JP7355426B1 - Rockfall protection net and its improvement method - Google Patents

Abstract

[Problem] To provide a means for preventing protrusion of the protection net (net) from impairing the safety of a road space in the event of a rockfall collision in an existing or newly installed pocket-type rockfall protection net. SOLUTION: Separately from a horizontal rope 30 arranged so as to be integrated with a net 20, at least one protrusion control member 40 is provided on the outer surface side of the net 20 so as not to be integrated with the net 20. [Selection diagram] Figure 1

Description

The present invention relates to a rockfall protection net and a method for improving the same.

Rockfall protection nets can be roughly divided into two types: pocket type and covered type.
Among these, the pocket-type rockfall protection net has pillars a installed on slope d, net b installed between pillars a, and net b that is stretched so as to be integrated with net b, as shown in Fig. 5. A horizontal rope c fixed to the slope is provided, and the falling rock e collides with the net, the impact is absorbed by the deformation of the net b and the horizontal rope c, and the falling rock e is moved between the slope d and the net b. It has the function of protecting the road f by guiding it down the slope in the space between.
Therefore, in the conventional design of rockfall protection nets, the strength of each member, the spacing of the horizontal ropes C, and the shock absorber installed between the horizontal ropes C and the anchors are determined according to the expected rockfall energy at the site. Whether or not this is the case is being considered.

In the following non-patent document 1, which is known as a practical book on rockfall countermeasures, the following description was added in accordance with the revision in 2017.
(Page 155) 5-5-2 Design concept and procedure When designing pocket-type rockfall protection nets, ensure the height so that falling rocks are guided to the openings without jumping over them, and reduce the expected rockfall energy. Determine the cross section of the member and the installation range to ensure absorption, and confirm that the stability of the anchor is ensured.Also, when installing on the roadside, the protrusion of the protective net in the event of a rockfall collision will affect the safety of the road space. Make sure it doesn't get damaged."

Rockfall Countermeasures Handbook (edited and published by Japan Road Association, revised first edition published on December 27, 2017)

In order to satisfy this requirement that ``the protrusion of the protection net in the event of a rockfall collision does not impair the safety of the road space,'' separate safety measures will be taken not only for newly constructed rockfall protection nets but also for existing rockfall protection nets. There were times when it was necessary.

Therefore, the present invention aims to provide a means for preventing the protrusion of the protection net (net) from impairing the safety of the road space in the event of a rockfall collision in an existing or newly installed pocket-type rockfall protection net. It is.

The present invention, which has been made to solve the above problems, provides a pocket-type structure that includes at least columns installed on a slope, a net suspended between the columns, and a horizontal rope arranged so as to be integrated with the net. This rock fall protection net is characterized in that at least one protrusion control member is provided on the outer surface of the net in a manner that it is not integrated with the net.
In the invention, the location of the protrusion control member relative to the net can be set at a height below the collision surface of the net.
In the invention, the location of the protrusion control member relative to the net can be set at a height equal to or lower than the horizontal rope that is placed directly below the collision surface of the net.
In the invention, the protrusion control material has flexibility, the protrusion control material is installed in a slackened state, the protrusion control material is provided with a buffer, and the protrusion control material has rigidity. , a configuration in which the protrusion control material is a combination of a flexible article and a rigid article, and/or a configuration in which the protrusion control material is a single article can be adopted.

Further, the present invention provides an existing pocket-type rockfall protection net that includes at least pillars installed on a slope, a net suspended between the pillars, and a horizontal rope arranged so as to be integrated with the net. As an improvement method for this, it is characterized by adding at least one protrusion control member disposed on the outer surface side of the net in such a manner that it is not integrated with the net.
In the above invention, it is possible to specify the placement location of the protrusion control material with respect to the net so that the net protrudes due to a collision of falling rocks that is assumed to occur at the installation site of the rockfall protection net, so as not to impair the safety of the road space. .

Further, the present invention provides an existing pocket-type rockfall protection net that includes at least pillars installed on a slope, a net suspended between the pillars, and a horizontal rope arranged so as to be integrated with the net. As an improvement method for this, at least one of the horizontal ropes that are integrated with the net on the outer surface side of the net is released from integration with the net, and the net is integrated with the net. It is characterized by its use as a protrusion control material for controlling protrusion.
In the invention, the horizontal rope to be released from integration with the net is specified so that the net protruding due to a collision with a rockfall that is assumed to occur at a rockfall protection net installation site does not impair the safety of the road space. It is characterized by

According to the present invention, the manner in which the net protrudes (protrusion position, protrusion direction, protrusion amount, etc.) upon collision with a falling rock can be controlled by the protrusion control member. As a result, it is possible to prevent the protrusion of the protective net (net) from impairing the safety of the road space in the event of a collision with a falling rock.
Additionally, when implementing additional safety measures for existing rock fall protection nets, it is necessary to add protrusion control materials to the outer surface of the net without integrating them into the net, or to repurpose existing horizontal ropes as protrusion control materials. It is now possible to deal with construction work, which requires a large burden, such as relocating the pillars to the mountain side (requiring further land acquisition), replacing the netting with a high-strength net, and adding horizontal ropes (almost re-construction). becomes unnecessary.

FIG. 1 is a schematic diagram showing the overall configuration of a rockfall protection net according to the present invention. Schematic diagram showing a modification of the protrusion control material. A schematic diagram showing the overall configuration of the rockfall protection net before and after adding protrusion control members. Photos showing the experimental results of the rockfall protection net before and after adding protrusion control materials. A schematic side view of a conventional pocket-type rockfall protection net.

Embodiments of the present invention will be described below with reference to the drawings.

<1> Overall configuration (Figure 1)
FIG. 1 shows the overall configuration of a rockfall protection net according to the present invention.
The rockfall protection net according to the present invention includes at least pillars 10, nets 20, horizontal ropes 30, and protrusion control members 40.
Further, the rockfall protection net according to the present invention may include, as other members, vertical ropes (not shown) arranged on the net 20 so as to intersect with the horizontal ropes 30.
The details of each component will be explained below.

<2> Support (Figure 1)
The support 10 is a member for suspending the net 20.
The pillar 10 is configured to be erected on a slope using other known methods, such as a method of fixing it via a foundation or anchor provided on the slope, a method of placing it on the slope and positioning it while separately taking a stand. .
A connecting portion (not shown) is provided near the head of the support column 10 to which various types of braces or various ropes can be connected or inserted.

<3>Net (Figure 1)
The net 20 is a member for receiving collision objects from the mountain side of the slope.
These collision objects include falling rocks, earth and sand, snowfall, avalanches, etc.
The shape and material of the net 20 are appropriately determined depending on the desired impact absorption performance against collision factors, and are not particularly limited in the present invention.
A particularly suitable example of the net 20 is a type of wire mesh (such as a rhombic wire mesh) that has spaces that are continuous in the lateral direction in the thickness direction.

<4> Horizontal rope (Figure 1)
The horizontal ropes 30 are members that are provided at predetermined intervals in the longitudinal direction of the net and are connected directly or indirectly to horizontal anchors provided on the slope.
The material, arrangement position, number of arrangement, etc. of the horizontal ropes 30 are appropriately determined depending on the desired shock absorption performance, and are not particularly limited in the present invention.
The transverse rope 30 is integrated with the net by an integration means 31, such as a coupling coil.
Further, in FIG. 1, the horizontal rope 30 is provided at one location at the upper end of the net 20, at two locations at the middle portion, and at one location at the lower end. A buffer device may be provided between the horizontal rope 30 and the anchor 32, which exhibits a buffering function by slipping when the horizontal rope 30 is subjected to a tension of a predetermined value or higher.

<5> Protrusion control material (Figure 1)
The protrusion control member 40 is a member for controlling the protrusion manner (protrusion position, protrusion direction, protrusion amount, etc.) of the net 20 at the time of collision with a falling rock.
The protrusion control member 40 is arranged on the outer surface side of the net 20 (on the front side of the paper in FIG. 1) in a manner that it is not integrated with the net 20, and extends in the width direction of the net 20 (in the left-right direction in the paper in FIG. 1). , the end of the protrusion control member 40 is directly or indirectly fixed to a fixed point (such as a slope or a foundation structure built on a slope).

<5.1> Regarding integration with the net In the present invention, "not integrated with the net 20" which specifies the arrangement mode of the protrusion control material 40 means "to avoid deformation or protrusion of the net 20 that occurs when a falling rock hits." Accordingly, it only means that the protrusion control material does not move or deform at the same time, and the interpretation is limited to the mode in which the protrusion control material 40 is arranged independently from the net 20 without using any coupling means. It's not something you do.
Therefore, in the present invention, the embodiments in which the protrusion suppressing material 40 is not integrated with the net 20 include an embodiment in which the protrusion suppressing member 40 is connected to the net 20 by a weak coupling coil or the like that is expected to break in the event of a collision with a falling rock. Naturally included.

<5.2> Examples of materials that can be used as protrusion control materials (Figures 1 and 2)
In the present invention, articles that can be used as the protrusion control material 40 include a single article that is flexible as a whole (flexible article), rigid as a whole (rigid article), or A composite article made by appropriately combining these can be used.

As the flexible article, a wire rope that can also be used as the horizontal rope 30 shown in FIG. 1 can be considered.

As shown in FIG. 2, rigid articles include those using a single pipe 42 (FIG. 2(a)), those using shaped steel 43 (FIG. 2(b)), and those using appropriate combinations of these members. etc. are possible. The material of each member is not particularly limited.

As a combination of a flexible material and a rigid material, as shown in FIG. 2(c), a wire rope 41 is inserted through a single tube 42 to make the single tube 42 rotatable.

<5.3> Tensioning degree of protrusion control material In the present invention, the protrusion control material 40 does not necessarily have to be in a tensioned state, but may be in a sagging state to cope with unevenness of the slope, etc. Good too.

<5.4> Arrangement location of protrusion control material In the present invention, the location (height) at which the protrusion control material 40 is arranged is such that the location (height) of the protrusion control material 40 is determined by Consideration will be made within a range that does not impair the safety of the space, for example, within a range where the intrusion of the net 20 into the "road space where safety is required" can be suppressed by arranging the protrusion control members 40.

(1) Definition of road space In the present invention, the "road space where safety is required" includes, for example, the space defined by the "construction limit" specified in Article 12 of the Road Structure Example. If separate regulations are specified in the Rockfall Countermeasures Handbook, etc., this shall also include the specified range.

(2) Example of considering the placement location of the protrusion control material When considering the placement location of the protrusion control material 40, the slope slope, the height from the road under the slope to be protected to the opening of the rockfall protection net, It is considered necessary to consider various factors such as the performance of each member.
An example of a study on the location of the protrusion control member 40 is shown below.

(2.1) Example 1: When the protrusion control material is placed at a height below the collision surface of the net.
In the present invention, the "collision surface 21 of the net 20" refers to "the rockfall collision position assumed when designing a rockfall protection net or during a performance test."
For example, when the net 20 is struck by a falling rock, the net 20 protrudes like a mountain in the vertical direction, with the collision surface 21 of the net 20 serving as the top of the mountain.
Therefore, in the rockfall protection net excluding the protrusion control material 40, if the net 20 protruding at a location below the collision surface 21 of the net 20 invades the road space where safety is required according to the rockfall countermeasure handbook, A method of arranging the protrusion control member 40 at a height below the collision surface 21 of the net 20 may be considered so as to suppress the amount of protrusion of the net 20 at this location.

(2.2) Example 2: When the protrusion control member is placed at a height lower than the horizontal rope placed directly below the collision surface of the net.
For example, the amount of protrusion of the net 20 at the time of a rockfall collision is affected not only by the energy absorbed by the deformation of the net 20 but also by the energy absorbed by the resistance of the horizontal rope 30. It is thought that the horizontal rope 30 directly below is the one that resists the collision of falling rocks the most.
Therefore, in the rockfall protection net excluding the protrusion control material 40, the net 20 that protrudes at a location below the horizontal rope 30 placed directly below the collision surface 21 of the net 20 is a road space where safety is required according to the rockfall prevention handbook. In order to suppress the amount of protrusion of the net 20 at that location, a protrusion control member 40 may be placed at a height lower than the horizontal rope 30 placed directly below the collision surface 21 of the net 20. It will be done.

<5.5> Number of protrusion control members In the present invention, the number of protrusion control members 40 arranged is not particularly limited, and is within a range that can suppress the net 20 from entering "road space where safety is required in the event of a rockfall collision." You can consider it.

<5.6> Effect of protrusion control member The protrusion control member 40 is arranged in such a manner that it is not integrated with the net 20, so that it is not affected by the deformation or protrusion of the net 20 that occurs when a falling rock collides with the net 20. Since it acts so as to remain at the same position (at the same height), it acts as if the net 20 were sliding relative to the protrusion control member 40. As a result, when compared with a rockfall protection net without the protrusion control material 40, the direction in which the net 20 expands changes, and the protrusion of the net 20 is suppressed around the area where the protrusion control material 40 is placed. become.

Furthermore, when a wire rope 41 inserted through a single tube 42 (FIG. 2(c)) is used as the protrusion control member 30, when the net 20 slides against the protrusion control member 40 during a collision with a falling rock, In addition, it can be expected that the single pipe 42 rotates as if it were a roller to promote sliding, and that the wire rope 41 inserted through the single pipe 42 is prevented from rubbing against the net 20 and being damaged.

<5.7> Additional aspect of protrusion control material The present invention is not limited to the aspect in which the protrusion control material 40 is incorporated in advance when designing a newly installed rockfall protection net.
For example, as a method for improving an existing rockfall protection net, a new protrusion control member 40 may be added to the existing rockfall protection net.
In addition, by releasing the integration with the net 20 (e.g., removing the integrating means 31) from among the horizontal ropes 30 incorporated in the existing rockfall protection net, the horizontal rope 30 may be repurposed as the protrusion control material 40. In this case, since the function as the horizontal rope 30 is lost, the maximum amount of absorbed energy allowed for the rock fall protection net will decrease, but if there is room in the original design, it can be adopted. There's room.
Furthermore, you may use these aspects in combination as appropriate.

<6> Experimental example (Figure 3, Figure 4)
Next, the results of a collision test on the rockfall protection net before and after adding the protrusion control material 40 will be described.

<6.1> Overall structure of rockfall protection net (Figure 3)
FIG. 3(a) is a front view photograph of a test specimen simulating a rockfall protection net before the addition of protrusion control members.
The composition of the test specimen is as follows.
Net: A diamond-shaped wire mesh with a width of 10 m and a height of 10 m is used.
Horizontal ropes: Placed at 5m intervals at the top, middle, and bottom of the net. Two shock absorbers were placed at both ends of the upper horizontal rope, one shock absorber was placed at both ends of the intermediate horizontal rope, and no shock absorbers were provided for the lower horizontal rope. Each horizontal rope is finally connected to anchors installed on concrete reaction bodies constructed on both the left and right sides.

FIG. 3(b) is a front view photograph of a test specimen in which a protrusion control member 40 was added to the configuration shown in FIG. 3(a).
The protrusion control member 40 was made of a wire rope made of the same material as the horizontal rope, and was arranged at one location below the horizontal rope in the middle, and two shock absorbers were arranged at each end.

<6.2> Test details For each test specimen, the maximum collision energy expected for the test specimen (in this example, a weight (1200 kg) mounted on a traveling pallet was run on a ramp from a height of 35 m. When a weight separated from a traveling pallet is collided almost vertically with a predetermined location of the net (a location sandwiched between the horizontal rope at the top end and the horizontal rope at the middle), the impact energy of 400 KJ is applied. The protrusion situation was observed from the side.

<6.3> Test results (Figure 4)
FIG. 4 is a transition photograph showing the behavior of the net during the collision test of the test specimen before and after adding the protrusion control material described in FIG. 3.
FIG. 4(a) shows the state before the protrusion control material 40 is added, and FIG. 4(b) shows the state after the protrusion control material 40 is added.
In FIG. 4(a), the net that protrudes after the collision of the weight invades the virtually specified road space.
On the other hand, in FIG. 4B, the net protrusion control by the protrusion control member 40 resulted in the net protruding after the collision of the weight not intruding into the virtually specified road space.

<6.4> Summary In this way, it is possible to control the protrusion mode, such as partially suppressing the amount of protrusion of the net, by simply adding protrusion control materials to preferred locations on the rockfall protection net.

A: Rockfall protection net 10: Support column 20: Net 21: Collision surface 30: Horizontal rope 31: Integrating means 32: Anchor 33: Buffer device 40: Protrusion control member 41: Wire rope 42: Single pipe 43: Shaped steel

Claims (4)

It includes at least a column installed on a slope, a net suspended between the columns, and a horizontal rope arranged so as to be integrated with the net, and the collision object that collides with the net is moved between the slope and the net. An improvement method for an existing pocket-type rock fall protection net that guides the net from the space between the rocks to the bottom of the slope,
A protrusion control material is arranged at least at one location on the valley side surface of the net so as to straddle the net in the lateral direction,
The protrusion control member fixes both ends of the protrusion control member directly or indirectly to a fixed point that includes at least the slope or a basic structure built on the slope, while also fixing one of the constituent elements of the rockfall protection net. It is characterized by being placed without being integrated with everything,
Method for improving rockfall protection nets. The method is characterized in that the location of the protrusion control material relative to the net is specified so that the net that protrudes due to the collision of falling rocks that is assumed to occur at the installation site of the rock fall protection net does not impair the safety of the road space.
A method for improving a rockfall protection net according to claim 1 . It includes at least a column installed on a slope, a net suspended between the columns, and a horizontal rope arranged so as to be integrated with the net, and the collision object that collides with the net is moved between the slope and the net. An improvement method for an existing pocket-type rock fall protection net that guides the net from the space between the rocks to the bottom of the slope,
At least one of the horizontal ropes is released from integration with all of the constituent elements of the rockfall protection net on the valley side surface of the net to control the protrusion mode of the net. Repurposed as a protrusion control material,
Both ends of the protrusion control member are directly or indirectly fixed to a fixed point that includes at least the slope or a foundation structure built on the slope, while the protrusion control member is straddled laterally over the net. characterized by placing
Method for improving rockfall protection nets. The present invention is characterized in that the horizontal rope to be released from integration with the net is specified so that the net that protrudes due to a collision of falling rocks that is assumed to occur at a rockfall protection net installation site does not impair the safety of the road space. ,
The method for improving a rockfall protection net according to claim 3 .