JP5144551B2 - Protective fence such as rockfall - Google Patents

Description

The present invention relates to a protective fence such as a falling rock that is installed along a road and absorbs impact force such as falling rocks, earth and sand, and avalanche with breaking energy and elongation energy of a rope.

As a means of protecting roads and houses from falling rocks, earth and sand, avalanches, etc. that occur on slopes in mountainous areas, multiple horizontal horizontal ropes are stretched between the columns at intervals, and the stretched horizontal ropes Guard fences are used that have a wire mesh attached to the surface to catch falling rocks, earth and sand, and avalanches.
As shown in the load-elongation curve in FIG. 7, when the load applied to the cable by the falling rock is 1/2 or less of the breaking load, the cable absorbs the falling rock energy (hatched portion). When the above load is applied, the strut is deformed to absorb rock fall energy.

In order to cope with the enormous falling rock energy, protective fences have been proposed in which horizontal ropes are stretched on the valley side and the road side between the terminal columns.
In addition, the anchoring part of the support and the side rope is connected via a shock-absorbing bracket, and the impact caused by the sliding friction resistance between the rope and the shock-absorbing bracket and the plastic deformation of the bracket due to the falling rock falling from the mountain side directly hit the rope Some have been proposed to absorb energy by attenuation.

However, the method of stretching a horizontal rope on each of the valley side and the road side between the terminal columns increases the breaking load of the rope that receives the falling rock, but the energy absorption amount in the rope does not increase greatly, There was a problem that the size of the rope end fittings and end struts could not be increased, and the construction was large and the construction cost was high.
Further, the method of absorbing the collision energy with the buffer metal fitting plastically deforms the buffer metal fitting, so that the rope terminal and the buffer metal fitting are required to have a strength higher than the breaking load of the rope. As the rope stretches (the elongation at break is 7% or less), energy absorption cannot be expected so much, and the shock-absorbing bracket and the rope end are directly subjected to impact energy.

Furthermore, when it is going to raise the absorption amount of impact energy by the elongation of a rope, it is necessary to make the distance between support | pillars long span, for example, 30-60m. However, if the span is long, the falling rock occurrence area increases and the amount of falling rocks increases, so it is necessary to increase the rope strength, and it is inevitable to increase the size of the rope end fittings and supports in accordance with the increase in the rope strength. Furthermore, the structure that absorbs impact energy in the entire protective fence increases the difficulty of partial repair, and increases the repair cost.

JP-A-8-13425

The present invention was devised in order to solve the above-mentioned problems, and the object of the present invention is compact, high energy absorption efficiency such as falling rocks, and strength, function, construction and repair. The purpose is to provide a protective fence such as rockfall that is excellent in terms of surface.
The present invention is used as a protective fence for falling rocks because it can be used to prevent falling rocks and avalanches in addition to preventing falling rocks.

In order to achieve the above-mentioned object, the protective fence for falling rocks of the present invention includes a terminal column that is erected along a portion where sloped rocks, earth and sand, avalanche, etc. should be prevented, and a space between the terminal columns. Multiple intermediate struts standing up and down, mountain-side cables stretched in multiple steps at intervals along the mountain side of the terminal strut and intermediate strut, and elongation at break when the mountain-side cable breaks Road side cable and mountain side cable between the intermediate struts, which have 4-9 times the extension, and are provided with a plurality of road side cables stretched in the vertical direction along the road side of the terminal struts and the intermediate struts It is characterized in that a spacing member is attached to each of these. (Claim 1)

According to the present invention, while extending a plurality of hillside cables with an interval in the vertical direction between the terminal struts and a plurality of intermediate strut ridges erected with an interval therebetween, the elongation at break is Use 4 to 9 times as much cable as the mountain side cable as the road side, and between the terminal struts and multiple intermediate struts erected with a gap between them, and the vertical distance along the mountain side along the road side Since the cable is stretched in multiple steps and connected with a spacing member, the impact energy of the cable hit directly by the falling rock is distributed to other cables via the spacing member, and the mountain side cable breaks the cable. All of the elongation up to rupture, that is, up to the break in the plastic region, can be spent absorbing rockfall energy, and the roadside cable can absorb the remaining rockfall energy after the breakage of the mountainside cable by elongation.
Therefore, rocks (1000kj or less) due to the fall of small pebbles due to storms (100kj or less), rockfalls during typhoons that occur several times a year (500kj or less), earthquakes that occur once every few years, etc. ) And other rockfall forms can be handled with a single unit.

In other words, small mountain rocks (100kj or less) that occur frequently frequently can be handled by the mountain side cable alone, making maintenance-free possible. When large rocks (1000kj or less), mountain-side cables break and road-side cables Exhibits an energy absorption function with plastic deformation.
As described above, the energy absorption capability of the cable itself is high, so that it is possible to exert high performance by using a lightweight member as a terminal fitting or an intermediate support, and the plastic deformation of the member is about once every several years. Since it is a large-scale disaster, normal maintenance and repair can be greatly reduced and the cost can be reduced.

(A) is a front view which shows 1st Example of protection fences, such as a falling rock, by this invention, (b) is a top view. (A) is a front view which shows the connection relation of the terminal support of this invention, and a rope terminal, (b) is a top view. (A) is a front view which shows the connection of an intermediate | middle support | pillar and a cable, (b) is a top view, (c) is a side view. (A) is a front view which shows the connection of a space | interval holding | maintenance material and a cable, (b) is a top view, (c) is a side view. (A)-(d) is a schematic diagram which shows the behavior of the falling rock which collided with the protective fences, such as a falling rock of this invention, and the state change of a protective fence. 2nd Example of protection fences, such as a falling rock of this invention, is shown, (a) is a top view, (b) is a front view. It is a diagram which shows the absorbed energy of the conventional protective fence (The cable which considered the safety factor of the normal cable is used). It is a diagram which shows the absorbed energy of the protection fence (combined use of a normal cable and a cable with a big elongation) of this invention.

Preferably, the roadside cable is slidably held in the middle strut via a cable protector.
According to this, the roadside cable attached to the intermediate strut is slidable in the longitudinal direction, so that one piece of falling rock is reliably transmitted to the entire length of the cable between the terminal struts, and the amount of falling rock energy can be increased.
Furthermore, since the cable protection member is formed of a halved pipe having both ends opened in a trumpet shape, the cable can be prevented from bending when the cable extends to the road side, and smooth cable extension can be obtained.

  It includes a mode in which the mountain-side cable is attached to the intermediate strut by cutting the edge. According to this, when the mountain side cable is damaged, it can be repaired in units of damaged intermediate struts, so that it is particularly effective for damage caused by falling small pebbles or the like (100 kj or less) in a storm.

Preferably, a net is stretched on either the mountain side cable or the road side cable.
According to this, it is possible to prevent small-scale falling rocks and earth and sand, which frequently occur, from passing through the cables stretched up and down and reaching the road. In addition, the plastic deformation of the wire net by falling rocks helps absorb rock falling energy and contributes to the transmission of tension to the upper and lower ropes.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, a is the road side (valley side) and b is the mountain side. Reference numeral 1 denotes a hybrid type high energy absorption type protective fence such as a falling rock according to the present invention, which is installed along the boundary between the road and the mountain side inclined surface.
The protective fence 1 for falling rocks, etc. is constructed such that terminal struts 2 and 2 are erected at both ends along a portion to be received and prevented from falling rocks (sediment, avalanche, etc.) from the slope of the mountain. The intermediate struts 3 are erected at substantially equal intervals, and a plurality of vertically long spacing members 6 are located between the intermediate struts 3 and 3.

On the road side “a” of the terminal columns 2 and 2, a cable 4 </ b> A that is extended to the terminal columns 2 and 2 while being supported by the intermediate column 3 is stretched in multiple stages in the vertical direction. A cable 4 </ b> B that extends less than the cable 4 </ b> A is stretched over the facing mountain side b, and an intermediate portion is held by the intermediate column 3.
Cables 4A and 4B, which are stretched in a plurality of stages on the road side a and the mountain side b of the terminal columns 2 and 2, respectively, are supported by the spacing member 6, and at least the mountain side cable 4B has a wire mesh over the entire surface. 7 is stretched. In the present invention, “cable” is a concept including a rope.

The terminal column 2 may be composed of a single H-shaped steel like a normal column, but in this embodiment, as shown in FIG. Two unit struts 2A and 2A are arranged with a spacing left and right, and two unit struts 2B and 2B are arranged with a spacing to the left and right on the mountain side b. Are integrated by welding or the like, and plate-like connecting members 21 and 21 are respectively passed to the road side surface and mountain side surface of the left and right unit columns, and fixed by welding or the like to form a box-shaped column having a large cross section and high strength. .

In this example, the four unit columns 2A and 2B are made of, for example, an H-shaped steel having a length of 300 mm × 300 mm × 10 mm × 15 mm and a length of 4000 mm, and are galvanized to enhance the anticorrosion effect. Moreover, in order to maintain a landscape, resin coating may be given on galvanization.
The four unit columns 2A and 2B have a required length of, for example, 1000 mm and a lower portion 211 embedded in a cement-based foundation 50 such as mortar or concrete, and are firmly fixed to the ground. Of course, when the ground has a concrete foundation wall like the virtual line of FIG. 1, the lower part 211 is embedded using this. The unit struts 2A and 2B may be square steel pipes instead of H-shaped steels, or may be grooved steels welded to face each other.

The intermediate strut 3 is made of, for example, a 300 mm × 300 mm × 10 mm × 15 mm H-shaped steel having a length of 4150 mm as shown in FIG. For this purpose, it is galvanized. In order to maintain the landscape and further enhance the anticorrosion effect, resin coating may be applied thereon.
The intermediate strut 3 is firmly erected by embedding a lower part 311 having a required length, for example, 1150 mm, in a cement-based foundation 50 such as mortar or concrete.
However, the present invention is not limited to this, and when the ground has a concrete foundation wall as in the case of the terminal column, the lower part 311 may be embedded using this, and a plate with a stay is attached to the lower part. It may be provided upright by being rigidly connected to a plate hardware (not shown) anchored to a cementitious foundation.

FIG. 1 shows a state of connection between the cable 4 and the terminal columns 2 and 2. As shown in FIG. 1B, a plurality of cables 4A are provided between the terminal columns 2 and 2 at both ends on the road side and mountain side of the protective facility. , 4B are stretched up and down at appropriate intervals.
As shown in FIG. 2, the cable 4 </ b> A on the road side a passes through the unit struts 2 </ b> A and 2 </ b> A on the road side of the terminal strut 2 and is fastened to the cable end bracket 11 that is fastened with nuts via the turnbuckle 10. Similarly, the cable 4B on the mountain side is similarly connected via a turnbuckle 10 to a cable end fitting 11 whose ends are fixed to the unit pillars 2B and 2B on the mountain side of the terminal column 2. The initial tension is applied by 10 operations.

The cable 4B stretched on the mountain side is, for example, a cable or rope having a galvanized structure of 7 × 7, a diameter of 16 mm, an elongation at break of 6.5%, a break load of 165 kN, and an absorbed energy of 11 kN · m. . On the other hand, the cable 4A stretched on the road side has a characteristic that the elongation at break is 4 to 9 times that of the mountain side cable 4B.
That is, the road side cable 4A was controlled such that the yield ratio of the constituent wires was 0.5 to 0.7 (yield point / tensile breaking load) and the elongation P was in the range of 25% ≦ P ≦ 60%. It is desirable to use a rope having a large absorbed energy. The reason why the upper limit of elongation is set to 60% is that falling rocks protrude beyond the road more than necessary, and the lower limit of 25% is less than this, resulting in sufficient energy absorption and less effect. Because it is not possible.

A specific example of the roadside cable 4A is a structure of 3 × 7, a diameter of 18 mm, and a material of soft stainless steel (components are C: 0.001% to 0.15%, Si: 0.01% to 1.5%, Mn: 0.3% to 3.0%) , P: 0.05% or less, S: 0.02% or less, Cr: 14.0% to 26.0%, Ni: 6.0% to 22.0%, N: 0.02% or less, the remainder being substantially Fe), the breaking load is 84 kN, elongation Is 52% and the absorbed energy is 35 kN · m.
The cables 4A and 4B may be resin-coated in order to enhance the landscape effect.

FIG. 3 shows the state of support of the road side cable 4A and the mountain side cable 4B with respect to the intermediate column 3. The road side cable 4A is not restrained by the intermediate column 3, and is slidably held via the cable protector 8. Yes. On the other hand, the mountain-side cable 4B is held by the intermediate strut 3 so as not to slide in the longitudinal direction.
First, with respect to the road side cable 4A, two upper and lower holes for inserting the U-shaped bolt 33 through the road side flange 31A of the intermediate column 3 are provided at the left and right sides with the flange 32 interposed therebetween. Is placed along the road side flange 31A so as to be arranged at the center of the upper and lower holes, covered with the protective material 8 in this state, U-shaped bolts 33 are inserted into two holes on the left and right sides, and fastened with nuts.

  The protective material 8 is made of stainless steel, galvanized steel plate, plastic, etc., has a half tubular shape or a track shape, and the inner diameter of the intermediate region is the same as or slightly larger than the diameter of the road side cable 4A. The side cable 4A is inserted. Thus, the road side cable 4A can be slid in the longitudinal direction, and the entire road side cable 4A can be evenly extended, and the rock fall energy absorption efficiency can be increased. A trumpet-shaped enlarged diameter portion 80 is formed at both ends of the protective material 8. This is because, when the road side cable 4A extends and moves to the road side due to falling rocks, stress concentration due to the bending of the cable 4A at the mounting portion of the intermediate column 3 is alleviated and shear fracture is prevented.

Next, the mountain-side cable 4B is attached to the intermediate column 3 by providing a hole through which the U-bolt 33 is inserted in the mountain-side flange 31B in the same manner as the road-side flange 31A described above, and the mountain-side cable 4B is disposed along the mountain-side flange 31B. The cable 4B is directly surrounded by the U-shaped bolt 33 and is pressed by being fastened to the intermediate support 3 with a nut.
In the present invention, the road-side cable 4A is arranged in the upper and lower 10 stages and the mountain-side cable 4B is arranged in the upper and lower 10 stages by the above method. The cable and the protective material may be resin-coated to enhance the landscape effect.

The multi-stage road side cable 4A and the mountain side cable 4B have a spacing member 6 attached between the adjacent middle struts 3 and 3 at a predetermined interval narrower than the spacing of the middle struts. Thus, the multi-stage road-side cable 4A and the mountain-side cable 4B are held such that a predetermined interval is maintained in the vertical direction and a predetermined interval is maintained in the front-rear direction. Accordingly, when some cables that have fallen rocks are displaced toward the road, other cables are also displaced through the spacing member 6.
As shown in FIG. 4, the spacing member 6 has, for example, two H-shaped steels 61, 61 of 100 mm × 100 mm × 6 mm × 8 mm and a length of 3000 mm with a gap between one flange surface, and the other flange surface is a road It is vertically arranged so as to face the side and the mountain side, and several places, for example, about four places in the vertical direction between the opposing flange faces are joined by welding with a connecting member 62, for example, an H-shaped steel of 100 mm × 100 mm × 6 mm × 8 mm. is there.
The cables 4A and 4B are attached to the spacing member 6 by ribbing two upper and lower holes through which the U-bolts 66 are inserted into the flange surfaces 61A and 61B facing the road side a and the mountain side b of the spacing member 6, respectively. The cables 4A and 4B are arranged at the center of the upper and lower holes, and the U-bolts 66 are inserted into the left and right holes and fastened with nuts.

For example, a wire mesh 7 knitted to 50 mm × 50 mm with a galvanized wire diameter of 4.0 mm is attached to the entire surface of at least the mountain side cable 4B with a coupling coil. Preferably, the spacing member 6, the cable 4 </ b> B, and the wire mesh 7 are integrated via a U-bolt so that the spacing member 6, the mountain-side cable 4 </ b> B, and the wire mesh 7 are interlocked when a rock falls. The wire mesh may be stretched also on the road side cable 4A.

FIG. 5 schematically shows a state where a falling rock collides with the falling rock prevention fence of the present embodiment. When the falling rock S collides with the mountain side cable 4B between the intermediate struts 3 and 3 as shown in FIG. 5A, the mountain side cable 4B and the road side cable 4A are separated from each other by the interval holding member 6 as shown in FIG. When the cable is extended to the road side a and the cable is extended by about 6.5%, the mountain side cable 4B is broken as shown in FIG. As shown in FIG. 8, the energy of the one-dot oblique line is absorbed when the mountain side cable 4B is broken.
After breaking the mountain side cable 4B, the falling rock S collides with the road side cable 4A, and the road side cable 4A absorbs energy by stretching as shown in FIG. 5 (d). The amount of energy absorbed when the falling rock stops when the road side cable 4A is extended to 28% is a diagonal line shown in FIG.
In the present invention, the amount of energy absorption of falling rocks increases dramatically due to the elongation of the mountain side cable 4B and the elongation of the road side cable 4A, so that the plastic deformation of the intermediate strut 3 and the terminal strut 2 can be greatly suppressed. Became.

A second embodiment is shown in FIG. This is the protective fence shown in the first embodiment, in which intermediate struts 3 are installed at intervals of 5 m between the terminal struts 2 and 2, and the road side cable 4A is intermediated via the cable protector 8 as in the first embodiment. Although it hold | maintains slidably to the support | pillar 3, about the mountain side cable 4B, the edge is cut | disconnected by each intermediate | middle support | pillar 3.
In other words, a band plate-like bracket 70 is welded to the mountain side flange 31B of the intermediate column 3, and a toyolock terminal 72 processed into an annular shape is provided at the end of the mountain side cable 4B, and the toyolock terminal 72 is shackled to the bracket 70. It is connected through.
In this embodiment, since the mountain-side cable 4B is shortened, the absolute amount of elongation is reduced and the energy absorption amount is reduced, but there is an advantage that repair such as cable replacement is facilitated. Therefore, it is a protective fence suitable for a place where small-scale falling rocks and earth and sand disasters that do not cause breakage of the mountain side cable 4B occur frequently.

The protective fence of the present invention absorbs energy in a form that suppresses elongation by the performance of only the rope when the energy of falling rocks is small within the elastic limit of the mountain side cable 4B, and the energy of falling rocks is large and the plasticity of the mountain side cable 4B. If it becomes a zone, the function of the road side cable 4A also cooperates, and the structure absorbs energy. Even after the mountain side cable 4B breaks, the energy brought in by the high energy absorption performance of the road side cable 4A Can be absorbed. Since the mountain side cable 4B can contribute to energy absorption up to breakage as a sacrificial rope, it can absorb high energy.

And, when receiving normal rockfall, etc., the support members do not undergo plastic deformation, so repair is not necessary, and repair is necessary only when large rockfall energy is received after a typhoon or a big earthquake. There is no maintenance cost.
And by using a rope with high elongation and low breaking load on the road side, the reaction force transmitted to the terminal part when receiving high impact energy is smaller than the conventional fence, so the terminal part of the fence can be made compact Moreover, since the energy absorption capability of the rope itself is high, a lightweight component can be used, the initial cost can be reduced, and the enlargement of the housing can be suppressed. In other words, the performance is improved without increasing the price, and the number of maintenance can be reduced.

The effects of the rock fall energy of the present invention are summarized as follows, and the present invention can deal with disasters caused by these rock fall energy with one type of fence.
1) Minor rockfall energy of about 100 kj: Falling pebbles and rocks due to wind and rain: Frequent occurrence As with conventional fences, it is received by the energy absorbed by wire mesh and mountain side cables. No repair is required because there is no plastic deformation of the fences such as the columns.
2) Slightly large rockfall energy of about 100 to 500 kj: Falling rock mass that occurs continuously during typhoons: several times a year
When the mountain side cable starts plastic deformation, the elongation of the road side cable also begins to contribute to energy absorption. It is an area where energy absorption works due to the energy difference between the mountain side cable, road side cable, and before and after the collision.
3) Large rockfall energy of 500-1000 kj: Falling rock mass generated during a large earthquake: Once a year
When the mountain side cable breaks, energy is absorbed by the extension of the road side cable and the plastic deformation of the column.

2 Terminal column 3 Intermediate column 4A Road side cable 4B Mountain side cable 6 Spacing material 7 Wire mesh 8 Protective material

Claims (5)

Terminal struts erected at intervals along portions where rock fall, earth and sand, avalanches, etc. should be prevented, a plurality of intermediate struts erected at intervals between the terminal struts, and terminals A mountain-side cable stretched in multiple steps at intervals along the mountain side of the column and the intermediate column, and an elongation at break is 4 to 9 times the elongation at break of the mountain-side cable. Characterized in that it is provided with a plurality of road-side cables extending in the vertical direction along the road side of each of the roads, and a spacing member is attached to each of the road-side cable and the mountain-side cable between the intermediate struts. Protected fences such as falling rocks. The protective fence for falling rocks or the like according to claim 1, wherein the roadside cable is supported on the intermediate column through the cable protection material so as to be slidable in the longitudinal direction. The protective fence for falling rocks or the like according to claim 2, wherein the cable protective material is a half pipe with both ends opened in a trumpet shape. The rock fence protection fence according to any one of claims 1 to 3, wherein the mountain-side cable is attached to the intermediate support post. The protective fence for falling rocks according to any one of claims 1 to 4, wherein a net is stretched on one of the mountain side cable and the road side cable.

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