JP5666035B1 - Protective fence - Google Patents

Abstract

[PROBLEMS] To reduce the cost of a strut while reducing the load on the strut as compared with the conventional one. SOLUTION: A plurality of support columns 20 and a protection net 30 are provided, and an upper side of the protection net 30 is separated from the upper mountain side of the support column 20 by a predetermined distance X via an overhanging bracket 25 protruding from the upper portion of the support column 20. The bending moment toward the valley side and the bending moment Mu toward the mountain side generated in the column 20 at the time of receiving are configured to cancel each other. [Selection] Figure 3

Description

  The present invention relates to a protective fence that prevents disasters caused by avalanches, landslide, falling rocks, and the like, and more particularly, to a protective fence that reduces the load burden on a column.

  Patent Documents 1 to 3 disclose a protective fence in which the upper side of the protective net is connected to the upper part of the support and the lower side of the protective net is fixed to the slope mountain side.

JP 10-280333 A JP 2003-3425 A JP 2002-322615 A

The protective fences described in Patent Documents 1 to 3 have the following problems.
<1> When an impact load is applied to the protective net, an axial force and a bending moment (falling moment) toward the slope valley are applied to the support column. In particular, stress acts intensively on the base of the column.
Therefore, when designing the struts, not only do the struts have a large diameter so that they can withstand impact loads, or the steel pipes filled with concrete are used to design the struts with high strength. You must deepen the roots of the roots.
<2> When the diameter of the support is increased or the concrete is filled in the steel pipe in order to increase the strength of the support, not only the cost of the support is increased, but also the weight is increased and the transportability and handleability are deteriorated.
<3> Since the full length of the support becomes longer as the penetration depth of the support becomes longer, the problem of increasing the cost of the support and the longer the full length of the support, the worse the workability on the site and the workability at the work site.
In particular, when a high-rigidity support having a high unit price is used, the support cost is very high.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide at least one of the following protective fences.
<1> The load burden on the support can be reduced compared to the conventional case.
<2> To reduce support cost.
<3> Capability to improve supportability and handling of the support.

The present invention is a protective fence comprising a plurality of struts not provided with a trough side holding rope, and a protection net laid between the upper portions of the plurality of struts, wherein the lower side of the protection net is fixed to a mountain slope. The upper side of the protective net is attached to the upper mountain side of the column with a distance larger than the diameter of the column .
As an attaching means for the upper side of the protective net, a protruding bracket is projected on the upper part of the column, and the upper side of the protective net is separated from the upper mountain side of the column by a distance larger than the diameter of the column via the protruding bracket. Install.
The overhanging bracket has an opening engageable with the upper side of the protective net.
An extension strut may be added to the strut body to form a strut, and a strut joint may be formed in the vicinity of the point of change of stress generated in the strut .
A spacing member is placed between the upper portions of the columns as needed.
The protective net includes an anchor rope, and the lower end of the anchor rope is connected to the mountain side anchor.

Since the present invention has the above-described configuration, it has at least one of the following effects.
<1> Since the upper side of the protective net is supported at a predetermined distance from the support, the burden load on the support can be greatly reduced as compared with the conventional case.
<2> Since the burden load of the support becomes small, the design strength of the support can be lowered and economical design becomes possible.
<3> In the form in which the lower part of the support is built directly into the ground, the full length of the support can be reduced because the length of the support is reduced.
<4> If the overall length of the support is shortened, not only the drilling length is shortened, but also the transportation and handling of the support is improved.
<5> Even if a support column is formed by adding an extension column, if the column connection portion is formed in the vicinity of the stress change point, the column connection portion does not become a strength weak point.
Therefore, the protective fence can be used in a harsh environment where a huge load acts.

The perspective view of the guard fence which abbreviate | omitted the part which concerns on this invention Perspective view of the top of the column with some parts omitted Model diagram of protective fence according to the present invention Model diagram of protective fence for comparison without overhang bracket

  An embodiment of the present invention will be described with reference to FIGS.

<1> Protective fence Referring to FIGS. 1 to 3, the protective fence according to the present invention protrudes from a plurality of support pillars 20 erected on the ground 10 such as a slope with an interval, and to the upper mountain side of the support pillar 20. An overhanging bracket 25 is provided, and a protective net 30 is installed between these columns 20 via the overhanging bracket 25.
In the present invention, the upper side of the protective net 30 is attached to the upper mountain side of the support column 20 via the overhang bracket 25 at a predetermined distance, and the lower side of the protective net 30 is fixed to the mountain side anchor 11 on the mountain side slope. It is.
The main constituent members will be described in detail below.

<2> Protective Net The protective net 30 is a known net-like material that is laid on the mountain side between the columns 20 and includes various known protective nets.
The protection net 30 of this example includes a frame rope 31 that surrounds the top, bottom, left, and right peripheries of the net, a rope net 32 that is formed by crossing a plurality of rope members and attached to the entire surface of the frame rope 31, and a rope net 32 It is composed of a net 33 having a mesh size smaller than that of the attached rope net 32. Anchor ropes 34 are arranged on the frame rope 31 in the longitudinal direction in accordance with the pitch of the columns 20.
The materials of the frame ropes 31 and 34, the rope net 32, and the net body 33 may be any of known steel, fiber, and resin.

<3> Struts The struts 20 may be applied steel materials such as known mold steels and steel pipes, concrete columns, filled steel tubes in which steel pipes and concrete are combined, high-strength column bodies in which tensile materials and reinforcing steel materials are embedded in the filled steel tubes, and the like. it can.
The lower part of the support column 20 is built up in a built-up hole drilled in the ground 10 or is erected on foundation concrete built on site.

<4> Overhang Bracket An overhang bracket 25 protrudes horizontally on the top of the column 20.
The overhang bracket 25 is provided on the support column 20 in order to support the upper side of the protective net 30 so as to be separated toward the upper mountain side of the support column 20.
The embodiment illustrated in FIG. 2 will be described. The overhang bracket 25 is composed of a horizontal plate 26 that is fixed to the support column 20 and protrudes horizontally, and a vertical plate 27 that is provided so as to intersect the horizontal plate 26. A frame rope 31 and an anchor rope 34 can be connected through an opening 28 opened in a part of the bracket 25.

  The means for supporting the upper side of the protective net 30 is not limited to the illustrated overhanging bracket 25, and any structure that can support the upper side of the protective net 30 separately from the support column 20 is applicable.

<5> Interval Holding Material An interval holding material 22 is placed between the upper portions of the adjacent columns 20 so as to hold the interval between the columns 20 constant.
The spacing member 22 is a rigid member with excellent compression strength, and is formed of, for example, steel or cast iron.
The connection structure between the spacing member 22 and the column 20 illustrated in FIG. 2 will be described. The large-diameter top plate 21 provided on the top of the column 20 is provided with a coupling hole 21a, while the end portion of the spacing member 22 is provided. A connecting hole 23a is provided in the connecting bracket 23 provided in the connecting hole 23a, and a connecting element 24 such as a pin or a bolt is inserted into the connecting holes 21a, 23a so that the gap holding member 22 and the support column 20 are rotatably connected. Has been.
The spacing member 22 is not essential and may be omitted.

[Characteristics of protective fence]
Next, the characteristics of the protective fence according to the present invention will be described with reference to FIG.

<1> Absorption of Impact Load In the protective fence shown in FIG. 3, the upper side of the protective net 30 is supported on the upper mountain side of the support column 20 via the overhang bracket 25 at a predetermined distance X. The lower side is fixed to the mountain anchor 11.
When the impact load F directed toward the slope valley acts on the protection net 30, the protection net 30 is deformed, and the impact load F applied to the protection net 30 is supported by the strength of the mountain side anchor 11 and the column 20.

<2> Bending moment cancellation In the present invention, the burden load on the column 20 can be reduced by canceling the bending moment acting on the column 20 described below.

<2.1> Load transmission from the protective net to the overhanging bracket The impact load F acting on the protective net 30 is transmitted to the upper side of the protective net 30 and the engaging portion of the overhanging bracket 25, and the overhanging bracket 25 is It is transmitted to the upper part of the column 20 via.

<2.2> Component of impact load Since the upper side of the protective net 30 is supported at a distance X from the support column 20, the engaging portion between the protective net 30 and the overhanging bracket 25 is horizontally oriented toward the valley side. A component force A and a vertical component force B are generated.

<2.3> Bending Moment Generated in the Strut In the present invention, the impact load F applied to the protective net 30 is not directly transmitted to the strut 20 but is transmitted to the strut 20 via the overhang bracket 25. Thus, the horizontal component A toward the valley side generates a bending moment Md toward the valley side with respect to the column 20, and the vertical component B generates a bending moment Mu toward the mountain side with respect to the column 20.

The bending moment Mu toward the mountain side with respect to the support column 20 increases in proportion to the distance X.
The change point P of the stress generated in the support column 20 changes according to the length of the distance X.

<2.4> Mutual cancellation of moments Since both bending moments Md and Mu have opposite directions of action, the bending moments Md and Mu cancel each other, greatly reducing the bending moment acting on the column 20. be able to.
In other words, by supporting the protective net 30 separately from the support column 20 via the overhanging bracket 25, a bending force directed toward the slope mountain side acts on the entire support column 20. The bending force toward the slope mountain side attenuates and attenuates the force to bend the column 20 toward the slope valley side.
As described above, in the present invention, by supporting the upper side of the protective net 30 by separating the distance X from the support column 20, the burden load on the support column 20 itself can be reduced.
In particular, the burden load on the base portion of the column 20 is reduced.

<2.5> Advantages associated with the reduction of the load on the support column If the load on the support column 20 is reduced, the design strength of the support column 20 can be reduced, for example, by reducing the diameter of the support column 20, thereby allowing an economical design. .
Further, in the form in which the lower part of the support column 20 is built directly on the ground 10, the length of the support column 20 is shortened, so that the overall length of the support column 20 can be shortened.
If the overall length of the support 20 can be shortened, not only the drilling hole length will be shortened, but also the transportation and handling of the support 20 will be improved.

Further, in the snow protection fence, the burden load of the support column 20 may be extremely large, and the length of the support column 20 is increased in order to resist a huge snow pressure load, and as a result, the entire length of the support column 20 is increased. May be designed beyond the length of commercial steel products.
In the present invention, even if the column 20 is formed by connecting the column for extension to the column body, if the junction of the column 20 is formed in the vicinity of the stress change point P shown in FIG. The protective fence can be used in a harsh environment.
Further, it is possible to increase the interval between the support columns 20 as compared with the conventional case.

<3> Comparison Guard Fence FIG. 4 shows a model diagram of a comparison protection fence in which the overhang bracket 25 is omitted and the upper side of the protection net 30 is attached to the upper mountain side of the support column 20.
In the simultaneous protection fence, since the impact load F acting on the protection net 30 is directly transmitted to the upper part of the support column 20, the horizontal component A toward the mountain side and the vertical component force B are applied to the upper part of the support column 20. Will occur.

  The horizontal component force A toward the valley side generates a bending moment Md toward the valley side with respect to the support column 20, and the vertical component force B becomes an axial force of the support column 20, and the bending moment as in the protective fence of the present invention. There is no cancellation.

  In the guard fence shown in FIG. 4 in which the overhang bracket 25 is omitted, the bending moment Md and the axial force of the column 20 increase in proportion to the impact load F. In particular, the burden load on the base portion of the support column 20 is maximized. Therefore, the entire support 20 must be designed with high strength.

DESCRIPTION OF SYMBOLS 10 ... Ground 11 ... Mountain side anchor 20 ... Column 21 ... Top plate 21a ...... Top plate connection hole 22 ... Spacing retainer 23 Connection bracket 23a ... Connection bracket connection hole 24 ... Connection element 25 ... Overhang bracket 28 ... Overhang bracket opening 30 ...・ Protective net 31 ... Frame rope 32 ... Rope net 33 ... Net 34 ... Anchor rope

Claims (6)

A protective fence comprising a plurality of struts not provided with a trough-side holding rope, and a protective net laid horizontally between the upper portions of the plurality of struts, wherein the lower side of the protective net is fixed to a mountain slope,
The upper side of the protective net is attached to the upper mountain side of the support with a distance larger than the diameter of the support ,
Guard fence. An overhanging bracket projects from the upper part of the column, and the upper side of the protective net is attached to the upper mountain side of the column with a distance larger than the diameter of the column through the overhanging bracket. The protective fence according to 1.   The protective fence according to claim 2, wherein the overhanging bracket has an opening engageable with an upper side of the protective net. The protective fence according to claim 1 or 2, wherein a support post is formed by adding an extension post to the support main body, and a joint portion of the support post is formed in the vicinity of a stress change point generated in the support post .   The protective fence according to claim 1 or 2, wherein a spacing member is horizontally placed between upper portions of the support columns.   The protective fence according to claim 1 or 2, wherein the protective net includes an anchor rope, and a lower end of the anchor rope is connected to a mountain anchor.

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