WO2024190490A1

WO2024190490A1 - Protective net and installation method of protective net

Info

Publication number: WO2024190490A1
Application number: PCT/JP2024/008033
Authority: WO
Inventors: 寛史橋口; 和人河野
Original assignee: 東京製綱株式会社
Priority date: 2023-03-13
Filing date: 2024-03-04
Publication date: 2024-09-19
Also published as: JP2024129303A; JP7305899B1

Abstract

Provided is a protective net that enables more efficient use of a buffering performance of a wire net itself and a blocking surface with a simple structure, thereby reducing the number of parts or simplifying installation work.　A protective net 1 includes: a plurality of support pillars 12; a wire net 11 that is suspended from an upper portion of the support pillars 12 toward a lower portion of an inclined surface, and in which ropes connected to anchors are not arranged on a blocking surface; and an upper wire net roll-out structure configured such that, when the wire net 11 is attached to the upper portion of the support pillars 12, the wire net 11 is rolled out from the upper portion of the support pillars 12 when impact energy such as a falling rock is applied to the wire net 11.

Description

Protection net and installation method of protection net

The present invention relates to a protective net installed on sloping ground and a method for installing the same.

One type of protective facility for keeping objects in a specified area on sloping ground, etc., is a protective net comprising a mesh body suspended downward from supports, and which is made up of a wire rope or other cable and a wire mesh.
Conventional techniques relating to such protective nets are disclosed in Patent Documents 1 to 4.

Japanese Patent Application Publication No. 11-148113 Patent No. 3825218 Patent No. 5007957 Patent No. 6343706

Patent documents 1 to 3 disclose protective nets in which a wire mesh is provided on a net body made of vertically and horizontally combined rope materials as a blocking surface. Both ends of each horizontal rope are fastened to anchors, and each vertical rope is connected to the horizontal ropes in a lattice shape with the upper parts of the vertical ropes on both sides fastened to the upper parts of the posts, and the wire mesh is provided on the net body formed of vertical and horizontal rope materials.
On the other hand, Patent Document 4 discloses a structure in which there are no vertical ropes, and a wire mesh is provided on a number of horizontal ropes whose both ends are fastened to anchors.
The protective nets in Patent Documents 1 to 3 require the work of constructing the net body by combining rope materials lengthwise and widthwise, and also the work of fastening these rope materials to the wire mesh, so construction is very time-consuming (costly).In addition, a large number of parts are required, such as parts for fastening each part, which also increases costs.
The protective net of Patent Document 4 does not have vertical ropes, and therefore the above problems can be reduced compared to Patent Documents 1 to 3. However, it requires wire mesh to be fastened to each horizontal rope across the entire blocking surface, and wire grips must be attached to each horizontal rope near both ends of the blocking surface, which still requires costs due to increased construction costs and the number of parts.
The basic idea of the protective nets disclosed in Patent Documents 1 to 4 is to catch falling rocks with rope materials (and shock absorbers attached to the rope materials) at the blocking surface. Since the wire mesh is fastened to the rope materials, the movement of the wire mesh is restricted at that point, and the shock absorbing performance of the wire mesh itself cannot be maximized.

In view of the above, the present invention aims to provide a protective net that makes more efficient use of the shock-absorbing properties of the wire mesh itself and allows for a simple structure for the blocking surface, thereby reducing the number of parts and simplifying the installation work.

(Configuration 1)
A protective net to be installed on a slope, comprising: a number of support posts; a wire mesh suspended from the tops of the support posts toward the bottom of the slope, with the wire mesh having ropes connected to fixing members not positioned on the blocking surface; and an upper wire mesh pay-out structure configured to pay out the wire mesh when impact energy from a falling rock or the like is applied to the wire mesh when the wire mesh is attached to the tops of the support posts.

(Configuration 2)
The protective net described in configuration 1, in which the upper wire mesh pay-out structure is composed of an upper wire mesh holding rope that is hung across the top of the support and slidably holds the top of the wire mesh, and a side connecting member that extends in the vertical direction on the side of the wire mesh and connects the side of the wire mesh to a side connecting rope whose one end is connected to an anchor, the side connecting member being connected to the top of the support and not connected to the wire mesh within a predetermined range downward from the top of the support.

(Configuration 3)
A protective net as described in configuration 2, wherein the side connecting member is connected to a plurality of the side connecting ropes, and the specified range is between the top of the support pillar and the uppermost side connecting rope among the plurality of the side connecting ropes.

(Configuration 4)
A protective net described in any of configurations 1 to 3, which is provided with a lower wire mesh pay-out structure that is configured to pay out the lower side of the wire mesh when impact energy from a falling rock or the like is applied to the wire mesh at the attachment of the lower side of the wire mesh.

(Configuration 5)
The protective net described in structure 4, in which the lower wire mesh pay-out structure is composed of a lower wire mesh holding rope body that slidably holds the lower part of the wire mesh, and a side connecting member that extends in the vertical direction at the side of the wire mesh and connects the side of the wire mesh to a side connecting rope body having one end connected to an anchor, the side connecting member being slidably connected to the lower wire mesh holding rope body and not connected to the wire mesh within a predetermined range upward from the connection position to the lower wire mesh holding rope body.

(Configuration 6)
A protective net as described in configuration 5, wherein the side connecting member is a rope body, an eye portion for connecting to the lower wire mesh holding rope body is formed at the lower end side of the rope body by a wire grip, and the specified range is the range from the connection position to the lower wire mesh holding rope body to where the wire grip is located.

(Configuration 7)
A protective net described in any of configurations 2 to 6, wherein the upper wire mesh holding rope has a first buffer device that extends in length while absorbing energy and maintains the connection by a stopper mechanism, and is connected to an anchor, and the side connecting rope has a second buffer device that does not have a stopper mechanism for maintaining the connection, while extending in length while absorbing energy.

(Configuration 8)
A protective net as described in configuration 5 or 6, in which the lower wire mesh holding rope body has a first buffer device that extends in length while absorbing energy and maintains the connection by a stopper mechanism, and is connected to an anchor, and the side connecting rope body has a second buffer device that does not have a stopper mechanism for maintaining the connection, while extending in length while absorbing energy.

(Configuration 9)
A protective net as described in configuration 7 or 8, wherein the second buffer device is formed by a band of multiple wires, and is provided with an eye portion formed by bending the central portion of the band, and two spiral portions extending from the eye portion, and the side connecting rope is wound around the two spiral portions with excess length, and when impact energy from a rockfall or the like is applied, the wound portions are configured to slide with frictional force.

(Configuration 10)
A protective net described in any one of configurations 2 to 9, comprising two cord arrangement paths at the upper part of the support pillar through which the upper wire mesh holding cord can be slidably passed.

(Configuration 11)
11. A protective net as described in any one of configurations 1 to 10, wherein the wire mesh has a double structure.

(Configuration 12)
A protective net as described in configuration 11, comprising an upper wire mesh holding cord hung across the top of the support, one of the two wire meshes that make up the double structure protruding upward above the other wire mesh, and the protruding portion of one of the wire meshes is folded back so as to wrap around the upper wire mesh holding cord, thereby allowing the upper part of the wire mesh to be slidably held by the upper wire mesh holding cord.

(Configuration 13)
A protective net as described in

configuration

11 or 12, comprising a lower wire mesh holding cord that slidably holds the lower part of the wire mesh, one of the two wire meshes that make up the double structure protruding downwardly beyond the other wire mesh, and the protruding portion of one of the wire meshes is folded back so as to wrap around the lower wire mesh holding cord, thereby causing the lower part of the wire mesh to be slidably held by the lower wire mesh holding cord.

(Configuration 14)
A method of constructing a protective net as described in

configuration

12 or 13, comprising the steps of: lifting one of two wire meshes that form the double structure to a predetermined height at the installation site of the protective net, and fastening the other wire mesh to it using a fastening coil; and further lifting the one wire mesh to which the other wire mesh is fastened, and attaching it to the upper wire mesh holding rope.

The present invention makes it possible to more efficiently utilize the shock-absorbing properties of the wire mesh itself and to give the blocking surface a simple structure, thereby providing a protective net with a reduced number of parts and simplified installation work.

FIG. 1 is a side view showing a protective net according to an embodiment of the present invention; FIG. 1 is a front view showing a protective net according to an embodiment; FIG. 1 shows a support pole of a protective net according to an embodiment. Diagram showing the top of the support FIG. 2 shows a second shock absorber (shock absorber grip) FIG. 1 shows a first shock absorber Photographs showing a method for constructing a protective net according to an embodiment Diagram and photograph showing the specimen used in the weight impact experiment A diagram showing the experimental setup for the impact test Photo showing the weight impact experiment

Below, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the following embodiment is one form for realizing the present invention, and does not limit the scope of the present invention.

1 and 2 are diagrams showing the configuration of a protective net according to an embodiment of the present invention, with FIG. 1 being a side view and FIG. 2 being a front view (viewed from the valley side).
The protective net 1 of this embodiment is a protective facility installed on sloping ground, and is a protective net that can respond to both falling rocks and avalanches, in which wire mesh is suspended from the top of posts toward the downslope.

As shown in FIGS. 1 and 2, the protective net 1 includes:
A plurality of columns 12;
A wire mesh 11 is suspended from the upper part of a support 12 toward a downward slope, and a rope such as a horizontal rope connected to a fixing member such as an anchor is not disposed on a blocking surface;
An upper horizontal rope (upper wire mesh holding rope body) 13 that is hung across the upper part of the support 12 and slidably holds the upper part of the wire mesh 11;
a lower horizontal rope (lower wire mesh holding rope body) 14 that slidably holds the lower part of the wire mesh 11;
A plurality of extension ropes (side connecting ropes) 16 each having one end connected to an anchor A3;
A vertical rope (side connecting member) 15 that extends in the vertical direction on the side of the wire netting 11 and connects the side of the wire netting 11 to a tension rope (side connecting rope) 16;
a first buffer device 18 provided on the upper horizontal rope (upper wire mesh holding rope body) 13 and the lower horizontal rope (lower wire mesh holding rope body) 14;
A second shock absorber 17 provided on the extension rope (side connecting rope) 16;
Each stay rope for supporting the support 12;
It is equipped with:

The wire mesh 11 constituting the blocking surface is a high-strength wire mesh formed using high-tensile wire rods having a tensile strength of 1400 MPa or more.
In the protective net 1 of this embodiment, the wire mesh 11 is composed of three rows of

wire mesh

11a, 11b, and 11c. Each of the

wire meshes

11a, 11b, and 11c is composed of two wire meshes overlapped on the blocking surface, and a single wire mesh is composed at the upper and lower ends. In other words, one of the overlapping wire meshes is formed longer in the vertical direction, and the other (shorter) wire mesh is overlapped so that the upper and lower parts of the one wire mesh protrude. This results in "one of the two wire meshes constituting the double structure protruding upward from the other wire mesh" and "one of the two wire meshes constituting the double structure protruding downward from the other wire mesh." In this case, it is desirable to place the other (shorter) wire mesh on the collision surface side (mountain side) (as will be explained below, since the wire mesh 11 is attached to the rope material at the upper and lower protruding parts of one (longer) wire mesh, it is preferable to reduce the risk of one (longer) wire mesh being broken as much as possible, and therefore it is better not to place one (longer) wire mesh on the collision surface side where it will come into direct contact with falling rocks), but the other (shorter) wire mesh may also be placed on the opposite side of the collision surface (valley side).In addition, it may be a wire mesh of the same length that is basically two pieces overlapping each other by overlapping them slightly above and below, so that there is only one wire mesh at the upper and lower ends of the wire mesh, etc.
The wire mesh 11 is a diamond-shaped wire mesh, and is arranged so that the row lines constituting the wire mesh are oriented horizontally, thereby enabling it to be unfolded and folded vertically (by folding along the horizontal creases).
Each of the wire meshes 11a, 11b, and 11c is overlapped at the joints, and fastened to each other by two rows of fastening coils C1 arranged vertically at each overlapping portion. The reason why the wire mesh 11 is composed of three rows of wire meshes 11a, 11b, and 11c is that the width of the wire mesh is insufficient for the span between the posts (based on the convenience of the wire mesh manufacturing equipment and the size considering the transportation and operation at the site (sloping ground)), and three rows are not essential. If one or two rows are sufficient, one or two rows may be used, or four or more rows may be used.
The protective net 1 has a very simple structure without rope material (ropes connected to anchors) on the blocking surface. This also means that the movement of the wire mesh is not restricted by the rope material on the blocking surface, so the blocking surface has a highly flexible structure.
The blocking surface refers to the portion of the face material (wire mesh) that is assumed to be hit by falling rocks according to the design concept. In the protective net 1 of this embodiment, this is the wire mesh portion having a double structure, and is the portion inside the vertical ropes 15 on both sides.

3 and 4 are diagrams showing the support 12, with Fig. 3(a) being a front view, Fig. 3(b) being a side view, Fig. 3(c) being a bottom view, Fig. 4(a) being a top view, Fig. 4(b) being a diagram showing the partition plate 121 at the top of the support, and Fig. 4(c) being a diagram showing the mountain-side side panel 122.
In this embodiment, the support pillar 12 is formed using an H-shaped steel, and has a base plate at its bottom having a hinge plate 124 at its bottom, and a rope holding structure at its top for slidably holding the upper horizontal rope 13 (the respective components are welded to the bottom and top of the H-shaped steel).
The support 12 has a hinge structure and is installed on a foundation formed on a slope so as to be able to tilt. A hinge plate (not shown) corresponding to the hinge plate 124 at the bottom of the support 12 is installed on the foundation, and the two are joined together using a bolt or the like as a hinge axis, so that the support 12 is installed so as to be able to tilt in the direction of the slope.
The installation posture of the support pillar 12 is maintained by connecting each of the stay ropes described below to the support pillar 12.
The rope retaining structure on the upper part of the pillar has a top plate 123 (see Figure 4 (b)) that makes the upper surface of the pillar curved when viewed from the front, two partition plates 121 welded onto the top plate 123, and a mountain-side side panel 122 provided on the mountain side of the upper part of the pillar.
The top plate 123 is a component that provides an R on the upper surface of the pillar to facilitate the movement of the upper horizontal rope 13 which slides laterally (left and right when viewed from the front) on the upper surface of the pillar (reducing damage to the upper horizontal rope 13 during sliding).
The partition plate 121 is a partition plate for forming the rope arrangement path P1 (and P2) through which the upper horizontal rope 13 slidably passes, and as shown in Fig. 4(b), the bottom side is shaped to conform to the top plate 123 and is fixed (welded) to the top plate 123. The partition plate 121 is formed so that both ends are bent toward the valley side when viewed from above (Fig. 4(a)). This shape is intended to facilitate the movement of the upper horizontal rope 13, which is pulled toward the valley side in the event of a rockfall collision, etc. (reducing damage to the upper horizontal rope 13 during sliding).
In this embodiment, two partition plates 121 are used to form two rope arrangement paths P1 and P2 (see FIG. 4(a)). The rope arrangement paths P1 and P2 make it possible to slidably hold the two upper horizontal ropes 13, respectively, and the upper horizontal ropes of adjacent spans can be supported by a single support. In other words, by sharing the support for adjacent protective nets, further cost reductions can be achieved. Note that if such a function is not required, there may be only one rope arrangement path (one partition plate 121).
The mountain side side plate 122 is a flat plate-like member provided on the mountain side to form the rope arrangement path P1. The corners on both sides of the mountain side side plate 122 on the valley side are chamfered to reduce damage to the upper horizontal rope 13 during sliding (see FIG. 4(c)).
The partition plate 121 and the mountain side panel 122 have

bolt fastening holes

121h and 122h formed at corresponding heights, respectively, and the upper horizontal rope 13 is arranged in the rope arrangement path P1 (and P2) and then fastened by passing a pin bolt or the like through the

bolt fastening holes

121h and 122h to prevent the upper horizontal rope 13 from coming off the support 12.
Mounting members 125 for fastening stay ropes are provided on the upper part of the support 12. The mounting member 125 on the mountain side is fixed (welded) to the mountain side side plate 122, and the mounting member 125 on the valley side is fixed (welded) to the valley side side plate 126 so as to be at the same height as the mounting member on the mountain side. In addition, the mounting members 125 on both lateral sides of the support 12 are directly fixed (welded) to the flanges of the H-shaped steel.
In this embodiment, the pillars 12 are formed using H-shaped steel, but the present invention is not limited to this, and any material that can be used as a pillar (having the necessary strength) may be used. Similarly, the configuration for attaching the stay ropes, etc. is not limited to the illustrated attachment member 125, and any structure or mechanism that is used for attaching a rope, etc. may be used.

In this embodiment, the stay rope for supporting the support 12 is as follows:
A stay rope SW1 that connects the upper part of each pillar 12 (the mounting member 125 on the mountain side of the pillar 12) to the anchor A1 that is driven into the mountain side;
A stay rope SW2 that connects the upper part of each support 12 (the mounting members 125 on both lateral sides of the support 12) to the anchors A5 that are driven into the slope on both sides of each support 12;
It is equipped with:
In addition to the tie rope, the structure for connecting each rope material to each component may be any structure (structure that provides the required strength) used for fastening each component such as a rope body, such as each component used to form an eye portion, such as a wrapping grip or wire grip, or a connecting member such as a shackle or ring member.
In addition, while the present embodiment uses as an example a structure equipped with the above-mentioned backing ropes, the present invention is not limited to this, and in order to obtain the required fixing strength, the number of backing ropes (and anchors, etc. required to secure them) may be increased or decreased, or the positions at which they are installed may be changed.

The upper horizontal rope 13 is made of a wire rope, has a first buffer device 18, and is connected at both ends to anchors A2 driven into the slope (see FIG. 2).
The upper horizontal rope 13 is arranged in the rope arrangement path P1 (or P2) at the upper part of each of the two supports 12 and is supported slidably at the upper part of the supports 12.

The lower horizontal rope 14 is also made of a wire rope, has a first buffer device 18, and is connected at both ends to anchors A4 that are driven into the slope.

The vertical rope 15 is made of a wire rope, the upper end of which is connected to the upper part of the support 12, and the lower end of which is slidably connected to the lower horizontal rope 14. More specifically, an eye is formed at the upper end by a wire grip, and the vertical rope 15 is connected to a mounting member 125 on the valley side of the support 12 by using a connecting metal fitting such as a pin bolt. An eye is formed at the lower end by a wire grip, and the vertical rope 15 is slidably connected to the lower horizontal rope 14 via a connecting metal fitting such as a shackle (note that the vertical rope 15 may be slidably connected by passing the lower horizontal rope through the eye without using a connecting metal fitting such as a shackle).
The vertical ropes 15 are provided on both sides of the wire mesh 11 and connected to the wire mesh 11 and a plurality of overhanging ropes 16, thereby having the function of connecting the support provided by the overhanging ropes 16 on the sides of the wire mesh 11 with a line rather than a point.

The extension rope 16 is made of a wire rope, has a second buffer device 17, and is connected at one end to the vertical rope 15 and at the other end to an anchor A3 driven into the slope.
The number of extension ropes 16 can be increased or decreased as appropriate depending on the required strength and durability.

5A and 5B are diagrams showing the second shock absorber 17, with FIG. 5A being a diagram showing the installed state, FIG. 5B being a diagram showing the state before use, and FIG. 5C being a diagram showing the state during installation.
The second shock absorber (shock absorber grip) 17 is formed by a strip of multiple wires bundled together, and is provided with an eye portion 171 formed by bending the central portion of the strip, and two spiral portions 172 extending from the eye portion 171.
The second buffer device 17 is wound around the extension rope (side connecting rope) 16 by two spiral portions 172 with an excess portion 161 (see Figure 5 (c)). When impact energy (energy above a specified level) from a rockfall or the like is applied, the wound portion, that is, the spiral portion 172, is configured to slide against the extension rope 16 with frictional force.
In this embodiment, the second shock absorber 17 (and the extension rope 16 connected thereto) is connected to the vertical rope 15 using a wire grip WG (see FIG. 5(a)).
The second shock absorber 17 is structurally similar to a wrap grip, but is conceptually completely different from a wrap grip in that it is designed to be slippery. The second shock absorber 17 can also be formed by shortening the spiral portion of a typical wrap grip.
When impact energy from a rockfall or the like is applied, the second shock absorber 17 functions to maintain the shape of the net without sliding until a certain tension is applied, and when a certain tension or more is applied, it functions to send out the extension rope 16 by friction. When the length of the sent-out length becomes longer than the excess length 161, the extension rope 16 comes out (the connection is not maintained), allowing greater movement of the wire mesh. In addition, the load on the anchor A3 can be reduced by the extension rope 16 coming out. Therefore, it functions as a "shock absorber in which the extension rope (side connecting rope) extends in length while absorbing energy, but does not have a stopper mechanism for maintaining the connection."

6A and 6B are diagrams showing the first shock absorber 18, with FIG. 6A being a diagram showing the attached state, and FIGS. 6B to 6D being diagrams showing the individual components of the first shock absorber 18.
The first buffer device 18 buffers the tension acting on the upper horizontal rope 13 (or the lower horizontal rope 14),
A plurality of tubular members 181 arranged in series so that tension is applied in the axial direction;
A plurality of washers 182 are disposed between and at the ends of the plurality of tubular members 181;
An edge member 183 which is a member connected to a fixing member such as an anchor (A1/A4) via a connecting metal fitting or the like;
A bracket member 184 slidably inserted into the edge member 183;
A shaft member 185 connected to the upper horizontal rope 13 (or the lower horizontal rope 14) and inserted into the inside of the tubular member 181 and the bracket member 184;
It has the following features.
6(d), the tubular member 181 is a cylindrical member (formed of a steel pipe in this embodiment) and includes a load conversion section 1811 that applies at least a part of a compressive load or a tensile load applied in the axial direction as a bending load (converts a compressive or tensile load into a bending load). As a result, when a load is applied in the axial direction, the load conversion section 1811 first deforms to provide a cushioning function.
The washer 182 is a member for allowing some misalignment between the tubular members 181 (ensuring that the load is appropriately transmitted to each member even if the axis of each tubular member 181 is slightly misaligned). Note that the washer 182 is not necessarily required in cases where the axial misalignment of the tubular members 181 is prevented by a shaft member 185 or the like inserted inside the tubular member 181 and there is no problem with the transmission of the load to each member.
In this embodiment, the edge member 183 is formed of a wire rope. An eye portion 1831 is formed in the center of the wire rope, and the wire rope is passed through two bracket members 184 having holes formed therein for slidably passing through both sides, and stoppers 1832 are formed on both ends of the wire rope. Here, the edge member 183 is formed of a wire rope, but it may be formed of a metal member having a similar function. The stopper 1832 may be formed so as not to come off the bracket member 184. For example, when the edge member 183 is formed as a metal member, a bolt portion formed at the end of the edge member 183 may be passed through the bracket member 184 (through a washer, for example) and secured with a nut.
The bracket material 184 is a member for applying the tension acting on the upper horizontal rope 13 (or the lower horizontal rope 14) to each tubular member 181 by sandwiching the tubular members 181 arranged in series. The bracket material 184 is formed with a hole configured to allow the wire rope of the edge member 183 to pass slidably through but not allow the stopper 1832 to pass through (butt against) it. Also, a hole is formed with a hole configured to allow the shaft member 185 to pass slidably through but not allow the washer 182 (or tubular member 181) to pass through (butt against) it.
In this embodiment, the shaft member 185 is formed of a wire rope, and an eye is formed at one end by using a wire grip or the like to connect to the eye formed at the end of the upper horizontal rope 13 (or the lower horizontal rope 14), and a stopper 1851 is formed at the other end. The one end of the shaft member 185 before the eye is formed is passed through each member (bracket member 184, tubular member 181, washer 182), and an eye is formed at the one end to connect to the upper horizontal rope 13 (or the lower horizontal rope 14), so that they are assembled as shown in FIG. 6(a). Note that, although the shaft member 185 is formed of a wire rope as an example here, a member having a similar function may be formed as a metal fitting, or the like. Also, the upper horizontal rope 13 (or the lower horizontal rope 14) itself may be used as the shaft member 185. In addition, stopper 1851 may be configured so as not to come off bracket material 184, and may be configured, for example, of a bolt (rod screw) and a nut (and washer) that screws into it, similar to the description of stopper 1832 above.
The first buffer device 18 is configured by combining the above-mentioned components as shown in Figure 6 (a) so that the tension acting on the upper horizontal rope 13 (or the lower horizontal rope 14) is applied as an axial compressive force to the tubular members 181 arranged in series.
In the first shock absorber 18, each tubular member 181 is gradually crushed in response to tension based on the impact energy of the impact of a rockfall, and functions to send out the upper horizontal rope 13 (or the lower horizontal rope 14) accordingly. When each tubular member 181 is completely crushed, the upper horizontal rope 13 (or the lower horizontal rope 14) is held back at that point. Therefore, the first shock absorber 18 functions as a "shock absorber that extends in length while absorbing energy, while maintaining connection by a stopper mechanism."
The first shock absorber 18 can easily adjust the shock absorber performance by changing the number of tubular members 181. In this embodiment, the same first shock absorber 18 is used for the upper horizontal rope 13 and the lower horizontal rope 14, but by arranging a larger number of tubular members 181 on the upper horizontal rope 13, the upper horizontal rope 13 is configured to have a higher shock absorber capacity.

In order to attach the wire mesh 11 in a way that makes use of its flexible structure, the protective net 1 of this embodiment has an "upper wire mesh pay-out structure that is configured so that, when the wire mesh is attached to the top of the support pillar, the wire mesh is paid out from the top of the support pillar when impact energy from a falling rock or the like is applied to the wire mesh."
The upper wire mesh pay-out structure includes a wire mesh 11 slidably attached to the upper horizontal rope 13, and a wire mesh 11 not being connected to the vertical rope 15 within a predetermined range downward from the top of the support 12.
The upper part of the wire mesh 11 is attached to the upper horizontal rope 13 by folding back the part of the upper end of the wire mesh 11 described above which is made up of a single piece of wire mesh (the protruding part of one of the wire meshes) so as to wrap around the upper horizontal rope 13, and fastening the folded back part to the wire mesh 11 with a fastening coil, thereby allowing the upper part of the wire mesh 11 to be slidably attached to the upper horizontal rope 13.
In addition, on both sides of the wire mesh 11, the vertical ropes 15 are fastened to the wire mesh 11 by fastening coils, and each extension rope 16 is connected to this vertical rope; however, from the top of the support pillar to the uppermost extension rope 16 among the multiple extension ropes 16 (range L1 in Figure 2), the wire mesh 11 is not connected to the vertical ropes 15 (the vertical ropes 15 are fastened to the wire mesh 11 by fastening coils in the range L2).
This allows freedom of movement at the upper part of the wire mesh 11, and as will be seen in the experimental results described later, when impact energy from a falling rock or the like is applied to the wire mesh 11, the wire mesh 11 is unfolded (see the area circled in white in the third photograph from the top of the sequence of photographs in Figure 10), allowing the wire mesh 11 to deform flexibly and overall, and the impact energy is efficiently absorbed by the entire wire mesh 11.
In addition, the sending-out function of the first buffer device 18 of the upper horizontal rope 13 and the sending-out function of the second buffer device 17 of the extension rope 16 described above also function as an upper wire mesh pay-out structure.

In addition, in order to attach the wire mesh 11 in a way that makes use of its flexible structure, the protective net 1 of this embodiment also has a "lower wire mesh pay-out structure that is configured so that, when the lower side of the wire mesh is attached, the lower side of the wire mesh is paid out when impact energy from a rockfall or the like is applied to the wire mesh."
The lower wire mesh pay-out structure includes a wire mesh 11 slidably attached to the lower horizontal rope 14, and a wire mesh 11 not connected to the vertical rope 15 within a predetermined range upward from the connection position of the vertical rope 15 to the lower horizontal rope 14.
The lower part of the wire mesh 11 is attached to the lower horizontal rope 14 by folding back the part at the lower end of the wire mesh 11 described above, which is made up of a single piece of wire mesh (the protruding part of one of the wire meshes), so as to wrap around the lower horizontal rope 14, and fastening the folded back part to the wire mesh 11 with a fastening coil, thereby allowing the lower part of the wire mesh 11 to be slidably attached to the lower horizontal rope 14.
Furthermore, in the range (range L3 in Figure 2) where the wire grips used to form the eye portions for connecting the vertical ropes 15 to the lower horizontal ropes 14 are located, the wire mesh 11 is not connected to the vertical ropes 15 (the vertical ropes 15 are fastened to the wire mesh 11 by fastening coils in the range L2).
This allows freedom of movement in the lower part of the wire mesh 11, and as will be shown in the experimental results described later, when impact energy from a falling rock or the like is applied to the wire mesh, the wire mesh 11 is unrolled (see the area circled in white in Figure 10), allowing the wire mesh 11 to deform flexibly and overall, and the impact energy is efficiently absorbed by the entire wire mesh 11.
In addition, the sending-out function of the first buffer device 18 of the lower horizontal rope 14 and the sending-out function of the second buffer device 17 of the extension rope 16 described above also function as a lower wire mesh pay-out structure.

The anchors (A1-A5) to which the upper horizontal ropes 13, lower horizontal ropes 14, extension ropes 16 and each stay rope are connected have connection parts at their heads, and are driven into the slope to connect the ropes to hold (fix) each component. Various types of anchors can be used for the anchors (A1-A5), and an appropriate one can be selected depending on the condition of the strata where they are driven and the required strength. Similarly, any conventionally used attachment materials and methods can be used for the materials and methods used to attach each component to the anchors.

The above-described construction method of the protective net 1 is as follows:
a step of erecting each of the supports 12 on a slope and supporting the supports with each of the stay ropes;
A step of installing each anchor (A1 to A5);
a step of suspending the upper horizontal rope 13 over the upper portions of the two posts 12 and connecting the upper horizontal rope 13 to the anchor A2 via the first shock absorber 18;
A step of installing the wire mesh 11 on the upper horizontal rope 13;
A step of connecting the vertical ropes 15 on both sides to the upper part of the support 12;
A step of connecting the lower horizontal rope 14 to the anchor A4 via a first buffer device 18;
A step of connecting the vertical ropes 15 on both sides to the lower horizontal ropes 14,
A step of attaching the wire mesh 11 to the lower horizontal ropes 14 and the vertical ropes 15;
Connecting each extension rope 16 to the vertical rope 15 and the anchor A3 via a second buffer device 17;
has.
The above steps are merely an example, and some of the steps may be changed in order.

In the process of fastening the wire mesh 11 to the upper horizontal rope 13,
At the installation site of the protective net, one of the two wire meshes constituting the double structure of the wire mesh 11 is lifted to a predetermined height, and the other wire mesh is fastened to the lifted wire mesh by a fastening coil;
A step of further lifting up one of the wire meshes to which the other wire mesh is fastened and attaching it to the upper horizontal ropes 13;
has.
FIG. 7 is a photograph showing the installation of the protective net (test specimen) of this embodiment used in the experiment described below.
As shown in the two upper photographs of Fig. 7, the first wire mesh 111 is lifted by a crane to a predetermined height (a height at which the upper end of the second wire mesh 112 can be easily attached), and the upper end of the second wire mesh 112 is fastened to the wire mesh 111 using the fastening coil C2. At this time, temporary fastening using wire makes it easier to fasten the fastening coil C2.
Once the upper end of wire mesh 112 has been fastened to wire mesh 111, wire mesh 11 (wire mesh 111 and wire mesh 112) is lifted up by further lifting it with a crane, as shown in the two lower photographs of Figure 7. Once the lower end of wire mesh 112 has been lifted up to a predetermined height (a height at which it is easy to attach the lower end of wire mesh 112), the lower end of wire mesh 112 is fastened to wire mesh 111 using a fastening coil (not shown in particular).
Then, the wire netting is moved to a height and position where it can be attached to the upper horizontal ropes 13, and the upper end of the wire netting 111 is folded back to surround the upper horizontal ropes 13, and the folded back portion is fastened with a fastening coil. (Furthermore, the lower end of the wire netting 111 is folded back to surround the lower horizontal ropes 14, and the folded back portion is fastened with a fastening coil, and the wire netting is fastened to the vertical ropes 15 on both sides with fastening coils.)
As can be seen from the photograph in Figure 7, the above construction method allows for a continuous flow of work from the rolled-up wire mesh brought to the site to the formation and installation of the double-layered wire mesh, resulting in excellent work efficiency.
In addition, when using multiple wire meshes (11a, 11b, 11c) in the width direction as in this embodiment, the wire meshes arranged in the width direction may be lifted up by a crane at the same time, or may be lifted up one by one (the above operation is repeated multiple times). If multiple wire meshes are lifted up at the same time, the operation of fastening adjacent wire meshes in the width direction with the fastening coil C1 can be performed while gradually lifting them up, which is excellent in work efficiency.

As described above, the protective net 1 of this embodiment makes it possible to more efficiently utilize the cushioning properties of the wire mesh itself and to give the blocking surface a simple structure, thereby reducing the number of parts and simplifying installation work.
Due to the absence of a horizontal rope or other cord connected to a fixing member such as an anchor on the blocking surface and the above-described upper wire mesh pay-out structure and lower wire mesh pay-out structure, the movement of the entire wire mesh having a flexible structure is made more efficient, as shown in the following collision experiment (FIG. 10), and it can be said that the wire mesh has weak strength locally because the wire material is thinner than the horizontal rope or other cord, but the wire mesh has high potential in terms of energy absorption capacity as a whole. The protective net 1 of this embodiment makes it possible to efficiently transmit impact energy (distribute load) to the entire wire mesh by making the movement of the entire wire mesh more efficient, thereby demonstrating high cushioning capacity of the entire wire mesh.
At the same time, since it has a simple structure in which no ropes such as cross ropes connected to fixing members such as anchors are placed at the blocking surface, the number of parts is reduced and installation is simplified, thereby improving ease of installation and cost-effectiveness.

In the embodiment, an example has been described in which the blocking surface has two layers of wire mesh, but the present invention is not limited to this. If the required strength can be obtained with a single wire mesh, it may be a single-layer structure, or three or more layers of wire mesh may be layered (note that a wire mesh with three or more layers also has a double structure, and therefore the concept of ``a wire mesh with a double structure'' includes wire mesh with three or more layers).
In addition, although the embodiments use a high-strength wire mesh formed using high-tensile wire rod with a tensile strength of 1400 MPa or more, it is also possible to use a wire mesh formed from wire rod with a lower tensile strength (for example, three or more layers of this).

In the embodiment, the wire mesh 11 is not connected to the vertical ropes 15 in the range (range L3 in Figure 2) where the wire grips used to form the eye portions for connecting the vertical ropes 15 to the lower horizontal ropes 14 are located, but the wire mesh 11 may not be connected to the vertical ropes 15 between the lower end of the vertical ropes 15 and the lowest extension rope 16 among the multiple extension ropes 16.

In the embodiment, the protection net according to the present invention has been described as a protection against falling rocks, but it can also be used to protect against overhanging snow, avalanches, landslides, and more.

(Protection net weight impact experiment)
Next, a weight impact test performed on the protective net 1 described in the embodiment and the results thereof will be described.
The upper diagram in Figure 8 shows the specifications of the experimental specimen (protective net 1) used in this test, and the lower photographs are front and side photographs showing the installed state of protective net 1.

Experimental conditions As shown in Figure 9, a steel frame was made and a test specimen (protective net 1) was placed on the frame so that the weight projecting from the rail injection port was perpendicular to the blocking surface of the test specimen. The weight (weight shown in the upper left of Figure 9) was hoisted up to a specified height from the injection port rail with a winch and fixed to the air-type release device. After preparations were completed, the valve was opened to operate the release device, causing the weight to slide and collide with the test specimen. The weight speed was measured by reading the full length of the weight with a high-speed camera.
Test method: Slope slide method Weight shape, material and weight: W = 2.9t (EOTA type, polyhedral steel shell with concrete, with wheels)
Weight speed: V=31.2m/s
Wire mesh angle: θ = 88°

Experimental Results Figure 10 shows the overall situation before and after the blocking surface was subjected to maximum displacement and capture due to the impact of the weight, divided into frames.
As can be seen from the sequence of photographs in FIG. 10, when the weight strikes the wire mesh, it flexibly deforms to capture the weight and absorb the impact energy.
There are no vertical or horizontal ropes connected to anchors or the like on the blocking surface, and as can be seen from the area circled in white in the third photograph from the top of the sequence of photographs in Figure 10, the wire mesh is unwound by an upper wire mesh unwinding structure and a lower wire mesh unwinding structure, which allow the wire mesh to flexibly deform.

Summary of the experiment results No breaks were found in the two-layered wire mesh near the impact, and the weight energy of 1,409 kJ was captured. However, some breaks were found in the wire mesh between the single-layered structure and the folded-back part of the upper horizontal rope.
The upper, lower, retaining and vertical ropes were all in good condition.
The sliding condition of both ends of the upper folded wire mesh was checked.
The wire mesh in the collision area showed both vertical and horizontal deformation.
The first shock absorber confirmed partial and full shock absorbency.
A certain amount of slippage was confirmed in the buffer grip (second buffer device) of the extension rope near the collision point (some ropes were also found to have come loose).
Although there was an indentation at the top of the support pillar caused by the upper horizontal rope slipping, there was no other harmful installation angle and no deformation due to bending and compression was observed.
The cushioning coils were installed on both ends of the collision, but the side near the protruding rope attachment on the blocking surface had the greatest effect.

1. . . Protective net 11. . . Wire mesh 12. . . Support P1, P2... Rope arrangement path 13. . . Upper horizontal rope (upper wire mesh holding rope)
14. Lower horizontal rope (lower wire mesh holding rope)
15. Vertical rope (side connecting member)
16. Extension rope (side connecting rope)
17. Second shock absorber 171. Eye portion 172. Spiral portion 18. First shock absorber 1.
A1 to A5... Anchor

Claims

A protective net installed on a slope,
Multiple pillars and
A wire mesh suspended from an upper portion of the support toward a downward slope, the wire mesh having a rope connected to a fixing member that is not disposed on a blocking surface;
an upper wire mesh payout structure configured to pay out the wire mesh when impact energy from a rockfall or the like is applied to the wire mesh during attachment of the wire mesh to the upper portion of the support;
A protective net.
The upper wire mesh payout structure is
An upper wire mesh holding cord that is hung over the upper part of the support and slidably holds the upper part of the wire mesh;
a side connecting member extending in the vertical direction at the side of the wire mesh and connecting the side of the wire mesh to a side connecting rope having one end connected to an anchor, the side connecting member being connected to the upper part of the support pole and not connected to the wire mesh within a predetermined range downward from the upper part of the support pole;
2. The protective net of claim 1, comprising:
The protective net of claim 2, wherein the side connecting member is connected to a plurality of the side connecting ropes, and the predetermined range is between the top of the support pole and the uppermost side connecting rope among the plurality of the side connecting ropes.
The protective net of claim 1, which is provided with a lower wire mesh payout structure that is configured to pay out the lower side of the wire mesh when impact energy from a rockfall or the like is applied to the wire mesh.
The lower wire mesh payout structure is
A lower wire mesh holding cord that slidably holds a lower portion of the wire mesh;
a side connecting member extending in the vertical direction at the side of the wire mesh and connecting the side of the wire mesh to a side connecting rope having one end connected to an anchor, the side connecting member being slidably connected to the lower wire mesh holding rope and not connected to the wire mesh within a predetermined range upward from the connection position to the lower wire mesh holding rope;
5. The protective net according to claim 4, which is constructed by:
The protective net of claim 5, wherein the side connecting member is a rope, an eye is formed at the lower end of the rope by a wire grip for connecting to the lower wire mesh holding rope, and the predetermined range is the range from the connection position to the lower wire mesh holding rope to where the wire grip is located.
The upper wire mesh holding rope body has a first buffer device that absorbs energy while expanding in length and maintains the connection by a stopper mechanism, and is connected to the anchor;
3. The protective net according to claim 2, wherein the side connecting ropes have a second shock absorber that does not include a stopper mechanism for maintaining the connection while expanding in length while absorbing energy.
The lower wire mesh holding rope body has a first buffer device that absorbs energy while expanding in length and maintains the connection by a stopper mechanism, and is connected to the anchor;
6. The protective net according to claim 5, wherein the side connecting ropes have a second shock absorber that does not include a stopper mechanism for maintaining the connection while expanding in length while absorbing energy.
The protective net according to claim 7 or 8, wherein the second shock absorber is formed by a band of multiple strands, the band is bent at its center to form an eye section, and two spiral sections extend from the eye section, the side connecting rope is wound around the two spiral sections with excess length, and when impact energy from a rockfall or the like is applied, the wound section slides with friction.
The protective net according to any one of claims 2, 3, and 7, which has two cable arrangement paths at the top of the support posts through which the upper wire mesh holding cable can slide.
The protective net according to any one of claims 1 to 8, wherein the wire mesh has a double structure.
An upper wire mesh holding cord is provided which is hung over the upper part of the support pole,
A protective net as described in claim 11, wherein one of the two wire meshes that make up the double structure protrudes upward above the other wire mesh, and the protruding portion of the one wire mesh is folded back so as to wrap around the upper wire mesh holding cord, thereby allowing the upper part of the wire mesh to be slidably held by the upper wire mesh holding cord.
a lower wire mesh holding cord that slidably holds a lower portion of the wire mesh;
A protective net as described in claim 11, wherein one of the two wire meshes constituting the double structure protrudes downwardly beyond the other wire mesh, and the protruding portion of the one wire mesh is folded back so as to wrap around the lower wire mesh holding rope, thereby allowing the lower part of the wire mesh to be slidably held by the lower wire mesh holding rope.
A method for installing a protective net according to claim 12, comprising the steps of:
At the installation site of the protective net, one of the two wire meshes constituting the double structure is lifted to a predetermined height, and the other wire mesh is fastened to the lifted wire mesh by a fastening coil;
a step of further lifting the one wire mesh to which the other wire mesh is fastened and attaching it to the upper wire mesh holding cord;
A method for constructing a protective net comprising the steps of: