JP6241921B2 - Avalanche prevention fence installation method - Google Patents

Description

  The present invention relates to a technique for preventing an avalanche. More particularly, the present invention relates to a method for installing an avalanche prevention fence.

In order to prevent avalanches, various avalanche prevention fences have been conventionally proposed.
4 and 5 show an example of a conventional avalanche prevention fence. 4 and 5, reference numeral 1 indicates a slope, and reference numeral R indicates a road (road surface).
The conventional avalanche prevention fence 10 illustrated in FIGS. 4 and 5 includes three pile members 11 and a plurality of crosspiece members 12.
The direction along the vertical direction (slope) of the slope 1 is at a predetermined pitch P (see FIG. 5), and the lateral direction (horizontal direction) is a gap W between adjacent avalanche prevention fences 10 (FIG. 4). A plurality of avalanche prevention fences 10 are arranged with reference to each other.

However, in the conventional avalanche prevention fence shown in FIGS. 4 and 5, the snow cover 20 on the natural ground (slope) 1 is divided by the avalanche prevention fence 10 (region L <b> 2 in FIG. 5). Therefore, compared with the case where the avalanche prevention fence 10 is not provided (the snow cover covers the natural mountain 1 at a constant depth: not shown), the area where the snow cover 20 contacts the natural mountain (slope) 1. (Grounding area: the area of the region indicated by L1 in FIG. 5) decreases.
Further, when the frictional force between the snow cover 20 and the ground 1 is reduced, the force for supporting the snow cover 20 is reduced, and the possibility of an avalanche is increased.

In the conventional avalanche prevention fence shown in FIGS. 4 and 5, when a large amount of fresh snow falls in a short time, as shown in FIG. 6, the dry snow surface avalanche becomes a horizontal beam member 12 of the avalanche prevention fence 10. It slips down and flows down (dry snow surface avalanche slips). And it covers the snow cover 20 accumulated in the area below the avalanche prevention fence 10 and causes the snow collapse in the area, which may induce a full-scale avalanche from the bottom of the lowermost fence.
In order to prevent the dry snow surface avalanche from slipping through, as shown in FIG. 7, measures are taken to stretch a steel mesh 13 on the avalanche prevention fence 10.

However, if the fine mesh 13 is stretched, the mesh will make all the small-scale sloughs (point generation surface avalanches) thin, so that snow accumulates in a short time, exceeding the snow accumulation capacity of the avalanche prevention fence 10. There is a problem that it will.
In addition, the current situation is that the avalanche from the bottom of the lowermost fence is dealt with by removing snow with human power and heavy machinery.

Furthermore, for example, as shown in FIG. 5, a bowl-shaped snow mass (so-called “dripping”) 21 is formed on the upper part of the avalanche prevention fence 10. If the saddle-shaped snow mass (so-called “rolling”) 21 collapses, there is a risk of causing an avalanche. The sag 21 is a burden on the manager at the road maintenance site. And that the height dimension of the avalanche prevention fence 10 is higher than necessary may promote the development of the drooping 21.
The conventional avalanche prevention fence 10 is not disclosed to suppress the formation of the sag 21 and does not disclose that the sag 21 collapses and causes an avalanche.

Further, as shown in FIG. 5, the conventional avalanche prevention fence 10 divides the snow cover 20 on the natural ground (slope) 1, so that an area where the snow slides down and the ground surface is exposed is generated (reference numeral in FIG. 5). L2).
In the area L2 where the conventional avalanche prevention fence 10 acts like a fence and the snow is not piled up and the ground surface is exposed, the heat insulation effect due to snow accumulation is lost, so that the frost heave in the area L2 (the ground inside freezes and the ground surface becomes This may cause a problem (rising phenomenon).

As another conventional technique, for example, a technique has been proposed in which a glide suppression fence is installed above an avalanche prevention fence to reduce the load of snow that the avalanche prevention fence loads (see Patent Document 1).
However, even in the related art (Patent Document 1), when the amount of snow accumulation exceeds a certain limit, the snow accumulation capacity is exceeded and the avalanche occurs beyond the avalanche prevention fence.

JP2013-104214A

  The present invention has been proposed in view of the above-described problems of the prior art, and can maintain a constant contact area of the snow cover, thereby preventing a situation where the snow cover exceeds the snow accumulation capacity. The purpose is to provide an avalanche prevention fence installation method.

The avalanche prevention fence installation method of this invention installs a plurality of avalanche prevention fences (10) on a plurality of steps in the vertical direction of the slope (1) to prevent an avalanche,
Each of the avalanche prevention fence (10) includes a pile member (11) and a plurality of crosspiece members (12) extending linearly,
The avalanche prevention fence (10) provided with a plurality of crosspiece members (12) extending in a straight line is arranged to be inclined with respect to the horizontal direction,
Slope (1) An avalanche prevention fence (10 below the slope) on the extension lines (Lc1, Lc2) of the avalanche prevention fence (10) provided with a plurality of crosspiece members (12) extending linearly above the slope (1). ) Is inclined in the opposite direction to the upper avalanche prevention fence (10), and the avalanche prevention fence (10) below the slope (1) has a plurality of straight lines extending above the slope (1). The avalanche prevention fence (10) provided with the horizontal beam member (12) is arranged to be inclined at a predetermined angle with respect to the inclined extension line (Lc) .
Here, the “predetermined angle” is set on a case-by-case basis according to conditions such as the angle of the slope (1), the interval between the avalanche prevention fences (10) to be installed, and the expected snowfall. This is because the snow sliding force changes depending on these conditions.
In addition, the “predetermined angle” is not limited to a certain angle, but includes a case where each avalanche prevention fence (10) is different (including a case where it is randomly changed).

In the present invention, it is possible to horizontally arrange the avalanche prevention fence (10B) at the bottom of the slope (1) (near the road R). In that case, the avalanche prevention fence (10) excluding the avalanche prevention fence (10B) at the bottom of the slope (1) (near the road R) is set at a predetermined angle with respect to the horizontal direction (the direction of arrow H in FIG. 1). It is inclined (at an inclination angle θ).
Alternatively, the avalanche prevention fence (10B) arranged horizontally may be omitted.

According to the present invention having the above-described configuration, the snow accumulated on the entire slope becomes uniform, and the snow can be distributed to a place where the snow below the avalanche prevention fence (10) is difficult to accumulate. And by the inclination of the avalanche prevention fence (10), it is easy to generate a small avalanche above the avalanche prevention fence (10), and it can suppress that the amount of snow accumulation exceeds. Furthermore, since the avalanche prevention fence (10) is inclined, it is easy for snow to move to the area below the avalanche prevention fence (10) and to accumulate snow.
In the present invention, since the avalanche prevention fence (10) is inclined (at an inclination angle θ) with respect to the horizontal direction (in the direction of arrow H in FIG. 1), the avalanche prevention fence (10) is above the slope (1). The accumulated snow (20) is not blocked by the avalanche prevention fence (10), and moves obliquely downward along the avalanche prevention fence (10).
Therefore, the snow (20) accumulated above the slope (1) of the avalanche prevention fence (10) is always kept in contact with the ground (slope 1), and the snow (20) The speed of movement decreases, and the possibility of avalanches due to some snow collapses decreases.
In other words, the avalanche prevention fence (10) below the slope (lower) is arranged at a predetermined angle with respect to the inclined extension line (Lc) of the avalanche prevention fence (10) above the slope (upper). As a result, the area where the snow is in contact with the ground increases, reducing the possibility of avalanches. The same applies to the case where the “predetermined angle” is not a fixed angle but is different for each avalanche prevention fence (10) (including a case where it is randomly changed).

And since the snow (20) accumulated above the slope (1) of the avalanche prevention fence (10) moves diagonally downward along the avalanche prevention fence (10), a mesh ( Even if measures are taken to prevent slipping of dry snow by placing a wire mesh), the accumulated snow (20) moves obliquely downward, so the avalanche prevention fence (10) does not apply all the load of the accumulated snow. Therefore, the snow accumulation capacity is not exceeded.
Furthermore, according to the present invention, since the snow (20) is maintained in a grounded state, frost heave in the region below the avalanche prevention fence (10) is prevented.

Here, since the avalanche prevention fence (10) below the natural ground is arranged at a predetermined angle with respect to the inclined extension line (Lc) of the upper avalanche prevention fence (10), The snow that has moved obliquely downward along the avalanche prevention fence (10) abuts on the next-stage avalanche prevention fence (10), moves forward at a predetermined angle, and further downwards. Move toward the avalanche prevention fence (10).
As a result, the snow (20) accumulated above the slope of the (above) avalanche prevention fence (10) is bent down (in a downward direction) while turning to a zigzag at a predetermined angle. Proceed with C). Since the avalanche prevention fence (10) does not block the folded path (path C where the snow travels), the snow (20) is always maintained in a state where the area below it is grounded.

Moreover, the snow (20) accumulated above the slope of the avalanche prevention fence (10) faces the avalanche prevention fence (10) below the slope and is folded while turning to a zigzag at a predetermined angle by the avalanche prevention fence. Since the curve (C) travels in a curved manner, the path (C) along which the snow (20) travels is longer than the path when the avalanche occurs due to the collapse (snow travels in a straight line below the slope). Then, every time the avalanche prevention fence (10) rolls in a zigzag with a predetermined angle, the moving speed of the snow becomes slow.
Therefore, according to the present invention, it takes a long time for the snow (20) to reach the area below the slope (for example, the road R). Therefore, it takes a long time for snow to ride on the road below the slope and hinder traffic. If the snow stops and snow can be removed in the meantime, the traffic will be hindered by the snow descending the slope. To be prevented.

It is a front view which shows embodiment of this invention. It is a side view which shows embodiment of this invention. It is a front view which shows the modification of embodiment of this invention. It is a front view which shows arrangement | positioning of the avalanche prevention fence in a prior art. It is a side view which shows arrangement | positioning of the avalanche prevention fence in a prior art. It is a side view explaining the case where fresh snow passes through the avalanche prevention fence in a prior art. It is a mode figure explaining the case where a mesh is provided in the avalanche prevention fence of fresh snow in a prior art.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG.1 and FIG.2, the avalanche prevention fence 10 (10B) is divided into four steps shown by code | symbol ST1-ST4 from the upper side of the slope 1 on the slope 1 which exists above the road R. FIG. .

The avalanche prevention fence 10 in the uppermost stage ST1 to the third stage ST3 is arranged to be inclined downward by a predetermined angle θ with respect to the horizontal direction (reference numeral H direction in FIG. 1: lateral direction).
Here, the predetermined angle θ is preferably in the range of 15 ° to 45 °, for example. However, the inclination angle θ is greatly affected by the inclination angle of the slope 1 and the amount of snow in the avalanche prevention fence (proportional to the amount of snowfall). In that sense, the inclination angle θ of the avalanche prevention fence 10 with respect to the horizontal direction may be less than 15 ° or may be greater than 45 °.
Here, the inclination angle θ of the avalanche prevention fence 10 is not limited to a fixed angle, and the case where the inclination angle θ is different for each avalanche prevention fence 10 (including the case where the inclination angle θ is randomly changed). Includes. For example, the inclination angle θ of the avalanche prevention fence 10 in the uppermost stage ST1 is 45 °, the inclination angle θ of the avalanche prevention fence 10 in the second stage ST2 is 30 °, and the inclination angle θ of the avalanche prevention fence 10 in the third stage ST3 is 20 Sometimes set to °. Alternatively, the inclination angle θ of the avalanche prevention fence 10 in the uppermost stage ST1 is 20 °, the inclination angle θ of the avalanche prevention fence 10 in the second stage ST2 is 30 °, and the inclination angle θ of the avalanche prevention fence 10 in the third stage ST3 is 45. It can also be set to °.
The speed at which the snow moves can be adjusted by appropriately setting the inclination angle θ.

The predetermined angle θ can be calculated using the weight of snow acting on the avalanche prevention fence 10, the frictional force of snow moving on the mountain side (upward) of the avalanche prevention fence 10, and the like.
However, the inclination angle θ of the avalanche prevention fence 10 varies depending on the installation interval of the avalanche prevention fence 10, the design snow depth, and the inclination angle α of the slope 1.

The avalanche prevention fence 10 in the second stage ST2 is provided at a position that makes a predetermined angle with respect to an extension line Lc1 (virtual line) extending downward from the slope of the avalanche prevention fence 10 in the uppermost stage ST1. The “predetermined angle” is 90 ° in FIGS. 1 and 2, but, similarly to the inclination angle θ described above, the weight of snow acting on the avalanche prevention fence 10, ) Varies depending on the frictional force of the snow moving, the installation interval of the avalanche prevention fence 10, the design snow depth, and the inclination angle α of the slope 1.
Further, the “predetermined angle” (an angle formed by the avalanche prevention fence 10 below the slope relative to the extension line Lc1 below the slope of the avalanche prevention fence 10 above the slope) is 90 in FIGS. It is also possible to set the “predetermined angle” to be different for each avalanche prevention fence 10 (the “predetermined angle” is randomly changed) although it is constant in degrees.
Further, the avalanche prevention fence 10 of the third stage ST3 is disposed at a position that makes a predetermined angle with the extension line Lc2 extending downward from the slope of the avalanche prevention fence 10 of the second stage ST2.
Here, regarding the position of the slope 1 in the horizontal direction (reference sign H direction: horizontal direction in FIG. 1), the arrangement (arrangement) of the avalanche prevention fence 10 in the third stage ST1 is the same as that of the avalanche prevention fence 10 in the uppermost stage ST1. Similar to the arrangement (array).

According to the embodiment shown in FIGS. 1 and 2, the avalanche prevention fence 10 is inclined at an inclination angle θ with respect to the horizontal direction (direction H in FIG. 1). The snow 20 (see FIG. 2) accumulated in the snow does not stay in this manner by the avalanche prevention fence 10.
The snow 20 accumulated above the slope of the avalanche prevention fence 10 is not blocked by the avalanche prevention fence 10 and can move obliquely downward along the avalanche prevention fence 10. In other words, in the illustrated embodiment, the avalanche prevention fence 10 that is inclined with respect to the horizontal direction (the direction indicated by reference sign H in FIG. 1) has an action of guiding the snow cover 20 above it to move obliquely downward. Play.
Therefore, the avalanche prevention fence 10 does not apply all the load of the snow 20 accumulated above it, and it is prevented that the snow accumulation capacity is exceeded.
Even when the avalanche prevention fence 10 is stretched with a mesh to prevent dry snow from slipping through, the accumulated snow 20 is guided diagonally below the avalanche prevention fence 10, so It wo n’t be over.

As described above, the next-stage avalanche prevention fence 10 is positioned so as to form a predetermined angle with the extension line of the upper avalanche prevention fence 10. In FIG. 4, the avalanche prevention fence 10 of the second stage ST2 is arranged so as to make a predetermined angle with the extension line Lc1 of the uppermost stage ST1, and the extension line Lc2 of the second stage ST2 makes a predetermined angle. The third level ST3 avalanche prevention fence 10 is arranged.
Therefore, the snow cover 20 (see FIG. 2) that has moved obliquely downward along the upper avalanche prevention fence 10 is disposed so as to form a predetermined angle with an extension line (virtual line) of the upper avalanche prevention fence 10. It contacts the avalanche prevention fence 10 in the next stage. And in the avalanche prevention fence 10 of the contact | abutted step | paragraph, the advancing direction of the snow cover 20 makes a predetermined angle, and moves to a zigzag, and moves to the extension line (virtual line) direction of the said avalanche prevention fence 10 of the said next stage. .
Then, the snow cover 20 whose traveling direction has been rolled at a predetermined angle further proceeds obliquely downward.

That is, the snow accumulation 20 accumulated above the slope of the avalanche prevention fence 10 travels along a bent path (reference numeral C in FIG. 1) while moving downward and zigzag at a predetermined angle. . Since the avalanche prevention fence 10 does not block the bent path (the path C on which the snow travels), the traveling snow cover 20 is always maintained in a state where the area below it is in contact with the ground.
Since the snow cover 20 is maintained in a grounded state, a resistance force acts between the moving snow cover 20 and the natural ground (slope) 1 to reduce the speed at which the snow cover 20 moves.
And since the snow cover 20 is maintained in the state where it grounded, the possibility that a part of the snow cover 20 collapses and causes an avalanche is reduced.

Here, the path “C” along which the snow accumulation 20 accumulated above the slope of the avalanche prevention fence 10 travels, that is, the avalanche prevention fence 10 below the slope, is zigzag at a predetermined angle with the avalanche prevention fence 10. The path “C” that travels while being bent while rolling is longer than the path when the avalanche occurs due to the collapse (the path in which the snow cover 20 moves in a straight line below the slope). And every time the avalanche prevention fence 10 rolls by a predetermined angle, a moving speed becomes slow.
Therefore, according to the illustrated embodiment, the time spent for the snow cover 20 to reach the area below the slope (downward in FIG. 1) (for example, the road R) becomes longer. Therefore, it takes a long time for the snow cover 20 to get on the road below the slope and block the traffic. If the snow stops and the snow can be removed during that time, the traffic is blocked by the snow falling on the slope 1. Is prevented in advance.
Even if the snow cover 20 that has been moved in a zigzag with a predetermined angle gets on the road R, the traveling speed is slow, so a large amount of snow does not run on the road R at a time. And the time for removing the snow on the road R can be secured.

Here, the avalanche prevention fence 10 does not exist on the straight line indicated by “D” in FIG. 1 (straight line from the upper side of the slope 1 to the lower side).
However, in FIG. 1, the avalanche prevention fence 10 is provided so that the snow moves along the path C. Therefore, even if the avalanche prevention fence 10 is not provided on the straight line “D”, the avalanche prevention fence 10 is provided on the straight line “D”. Snow is prevented from collapsing along.

When the avalanche prevention fence 10 is small, the width (width in the direction of arrow H in FIG. 1) in the area where the avalanche prevention fence 10 does not exist like the straight line indicated by “D” in FIG. There is a risk of snow falling in the direction from the top of the slope 1 to the bottom (in the region indicated by the straight line D).
On the other hand, if the number of avalanche prevention fences 10 is increased, the width of the area where the avalanche prevention fences 10 do not exist (area indicated by the straight line D) is reduced in the direction from the upper side of the slope 1 to the lower side. The likelihood of a collapse will decrease. However, if many avalanche prevention fences 10 are installed, the introduction cost increases.
The installation interval of the avalanche prevention fence 10 can be determined based on the amount of snowfall and the snow fall prevention efficiency in the direction from the upper side of the slope 1 to the lower side.
According to the illustrated embodiment, the snow cover 20 moves along the extension line of the avalanche prevention fence 10 to the area where the avalanche prevention fence 10 does not exist (the area indicated by the straight line D) in the direction from the upper side to the lower side of the slope 1. Therefore, even if the snow collapses in the region indicated by the straight line D, the avalanche is prevented from occurring due to the movement of the snow cover 20.

  In addition, the avalanche prevention fence 10B (lowermost stage) below the slope 1 (downward in FIG. 1) is installed in the horizontal direction (indicated by reference sign H in FIG. 1). This is because it is necessary to prevent the snow cover 20 from riding on the road R.

In the embodiment shown in FIG. 1, all the flow prevention fences 10 are inclined, but as shown in FIG. 3, the avalanche prevention fences in the region closest to the road R on the slope 1 (the fourth stage in FIG. 3). 10B can be arranged horizontally (or parallel to the road R). The avalanche prevention fences 10B adjacent to each other are arranged with an interval W (predetermined interval).
This is to prevent the snow moving from above to below by the avalanche prevention fence 10 from riding on the road R.
Here, the predetermined interval W is set on a case-by-case basis by the arrangement relationship between the uppermost stage and the second stage and the arrangement of the second and third stages.

  It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Slope 10 ... Avalanche prevention fence 20 ... Snow R ... Road

Claims (1)

A plurality of stages in the vertical direction of the slope to prevent avalanche (1) to install a plurality of avalanche prevention fence (10),
Each of the avalanche prevention fence (10) includes a pile member (11) and a plurality of crosspiece members (12) extending linearly,
The avalanche prevention fence (10) provided with a plurality of crosspiece members (12) extending in a straight line is arranged to be inclined with respect to the horizontal direction ,
Slope (1) extension line of the avalanche prevention fence having a plurality of transverse beam member extending above the linearly (12) (10) (Lc1, Lc2) Homen lower avalanche prevention fence on (10 ) above the avalanche preventing fence (10) and inclined in opposite directions are arranged, the slope face (1) below the avalanche preventing fence (10) is slope (1) a plurality of upwardly extending straight avalanche prevention fence installation method characterized that you disposed inclined at a predetermined angle with respect to the inclined extension of the avalanche prevention fence having horizontal crosspiece member of (12) (10) (Lc ).

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