JP7498486B2 - How to install vegetation mats - Google Patents

Description

The present invention relates to a method for constructing vegetation mats that are used, for example, for greening slopes (roads, mountainside slopes, riverbeds, riverbanks, lakeshores, etc.) and flat land (parks, etc.).

Patent Document 1 discloses a technology for a vegetation mat in which a grass mat is integrated with a flexible net material, in which the net portion of at least one side of the net material extends beyond the edge of the grass mat, and when the vegetation mats are lined up and installed on a slope or the like, the net materials are connected together as necessary with a connecting means such as staples, and this overlapping portion is secured to the slope or the like with an anchor pin (anchor), thereby effectively preventing the sides of the vegetation mat from rolling up.

JP 2001-008547 A

However, in the conventional vegetation mat construction method, there is a concern that the anchor pins may get caught in the net material due to rust or burrs on the anchor pins, damaging the net material and the vegetation mat. There is also a problem that the labor and effort required for driving in the anchor pins is relatively large. Furthermore, when the slope is a riverbed or riverbank (see FIG. 10(A)), as shown in FIG. 10(B), the slope may temporarily swell when the river floods due to heavy rain, etc., and of the vegetation mat D and anchor pins 11 that are lifted up due to the swelling of the swollen slope, the vegetation mat D returns to its original state when the swelling of the slope is eliminated, while the anchor pins 11 do not return to their original state even when the swelling of the slope is eliminated because the frictional force of their periphery is reduced by the swelling of the entire slope, and are left protruding from the slope and vegetation mat D (see FIG. 10(C)), and may be washed away during subsequent floods or strong winds.

The present invention was made with the above in mind, and its purpose is to provide a method for constructing a vegetation mat that can prevent damage to net materials and improve workability when driving anchor pins, and prevent anchor pins from being washed away due to swelling of the slope.

In order to achieve the above-mentioned object, the method of constructing a vegetation mat according to the present invention involves laying a plurality of vegetation mats each having a flexible net material side by side, overlapping the net materials of adjacent vegetation mats, and driving a resin anchor member into the overlapping portion, and the anchor member is provided with a movement restriction portion that restricts movement of the anchor member in the pull-out direction relative to the net material by engaging with the net material after the anchor member penetrates the mesh of the net material, and the movement restriction portion is formed by a constriction in which the thickness of the anchor member gradually decreases from the head side to the tip side of the anchor member, and a step is created at the boundary between the constriction and the portion connected to the tip side of the anchor member relative to the constriction , and the anchor member has a straight portion that extends straight from the head side to the tip side without tapering, and a plurality of the movement restriction portions are provided on this straight portion (claim 1).

Here, the movement restriction portion may allow movement of the anchor member relative to the net material in the casting direction and restrict movement of the anchor member relative to the net material in the pull-out direction (Claim 3).

In the above-mentioned method for constructing a vegetation mat, the movement restriction portion may be provided in multiple locations within 5 cm of the neck of the head of the anchor member (Claim 2).

In the above-mentioned method for constructing a vegetation mat, a means for preventing the anchor member from coming off may be provided in an area of the anchor member that is closer to the tip than the movement restricting portion (claim 4).

In the above-mentioned method for constructing a vegetation mat, the retaining means may be provided in a spiral shape in the longitudinal direction of the anchor member (Claim 5).

In the above-mentioned method for constructing a vegetation mat, the longitudinal length of the vegetation mat may be 3 m or more, and multiple vegetation mats may be arranged only in the short direction of the vegetation mat (claim 6).

The present invention provides a method for constructing a vegetation mat that can prevent damage to net materials and improve workability when driving anchor members, and can prevent anchor members from being washed away due to swelling of the slope.

In other words, in the method of installing a vegetation mat according to the invention of each claim of this application, by making the anchor members out of resin, it is possible to prevent rust and burrs from occurring, and since the anchor members do not get caught on the net material when cast in place and penetrate smoothly through the mesh, it is possible to dispel concerns about damage to the net material and, ultimately, the vegetation mat.

Furthermore, if the anchor member is made of metal, its tip may collide with stones in the soil on the slope, making it impossible to drive it any deeper. Each time this happens, it can be time-consuming to remove the anchor member that has been partially driven in, drill a hole, and then drive the anchor member back in. However, by making the anchor member out of resin, which is more flexible than metal anchor members, the anchor member can be driven in even if it bends when its tip hits a stone, and it becomes easier to drive the anchor member so that its top surface is flush with the vegetation mat. In particular, in the case of river banks, the soil characteristics mean that stones of all sizes are often buried there, so using resin anchor members is extremely effective.

When the site where the vegetation mat is installed is a riverbed or riverbank, as mentioned above, with conventional anchor pins, there can be a problem that the pins are left protruding from the slope and the vegetation mat after temporary swelling of the slope. In this regard, the vegetation mat installation method of the invention according to each claim uses an anchor member equipped with a movement restriction portion, so that when the swollen slope tries to return to its original state together with the vegetation mat, the mesh of the net material engages with the movement restriction portion of the anchor member, and it is unlikely that only the anchor member will be left behind.

In the vegetation mat installation method of the invention according to claim 2, when an anchor member is cast into the overlapping portion of adjacent vegetation mats, it is desirable for the head of the anchor member to ultimately press against the grass on the upper surface while restricting (locking) the two net materials with the movement restricting portion of the anchor member, and this state can be easily achieved.

In the construction method for the vegetation mat of the invention according to claim 4, by providing a means for preventing it from falling off, the frictional force on the circumferential surface of the anchor member is increased, and when the swollen slope tries to return to its original state together with the vegetation mat, the effect of preventing only the anchor member from being left behind can be enhanced.

In the construction method for a vegetation mat according to the invention of claim 5, the provision of a slip-out prevention means increases the peripheral frictional force of the anchor member, enhancing the effect of preventing the anchor member from being left behind when the swollen slope attempts to return to its original state together with the vegetation mat.

The method of installing a vegetation mat according to the invention of claim 6 eliminates the need to join the vegetation mat in the longitudinal direction, improving the effectiveness of preventing the vegetation mat from peeling off or being washed away.

FIG. 2 is an explanatory diagram showing a schematic configuration of a vegetation mat during construction according to an embodiment of the present invention; FIG. 2 is a perspective view showing a configuration of a vegetation mat used in the vegetation mat application method. FIG. 2 is a perspective view showing a schematic configuration of the vegetation mat and a method for manufacturing the same. 1A to 1D are explanatory diagrams showing a schematic configuration of a method for manufacturing the vegetation mat, and FIGS. 1E and 1F are explanatory diagrams showing a schematic configuration of a method for applying the vegetation mat. FIG. 2 is a vertical cross-sectional view showing a schematic configuration of the vegetation mat application method. FIG. 2 is a vertical cross-sectional view showing the configuration of a main part of a revetment structure constructed by the vegetation mat construction method. (A) and (B) are front and side views of a net pin used in the vegetation mat installation method, (C) and (D) are longitudinal cross-sectional and plan views of a prevention plate used in combination with the net pin, and (E) and (F) are explanatory diagrams showing how to use the fixing device used in the vegetation mat installation method. FIG. 4 is a vertical cross-sectional view showing a state in which the net pin is used. 13A to 13D are front views showing several examples of anchor pins used in the vegetation mat installation method. 13A to 13C are schematic diagrams illustrating the problem of an anchor member being left behind due to temporary swelling of a slope.

The following describes an embodiment of the present invention with reference to the drawings.

The vegetation mat construction method according to this embodiment is carried out as part of a revetment construction method in which multiple vegetation mats D shown in Figure 2 are laid out vertically and horizontally in the vegetated revetment area of a river to build a revetment structure, and the state of the revetment structure during construction is shown in Figure 1.

The vegetation mat D is, for example, rectangular in plan view, measuring 2000 mm x 3000 mm, or square in plan view, measuring 2000 mm x 2000 mm, and is made by integrating a grass mat 3 with a flexible net material 2 having a nonwoven fabric 1 on its underside (see Figure 2).

The nonwoven fabric 1 is a member that is approximately rectangular in plan view and is formed so that the chemical fiber basis weight is 40 to 80 g/ ^m2 , and is formed using polyester fiber, palm mat, etc., which are materials that are highly durable and corrosion-resistant.

The net material 2 has approximately the same shape as the nonwoven fabric 1 in plan view, and is formed so that the tensile strength per meter of width is approximately 0.5 to 5 tons, and the mesh size is approximately 5 to 9 x 5 to 9 mm. The net material 2 is formed into a lattice shape using durable fibers such as nylon, polyester, aramid, carbon, polyacetal, etc., but it may also be made by braiding filaments made of the above fibers into a mesh with the same mesh size as above. The net material 2 in this example is a geotextile net with a polyester base fabric and an acrylic thermosetting resin covering.

The grass mat 3 consists of multiple pieces of grass 3a and soil 3b held in place by the roots of the grass 3a.

The vegetation mat D is composed of a main body 4 on which the grass mat 3 is formed, and a peripheral portion 5 formed on the periphery of the main body 4 where the grass mat 3 is not formed. In other words, the main body 4 is a portion composed of the nonwoven fabric 1, the net material 2, and the grass mat 3, and the peripheral portion 5 is a portion composed of the nonwoven fabric 1 and the net material 2. Note that when the main body 4 and peripheral portion 5 of adjacent vegetation mats D are overlapped, the peripheral portion 5 may not have the nonwoven fabric 1, and may consist only of the net material 2.

The peripheral portion 5 is composed of a peripheral portion 5a, for example 150 mm wide, formed on one side of the width of the vegetation mat D, a peripheral portion 5b, for example 100 mm wide, formed on one side of the length of the vegetation mat D, and a peripheral portion 5c, for example 100 mm wide, formed on the other side of the length of the vegetation mat D.

The vegetation mat D is manufactured as follows. First, as shown in FIG. 4(A), a nonwoven fabric 1 is laid in a field 6, and then a flexible net material 2 is placed on top of the nonwoven fabric 1 (FIG. 4(B)). A grass mat 3 that has been grown separately in the field 6 is laid on top of the net material 2 (FIG. 4(C)). Then, when the roots of the grass 3a are entangled with the nonwoven fabric 1 and the net material 2 (FIG. 4(D)), the roots of the grass 3a that have grown below the nonwoven fabric 1 are cut, and the net material 2 together with the nonwoven fabric 1 is peeled off from the field 6, completing the manufacture of the vegetation mat D (see FIG. 3).

In the manufacturing method of the vegetation mat D described above, by placing square pieces K (see FIG. 3) or the like on the periphery of the net material 2 when the manufacturing of the vegetation mat D starts, and removing these square pieces K or the like when the manufacturing of the vegetation mat D is completed, it is possible to provide the vegetation mat D with a peripheral portion 5 where the grass mat 3 is not formed.

Also, the arrangement of the above-mentioned square timbers K and the like may be omitted, and the peripheral portion 5 may be formed by crumbling off the peripheral portion of the grass mat 3 after the vegetation mat D is manufactured.

It is advisable to form a section with a dense mesh of about 2 to 5 cm width at each end of the above-mentioned peripheral portions 5a to 5c in order to prevent misalignment when connecting the net.

According to the manufacturing method of the vegetation mat D configured as described above, since the nonwoven fabric 1 is formed on the underside of the vegetation mat D, the amount of roots of the grass 3a that penetrates below the vegetation mat D is less than when the nonwoven fabric 1 is not provided, and the task of peeling off the vegetation mat D from the field 6 can be performed with less force.

The nonwoven fabric 1 can be attached to the net material 2 of the vegetation mat D by entangling the roots of the grass 3a of the turf mat 3 with the nonwoven fabric 1 and the net material 2, but in addition to this, it may also be attached using, for example, string or adhesive.

The manufacturing method of the vegetation mat D is not limited to the above configuration, and may be, for example, the following configuration. That is, first, the nonwoven fabric 1 is laid in the field 6, then a flexible net material 2 is placed on top of the nonwoven fabric 1, runners of grass 3a are planted on top of the net material 2 and covered with soil, the roots of the grass 3a become entangled with the nonwoven fabric 1 and the net material 2, and at the stage where the runners have grown into a grass mat 3, the roots of the grass 3a that have grown under the nonwoven fabric 1 are cut, and the net material 2 together with the nonwoven fabric 1 can be peeled off from the field 6.

As another method for manufacturing the vegetation mat D, the vegetation mat D can be obtained by spreading the nonwoven fabric 1 appropriately, for example on a workbench, layering a flexible net material 2 on top of this, placing a grass mat 3 on top of this, and integrating the three together using staples or other connecting means such as sewing (both not shown).

According to this manufacturing method, although the roots of the grass 3a of the grass mat 3 are not entangled with the nonwoven fabric 1 and the net material 2, these three are integrated by a connecting means, so that when the vegetation revetment is carried out, anchor pins (an example of an anchor member) 11 are driven into the overlapping portion of the peripheral portion 5, and the grass mat 3 can be firmly attached to the slope via the nonwoven fabric 1 and the net material 2. Over time, the grass roots of the grass mat 3 will entangle the nonwoven fabric 1 and the net material 2 and take root on the slope. According to this manufacturing method, in addition to using grass mat 3 that has already been grown, there is no need to wait for the roots of the grass mat 3 to entangle with the nonwoven fabric 1 and the net material 2, so the manufacturing time for the vegetation mat D can be further shortened by that time.

As described above, anchor pins 11 are driven into the overlapping portions of the peripheral portions 5, and it is desirable to reinforce the peripheral portions 5, which are, so to speak, the joints between adjacent vegetation mats D. As an example of this reinforcement, it is possible to use a material in which the nonwoven fabric 1 of the nonwoven fabric 1 and net material 2 constituting the peripheral portions 5 has a chemical fiber weight (40 to 80 g/ ^m2 ) greater than that of the nonwoven fabric 1 constituting the main body portion 4, or to provide two or more layers of nonwoven fabric 1 at the peripheral portions 5.

Next, the construction method of the vegetation mat D will be explained using Figures 1, 4 (E), (F) and 5. In Figure 1, R is the direction of water flow. To construct the vegetation mat D on the river embankment (one example of a slope) N for vegetation bank protection, first, as shown in Figure 1, the flooded area at the foot of the embankment or the part A that will be flooded for a considerable period of time is appropriately excavated, and a construction method for laying a basket mat 7, for example, is carried out in this excavated part A (laying rubble or futon baskets is also suitable).

At this time, a net material 8 similar to the net material 2 described above is laid over an appropriate width under the basket mat 7, with its upper edge 8a protruding toward the slope N side (the vegetated bank protection area side) of the upper part of the basket mat 7. Meanwhile, as shown in Figure 5, a net material 9 similar to the net material 2 described above is buried in the vicinity of the expected maximum water level H during flooding, or preferably in the vegetated bank protection area slightly above the maximum water level H, with its protruding edge 9a (see Figure 1) protruding on the river side.

In addition, within the vegetated bank protection area, net material 10 similar to net material 2 described above is buried across the upper and lower net materials 9 and 8. Taking into account the flow speed during flooding, the net materials 10 are buried at intervals of, for example, 10 to 30 meters in the direction of the river flow, with a portion 10a exposed toward the downstream side.

If necessary, it is desirable to fix the net materials 9 and 10 to the river slope N with anchor pins 11 (see Figure 5).

Then, as shown in FIG. 1, the vegetation mat D with the peripheral portion 5a facing upstream is hooked with the hook member 12 to the upper peripheral portion 5c (when the water flow direction R is opposite to that shown in FIG. 1 or when the vegetation mat D is installed on the opposite bank of the slope N shown in FIG. 1, the peripheral portion 5b is used instead of the peripheral portion 5c, but the following description of the case where the peripheral portion 5b is used is omitted). Then, using a crane 13 or the like, multiple vegetation mats D having the above configuration are stretched on the slope N, for example, from the downstream side to the upstream side of the vegetation revetment area and from the bottom side to the top side of the vegetation revetment area (see FIG. 4(E)).

At this time, as shown in FIG. 5, for the vegetation mat D to be placed at the lower end of the vegetation revetment area, the upper edge 8a protruding from the net material 8 laid under the basket mat 7 is overlapped from above with the lower part (peripheral part 5b) of the peripheral part 5 of the lower end vegetation mat D1, and anchor pins 11 are driven into both.

In addition, for adjacent vegetation mats D in the vertical direction of the vegetation revetment area, the lower part (peripheral part 5b) of the peripheral part 5 of the upper vegetation mat D is overlapped from above onto the upper part (peripheral part 5c) of the peripheral part 5 of the lower vegetation mat D, and anchor pins 11 are driven into both of them.

Furthermore, for the vegetation mat D that is placed near the highest water level H of the vegetation bank area (connected to the protruding edge portion 9a of the net material 9), the upper part of its peripheral portion 5 (peripheral portion 5c) is overlapped from above with the protruding edge portion 9a of the net material 9, and anchor pins 11 are driven into both. However, at this time, due to the length dimension of the vegetation mat D, the upper end of the vegetation mat D may exceed the protruding edge portion 9a. In this case, the anchor pin 11 can be driven into the overlapping portion of the protruding edge portion 9a, or the length dimension of the vegetation mat D can be adjusted by cutting the net material 2, etc., and the two 5c and 9a can be overlapped.

On the other hand, when laying multiple vegetation mats D from the downstream side to the upstream side of the vegetation revetment area, the downstream part of the upstream vegetation mat D is overlapped from above onto the upstream peripheral part 5a of the downstream vegetation mat D, and anchor pins 11 are driven into the overlapping part. Also, the upstream peripheral part 5a of the downstream vegetation mat D is overlapped onto the net material 10, and these two 10, 5a are connected by a connecting means such as coil wire or staples (not shown), and the downstream part of the upstream vegetation mat D is overlapped onto this overlapping part, and anchor pins 11 are driven into the overlapping part of these three.

At this time, due to the width dimension of the vegetation mat D, the vegetation mat D may exceed the net material 10. In this case, the connection by the connecting means can be stopped and an anchor pin 11 can be driven into the overlapping portion with the net material 10, or the vegetation mat D can be cut and its width dimension adjusted so that the vegetation mat D does not exceed the net material 10.

The overlapping portions of adjacent vegetation mats D in the vertical and horizontal directions and the overlapping portions of the vegetation mats D and the net material 9 may be secured to connecting members 14 that have been buried in the vegetation revetment area in advance. If necessary, soil 15 (see Figure 1) may be applied to the turf mat 3 so as to cover all or any of the vegetation mats D.

In the above embodiment, as shown in Figures 1 and 5, a grass mat S in which the nonwoven fabric 1 and the net material 2 are not integrated is stretched in the vegetation revetment area above the buried area of the net material 9. However, it goes without saying that the grass mat S may be replaced by a vegetation mat D of the above configuration.

According to the above-mentioned construction method of the vegetation mat D, the vegetation mat D used in the construction method is a highly shape-retaining vegetation mat D in which the strong surface roots of the grass mat 3 are firmly rooted in the nonwoven fabric 1 and the net material 2, and adjacent vegetation mats D are overlapped and fixed to the slope N with anchors 11 or the like, so that the grass mat 3, whose four sides are essentially connected to each other, can be firmly attached to the slope N via the nonwoven fabric 1 and the net material 2, and over time the grass mat 3 will become firmly rooted in the slope N (see Figure 4 (F)).

As a result, uniform greening of the entire slope N can be expected, and even if the river floods immediately after the construction of the vegetation mat D, the vegetation mat D will not easily crumble or peel off due to the flowing water, and will function as a highly hydrophilic bank immediately after construction, which not only looks great, but also effectively prevents erosion of the slope N due to flowing water.

In particular, the net material 2 on the upper and upstream sides of adjacent vegetation mats D is overlapped from above with the net material 2 on the lower and downstream sides of vegetation mats D, so that when the water level rises, the edges of the net material 2 do not resist the flow of water, allowing the water to flow smoothly, and the flow of the vegetation mats D is more effectively prevented.

In addition, nonwoven fabric 1 is formed on the underside of vegetation mat D, and this nonwoven fabric 1, like grass mat 3, has a suction prevention effect that prevents soil from being sucked out from the back side of vegetation mat D due to running water during flooding. Therefore, even if a part of grass mat 3 is missing from vegetation mat D due to, for example, insufficient growth of grass 3a at the beginning of construction, or the missing area of grass 3a expands due to the invasion of weeds after construction (including replacement of grass with clump-like plants) or the decline of grass 3a, the nonwoven fabric 1 prevents soil from being sucked out from that part and can complement the function of the missing grass 3a. Furthermore, nonwoven fabric 1 can also prevent soil and sand from being sucked out from the peripheral part 5 where grass mat 3 is not formed or from the underside of the joint part of vegetation mat D.

In order to achieve the above-mentioned suction prevention effect, it is desirable for the nonwoven fabric 1 to be difficult for the soil and sand that form the slope N to pass through, and to have multiple holes or gaps that allow the roots of the grass 3a of the turf mat 3 to pass through to a certain extent.

In addition, since the vegetation mat D has nonwoven fabric 1 at its joints, it is possible to eliminate the need to install suction prevention materials (such as suction prevention sheets) on-site to prevent soil, sand, etc. from being sucked out by running water, thereby reducing construction costs.

Furthermore, since the nonwoven fabric 1 does not allow soil or sand to pass through, it can suppress and hinder the growth of weeds that have been blown into the vegetation mat D from the surrounding area after construction, thereby preventing the invasion of weeds.

In the construction method of the vegetation mat D having the above-mentioned configuration, the vegetation mat D may be stretched on the slope N by using the crane 13 as described above, or may be stretched by hand, depending on the weight of the vegetation mat D. In the case of a site where a crane 13 can be used, the vegetation mat D can be made longer and the weight can be increased, so the vegetation mat D is manufactured so that its longitudinal length corresponds to the length of the vertical direction of the construction area (slope length in the case of a slope) (3 m or more, for example 15 m), rolled up and transported to the site, and the vegetation mat D is constructed so that its longitudinal direction is along the vertical direction of the construction area while being hung by the crane 13. In this way, it is only necessary to arrange multiple vegetation mats D in the short direction (horizontal direction) of the vegetation mat D, and there is no need to join the vegetation mats D in the longitudinal direction (vertical direction). In this case, it is still necessary to connect adjacent vegetation mats D horizontally (the short side direction of the vegetation mats D), but since there is no need to join the vegetation mats D vertically, this is highly effective in preventing the vegetation mats D from peeling off or being washed away.

According to the vegetation mat D configured as described above, and the manufacturing and construction methods thereof, by combining the nonwoven fabric 1 with the grass mat 3, it is possible to prevent soil and sand from being sucked out by the flowing water even if the speed of the flowing water contacting the vegetation mat D is 3 (m/s) or more. Also, because the rhizomes of the grass 3a of the grass mat 3 are entangled in the tough net material 2, the grass is not easily peeled off by the flowing water. Furthermore, it is possible to prevent erosion of the river slope and improve the scenery immediately after construction.

In addition, in the case of conventional vegetation mat construction using general suction prevention materials, if the general suction prevention material is placed directly underneath the vegetation mat, the roots and stems of grass and other plants cannot penetrate the slope, so after the general suction prevention material is placed on the bottom layer, it is covered with about 10 to 30 cm of soil and then the grass or other plants are laid on top of that (meaning that construction over at least two steps is required), but with the vegetation mat D configured as described above and its construction method, construction can be completed in just one step.

In this embodiment, as shown in FIG. 6, a revetment structure is constructed by installing a retaining material 16 that covers at least the upstream portion of the vegetation mat (upstream vegetation mat) D laid at the upstream end of the slope N or at least the downstream portion of the vegetation mat (downstream vegetation mat) D laid at the downstream end of the slope N using the construction method for the vegetation mat D having the above-mentioned configuration.

Here, the retaining material 16 is a net that is installed to hold down at least the upstream portion of the upstream vegetation mat D or at least the downstream portion of the downstream vegetation mat D, and can be the same as the net material 2 described above.

A part of the retaining material 16 (a part that does not cover the vegetation mat D) is a buried part 16a that is buried in the ground, and this buried part 16a is fixed in the ground by an anchor member 17 that is buried in the ground. Specifically, before laying the upstream vegetation mat D or the downstream vegetation mat D, the soil is dug and a hole is made for burying the buried part 16a, and the anchor member 17 is driven into the buried part 16a that is laid on the bottom of the hole, for example, and fixed therein. After that, the part of the retaining material 16 that is not to be buried is pulled out above ground, and the hole is backfilled, and after rolling as necessary, a vegetation mat (upstream vegetation mat or downstream vegetation mat) D is placed on top of the backfilled part, and the retaining material 16 is layered on top of it, and anchor pins 11 that penetrate the retaining material 16 and the vegetation mat D are driven into appropriate places so that the retaining material 16 holds down the vegetation mat D.

In this way, the retaining material 16 is partially buried in the ground and further secured in place by the anchor member 17, making it less likely to be washed away by running water.

Furthermore, as shown in FIG. 6, if the buried structures 18 are connected to the upstream side of the upstream vegetation mat D covered by the retaining material 16 or the downstream side of the downstream vegetation mat D, the soil on the upstream side of the upstream vegetation mat D or the downstream side of the downstream vegetation mat D is eroded by the erosion of flowing water, and this erosion extends to the soil below the upstream vegetation mat D or the downstream vegetation mat D, and the upstream vegetation mat D or the downstream vegetation mat D is peeled off from the slope N and washed away. This configuration in which the buried structures 18 are connected is particularly effective when, as described above, backfilling is performed when burying part of the retaining material 16 in the ground and a vegetation mat (upstream vegetation mat or downstream vegetation mat) D is placed in this backfilled area. This is because the backfilled area of soil has a lower pressure than the surrounding area even if it is compacted, and is easily eroded by flowing water.

Therefore, the buried structure 18 is preferably one that is highly durable and impermeable, and may be constructed, for example, by pouring mortar or concrete on-site, or by burying masses of prefabricated concrete blocks or concrete slabs. In addition, the buried structure 18 may be constructed by burying sandbags, basket mats, rubble, futon baskets, etc., although they will have water permeability.

In the revetment structure constructed as described above, by covering at least the upstream portion of the upstream vegetation mat D or at least the downstream portion of the downstream vegetation mat D with the retaining material 16, peeling or washing away of the upstream vegetation mat D or the downstream vegetation mat D due to flowing water can be prevented. If peeling or washing away of the upstream vegetation mat D or the downstream vegetation mat D occurs, there is a risk that peeling or washing away of the vegetation mat D connected to these will occur in a chain reaction starting from that part. However, in the revetment structure of this embodiment, peeling or washing away of the upstream vegetation mat D or the downstream vegetation mat D, which is the starting point of such chain reaction of peeling of the vegetation mat, can be prevented in advance, and the vegetation revetment of the vegetation revetment area can be secured.

The net-like retaining material 16 is water-permeable, and the supply of moisture from rainfall, etc. to the grass 3a of the vegetation mat D held down by this retaining material 16 is not impeded, so good growth of the grass 3a can be expected.

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

In the above embodiment, the vegetation mat D is constructed using a vegetation mat D in which the nonwoven fabric 1 is already integrated, but this is not limiting. The nonwoven fabric 1 may first be stretched over the slope N, and then the pre-integrated flexible net material 2 and grass mat 3 may be stretched over the nonwoven fabric 1 using a connecting means such as staples or sewing.

In this case, to stretch the nonwoven fabric 1 over the slope N, the periphery or other appropriate parts of the nonwoven fabric 1 can be anchored to the net material 8, 9, 10, etc., and this anchoring can also be used to stretch the net material 2 and the grass mat 3.

The nonwoven fabric 1 may be stretched over the entire slope N, but if it is stretched only over the areas that correspond to the joints of the vegetation mat D to be installed, the amount of nonwoven fabric 1 required can be reduced, making it possible to cut costs.

As a connecting structure for the overlapping portions of the peripheral portions 5a, 5b, and 5c of the net material 2, the peripheral portions 5a to 5c may be folded downward and engaged with the connecting fittings 14, and anchors 11 may be installed as necessary.

The vegetation mat D of the above embodiment has peripheral portions 5a to 5c that protrude from three sides. Therefore, even if the water flow direction R is opposite to that shown in FIG. 1 or if the vegetation mat D is constructed on the opposite bank of the slope N shown in FIG. 1, the vegetation mat D can be laid by turning the vegetation mat D in the opposite direction to that shown in FIG. 1. Moreover, compared with a vegetation mat D having peripheral portions that protrude from all four sides, the structure can be simplified and made more compact. However, this is not limited to this, and the vegetation mat D may have peripheral portions 5a and 5b (or 5a and 5c) that protrude from only two adjacent sides. In this case, for example, to construct a vegetation mat D on each side of a river, two types of vegetation mats D (a vegetation mat D having peripheral portions 5a and 5b, and a vegetation mat D having peripheral portions 5a and 5c) may be used.

Alternatively, the anchor pins 11 may be driven into the vegetation mat D itself without providing the peripheral portions 5a to 5c.

The buried structure 18 does not have to be a new structure installed when constructing the revetment structure, but may be an existing structure. In this case, the upstream vegetation mat D or the downstream vegetation mat D and the retaining material 16 may be provided so as to be connected to the existing buried structure 18.

When a new buried structure 18 is to be installed, the retaining material 16 may be connected to the buried structure 18 by means of embedding the retaining material 16 in the buried structure 18, placing it under the buried structure 18, engaging it with the buried structure 18, or tying it to the buried structure 18. In this case, the retaining material 16 becomes less likely to peel off, and the stability of the retaining material 16 covering the vegetation mat D, and therefore the stability of the vegetation mat, can be improved.

In the retaining material 16, a suction prevention material such as nonwoven fabric may be provided on the underside of at least the portion that covers the vegetation mat D.

In addition, a portion of the retaining material 16 may not be buried, but may be connected to, for example, a heavy object (not shown). In this case, the heavy object may be a sandbag, a basket mat, rubble, a futon basket, etc., and the connection method may be to place the heavy object on the retaining material 16, or to directly or indirectly engage or fasten the retaining material 16 to the heavy object.

The retaining material 16 and the embedded structure 18 may be provided on either the upstream portion (upstream side) of the upstream vegetation mat D or the downstream portion (downstream side) of the downstream vegetation mat D, but it is preferable to provide them on both.

Alternatively, instead of using the retaining material 16, the upstream part of the upstream vegetation mat D or the downstream part of the downstream vegetation mat D may be buried in the ground, and the weight may be placed on top of the buried part. In this case, the soil or weight placed on top of the upstream part of the upstream vegetation mat D or the downstream part of the downstream vegetation mat D will function as a retaining material.

In the above embodiment, anchor pins 11 and connecting members 14 are used to secure vegetation mat D, but instead of one or both of these, net pins 19 (one example of an anchor member) shown in Figures 7 (A) and (B) may be used. The net pins 19 have a roughly rectangular plate-shaped base 19a and at least two (four in total in the illustrated example) insertion portions 19b arranged in a row in the longitudinal direction of the base 19a, and each insertion portion 19b has a pointed tip to have a cross-shaped rod shape in cross section, and a return structure 19c near its base.

The net pin 19 can be inserted into the ground so that it passes through the mesh of the net material 2, etc., to firmly secure the net material 2, etc. to the ground. As shown in Figure 8, by using the net pin 19 so that the longitudinal direction of the base 19a is in the vertical direction of the slope N, the vegetation mat D can be most effectively prevented from shifting out of position.

Instead of the anchor pin 11 (see FIG. 9(A)) used to secure the vegetation mat D in the above embodiment, an anchor pin 20 shown in FIG. 9(B) may be used. The anchor pin 20 is provided with a movement restricting portion (notch) 21 that restricts movement of the anchor pin 20 in the pull-out direction relative to the net material 2 after the anchor pin 20 penetrates the mesh of the net material 2. The movement restricting portion 21 is constituted by a constriction in which the thickness of the anchor pin 11 gradually decreases from the head side to the tip side of the anchor pin 20, and a step is created at the boundary between the constriction and the portion that continues from the constriction to the tip side of the anchor pin.

That is, the diameter (thickness) of the anchor pin 20 is larger than the mesh size of the net material 2, and the mesh of the net material 2 that the anchor pin 20 penetrates during casting is pushed open by the anchor pin 20, but is not damaged due to the flexibility of the net material 2. When the anchor pin 20 penetrates the mesh of the net material 2 by casting, its penetration is not restricted by the movement restricting portion 21, but the movement of the anchor pin 20 in the pull-out direction relative to the net material 2 is restricted by the movement restricting portion 21 with which the net material 2 engages. The anchor pins 11 and 20 may have a circular cross-sectional shape, a regular polygon such as a square, or another polygonal shape, or may have a shape other than these.

As mentioned above, when the site where the vegetation mat D is installed is a riverbed or riverbank, a problem can occur with conventional anchor pins, in that they are left behind protruding from the slope and the vegetation mat D after temporary swelling of the slope occurs. In this regard, with the anchor pin 20 provided with the movement restriction portion 21, when the swollen slope attempts to return to its original state together with the vegetation mat D, the mesh of the net material 2 engages with the movement restriction portion 21 of the anchor pin 20, making it difficult for the anchor pin 20 to be left behind alone.

Here, as shown in FIG. 9(B), it is preferable to provide multiple movement restriction parts 21 (three in the illustrated example) within 5 cm from the neck of the head of the anchor pin 20. That is, in the construction method of the vegetation mat of this embodiment, the anchor pin 20 is driven into the overlapping part of adjacent vegetation mats D, and the anchor pin 20 penetrates the slope soil while penetrating the overlapping part where at least the soil, grass mat 3, net material 2, and grass runner on one vegetation mat D side and the soil, net material 2, and grass runner on the other vegetation mat D side are stacked. At this time, it is essential that the two net materials 2 are restricted (locked) by the movement restriction parts 21 of the anchor pin 20, and at that time, it is desirable that the head of the anchor pin 20 finally presses the grass on the upper surface side. At this time, in order to lock the two net materials 2 to the movement restriction parts 21 of the anchor pin 20, it is preferable to provide the movement restriction parts 21 as described above.

At this time, it is desirable to lock the two net materials 2 at one point in the axial direction (longitudinal direction) of the anchor pin 20 from the viewpoint of the tensile force in the surface direction (the anchor pin 20 is less likely to shake laterally), but the nonwoven fabric 1 (suction prevention material) and grass runner are sandwiched between the two net materials 2. The nonwoven fabric 1 is thin and easily compressed when the anchor pin 20 is cast, reducing its bulk, but the bulk of the grass runner varies depending on the growth condition of the grass, and it also holds the soil when it is growing in the field, so it has a certain amount of bulk. For this reason, it may not be possible to lock the two net materials 2 with one movement restriction part 21, so it is desirable to provide the movement restriction part 21 at two or more points in the axial direction of the anchor pin 20 in case of such an event.

The movement restriction portion 21 also functions as a so-called "return," and the more movement restriction portions 21 that are provided, the greater the pull-out resistance of the anchor pin 20.

The movement restricting portion 21 may be formed continuously over the entire area of the head of the anchor pin 20 from the neck to the tip taper, but from the viewpoint of the relative relationship with the net material 2, it is sufficient if it is within about 5 cm of the neck. From the viewpoint of pull-out resistance, it is preferable that it is formed continuously over the entire area. However, the more the portion (movement restricting portion) with a small shaft diameter of the anchor pin 20 increases, the lower the strength of the shaft becomes, and the anchor pin 20 may break during casting. However, if the material is resin (especially a soft resin with viscosity such as PP), it is unlikely to break until it is bent, and even if the tip of the anchor pin 20 hits a stone in the ground, the anchor pin 20 can bend flexibly and be cast to the end while avoiding the stone. However, if the material is made of a hard resin such as ABS, it is possible that it will break during casting.

As shown in FIG. 9(B), the anchor pin 20 may have a small diameter section 22 in the region closer to the head side than the movement restricting section 21, the diameter of which is constant throughout, and which is smaller than the diameter of the head side and tip side portions.

As described above, the movement restriction portion 21 is provided so that the anchor pin 20 is not left behind when the swollen slope returns to its original state together with the vegetation mat D, but as shown in Fig. 9 (C), if a slip-out prevention means (returned portion) 23 is provided in the area of the anchor pin 20 that is further towards the tip side than the movement restriction portion 21, the peripheral frictional force of the anchor pin 20 increases, further enhancing the effect. The slip-out prevention means 23 is a rod- or plate-shaped elastic part or member whose one end (root) is integrated or fixed to the shaft of the anchor pin 20 and whose other end extends from the one end towards the head side of the anchor pin 20 and away from the shaft of the anchor pin 20. The retaining means 23 bends so that the other end becomes a free end, and multiple retaining means 23 are offset in both the axial and circumferential directions of the anchor pin 20, reducing the penetration resistance when driving the anchor pin 20. Furthermore, because the retaining means 23 elastically deforms, it is less likely that the anchor pin 20 will come out when the retaining means 23 is subjected to water or wind pressure.

The retaining means 23 does not need to be strong enough to produce a general retaining effect, but only needs to be strong enough to return to its original shape while being embraced by the swelling ground and soil so that the anchor pin 20 is not left behind when the slope returns to its original shape after temporary swelling. Even if the retaining means 23 is soft as a whole, the base portion is strong against forces from above (forces in the direction in which the retaining means 23 spreads) and can sufficiently withstand the forces acting on the base portion as it returns to its original shape together with the ground and soil while being embraced by the swelling ground and soil.

Instead of or in addition to the retaining means 23 shown in FIG. 9(C), a retaining means 24 (see FIG. 9(D)) extending in a generally spiral shape along the outer surface of the anchor pin 20 may be provided. This retaining means 24 also increases the peripheral frictional force of the anchor pin 20, enhancing the effect of preventing the anchor pin 20 from being left behind as described above.

Incidentally, the movement restriction portion 21 (or a portion equivalent thereto) provided on the anchor pin 20 is also provided on the insertion portion 19b of the net pin 19 shown in Figures 7(A) and (B). However, the movement restriction portion 21 on the insertion portion 19b is configured by a constriction that connects a portion where the width of the net pin 19 gradually decreases from the head side to the tip side of the net pin 19, and a portion where the width is constant. In this way, the shape or configuration of the movement restriction portion 21 can be modified in various ways.

The net pin 19 shown in Figures 7(A) and (B) may be used in combination with the retaining plate 25 shown in Figures 7(C) and (D). The retaining plate 25 has a tapered hole 25a into which each insertion portion 19b can be inserted, and the inner surface of the tapered hole 25a is provided with a plurality of teeth 25b that engage with the movement restriction portion 21 of the insertion portion 19b. As a result, when the insertion portion 19b is inserted into the tapered hole 25a from its large-diameter opening side, the insertion portion 19b will not come out of the tapered hole 25a. For example, if the net pin 19 is placed on one (upper) surface of the net material 2 and the retaining plate 25 is placed on the other (lower) surface, and the insertion portion 19b is inserted into the mesh of the net material 2 and further into the tapered hole 25a, the net material 2 can be held in a tightly sandwiched state between the net pin 19 and the retaining plate 25. If this operation is performed while driving the insertion portion 19b into the slope, it is easy to firmly fix the overlapping portions of the peripheral portions 5 of adjacent vegetation mats D to the slope while holding them between the net pin 19 and the retaining plate 25.

7(E) and (F), one net pin 19 and two retaining plates 25 are integrated at a distance by a flexible, generally Z-shaped bending member 26. That is, the bending member 26 has a hinge portion 26c between a first portion 26a with which the net pin 19 is integrated and a second portion 26b with which the retaining plate 25 is integrated, and also has a hinge portion 26c between a third portion 26d with which another retaining plate 25 is integrated and the second portion 26b. For example, in the state of FIG. 7(E) (with each hinge portion 26c spread), by inserting one of the peripheral portions 5 of adjacent vegetation mats D between the first portion 26a and the second portion 26b and the other between the second portion 26b and the third portion 26d in the fastener as shown in FIG. 7(E) and folding each hinge portion 26c as shown in FIG. 7(F), the peripheral portions 5 of adjacent vegetation mats D can be held in a state in which they are strongly sandwiched between the net pin 19 and the two retaining plates 25. Of course, if this operation is performed while driving the inserting portion 19b into the slope, it is also easy to firmly fix the overlapping portions of the peripheral portions 5 of adjacent vegetation mats D to the slope while holding them between the net pin 19 and the two retaining plates 25.

The above-mentioned anchor pin 11, connecting member 14, net pin 19, and anchor pin 20 are preferably made of resin (recycled plastic or new plastic). The reasons for this are explained below. Note that, although the anchor pin 11 is used as an example below, the same applies to the other members.

If the anchor pin 11 were made of steel, for example, there would be a concern that rust or burrs on the anchor pin 11 would cause the driven anchor pin 11 to get caught on the net material 2, damaging the net material 2 and ultimately the vegetation mat D. This is especially true if the anchor pin 11 is a deformed L-shaped anchor made from a deformed rebar commonly used in civil engineering. However, by making the anchor pin 11 out of resin, rust and burrs can be prevented, and the anchor pin 11 will not get caught on the net material 2 when driven, and will smoothly penetrate the mesh, eliminating the above concerns.

In addition, if the anchor pin 11 is made of metal, the tip of the anchor pin 11 may collide with stones in the slope soil, making it impossible to drive it any deeper. Each time this happens, it can be time-consuming to remove the anchor pin 11 that has been driven partway, drill a hole, and then drive the anchor pin 11 again. However, by making the anchor pin 11 out of resin, which is more flexible than a metal anchor pin, the anchor pin 11 can be driven even if it bends when its tip hits a stone, and it becomes easier to drive the anchor pin 11 so that its top surface is flush with the vegetation mat D. In particular, in the case of river banks, due to the characteristics of the soil, large and small stones are often buried in the soil, so making the anchor pin 11 out of resin is extremely effective.

Furthermore, if the anchor pin 11 is made of iron, the head of the anchor pin 11 exposed on the surface of the vegetation mat D will rust over time, resulting in a poor appearance, but this is improved if it is made of resin.

When the resin used for the anchor pin 11 is ABS resin, the pin 11 tends to be hard and break easily, whereas when it is made of PP, it is soft and does not break easily, so it tends to be able to push through the gaps between the stones while bending. It is desirable for at least the tapered portion near the tip (sharp point) of the anchor pin 11 to be as soft as PP.

It goes without saying that the variations described in this specification may be combined as appropriate.

LIST OF SYMBOLS 1 Nonwoven fabric 2 Net material 3 Grass mat 3a Grass 3b Soil 4 Main body 5 Peripheral edge 5a-5c Peripheral edge 6 Field 7 Basket mat 8 Net material 8a Upper side 9 Net material 9a Protruding side 10 Net material 10a Part 11 Anchor pin 12 Hook member 13 Crane 14 Connecting member 15 Soil cover 16 Retaining material 17 Anchor member 18 Buried structure 19 Net pin 19a Base 19b Insertion portion 19c Return structure 20 Anchor pin 21 Movement restricting portion 22 Small diameter portion 23 Anti-slip means 24 Anti-slip means 25 Anti-slip plate 26 Bending member 26a First portion 26b Second portion 26c Hinge portion 26d Third portion D Vegetation mat S Grass mat

Claims (6)

When laying a plurality of vegetation mats each having a flexible net material side by side, the net materials of adjacent vegetation mats are overlapped with each other, and the overlapping portion is installed with a resin anchor member;
The anchor member is provided with a movement restricting portion that restricts movement of the anchor member in a pull-out direction relative to the net material by engaging with the net material after the anchor member penetrates the mesh of the net material ,
the movement restricting portion is configured by a constriction in which the thickness of the anchor member gradually decreases from the head side to the tip side of the anchor member, and a step is formed at a boundary between the constriction and a portion of the anchor member that is connected to the tip side of the constriction ,
A method for installing a vegetation mat, characterized in that the anchor member has a straight portion that extends straight from the head side to the tip side without tapering, and a plurality of the movement regulating portions are provided on this straight portion . The method for constructing a vegetation mat according to claim 1, wherein the movement restriction portion is provided in multiple locations within 5 cm of the neck of the head of the anchor member. The method for constructing a vegetation mat according to claim 1 or 2, wherein the movement restriction portion allows movement of the anchor member relative to the net material in the casting direction and restricts movement of the anchor member relative to the net material in the pull-out direction. The method for constructing a vegetation mat according to any one of claims 1 to 3, wherein a means for preventing the anchor member from coming off is provided in an area of the anchor member that is closer to the tip side than the movement restricting portion. The method for constructing a vegetation mat according to claim 4, wherein the retaining means is provided spirally in the longitudinal direction of the anchor member. The method for constructing a vegetation mat according to any one of claims 1 to 5, wherein the length of the vegetation mat in the longitudinal direction is 3 m or more, and a plurality of the vegetation mats are arranged only in the short side direction of the vegetation mat.