JP2000154510A - Shock absorbing type protection fence - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb a shock without relying on a friction force of a wire in a shock absorbing type protection fence. SOLUTION: A rod with screw 30 is connected with a wire 14 through a turn buckle 38, the rod with screw 30 is inserted into an indentator 28, and the rod with screw 30 is engaged with the indentator 28 in the direction of wire tension by a nut 32 to be screw-fitted in the rod with screw 30 in order to connect a wire for mooring a net with a support so as to absorb a shock. A pipe 26 is arranged between a tapered face 28A of the indentator 28 and the support 12. The indentator 28 expands the pipe 26 by a force generated when a shock is applied to the wire 14 to absorb a shock. Consequently, the shock can be absorbed by bellowslike buckling of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection fence to be installed under a cliff or the like, and more particularly to a shock absorption type protection fence having a function of absorbing a shock applied to a wire due to falling rocks.

[0002]

2. Description of the Related Art Protective fences installed at danger points of falling rocks, such as under cliffs, are constructed by mooring a net to a steel wire adjusted between columns. As a result, the falling rocks are caught by the net. The rigidity and strength of the wire
It is designed to catch the largest possible rockfall. For safety reasons, it is naturally recommended to assume as large a rockfall as possible, but taking too high a safety value results in increased costs. Therefore, some compromises have to be made as design values. Therefore, depending on a large rockfall exceeding the designed value, the load applied to the wire may exceed its breaking value or yield value, and the wire may break or the wire may be permanently deformed.

There have been proposed various types of wire provided with a buffer for protecting a protective fence against a large impact that may exceed the breaking limit or elastic limit of the wire. For example, Japanese Unexamined Patent Publication
In 173221, a loop portion is provided on a wire, and the wires are made to come into contact with each other under a fastening force applied by a screw-type gripper. When the load applied to the wire does not exceed a design value, the loop portion is formed. Maintains its loop shape without shrinking. Then, when a load exceeding the design value is applied to the wire, the wires slide against each other at the contact portion against the screw fastening force, and the loop contracts, so that the shock applied to the wire can be absorbed.

[0004]

Problems to be Solved by the Invention
In JP-A No. 1 (1994), the wires are brought into frictional contact with each other by a screw-type gripper in a loop portion, and when an impact force is applied to the wires, the wires are relatively moved at the contact portions against the frictional resistance between the contact portions of the wires. Shock absorption is performed. For this reason, there is a disadvantage that the wire surface is easily damaged by friction each time a shock is applied to the wire. In this case, depending on the degree of damage, it is necessary to replace the wire for safety measures.

Further, since the technique disclosed in the above publication absorbs the impact by the frictional resistance between the wires when the wires are tightened by the screw-type fasteners, even under the same screw tightening force, the wires can be used to determine whether or not there is oil. The frictional resistance changes due to the change in the surface condition, and the tension value when the loop contracts may change depending on the situation.

Further, in the prior art, the loop becomes smaller each time it receives an impact, so that it is difficult to straighten the wire when it is reused, and the wire often cannot be reused.

[0007] In order to solve the drawback of the above-mentioned method in which the wires are in direct contact with each other, it is conceivable to pass the wire through a pipe formed into a loop and apply a screw fastening force to the wire via the pipe. Although this method does not cause mutual contact between wires, there is no difference in relying on frictional force, so the above problems are inherent and pipes deformed by impact (the ring has become smaller) Another problem is that it is more difficult to remove the wire.

In view of the above problems, an object of the present invention is to provide a protective fence capable of absorbing a shock without relying on a frictional force of a wire.

[0009]

According to the present invention, there is provided a shock-absorbing protective fence having a shock-absorbing connecting device for connecting a wire to a support so as to be relatively movable against an impact load. The shock absorbing connection device comprises a pressure member attached to the wire, and a tubular pressure receiving member through which the wire is passed and which is disposed between the pressure member and the support. On the other hand, a shock absorbing type protective fence is provided in which the pressure member absorbs a shock by causing the pressure receiving member to cause plastic deformation gradually transmitted in the longitudinal direction.

In the present invention, the impact of the wire is absorbed by plastic deformation gradually transmitted to the pressure receiving member in the longitudinal direction. Therefore, the pressure receiving member needs to be replaced when the plastic deformation reaches the end, but since the wire does not absorb shock by its friction, there is no risk of damage due to friction unlike the conventional technology,
Reusable and economically advantageous.

The shock absorption is based on the plastic deformation of the pressure receiving member. The plastic deformation itself is determined by the material and its thickness, and the influence of friction is not directly affected. Therefore, the tension of the wire when the shock absorbing function is caused is always increased. It can be a constant value.

Further, even when the pressure receiving member needs to be replaced, the replacement is easy and the workability is not impaired.

[0013] In the present invention, pipe expansion can be used as plastic deformation of the pressure receiving member for absorbing shock. That is, the pressurizing member can be configured as an indenter having a tube expanding portion that engages with the pressure receiving member so as to expand the tube.
The impact applied to the wire is absorbed by the indenter gradually moving in the longitudinal direction in the pressure receiving member while causing the pressure receiving member to expand the tube.

By forming one end of the indenter as a tapered surface as the expanded portion, it is possible to cause expansion of the pressure receiving member with a simple shape.

[0015] The expanded portion may be an annular projection having a circular cross section on the outer periphery of the indenter. This structure has a small contact area between the indenter and the pressure receiving member, and thus has an effect of minimizing the influence of friction between the indenter and the pressure receiving member in the pipe expanding operation.

The expanded portion may be formed of an elastic material. In this case, the expanded portion is elastically deformed inwardly of the radius under a tension somewhat larger than the tension for expanding the pressure receiving member applied to the wire. Entrapment of foreign matter at the contact portion between the indenter and the pressure receiving member, galling, seizure, etc., increases the pipe expansion resistance, which can cause excessive tension on the wire.However, the pipe expansion section is formed of an elastic material. Therefore, if the expansion resistance increases, the expansion part elastically deforms inward in the radius, reducing the diameter of the indenter and reducing the expansion resistance, thereby preventing the occurrence of excessive tension on the wire. it can.

In the present invention, buckling can be used as another mode of the plastic deformation of the pressure receiving member for absorbing the impact. In other words, the pressure member has a plate shape in contact with the end face of the pressure receiving member, and at the time of impact, the pressure member causes the pressure receiving member to generate a bellows-like buckling that gradually advances in the longitudinal direction, thereby absorbing the impact applied to the wire. can do.

This is a very simple structure in which a plate-shaped pressing member is simply brought into contact with the end face of a cylindrical pressure-receiving member. The bellows-like buckling that progresses in the length direction is caused in the stable mode, and the cost can be reduced while obtaining a reliable shock absorbing effect.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a protective fence of the present invention is designated by reference numeral 10 in its entirety.
Is located at the place where rock falls, such as under a cliff. In this embodiment, the protective fence 10 is composed of a column 12 (one is visible in FIG. 1 but a plurality of columns are provided at predetermined intervals) and a wire (for example, a steel wire is stretched between the columns 12). Composed)
14 and a steel wire net 16 moored to the wire 14 by any suitable means known in the art. The net 16 in this embodiment fastens steel wires (single or stranded) 18 to each other at their intersections by fasteners 20,
2, a steel wire 18 is fastened to the wire 14.

The struts 12 are made of concrete in this embodiment, and wires 14 are stretched between the adjacent struts 12. In this embodiment, the shock absorbing connection device that connects the end of the wire 14 to the column 12 absorbs a shock by utilizing plastic deformation when expanding the metal tube. That is, as shown in FIG. 2, the connecting device includes a metal pipe 26 as a pressure receiving member and an indenter 2 as a pressing member.
8 and a threaded rod 30. The indenter 28 has a tapered surface 28A tapered toward the pipe 26 from an outer diameter portion larger than the inner diameter of the pipe 26. Pipe 26
Has a flange portion 29 on the column 12 side. The flange portion 29 is connected to the pipe 26 by means such as welding. Further, in the figure, the flange portion 29 is
The flange portion 29 may be fixed to the column 12 by a means such as an anchor bolt if necessary.

The threaded rod 30 has a threaded portion at one end,
The nut 32 is inserted into the indenter 28 through the second hole 12 </ b> A and the pipe 26, and the nut 32 is screwed into a screw portion protruding from the indenter 28. The threaded rod 30 has an ear portion 34 at the other end, and a pin 36 pivotally connected to the ear portion 34 has a ring portion 4 at one end of a screw fitting 40 extending from a turnbuckle body 38.
0A is inserted. A wire 1 is attached to a ring 42A at one end of a screw fitting 42 extending from the other end of the turnbuckle body 38.
The knot 44 at one end of 4 is inserted.

The installation of the protective fence 10 is performed as follows. First, concrete columns 12 are installed at predetermined intervals, and wires 14 are stretched between adjacent columns 12.
That is, with the turnbuckle body 38, the screw fittings 40 and 42, and the threaded rod 30 attached to the end of the wire 14 as shown in FIG.
A, a nut 32 is screwed into the tip of a rod 30 that is inserted into the pipe 26 and the indenter 28 and protrudes from the indenter 28.
A predetermined tension is applied to the wire 14 by turning the turnbuckle body 38. As will be described later, the predetermined tension value is appropriately smaller than the yield tension value of the wire 14, for example, about half of the yield tension value.

In the installation state of the wire 14, the taper 28A of the indenter 28 engages with the end of the pipe 26 under the tension of the wire, but in a normal state (a state in which the wire is not subjected to impact due to falling rocks). The pipe 26 is not expanded. After the wires 14 are tensioned between the columns 12, the net 16 is moored. That is, the steel wire 18 is hung on the wire 14 and fastened by the fastener 22, and the crossing portions of the steel wires 18 are fastened to each other by the fastener 20.

While the protective fence 10 is in use, the falling rocks etc.
6 received. At this time, the force applied to the wire 14 causes the indenter 28 to make its tapered surface 28A
When this force is greater than a predetermined value, the tapered surface 28A cuts into the end of the pipe 26, and the pipe 26 undergoes plastic deformation in the radial direction, that is, the pipe 28 undergoes expansion. In this way, the impact applied to the wire 14 due to falling rocks or the like is absorbed.

When the impact has subsided, the indenter 28
6 remains as shown in FIG. 3 and this state remains unless a new impact is applied.

When a new impact is applied to the wire 14 due to another falling rock or the like, the indenter 28 proceeds further inside the pipe while expanding the pipe 26, and stays at that position with the impact settled down.

When the bite of the indenter 28 reaches the end of the pipe 26, the impact absorbing function of the pipe 26 is lost. Therefore, the nut 32 is loosened, the used pipe 26 is taken out, and the pipe is replaced with a new pipe. The absorption function can be restored.

FIG. 4 shows the tension applied to the wire 14 and the indenter 2.
8 in the axial direction of the pipe (the indenter 28 shown in FIG. 2).
(A displacement of the indenter 28 along the pipe axis direction of the indenter at the time of impact from the initial position). As the displacement of the indenter 28 increases, the tension applied to the indenter 28 increases. When the tension applied to the indenter 28 increases to a predetermined value T (= expansion resistance) shown in FIG.
8A bites into the pipe 26, and as shown in FIG.
8 is completely immersed in the pipe 26.
Thereafter, as long as the tension applied to the indenter 28 does not reach the predetermined value T, the indenter 28 remains at that position in the pipe 26 and the indenter 2
When the tension applied to 8 reaches a predetermined value T, the expansion of the pipe 26 proceeds in the length direction. That is, the tension of the wire 14 does not exceed a predetermined value T that causes the pipe 26 to expand, and this is maintained until the indenter 28 reaches the end of the pipe 26. The magnitude of the predetermined value の of the tension is set to an appropriate value having a sufficient margin with respect to the yield stress value of the wire 14, but about half of the yield stress value is appropriate. On the other hand, the thickness of the pipe 26 is determined according to the material so that the pipe expansion (= plastic deformation) is caused by the set load Т.

FIGS. 5 and 6 show different forms of the indenter. In the embodiment shown in FIG. 5, the indenter 28 has a cylindrical shape, and has a substantially semicircular annular projection 46 formed on the outer peripheral surface thereof. The annular projection 46 is provided so as to engage with the pipe 26. Due to the impact applied to the wire, a radial force exceeding the elastic limit is applied to the pipe 26 by the annular projection 46,
The tube is expanded by plastic deformation, and the impact is absorbed.
In this embodiment, the sliding resistance due to the friction between the outer periphery of the indenter 28 and the inner periphery of the pipe 26 can be reduced as much as possible by engaging only the annular projection 46 with the pipe 26. Therefore, the influence of the sliding friction on the shock absorption characteristics due to the expansion can be reduced.

If necessary, a process of hardening the outer peripheral portion of the annular projection 46 in contact with the inner periphery of the pipe 26 by quenching or the like can be performed.

FIG. 6 shows a configuration in which the indenter 50 is formed as a cylindrical body formed of an elastic material, and a sleeve 52 as a support is provided behind the indenter 50. The radial elasticity of the indenter 50 is such that the pipe 2
6 is selected so as not to be deformed by the resistance force applied in the radial direction to expand the tube, but to be deformed by a force slightly larger than the expansion resistance.

FIG. 6 shows an embodiment in which the indenter 50 and the pipe 26 are used.
Even if the expansion resistance is increased due to foreign matter biting, galling, seizure or the like in the contact portion between the contact portion and the contact portion, this does not cause excessive tension of the wire, so that there is an effect that the protection of the wire is more complete. That is, if the pipe expansion resistance of the pipe 26 at the time of impact becomes larger than normal due to foreign matter biting, galling, seizure, or the like, the indenter 50 is elastically deformed inward in the radius and is reduced in diameter. The outer diameter is reduced accordingly. The tension applied to the wire is reduced due to the reduction of the pipe expansion resistance accompanying the reduction of the pipe expansion diameter, and the possibility of exceeding the elastic limit can be eliminated irrespective of the influence of, for example, the intrusion of foreign matter. Note that the elastic force of the indenter 50 can be appropriately set according to the plate thickness, material, and the like.

In a second embodiment to be described below, the use of a phenomenon in which when a load in the axial direction is applied to a circular section member such as a metal pipe, crushing (buckling) accompanied by bellows-like deformation at regular intervals is used. This absorbs the shock applied to the wire. That is, in the case of a completely plastic material that is not strain-hardened, buckling deformation of a circular or rectangular cross-section material occurs under an axially symmetric mode, and local swelling in the circumferential direction due to load reaches a limit value. It is said to occur in a bellows shape. For this phenomenon, see, for example, the description of “Automobile Research”, Vol. 20, No. 11, pp. 27-32. By the way, if a load exceeding the limit value is continuously applied, the bellows-like buckling is immediately transmitted to the end of the pipe, but the impact of falling rocks is instantaneous in the protective fence, and one or several bellows The impact applied to the wire after the deformation of the shape is reduced, and the impact absorption function of the wire due to the bellows-like buckling can be secured by a single pipe over a relatively long period against sporadic rockfall.

FIG. 7 shows a shock absorbing type connecting device for connecting the wire 14 to the column 12 in a second embodiment utilizing the bellows-like buckling phenomenon of a circular pipe. A pressing plate 128 as a pressure member, and a pressing plate 12 through a hole 12A of the support 12 and a metal pipe 126.
8 and a nut 13 screwed to the threaded rod 130 protruding from the push plate 128
And 2.

The shock absorbing operation according to the second embodiment will be described. When an impact is applied to the wire 14 due to falling rocks or the like, the pipe 126 is pressed in the axial direction by the push plate 128 to reduce the bellows-like buckling. receive. Since the impact of the falling rock does not last long, after several bellows-like bucklings, the axial load applied to the pipe 126 does not reach the buckling limit, and the buckling stops. This state is shown in FIG. When the wire 14 is again impacted by another falling rock, the bellows-like buckling proceeds one or more times in the axial direction of the pipe 126. In this way, when the bellows-like buckling has progressed to the end of the pipe 126, the pipe 126 is removed and replaced with a new one.

FIG. 9 shows a wire 14 according to the second embodiment.
7 is a graph schematically showing the relationship between the tension applied to the pressure plate and the displacement of the pressing plate 128 in the pipe axis direction. In this embodiment, the tension rises and falls in accordance with the period of the bellows-like buckling. The load at which the pipe 126 buckles is set to an appropriate value having a sufficient margin with respect to the yield stress value of the wire 14 as in the first embodiment, but about half of the yield stress value is appropriate. It is. Conversely, the thickness of the pipe 26 is determined according to its material so that the bellows-like buckling is caused by the tension value.

According to the experiment of the inventor, as long as a symmetrical load is applied to the pipe 126, stable bellows-like buckling can be caused, and the influence of its length is small. However, if the pipe 126 is too long, the symmetrical load is lost due to bending or the like, and there is a possibility that stable bellows-like buckling may not be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a shock absorbing fence of the present invention provided with a shock absorbing device of a first embodiment.

FIG. 2 is a cross-sectional view of the expansion-type shock-absorbing connection device of the first embodiment.

FIG. 3 is a view showing a state in which the expansion of the pipe has partially progressed in the shock absorbing connection device of FIG. 2;

FIG. 4 is a graph schematically showing the relationship between the displacement and the tension of an indenter in the shock absorbing connection device according to the first embodiment.

FIG. 5 is a view showing another form of the indenter in the expansion-type shock absorbing connection device.

FIG. 6 is a view showing still another form of the indenter in the expansion-type shock absorbing connection device.

FIG. 7 is a cross-sectional view of a connecting device that performs shock absorption by bellows-like buckling according to a second embodiment as a shock absorbing mechanism.

FIG. 8 is a view showing a state in which bellows-like buckling of the pipe has partially progressed in the shock absorbing connection device of FIG. 7;

FIG. 9 is a graph schematically showing a relationship between a displacement and a tension of a push plate in the shock absorbing connection device of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Protective fence 12 ... Prop 14 ... Wire 16 ... Steel wire net 26 ... Metal pipe 28 ... Indenter 28A ... Tapered surface 30 ... Threaded rod 32 ... Nut 38 ... Turnbuckle main body 46 ... Annular protrusion 50 ... Indenter 126 ... Metal pipe 128: Push plate 130: Rod with screw 132: Nut

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroki Saito 19-1 Gomijima, Fuji-shi, Shizuoka Prefecture F-term in Unipres Co., Ltd. (reference) 2D001 PA06 PC03 PD05 PE01 2D101 CA00 DA02 DA04 EA02 FA11 FA13 FA24 FA34 FA35 FB15 GA17

Claims (6)

[Claims] 1. A shock-absorbing protective fence having a shock-absorbing connecting device for connecting a wire to a support so as to be relatively movable against an impact load, wherein the shock-absorbing connecting device is connected to the wire. A pressure member to be attached and a cylindrical pressure-receiving member through which the wire is passed and disposed between the pressure member and the support, the pressure member in the longitudinal direction against an impact applied to the wire An impact-absorbing protective fence characterized in that impact is absorbed by causing plastic deformation which gradually propagates to the pressure receiving member. 2. The shock-absorbing protection device according to claim 1, wherein the pressure member is configured as an indenter having an expanded portion for engaging the pressure-receiving member so as to expand the tube. fence. 3. The shock absorbing protection fence according to claim 2, wherein the expanded portion is a tapered surface at one end of an indenter. 4. The shock-absorbing protective fence according to claim 2, wherein the expanded portion is an annular projection having a circular cross section on the outer periphery of the indenter. 5. The invention according to claim 2, wherein the expanded portion is formed of an elastic material and elastically deforms radially inward under a tension somewhat larger than the tension for expanding the pressure receiving member applied to the wire. Shock-absorbing protective fence characterized by: 6. The pressure receiving member according to claim 1, wherein the pressing member has a plate shape in contact with an end surface of the pressure receiving member, and causes the pressure receiving member to cause buckling which gradually progresses in a longitudinal direction upon impact. An impact-absorbing protective fence characterized by absorbing the impact applied to the wire.