JP5054742B2 - Rock fall protection fence - Google Patents

Description

The present invention relates to a rockfall protection fence of a type installed along a road or the like to absorb impact forces such as rockfalls and avalanches with cable elongation.

As a means to protect roads and houses from falling rocks that occur in the slopes of mountainous areas, several horizontal horizontal ropes are stretched between the columns at intervals, and a wire mesh is attached to the surface of the stretched horizontal rope. A rockfall guard fence is attached to catch rockfalls.
In such a rockfall protection fence, a looped ring is formed in the middle of a single rope, and the overlapping part is clamped with a clamping tool. When tension is applied to the rope, the extra length of the looped part has a constant frictional force. A rope constructed so that it slides frictionally with each other while holding it is stretched between struts, and shock energy is attenuated and absorbed by frictional sliding of the extra length overlapped when a falling rock falling from the mountain side hits the rope directly A rock fall protection fence has been proposed. (Patent Document 1)

In addition, a load transmission body having a three-dimensional shell structure is used, and the impact tensile load applied to the load transmission body is converted into a compression load. It is proposed that a shock-absorbing metal fitting that absorbs an impact load is connected to a rope and used for a protective net or the like. (Patent Document 2)

Japanese Patent Publication No. 7-18134 JP 2004-169336 A

The shock absorbing fence of Patent Document 1 is a method of absorbing collision energy by frictional resistance due to frictional sliding, and since the frictional resistance depends on the rope tightening force of the clamp, ensuring a uniform and stable resistance value There is a problem that is difficult.
Further, the collision energy absorption method using the buffer metal fittings of Patent Document 2 differs in the parts that plastically deform the buffer metal parts depending on the strength of the load. Therefore, the parts are plastically deformed (destructed) even under a light load. There is a problem that requires repair or replacement.

The present invention was devised in order to solve the above-mentioned problems, and the object of the present invention is compact and high in efficiency of absorbing rockfall energy, in terms of strength, function, construction, and repair. The object is to provide a rockfall protection fence that performs excellent functions.

In order to achieve the above-mentioned object, the present invention is provided with a terminal column standing at an interval along a portion where rock fall, avalanche, etc. on an inclined surface should be prevented, and an interval between the terminal columns. In a rockfall protection fence comprising a plurality of intermediate struts, a cable stretched in multiple steps at intervals along the mountain side of the terminal struts and the intermediate struts, and a wire mesh stretched on the cable surface, the cable The rock receiving rope and a buffer rope having a longitudinal elastic modulus smaller than the rock receiving rope and connected to both ends of the rock receiving rope. (Claim 1)

According to the present invention, each cable stretched between terminal struts having a predetermined interval has a rock receiving rope having a relatively large longitudinal elastic modulus A and a longitudinal elastic modulus B smaller than this, It is composed of buffer ropes connected to both ends of the rope, and a rock catching rope with high elastic properties is arranged in the central part of the fence where rockfalls occur frequently. By placing a buffer rope with low elastic properties in the vicinity of almost no end struts, it is possible to cover the weak points that are easily damaged by falling stones, and to fully draw out the characteristics excellent in impact energy absorption. Therefore, since the amount of impact energy absorbed is high, the impact load on the terminal column can be greatly reduced, and the terminal column can be downsized.
In addition, there is little variation in characteristic values such as strength and elongation, and rockfall energy can be stably distributed to each of the cable, the wire mesh, and the terminal support.
Furthermore, in the case of minor rockfalls, if the rockfalls are removed, the cable stretches back to the initial value and no repair is required, so maintenance is easy.

It is a perspective view which shows 1st Example of the rock fall protection fence by this invention. (A) is a partial front view of the rock fall protection fence by this invention, (b) is a top view, (c) is a side view. (A) is a front view which shows the coupling | bonding relationship with the connection of a buffer rope and a rock receiving rope of this invention, and a terminal support | pillar, (b) is a top view. (A) is a front view of the space | interval holding | maintenance material part in this invention, (b) is a side view. (A) is a schematic diagram which shows the state before the falling rock in the falling rock protection fence of this invention, (b) is a schematic diagram which shows the energy absorption state at the time of falling rock. It is explanatory drawing which shows the dynamic tension test of the rope used by this invention.

Preferably, the elongation P1 of the buffer rope is in the range of 20% ≦ P1 ≦ 65%, and the elongation P2 of the rock receiving rope is in the range of 4% ≦ P2 ≦ 6%.
According to this, the energy absorption amount of the buffer rope can be increased to 5 to 10 kJ than the energy absorption amount of the rock receiving rope, the energy absorption due to the plastic deformation of the entire cable is increased, and the cable absorbs much of the impact energy efficiently. Since the energy applied to the terminal fittings, terminal struts, and intermediate struts is attenuated, these fittings and members can be miniaturized.

Preferably, a plurality of upper and lower stages of cables and a metal mesh are coupled with a spacing member, and the upper and lower stages of cables and the metal mesh are integrated.
According to this, even when the rock falls directly hit one cable, the rock retaining energy is transmitted to the entire wire mesh and the upper and lower cables by the spacing member, so that the efficiency of absorbing the rock falling energy is further enhanced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an embodiment of a rockfall protection fence according to the present invention, where a is a mountain side and b is a road side. Reference numeral 1 denotes a high energy absorption type rock fall protection fence of the present invention installed along the boundary between the road and the mountain side inclined surface.
In the rock fall protection fence 1, the terminal struts 2 and 2 are erected on the left and right sides, a plurality of intermediate struts 3 are erected between the terminal struts 2 and 2 at equal intervals, and the plurality of cables 4 are vertically moved. The end portions are fixed to the terminal columns 2 and 2, respectively.
The tensioned cable 4 is slidably attached to each intermediate column 3. Further, a wire mesh 7 is stretched over the entire mountain side along a plurality of cables 4 stretched between the terminal columns 2 and 2, and the cable 4 and the wire mesh 7 are fixed by a spacing member 8.

The terminal struts 2 and 2 are made of, for example, H-shaped steel having a length of 175 mm × 175 mm × 7.5 mm × 11 mm and a length of 2,850 mm, and are galvanized in order to enhance the anticorrosion effect. However, the terminal column may be a square column or a square steel pipe, or may be resin-coated on galvanized.
The terminal columns 2 and 2 are arranged at intervals along the road, and are erected by embedding lower portions 201 and 201 having a required length, for example, 850 mm, in cement-based foundations 60 and 60 such as mortar and concrete. .
However, the present invention is not limited to this, and a plate metal fitting with a stay may be provided at the lower portion, and the metal plate may be erected by being rigidly connected to a metal plate (not shown) anchored to a cement-based foundation.

The intermediate strut 3 is made of, for example, an H-shaped steel having a length of 200 mm × 100 mm × 5.5 mm × 8 mm and a length of 2,850 mm, and is galvanized to enhance the anticorrosion effect. Furthermore, resin coating may be applied to enhance the landscape.
The intermediate strut 3 is disposed with a space between the terminal struts, and is erected by embedding a lower portion 301 having a required length, for example, 850 mm, in a cement base 60 such as mortar or concrete.
However, the present invention is not limited to this, and a plate metal fitting with a stay may be provided at the lower portion, and the metal plate may be erected by being rigidly connected to a metal plate (not shown) anchored to a cement-based foundation.

  A feature of the present invention is that the cable 4 stretched between the terminal struts 2 and 2 has two types of ropes 5 and 6 whose longitudinal elastic modulus A and B satisfy the formula of A> B, and has a large elastic modulus. The rope 6 is arranged in a region including the center for the main body of the fence, and the rope 5 having a small elastic coefficient is connected to both ends of the rope to constitute one cable having a large impact energy absorption.

The rope 6 having a relatively large longitudinal elastic modulus A is a rock receiving rope, and the rope 5 having a relatively small longitudinal elastic modulus B is a buffer rope.
Here, the elastic modulus A is desirably 120,000 to 80,000 N / mm ² . The reason is that when it is 120,000 N / mm ² or more, it becomes hard and energy absorption cannot be expected, and when it is 80,000 N / mm ² or less, it is easy to be scratched by falling rocks and shear fracture is likely to occur.
The elastic modulus B is preferably 60,000 to 40,000 N / mm ² . The reason is that when it is 60,000 N / mm ² or more, it becomes hard and sufficient energy absorption cannot be expected, and when it is 40,000 N / mm ² or less, sufficient breaking strength cannot be obtained.

The buffer rope 5 is, for example, a soft stainless steel wire (components are C: 0.001% to 0.15%, Si: 0.01% to 1.5%, Mn: 0.3% to 3.0%, P : 80.05% or less, S : 80.02% or less) Cr: 14.0% to 26.0%, Ni : 86.0% to 22.0%, N: 0.02% or less, and substantially the remainder Fe), and the rock receiving rope 6 is made of, for example, a hard wire specified in JIS G 3521. Steel wire is used.

More preferably, the buffer rope 5 is a rope having a large absorption energy with an elongation P1 of 20% ≦ P1 ≦ 65%. The reason why the lower limit of elongation is set to 20% is that if it is less than this, energy absorption is small and a sufficient effect cannot be obtained. The upper limit is set to 65%. This is because falling rocks protrude. Preferably, it is desirable to keep the upper limit to about 55% so that the falling rocks do not hinder the traffic of large vehicles.

The rock receiving rope 6 has an elongation P2 of 3% ≦ P2 ≦ 6%. The lower limit is 3% because energy absorption is less when it is less than this, and the upper limit is 6% because when the rock hits the rope, the rope is easily scratched. The elongation can be achieved by controlling the twist pitch. Furthermore, it is possible to control the heat treatment of the wire.

As a specific example of the cable 4, the rock receiving rope 6 is a 3 × 7, 18 mm diameter, galvanized wire rope having a twist pitch of 150 mm and an elongation of 5%. The buffer ropes 5 and 5 are made of soft stainless steel, and the twist pitch is 126 mm and the elongation is 52%.

FIG. 3 shows the cable 4 attached to the terminal strut 2. The buffer rope 5 has an open socket 52 attached to the end as a metal fitting for fastening to the terminal strut 2, and the rock receiving rope 6 on the other end. A fork end 53 is attached as a metal fitting for connection.
The buffer rope 5 preferably has a length of 1800 to 3000 mm. This is because if the length is short, sufficient energy absorption cannot be obtained, and if it exceeds 3000 mm, the possibility of being directly hit by a falling rock increases.
The end fittings are not limited to this, and a screw end, an eye end, a toyo lock and the like can be selected.

A thimble 62 is attached to the end of the rock receiving rope 6 by a clip 61 fastening. A fork end 53 of the buffer rope 5 and a thimble 62 of the rock receiving rope 6 are connected via a bolt and nut 63. The open socket 52 attached to the end of the buffer rope 5 is fastened to the terminal column 2 via the cable end fitting 54.
The cable end fitting 54 is composed of a rod with male threads cut at both ends, one end is fixed to the open socket 52 with a nut 541, and the other is inserted into a cable end fitting insertion hole 543 provided in the terminal support column 2. The cable 4 is fixed with a certain tension.

As shown in FIG. 1 and FIG. 2, the multi-stage cable 4 is stretched on the terminal struts 2 and 2 in parallel at equal intervals in the vertical direction, but is not fixed to the intermediate strut 3 and is not fixed by U bolts 31 and 31. It is slidably attached in the axial direction. The advantage of being slidable is that when the cable 4 is tensioned by falling rocks, the cable becomes thin, the binding force of the U bolts 31 and 31 is weakened, the entire cable is propagated, and the impact energy absorption efficiency is increased. Because.

For example, a 50 mm × 50 mm rhombus wire mesh 7 is arranged on the entire mountain side of the terminal columns 2, 2 and the intermediate column 3, and is attached to the cable 4 with a coupling coil (not shown). In the multistage cable 4, a spacing member 8 made of a rolled steel material having a thickness of 4.5 mm, a width of 65 mm, and a height of 680 mm, for example, is connected by a U bolt 31 at a substantially central portion between the support columns 3 and 3.
The wire mesh 7 prevents pebbles and the like accompanying falling rocks from falling to the road side a, and the spacing member 8 disperses and transmits the tension to the entire cable 4 stretched up and down even with the tension applied to one of the cables 4.

Explaining the operation of the rockfall guard fence of the present invention, the impact energy of the rock receiving rope 6 and the wire net 7 that has received the rockfall is transmitted to the terminal columns 2, 2 via the buffer ropes 5, 5 connected to both ends of the rock receiving rope. However, the tension applied to the terminal struts 2 and 2 by energy absorption due to the elongation of the buffer ropes 5 and 5 and the wire mesh 7 having a large elongation is greatly reduced. Further, impact energy is transmitted to the upper and lower rock receiving ropes 6 that have not been directly subjected to falling rocks by the spacing member 8, and the energy is dispersed throughout the cable.

FIG. 5 shows a state where a falling rock collides with the falling rock prevention fence of this embodiment. When the falling rock 9 collides with the rope between the intermediate struts 3 and 3 from the stretched state of FIG. 5A, the rock receiving rope 6 attached to the intermediate strut 3 is slidable as shown in FIG. 5B. It extends to the road side a and absorbs rockfall energy to mitigate damage such as deformation of the struts. However, buffer ropes 5 and 5 with small longitudinal elastic modulus and large elongation are connected to the end struts at both ends of the rock receiving rope 6. Therefore, the energy is absorbed by the buffer ropes 5 and 5 extending greatly as shown in FIG. The buffer ropes 5 and 5 are easily damaged by falling rocks, but are arranged at both ends of the fence where falling rocks are less likely to collide, so that the weak points are covered and the advantages of high energy absorption characteristics can be fully exhibited. .
Further, the plurality of cables 4 and the wire mesh 7 are integrated by the spacing member 8, and the rock mesh energy can be absorbed by the metal mesh 7 and the plurality of cables 4 as a whole.

FIG. 6 shows a method of measuring tension when dynamic tension is applied to the rock receiving rope 6 and the buffer rope 5. A tension meter 91 is attached to the ceiling portion of the steel tower 90, and the tension meter 91 is 2 m in length. The rock receiving rope 6 was attached, and a weight 93 of 3 kN was attached to the end and dropped. The tension at that time was 200 kN. Similarly, when 2 m was attached to the buffer rope 5 and the weight 93 of 3 kN was dropped, the tension was 58 kN.
When the cable 4 is composed only of the rock receiving rope 6, a tension of 200 kN is applied to the terminal strut 2, whereas when the buffer rope 5 is used alone, a tension load of 58 kN is sufficient for the terminal strut 2. Therefore, conventionally, a terminal column corresponding to 200 kN is necessary, but according to the present invention, a terminal column corresponding to 58 kN is sufficient.

a mountain side b road side 1 rockfall protection fence 2 terminal support 3 intermediate support 4 cable 5 buffer rope 6 rock catching rope 7 wire mesh 8 spacing retainer

Claims (3)

Terminal struts erected at intervals along locations where rockfalls, avalanches, etc. of inclined surfaces should be prevented, a plurality of intermediate struts erected at intervals between the terminal struts, and terminal struts, In a rockfall guard fence equipped with a plurality of cables stretched at intervals in the vertical direction along the mountain side of the intermediate strut and a wire mesh stretched on the cable surface, the cable is smaller than the rock receiving rope. A rock fall protection fence characterized by comprising a buffer rope having a longitudinal elastic modulus and connected to both ends of the rock receiving rope. The rock fall protection fence according to claim 1, wherein the elongation P1 of the buffer rope is 20% ≦ P1 ≦ 65%, and the elongation P2 of the rock receiving rope is 4% ≦ P2 ≦ 6%. The rock fall protection fence according to claim 1, wherein a plurality of upper and lower stages of cables and a metal mesh are coupled with a spacing member, and the upper and lower stages of the cables and the metal mesh are integrated.

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