JP2006322321A - Fence preventing stone from falling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fence for preventing a stone from falling in which an energy absorption property of a rope can be utilized to a maximum extent, the diameter of the rope is reduced, and the generated tensile force is reduced. <P>SOLUTION: The fence for preventing the stone from falling is provided with sets of wire ropes arranged in plurality of tiers. In the fence, each of the sets of wire ropes comprises a wire rope with a predetermined length, and a wire rope with the length of the first wire rope plus the length larger than that of its elongation. When the stone falls, the shorter rope absorbs the falling energy in the plastic range in which the shorter rope is elongated to reach a yield point and is plastically deformed to continue its elongation until it is broken. After that, the longer rope absorbs the falling energy which was not absorbed by the shorter rope, and the secondary falling energy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rockfall prevention fence.

  As a rockfall prevention measure, there is used a rockfall prevention fence that includes a strut and one or more intermediate members arranged between the struts, a wire rope that is connected to the struts at both ends and the middle is connected to the intermediate member. And, the falling rock falls from the mountain side and the energy of the shocking load when it collides with the fence is absorbed by the wire rope.

  In that case, conventionally, the safety factor is designed to be 2 or more, and for each wire rope, the fall energy is absorbed within the elastic region of the rope (number 1 with a circle) as shown in FIG.

However, in this method of absorbing energy within the rope elastic region, the rope diameter increases and the generated tension increases from the viewpoint of energy absorption efficiency.
As a result, the workability deteriorated, and the anchor strength as the fixing portion had to be increased and increased in size in order to cope with the increase in the generated tension at the rope end. For this reason, construction costs increased, and the main bodies such as roads and bridges were adversely affected.

  The present invention has been made to solve the above-mentioned problems, and its object is to provide a rockfall prevention fence that can make maximum use of the energy absorption performance of the rope, reduce the rope diameter, and reduce the generated tension. There is to do.

  In order to achieve the above object, a rockfall prevention fence according to the present invention comprises a strut and one or more intermediate members arranged between the struts, a wire rope having both ends connected to the strut and the middle conducting the intermediate member. In the rockfall prevention fence provided in a multi-stage shape, the wire rope is a set of a wire rope having a predetermined length and a wire rope having a length equal to or longer than the length of the wire rope plus an extension amount, and is short when the rock falls. The fall energy is absorbed in the plastic region until the rope stretches, reaches the yield point, and continues to stretch until it breaks, and then the remaining fall energy and secondary fall energy absorbed by the short rope with the long rope It is characterized by being configured to absorb water.

  According to claim 1 of the present invention described above, a wire rope having a support column and one or more intermediate members arranged between the support columns and having both ends connected to the support column and the intermediate portion conducting the intermediate member is formed in a multistage shape. In the rockfall prevention fence provided in the above, the wire rope is a set of a wire rope having a predetermined length and a wire rope having a length equal to or longer than the length of the wire rope plus an extension amount. It absorbs the fall energy within the plastic region until it reaches the yield point and continues to stretch and breaks until it breaks, and then absorbs the remaining fall energy and secondary fall energy absorbed by the short rope with the long rope. As a result, the energy absorption performance of the rope can be utilized to the maximum, the rope diameter can be reduced and the generated tension can be reduced. And fall prevention is high, construction is excellent effect that it is possible to provide easy and inexpensive to implement an apparatus capable obtained.

It includes a form in which a long wire rope is positioned around a short rope.
According to this, since it looks like a single rope in appearance, the appearance is good, and it is possible to obtain an excellent effect that it is possible to prevent the extra length portion from shaking, the resulting noise, and damage due to collision with other objects.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
2 and 3 show an example in which the present invention is applied to a rock fall prevention fence installed at the boundary between a road and a mountain side.
6 is a support made of large H-shaped steel standing upright with anchors at predetermined intervals, 7 is an intermediate support placed on the support 6 and 6, and a wire rope in a normal tension state on the road side. 8 is stretched at regular intervals in the vertical direction, and a wire mesh 9 is stretched. The intermediate column 7 is floating or the lower end is lightly embedded in the base.

On the mountain side, a plurality of (two in the figure) wire ropes 3a and 3b having relatively different lengths L1 and L2 are stretched in a multistage manner.
The wire ropes 3a, 3b are positioned close to each other in the vertical and front-rear directions, and both ends in the longitudinal direction are connected to the support posts 6, 6 by rope end fittings 12 including an adjustment rod 12a, a socket 12b, and the like.
The middle of the wire ropes 3 a and 3 b is electrically connected to a guide fitting 13 fixed to the floating column 7.

The wire ropes 3a and 3b are not the same length, and one wire rope 3b has a length L2 that is relatively larger than the length L1 of the other wire rope 3b. The length L2 of the wire rope 3b needs to be a length obtained by adding the amount of elongation until the breakage of the wire rope 3a to the length L1 of the wire rope 3a, and an appropriate length is added thereto.
Of the wire ropes 3a and 3b, the relatively short wire rope 3a is stretched substantially linearly, but the relatively long rope 3b is slacked so as to form an arc between the floating columns 7 and 7. It is stretched.

  FIG. 4 shows a second example, in which the relatively long wire rope 3b is guided in a coil shape so as to surround the outer periphery of the short wire rope 3a. In this aspect, the fixing metal fitting is sufficient on one side, and the appearance is improved because it looks like one cord. It can also prevent the extra length of the long rope from shaking, the resulting noise, and damage from collision with other objects.

What is shown is only a few examples and is not limited thereto.
1) The configuration of the wire ropes 3a and 3b is arbitrary. The rope thickness is usually the same, but may be different.
2) Although the number of the wire ropes 3a and 3b may be one in appearance, at least two are required substantially. However, it may be increased according to the magnitude of energy to be absorbed. In other words, if the tension of the second rope does not satisfy the predetermined safety factor (usually more than twice), use the second rope up to the breaking zone and set the length of the second rope plus the length equal to or greater than the elongation. A third rope with it will be added. The same applies to the case of four or more.

The present invention includes struts 6 and 6 that are firmly planted, and one or more intermediate members 7 and 7 disposed between the struts, both ends being connected to the struts and the middle conducting the intermediate member. Wire ropes 3a and 3b are provided, and the wire rope is multi-staged, with at least a predetermined length of the wire rope 3a and a length of the wire rope 3a plus a length of the rope 3b equal to or greater than the extension amount. It is arranged.
When drawing the load / elongation curve of the rope in the process of absorbing the fall energy by the wire rope, it is as shown in FIG. 5, and the elongation increases linearly in the elastic region, and the curve goes to sleep after the yield point. . Conventionally, the portion up to the middle of the straight line portion is regarded as the energy absorption range. However, in the present invention, since the long wire rope 3b has a length longer than the elongation of the short wire rope 3a, the short wire rope 3a. Exerts the primary absorption action, and absorbs the falling energy within the plastic region (circled number 2) until it reaches the yield point and plastically deforms and breaks so that the elongation continues. It can be said that the short rope 3a functions as an auxiliary rope, and the long rope 3b finally functions as a main rope for preventing the fall.

Since the long wire rope 3b has a length longer than the elongation of the short wire rope 3a in the installed state, a tension is generated immediately after the short wire rope 3a is extended to the break or immediately before the break, and the short wire rope 3a is The remaining energy absorbed is absorbed until it breaks. That is, the residual fall energy and secondary fall energy of the object (here, the intermediate member) are absorbed. In other words, falling energy = energy absorption in the elastic region + energy absorption in the plastic region, and energy is absorbed by the circled numbers 1, 2 and 3 in FIG.
Since the plastic area of the rope is used for energy absorption in this way, the maximum possible absorption energy of each rope can be used, and the energy absorption amount is 3 to 4 times the elastic area. Therefore, in order to obtain load absorption energy equivalent to the conventional one, a thin diameter rope is sufficient.

More specifically, in the present invention, it is an essential condition that the last rope (n + 1) can support the fall weight in the elastic region, and the rope length and energy absorption satisfying the following formula are realized.
Formula (1) W * S <Es1 + Es2 +. . . + Esn + Es (n + 1)
Formula (2) Esn = 1/2 · σ · P · ΔLn + α · P · LRn · γ
Formula (3) ΔLn = (1 + ε0) · LRn · σ · P / (E · A)
Formula (4) Es (n + 1) = 1/2 · P / ΔL (n + 1) / SF
Expression (5) ΔL (n + 1) = (1 + ε0) · LR (n + 1) · P / SF / (E · A)

Here, W is the fall weight (N), S is the fall height (mm), s1 is the fall height of the first rope, s2 is the fall height of the second rope, and sn is the final 1 The fall height of the previous rope, s (n + 1) is the fall height of the final rope, E is the elastic modulus (N / mm ² ) of the rope, and σ is the coefficient at the elastic limit. 3 ≦ α ≦ 1.0. P is the rope standard breaking load (N), α is the efficiency in the plastic region, that is, the plastic deformation safety factor up to the rope breaking, and is usually 0.3 ≦ α ≦ 1.0. ΔL is the elastic elongation of the rope (mm), LR is the rope length (mm), γ is the elongation percentage of the rope in the plastic region (%), ε0 is the initial strain of the rope (%), SF is the safety factor of the rope, A is the cross-sectional area of the rope.

  Now, let's say that the fall energy is absorbed using two long and short ropes. That is, it is assumed that the short (auxiliary) rope is broken to absorb the fall energy, and then the remaining fall energy of the column is absorbed by the long (main) rope.

Assuming that the fall energy and the absorption energy of the rope (including the plastic region) are equivalent, the fall energy is Es1 = W · S1, Es2 = W · s2, and ΣEs = Es1 + Es2.
Since the absorption energy of the short rope is a plastic region, it can be calculated by the following equation.
Er1 = 1/2 · σ · P · ΔL1 + α · P · LR1 · r
ΔL1 = (1 + ε ₀ ) · LR1 · σ · P / (E · A)
Since the absorption energy of the long rope is within the elastic range, it can be obtained by the following equation.
Er2 = 1/2 · P · ΔL2 / SF
ΔL2 = (1 + ε ₀ ) · LR2 · P / SF / (E · A),
LR1 is the rope length (mm) of the short rope, and LR2 is the rope length (mm) of the long rope.

Now, the drop weight W is 2300N, the drop height s1 (primary drop distance) is 2985mm, the drop height s2 (secondary drop distance) is 626mm, the configuration is 6 × 19, the rope diameter is 16mm, and the standard breaking load is 117000N. , Effective cross-sectional area: 89 mm ² _{, a} rope having a rope length (LR1) of 2500 mm as _a short rope, a rope having a rope length (LR2) of 3000 mm as a long rope, and an elongation ratio r of the rope in the plastic region of 1.5 mm %, The coefficient σ at the elastic limit is 0.7, the efficiency α in the plastic region is 0.9, the initial strain ε _{0 of the} rope is 0.5%, and the safety factor SF is 2, the drop energy is Es1 = W · S1 = 686.6 kN · cm, Es2 = W · S2 = 144 kN · cm, and ΣEs = Es1 + Es2 = 830.5 kN · cm.

  The absorption energy of the rope is ΔL1 = 68 mm in the short rope, and Er1 = 673.3 kN · cm. In the long rope, ΔL2 = 58.3 mm and Er2 = 170.5 kN · cm. Therefore, the total absorbed energy ΣEr is 843.9 kN · cm. Since this is larger than the drop energy ΣEs of 830.5 kN · cm, it can be seen that the fall can be safely prevented.

On the other hand, in the general-purpose system, the following basic formulas (1) and (2) are established when the absorbed energy of the rope is equivalent to the dropped energy and the absorbed energy (including the plastic region) of the rope.
Formula (1) W * S = 1/2 * P * △ L * SF
Formula (2) (1 + ε ₀ ) · LR · P / (E · A)

When two wire ropes 3a and 3a having the same specifications as the present invention and having a length of 2500 mm are used (comparative example), the absorbed energy is as follows.
The drop energy W · S is 686.6 kN · cm, and the absorption energy Er of the rope is ΔL = 97.1 mm, so it is 284 kN · cm.
This is significantly lower than the drop energy W · S: 686.6 kN · cm, so it is unqualified and cannot be dealt with unless the thickness is increased to increase the strength.

It is a load-elongation curve figure which shows the energy absorption mechanism by the conventional rope. It is a front view which shows an example of the rock fall prevention equipment to which this invention is applied. (A) is a partially enlarged plan view of FIG. 2, (b) is a partially enlarged rear view, and (c) is a perspective view. It is a perspective view which shows the other example of the falling rock prevention equipment. It is a load-elongation curve diagram which shows the energy absorption principle of this invention.

Explanation of symbols

3a Short rope 3b Long rope 6 Post 7 Intermediate member

Claims (2)

A rockfall prevention fence comprising a strut and one or more intermediate members arranged between the struts, a wire rope having both ends connected to the strut and the middle connecting the intermediate member in a multistage shape, wherein the wire rope is A wire rope of a predetermined length and a wire rope with a length equal to or greater than the length of the wire rope plus the elongation amount are combined into one set so that when a rock falls, the short rope stretches to reach the yield point and continues to stretch further. Falling rock prevention, characterized in that the fall energy is absorbed within the plastic region until it is plastically deformed and fractured, and then the remaining fall energy absorbed by the short rope and the secondary fall energy are absorbed by the long rope. fence. The rock fall prevention fence according to claim 1 including a form in which a long wire rope is positioned so as to go around a short rope.

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