JPH0734419A - Shock absorbing device for dropped stone protective work - Google Patents

Abstract

PURPOSE:To give a specified impact relieving effect with small deformation and facilitate maintenance by reducing a load on a main body structure by reducing weight and also absorbing the kinetic energy of a dropped stone efficiency. CONSTITUTION:Multiple steel tubes of annular-cross section are arranged on a dropped stone protective work main body structure S to form a shock absorbing layer 3. A front plate 2a is set on the front side of the shock absorbing layer 3, and a rear plate 2b is set on the rear side of it. When a dropped stone 4 strikes the front plate 2a, the front plate 2a transmits the impact load distributedly to multiple steel tubes of the shock absorbing layer 3, and the impact load relieved by the deformation of the steel tubes is transmitted further to the main body structure S after being distributed by the rear plate 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock-absorbing device for rockfall lining installed on a steep cliff road or a railway track along a mountain or a coast.

[0002]

2. Description of the Related Art In a rockfall lining for protecting roads and human lives from rockfalls, a cushioning material or a cushioning device is installed on the roof part for the purpose of reducing the impact force generated by the collision of rockfalls.

For example, as shown in FIG. 4, rockfall lining 10
The sand cushion layer 12 is formed by laying mountain sand as a cushioning material on the roof portion 11 of the main body structure, thereby absorbing the impact of the falling rock 13 and absorbing the kinetic energy of the falling rock 13 ( Yoshida Sonoda, Hiroshi Sato, Nobutaka Ishikawa: Basic study on impact cushioning effect of sand cushion in rockfall lining, 47th Annual Conference of JSCE (September 1992) I-482, 1138- 113
(See page 9, Rockfall Countermeasure Guide: Japan Road Association, etc.).

In addition to this, Japanese Patent Laid-Open No. 4-265304 discloses a rockfall lining in which a concrete slab or a foam material is buried in a sand layer, and Japanese Patent Laid-Open No. 62-26840.
Japanese Patent Publication No. 8 discloses a rockfall lining in which the thickness of the sand layer is reduced by providing a sand cushion layer on a rubber block buffer layer composed of a large number of hollow rubber blocks.

[0005]

However, in order to absorb the kinetic energy of rockfall by the sand cushion layer, it is necessary to make the layer thickness considerably large, about 1 m, and the weight thereof is considerably large. There is a problem that the main body structure on which the cushion is installed also becomes large in size, and the construction cost of the entire structure increases.

Further, the sand cushion has a limit in the cushioning effect to be obtained, and the cushioning effect cannot be improved even if the thickness is increased more than the above.

Further, in the sand cushion, the sand is compacted with the passage of time, or the sand cushion collapses due to the collision of rockfalls. Therefore, in order to maintain the cushioning effect, it is necessary to periodically excavate the sand and replace the sand. There is also a maintenance problem.

In order to improve such problems, in the invention described in the above-mentioned Japanese Patent Laid-Open No. 4-265304, a sand cushion weight is obtained by embedding a foam material, a urethane plate or a concrete slab in the sand layer. And the buffering effect are improved.
In the invention described in Japanese Patent No. 408, the weight is reduced by replacing a part of the sand cushion with a lightweight material such as a rubber block.

However, since the foam material, urethane or rubber is expensive and may be deteriorated by ultraviolet rays, chemical substances, water, etc., it is necessary to exercise caution when using the foam material, and an appropriate method should be selected. There must be.

Further, in order to absorb the energy of rockfall by the foam material and the rubber, a considerable thickness is required, the construction cost becomes high, and the cushioning material constituted by them becomes large. Will end up.

The present invention is intended to solve the above-mentioned problems in the prior art, and by reducing the weight thereof, the burden on the main body structure is reduced and the kinetic energy of rockfall is efficiently absorbed. Accordingly, it is an object of the present invention to provide a shock-absorbing device for rockfall lining that can exhibit a predetermined shock-absorbing effect with a small deformation and is easy to maintain.

[0012]

A shock absorbing device for rockfall lining of the present invention comprises a plurality of steel pipes arranged in a single step or a plurality of steps on a main body structure of a rockfall lining to form a buffer layer, and elastic deformation of the steel pipe,
This is to reduce the impact load due to rockfall due to plastic deformation to reduce the burden on the main body structure.

If necessary, a surface plate or a back plate straddling a plurality of steel pipes may be provided on the rockfall collision surface of the buffer layer or on the surface opposite thereto to disperse the impact load.

Further, when the buffer layer is composed of a plurality of stages of steel pipes, by providing an intermediate plate for load distribution between the stages,
By forming a buffer layer having a multi-layer structure, it becomes possible to further improve the load distribution effect.

[0015]

In the shock absorbing device for rockfall lining of the present invention, the steel pipe is deformed in the elastic region and is almost restored after the impact, and a relatively large impact which is rarely generated, with respect to a relatively small impact that frequently occurs. On the other hand, assuming that it will be compressed and crushed to the extent that it will not be completely destroyed, it will absorb the energy of the rockfall by plastic deformation and by designing only the damaged part to be replaced later, The structure can be economically rational.

Further, by providing the surface plate on the upper portion of the steel pipe group arranged in parallel, it is possible to receive the impact caused by the collision of the rock fall on the surface and widely disperse the load and transmit the load to the plurality of steel pipes. In that case, since a plurality of steel pipes are deformed, the kinetic energy of rockfall can be absorbed with a small amount of deformation, and the impact force transmitted to the main body structure can be effectively mitigated.

That is, since the impact force applied at a point due to the collision of rockfall is transmitted to the main body structure through the front plate and the plurality of steel pipes or further through the back plate, the main body structure also transfers the load to the surface. Will be received at, which is more advantageous than if received at points.

Further, since the hollow steel pipes are arranged side by side, the weight can be reduced as compared with the conventional sand cushion and the like, and by changing the shape, material thickness and size of the steel pipe to be used, the cushioning effect and energy can be reduced. The absorption capacity can be set arbitrarily.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A shock absorber for rockfall lining according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows a shock absorbing device 1 for rockfall lining according to a first embodiment of the present invention. For example, a plurality of steel pipes having a circular cross section are arranged in parallel in one stage to absorb the shock. Layer 3
And a load distribution plate is provided on the rockfall collision surface and the surface on the opposite side.

In FIG. 1, reference numeral S indicates a main body structure of a rockfall lining, on which a shock absorber 1 is installed.

This shock absorber 1 is composed of both load distribution plates, a front plate 2a and a rear plate 2b, and a buffer layer 3 made up of a plurality of steel pipes installed between them, and a rockfall 4 is formed on the front plate 2a. collide.

The surface plate 2a is made of a combination of steel plates or steel materials arranged in a plane, a concrete slab, or the like. Since the surface can receive the impact caused by the falling rock 4, the load can be dispersed. It is transmitted to the plurality of steel pipes of the buffer layer 3.

The plurality of steel pipes of the buffer layer 3 under load undergo elastic deformation or plastic deformation to absorb the kinetic energy of the rockfall 4 while suppressing the impact force generated by the collision of the rockfall 4, and further to the back plate. It is transmitted to the main body structure S as a load that is distributed in a planar manner via 2b.

At this time, the arrangement intervals of the steel pipes can be set arbitrarily, and the steel pipes may be arranged so that the adjacent steel pipes contact each other, or the steel pipes may contact each other when they are compressed and deformed to some extent. However, the adjacent steel pipes may be arranged so as not to come into contact with each other even after the deformation.

In order to confirm the effect of the present shock absorbing device, for example, a steel pipe having a diameter of 450 mm, a wall thickness of 7 mm and a length of 1000 mm is used, and an interval of 750 mm is provided so that adjacent steel pipes do not come into contact with each other even after complete deformation. Consider a case where a rockfall 4 having a weight of 1 tf falls from a height of 10 m on the shock absorber 1 having a unit depth arranged as described above.

If the impact due to this collision is dispersed by the surface plate 2a and four nearby steel pipes take charge of it,
The generated impact force is approximately 50 tf, and the amount of compressive deformation of the steel pipe is approximately 220 mm.

On the other hand, in the conventional sand cushion, it is about 50 to 60 tf. Further, when the steel pipes are arranged at the above-mentioned arrangement intervals, the weight of the steel pipes is 1/15 or less of the weight of the 1 m thick sand cushion. Therefore,
Even if the weight of the load distribution plate is added to the weight of the steel pipe, a significant reduction in weight can be expected in this shock absorber compared to the sand cushion.

Further, in this shock absorbing device, the shock absorbing effect can be further reduced because the shock absorbing effect can be improved by changing the diameter, the wall thickness, the arrangement interval, etc. of the steel pipe to be used.

FIG. 2 schematically shows a shock absorber 5 according to a second embodiment of the present invention, in which the back plate is omitted and the shock absorbing layer 6 between the front plate 2a and the main body structure is a steel pipe. It has a structure in which the two are stacked and arranged in two stages.

In FIG. 2, the upper-layer steel pipe is fitted between the adjacent lower-layer steel pipes, but the upper-layer steel pipe may be arranged directly above the lower-layer steel pipe, or a multi-stage structure is also possible. Good.

In the second embodiment, steel pipes having a circular cross section are all used, but other shapes may be used, and combinations of several shapes may be used.

FIG. 3 schematically shows a shock absorber 7 according to a third embodiment of the present invention, in which an intermediate plate 9 is provided between the front plate 2a and the back plate 2b in the first embodiment, and A plurality of steel pipes are sandwiched between the face plate 2a and the intermediate plate 9 and between the back plate 2b and the intermediate plate 9 to form a buffer layer 8 having a two-layer structure.

In the shock absorber 7 of the third embodiment, the surface plate 2a
In addition to the load distribution due to the load distribution by the intermediate plate 9, a further buffering effect and energy absorption capability can be expected due to the dispersion effect by the intermediate plate 9. Further, the number of the intermediate plates 9 may be increased to two or more to further serve as a buffer layer having a multilayer structure.

Although a steel pipe having an elliptical cross section is shown in FIG. 3, a steel pipe having a circular cross section or another shape may be used.

[0036]

In the shock absorbing device for rockfall lining of the present invention, the energy of rockfall is efficiently absorbed by the deformation of a plurality of steel pipes arranged at a predetermined interval, and the impact force is mitigated. As compared with a cushioning material in which a sand cushion or a part of it is replaced with a foam material or a concrete slab, the generated deformation is small, and as a result, the cushioning device itself can be downsized and its weight can be reduced.

Further, by installing a load-dispersing front plate, back plate, or intermediate plate on the front surface or the back surface of the buffer layer, or in the middle, the shock caused by the collision of rockfall is received on the surface and the load is widely distributed. It can be transmitted to multiple steel pipes. In this case, since the plurality of steel pipes are deformed, the kinetic energy of rockfall can be absorbed with a small amount of deformation, and the impact force transmitted to the main body structure can be further effectively mitigated.

Therefore, it is possible to prevent the rockfall lining body structure from increasing in size, reduce the cross-section of its constituent members, and reduce the construction cost.

Further, since the shock absorber of the present invention has the shock absorbing layer composed of a plurality of steel pipes, the shock absorbing effect and the energy absorption capacity can be arbitrarily changed by changing the number, shape and size of the steel pipes constituting the shock absorbing device. Can be set to.

Further, for small-scale impacts with high frequency of occurrence, energy is absorbed by elastic deformation of the steel pipe, and for small-scale impacts with low frequency of occurrence, the steel pipe is not completely crushed. By allowing plastic deformation and thereby absorbing energy, it is possible to construct an economically rational shock absorber.

Further, it is normally maintenance-free, and when the shock absorber is damaged by falling rock, only the damaged part can be replaced, so that the maintenance after the completion becomes easy.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of a shock absorbing device for rockfall lining of the present invention.

FIG. 2 is a perspective view schematically showing a second embodiment of the shock absorbing device for rockfall lining of the present invention.

FIG. 3 is a perspective view schematically showing a third embodiment of the rockfall lining cushioning device of the present invention.

FIG. 4 is a vertical cross-sectional view showing a typical example of a conventional shock absorber for rockfall lining.

[Explanation of symbols]

S ... Main body structure, 1, 5, 7 ... Buffer device, 2a, 2b ...
Load distribution plate, 3, 6, 8 ... Buffer layer, 4 ... Rockfall, 9 ... Intermediate plate, 10 ... Rockfall lining, 11 ... Rockfall lining roof part, 12 ... Sand cushion, 13 ... Rockfall

Claims (3)

[Claims] 1. A shock-absorbing device for rock-fall lining, wherein a plurality of steel pipes are arranged in one or more steps on a main body structure of rock-fall lining to form a buffer layer. 2. A front plate or a back plate for distributing load across a plurality of steel pipes is provided on at least one surface of a front surface side which is a rockfall collision surface of the buffer layer and a rear surface side which is an opposite surface thereof. The shock absorbing device for rockfall lining according to claim 1. 3. The shock-absorbing device for rockfall lining according to claim 1, wherein the shock-absorbing layer is a shock-absorbing layer having a multi-layer structure in which a plurality of steel pipes are arranged in a plurality of steps with an intermediate plate for load distribution interposed between the steps. .