JPH11316141A - Rock-bed rock-falling detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a landslide detecting device capable of measuring a topographic change in the whole area in danger of generation of a landslip or rock- falling by laying an optical fiber netlikely or radially, and affected hardly by lightning current or electric-car overhead line current by using the optical fiber instead of an electric wire. SOLUTION: This device is composed of plural ground surface interlocking part 3 fixed to the ground surface, and an optical fiber 4 passed through inside the interlocking part 3. Displacement of the interlocking part 3 caused by topographic deformation brings variation such as expansion or contraction, distortion and cutting in the connected optical fiber 4. Topographic displacement is detected by measuring variation of light intensity received in a light receiving part 2 due to the variation in the optical fiber 4. When topographic change is generated in a precipice 100 or the like, it is detected immediately to prevent a big disaster or to check it at the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for detecting signs of falling rocks and landslides on roads, railroads, cliffs above residential areas, and the like.

[0002]

2. Description of the Related Art Prior detection of landslides, landslides, falling rocks, etc. is useful for traffic safety and prevention of accidents in residential areas. These may occur suddenly without any notice, but in most cases at least several tens of minutes before, there are many cases where slight changes on the ground surface occur, so these changes have been detected conventionally. Various methods have been implemented.

[0003] Further, when the event occurs on a remote mountain road or railroad, people do not notice the occurrence of the event itself. This is effective in preventing subsequent traffic accidents and the like.

FIG. 9 shows a configuration of a conventional landslide detecting device disclosed in Japanese Patent Application Laid-Open No. 8-43148. The figure shows a case where a landslide of a cliff 14 or an embankment 12 of the railway track 10 is detected. A net fence 8 with a protective net 13 is provided at a place where a landslide is to be detected, such as a cliff 14 near the railway line 10 or an embankment 12 on which the railway line 10 is laid.

In order to prevent landslides and falling rocks, a net fence 8 provided with a protective net 13 is provided in advance, or a protective net 13 is provided directly on the surface of the cliff 14 or the embankment 12. . A sensor is attached to these new or existing protection nets 13, and the presence or absence of a landslide is detected from the vibration of these protection nets 13.

When the protection net 13 has a landslide, a falling rock, or the like, it vibrates due to an impact or a partial breakage. The first sensor cable is used to detect a landslide from this vibration and output a signal. 15 and / or a second sensor cable 16 is attached directly to the protective net 13.

[0007] The first and the second having different sensitivities depending on the strength of vibration.
When the protection net 13 vibrates due to a landslide or other external pressure when the sensor cables 15 and 16 are attached, the first and second sensor cables 15 and 16 detect a signal corresponding to the vibration. When the first and second sensor cables 15 and 16 have outputs equal to or greater than a predetermined value, the arithmetic control unit 21 outputs a signal indicating that a rock has been dropped to the output unit 22 and outputs the signal only to the first sensor cable 15. When there is a signal, a signal determined to be a landslide is output. When only the second sensor cable 16 has an output, a signal determined to be due to artificial contact is output. When there is no output, there is no vibration. Is output. In response to these, a warning of the occurrence of a landslide is issued by the notification device, and displayed on a display device (not shown).

Reference numeral 9 denotes a solar cell for supplying power to the arithmetic control unit 21 and the output unit 22. Next, the sensor cables 15 and 16 in FIG. 9 will be described. FIG. 10 is a sectional view of the sensor cable 15, and FIG.

The first and second sensor cables 15, 1
6, when vibration occurs in the protection net 13, the vibration is transmitted to the first and second sensor cables 15 and 16, and the first and second sensor cables 15, 1 due to the tribo effect.
6, an electric signal is generated, and this signal is sent to the arithmetic and control unit 21.

Of these, the first sensor cable 15 is
As shown in FIG. 10, a core wire 71 is covered with an insulator 72,
It consists of a coaxial cable in which an earth wire 73 is wound around its outer periphery, and the outer periphery thereof is further covered with an outer covering 74.
The sensitivity is set to be high over the entire range from weak shocks to strong shock vibrations. As shown in FIG. 11, the second sensor cable 16 is formed by covering the outer periphery of a first sensor cable 15 made of a coaxial cable with a rubber pipe 19 and further protecting the outer periphery with a stainless steel tube 20. The sensitivity is set so as to be insensitive to the vibration of a weak shock and to be high for the vibration of a medium or strong shock.

The first sensor cable 15 and the second
The sensor cables 16 may be used alone, but by combining two cables in pairs and performing the above-described processing on the circuit, landslides, landslides and rock fall Not only landslides, but also external pressures other than landslides, such as wind, rain, snow, fallen trees, falling rocks, and animals.

A DC voltage is applied to the sensor cables 15 and 16 between the core wire 1 and the ground wire as shown in FIG. Then, due to vibration, impact, or the like of the first sensor cable 15 and / or the second sensor cable 16, a capacitance change between the core wire 71 and the insulator 73 occurs, and the voltmeter 6 causes a voltage change of several mV to several hundred mV. Is detected as

[0013]

Since the conventional landslide detection device is constructed as described above, if the metal fence (metal rope) is expanded, if it is stretched by solar heat or vibrated by the wind, it will not work. There was a problem that it was detected as noise.

Further, for example, since electric wires are installed over a long distance on the ground surface along a train line, a current of the train line (ground current) or a lightning current is detected and a false alarm is generated. was there. The above problem has a fundamental problem in that an electric wire (coaxial cable) is used as a sensor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and measures the topographical change of the entire area where a landslide or a falling rock is likely to occur by installing an optical fiber in a net-like or radial manner. it can. Another object of the present invention is to obtain a landslide detection device that is less affected by a lightning current and a train line current by using an optical fiber without using an electric wire as a sensor.

[0016]

SUMMARY OF THE INVENTION A rock fall detection device according to the present invention comprises an optical fiber whose optical transmission loss changes when it is deformed by an external force, a light emitter provided at one end of the optical fiber, and an optical fiber provided at the other end. The optical deformation sensor includes a photoelectric converter, and a monitoring output circuit that monitors a variation in the output of the photoelectric converter and issues an alarm when the variation exceeds a predetermined value. The use of an optical fiber has an effect of preventing noise from being mixed due to a lightning current or a train current.

Further, a plurality of optical deformation sensors are arranged in a network on the surface of the rock to be monitored, and the outputs of the photoelectric converters of the plurality of optical deformation sensors are monitored. The mesh arrangement has the effect of easily increasing the area to be monitored.

The light deformation sensor has a plurality of optical fibers radially disposed around one light emitting device with one end directed toward one light emitting device, and a photoelectric conversion device provided at the other end of each of the plurality of optical fibers. It consists of a container. The radial arrangement has the effect of reducing the number of light emitting parts.

The present invention has two electrodes provided on one bedrock, means for measuring the resistance between the two electrodes, and resistance monitoring means for monitoring a change in the resistance value. Monitoring the change in resistance has the effect of improving the reliability of detecting rock movement using an optical fiber.

Further, a micro phone installed on the rock, detecting means for detecting a frequency spectrum of an output of the micro phone, and a resistance change detected while the frequency spectrum is within a predetermined range are detected as abnormal changes. It has means for determining that there is.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a rockfall detection device according to a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, an optical fiber 4 having a light emitting portion 1 made of, for example, a light emitting diode or an incandescent light bulb and a light receiving portion 2 made of, for example, a photodiode, and passing through a ground interlocking portion 3 made of resin or a steel tube protection tube is used. Link. The two ends of the optical fiber 4 are installed so as to form a pair of the light emitting section 1 and the light receiving section 2, and in this manner, a portion where there is a possibility of a cliff collapse or a rock fall from the cliff 100 to the road 99 becomes a mesh 90. Installed in Thus, the optical fiber 4 receives the change in which the ground interlocking unit 3 is deformed by the external force, and the light intensity emitted from the light emitting unit 1 is affected, and it is detected that the change has occurred.

It is to be noted that the use of the fact that the transmission loss in the optical fiber changes due to the deformation given to the optical fiber to catch any position change is disclosed in, for example,
No. 258131. The details of the ground interlocking part 3 are shown in FIG. The material strength of the ground interlocking unit 3 is selected according to the landslide degree to be detected. When light landslides are to be detected, the ground interlocking section may be, for example, a soft rubber hose.

Next, the operation will be described. In FIG. 1, light of a constant intensity is emitted from the light emitting section 1. The emitted light reaches the light receiving unit 2 through the optical fiber 4. The light receiving section 2 measures the intensity of the received light. When a moment is applied or deformed due to expansion and contraction or bending of the optical fiber 4, the loss amount of the optical signal changes. Using this characteristic, the movement amount of the ground interlocking unit 3 is measured. The ground interlocking part 3 is fixed to the ground surface. Since the ground interlocking unit 3 is connected to the optical fibers 4, 14, 24, and 34 in four directions, it is monitored by changes in four directions, front, rear, left, and right. The movement change amount can also be measured. The light emitting section 1 and the light receiving section 2 are shown in FIG.
It is good to set at the diagonal position of four sides as shown in FIG.

FIG. 3 is a block diagram showing the structure of the detection circuit.
A scanner circuit 21 for sequentially selecting about 0 points is a monitoring output circuit for comparing a received signal with a standard value stored in advance and outputting an alarm according to the difference. Needless to say, when the area to be monitored is small and only one optical fiber is provided, the scanner circuit 20 can be omitted.

The ground interlocking unit 3 having the light emitting unit 1, the light receiving unit 2, and the optical fiber 4 constitutes a light deformation sensor.
Fixed to the ground.

Embodiment 2 FIG. In FIG. 4, a ground interlocking unit 3 and a light receiving unit 2 are provided radially around a light emitting unit 1 similar to that of FIG. 2 of the first embodiment. The two ends of the optical fiber 4 are installed so as to form a pair of the light-emitting portion 1 and the light-receiving portion 2. In this method, a portion where there is a possibility of a cliff collapse or a falling rock at the cliff 100 or the like is particularly protruded. It is installed radially on 101. As a result, the optical fiber 4 receives the change of the ground interlocking unit 3, and the intensity of the light emitted from the light emitting unit 1 appears, and it is measured how much change has occurred at which point.

Next, the operation will be described. In FIG. 4, light having a constant intensity is emitted from the light emitting section 1. The emitted light passes through the optical fiber 4 and reaches the light receiving unit 2. The light receiving unit 2 measures the intensity of the received light by the method shown in FIG. The amount of movement of the ground interlocking unit 3 is measured using the characteristic that the loss of the optical signal changes when a moment is applied due to expansion and contraction or bending of the optical fiber 4. Since the ground interlocking unit 3 is radially connected, it is monitored by a change in a plurality of directions. Further, the ground interlocking unit 3 can measure the amount of movement change not only in four directions but also in all directions on a plane by combining the four directions.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In FIG. 6, the light emitting unit 1
And an optical fiber 4 passing through a ground interlocking section 3 having a light receiving section 2. The operation and the like are the same as those of the first embodiment. However, in the first embodiment, the light emitting unit and the light receiving unit are provided for each pair. Is provided. As a result, it is not possible to know which part of the bedrock has started to move in order,
It is possible to detect the start of movement of the bedrock itself, and it is possible to significantly reduce costs by reducing the number of the light emitting unit 1, the light receiving unit 2, the scanner circuit 20, the monitoring output circuit 21 and the like. The ground interlocking section 3 may be arranged not only vertically and horizontally as shown in FIG. 6 but also as shown in FIG. 7 for the projection 101 shown in FIG.

Embodiment 4 It is considered that one of the causes of the rock falling from the rock is that the water that has infiltrated into the rock 30 repeatedly freezes over a long time and the cracks 31 of the rock become large as shown in FIG. In order to detect the size of the crack 31 in the rock 30, electric terminals 32 and 33 are embedded on both sides of the crack 31 in the rock 30, and the current I
To measure the change in the resistance value of the rock. Thus, it is possible to detect a minute movement of the rock before detecting the movement of the rock between the two terminals by using the optical fiber, and to take measures in advance.

When this method is used in combination with the first embodiment, it is possible to continuously detect a small movement to a large movement of the rock, so that the accuracy of rock fall detection is improved. However, in the above method, since it is conceivable that not only cracks in the rock but also changes in resistance due to rainfall and the like may occur, the microphone 36 is embedded near the cracks 31, and the frequency spectrum of the detected sound is analyzed by the voice analysis device 22. Only when the frequency spectrum coincides with the frequency spectrum generated at the time of cracking, it is better to judge that cracking has occurred and to judge it together with the measurement result of the current I.

[0031]

As described above, the present invention is constructed so that the electric wire is not used as a sensor. Therefore, even if the electric wire is installed along the electric line, the electric current of the electric line is increased or the lightning current is detected. The effect that there is not is obtained.

Further, noise is not generated by the sun rays or wind.

Also, since it is used in combination with a means for measuring rock resistance, the reliability of the measurement is high.

Further, since the sound of the rock is detected and the means for monitoring the sound is used in combination, the reliability of the measurement is high.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a rock rock fall detection device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a block diagram of a detection circuit of FIG. 1;

FIG. 4 is an overall configuration diagram of a rockfall detection device according to a second embodiment of the present invention.

FIG. 5 is a partially enlarged view of FIG. 4;

FIG. 6 is a diagram showing a detector portion of a rock fall detection device according to Embodiment 3 of the present invention.

FIG. 7 is another example of the detector of FIG. 6;

FIG. 8 is an overall configuration diagram according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a conventional landslide detection device.

10 is a structural explanatory view of the sensor cable 15 of FIG.

11 is a structural explanatory view of the sensor cable 16 of FIG.

12 is an explanatory view of the operation principle of the sensor cable of FIG. 9;

[Explanation of symbols]

1 light emitting section, 2 light receiving section,
3, 13, 23, 33 Ground interlocking part, 4, 14, 2
4, 34 optical fibers, 20 scanner circuits,
21 monitoring output circuit, 30 bedrock,
32, 33 Terminal embedded in rock, A
Ammeter, 36 microphones, 3
7 sound breaking device, 90 rope arrangement,
99 roads, 100 cliffs,

Claims (5)

[Claims] 1. An optical deformation sensor comprising an optical fiber whose optical transmission loss changes when deformed by an external force, a light emitting device provided at one end of the optical fiber, and a photoelectric converter provided at the other end. A rock mass comprising a sensor fixed to a rock mass or the like to be monitored, a monitor output circuit for monitoring a variation in the output of the photoelectric converter, and issuing an alarm when the variation exceeds a predetermined value. Rockfall detection device. 2. The method according to claim 1, wherein a plurality of optical deformation sensors are arranged in a network on the surface of the rock to be monitored, and outputs of photoelectric converters of the plurality of optical deformation sensors are monitored.
Rock rock fall detection device according to any one of the above. 3. The optical deformation sensor according to claim 1, wherein one end of the optical fiber is directed toward one light emitting device, and a plurality of optical fibers radially arranged around the light emitting device, and a photoelectric conversion device provided at the other end of each of the plurality of optical fibers. The rock fall detection device according to claim 1, comprising a vessel. 4. A combination of two electrodes provided on one bedrock, a means for measuring a resistance between the two electrodes, and a resistance monitoring means for monitoring a change in the resistance value. The rock fall detection device according to claim 2. 5. A micro phone installed on a bedrock, detecting means for detecting a frequency spectrum of an output of the micro phone, and a resistance change detected while the frequency spectrum is within a predetermined range is detected as an abnormal change. The rock fall detection device according to claim 4, further comprising means for determining that there is a rockfall.