JP7430465B2 - Rockfall prevention equipment - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act November 10, 2020 At the 2020 Soil Science Center Foundation Lecture, we disclosed our research on ``A new source countermeasure method for unstable boulder clusters''.

The present disclosure relates to a rockfall prevention device.

Patent Document 1 discloses a standby type shock absorbing fence. This shock-absorbing fence includes a plurality of columns erected at predetermined intervals, a protective net stretched between the plurality of columns, and upper and lower side ropes with shock absorbers. When a falling object such as a falling rock collides with a part of the protective net, the protective net bends and deforms toward the valley side, and a part of the impact energy of the falling object is absorbed by the buffering action of the protective net.

Patent No. 6675631

However, in the method disclosed in Patent Document 1, there is a risk that small stones may slip through the mesh of the net, and improvements are desired.

The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a rockfall prevention tool that can suppress the fall of small stones.

The rockfall prevention device of the present disclosure includes:
A fixing part to the ground;
A rockfall prevention device comprising a rockfall receiving tray,
The tray portion includes a net body having a mesh, and a polyurethane foam attached to the net body in a form that closes the mesh.

According to the present disclosure, it is possible to provide a rockfall prevention device that can suppress falling of small stones.

1 is a diagram showing a rockfall prevention device according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view of the rock fall prevention device. FIG. 2 is a view of the rockfall prevention device seen from above the slope with a portion of the polyurethane foam removed. FIG. 3 is an explanatory diagram illustrating how the rock fall prevention device is used.

Here, a desirable example of the present disclosure will be shown.
The above-mentioned rock fall prevention device may include a connecting portion for connecting a portion of the receiving tray portion that is spaced apart from the fixing portion to the ground. According to such a configuration, the saucer portion can be supported at two or more points, and the posture of the saucer portion is stabilized.

It is preferable that the rockfall prevention tool described above includes a mechanism that changes the angle of the receiving surface of the receiving tray. According to such a configuration, stones accumulated on the receiving tray can be easily removed.

A rockfall prevention device 10 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 4. Note that the present disclosure is not limited to these examples, but is indicated by the scope of the claims, and is intended to include all changes within the meaning and range equivalent to the scope of the claims.

As shown in FIG. 1, the rockfall prevention device 10 is installed near the road R to prevent rocks from falling onto the road R. The rockfall prevention device 10 is small and easy to install, and is therefore suitable for preventing small-scale rockfalls onto narrow roads R. Road R, which is narrow in the mountains, frequently suffers damage from small-scale rockfalls. Damage caused by small-scale rockfalls often occurs when small stones directly collide with people or vehicles, or when small stones accumulate on road R over time. The rockfall prevention device 10 is installed in response to narrow roads R, which have been difficult to introduce due to cost, and allows the roads R to be used safely.

As shown in FIGS. 2 and 3, the rockfall prevention tool 10 includes a fixing part 11 to the ground G and a rockfall receiving tray part 20. The rockfall prevention device 10 of this embodiment further includes a connecting portion 30 and an angle changing mechanism 40. The angle changing mechanism 40 corresponds to a mechanism that changes the angle of the receiving surface 21 of the receiving tray section 20.

The fixing part 11 is a part for fixing the rock fall prevention tool 10 to the ground G. The fixing portion 11 is constituted by, for example, an anchor such as a ground anchor or a rock bolt. A support column 12 that supports the saucer section 20 is attached to the fixed section 11 . Depending on the installation range of the rockfall prevention device 10, only one fixing portion 11 may be provided, or a plurality of fixing portions 11 may be provided at predetermined intervals.

The tray portion 20 has a receiving surface 21 for receiving falling rocks. The receiving tray portion 20 is configured to be able to deposit fallen rocks received on the receiving surface 21 up to a certain amount. The shape and size of the saucer portion 20 are not particularly limited.

The tray portion 20 includes a net body 22 having a mesh 23 and a polyurethane foam 24 attached to the net body 22 in a form that closes the mesh 23. The net body 22 is stretched around the pillars 12 and constitutes a skeleton of the saucer portion 20. The polyurethane foam 24 is provided to cover the net body 22 from above and forms the receiving surface 21.

The net body 22 is made of, for example, a metal rope net, a fiber rope net, a diamond-shaped wire mesh, or the like. It is preferable that the net body 22 is provided in a state buried in the polyurethane foam 24. According to such a configuration, rust, deterioration, damage, etc. of the net body 22 can be suppressed by the polyurethane foam 24.

The polyurethane foam 24 is produced, for example, at the construction site using two liquid raw materials: a main component (liquid A) containing a polyol, a crosslinking agent, a blowing agent, etc. as a main component, and a hardening agent (liquid B) containing an isocyanate as a main component. It is formed by reacting. The polyurethane foam 24 is a two-component polyurethane foam. The curing time of two-component urethane foam is shorter than that of one-component polyurethane foam, and the raw material is less likely to fall down through the mesh 23 of the net body 22 before foaming and curing. The curing time of the two-component urethane foam can be appropriately designed depending on the extent to which the mesh 23 is covered by the polyurethane foam 24 and the thickness of the polyurethane foam 24 laminated onto the net body 22 .

The polyurethane foam 24 can be formed by spraying raw material onto the net body 22. Specifically, the builder sprays the raw material onto the net body 22 stretched on the pillars 12 from above the slope. Then, the liquid raw material adheres to the linear portions constituting the net body 22, and is foamed and hardened. The polyurethane foam 24 is formed in a form that closes the mesh 23 as the volume expands due to foaming. The polyurethane foam 24 of this embodiment is formed into a block or panel shape without holes. Preferably, the mesh 23 is completely filled with polyurethane foam 24 . The net body 22 has a different shape for each rockfall prevention device 10 depending on the condition of the ground G at the location where the rockfall prevention device 10 is installed, the installation range of the rockfall prevention device 10, deflection due to its own weight, etc. Since the polyurethane foam 24 is formed to follow the net body 22, there is no need for pre-forming it to match the shape and size of the net body 22.

The polyurethane foam 24 is preferably laminated to a predetermined thickness above the net body 22. The maximum thickness of the laminated polyurethane foam 24 is preferably 10 mm or more from the viewpoint of shock absorption. The upper limit is not particularly limited, but from the viewpoint of weight, it is preferably 2000 mm or less, more preferably 1000 mm or less. The portion of the tray portion 20 on the side of the ground G is more susceptible to the impact of falling rocks and the load of accumulated stones than the portion remote from the ground G. For this reason, it is preferable that the thickness of the laminated polyurethane foam 24 is greater in the region closer to the ground G than in the region farther away from the ground G. For example, the thickness of the laminated polyurethane foam 24 may increase from the end away from the ground G toward the ground G side.

The polyurethane foam 24 may be either a flexible urethane foam or a rigid urethane foam, but is preferably a rigid urethane foam. Rigid urethane foam is a foam that has higher hardness and lower resilience than flexible urethane foam. Rigid urethane foam can buckle and deform when impacted by a falling rock, allowing it to absorb the impact appropriately.

The expansion ratio of the polyurethane foam 24 is preferably 10 times or more, more preferably 20 times or more, and even more preferably 30 times or more, from the viewpoint of reducing the amount of raw materials carried to the construction site. The upper limit of the expansion ratio of the polyurethane foam 24 is not particularly limited, but is usually 40 times or less.

The connecting portion 30 is a portion for connecting a portion 25 of the saucer portion 20 that is spaced apart from the fixing portion 11 to the ground G. The connecting portion 30 constitutes an auxiliary fixing structure that distributes and receives the load related to the fixing portion 11. Further, in the present embodiment, the connecting portion 30 supports the receiving tray portion 20 at a location different from that of the fixing portion 11, and holds the receiving surface 21 in a posture facing in a predetermined direction.

The manner in which the connecting portion 30 supports the saucer portion 20 is not particularly limited. The connecting portion 30 of this embodiment supports the saucer portion 20 in a suspended manner. The connecting portion 30 is a so-called hanging rope. The connecting portion 30 has one end fixed to an anchor 31 provided on the ground G, and the other end fixed to a portion 25 of the saucer portion 20 located on the opposite side to the fixed portion 11. The connecting portion 30 of this embodiment is detachably fixed to the anchor 31.

The angle changing mechanism 40 is a mechanism for dropping falling rocks placed on the receiving surface 21 downward, as shown in FIG. The angle changing mechanism 40 is configured to change the angle of the receiving surface 21. The angle of this receiving surface 21 is changed between a first angle for receiving falling stones and a second angle for allowing falling stones to fall. The second angle is not particularly limited as long as it is an angle that allows the received stone to fall. In this embodiment, the receiving surface 21 is inclined with respect to the horizontal plane at the second angle.

The angle changing mechanism 40 can be configured by, for example, a hinge section provided on the fixed section 11. The tray portion 20 is attached to the fixed portion 11 via a hinge portion. The receiving surface 21 slopes downward toward the side opposite to the ground G at the second angle.

With reference to FIG. 4, the manner of use of the rock fall prevention tool 10 will be described. As shown in the figure on the left, the rockfall prevention device 10 is installed at a predetermined position and range based on the prediction of rockfall occurrence and the positional relationship with the road R. When a falling rock occurs, the receiving tray part 20 receives the falling rock, and the falling of the stone toward the road R side is suppressed. If the net body does not have the polyurethane foam 24 attached thereto, there is a concern that stones passing through the net may fall onto the road R. On the other hand, in the rock fall prevention device 10, since the polyurethane foam 24 is attached to the net body 22 in a form that closes the mesh 23, it is possible to suppress the falling of small stones.

As shown in the central figure, stones accumulate in the saucer portion 20 over time. Stones accumulated in the saucer portion 20 are periodically removed. Specifically, as shown in the figure on the right, the part of the connecting part 30 fixed to the ground G is removed, and the receiving surface 21 is moved from the first angle shown in the center figure to the second angle shown in the right figure. change the angle of Then, the stone placed on the receiving surface 21 falls due to its own weight and is removed from the receiving tray section 20. At this time, a loading platform or the like for transporting stones may be placed below the tray portion 20 to receive the fallen stones. Since the rock fall prevention device 10 is small, the angle of the receiving surface 21 of the receiving tray portion 20 can be easily changed by hand or using a small device. Thereafter, the connecting portion 30 is fixed to the ground G again, returning to the state shown in the left figure.

Note that the polyurethane foam 24 deteriorates when subjected to the impact of falling rocks and the load of accumulated stones, or when exposed to wind and rain. For this reason, part or all of the polyurethane foam 24 may be periodically removed along with the falling rocks, and the polyurethane foam 24 may be reattached. The polyurethane foam 24 requires less effort to install than structures such as the fixing part 11 and the net body 22. Therefore, by reusing the fixing part 11 and the net body 22, and by appropriately remaking the polyurethane foam 24, the rockfall prevention tool 10 can be used for a long period of time.

Next, the effects of the rockfall prevention tool 10 of this embodiment will be explained. According to the rockfall prevention device 10, falling of small stones can be suppressed compared to a rockfall prevention device including a net body to which the polyurethane foam 24 is not attached. Conventionally, nets have been used exclusively for rockfall protection, and the only way to prevent small stones from falling is to reduce the size of the net. For this reason, conventional rockfall protection measures have not been able to prevent stones smaller than the mesh from falling. The rockfall prevention device 10 uses polyurethane foam 24, which is lightweight and has a high ability to fill gaps, which has not been used until now, so that it is possible to suppress the falling of small stones, which could not be achieved conventionally.

Further, the polyurethane foam 24 absorbs the impact when a rock falls. Therefore, damage to the net body 22 and the fixing portion 11 due to falling rocks can be suppressed. Furthermore, since the polyurethane foam 24 absorbs the impact when a rock falls, it is possible to prevent the rock from bouncing off the receiving surface 21 and falling onto the road R side. Furthermore, when the polyurethane foam buckles due to the impact of a falling rock and is deformed so that a part of the stone is stuck in the polyurethane foam 24, the stuck stone can be stably held by the polyurethane foam 24.

Further, according to the rock fall prevention device 10, by using the polyurethane foam 24, the weight of the saucer portion 20 can be suppressed compared to the case where a net member with a finer mesh is used than in this embodiment. Particularly, when the rock fall prevention device 10 is installed in a mountainous area where roads are not maintained or on a slope where it is difficult to carry equipment, there is a problem that it is difficult to carry materials and equipment. The polyurethane foam 24 can be formed using simple equipment, and for example, the equipment can be transported to the site using a trolley, human power, or the like. In the method of this embodiment, raw materials and equipment for forming the polyurethane foam 24 can be easily transported, and the net body 22 with a large mesh can be used. As a result, it is possible to contribute to a reduction in the cost of transporting materials and equipment related to the formation of the rockfall prevention device 10.

Furthermore, by using the polyurethane foam 24, even if the shape of the net body 22 is complicated, the polyurethane foam 24 can follow the net body 22 and suitably close the mesh 23. Furthermore, the polyurethane foam 24 can be attached to the net body 22 by simply spraying the polyurethane foam 24 without any complicated installation work.

The rockfall prevention device 10 of this embodiment includes a connecting portion 30 for connecting a portion 25 of the receiving tray portion 20 that is spaced apart from the fixing portion 11 to the ground G. According to such a configuration, the saucer section 20 can be supported at two or more points, and the posture of the saucer section 20 is stabilized.

The rockfall prevention device 10 of this embodiment includes an angle changing mechanism 40 that changes the angle of the receiving surface 21 of the receiving tray portion 20. According to such a configuration, stones accumulated on the tray portion 20 can be easily removed.

<Other embodiments>
The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive.
The polyurethane foam may close the mesh of the net body, leaving some voids.
In the embodiment described above, the rockfall prevention device includes the connecting portion and the angle changing mechanism, but the rockfall preventing device does not need to include the connecting portion or the angle changing mechanism. In a configuration that does not include an angle changing mechanism, a tool may be used to remove stones that have accumulated on the receiving tray.

The number, arrangement, and shape of the fixing part, the saucer part, the connecting part, and the angle changing mechanism can be changed as appropriate. The connecting portion may support the saucer portion from below. The angle changing mechanism may be provided at a connecting portion between the connecting portion and the saucer portion.
The rockfall prevention device may be used for rockfall protection other than for preventing rocks from falling onto roads. For example, the rockfall prevention device may be installed on a slope adjacent to a house and used to prevent rocks from falling onto the house.

10... Rockfall prevention device 11... Fixing part 12... Strut 20... Receiver part 21... Receiving surface 22... Net body 23... Mesh 24... Polyurethane foam 25... Part (part of the receiver part separated from the fixing part)
30...Connection part 31...Anchor 40...Angle change mechanism G...Ground R...Road

Claims (3)

A fixing part to the ground;
A rockfall prevention device comprising a rockfall receiving tray,
The tray portion includes a net body having a mesh, and a polyurethane foam attached to the net body in a form that closes the mesh ,
The receiving tray portion has a receiving surface for receiving falling rocks,
In the rock fall prevention device, the polyurethane foam is provided to cover the net body from above and constitute the receiving surface . The rock fall prevention device according to claim 1, further comprising a connecting portion for connecting a portion of the receiving tray portion that is spaced apart from the fixing portion to the ground. The rockfall prevention device according to claim 1 or 2, further comprising a mechanism for changing the angle of the receiving surface of the receiving tray.

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