JP2021075906A - Stone fall absorber - Google Patents

Abstract

To provide a stone fall absorber that has a small reduction amount of an upper edge of a net even if a stone falls and that can capture subsequent stone falls exactly so as to absorb energy.SOLUTION: A stone fall absorber comprises a net 1 for absorbing impact of a stone fall and a column 2 erected on an inclined plane. Guide holes 21 penetrated in the transverse direction are opened on the column 2. A plurality of guide holes 21 are opened at the upper side than the center and a singular guide hole is opened at the lower side. A slide wire 3 is inserted into each of the guide holes 21. The slide wire 3 at the upper side and the slide wire 3 at the lower side are taken as a pair and are fixed indirectly to a common braking device 5. Regarding other slide wires 3, each wire is fixed indirectly to the independent braking device 5. The other end of each slide wire 3 inserted into the guide hole 21 is connected to a corresponding position of a net support horizontal wire 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rockfall absorbing device that absorbs the energy of falling rocks and the like.

Various devices have been developed to absorb the energy of falling rocks from the slope and prevent subsequent damage.
For example, a technique as shown in Patent Document 1 is known.
This is due to the same applicant as in this case, but in the conventional rockfall absorber, the distance between the lower edge of the net and the ground is greatly separated at the time of a rockfall collision, and subsequent rockfalls pass through that distance. It was made by paying attention to the problem of. (Description of Patent Document 1 [0003] <c><d>)
The invention described in Patent Document 1 made to solve such a problem is composed of a guide column c and a net d having a through-through guide hole, and a slide wire a having one end fixed to the ground.
Then, one end of the pair of slide wires a inserted through the guide holes near the upper end and the lower end of the support column c is fixed to the braking device b, and the other end is fixed to the upper edge and the lower edge of the net d. (Fig. 7)
With this configuration, when the net d recedes to the valley side due to the impact of falling rocks, the upper slide wire a is pulled out, but the lower slide wire a also pulled out loosens, and therefore the net d collides. The falling rocks are guided downward. (Same as [0015])
At the same time, the effect that the distance between the lower edge of the net d and the ground surface does not widen can be expected. (Same as [0016] [0017])

Japanese Patent No. 4560223

About 18 years have passed since the invention described in Patent Document 1 described above, and a large number of construction results and actual tests have been repeated. As a result, it was found that there are the following problems.
<B> It was found that the occurrence of a gap between the lower edge of the net and the ground surface can be suppressed, but there is also the problem that the upper edge of the net is lowered.
<B> If the upper edge of the net, which should cover the jumping height of the rockfall assumed at the time of design, is lowered, the pillars will fall down (Fig. 8 of Patent Document 1), but the subsequent rockfall will be on the net. It means that there is a possibility of jumping over the edge.

In order to achieve the above object, the rockfall absorbing device of the present invention
A net laid on the slope to absorb the impact of falling rocks,
Consists of pillars established on the slope,
Guide holes are opened in the columns in the transverse direction and penetrated at multiple points, and slide wires are inserted into each guide hole.
At least any two slide wires are indirectly fixed to a common braking device as a pair.
Other slide wires are indirectly fixed to independent braking devices for each wire.
The other end of each slide wire through which the guide hole is inserted is connected to the corresponding position of the net support horizontal wire.

According to the present invention, at least one of the following effects can be obtained.
<B> As described above, the ordering party designs the rockfall absorption device assuming the upper limit of the jump height and the upper limit of the rockfall energy. And if rockfall energy = rockfall mass x collision velocity squared x 0.5, and if the jump height and rockfall energy are normally distributed, it is assumed that the frequency of medium-scale energy near the center will increase.
<B> When a rockfall collides with the center of the net, the center of the net is greatly deformed, and the slide wire at a position close to that position slides largely toward the valley side. However, the slide wire away from the collision position has a small amount of deformation because the amount of deformation of the net is small.
<C> Since the amount of sliding of the upper and lower wires is small, the amount of lowering of the upper edge of the net is small. As a result, it is possible to suppress the possibility that subsequent rockfalls will jump over the upper edge of the net.
<D> Due to the impact of falling rocks, the slide wire near the center slides largely to the valley side, and as a result, the other slide wires gradually slide to the valley side, and finally the top and bottom slide wires slide. , And so on, there is a time lag in the slide of the slide wire. Therefore, the effect of gradually absorbing the impact energy can be expected.
<E> Furthermore, the effect on the limit of the braking device can be expected. Since the braking device is fixed to the ground, the reaction force associated with braking must be less than or equal to the force of the anchor, the anchor force is proportional to the anchor length, and the anchor body also requires strength corresponding to the anchor force.
However, depending on the geology, the anchor force (adhesive force) per length of the anchor may not be large, and the anchor force is limited in consideration of cost effectiveness.
<F> For example, in the invention described in Patent Document 1, when trying to increase the allowable energy, it is theoretically possible to take measures such as increasing the braking force, increasing the thickness of the slide wire, and increasing the slide length. However, since the anchor force is limited as described above, it is difficult to increase the maximum energy absorption amount by this method.
In this respect, although the number of anchors is increased in the present invention, it is not necessary to expect a large value for the anchor force of one unit, and the effect that the maximum energy absorption amount can be expected can be expected.

The explanatory view of the Example when the rockfall collided with the rockfall absorbing device of this invention. Explanatory drawing of the attachment state of a support | slide wire and a support wire. Explanatory drawing of another Example 1. FIG. Explanatory drawing of another Example 2. Explanatory drawing of an embodiment of a braking device attached to the end of a slide wire. Explanatory drawing of an embodiment of the net. Explanatory drawing of a conventional rockfall absorber.

Hereinafter, examples of the rockfall absorbing device and the absorbing method of the present invention will be described with reference to the drawings.

<B> Net.
Net 1, which is a planar perforated body, is used to absorb the energy of falling rocks.
The width of the net 1 in the horizontal direction is such that the width between the columns 2 is composed of one net 1 for ease of handling, and the extension to the left and right is performed by connecting the ends of the net 1 with a shackle or a wire rope.
A wire mesh is generally known as the net 1.
In addition, as shown in FIG. 5, a large number of annular members 12 can be entwined with each other to form the net 1. In that case, since a large number of annular members 12 are entwined at regular intervals without being in close contact with each other, they have a high function of absorbing falling rocks.
The net supporting horizontal wire 11 is passed horizontally through the holes of the net 1 at the upper end, the lower end, and the intermediate position. The horizontal direction in this case is the horizontal direction in a state where the net 1 is stretched.

<B> Support.
The support column 2 is constructed by fixing a long material such as a square pipe or a circular pipe to a slope.
However, the support column 2 used in the apparatus of the present invention has a guide hole penetrating in the transverse direction of the central axis, that is, from the mountain side to the valley side in the vicinity of the upper side and the lower side thereof, and closer to the center and the upper side thereof. 21 is opened.

<C> Guide hole and slide wire.
A plurality of guide holes 21 are provided above the center of the column and a single guide hole 21 is provided below the center of the column.
Then, the slide wire 3 is inserted into each guide hole 21.
The slide wire 3 is a wire that functions to slide toward the valley side by the energy of falling rock when the energy of falling rock acts on the net 1.

<D> Braking device. (Fig. 5)
One end of the slide wire 3 is indirectly attached to the braking device 5 fixed to the ground in pairs of upper and lower parts.
In the braking device 5, for example, the space between the two spring steel plates 51 and the base 52 are joined by a bolt 53 penetrating the two, and the braking wire 54 is sandwiched between the steel plate 51 and the base 52.
Then, the ends of the two braking wires 54 on the net 1 side are collectively ice-price processed 55 in one place. On the other hand, the ends of the pair of slide wires 3 on the braking device 5 side are inserted into the ice price 55 of the braking device 5, folded back, and fixed with a wire clip in a tense state.
With such a structure, the braking wire 54 on the braking device 5 side slides even if the pair of slide wires 3 wins or loses at the top and bottom. For example, when the tension of the upper slide wire 3 is large and the slide wire 3 slides. , The phenomenon that the lower slide wire 3 sags occurs.

<E> Fixing the slide wire.
Of the three groups of upper slide wires, the uppermost slide wire a1 and the lower slide wire b1 are indirectly fixed to a common braking device as a pair.
The other slide wires a2, a3 ... On the upper side are indirectly fixed to the braking device 5 which is independent for each wire.
Since the braking device 5 has the above-mentioned structure, the braking wire 54 provided in the braking device 5 slides even if the upper and lower pair of slide wires a1 and b1 win or lose, and the upper end ride wire a1 When the tension is large and the slide wire b1 slides, a phenomenon occurs in which the slide wire b1 at the lower end sags.

<F> When opening multiple guide holes on the lower side as well.
In the specification of the present invention, for the sake of simplicity, an example in which a plurality of guide holes 21 are provided above the center and a single guide hole 21 is provided below the center will be described.
However, it is also possible to open a plurality of guide holes 21 on the lower side.
In that case, the structure in which the slide wire 3 at the nth stage from the top of the column 2 and the slide wire 3 at the nth stage from the bottom are indirectly fixed to the common braking device as a pair is the same.
In that configuration, a plurality of pairs of slide wires 3 are indirectly fixed to the common braking device 5 for each pair, and the other slide wires 3 are indirectly fixed to the independent braking device 5.

<To> Net expansion.
In the net 1, the net support horizontal wire 11 is passed through a large number of holes of the net 1 in advance.
On the 11th day of the horizontal wire, the entire net 1 is stretched by attaching the other end of the slide wire 3 at the position corresponding to the position, that is, the other end not fixed to the braking device 5.
At that time, for example, as shown in FIG. 1, the ends of the one-span net-supporting horizontal wires 11 are ice-price-processed, and the ice prices on both sides collected in front of the columns 2 and the slide wires 3 in the direction intersecting them at right angles. It is possible to adopt a configuration in which the ice price processed at the end is connected with a shackle and hung.
Ice-price processing is a technique for making a loop (eye) at the end of a wire rope to make a loading rope or a pedestal rope.

<C> Explanation of slides for slide wires.
When a rockfall occurs, it collides with the net 1, but as described above, the height of the upper edge of the net 1 is designed so that the orderer can prevent the height of the rockfall by assuming the limit of the jumping height of the rockfall. For this reason, ordinary rockfalls often collide with the center rather than the top.
Therefore, when the falling rock collides with the center of the net 1, the slide wire 3 at a position close to the receiving position first slides to the valley side of the slope greatly exceeding the braking force of the braking device 5.
At that time, the pair of upper and lower slide wires a1 and b1 in FIG. 2 also slide through the net 1, but the slide amount is small. Therefore, the lowering width of the upper edge of the net 1 is small, and the rising width of the lower edge is also small.
As a result, it is possible to greatly suppress the possibility that the subsequent rockfall jumps over the upper edge of the net 1 and jumps out from the lower edge of the net 1.

<Re> A mechanism that absorbs energy.
When a rockfall collides with the center of the net 1, the slide wire 3 near the center slides largely to the valley side, and then the upper and lower slide wires a1 and b1 gradually slide to the valley side due to the influence. As described above, there is a time lag between the slides of the slide wire 3. Therefore, the effect of gradually absorbing the energy of impact is produced.

<N> Slide difference between the upper and lower slide wires.
When the slide wire a1 at the uppermost end of the support column 2 slides due to the energy of the fall, the slide wire b1 at the lower end restrained by the same braking device 5 also slides by the same amount.
However, when the upper side of the net 1 bulges to the valley side more than the lower side due to the impact of falling rocks, the lower slide wire b1 is less affected by the falling rocks than the upper slide wire a1, and as a result, the lower side The slide wire b1 on the side is not tense and is in a slightly loosened state.
Therefore, a slack is generated below the net 1, and the colliding rock fall can be guided downward along the net 1.

<Le> Another Example 1. (Fig. 3)
In this embodiment, a plurality of guide holes 21 are provided on the upper side and the lower side of the support column 2.
Then, the slide wire 3 is inserted into each guide hole 21.
Then, at least a pair of slide wires a1 and a2 that are adjacent to each other at the top and bottom are attached to a common braking device.
The other wires 3 are attached to an independent braking device 5 for each wire 3.
The rockfall absorbing device having such a structure can be adopted when the net 1 is extended in the direction crossing the flow instead of the sabo dam.
Because it is difficult to install the braking device 5 in an orderly manner on such a steep terrain, it is often impossible to arrange the slide wires 3 at the upper end and the lower end, which are separated from each other, in combination as a pair. Because.
Moreover, the number of braking devices 5, that is, the number of anchors for fixing the braking devices 5, can be reduced as compared with the configuration in which each of all the wires 3 is attached to an independent braking device 5.
Further, it is not necessary to fix the adjacent columns 2 to the same braking device or to organize the slide wires 3.

<Wo> Another Example 2 (Fig. 4)
In this embodiment, a plurality of guide holes 21 are provided on the upper side and the lower side of the support column 2.
Then, the slide wire 3 is inserted into each guide hole 21.
Then, all the slide wires 3 are attached to the braking device 5 which is independent for each wire.
Similar to the case of the first embodiment, the rockfall absorbing device having such a structure can also be adopted when the net 1 is extended in the direction crossing the flow instead of the sabo dam.
This is because it is difficult to install the braking device 5 in an orderly manner on such a steep terrain, and it is often impossible to arrange a pair of upper and lower slide wires 3 in combination as a pair.

1: Net 2: Strut 3: Slide wire 5: Braking device

Claims (3)

A net laid on the slope to absorb the impact of falling rocks,
Consists of pillars established on the slope,
Guide holes are opened in the columns in the transverse direction and penetrated at multiple points, and slide wires are inserted into each guide hole.
At least any two slide wires are indirectly fixed to a common braking device as a pair.
Other slide wires are indirectly fixed to independent braking devices for each wire.
A rock fall absorber configured by connecting the other end of each slide wire through which a guide hole is inserted to the corresponding position of the net support horizontal wire. In the rockfall absorbing device according to claim 1,
Multiple guide holes are opened above the center of the column and a single guide hole is provided below.
The top slide wire and
The bottom slide wire is indirectly fixed to a common braking device as a pair,
The other slide wires were configured by indirectly fixing each wire to an independent braking device.
Rockfall absorber. In the rockfall absorbing device according to claim 1,
At least a pair of adjacent slide wires on the top and bottom are indirectly fixed to a common braking device.
The other slide wires were configured by indirectly fixing each wire to an independent braking device.
Rockfall absorber.

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