JPH073295Y2 - Displacement detection structure of slope failure detector - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting collapse of a slope using a change in transmission loss of an optical fiber cable, and more particularly to a displacement detecting structure thereof.

[0002]

2. Description of the Related Art Mountain roads that pass through mountainous areas have more steep slopes on both sides of roads than plain roads, and slope failures such as landslides caused by rainfall and rockfall and sand outflow due to earthquakes are likely to occur. In addition, the mountainous roads have many curves, so the visibility is poor, and even if a slope collapse occurs, it is difficult to find it visually. For this reason, various detection devices are used for the purpose of catching a slope failure on a mountain road in advance. Conventionally, as a detection device of this type, a slope movement amount measuring device that presets a position where danger is expected and directly measures the movement amount of the slope surface, or a slope measuring device that measures the slope change of the slope surface. A method of installing a collapse detection sensor is often used. However, since the detection range of the sensor is limited, a large number of dedicated lines to the detection device and the monitoring station are required to detect a change over a wide range, which causes problems in terms of cost and long-term maintenance. Therefore, as an alternative to the above, there has been proposed a device that uses a pile, a girder, and an optical fiber cable, and that detects the collapse of a slope by utilizing the fact that the transmission loss of the optical fiber cable changes when subjected to shearing force (Patent Application In 1990, No. 194022), the initial purpose was met for the time being.
However, in terms of maintenance, structural problems remain in the mechanism for detecting displacement, such as how to mount the girder and the mechanism for holding the optical fiber cable.

[0003]

[Problems to be solved by the invention]
An object of the present invention is to provide a displacement detection structure in which a girder and a method of mounting a girder and an optical fiber cable in a slope failure detection device using an optical fiber cable are improved so that problems do not occur in maintenance for a long time.

[0004]

According to the present invention, a plurality of piles standing in a row on a slope, and a girder and an optical fiber cable laid along the plurality of piles away from the ground are used. When a relative displacement occurs between the pile and the girder due to the movement of the slope of the section, the optical fiber cable is deformed by bending, and the change in transmission loss due to this deformation is measured to prevent the occurrence of slope collapse. An optical fiber cable mounting structure in a slope failure detecting device for detecting,
A protrusion row consisting of at least two pairs in the vertical direction attached to each of the pile and the girder is normally sandwiched between the optical fiber cables at at least two locations, and when the relative displacement occurs, the projection rows are arranged at one of the two locations. Displacement detection structure for a slope failure detection device, characterized in that the optical fiber cable is provided at a position where it is deformed by bending.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a displacement detecting structure of a slope failure detecting device according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of the present invention. A large number of piles 1 are set up at a place where slope collapse is expected, and a girder 2 is provided so as to straddle some piles and be slightly separated from the piles. ing. This girder is fixed by a pile (not shown). And the optical fiber cable 3 provided along this girder
Is lightly sandwiched between two protrusions 4a of the mounting bracket 4 partially fixed to the pile 1 and partially fixed to the girder 2, in two places,
When the distance between the pile 1 and the girder 2 changes, the pile 1 and the girder 2 are held so as to be compressed at one of them. The detection light beam enters from one end and exits from the other end. The intensity of the emitted light is attenuated by the icrobending loss when the optical fiber cable 3 is compressed. In such a configuration, when the slope collapse occurs and the relative position of the pile 1 and the girder 2 changes, the optical fiber cable sandwiched between the upper and lower projections is compressed and the intensity of the emitted light changes. That is, it is detected that a part of the slope has collapsed.

2A and 2B are views specifically showing the structure of the mounting member 4. FIG. 2A is a top view and FIG. 2B is a front view. Two upper protrusions 6 are attached to the pile-side metal plate 5 attached to the pile 1, and two lower protrusions 8 are attached to the pile-side metal plate 7 attached to the girder 2. The optical fiber cable 3 is sandwiched between the protrusions 6 and 8 at two points. In Figure 3, the pile 1 moves to the girder 2 side and the protrusions 6 and 8 of the metal fitting 4 are shown.
The distance between the two becomes narrower than in Fig. 1 and the optical fiber cable 3
FIG. 9 is a diagram showing a state where compression is being applied at the position indicated by 9; And since the emitted light 10 changes due to this compression,
It can be detected that a part of the slope has collapsed. 1
The number of protrusions in the set is not limited to two, and it is essential only that the optical fiber cable be compressed in one place even if the pile and the girder come close to or apart from each other. . Further, since it is difficult to set the distance between the pile and the girder to a predetermined distance, although not shown in FIG. 1, for example, the thickness is relatively adjusted between the pile 2 and the pile-side metal plate 5 in FIG. If the spacers that can be attached are attached, the accuracy of pile driving can be relatively small.

[0007]

As is apparent from the above description, according to the present invention, by using an optical fiber cable holding device having a simple structure between the pile and the girder, no matter how the pile is displaced, It is possible to reliably detect that there is a displacement.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a configuration of an embodiment of the present invention.

FIG. 2 is a view showing a displacement detecting structure according to the present invention.

FIG. 3 is a diagram showing a state in which the mounting bracket is deformed and the optical fiber cable is compressed.

[Explanation of symbols]

 1 Pile 2 Girder 3 Optical fiber cable 4 Mounting bracket 4a Protrusion 5 Pile side metal plate 6 Upper protrusion 7 Girder side metal plate 8 Lower protrusion 10 Emitted light

Claims (1)

[Scope of utility model registration request] 1. A plurality of piles standing in a row on a slope, and a girder and an optical fiber cable laid along the plurality of piles apart from the ground are used, and the piles and the girders are partially moved by moving the slope. When a relative displacement occurs between the optical fiber cable and the optical fiber cable, the optical fiber cable is deformed by bending, and the change in transmission loss due to this deformation is measured to detect the occurrence of slope failure. Which has a structure, and in which the above-mentioned optical fiber cable is normally sandwiched in at least two places and the relative displacement occurs when the projection row consisting of at least two pairs in the vertical direction attached to each of the pile and the girder, A displacement detecting structure for a slope failure detecting device, characterized in that the optical fiber cable is set at such a position as to cause deformation by bending.