Protective fence

Abstract

To provide a guard fence for capturing falling rocks or the like by a plurality of ropes suspended between columns, capable of reducing cost and labor required for installation and maintenance while obtaining high impact absorbing performance.SOLUTION: A guard fence 10 includes a column row 12 in which columns 20 are erected at predetermined intervals, ropes 30 suspended in the column row in multiple stages at predetermined intervals in the vertical direction, and buffer means 50 attached to the ropes to absorb impact force. At least one end of each rope 30 is folded back at end columns 20-1, 20-4 located at the extreme ends of the column row 12, and a distal end of the rope 30 is engaged with columns 20-2, 20-3 located on an inner side of the column row 12 with respect to the end columns 20-1, 20-4, and the buffer means 50, which is also used as one or more other ropes 30, is attached to at least one folded end of each rope.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a protective fence for capturing falling rocks, collapsing earth and sand, etc. on a slope to prevent disasters, and particularly to a protective fence configured by suspending a plurality of ropes between columns.

Background Art

[0002] Conventionally, on slopes such as mountains, protective fences are installed to protect adjacent roads, railways and residences from natural disasters such as landslides, falling rocks, and avalanches. Particularly in Japan, where damage caused by earthquakes and heavy rains is frequent, it is important to install protective fences on slopes and other areas as a countermeasure against disasters.

[0003] A protective fence is generally configured by suspending a rope or net between a plurality of columns erected at intervals. In such a protective fence, when receiving an impact load by receiving a falling rock or the like, the impact is mitigated by the elongation of the rope or net.

[0004] In a protective fence using a rope, a structure is generally used in which both ends of the rope are locked to the columns at both ends of a column row in which a plurality of columns are erected, that is, the end columns, and the rope is suspended. Further, in order to enhance the impact absorption effect, a buffer device is provided at the end of the rope to absorb the impact force and mitigate the impact load acting on the rope when a tensile force of a predetermined value or more acts on the rope.

[0005] For example, Patent Document 1 describes a protective fence in which ropes wound in a loop shape are provided in multiple stages in the vertical direction of the columns between adjacent columns. In this protective fence, the rope is formed in a loop shape by overlapping near both ends of the rope and gripping with a buffer device. This buffer device allows the sliding of the rope when a tensile force of a predetermined value or more acts on the rope. Stoppers for stopping the sliding of the rope are provided at both ends of the rope.

[0006] In the protective fence described in Patent Document 1, when a falling rock strikes the rope and a tensile force exceeding a predetermined value acts on the rope, the rope slides against the gripping force of the buffer device, creating a frictional force between the rope and the buffer device, which absorbs the impact force from the falling rock. At the same time, a frictional force is also generated between the rope and the support post around which it is wrapped, absorbing the impact force, thus maintaining a high level of impact force absorption performance for each rope. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 3692457 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In protective fences equipped with shock absorbers, if a rockfall causes the rope to stretch and the shock absorber to activate, the shock absorber will need to be replaced during maintenance.

[0009] In the protective fence described in Patent Document 1, a buffer device is attached to each loop-shaped rope, resulting in a large number of buffer devices being installed. Consequently, there was a problem of increased installation and maintenance costs.

[0010] The present invention has been made in view of the above problems, and aims to provide a protective fence that captures falling rocks and the like using multiple ropes suspended between support posts, while achieving high impact absorption performance and reducing the costs and effort required during installation and maintenance. [Means for solving the problem]

[0011] To achieve the above objective, the protective fence described in claim 1 is: A row of support columns, in which multiple support columns are erected at predetermined intervals, Multiple ropes are suspended in multiple stages at predetermined intervals in the vertical direction from the aforementioned row of support columns, A protective fence comprising a buffering means attached to the rope, which increases the suspension length of the rope to absorb impact force when a tensile force exceeding a predetermined value is applied, Each rope has at least one end folded back at the end post located at the outermost end of the row of posts, and its tip is secured to a post located further inside the row of posts than the end post. The buffering means is configured such that at least two of the ropes arranged in upper and lower sections share one buffering means, At least one folded end of the rope Take It is characterized by being attached.

[0012] With this configuration, when a falling rock strikes the rope and a tensile force exceeding a predetermined value is applied to the rope, the impact force can be absorbed by the buffer attached to the end of the rope, and frictional force can be generated between the rope and the end support to absorb the impact force. Furthermore, when a falling rock strikes one rope and the buffer is activated, frictional force can also be generated between the other ropes sharing this buffer and the end support to absorb the impact force, thus achieving high impact absorption performance. Furthermore, by sharing one buffer mechanism with two or more ropes, the number of buffer mechanisms installed in the protective fence can be reduced, thereby lowering the costs and effort involved in the installation and maintenance of the protective fence.

[0013] Furthermore, the protective fence described in claim 2 is the protective fence described in claim 1, Each of the aforementioned ropes is suspended on the mountain-side surface of the column row, and both ends of each rope are folded back from the mountain side to the valley side at the end column located at the outermost end of the column row, with their ends secured to columns located further inside the column row than the end column.

[0014] In this configuration, a rockfall trapping surface is formed by each rope suspended on the uphill side of the support column row. Since the buffering means are attached to the ends of each rope positioned on the downhill side of the slope beyond this rockfall trapping surface, rocks are trapped on the rockfall trapping surface before they hit the buffering means. This prevents the buffering means from being damaged by rocks directly hitting them, allowing the buffering means to function properly and reducing maintenance costs due to damage to the buffering means. In addition, the protective fence can be made more space-efficient by keeping each rope within the range of the support column row.

[0015] Furthermore, the protective fence described in claim 3 is the protective fence described in claim 2, The installation of the buffering means and each rope is as follows: The tip of the uppermost rope is secured directly to the support post on either the left or right side of the row of support posts, or via the buffering means, and the end of the rope is secured to the support post on the opposite side via the buffering means. Each rope in the next row, from the second rope from the top, has its end connected to the end of the rope immediately preceding it, along with the aforementioned buffering means. for It is then secured to the support post, and its end is connected to the tip of the next rope and the buffering means. for And it is locked to the support column, The end of the lowest rope is characterized by being secured to the support post either directly or via the buffering means.

[0016] In this configuration, each rope from the second rope onwards is secured to the same support post at its tip via a common buffer mechanism shared with the rope above it, and at its end, it is secured to the same support post via a common buffer mechanism shared with the next rope. As a result, each of the multiple ropes suspended vertically forms a continuous structure with buffer mechanisms interposed as a whole. Therefore, when an impact is applied to the rope, the impact force is effectively dispersed, improving energy absorption performance.

[0017] Furthermore, the protective fence described in claim 4 is the protective fence described in any one of claims 1 to 3, The buffer means or the support column is equipped with a connecting device for connecting two ropes, The connecting tool is formed in a substantially triangular shape, and one end of each of the two ropes is connected to two of the three corners, and the remaining one is connected to the mounting portion of the buffer means or the support column.

[0018] According to this configuration, when one of the two rope materials connected to the two corners of the connecting tool receives a greater tensile force than the other rope material due to the impact force caused by a falling rock, the connecting tool rotates such that the remaining two corners rotate about the corner connected to the buffer means or the support column as a substantially center. As a result, a tensile force in a direction that suppresses the elongation of one rope material acts on the other rope material. Thus, by automatically adjusting the force so that the tensile forces acting on each of the two ropes become uniform via the connecting tool, the durability and energy absorption performance of each rope against the impact force can be improved.

[0019] Further, the protective fence according to claim 5 is the protective fence according to any one of claims 1 to 4, the buffer means is configured to be detachable from the rope, a deformation part that is connected to the rope and elongates in the length direction of the rope when receiving a tensile force of a predetermined value or more from the rope, and a friction resistance part that abuts against the deformation part and generates a frictional force when the deformation part elongates, and is characterized by including these.

[0020] According to this configuration, the deformation part of the buffer means absorbs the impact force transmitted from the rope by deforming when receiving the tensile force from the rope and generating a frictional force with the friction resistance part during deformation, and damage to the rope can be avoided by the operation of the buffer means. Further, during maintenance after the buffer means has operated, the buffer means can be removed from the rope, only the buffer means can be replaced, and the existing rope can be continuously used, so that the labor and cost of maintenance can be reduced.

[0021] The protective fence according to claim 6 is the protective fence according to any one of claims 1 to 5, The device is characterized by having an abrasion member attached to the outer surface of the end support so as to be interposed between the end support and the rope, and made of a material softer than the end support.

[0022] In this configuration, the rope is folded back at the end post, meaning a portion of the rope is wrapped around the end post. When a tensile force is applied to the rope due to a rockfall, the portion of the rope wrapped around the end post slides along the outer surface of the end post. At this time, the rope slides while generating frictional force with the wear member attached to the outer surface of the end post. This frictional force wears down the wear member, efficiently absorbing the impact energy. Furthermore, by using the wear member as an intermediary, damage to the post itself can be prevented, thus reducing the frequency of post replacement and lowering maintenance effort and costs. [Effects of the Invention]

[0023] According to the protective fence support structure of the present invention, when a falling rock strikes a rope and a tensile force exceeding a predetermined value acts on the rope, the impact force can be absorbed by the cushioning means attached to the rope, and the impact force can be absorbed by generating frictional force between the two or more ropes connected to the cushioning means and the end support post, thus achieving high impact absorption performance. Furthermore, since the number of cushioning means installed in the protective fence can be reduced, the costs and effort incurred during the installation and maintenance of the protective fence can be reduced. [Brief explanation of the drawing]

[0024] [Figure 1] This is a perspective view of a protective fence, which is the first embodiment of the present invention, as seen from the slope valley side. [Figure 2] This is a view of the protective fence from above. [Figure 3] This is a close-up view of the main part of the protective fence. [Figure 4] This is a cross-sectional view of the end support column, showing the mounting state of the wear member. [Figure 5A]This is a side view showing another embodiment of a wear member attached to the end support column. [Figure 5B] This is a cross-sectional view along line BB in Figure 5A. [Figure 6A] This is a side view of the shock absorber. [Figure 6B] This is a plan view of the shock absorber. [Figure 7] This is a perspective view showing another embodiment of the buffer device. [Figure 8] This is a perspective view showing another embodiment of the buffer device. [Figure 9] This is a close-up view of a key part, similar to Figure 3, which shows another embodiment of the protective fence. [Figure 10A] Figure 9 is an enlarged view of the connector shown. [Figure 10B] This is a diagram illustrating the operation of the connector. [Figure 11] This is a front view of the second embodiment of the protective fence, seen from the slope valley side. [Modes for carrying out the invention]

[0025] [First Embodiment] Figure 1 is a front view of the protective fence 10, which is the first embodiment of the present invention, as seen from the valley side of the slope, and Figure 2 is a view of the protective fence from above. Note that the drawings used in the description of the present invention are schematic diagrams, and the main parts of each component are exaggerated, and the dimensions of each component are not shown precisely. The protective fence 10 is installed on the construction ground G at the bottom of the slope and prevents damage by catching falling rocks and collapsing soil with multiple ropes 30-1 to 30-8 suspended from multiple support posts 20-1 to 20-4. Here, the construction ground G is a concept that includes the natural slope and embankment, and further includes the flat ground near the slope that has been formed for the installation of the protective fence 10. In the following description, the construction ground G will also be simply referred to as "ground G".

[0026] The protective fence 10 of this embodiment comprises a column row 12 consisting of a plurality of support posts 20-1 to 20-4, a plurality of ropes 30-1 to 30-8 suspended in multiple stages at predetermined intervals in the vertical direction from the column row 12, a buffer device 50 which is a buffering means attached to the ropes 30, a spacing member 60 which maintains the vertical spacing of each rope 30, and a net 70. The net 70 is optional, and in Figures 1 and 2, the net 70 is omitted in order to make the present invention easier to understand, while Figure 3 shows an example in which the net 70 is stretched over the protective fence 10.

[0027] Multiple support posts 20 are erected at predetermined intervals along the lateral (left-right) direction of the mountain slope, with one end embedded in the ground G, forming a single row of support posts 12. Preferably, the row of support posts 12 consists of four or more support posts 20 in order to secure both ends of the ropes 30 to the inner support posts 20-2, 20-3 of the row of support posts 12. Each rope 30 is suspended in a series from this row of support posts 21. Figure 1 shows a row of support posts 21 consisting of four support posts 20-1 to 20-4 as an example. In the following description, the two support posts 20-1 and 20-4 located at the very ends of the row of support posts 21 are also referred to as end posts, and the support posts 20-2 and 20-3 erected between the two end posts 20-1 and 20-4 are also referred to as intermediate posts.

[0028] Figure 4 is a cross-sectional view of the end support column 20-4. In this embodiment, each support column 20-1 to 20-4 comprises a steel pipe 22 with a circular cross-section, an H-shaped steel beam 21 inserted inside the steel pipe 22, and a plurality of rope holders 24 attached to the outer surface of the steel pipe 22 at vertical intervals. Furthermore, the end support columns 20-1 and 20-4 are equipped with wear members 26 on the outer surface of the steel pipe 22.

[0029] The H-shaped steel beam 21 has a plate-shaped web portion 21A and a pair of flange portions 21B and 21C provided at both ends of the web portion 21A, and both sides of each flange portion 21B and 21C are joined to the inner surface of the steel pipe 22 by welding. In each support column 20-1 to 20-4, the H-shaped steel beam 21 is positioned so that the flange portions 21B and 21C extend in the lateral direction (left-right direction) of the slope of the mountain within the steel pipe 22. In this embodiment, the steel pipe 22 and the H-shaped steel beam 21 are set to approximately the same length, and the entire length of the H-shaped steel beam 21 is inserted into the steel pipe 22. However, the H-shaped steel beam 21 may be longer than the steel pipe 22, and the lower part of the H-shaped steel beam 21 may extend below the steel pipe 22. Note that the support column 20 is not limited to this, and for example, it may be a hollow pipe made of resin or metal filled with a filler material such as concrete.

[0030] The holder 24 maintains the vertical spacing of each rope 30. The holder 24 can be formed, for example, by welding both ends of a U-shaped fitting to the steel pipe 22. By arranging multiple of these U-shaped holders 24 at predetermined intervals along the length of the support column 20 and inserting the ropes 30 through them, the spacing of multiple ropes 30 in the support column row 12 can be maintained. Note that the holder 24 is not limited to the illustrated example; for example, it may be a long plate with multiple holes formed at predetermined intervals along its length. In such a case, the long plate can be attached along the length of the steel pipe 22, and the ropes 30 can be passed through each hole in the long plate.

[0031] The abrasion member 26 is made of a material softer than the end posts 20-1, 20-4 and is attached to the outer surface of the end posts 20-1, 20-4 so as to be interposed between the end posts 20-1, 20-4 and each rope 30. The abrasion member 26 can be made of a hard urethane resin, hard rubber, or other resin material that is softer than the steel pipe 22, which is the main body of the support column, and has a predetermined hardness, or a metal material that is softer than steel, such as aluminum. This abrasion member 26 is provided in at least the area around which the rope 30 is wrapped, and in this embodiment, it is formed in a layer that covers the entire outer surface of the steel pipe 22. For example, when the abrasion member 26 is made of hard urethane resin, it can be formed by applying a hard urethane resin coating to the outer surface of the steel pipe 22 to a predetermined thickness.

[0032] The wear member 26 absorbs impact energy by wearing down due to the frictional force of the rope 30 when the rope 30 slides on the outer surface of the end posts 20-1 and 20-4 under the tensile force of falling rocks, while preventing damage to the end posts 20-1 and 20-4. Preferably, the wear member 26 is made of a material with a higher coefficient of friction than the steel pipe 22 which is the main body of the post, so that the mechanical load on the post body is reduced by the energy absorption performance due to friction.

[0033] Figures 5A and 5B show another embodiment of the wear member 26. The wear member 26 in this embodiment has a different shape from the wear member 26 shown in Figure 4. It is formed as a tubular body bent in a roughly U-shape along the outer circumference of the steel pipe 22, with both ends of the U-shape facing inward in the lateral direction of the column row 12, and the rope 30 is inserted through the inside of this tubular body. In this way, when the rope 30 is inserted through the inside of the wear member 26, the wear member 26 can also be used as a holder for the rope 30, and the holder 24 shown in Figure 4 can be omitted.

[0034] As shown in Figures 1 and 2, the outer surfaces of the intermediate support posts 20-2 and 20-3 are provided with locking portions 25 for securing the ends of the rope 30. In this embodiment, the locking portion 25 is formed by a U-shaped metal fitting, with both ends welded to the outer surfaces of the customs clearance support posts 20-2 and 20-3.

[0035] The height of each support post 20 from the ground G can be, for example, 2m to 5m, the depth of each support post 20 in the ground can be, for example, 1m to 4m, and the spacing between the support posts 20 can be, for example, 2m to 10m. These can be appropriately selected depending on the size and condition of the slope.

[0036] As shown in Figure 1, in this embodiment, optional spacing members 60-1 to 60-3 are installed between each support column 20. Each spacing member 60 is a rod-shaped member that is long in the vertical direction and has rope-holding holes 62 through which each rope 30 is inserted at predetermined intervals along its length. In the illustrated example, a plurality of U-shaped fittings are welded at predetermined intervals to the outer surface of a rectangular tube with a square cross-section, and the ropes 30 are inserted through the rope-holding holes 62 formed by these U-shaped fittings. It is desirable that the rigidity of the spacing member 60 be greater than that of the rope 30 and less than that of the support column 20. In the illustrated example, the lower end of the spacing member 60 is fixed to the ground G using a base 66, but this is not limited to this, and the lower end of the spacing member 60 may be floating away from the ground G. This spacing member 60 is optional, and the number of spacing members 60 placed between adjacent support columns 20 can be set as appropriate.

[0037] Multiple ropes 30 are arranged in multiple rows on the column row 21 at predetermined intervals in the vertical direction. At least one end 30a and / or 30b of each rope 30 is folded back at the end column 20-1 or 20-4, and the tip of the rope is secured to the inner columns 20-2 and / or 20-3 of the column row 12. In addition, a buffer device 50, which is also used for one or more other ropes 30, is attached to at least one folded end 30a and / or 30b of each rope 30, and the tip is secured to the inner columns 20-2 and / or 20-3 via this buffer device 50. In this embodiment, as shown in Figures 1 and 2, each rope 30 is suspended on the slope-side face of the column row 12, and both ends 30a and 30b of each rope 30 are folded back from the slope side to the valley side at the end columns 20-1 and 20-4, and their ends are locked to the locking parts 25 of the intermediate columns 20-2 and 20-3 adjacent to the end columns 20-1 and 20-4 using locking fittings 38. Note that Figure 2 shows the suspension state of the uppermost rope 30-1 connected to the buffer device 50-1, and the lower rope 30-2 is not shown. In the illustrated example, the protective fence 10 is viewed from the slope-side, with the left end of the rope 30 being end 30a and the right end being end 30b. As shown in Figures 1 and 2, one end 30a or 30b of the rope 30 that is folded back is locked to the locking part 25 via the buffer device 50. Furthermore, if only one end 30a or 30b of the rope 30 is folded back and secured to the intermediate support posts 20-2 and 20-3, the other end 30b or 30a can be secured to the end support post 20-1 or 20-4.

[0038] As the rope 30, for example, a high-strength wire rope formed by twisting together wires manufactured from hard steel wire rods as specified in JIS G 3506 can be used. Wires made from hard steel wire rods are less susceptible to plastic deformation and have high tensile strength and springiness compared to wires made from mild steel wire rods as specified in JIS G 3505. The wire diameter of the rope 30 can be, for example, about 10 to 25 mm, preferably 18 mm or more, and the tensile strength of the rope 30 can be, for example, 500 to 2000 N / mm 2This can be done. Each rope 30 is suspended from the column row 21 and is inserted through the holder 24 of the column 20 and the rope holding hole 62 of the spacing member 60, thereby maintaining vertical spacing and extending almost parallel in the left-right direction (lateral direction). The vertical spacing of each rope 30 is, for example, 100 mm to 300 mm, and can be 200 mm to 400 mm when a net 70 is stretched as in this embodiment.

[0039] The net 70 is formed by weaving together metal wires. The net 70 is installed over the entire area where the rope 30 is suspended, and in this embodiment, it is positioned on the slope side of the rope 30. The upper and lower edges of the net 70 are connected to the uppermost and lowermost ropes 30 using wires. In the example shown in Figure 3, the mesh of the net 70 is formed in a diamond shape, but other mesh shapes such as circles may also be used. The wires forming the net 70 can be made of mild steel, hard steel, spring steel, stainless steel, etc., and it is also possible to use wires made from hard steel wire rods as specified in JIS G 3506. The diameter of the wires constituting the net 70 is smaller than the diameter of the rope 30. The wires forming the net 70 are not limited to metal; for example, wires made of carbon fiber, glass fiber, or aramid fiber, or resin wires with high corrosion resistance can be used. Furthermore, a geogrid may be used as the net 70. As in this embodiment, by installing the net 70 together with the rope 30, even if a rock falls on one of the ropes 30, a tensile force can be applied to the other ropes 30 via the net 70.

[0040] As shown in Figure 1, in this embodiment, auxiliary ropes 68 without a buffer device 50 are suspended in the area below the rockfall capture surface, which consists of multiple ropes 30. The net 70 extends to the suspension area of ​​these auxiliary ropes 68. Note that the protective fence 10 may be composed entirely of ropes 30 without using the auxiliary ropes 68.

[0041] The shock absorber 50 is attached to the folded end 30a or 30b of the rope 30, and absorbs the impact force by increasing the suspension length of the rope 30 when a tensile force exceeding a predetermined value is applied from the rope 30. One shock absorber 50 is attached to at least two ends of the rope 30. In this embodiment, an example is shown in which one shock absorber 50 is attached to two ropes 30, but for example, a structure in which one shock absorber 50 is attached to the ends of three folded ropes 30 may also be used. Figures 6A and 6B are a side view and a top view showing the shock absorber 50-1 and the ropes 30-1 and 30-2 connected thereto. The shock absorber 50 is configured to be detachable from the rope 30 and comprises a deformable part 54 that is connected to the rope 30 via a connecting fitting 57 such as a shackle, a friction resistance part 52 that abuts against the deformable part 54, and a housing part 51 to which the friction resistance part 52 is attached.

[0042] The housing portion 51 is formed in a roughly rectangular hollow cylindrical or box shape, with a cylindrical friction resistance portion 52 passing through its interior in the radial direction. A locking fitting 38 for locking the shock absorber 50 to a locking portion 25 of the support column 20 is attached to the end of the housing portion 51. The deformable portion 54 is formed of a metal strip member and is wrapped around the circumferential surface of the cylindrical friction resistance portion 52 and bent into a U shape. The housing portion 51 surrounds the U-shaped curved portion of this deformable portion 54. The ends of two ropes 30-1 and 30-2 are connected to one end 54a of the deformable portion 54 (the end that is shorter from the friction resistance portion 52) via a connecting fitting 57. A stopper 55 is provided at the other end 54b of the deformable portion 54 (the end that is longer from the friction resistance portion 52).

[0043] In this buffer device 50, when the deformable portion 54 receives a tensile force from the ropes 30-1 and 30-2 exceeding a predetermined value, it stretches in the longitudinal direction of the ropes 30-1 and 30-2, and the friction resistance portion 52 generates a frictional force when the deformable portion 54 stretches. Specifically, when a tensile force acts on the rope 30 and the rope 30 is pulled in the direction of arrow F in Figure 6A, one end 54a of the deformable portion 54 is also pulled in the same direction. As a result, the deformable portion 54 moves between the housing portion 51 and the friction resistance portion 52, and consequently, the curved portion of the deformable portion 54 wrapped around the friction resistance portion 52 moves towards the other end 54b where the stopper 55 is provided, causing continuous plastic deformation to occur in the deformable portion 54. This deformation of the deformable portion 54 generates a resistance force against the tensile force of the rope 30, creating a braking effect on the rope 30, i.e., a braking force, which greatly absorbs the kinetic energy when hit by falling rocks. The elongation of the rope 30 is restricted at the position where the stopper 55 contacts the friction resistance portion 52 and the housing portion 51, stopping the tension on the deformable portion 54. The deformable portion 54 in this embodiment is formed to have a constant thickness and width in the longitudinal direction, and can provide a substantially constant braking force when in operation.

[0044] As shown in Figure 1, one buffer device 50 is provided for each set of two adjacent ropes 30, and the buffer devices 50 arranged in upper and lower rows on the protective fence 10 are alternately placed at the left and right ends 30a and 30b of each set of ropes 30. That is, the buffer devices 50-1 and 50-3 for odd-numbered rows (2n-1 rows, where n is a natural number) are provided at the right end 30b (or left end 30a) of the set of two ropes, and the buffer devices 50-2 and 50-4 for even-numbered rows (2n rows, where n is a natural number) are provided at the left end 30a (or right end 30b) of the set of two ropes.

[0045] In the protective fence 10 described above, when a falling rock strikes the rope 30 and a tensile force exceeding a predetermined value acts on the rope 30, the impact force can be absorbed not only by the impact force absorption performance of the rope 30 itself through plastic deformation and elastic deformation, but also by the shock absorber 50 attached to the end of the rope 30. Furthermore, the impact force can be absorbed by generating frictional force between the rope 30 and the end posts 20-1, 20-4. In addition, if a falling rock strikes one of two ropes 30, for example, ropes 30-2 to which the same shock absorber 50 is attached, and the shock absorber 50-1 is activated, the impact force can also be absorbed by generating frictional force between the other rope 50-1 connected to the shock absorber 50-1 and the end post 20-4. This makes it possible to obtain high impact absorption performance.

[0046] Furthermore, in the aforementioned protective fence 10, since one buffer device 50 is attached to every two ropes 30, the number of buffer devices 50 installed in the protective fence 10 can be reduced. This reduces the costs and effort involved in the installation and maintenance of the protective fence 10.

[0047] In order to effectively activate the buffer device 50 via the rope 30 during a rockfall, it is preferable to keep the distance from the point on the rope 30 struck by the rock to the buffer device 50 within a predetermined range, so that the buffer device 50 is activated before the rope 30 is fully stretched. Therefore, it is preferable to attach at least one buffer device 50 to each of the upper and lower sections of the rope 30. In this embodiment, since two ropes share one buffer device 50, it is possible to effectively activate the buffer devices 50 connected to each rope 30 while reducing the number of buffer devices 50 to be installed.

[0048] Furthermore, the shock absorber 50 of this embodiment is configured to be separable from the rope 30. The deformable part 54 deforms when it receives tensile force from the rope 30, generating frictional force with the friction resistance part 52, thereby absorbing the impact force transmitted from the rope 30. This structure prevents damage to the rope 30 due to the operation of the shock absorber 50. In addition, during maintenance after the shock absorber 50 has been activated, the shock absorber can be removed from the rope 30, and only the shock absorber 50 can be replaced, allowing the existing rope 30 to be used continuously. This reduces the effort and cost of maintenance.

[0049] Furthermore, in the protective fence 10 of this embodiment, when a tensile force acts on the rope 30 due to a falling rock, and the rope 30 slides on the outer surface of the end posts 20-1, 20-4, the rope 30 slides on the wear member 26, which prevents damage to the steel pipe 22 that forms the main body of the post, while efficiently absorbing impact energy with a large frictional force. If the steel pipe 22 is damaged, it is necessary to replace the entire post 20 and drive it into the ground G again, which is time-consuming and costly, but in the protective fence 10 of this embodiment, it is also possible to replace only the damaged wear member 26. In this way, the protective fence 10 of this embodiment can reduce the frequency of replacement of the post 20 while improving impact force absorption performance, thereby reducing the time and cost of maintenance.

[0050] Furthermore, in the protective fence 10 described above, both ends of each rope 30 are folded back at end posts 20-1 and 20-4 and secured to posts 20-2 and 20-3 which are located inside the end posts 20-1 and 20-4. This allows each rope 30 to be housed within the row of posts 12, thus reducing the installation space. In addition, each rope 30 is suspended on the slope-side face of the row of posts 12, and the buffer device 50 is attached to the ends of the ropes 30 that are folded back from the slope-side to the valley-side at end posts 20-1 and 20-4. This prevents rockfalls from directly hitting the buffer device 50, thus preventing damage to the buffer device 50. In this embodiment, since the net 70 is stretched on the slope-side of the buffer device 50, the structure is designed to make it even more difficult for rockfalls to hit the buffer device 50.

[0051] The buffer device 50 is not limited to the one described above. For example, it may be integrated with the rope 30, as shown in Figure 7. The buffer device 50 shown in Figure 7 is made of a metal fastening member 58 having holes 58a through which four ropes 30 can be inserted. For example, a compression sleeve can be used for the fastening member 58. In this buffer device 50, two ropes 30-1 and 30-2 are inserted, each rope 30 is wound once in a ring shape, and then the ropes 30-1 and 30-2 are inserted again through the holes 58a from the same direction, and the fastening member 58 is crimped to fix the two inserted ropes 30-1 and 30-2 in place. In this shock absorber 50, when rope 30-1 and / or rope 30-2 are pulled, ropes 30-1 and 30-2 come into frictional contact with each other within the hole 58a of the fastening member 58, and each rope 30-1 and 30-2 also comes into frictional contact with the fastening member 58, thereby absorbing the impact force.

[0052] Figure 8 shows yet another embodiment of the shock absorber 50. This shock absorber 50 is configured to be separable from the rope 30 and comprises two tubular bodies 59A and 59B formed in a loop shape, which are deformable parts, and a tightening member 58 that grips both ends of the tubular bodies 59A and 59B to maintain the loop shape. The tightening member 58 constitutes a friction resistance part that generates frictional force between itself and the tubular bodies 59A and 59B. The tubular bodies 59A and 59B are preferably made of steel, but may be made of other metal materials or resin materials. Ropes 30-1 and 30-2 are inserted through the two tubular bodies 59A and 59B, respectively. Both ends of each tubular body 59A and 59B are superimposed in parallel within the hole 58a of the tightening member 58, and this superimposed part is tightened by the tightening member 58. In this shock absorber 50, when the rope 30-1 and / or rope 30-2 are pulled, the tubular bodies 59A and 59B come into frictional contact with each other within the hole 58a of the tightening member 58, and each tubular body 59A and 59B also comes into frictional contact with the tightening member 58, thereby absorbing the impact force. This shock absorber 50 prevents damage to the rope 30 when the shock absorber 50 is activated.

[0053] In the buffer device 50 shown in Figures 7 and 8, the annular portion of the buffer device 50 shrinks in diameter, and the rope 30 shifts towards the center of the protective fence 10 due to the reduction in diameter, thereby increasing the resistance to falling rocks. The size of the annular portion can be changed as appropriate to obtain the desired buffering effect; if a larger buffering effect is required, the annular portion can be made larger. The buffer device 50 in Figures 7 and 8 can be made simpler and less expensive than the buffer device 50 shown in Figure 6A.

[0054] Figure 9 shows another embodiment of the protective fence 10. This protective fence 10 is equipped with a connector 80 for connecting two ropes 30 to a buffer device 50 or a support post 20. Figure 10A is an enlarged view of the connector 80. The connector 80 comprises a main body 82 formed in the shape of a roughly triangular plate, and a first connecting fitting 84, a second connecting fitting 85, and a third connecting fitting 86 provided at the three corners of the main body 82. One end of the two ropes 30 is connected to two of the three corners of the connector 80, and the remaining end is connected to the mounting part of the buffer device 50 or the support post 20. The main body 82 is preferably in the shape of a roughly equilateral triangle, or a roughly isosceles triangle with the corner of the first connecting fitting 84 as the vertex angle. Figure 10A shows an example in which one end of two ropes 30-1 and 30-2 (the tip of the right end 30b of ropes 30-1 and 30-2) is connected to two connecting fittings 85 and 86 of the connector 80, and a connecting fitting 57 (the mounting part of the shock absorber 50) attached to one end of the deformed part 54 of the shock absorber 50 is connected to the remaining connecting fitting 84.

[0055] Figure 10B is a diagram illustrating the operation of the connector 80. When the connector 80 is subjected to an impact force from a falling rock, and a greater tensile force F acts on one of the two ropes connected to it, for example, ropes 30-1 and 30-2, than on the other rope, the second rope 30-1, the connector 80 rotates counterclockwise from the initial position shown in Figure 10A to the rotational position shown in Figure 10B, with the corner to which the buffer device 50 is connected (i.e., the corner to which the first connecting fitting 84 is attached) as the approximate center. When this rotational movement occurs, a force f1 acting on the second connecting fitting 85 to suppress the rotational movement is exerted by the second rope 30-1, and consequently, a force f2 acting on the third connecting fitting 86 to resist the tensile force F of the first rope 30-2. In this way, by automatically adjusting the force so that the tensile force acting on each of the two ropes 30-1 and 30-2 is uniform via the connector 80, the durability and energy absorption performance of each rope 30-1 and 30-2 against impact forces can be improved.

[0056] Although not shown in the diagram, the left end 30a of the first rope 30-2 and the left end of the second rope 30-2 (the end to which the shock absorber 50 is not attached) are connected and locked to the locking part 25 of the intermediate support column 20-2 via the connector 80. A locking fitting 38 can be used between the connector 80 and the locking part 25 as needed. Figure 9 shows an example in which the right end 30b of the two ropes 30-3 and 30-4 are connected to the intermediate support column 20-3 via the connector 80 and the locking fitting 38. In this way, even at the end to which the shock absorber 50 is not attached, by locking it to the support column 20 via the connector 80, it is possible to obtain the effect of automatically adjusting the force acting on the two ropes so that it is uniform when an impact force from falling rocks is applied by the connector 80. In this way, even at the end where the buffer device 50 is not attached, by securing it to the support column via the connector 80, it is possible to obtain the effect of automatically adjusting the force acting on the two ropes 30 so that it is uniform when an impact force from falling rocks is applied by the connector 80.

[0057] [Second Embodiment] Figure 11 is a front view of the second embodiment of the protective fence, as seen from the slope valley side. In Figure 11, the same reference numerals are used for parts corresponding to those in the first embodiment. In the second embodiment described below, detailed explanations of configurations similar to those in the first embodiment will be omitted.

[0058] In the second embodiment, a set of two ropes 30, one above the other, is attached to a single buffer device 50. The arrangement of the buffer device 50 and each rope 30 is such that the tip of the uppermost rope 30-1 is secured to either the left or right support column 20-2 or 20-3 of the column row 12, either directly or via the buffer device 50, and the end of this rope 30-1 is secured to the opposite support column 20-3 or 20-2 via the buffer device 50. Furthermore, each rope 30 from the second to the top in the next row is sequentially secured to the support column 20-2 or 20-3, sharing the buffer device 50 with the end of the rope above it, and its end is secured to the support column 20-3 or 20-2, sharing the buffer device 50 with the end of the next rope. The end of the lowest rope 30-10 is secured to the support column 20-2 or 20-3, either directly or via the buffer device 50.

[0059] In the example shown in Figure 11, the tip of the top rope 30-1 is directly secured to the left support post 20-2 of the support post row 12, and the end of rope 30-1 is secured to the right support post 20-3 of the support post row 12 via a buffer device 50-1. The second rope from the top, 30-2, has its tip secured to the intermediate support post 20-3, sharing a buffer device 50-1 with the end of the upper rope 30-1, and its end is secured to the support post 20-2, sharing a buffer device 50-2 with the end of the next rope 30-3. In this manner, the ropes 30 from the second rope onwards are sequentially secured to the left or right intermediate support column 20-2 or 20-3 of the column row 12, sharing a buffer device 50 with the end of the rope 30 above, and their ends are secured to the opposite intermediate support column 20-3 or 20-2, sharing a buffer device 50 with the end of the next rope 30. The end of the lowest rope 30-10 is directly secured to the intermediate support column 20-2.

[0060] In this embodiment, each rope 30 from the second rope onwards is secured to the same support column at its tip via a common buffer device 50 shared with the upper rope 30, and at its end, it is secured to the same support column 20 via a common buffer device 50 shared with the next rope 30. As a result, each of the multiple ropes 30 suspended vertically forms a continuous structure with the buffer device 50 interposed as a whole. Therefore, when an impact is applied to the rope 30, the impact force is effectively dispersed, improving energy absorption performance.

[0061] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0062] For example, each rope 30 may be suspended on the valley-side face of the column row 12, with both ends of each rope 30 folded back towards the slope side at end columns 20-1, 20-4, and its tip secured to an anchor driven into the ground G. Alternatively, one end of the rope 30 may be fixed to one end column 20-1 or 20-4, the other end folded back at the other end column 20-4 or 20-1, and the folded tip fixed to the ground G using an anchor. In this case as well, the buffer device 50 is attached to the folded end of the rope 30, and one is attached to at least two ends of the ropes, similar to the first or second embodiment. [Explanation of Symbols]

[0063] 10 Protective fence 12 column rows 20 pillars 20-1,20-4 End strut 26 Abrasion member 30 ropes 50 Shock absorber 52 Friction resistance part 54 Deformed part 60 Spacing member 70 Net 80 Connectors G ground

Claims

1. A row of support columns, in which multiple support columns are erected at predetermined intervals, Multiple ropes are suspended in multiple stages at predetermined intervals in the vertical direction from the aforementioned row of support columns, A protective fence comprising a buffering means attached to the rope, which increases the suspension length of the rope to absorb impact force when a tensile force exceeding a predetermined value is applied, Each rope has at least one end folded back at the end post located at the outermost end of the row of posts, and its tip is secured to a post located further inside the row of posts than the end post. The buffering means is attached to at least one folded end of the rope, in such a manner that at least two of the ropes arranged in upper and lower sections share one buffering means.

2. The protective fence according to claim 1, characterized in that each of the ropes is suspended on the slope-side face of the row of posts, and both ends of each rope are folded back from the mountain side to the valley side at the end post located at the outermost end of the row of posts, with the ends being secured to posts located inside the row of posts rather than the end post.

3. The installation of the buffering means and each rope is as follows: The tip of the uppermost rope is secured directly to the support post on either the left or right side of the row of support posts, or via the buffering means, and the end of the rope is secured to the support post on the opposite side via the buffering means. Each rope from the second rope from the top of the next row is sequentially secured to the support post by sharing the buffering means with the end of the rope of the previous row, and the end of each rope is secured to the support post by sharing the buffering means with the end of the rope of the next row. The protective fence according to claim 2, characterized in that the end of the lowest rope is secured to the support post directly or via the buffering means.

4. The buffer means or the support column is equipped with a connecting device for connecting two ropes, The protective fence according to any one of claims 1 to 3, characterized in that the connector is formed in a substantially triangular shape, with one end of each of the two ropes connected to two of the three corners, and the remaining one connected to the buffering means or the mounting part of the support post.

5. The buffering means is configured to be detachable from the rope. A deformable portion connected to the aforementioned rope that extends in the longitudinal direction of the rope when subjected to a tensile force exceeding a predetermined value from the rope, A protective fence according to any one of claims 1 to 4, further comprising a friction resistance portion that contacts the deformed portion and generates a frictional force when the deformed portion is extended.

6. The protective fence according to any one of claims 1 to 5, characterized in that it includes an abrasion member attached to the outer surface of the end post so as to be interposed between the end post and the rope, and made of a material softer than the end post.

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