a result, improving the effectiveness of preventing the substrate 3 from washing away.

In addition, with this construction method, the underline portion 4b of each wire 4, including the embracing wire 4A, is curved downwardly, making it less likely that the underline portion 4b will prevent the base material flow prevention member 2 placed above it from contacting the surface of the construction area R, thereby increasing the effectiveness of the base material flow prevention member 2 in preventing the flow of the base material 3.

In addition, in this example of vegetation restoration method, the upper line 4a of each wire 4, including the embracing wire 4A, is curved with an upward convex shape, so that the width of the upper line 4a narrows toward the top. If the upper line 4a is covered with the base material 3 so that at least the entire upper line 4a is not exposed, then as erosion or washing away of the base material 3 progresses due to, for example, a sudden downpour or typhoon, the amount of upper line 4a exposed to the surface of the base material 3 increases, strengthening its ability to capture airborne seeds and the like, preventing a significant loss of vegetation restoration capacity.

Furthermore, in this example of vegetation restoration construction method, the curvature of the upper line portion 4a and the lower line portion 4b of each wire 4 are made the same, and by standardizing their shapes, productivity is improved and the wire mesh 1 can be installed reversibly, eliminating the need for a front and back.

In addition, in this example of vegetation restoration, the substrate flow prevention member 2 has a roughly rectangular cross section, eliminating the need for a front and back (top and bottom) and allowing it to be reversibly inserted into the wire mesh 1. This also facilitates surface contact between the substrate flow prevention member 2 and the ground, improving its effectiveness in preventing the flow of the substrate 3. Furthermore, because the upper and lower wires 4a and 4b of each wire 4, including the embracing wire 4A, are curved, the substrate flow prevention member 2 effectively fills the space enclosed by the upper and lower wires 4a and 4b, and the upper and lower wires 4a and 4b contact or sink into the corners of the substrate flow prevention member 2, making it less likely for the substrate flow prevention member 2 to shift position or come off the wire mesh 1. This also makes it possible to secure the substrate flow prevention member 2 to the wire mesh 1 without the use of special fastening devices.

In addition, in this example of vegetation restoration method, by using natural fibers such as palm for the substrate washaway prevention member 2, its water retention capacity can be improved and it is expected that it will also have a fertilizer effect due to biodegradation.

Below, we will explain the details and results of the erosion resistance confirmation test conducted to compare the vegetation restoration method of this example with conventional vegetation restoration methods.

First, as an example of the present invention (this example), a vegetation restoration device D was prepared, in which substrate washaway prevention members 2 were attached at regular intervals to a wire mesh 1. As a conventional example, a generally flat diamond-shaped wire mesh (lath wire mesh) was prepared.

Two test specimen frames were constructed from flat, roughly rectangular boxes with the tops removed. Each was filled with compacted decomposed granite soil to a height of 5 cm. Vegetation restoration device D, an embodiment of the present invention, was fixed to one test specimen frame, while a conventional wire mesh was fixed to the other. A growth substrate material (substrate 3) was sprayed onto each frame to a thickness of 3 cm. Each test specimen frame was then placed in a rainfall test device with a 1:1.0 (45°) gradient. Piano wire was stretched across the surface of each test specimen frame, dividing the surface into 16 4x4 grids. The average thickness of substrate 3 at nine intersections was measured and calculated every hour for six hours at an hourly rainfall of 100 mm/hour. The results are shown in Table 1 and Figure 3.

As is clear from the results shown in Table 1 and Figure 3, the thickness of the substrate 3 is greater and the erosion prevention effect is greater when the product of the present invention is used than when the conventional product is used.

The present invention is not limited to the above-described embodiment, and can of course be implemented in various modifications without departing from the spirit of the present invention. For example, the following modifications can be mentioned:

Topsoil (topsoil seed bank, topsoil mixed with buried seeds) collected from the construction area R or its surrounding area may be used as the base material 3. In this case, the vegetation restoration method of this example can be implemented as a forest topsoil utilization project to restore vegetation in harmony with the surrounding environment.

In the above embodiment, the wire mesh 1 is completely covered by the base material 3, but this is not a limitation; at least a portion of the wire mesh 1 may be left uncovered by the base material 3. In this case, the exposed portion of the wire mesh 1 on the surface of the base material 3 makes it easier to capture airborne seeds, fallen leaves, etc., making the vegetation restoration method of this example feasible as a natural invasion promotion method that excels in restoring vegetation in harmony with the surrounding environment. Furthermore, in this case, the amount of base material 3 used can be reduced, which also contributes to reducing the labor and costs required for construction.

Here, if the wire mesh 1 is covered with the base material 3 so that only the upper part (upper line portion 4a) of the wire mesh 1 is exposed, this exposed portion (upper line portion 4a) will extend in a direction oblique to the contour lines in the construction area R, which is a slope, and multiple exposed portions (upper line portions 4a) will be arranged in a roughly staggered pattern.

The material for the substrate flow prevention member 2 may be a shape-retaining material made by solidifying fibers with latex, resin, etc., or a thick, stiff nonwoven fabric. In any case, it is desirable for the substrate flow prevention member 2 to have sufficient strength in the thickness direction to prevent it from being crushed by the weight of the substrate 3 sprayed on top of it.

In the above embodiment, the embracing wire 4A and the other wires 4 have the same shape, but they may also have different shapes.

It goes without saying that the above modifications may be combined as appropriate.

REFERENCE SIGNS LIST 1 Wire mesh 2 Substrate flow prevention member 3 Substrate 4 Wire 4A Embracing wire 4a Upper wire portion 4b Lower wire portion 5 Anchor pin D Vegetation restoration device L Length R Construction area T Wire mesh thickness W Wire mesh width

Claims (4)

A vegetation restoration method in which a vegetation restoration device including a wire mesh and a long substrate washaway prevention member is placed on a slope together with a substrate including at least one of seeds, vegetation base material, fertilizer, and erosion prevention material,
The wire mesh has a three-dimensional thickness and is formed by engaging a plurality of wire rods bent in a generally spiral shape with each other so that the spiral axes of the wire rods are generally parallel to each other, and each wire rod is configured so that an upper line portion curved in a convex shape upward and a lower line portion curved in a convex shape downward are alternately connected to form a generally spiral shape,
The wire in which the base material flow prevention member is housed is configured to be an embracing member that helically embraces the base material flow prevention member, and this embracing is such that the base material flow prevention member contacts each of the upper line portion and the lower line portion that are repeatedly connected to the wire,
the embracing wire has an upper line portion that is curved convexly upward and a lower line portion that is curved convexly downward, the base material flow prevention member has a belt shape with a substantially rectangular cross section, and the upper line portion and the lower line portion are in contact with or sink into corners of the base material flow prevention member,
The vegetation restoration device, with the substrate washaway prevention members held on the deployed wire mesh, is fixed to the slope with anchor pins, and at this time, the substrate washaway prevention members are arranged along the contour lines of the slope, and a layer of substrate is formed to cover the vegetation restoration device;
A vegetation restoration method in which the base material washaway prevention member is made of natural fibers such as palm . The vegetation restoration method described in claim 1, wherein the curvature of the upper line portion and the lower line portion is the same. The vegetation restoration method described in claim 2, wherein the embracing wire is configured to form a flattened ellipse whose height is smaller than its width when viewed from one end of its spiral axis. 4. The vegetation restoration method according to claim 1, wherein the thickness of the substrate flow prevention member is smaller than its width.