US20200018022A1

US20200018022A1 - Uprightly-arranged support structure of protective fence

Info

Publication number: US20200018022A1
Application number: US16/256,962
Authority: US
Inventors: Yoichi Nishita; Taichi ISHII
Original assignee: Protec Engineering Inc
Current assignee: Protec Engineering Inc
Priority date: 2018-07-13
Filing date: 2019-01-24
Publication date: 2020-01-16
Also published as: JP6393850B1; JP2020012249A; KR20200007628A

Abstract

An uprightly-arranged support structure of a protective fence, the protective fence including: a plurality of supports arranged to stand at intervals, the plurality of supports having respective bottom portions thereof arranged to stand via a ground plate on a slope; and a protective net spread between the plurality of supports, wherein the bottom portions of the plurality of supports are arranged to stand so as to be slidable in conjunction with the ground plate in a predetermined direction on the slope.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is an application claiming priority, under the Paris Convention, on Japanese Patent Application No. 2018-133300 filed on Jul. 13, 2018, of which full contents are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a protective fence arranged to stand on a slope of a mountain side, on such a slope at a bottom of the mountainside, or the like, for capturing falling objects such as falling rocks, earth and sand, and avalanches. In particular, the present invention relates to an uprightly-arranged support structure of the protective fence of improved toughness and enhanced impact-absorption capability.

Description of the Background Art

In general, basic elements of a protective fence include a plurality of supports arranged to stand on a slope or the like at intervals, and a protective net mounted between an adjacent pair of the plurality of supports. In the enhancement of the impact-absorption capability of the protective fence, a shock absorber is placed in a portion of a rope member of which the protective net is made, or in a portion of a stay rope for holding the plurality of supports.
Most protective nets are those made of wire meshes, metallic or fibrous rope members, or a combination thereof. Steel members such as H-shaped steel or steel tube, concrete-filled steel tubes, concrete-filled steel tubes each having PC material embedded therein, and the like have been known for the plurality of supports. The material for the protective net and the plurality of supports has been selected in accordance with the impact-absorption capability of the protective fence.
In general, a protective fence has a structure to receive finally by a plurality of supports, impact force of falling objects such as falling rocks acting on a protective net and substantially on the plurality of supports. For this reason, such a structure having the plurality of supports arranged uprightly is important.
As an uprightly-arranged support structure, an embodiment having a plurality of supports arranged to stand in a non-inclinable manner, and an embodiment having a plurality of supports arranged to stand in an inclinable manner have been known.
As the embodiment having the plurality of supports arranged to stand in a non-inclinable manner, a further embodiment with the plurality of supports having their respective bottom portions rooted in a concrete foundation (Patent Document 1), and a still further embodiment with the plurality of supports having their respective bottom portions rooted deep in the ground of a job site (Patent Document 2) have been known.
The embodiment having the plurality of supports arranged to stand in an inclinable manner, which is a structure with a support arranged to stand inclinably on a ground plate without rooted in the ground, includes: a further embodiment having a hinge element provided at a bottom portion of the support (Patent Documents 3, 4); and a still further embodiment with a retention rope attached to an anchor for a support anchored into the ground, and inserted through a ground plate and hollow support so that an end of the retention rope is drawn out an upper end of the support and provided with a shock-absorbing metal fitting (Patent Document 5).
The embodiment having the hinge element provided at the bottom portion of the support is configured such that a shock absorber is placed in a portion of a stay rope for a support, and as a result, such a stay rope maintains the support in an upright manner under normal conditions, and slips so as to incline the support toward a valley side, by rotating the support around its hinge element, upon reception of impact.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Patent Application Publication No. 2003-034912 (FIG. 2)
Patent Document 2: Japanese Patent Application Publication No. 2007-205109 (FIGS. 1, 3)
Patent Document 3: Japanese Patent Application Publication No. 2007-032032 (FIGS. 1, 2)
Patent Document 4: Japanese Patent Application Publication No. 2009-144472 (FIGS. 1, 7)
Patent Document 5: Japanese Patent Application Publication No. 2001-107321 (FIG. 3)

Problems to be Solved

A conventional protective fence has the following problems to be solved.
[1] As disclosed in Patent Documents 1, 2, the protective fence having the plurality of supports arranged to stand in a non-inclinable manner is configured such that each support has a root fixed undisplaceably so as to withstand impact force and receive the transmitted impact force at a fixed position.
For this reason, a transmission time period over which impact force is transmitted from the protective net to each support is extremely short, and the impact force acts instantaneously on the support. As a result, a root portion of the support is suddenly bent before the impact-absorption capability possessed originally by the protective fence is exerted, and such a capability cannot be fully exerted.
[2] In the protective fence having the plurality of supports arranged to stand in an inclinable manner disclosed in Patent Documents 3, 4 is configured such that each support is inclined upon reception of impact. However, impact force acts instantaneously on the root portion of the support, and as a result, the impact-absorption capability possessed originally by the protective fence cannot be fully exerted.
[3] A general protective fence having a flexible structure is provided with a plurality of shock absorbers, and is configured such that impact force is absorbed by operations of such plurality of shock absorbers.
Impact-absorption capability of the protective fence is improved by using such plurality of shock absorbers; however, there is a need of the exchange or maintenance of members deformed after reception of impact.

SUMMARY OF THE INVENTION

The present invention is made so as to solve the problems described above, and an object thereof is to provide a structure having supports arranged uprightly of a protective fence capable of relaxing stress concentration on bottom portions of the supports, upon reception of impact, so as to prevent early deformation and buckling of the supports, thereby fully exerting impact-absorption capability possessed originally by the protective fence.

Means for Solving Problems

One aspect according to the present invention is an uprightly-arranged support structure of a protective fence, the protective fence comprising: a plurality of supports arranged to stand at intervals, the plurality of supports having respective bottom portions thereof arranged to stand via a ground plate on a slope; and a protective net spread between the plurality of supports, wherein the bottom portions of the plurality of supports are arranged to stand so as to be slidable in conjunction with the ground plate in a predetermined direction on the slope.
In another aspect according to the present invention, a plurality of slide holes are formed through the ground plate so that the ground plate is slidably fixed, through the plurality of slide holes, to a plurality of anchors for ground plate, which are the same in number as the plurality of slide holes.
In still another aspect according to the present invention, the plurality of slide holes are formed so as to be parallel to one another, and such a plurality of parallel slide holes may be along an inclination direction of the slope, or may be along a direction orthogonal to the inclination direction of the slope, or may be along a direction slant to the inclination direction of the slope.
In still another aspect according to the present invention, the plurality of supports and the ground plate may be of an assembly type, or may be integrally assembled in advance.
In still another aspect according to the present invention, the protective net is mounted between an adjacent pair of the plurality of supports as a span unit.

Advantageous Effects of the Invention

According to the present invention, by arranging the bottom portions of the plurality of supports to stand slidably in conjunction with the ground plate in the predetermined direction on the slope, the protective fence is capable of relaxing stress concentration on the bottom portions of the supports, respectively, upon reception of impact.
As a result, an early deformation and buckling of the supports can be prevented, and impact-absorption capability possessed originally by the protective fence can be fully exerted.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 depicts a perspective view of a protective fence, omitted partly, according to the present invention.

FIG. 2 depicts an exploded view of a support and a ground plate according to a first embodiment of the present invention.

FIG. 3 depicts a longitudinally cross-sectional view of the support and the ground plate.

FIG. 4 depicts an explanatory view of the support and the ground plate, of which: (A) is a plan view of the ground plate ruptured partially; and (B) is a cross-sectional view of (A) at a line B-B.

FIG. 5 depicts an explanatory view of a protective-fence's action capturing falling objects, in the form of schematically planar view of the protective fence before the supports slide.

FIG. 6 depicts an explanatory view of a protective-fence's action capturing falling objects, in the form of schematically planar view of the protective fence at a time when the supports are allowed to slide.

FIG. 7 depicts a plan view of a ground plate, according to a second embodiment of the present invention, which is perforated with slide slot holes formed in a Y-direction on a slope.

FIG. 8 depicts a plan view of a ground plate, according to a third embodiment of the present invention, which is perforated with slide slot holes formed in a slanting direction on a slope.

DESCRIPTIONS OF EMBODIMENTS OF THE INVENTION

Hereinafter, the present invention will be described with reference to the accompanying drawings.
In the descriptions, the inclination direction of a slope G is defined as a Y-direction, and a direction orthogonal to the inclination direction of the slope G is defined as an X-direction.

First Embodiment

[1] Outline of Protective Fence

Provided that the following explanations are made with reference to FIG. 1, the present invention is based initially upon a protective fence including a plurality of supports 10 (intermediate supports, terminal supports) arranged to stand at predetermined intervals, and a protective net spread between the plurality of supports 10.
Provided that the following explanations are made about the protective fence exemplified in an embodiment, each of the plurality of supports 10 is arranged to stand via a ground plate 30 on a slope G.
The plurality of supports 10 have their respective bottom portions slidable, in a predetermined direction on the slope G, in conjunction with the ground plate 30. Here, an embodiment having the plurality of supports 10 slidable in the X-direction on the slope G will be described.
A sliding structure allowing the plurality of supports 10 to slide will be described later.
A rope net 21 made of ropes and a wire mesh 22 smaller in mesh than the rope net 21, which are superposed on each other, are bridged between the plurality of supports 10. A protective net 23 includes the rope net 21 and the wire mesh 22.
An upper horizontal rope 21 a and a lower horizontal rope 21 b of the rope net 21 are coupled, at their respective both ends, between an adjacent pair 10, 10 of the plurality of supports 10.
The rope net 21 may be mounted between adjacent two pieces of the plurality of supports 10 as a span unit, or may be mounted among three or more pieces of the plurality of supports 10. In either of such embodiments, a seam between left and right sides of the rope nets 21 adjacent to each other is closed by coupling the left and right sides with a separate accouplement (rope or the like) so as not to be opened.
Furthermore, an interval retention cord 24 made of ropes is routed between upper portions of an adjacent pair 10, 10 of the plurality of supports 10, as a span unit, so as to retain a constant interval between the adjacent pair 10, 10.
The wire mesh 22 may be mounted to be suspended from the interval retention cord 24, or may be mounted on the rope net 21.
A mountain-side anchor 40 is arranged immediately above each of the plurality of supports 10 or arranged in between an adjacent pair of such supports 10, and a lateral anchor 41 is arranged at a lateral side of a terminal support 10.
Known anchors such as ground anchors and lock bolts are applied to such anchors 40, 41.
A mountain-side stay rope 45 is routed between an upper portion of each of the plurality of supports 10 and the mountain-side anchor 40, and a mountain-side positioning rope 46 is routed between each ground plate 30 and the mountain-side anchor 40.
A lateral stay rope 47 is routed between an upper portion of the terminal support 10 and the lateral anchor 41, and a lateral positioning rope 48 is routed between a bottom portion of the terminal support 10 and the lateral anchor 41.
In this embodiment, explanations are made about a protective fence of a type that the stay ropes 45, 47, and the rope net 21 including the horizontal ropes 21 a, 21 b are not provided with known shock-absorbing metal fittings; however, such an explained embodiment is also applicable to a protective fence provided with the shock-absorbing metal fittings.

[2] Support

Provided that the following explanations are made with reference to FIGS. 2-4, each of the plurality of supports 10 has slippage fastening pins 11 provided in a protruding manner, on outer peripheries at the upper and bottom portions of such supports 10, which slippage fastening pins 11 serve the purpose of fastening the interval retention cord 24, stay ropes 45, 47, and positioning rope 48 shown in FIG. 1 in an engaged state while they are wound around the outer peripheries.
Coupling means for such a plurality of ropes is not limited to a type of fastening by such slippage fastening pins 11. A bracket (not shown) provided in a protruding manner on each of the plurality of supports 10 to be coupled with the plurality of ropes may be alternatively applied.
An embodiment having the plurality of supports 10 each formed of a hollow tube body (a steel tube or the like) is described here; however, the plurality of supports 10 include known supports such as known steel members (H-steel and the like) and concrete-filled steel tubes.

[3] Ground Plate

The ground plate 30 is a load-transmitting plate for transmitting an acting load through the plurality of supports 10 to the slope G for load-bearing capacity, while positioning the bottom portions of the plurality of supports 10.
The ground plate 30 has an outer cylinder 31 provided uprightly from its upper surface, and the bottom portion of each support 10 is insertable into the outer cylinder 31 so that it can be inscribed in a cylindrical rubber plate 32 on an inner periphery of the outer cylinder 31.
The outer cylinder 31 is ribbed with a plurality of reinforcing ribs 34 arranged in a radial manner.
The bottom portion of each support 10 can be assembled with the ground plate 30 in such a manner that the bottom is inserted into cylindrical rubber plate 32 so as to be fit onto an inner periphery of the cylindrical rubber plate 32.
The outer cylinder 31 and the cylindrical rubber plate 32 may be in the form of a complete cylindrical body; however, they may also be in the form of a cylindrical-like body divided by vertical splits as illustrated in the relevant figures.
An embodiment with the plurality of supports 10 and the ground plate 30 configured to be of an assembly type is described here, for the purpose of facilitating conveyance of material to a job site and improving workability at the job site; however, the plurality of supports 10 and the ground plate 30 may be configured, as an alternative embodiment, such that they are coupled by fixing means such as welding or screwing.
It is to be noted that: an embodiment having the ground plate 30 with a connection hook 36 to be coupled with an end of the mountain-side positioning rope 46 is shown here; however, such an end of the mountain-side positioning rope 46 may be fastened by and coupled with the bottom portions of the plurality of supports 10 in a direct manner.

[4] Tension Structure of Support and Ground Plate

Provided that the following explanations are made with reference to FIGS. 2-4, each of the plurality of supports 10 is configured such that it is coupled in a tension state, via a tension member 50 inserted therethrough, to the ground plate 30.
The tension member 50 is a rope member insertable through each support 10, and has a bottom portion thereof fastened to a hanging hook 35 provided to stand in an upright position from the bottom surface of outer cylinder 31 on the ground plate 30.
The tension member 50 has a fastening bolt 51 connected integrally to the upper portion thereof, and the fastening bolt 51, through which an annular back plate 52 and a spring 53 mounted in order on an upper end of each support 10 are inserted, is screwed on by a fastening nut 54.
The tension member 50 is tensioned by tightening the fastening nut 54, and as a result, each support 10 and the ground plate 30 are clamped so that each support 10 can be maintained in an upright position with respect to the ground plate 30 is maintained.
The ground plate 30 may be laid so as to contact directly a surface of the slope G; however, such a ground plate 30 is improved in stability and bearing-pressure effect when it is placed on a mortar layer 44 for height adjustment constructed in advance on a surface of the slope G.

[5] Sliding Structure of Ground Plate

The ground plate 30 is fixed to the slope G such that it is allowed to slide in the X-direction on the slope G upon reception of impact. A sliding structure of the ground plate 30 will be described in detail with reference to FIGS. 2-4.

[5.1] Slide Hole of Ground Plate

Regarding the sliding structure of the ground plate 30, a plurality of slide slot holes 33, 33 are formed through the ground plate 30 in such an arrangement that the outer cylinder 31 is interposed therebetween on a plate surface of the ground plate 30. The plurality of slide slot holes 33, 33 are arranged in parallel to one another as well as parallel to the X-direction on the slope G.
A sliding distance of the ground plate 30 is determined on the basis of an entire slot length of the slide slot hole 33, and for this reason, the entire slot length of the slide slot hole 33 is selected appropriately in consideration of the impact-absorption capability of the protective fence, the installation situation of the job site, and the like.

[5.2] Anchor for Ground Plate

An anchor for ground plate 42 for fixing the ground plate 30 is a known anchor such as a lock bolt, and is arranged at a plurality of positions along the Y-direction on the slope G.
The installation number of the anchor for ground plate 42 is requested to be the same as that of the slide slot holes 33.
A screw to be screwed on by a nut 43 is formed on an above-ground exposed portion of the anchor for ground plate 42, and by screwing such a nut 43 on such a screw on the above-ground exposed portion inserted through each of the slide slot holes 33, the ground plate 30 is fixed to the slope G

Behavior of Protective Fence

Descriptions will be made on the behavior of the protective fence, the behavior of the plurality of supports 10 in particular, at the time of reception of impact with reference to FIGS. 5, 6. The basic action capturing falling objects such as falling rocks by the protective fence is the same as that of conventional techniques, and for this reason, descriptions thereof will be omitted herein.

[1] Behavior of Support Immediately After Reception of Impact

FIG. 5 shows a schematic planar view of the protective fence immediately after impact F of a falling object is received by the protective net 23, where the slide slot hole 33 of each ground plate 30 is arranged in parallel to the X-direction on the slope G.
Immediately after the impact F acts on the protective net 23, the protective net 23 starts being deformed in a swelling manner toward a valley side, and also the impact F acts, as tensile force f, on each of adjacent pair of supports 10, 10 through the protective net 23. The tensile force f on each support 10 acts, as displacement force f, on the ground plate 30 in the X-direction on the slope G.
When the displacement force f acting on the ground plate 30 in the X-direction on the slope G is smaller than the fixing strength of the ground plate 30 fixed through the anchor for ground plate 42, no displacement occurs for the ground plate 30. In other words, the arranged positions of the adjacent pair of supports 10, 10 do not change from the beginning, and also, a span L₁between the adjacent pair of supports 10, 10 does not change.
Accordingly, as in the case of the conventional protective fences, an impact energy is absorbed with the deformation resistance of the protective net 23 and the strength of each support 10.

[2] Sliding of Support

FIG. 6 shows a schematic planar view of the protective fence when a deformation amount of the protective net 23 is increased.
When the deformation amount of the protective net 23 is increased, the displacement force f acting on the ground plate 30 in the X-direction on the slope G is also increased.
When the displacement force f acting on the ground plate 30 in the X-direction on the slope G exceeds the fixing strength of the ground plate 30 fixed through the anchor for ground plate 42, the ground plate 30 is displaced in the X-direction on the slope G along the slide slot hole 33.
In other words, the arranged positions of the adjacent pair of supports 10 are displaced sideways from the positions at the beginning, and also, a span L₂between the adjacent pair of supports 10, 10 becomes slightly shorter in comparison with the span L₁before the displacement.
Even during the displacement of the bottom portion of each support 10 in the X-direction on the slope G, the impact energy is continuously absorbed as an impact absorber energy by the deformation resistance of the protective net 23 and the strength of each support 10.
In this manner, in an embodiment according to the present invention, the duration of load acting against each support 10 is made longer by accompanying the sliding displacement of each support 10 at a time when impact is received. It is possible, therefore, to avoid instantaneous action of a whole impact F on the adjacent pair of supports 10, 10.
A longer time period over the action of load means that impact force is gradually applied to each support 10.
Accordingly, it is possible not only for each support 10 to fully exert the originally possessed impact-absorption capability but also for the protective net 23 to fully exert is own impact-absorption capacity.
In other words, stress concentration on the bottom portion can be relaxed as well as sudden bending of the root portion can be prevented, with respect to each support 10.

[3] Propagating Action on Adjacent Span

Once a falling object hits a portion of the protective net 23, the protective net 23 positioned within the range of the impact is bent and deformed toward a valley side so that impact energy is absorbed by the bending deformation resistance of the protective net 20.
When the deformation amount of the protective net 23 is increased, the adjacent pair of supports 10, 10 are displaced mutually in an approaching direction, and the displacement force is propagated to some supports 10 not shown such that such supports 10 are sequentially drawn via the protective net 23 positioned exteriorly.
As a result, a span, which does not receive the impact, also performs the function of absorbing impact energy.

Second Embodiment

Hereinafter, other embodiments will be described in such a manner that the same portions as the above-described embodiments are provided with the same reference numerals, and detailed descriptions thereof are omitted.
Descriptions will be made, with reference to FIG. 7, on an embodiment having a bottom portion of the plurality of supports 10 is arranged so as to be slidable along the Y-direction on the slope G.
In this embodiment, a plurality of slide slot holes 33 are formed through the ground plate 30 in such an arrangement that: the plurality of slide slot holes 33 are along the Y-direction on the slope G; and as in the case of previous Embodiment 1, the plurality of slide slot holes 33 are parallel to one another on a plate surface of the ground plate 30.
As in the case of previous Embodiment 1, the plurality of slide slot holes 33 are in parallel relation.
As in the case of previous Embodiment 1, the ground plate 30 is fixed via the anchor for ground plate 42.
In this embodiment, at a time when impact is received, the bottom portion of each support 10 is slidable along the Y-direction on the slope G in conjunction with the ground plate 30 as a pressing plate. As in the case of previous Embodiment 1, by accompanying a sliding displacement of each support 10 upon reception of impact, stress concentration on the bottom portion of each support 10 can be relaxed, and the impact-absorption capability originally possessed by the protective fence can be fully exerted.

Third Embodiment

Descriptions will be made, with reference to FIG. 8, on an embodiment having a bottom portion of the plurality of supports 10 is arranged so as to be slidable along a direction slant to a direction on the slope G.
In this embodiment, a plurality of slide slot holes 33 are formed through the ground plate 30 in such an arrangement that the plurality of slide slot holes 33 are along the direction slant to a direction on the slope G.
In this embodiment, at a time when impact is received, the bottom portion of each support 10 is slidable along the direction slant to the direction on the slope G in conjunction with the ground plate 30 as a pressing plate. As in the case of previous Embodiments 1, 2, by accompanying a sliding displacement of each support 10 upon reception of impact, stress concentration on the bottom portion of each support 10 can be relaxed, and the impact-absorption capability originally possessed by the protective fence can be fully exerted.

Reference Numerals

10 support
11 slippage fastening pin
21 rope net
21 a upper horizontal rope
21 b lower horizontal rope
22 wire mesh
23 protective net
24 interval retention cord
30 ground plate, pressing plate
31 outer cylinder
32 cylindrical rubber plate
33 slide slot hole
34 reinforcing rib
35 hanging hook
40 mountain-side anchor
41 lateral anchor
42 anchor for ground plate
43 nut
45 mountain-side stay rope
46 mountain-side positioning rope
47 lateral stay rope
48 lateral positioning rope
50 tension member
51 fastening bolt
52 back plate
53 spring
54 fastening nut

Claims

What is claimed is:

1. An uprightly-arranged support structure of a protective fence, the protective fence comprising:

a plurality of supports arranged to stand at intervals, the plurality of supports having respective bottom portions thereof arranged to stand via a ground plate on a slope; and

a protective net spread between the plurality of supports, wherein

the bottom portions of the plurality of supports are arranged to stand so as to be slidable in conjunction with the ground plate in a predetermined direction on the slope.

2. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein a plurality of slide holes are formed through the ground plate so that the ground plate is slidably fixed, through the plurality of slide holes, to a plurality of anchors for ground plate, which are the same in number as the plurality of slide holes.

3. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along an inclination direction of the slope.

4. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along a direction orthogonal to an inclination direction of the slope.

5. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along a direction slant to an inclination direction of the slope.

6. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the plurality of supports and the ground plate are of an assembly type.

7. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the plurality of supports and the ground plate are integrally assembled in advance.

8. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the protective net is mounted between an adjacent pair of the plurality of supports as a span unit.