JP2016069932A - Protective net against falling object and reinforcement method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective net against a falling object capable of absorbing impact energy for a short time and efficiently; and a reinforcement method of the same.SOLUTION: A protective net 1 against a falling object comprises a support post 2 erected on a slope S for receiving a stone fall from the slope S, a horizontal rope 4a of the uppermost stage of which both ends are fixed to the side of the slope S and suspended in the slope width direction through the support post 2, and a protective net 8 hung down from the horizontal rope 4a of the uppermost stage to the lower part of the slope. A reinforcing rope 10 for reinforcing a protective net is bent and installed outside of the protective net 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fallen object protection net provided with a pocket type protection net provided on the front side of the slope in order to protect the fallen object from the slope and a method of reinforcing the fallen object protection net.

As this type of conventional technology, for example, a pocket-type rockfall protection net for preventing a road running through a mountain from falling rocks and avalanches is known.
As shown in FIG. 9, the rockfall protection net includes a plurality of struts 200 erected on the middle of the slope, and a plurality of horizontal ropes stretched in the slope width direction via the heads of these struts 200. 400 (400a, 400b), a vertical rope 500 suspended from the top horizontal rope 400a, and a wire mesh 800 supported by the horizontal ropes 400a, 400b and the vertical rope 500. Falling objects such as falling rocks are captured and accommodated between the wire mesh 800 and the slope S.

Further, as an improvement example of the above-described rock fall protection net, a rock fall protection net shown in Patent Document 1 is also known.
In this rock fall protection net, as shown in FIG. 10, shock absorbing shock absorbers 101 are incorporated at the ends of the ropes 100 used at various locations, and the ropes 100 are anchored on the slope side via the shock absorbers 101. Secure to. Moreover, when a shock is applied to a rope or a wire net with falling rocks, the shock is weakened by the buffer metal fitting 101. That is, by incorporating the buffer fitting 101, the rope and the wire net are prevented from being damaged.

Utility Model Registration No. 3143816

  By the way, according to the falling rock protection net having the above-described shock absorption capability, the shock energy acting on the protection net is released to the buffer metal and weakened. That is, after the impact energy is received by the protective net, the received impact energy is once released to the rope end and is absorbed by the shock absorber on the rope end side.

  For this reason, if an excessive impact is applied in a short time, the protective mesh will be damaged soon before the impact energy is transmitted to the buffer metal fitting, and depending on the extent of the disaster, it is necessary to replace the protective mesh. In particular, in the vicinity of the center of the protective net far from the shock-absorbing metal fitting, the damage rate increases because it takes time to transmit the collision energy.

  The present invention has been made in view of the above circumstances, and provides a falling object protection net capable of efficiently absorbing impact energy in a short time and a reinforcing method thereof.

In order to achieve the above object, the present invention is configured as follows.
That is, in order to protect the fallen object from the slope, the pillars erected on the slope and the lateral ropes whose both ends are fixed to the sides of the slope and suspended in the slope width direction via the pillars And a fallen object protection net provided with a protection net suspended below the slope from the lateral rope,
A reinforcing rope for reinforcing the protective net is bent and provided outside the protective net.

  In the present invention configured as described above, a reinforcing rope is bent and provided outside the protective net. For this reason, the initial impact energy is weakened by deformation of the protective mesh without reaching the reinforcing rope. Further, when the protection net is further deformed and the reinforcement rope is further applied, the remaining impact energy is weakened by both the reinforcement rope and the protection net.

  In other words, by providing a reinforcing rope outside the protective mesh, the loss of time during energy absorption is eliminated to avoid damage to the protective mesh, and further, the reinforcing rope is bent with respect to the protective mesh. The shock absorption rate is increased while taking advantage of the shock absorption capability of the.

Also, a vertical rope is provided from the horizontal rope to the lower slope,
The reinforcing rope may be provided so as to pass through an area defined by these horizontal ropes and vertical ropes, particularly above the center of the area.

  In this configuration, the reinforcing rope is provided so as to pass through a region partitioned by the horizontal rope and the vertical rope, particularly above the center of the region. That is, the reinforcement rope is provided so as to pass through the central region or the central upper portion of the section that is easily broken, thereby reducing the damage rate of the protective net provided in the section.

  Further, the reinforcing rope may be provided on a diagonal line of a region partitioned by the horizontal rope and the vertical rope.

  In this configuration, since the reinforcement rope is provided on the diagonal line, the installation span of the reinforcement rope is the longest in this section, and a large amount of energy absorption of the reinforcement rope can be secured.

The protective net is fixed to the horizontal rope and the vertical rope,
The reinforcement rope may be configured to be connected to a fixed portion between each rope and the protection net.

  In this configuration, the protective net is fixed to the horizontal rope and the vertical rope. The reinforcing rope is connected to a fixed portion between the protective net and each rope (the horizontal rope and the vertical rope). For this reason, the impact energy acting on the reinforcing rope does not act directly on the protective mesh, but is received with the fixed portion between the protective mesh and each rope as a fulcrum.

  Further, the bending degree of the reinforcing rope may be set so as to prevent the protection net from being broken.

  In this structure, when setting the bending degree of a reinforcement rope, the value which can prevent the fracture | rupture of a protection net | network is employ | adopted. That is, the reinforcing rope is acted before the protective net is damaged, and the damage of the protective net is avoided by the impact absorbing power of the reinforcing rope.

  Further, the bending degree of the reinforcing rope may be set so that the reinforcing rope can be broken prior to plastic deformation of the protective net.

  In this configuration, when the bending degree of the reinforcing rope is set, the bending degree is set so that the reinforcing rope is broken prior to the plastic deformation of the protective net. That is, by actively breaking the reinforcing rope, all the energy absorption amount of the reinforcing rope is drawn out, and the protection net is maintained.

  Further, the bending degree of the reinforcing rope may be set in a range of 102 to 110% as a bending rate with respect to the installation span.

Here, the installation span corresponds to the distance of one section to be installed by bending the reinforcement rope, and the deflection rate is defined by the actual length of the reinforcement rope with respect to the length of the section. That is, it can be said that the bending rate of the reinforcing rope having a length 1.5 times the current section is 150%, for example. In addition, it can be said that the bending rate of the reinforcing rope having double length is 200%.
In addition, when the bending rate of the reinforcing rope is set within such a range, the impact energy can be efficiently absorbed by both the protective net and the reinforcing rope while staying within a range in which the breaking of the protective net can be prevented.

  Further, a plurality of types of long and short reinforcing ropes may be provided at a location where the reinforcing rope is to be installed, and the bending condition of the long reinforcing rope may be different from the bending condition of the short reinforcing rope.

  In this configuration, since the bending rate of each reinforcing rope is made different, the impact energy absorption timing can be shifted. Moreover, even if one of the plurality of reinforcing ropes is damaged, the reinforcing rope that remains even if one of them is damaged can prevent the protection net from being damaged.

  In addition, the reinforcement structure comprised by the above-mentioned reinforcement rope is useful not only for an existing fallen object protection net but also for an existing fallen object protection net. That is, the reinforcing structure and the reinforcing method according to the falling object protection net of the present invention can be applied regardless of whether it is newly installed or existing.

Further, in the present invention, in order to protect the fallen object from the slope, the pillar is erected on the slope, both ends of the lateral rope are fixed to the side of the slope, and in the slope width direction via the pillar. A method for reinforcing a fallen object protection net by suspending and hanging the protection net from the lateral rope below the slope,
A reinforcing rope for reinforcing the protective net is bent and provided outside the protective net.

That is, this is a reinforcing method in which the reinforcing structure according to the present invention is applied to an existing or newly-installed falling object protection net. In addition, about a concrete reinforcement method, it applies to each above-mentioned structure.
Further, various items described in the means for solving the problem can be combined without departing from the problem of the invention.

  As described above, according to the present invention, it is possible to provide a falling object protection net capable of efficiently absorbing impact energy in a short time and a reinforcing method thereof.

FIG. 3 is an overall perspective view of the falling object protection net shown in the first embodiment. The top view of the reinforcement rope provided in a reinforcement site | part. The schematic diagram which shows the bending condition of the reinforcement rope with respect to a protection net | network. The side view which shows the state in which the fallen object collides with a protection net | network in the fallen object protection net | network shown in Embodiment 1. FIG. The side view which shows the state which the reinforcement rope extended in the falling object protection net | network shown in Embodiment 1. FIG. FIG. 6 is a front view of a falling object protection net according to a second embodiment. FIG. 10 is a front view of a falling object protection net according to a third embodiment. FIG. 6 is a front view of a falling object protection net according to a fourth embodiment. The perspective view which shows the conventional pocket type rock fall protection net. The perspective view which shows the example of improvement of the conventional pocket type rock fall protection net.

As shown in FIG. 1, the fallen object protection network 1 according to the present invention includes a plurality of support columns 2 erected at intervals in the width direction of the slope S, and each support column 2 with respect to the slope S. The suspension rope 3 was erected at an angle, the holding rope 7 (lowermost horizontal rope) stretched in the slope width direction below the slope S, and suspended from the head of each support column 2 to the holding rope 7. A plurality of vertical ropes 5, vertical auxiliary ropes 6 disposed between the vertical ropes 5, 5, and the vertical ropes 5 and the vertical auxiliary ropes 6 are provided so as to intersect with each other, and both ends are inclined side anchors 11. A plurality of upper and lower horizontal ropes 4 fixed to the upper and lower sides.
Of the plurality of upper and lower horizontal ropes 4, the uppermost horizontal rope 4 a is suspended in the width direction of the slope via the heads of the columns 2. The protective net 8 is suspended over the top.

  The front side of the slope from the uppermost horizontal rope 4 a to the holding rope 7 is partitioned in a lattice shape by the horizontal rope 4 and the vertical rope 5 described above, and the protective net 8 is partitioned by the horizontal rope 4 and the vertical rope 5. The contacted area is crossed from the outside (slope front side). And the pocket-shaped accommodating part 9 is formed between this protective net | network 8 and a slope.

  The protective net 8 is fixed to the ropes 4, 5, 6, and 7 using metal fittings such as cross clips and coupling coils at the contact points with the ropes 4, 5, 6, and 7, respectively. The intersections of the ropes 4, 5, 6, and 7 are also fixed together by a cross clip, a coupling coil, or the like, and the ropes 4, 5, 6, and 7 and the protective net 8 are rigid as an integral structure. It is like that.

In the falling object protection net 1 of the present invention, in addition to the various ropes 4, 5, 6 and 7, a protection net reinforcement rope (hereinafter referred to as a reinforcement rope) 10 is bent outside the protection net 8. Provided.
Hereinafter, a reinforcing structure using the reinforcing rope 10 according to the present invention and a reinforcing method thereof will be described in detail in the following embodiments.

[Embodiment 1]
In the first embodiment, the reinforcing rope 10 is installed in each of the sections P1 arranged in the uppermost stage among the areas partitioned in a lattice shape.
Each of the uppermost sections P1 corresponds to an entrance into the falling object protection network 1 and has the highest collision rate with falling objects. For this reason, in the present embodiment, each of the uppermost sections P1 is reinforced with the reinforcing rope 10 to avoid local damage of the protective net 8 and to maintain the entire fallen object protective net.

Specifically, as shown in FIG. 1, the reinforcing ropes 10 are provided so as to intersect with each other along the two diagonal lines per section.
The reinforcing rope 10 is fixed to the ropes 4 and 5 at the intersections with the horizontal rope 4 and the vertical rope 5. In addition, the reinforcement ropes 10 and 10 may be mutually connected in the center crossing part of the reinforcement rope 10. FIG. Thus, the reinforcement ropes 10 and 10 are made to intersect at the center of the section, thereby increasing the amount of energy absorbed in the center of the section having a high damage rate.

Moreover, in this Embodiment, as shown in FIG. 2 and FIG. 3, the reinforcement rope is comprised with a total of four ropes per 1 set of reinforcement ropes. Specifically, two types of long and short ropes 10a and 10b are prepared, and two ropes having different lengths are combined and used in total.
Further, the bending rates of the ropes 10a and 10b having different lengths are set to increase by 102 to 106% for the short reinforcing rope 10a and increase by 105 to 110% for the long reinforcing rope, as shown in FIG. Each of the ropes 10a and 10b can be bent and installed by providing an extra length with respect to the installation span.
In addition, when the installation span is described in view of FIG. 1, the length of the diagonal line in the section P1 corresponds to the installation span in the claims of the present invention.

Further, the bending rate is selected based on the results of various preliminary experiments conducted in consideration of the expansion / contraction rate and load resistance of the protective net 8, the longitudinal elastic modulus of the reinforcing rope 10, and the like.
Specifically, the scale of falling rocks etc. at each installation site of the fallen object protection net 1 is predicted and assumed, and the value that can prevent the breakage of the protection net 8 within the range, and the reinforcement rope 10 is the plasticity of the protection net 8. The deflection rate is selected so as to satisfy both of the values that break prior to deformation.

  Next, the impact absorption effect of the structure having the above-described reinforcing rope 10 will be described with reference to FIGS. 4 and 5. In addition, the following explanation assumes a rockfall collision.

  First, when the falling rock D is generated above the slope, the falling rock D enters the falling object protection net 1 while jumping off the slope S as shown in FIG. Further, most of the falling rocks enter the uppermost section P1 and collide with the protective net 8 in the area where the protective net 8 is laid. In addition, as shown in FIG. 5, the protective net 8 weakens the impact energy of the falling rock D while being bent outward due to the collision with the falling rock D.

  When the protection net 8 is further deformed and the protection net 8 leans against the reinforcement rope 10, the remaining impact energy further deforms the protection net 8 and breaks the short reinforcement rope 10 a among the reinforcement ropes 10. That is, the impact energy in the latter half of the collision is weakened by both the protective net 8 and the short reinforcing rope 10a.

Here, the bending rate of the short reinforcing rope 10a will be described in detail. The bending rate of the short reinforcing rope 10a is a value that can prevent plastic deformation of the protective net 8 as described above, and the plasticity of the protective net 8 by the reinforcing rope 10 is as follows. It is set so as to satisfy both of the values that break before deformation. Therefore, when the impact energy is received, the short reinforcing rope 10a breaks, but damage or breakage of the protective mesh 8 is avoided.
That is, in the present reinforcing structure, the short reinforcing rope 10a is applied to the protective net 8 before the breaking of the protective net 8 so as to keep the deformation of the protective net 8 within a range not to be broken.

  As described above, in the present reinforcing structure, by providing the reinforcing rope 10 in a state of being bent with respect to the protective net 8, the shock is weakened while making use of the shock absorbing capability of the protective net 8. In addition, the reinforcement rope 10 is provided outside the protection net 8 to eliminate the time loss during energy absorption to avoid damage to the protection net 8, and the reinforcement rope 10 is actively broken to prevent the reinforcement rope 10 from being damaged. The shock absorbing ability is pulled out to its upper limit. Furthermore, since the deformation of the protective net 8 remains within the range where it does not break, the fallen object protective net 1 can be repaired only by replacing the short reinforcing rope 10a in the event of a disaster.

  Of the reinforcing ropes 10 provided in the section P1, the long reinforcing rope 10b is a spare rope, and is effective against the next falling rock. That is, by providing the reinforcing ropes 10 in a double manner, a new damage to the protective net 8 during the repair period is prevented.

Further, when the impact energy cannot be absorbed by the short reinforcing rope 10a, the long reinforcing rope 10b is effective as a further reinforcement of the protective net 8.
That is, by changing the bending rate of the reinforcing ropes 10a and 10b, the impact energy absorption timing is shifted, so that the impact energy that is not partitioned by the short reinforcing rope 10a can be further weakened and absorbed by the long reinforcing rope 10b. I have to.

[Test Example 1]
Hereinafter, preliminary experiment 1 relating to the selection of the deflection rate is shown below.
1. Outline and purpose of the test To understand the relationship between the bending rate of the reinforcing rope and the damage state of the protective mesh for this reinforcing structure with the reinforcing rope outside the protective mesh.

2. Test Specimen and Test Content A Structure of Specimen A rectangular pedestal (frame) is formed with a φ16 mm vertical rope and a horizontal rope, and this gantry is regarded as one section on the uppermost stage shown in this embodiment, and an experiment is performed. That is, a protective net was applied to a frame made up of vertical ropes and horizontal ropes, and reinforcement ropes were installed in a crossing state diagonally from the outside.
B frame size length 5m × width 3m
C Protection net Wire diameter 4.0mm
D Vertical rope / horizontal rope specification φ16 General-purpose twisted rope of steel wire specified in JIS G 3525 E Reinforcement rope specification φ14 General-purpose twisted rope of steel wire specified in JIS G 3525 In this test, on each diagonal line Two reinforcing ropes were installed one by one.
F Handling of deflection rate In this test, in order to grasp the optimum value of the deflection rate with high accuracy, the deflection rate was selected using the deformation rate (deformation amount) of the reinforcing rope having a correlation with the deflection rate.
The deformation rate is an index that indicates how much the central part of the protective mesh (wire mesh) has been deformed from a reference line that connects both ends of the reinforcement rope with reference to the installation span. The deformation rate was determined with the possible amount of deformation of the protective net as 100%. Specifically, the deformation amount when a reinforcing rope having a deflection rate of 126% was used as a reference, and the deformation amount of the wire mesh at this time was determined to be 100%. Further, since the amount of change per unit% (the width of the measured value) can be obtained larger than the deflection rate, the deformation rate can be verified with higher accuracy by using this deformation rate together.
G Falling object The spherical concrete block 11KN that applies a dynamic load to the protective net is lifted by a crane and dropped from a predetermined height.
3. Test results

A Deformation rate 30-50% (Deflection rate 102.3-106.4%)
In this range of trials, the protection net and the vertical rope supporting the protection net were maintained sound, and the reinforcement effect of the reinforcement rope was clearly obtained.
B Deformation rate 60% (Deflection rate 109.2%)
In this trial, the reinforcing effect was weak, the protective net was damaged, and the weight could not be complemented.

4). Evaluation From the above experimental results, it was confirmed that the reinforcement rope was particularly effective at a deformation rate of 30 to 50% and a deflection rate of 102 to 106%.

[Test Example 2]
Subsequently, preliminary experiment 2 relating to selection of the deflection rate is shown below.
1. Outline and purpose of the test Understand the relationship between the bending rate of the reinforcing rope and the damage state of the protective netting in a structure in which two types of long and short reinforcing ropes with different bending rates are provided on the diagonal of the same section. To do.

2. Test Specimen and Test Content A Structure of Specimen A rectangular pedestal (frame) is formed with a φ16 mm vertical rope and a horizontal rope, and this gantry is regarded as one section on the uppermost stage shown in this embodiment, and an experiment is performed. That is, a protective net was applied to a frame made up of vertical ropes and horizontal ropes, and reinforcement ropes were installed in a crossing state diagonally from the outside.
B frame size length 5m × width 3m
C Protection net Wire diameter 4.0mm
D Vertical rope / horizontal rope specifications φ16 Steel wire general-purpose twisted rope E reinforced rope specification Long rope φ16 JIS G 3525 steel wire general-purpose twisted rope × 2 Short rope φ14 JIS G 3525 In this test, one set (long rope x 2 + short rope x 2) of reinforcing ropes was installed on the diagonal line for each section.
F Deflection rate In the same manner as in Test Example 1, the deformation rate was used together to select the deflection rate.
G Falling object The spherical concrete block 11KN that applies a dynamic load to the protective net is lifted by a crane and dropped from a predetermined height.
3. Test results

A Test No1
Reinforcement rope (long) Deformation rate 40% (Deflection rate 104.1%)
Reinforcement rope (short) Deformation rate 30% (Deflection rate 102.3%)
According to this trial, both the long reinforcing rope and the short reinforcing rope broke,
It is conceivable that both reinforcing ropes have insufficient strength and insufficient energy absorption.
B Test No2-No4
Reinforcing rope (long) Deformation rate 50-70% (Deflection rate 106.4-112.6%)
Reinforcement rope (short) Deformation rate 40-60% (Deflection rate 104.1-109.2%)
In this trial, the soundness of the long reinforced rope was maintained. The short reinforcement rope broke with the absorption of impact energy. That is, while achieving a high impact absorption rate with a short reinforcing rope, the soundness of a long reinforcing rope functioning as a backup reinforcing rope could be secured.
C Test No5
Reinforcement rope (long) Deformation rate 80% (Deflection rate 116.4%)
Reinforcement rope (short) Deformation rate 70% (Deflection rate 112.6%)
According to this trial, both the long reinforcing rope and the short reinforcing rope were broken, and the vertical rope supporting the wire net was also damaged.
4). Evaluation From the above experimental results, test no. Good results were obtained in trials 2-4.
That is, the effectiveness of the present reinforcing structure was shown by a combination of reinforcing ropes having a bending rate of about 105% to 110% (40 to 70% in terms of deformation rate).

  In addition, according to a further experiment by the present inventor, the same tendency was observed even when the specifications of the protection network were changed. That is, it can be said that the reinforcing effect exhibited by the reinforcing rope is uniquely found by the deflection rate of the reinforcing rope, regardless of the specifications of the protective net.

As described above, according to the present reinforcing structure, the reinforcement rope 10 is provided outside the protection net 8, thereby eliminating the time loss during energy absorption and avoiding damage to the protection net 8. By being bent with respect to 8, the shock absorption rate is increased while taking advantage of the shock absorption capability of the protective net 8.
As described above, in the present reinforcing structure, when the impact exceeding the energy absorption amount acts on the protective net 8 in a short time, the advantage is exhibited particularly.

[Embodiment 2]
In the second embodiment, the reinforcing rope 10 is installed with all the sections arranged in the uppermost row of the areas partitioned in a lattice shape as one section P2.

  Specifically, as shown in FIG. 6, a reinforcing rope 10 is installed in parallel with the lateral ropes 4 a and 4 b at the center portion between the uppermost lateral rope 4 a and the next lateral rope 4 b. Further, the total length of the reinforcing rope 10 is longer than the entire width of the protective net 8, and is bent and provided in the section P2 as in the first embodiment.

[Embodiment 3]
In the third embodiment shown in FIG. 7, as in the second embodiment, the reinforcing rope 10 is installed with all the sections arranged in the uppermost row as one section P2. Further, the difference from the second embodiment is that the reinforcing ropes 10 are not provided in parallel to the horizontal rope 4 but are provided in pairs on the two diagonals of the section.

[Embodiment 4]
In Embodiment 4 shown in FIG. 8, the reinforcing ropes 10 are individually installed in the entire section P of the laying area of the protective net 8. Further, in the same manner as in the first and third embodiments described above, one set of reinforcing ropes 10 is provided on two diagonal lines of each section P. For this reason, since the reinforcement rope 10 can be densely arranged in the entire laying region of the protective net 8, further improvement in the energy absorption rate can be achieved.

Thus, the reinforcing structure according to the present invention can be exemplified in various embodiments.
In addition, the above-described reinforcing structure of the falling object protection net 1 can be applied not only to a new installation, but also to an already installed falling object protection net. Moreover, the fallen object protection net | network 1 of this invention is useful not only as a fallen rock but as a protective measure against a landslide, a rock fall, and an avalanche.

DESCRIPTION OF SYMBOLS 1 Falling object protection network 2 Support | pillar 3 Hanging rope 4 Horizontal rope 4a Top horizontal rope 4b Second horizontal rope 5 Vertical rope 6 Vertical auxiliary rope 7 Pressing rope (bottom horizontal rope)
DESCRIPTION OF SYMBOLS 8 Protective net 9 Falling stone storage part 10 Reinforcement rope 10a Short reinforcement rope 10b Long reinforcement rope 11 Anchor body P Section P1 Each section of the topmost stage P2 All sections arranged in the topmost stage D Falling object S Slope

Claims (9)

In order to protect the fallen object from the slope, a support column erected on the slope, a lateral rope that is fixed to the side of the slope and suspended in the width direction of the slope via the support column, A falling net protective net provided with a protective net suspended below the slope from the horizontal rope,
A fallen object protection net, wherein a reinforcement rope for reinforcing the protection net is bent outside the protective net. A vertical rope is provided from the horizontal rope to the lower slope,
The fallen object protection net according to claim 1, wherein the reinforcing rope is provided so as to pass through an area defined by the horizontal rope and the vertical rope.   The fallen object protection net according to claim 2, wherein the reinforcement rope is provided on a diagonal line of a region partitioned by the horizontal rope and the vertical rope. The protective net is fixed to the horizontal rope and the vertical rope,
The fallen object protection net according to claim 2, wherein the reinforcing rope is connected to a fixed portion between the rope and the protection net.   The falling object protection net according to any one of claims 1 to 4, wherein the bending degree of the reinforcing rope is set so as to prevent the protection net from being broken.   The fallen object protection net according to any one of claims 1 to 5, wherein the bending degree of the reinforcement rope is set so that the reinforcement rope can be broken prior to plastic deformation of the protection net.   The fallen object according to any one of claims 1 to 6, wherein the bending degree of the reinforcing rope is set to be in a range of 102 to 110% as a bending ratio of the reinforcing rope with respect to the installation span. Protective net.   8. A plurality of types of long and short reinforcing ropes are provided at locations where the reinforcing ropes are to be installed, and the bending state of the long reinforcing ropes is different from the bending state of the short reinforcing ropes. Falling object protection net described in 1. In order to protect fallen objects from the slope, a support column is erected on the slope, both ends of the lateral rope are fixed to the sides of the slope, and suspended in the width direction of the slope via the support column, Is a method for reinforcing a falling object protection net suspended from the horizontal rope below the slope,
A method for reinforcing a fallen object protection net, characterized in that a reinforcement rope for reinforcing the protection net is bent outside the protection net.

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