JP6844765B2 - Rings for ring nets, ring nets formed by connecting them, and rockfall protection fences using them - Google Patents

Description

The present invention relates to a ring for a ring-type net, a ring-type net formed by connecting the rings, and a rockfall protection fence using the ring-type net.

It is necessary to consider the risk of landslides and rockfalls in areas below slopes such as mountains, and the risk of disasters caused by flying objects in facilities that store dangerous materials and dangerous equipment. Guard fences are used to prevent such disasters. For example, Patent Documents 1, 2 and 3 disclose a protective fence for falling rocks, and disclose an example using a ring-type net.

FIG. 7 is an example of a rockfall protection fence using a ring-type net disclosed in Patent Document 3, and as shown in the figure, a plurality of columns 16 are provided at required locations on a slope such as a mountain, and a foundation 26 is provided for each. Is erected and erected, and an upper holding rope 18 for holding the upper edge of the net is bridged between the upper positions of the respective columns 16. Similarly, a lower holding rope 20 for holding the lower edge portion of the net is laid between the lower positions of the respective columns 16. A ring-type net 22 for receiving rockfall and the like is installed between the upper and lower holding ropes 18 and 20.

Each of the above-mentioned columns 16 can be inclined to the valley side by a hinge portion provided at a lower position, and a retaining rope 28 for regulating this inclination within a predetermined range is installed at a predetermined position on the mountain side slope. It is suspended between the anchor 36 and the upper end of each column 16. Side ropes 30 are also stretched on the sides of the columns 16 at both ends between the anchors 36 installed at predetermined positions on the mountain side slope and the columns 16 at both ends.

FIG. 8 shows an example of one ring of the above ring-type net (FIG. 8A) and a ring-type net combining the rings (FIG. 8B). The ring 24 is bound by using a binding tool 12 at three locations on the circumference of the ring 24, which are equally divided around the metal wire 25. The wires 25 are in close contact with each other without any gaps.

As shown in FIG. 8B, the ring-type nets 22 are connected to each other in a state where the rings 24 are in contact with each other on the inner peripheral side, that is, in a relationship of being inserted into the rings.

Further, the holding ropes 18 and 20, the retaining rope 28 and the side rope 30 shown in FIG. 7 are each provided with a brake device 32. FIG. 9 is a schematic perspective view of the brake device. The brake device 32 includes a loop pipe 38 and a tightening member 40, and the holding ropes 18, 20 and the retaining rope 28 are inserted into the loop pipe 38 in the middle. Both ends of the loop tube 38 are superposed in parallel, and the superposed portion is compacted by a tightening member, for example, a compression sleeve 40. When the impact force due to falling rocks spreads to the holding ropes 18 and 20 and the retaining rope 28 and an abnormal tension is generated in these ropes, a force acts in the direction of reducing the diameter of the loop pipe 38, and both ends of the loop pipe 38 are affected. Receives forces in opposite directions along the rope. When the force applied to the rope exceeds the frictional force between the loop pipes 38 and between the loop pipes 38 and the compression sleeve 40 at the compaction point by the compression sleeve 40, slippage occurs between the loop pipes 38 and the kinetic energy due to the impact is absorbed. ..

When the falling rock hits the ring-type net 22 of the protective fence, the net 22 is deformed and the energy of the falling rock is partially absorbed. When the energy of falling rocks is higher, the circular ring 24 is deformed until it finally becomes a substantially quadrangle. Further, the energy of falling rocks is also transmitted to the upper and lower support ropes 18 and 20 and the reserve rope 28, the brake device 32 is operated, and each column 16 falls to the valley side and the energy is absorbed. FIG. 10 shows the situation. It can be seen that the ring-type net 22 is greatly deformed by the falling rock 200, the brake device is activated, and the support column 16 is inclined toward the valley side.

Japanese Patent No. 5479677 Japanese Patent No. 4916968 Japanese Patent No. 3131566

As described above, in the rockfall protection fence 41 using the conventional ring type net 22, when the rockfall hits the ring type net 22, the rings 24 are deformed and the brake device 32 operates to absorb the energy of the rockfall. It has become. That is, the energy of falling rocks is dispersed and absorbed by the ring type net 22 and the braking device 32. In the ring 24 of the ring-type net 22, the wires 25 constituting the ring 24 are wound together without any gaps, and the process of receiving a rock fall or the like and extending in the falling direction of the rock fall or the like and finally transforming from a circular shape to a substantially quadrangular shape. Absorbs energy with. In this energy absorption, the ring-type net 22 begins to expand due to the deviation of the ring 24 and expands, and then a large amount of energy is absorbed in the process of deforming each ring 24 from a circle to a substantially quadrangle. Therefore, the amount of energy absorbed is small in the process before the deformation of the ring 24 from the circular shape to the substantially quadrangular shape begins. Further, from the viewpoint of restoration and repair of the protective fence after falling rocks, it is desirable to increase the amount of energy absorbed by the ring-type net 22 and reduce the amount of operation of the brake device 32 as much as possible.

The present invention has been made in view of the above problems, and an object of the present invention is a ring for a ring-type net capable of increasing the amount of energy that can be absorbed by the ring-type net and suppressing the amount of deformation. It is an object of the present invention to provide a ring type net formed by connecting and a rockfall protection fence using the ring type net.

In order to achieve the above object, the ring according to claim 1 is
A ring that constitutes a ring-type net for a rockfall protection fence and is formed by a wire having a predetermined tensile strength.
The ring is a multi-wire ring in which a plurality of substantially circular strands having substantially the same circumference are stacked, and is configured to be bound at a plurality of places, and the binding is made up of the bound strands. The wire is made movable against a predetermined frictional resistance, and the lengths of the strands between the binding portions are set to different lengths.

According to this configuration, the multiple strands constituting the ring have a configuration in which the respective strands have substantially the same peripheral length, but the lengths between the binding portions are different from each other. Therefore, for example, when an impact such as falling rock is applied to the ring-type net formed by the ring of the present invention, the impact energy is transmitted to each ring configured as the multiple strand ring. At this time, tension acts on each ring, and the substantially circular strands constituting the ring are set to different lengths between the binding portions, so that each strand is the length between the binding portions. Try to shift to the same state. This shift movement is performed at the binding point against a predetermined frictional resistance. Therefore, in the deformation action of the ring type net caused by the impact such as falling rocks, that is, in the stage before each ring is finally deformed into a substantially quadrangle or in the deformation process thereof, the braking action due to the displacement movement in each ring is exhibited. To. As a result, even if the ring-type net is composed of rings having the same diameter as the conventional one, the amount of energy such as falling rocks absorbed in the process until the final deformation state due to the impact becomes larger, and the ring-type net becomes larger. The amount of deformation can be suppressed as much as possible.

The ring according to claim 2 is the ring according to claim 1, wherein the multiple strand ring is formed by winding the strands a plurality of times. This configuration makes it easier to quickly manufacture a multi-wire ring and further to manufacture a ring-type net using the ring.

The ring according to claim 3 is the ring according to claim 1, wherein the multiple strand ring is formed by superimposing a plurality of circular strands. In this configuration, it is not possible to form a ring-type net with the rings inserted into each other, but the ring itself can be manufactured more easily.

The ring according to claim 4 is the ring according to any one of claims 1 to 3, wherein the strands have irregularities on the surface. With this configuration, the predetermined frictional resistance can be adjusted according to the size, shape, and number of the unevenness. Therefore, a larger frictional resistance is secured at the binding point of the strands, and the magnitude of the resistance can be easily and precisely adjusted.

The ring according to claim 5 is the ring according to any one of claims 1 to 4, wherein the wire is coated on the surface thereof. With this configuration, the predetermined frictional resistance can be adjusted by the physical properties of the coating material. Therefore, the frictional resistance can be easily adjusted without changing the shape of the ring itself.

The ring according to claim 6 is the ring according to any one of claims 1 to 5, and the material of the binding tool for binding the strands is from a material having a hardness or strength lower than that of the strands. It is characterized by being selected. With this configuration, the predetermined frictional resistance can be easily and precisely adjusted by the hardness or strength of the material of the binding tool.

In order to achieve the above object, the ring-type net for the rockfall protection fence according to claim 7 is formed by connecting the rings according to any one of claims 1, 2, 4 to 6. In a ring-type net for a fence, the rings are connected so that the rings are in contact with each other on the inner peripheral side. With this configuration, the energy absorption action in the process of deformation of the ring-type net for the rockfall protection fence against the impact is greatly increased by the braking action of each ring as a whole. Therefore, the protective function of the equipment using the ring-type net for the rockfall protection fence is improved.

The ring-type net for a rockfall protection fence according to claim 8 is a ring-type net for a rockfall protection fence formed by connecting the rings according to any one of claims 1 to 6 , wherein the ring-type net is of the ring. The connection is characterized by using a coupling tool that connects adjacent rings. With this configuration, by forming each ring in advance and then performing the joining work of each ring, it is possible to manufacture a ring-type net for a rockfall protection fence in which the braking action of each ring is increased.

In order to achieve the above object, the rockfall protection fence according to claim 9 is
A rockfall protection fence using the ring-type net according to claim 7 or 8.
For holding a net stretched between a row of columns consisting of a plurality of columns arranged on a slope at predetermined intervals over a required length range and fixed to the ground, and an upper position of each column of the column. The ring-type net has an upper holding rope of the above and a lower holding rope for holding a net stretched between the lower positions of the respective columns of the column row, and the upper side of the ring type net is raised by the upper holding rope. It is characterized in that it is installed in a state where the lower side is held by the lower holding rope.

With this configuration, by using a ring-type net that secures a larger amount of energy absorption than before, the rockfall receiving function of the rockfall protection fence as a whole is further improved. Therefore, the amount of brake devices installed on the entire fence can be reduced, and the amount of extension for those brake devices can be reduced, facilitating the overall construction work of the rockfall protection fence.

The rockfall protection fence according to claim 10 is the rockfall protection fence according to claim 9.
One or a plurality of columns stretched between at least two columns of the plurality of columns at a height position between the upper side and the lower side of the ring-type net from one column of the at least two columns to the other column. It is characterized by having a reinforcing rope of.

With this configuration, in the initial stage of receiving an impact such as falling rocks, the reinforcing rope first disperses and absorbs energy such as falling rocks. Therefore, the ring-type net with increased braking action absorbs the remaining energy absorbed by the reinforcing rope, and the amount of deformation can be suppressed to be smaller by the synergistic effect of both, and the ring-type net can be effectively used. It can be used.

According to the present invention, a braking action is added when a force is applied to the ring for the ring-type net, and the energy absorption action of the ring-type net and the rockfall protection fence formed by using these rings as a whole is performed. It will increase significantly. As a result, the protective function of the ring-type net and the rockfall protection fence is improved, and the safety of the dangerous area is more accurately ensured.

It is a schematic explanatory drawing of the ring concerning the protective ring of this invention. It is a schematic explanatory drawing which shows another example of the wire | wire which constitutes the ring with respect to the protective ring of this invention. However, FIG. 2A shows a wire having irregularities formed on the surface of the wire, and FIG. 2B shows a wire having a small diameter wound around the surface of the wire. A schematic front view of a ring-type net connecting the rings shown in FIG. 1 is shown. However, FIG. 3 (A) shows the method by the inner peripheral coupling method, and FIG. 3 (B) shows the method by the outer peripheral surface coupling method. It shows how the ring-type net of FIG. 1 is deformed by being impacted. FIG. (A) is a schematic front view before deformation, FIG. (B) is a schematic front view showing how the ring exerts a braking effect, and FIG. It is a schematic front view which shows the appearance of being transformed into a quadrangle. The relationship between the amount of deformation of the ring of the ring type net and the amount of energy absorption is shown. It is a schematic perspective view of the rockfall protection fence used for the ring type net of this invention. It is a schematic front view of a rockfall protection fence using a conventional ring type net. Regarding an example of the ring of the conventional ring type net, FIG. 6A shows a schematic front view of the ring, and FIG. 3B shows a schematic front view of the ring type net connecting the rings. A schematic perspective view of the brake device used for the rockfall protection fence shown in FIG. 7 is shown. It is explanatory drawing which shows the state that the brake device of the rockfall protection fence of FIG. 7 was operated.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic front view of a ring forming a ring-type net for a rockfall protection fence.

The ring 10 is formed by winding a metal wire 11 around four circumferences, and is bound by a binding tool 12 at three equidistant locations on the circumference. The circumference of each winding wire is set to be substantially the same length, but as shown in the figure between the binding tools 12, the length is short and the wire 11 protruding inside the ring 10 and the wire 11 There is a wire 11 that has an extra length and protrudes to the outside of the ring 10. Quantitatively showing the difference in the length of the wire 11 between the binding tools 12, the portion that is about 0 to 15% longer than the conventional case where the wire is tightly wound and from about 0 There is a part that is shortened by 15%. Preferably, the difference in length between the binders 12 of the strands 11 is about 0 to 10%.

The strands 11 are bound by the binding tool 12 in a state in which the strands 11 can be moved by a predetermined frictional force. The tensile strength of the metal wire 11 and the predetermined frictional resistance at the binding point are determined by assuming the total energy such as falling rocks received by the ring type net 14. In the present embodiment, the wire 11 is a steel wire made of a steel wire, the wire diameter is 3 mm to 4 mm, and the tensile strength is 800 N / mm 2 or more. The diameter of the ring 11 is about 15 cm to 50 cm. The binding tool 12 is a so-called C-creep (C-type stop ring) or O-type stop ring made of aluminum, and is a material having a hardness or strength lower than that of the wire 11. As the wire 11, an iron wire of a mild steel wire may be used. The material constituting the binding tool 12 may be steel.

When the ring 10 receives energy such as falling rocks, each of the bound wires 11 moves against a predetermined frictional resistance at the bound portion so that the lengths of the respective strands 11 between the bound portions are the same. In this process, the energy absorption effect increases. There are two types of frictional resistance: the frictional resistance between the strands 11 and the strands 11, and the frictional resistance between the strands 11 and the binding tool 12. The frictional resistance between the strands 11 and the strands 11 can be adjusted by applying irregularities or the like to the surface of the strands as described later, and the frictional resistance between the strands 11 and the binding tool 12 is as described above. Similarly, the surface of the wire 11 can be made uneven, and the hardness and strength of the material of the binding tool 12 can be adjusted.

FIG. 2 shows an example of another embodiment of the strands used to form the ring of the present invention. FIG. 2A shows a concave portion 11a and a convex portion 11b formed on the surface of the wire 11. It is possible to precisely adjust the predetermined frictional resistance between the strands 11 and the strands 11 and between the strands 11 and the binding tool 12 depending on the number, size, shape and the like of the irregularities. FIG. 2B shows a wire 11-2 having a small diameter wound around the steel wire 11-1. By winding the wire 11-2, irregularities are formed on the surface of the steel wire wire 11-1, which makes it possible to adjust the frictional resistance.

In the present embodiment, as described above, the binding tool 12 has a hardness or strength lower than that of the wire 11. That is, with this configuration, collision energy such as falling rocks is applied to the wire 11, and when the wire 11 tries to move at the place where it is bound by the binding tool 12, the wire 11 becomes easy to move, and the ring The braking action at the time of initial deformation of 10 can be enhanced.

When the tensile strengths of the strands 11 and the binding tool 12 are substantially the same, by applying the paint to the strands 11, the strands 11 and the strands 11 and the strands 11 and the strands depending on the physical properties of the material of the paint, for example, the viscosity, etc. It is possible to adjust the frictional resistance between 11 and the bundling tool 12. Further, the wire 11 may be covered with a resin to adjust the frictional resistance. By applying paint or resin, the anticorrosion effect of the wire 11 is also improved. For corrosion protection, other zinc plating or zinc and aluminum plating may be applied.

FIG. 3A shows a part of a ring-type net in which the rings 10 of FIG. 1A are connected in a state of being in contact with each other on the inner peripheral side. It is an inner peripheral coupling method, which is a normal net manufacturing method, and a net can be easily formed. On the other hand, FIG. 3B shows a part of a ring-type net in which each ring 10 is connected by using a coupling tool 13 in a state of being in contact with or facing each other on the outer peripheral side. This is an outer peripheral surface coupling method, and a shackle 13 can be used as the coupling tool 12, for example, as shown in the drawing. The advantage of the outer peripheral surface coupling is that, for example, the ring type net 14 can be easily repaired or expanded, and the repaired ring type net can also exert an increased braking action.

FIG. 4 illustrates how the ring-type net 22 is deformed due to falling rocks. The figure (A) is before deformation. When the ring-type net 14 receives a rock fall, a force is applied to each of the strands 11 constituting the ring 10. Since each of the strands 11 is set to a different length between the binding points, it tries to move at the binding point by receiving a force. Eventually, the lengths of the strands between the binding points will be the same. FIG. 3B shows this state.

That is, when a rock fall or the like collides with the ring type net 14 formed by the ring 10 of the present invention, the collision energy is transmitted to each ring 10. At this time, tension acts on each ring 10, and the substantially circular strands 11 constituting the ring 10 are set to different lengths between the binding portions, so that the strands 11 are bound. It shifts and moves to a state where the lengths between the binding points are the same against a predetermined frictional resistance at the points. Therefore, in the initial deformation stage of the ring-type net 14, the braking action due to the displacement movement in each of the above-mentioned rings 10 is exerted. Therefore, in the process until the ring-type net 14 becomes a substantially quadrangular shape of the final deformation due to the impact, rock falls. Etc. are effectively absorbed.

FIG. 4C shows a state immediately before the brake device is activated, in which the ring 10 changes from a circular shape to a substantially quadrangular shape of the final deformation due to an impact. In practice, the deformation of FIG. 4 (B) and the deformation of FIG. 4 (C) are performed substantially simultaneously. At the stage from the circular shape to the substantially quadrangle of the final deformation, the integrated energy absorption amount in the ring type net 14 up to that stage is large.

FIG. 5 is a diagram showing the relationship between the amount of deformation of the ring and the amount of energy absorption. The horizontal axis is the amount of deformation of the ring, and the vertical axis is the amount of energy absorption (reaction force). In the conventional ring 24, as described in the background art, there is little deformation in the initial deformation stage, and energy is rapidly absorbed at the stage of changing from a circle to a substantially quadrangle. On the other hand, in the ring 10 of the present invention, energy is absorbed by the movement of each wire 11 from the initial deformation stage, and the braking action is performed. Therefore, the ring 10 of the present invention can absorb a large amount of energy by the time the braking device operates at point A, as compared with the conventional ring 24. That is, the integrated energy absorption amount with respect to the ring deformation amount is larger in the ring 10 of the present invention than in the conventional ring 24. Therefore, in the rockfall protection fence using the conventional ring-type net 22, the deformation of the ring-type net 22 of the present invention is suppressed to be smaller even if the rockfall energy is on the scale of operating the braking device. By this suppression, the occurrence of inconvenience due to the deformation of the ring type net 22 to the facility or the like existing in the installation area of the ring type net 22 is avoided. Further, the resetting work of the ring type net 22 after a disaster becomes easier.

FIG. 6 is a schematic perspective view showing a rockfall protection fence 15 according to an example of the embodiment of the present invention. As shown in the figure, a plurality of columns 16-1 to 16-n to be installed are fixed to the ground at substantially equal height positions on the slope at predetermined intervals over a required length range. The columns 16-1 to n are attached to a base 42 fixed to the ground via a hinge portion 34, and the support columns 16 are tilted at least toward the valley side (opposite to the mountain side) by the hinge portion 34. It is said that it can be tilted. Generally, the heights of the columns 16-1 to n are about 2 m to 5 m, the installation intervals are about 5 m to 10 m, and their sizes and the lengths of the columns are appropriately selected depending on the scale and conditions of the slope.

An upper holding rope 18 and a lower holding rope 20 are laid horizontally on the column column using anchors 36-1, 36-2, 44-1 and 44-2, and the upper holding rope 18 and the lower side are laid horizontally. The ring-type net 14 shown in FIG. 3A is stretched between the holding ropes 20 by being supported by a plurality of columns 16-1 to n.

In the present embodiment, the upper holding rope 18, the lower holding rope 20, the retaining rope 28, and the support rope 46 are provided with the brake device 32. Further, the reinforcing rope 48 stretched from the support column 16-1 to the support column 16-n at a height position between the upper side and the lower side of the ring type net 14, and the reinforcing rope 48 when a load due to falling rocks is applied. A brake device 50 that allows elongation within a predetermined range is provided.

As shown in the figure, there are three reinforcing ropes 48 between the two columns 16-1 and 16-n at both ends of the plurality of columns 16-1 to n in the column row, and one of the columns 16-1 to the other. It is laid horizontally over the columns 16-n. As the reinforcing rope 48, a wire having rigidity or the like can be used, and for example, a rope having a tensile strength of 500 to 2000 N / mm 2 and a diameter of 1 to 4 cm is preferable. The reinforcing rope 48 passes one ring 10 of the ring type net 14 from the mountain side (back side) to the valley side (front side), and then passes the other ring 10 from the valley side (front side) to the mountain side (back side). , So-called sewn, and the tensioning position of the reinforcing rope 48 is maintained.

According to the rockfall protection fence 15 of the present embodiment, immediately after the rockfall collision, the rockfall collision energy is dispersed and absorbed by the ring type net 14 and the reinforcing rope 48 having the increased braking action. The reinforcing rope 48 begins to be deformed immediately after receiving a rock fall, the brake device 50 operates, energy such as the rock fall is absorbed, and at the same time, the energy of the rock fall is transmitted to the ring type net 14 and the collision energy of the rock fall is absorbed. Will be done. Therefore, the energy absorption amount (resistance) of the entire rockfall protection fence 41 increases immediately after the rockfall collision and then rises until the rockfall stops, so that the integrated resistance force catches the rockfall at an earlier stage than before. It is possible to reach a sufficient amount.

Therefore, due to the synergistic effect of the reinforcing rope 48 and the ring-type net 14, the amount of deformation of the ring-type net 14 is suppressed, and the resetting work of the ring-type net 14 after a disaster becomes easier. Further, by suppressing the amount of deformation, it is possible to avoid the occurrence of inconvenience due to the deformation of the ring-type net 14 to the facility or the like existing in the installation area of the ring-type net 14. That is, it is possible to install a rockfall protection fence closer than ever to a house, a road, or the like located in an area below a slope such as a mountain to be protected.

As described above, according to the ring constituting the protective ring-type net of the present embodiment, the ring-type net formed by combining the rings, and the rockfall protection fence using the ring, the ring is formed from the initial deformation stage. It is possible to increase the impact energy such as falling rocks that can be absorbed by. Therefore, even if the scale of rockfall is such that the brake device operates, the amount of deformation of the ring-type net is small in the rockfall protection fence according to the present embodiment, and it is possible that the brake device does not operate after that. Easy maintenance of the guard fence.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the ring constituting the ring type net is not limited to the one in which the steel wire is wound four times and tied at three places.

10, 24 Rings 11, 25 Wires 12 Bundling tools 14, 22 Ring-type nets 15, 41 Rockfall protection fences 16 Struts 18 Upper holding rope 20 Lower holding rope 26 Foundation 28 Reserving rope 30 Side rope 32, 50 Brake device 34 Hinges 36, 44 Anchors 38 Loop pipes 40 Tightening members 42 Bases 46 Supporting ropes 48 Reinforcing ropes

Claims (10)

A ring that constitutes a ring-type net for a rockfall protection fence and is formed by a wire having a predetermined tensile strength.
The ring
It is a multi-wire ring in which a plurality of substantially circular wires having almost the same circumference are stacked, and is configured by being bound at a plurality of places.
The binding is performed in a state in which each of the bound wires can move against a predetermined frictional resistance.
A ring characterized in that the lengths of the strands between the binding portions are set to different lengths. The ring according to claim 1, wherein the multiple wire ring is formed by winding the wire a plurality of times. The ring according to claim 1, wherein the multiple strand ring is formed by superimposing a plurality of circular strands. The ring according to any one of claims 1 to 3, wherein the strand has an uneven surface. The ring according to any one of claims 1 to 4, wherein the wire is coated on the surface. The ring according to any one of claims 1 to 5, wherein the material of the binding tool for binding the strands is selected from those having a hardness or strength lower than that of the strands. In a ring-type net for a rockfall protection fence formed by connecting the rings according to any one of claims 1, 2, 4 to 6.
The ring-type net for a rockfall protection fence is characterized in that the rings are connected so that the rings are in contact with each other on the inner peripheral side. In a ring-type net for a rockfall protection fence formed by connecting the rings according to any one of claims 1 to 6.
A ring-type net for a rockfall protection fence , characterized in that the rings are connected by using a coupling tool that connects adjacent rings. A rockfall protection fence using the ring-type net according to claim 7 or 8.
A row of stanchions consisting of a plurality of stanchions arranged on the slope at predetermined intervals over a required length range and fixed to the ground.
An upper holding rope for holding a net stretched between the upper positions of each of the columns in the column row,
It has a lower holding rope for holding a net, which is stretched between the lower positions of each of the columns in the column row.
The ring type net is
A rockfall protection fence characterized in that the upper side is held by the upper holding rope and the lower side is held by the lower holding rope. One or a plurality of columns stretched between at least two columns of the plurality of columns at a height position between the upper side and the lower side of the ring-type net from one column of the at least two columns to the other column. The rockfall protection fence according to claim 9, further comprising a reinforcing rope of the above.

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