JPH11304550A - System for detecting avalanche of sand and stone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the occurrence position, moving position and speed of an avalanche of sand and stone in a system for detecting the avalanche of sand and stone in a river. SOLUTION: Support legs 2 are fixed to the bed 11 of a river 10 to support steel pipes 1 which are located in water along the river width and disposed with specified spacings from the upstream to the downstream, and AE sensors 3 are disposed in the steel pipe 1 to send signals from the AE sensors 3 to detectors 20 through cables. When the avalanche of sand and stone occurs, the water flow increases with solids in water, colliding against the steel pipes 1 to generate ultrasonic waves which the AE sensors 3 sense to provide signals and processors in the detectors 20 judge from the heights of the detected signal levels that these signals indicate a safe condition, a sign or occurrence of the avalanche of sand and stone. Its position and speed can be detected from the signal detect conditions by the plurality of AE sensors disposed from the upstream to the downstream.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AE-type debris flow detection system, and more particularly to an AE-type debris flow detection system capable of easily detecting generation of a debris flow, its position and speed.

[0002]

2. Description of the Related Art In a conventional river debris flow detection system, for example, although not shown, a light emitter and a light receiver are provided so as to face each other along a river where a debris flow is likely to occur, and light is received from the light emitter. When the infrared signal to the vessel is continuously interrupted for a predetermined time or more, it is considered that debris flow has occurred, and a warning is issued. Further, there has been proposed a device which, when detecting that the depth of a riverbed has become shallower than a predetermined value, judges that the river is in a dangerous state and issues an alarm.

A typical system for detecting debris flow using a wire or the like will be described with reference to FIG. In FIG.
A plurality of wires 51 are installed near the water surface of the river A, such as a mountain stream where there is a risk of occurrence of debris flow, so as to cross the flow of the river A at arbitrary intervals from the upstream to the downstream.
Each wire 51 is connected in series by an electric wire 52, and both ends of the series connection are connected to a disconnection monitor 53. If any wire 51 is cut by the debris when the debris flow occurs, the resistance value of the series connection increases or the current stops flowing, so the disconnection monitor 53
Detects the occurrence of debris flow.

[0004]

In the above-mentioned conventional debris flow detection system, the method using light cannot instantaneously detect the occurrence of debris flow in a river, but requires a long time from actual debris flow generation to detection. In short, there is a problem in reliability because light incidence is detected, and the system configuration is complicated, and installation work is difficult. In the method using the wire shown in FIG. 6, generation of debris flow is turned ON / OF.
Just knowing from F, the debris flow cannot be detected at an early stage, and its scale, speed, etc. cannot be detected, and the occurrence status cannot be continuously monitored.

Therefore, in the present invention, the debris flow moving from the upstream to the downstream of the river is detected, and the debris flow generation location, moving position and speed can be easily detected and determined with a simple configuration.
An object of the present invention is to provide an E-type debris flow detection system.

[0006]

The present invention provides the following means for solving the above-mentioned problems.

[0007] A plurality of steel pipes buried in the water of the river and stretched in the width direction of the river and fixed to the riverbed at predetermined intervals from each other, an AE sensor mounted in the steel pipe, and the AE sensors detected by the AE sensors. A detection device which receives a signal of a sound emitted from the steel pipe and determines a state of debris flow, wherein the detection device is the AE.
The level of the signal detected by the sensor is compared with a predetermined threshold value to determine the occurrence of debris flow, and based on the transition of the level of the detection signal of each of the plurality of AE sensors arranged from the upstream to the downstream of the river. A debris flow detection system that calculates the position and speed of the debris flow.

In the debris flow detection system of the present invention, an AE sensor is mounted in a steel pipe, and a plurality of such steel pipes and AE sensors are arranged along the river from upstream to downstream. When debris flow occurs, turbid water increases, and turbid water increases. The contained solids collide with the surface of the steel pipe and generate ultrasonic waves. This ultrasonic wave is detected by the AE sensor in the steel pipe, and the level of this signal is compared with a predetermined threshold value by the detecting device, and depending on the magnitude of the signal level, safety, a precursor of debris flow, occurrence of debris flow, etc. Is determined.

An AE arranged from upstream to downstream
By comparing each detection signal of the sensor, the position where the debris flow occurs can be determined by the signal level of each AE sensor,
The speed is calculated by observing the transition of each signal.

[0010]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows an AE type debris flow detection system according to an embodiment of the present invention,
(A) is an overall configuration diagram, and (b) is a view taken along the line AA.

In FIG. 1, reference numeral 1 denotes a steel pipe,
Is immersed in water in the width direction, and is disposed at a predetermined height from the riverbed 11. Reference numeral 2 denotes a support leg, as shown in FIG. 2B, for fixing the steel pipe 1 to a submerged riverbed 11 and firmly supporting it so as not to be washed away by debris flow. Reference numeral 3 denotes an AE sensor, which is fixed inside the steel pipe 1 as shown in FIG. 1B and detects an ultrasonic signal generated by the steel pipe 1. Reference numeral 20 denotes a detection device which extracts a signal from the AE sensor 3 via a cable 25 and inputs the signal to determine the occurrence of debris flow as described later.

In FIG. 1, three steel pipes 1 and three AE sensors 3 are shown. However, in practice, a debris flow is likely to occur, and an appropriate length of the river 10 for which the debris flow is to be detected is set. During this time, if necessary, a plurality of steel pipes 1 and AE sensors 3 are arranged at a predetermined height in water that is not buried in the riverbed 11 and at specified intervals.

FIG. 2 is a system diagram of the debris flow detection system according to the present embodiment. In the figure, a signal from each AE sensor 3 is input to a detecting device 20 through a cable 25, and a preamplifier 21, a main amplifier 22, a processing determining unit 23
And a display device 24 for displaying the monitoring status of the detection device 20 and the determination result.

In the above configuration, the water quality of the river 10 is good at normal times except during heavy rain, etc., and the solid matter colliding with the surface of the steel pipe 1 due to the flow velocity is very small.
Is hardly detected.

Heavy rain falls on the upstream side of the river 10 to generate debris flow, and the frequency of solids colliding with the surface of the steel pipe 1 increases as the turbid water concentration and the flow velocity increase. Therefore steel pipe 1
Emits ultrasonic waves by this, and the AE sensor 3
Increases the signal level of the ultrasonic wave detected. The state at this time is regarded as a debris flow precursor at the installation position of the AE sensor 3 on the downstream side.

At the bottom of the river together with the turbid water, rocks and the like gradually begin to flow, and the solid matter comes into contact with the steel pipe 1 further, and the detection signal of the AE sensor 3 increases, causing a dangerous state in advance. Can detect.

When a debris flow occurs, the detection signal increases in order from the AE sensor 3 installed on the upstream side to the AE sensor on the downstream side. When the debris flow is received, the detection signal reaches a maximum signal level, and the debris flow continues. During the flow
The state where the E sensor 3 outputs the maximum signal level continues.

The detection signals from the plurality of AE sensors 3 described above are transmitted from the cable 25 to the steel pipe 1 as shown in FIG.
Is guided from the AE sensor 3 into the detection device 20, amplified by the preamplifier 21 and the main amplifier 22, and each detection signal is compared with a predetermined threshold value by the processing determination unit 23. Signs, dangerous situations, etc. are determined,
The result is displayed on the display device 24.

FIG. 3 is a diagram for explaining the state of the judgment in the signal processing section 23 in the detection device 20 described above. The threshold values (S ₁ ) and (S ₂ ) are stored in the signal processing section 23. , (S ₃ )
Is set. Threshold values (S ₁ ), (S ₂ ),
(S ₃ ) respectively correspond to the signal levels V ₁ , V ₂ , V ₃ , and the detection signal level V is substantially 0 <V <until time t _1.
V ₁ , and the signal level V in this state is substantially 0 <V <
S _1, and the determination is "normal state" is determined as "safe".

Between time t _{1 and} t ₂ , the detection signal level V
Is approximately 0 <V <V ₂ , and the detection signal V is
Between ₁ and S _2, or in S ₃ or more states. In this state, “turbid water” is generated, and the amount of turbid water is gradually increasing. At this detected position of the AE sensor, there is a precursor to the occurrence of debris flow. Therefore, the judgment is "light alarm".

Time t_Two~ T_ThreeBetween the detection signal levels V
Is 0 <V <V_ThreeAnd the detection signal V becomes the threshold S_TwoWhen
S_ThreeOr more than that. This S_Two<V
<S _ThreeThe debris flow increases in the condition of
Yes, the determination at this time is determined to be "heavy warning". Furthermore, V
> S_ThreeNow, it is completely debris flow
Is in a state of continuing. Therefore, judgment in this state
Is judged as "heavy warning (continuation of debris flow)".

The determination of the debris flow based on FIG.
For detecting signals from the AE sensors 3 arranged at intervals of
20 and each detection signal V is 0 <V <
S₁, S ₁<V <S_Two, S_Two<V <S_Three, V> S_ThreeNo
The processing determining unit 23 determines whether or not there is a deviation.
Comparing each detection level signal V between each AE sensor
Of debris flow from upstream to downstream
The degree is calculated and can be displayed on the display unit 24.

As described above, according to the present embodiment, the steel pipe 1 is fixed in water at predetermined intervals in the width direction of the river, and the AE sensor 3 is mounted in the steel pipe 1.
The ultrasonic wave generated by the collision between the steel pipe 1 and the solid matter in the water flow is detected by the detection device 20 and guided to the detection device 20. Since the state is determined, the sign of the occurrence of debris flow can be detected early on the downstream side based on the detection signal level based on the turbid water concentration and the flow velocity. Further, the occurrence position, movement position, and speed of the debris flow moving from upstream to downstream can be accurately determined. Furthermore, the installation of the steel pipe 1 is easy, and accurate detection of debris flow is possible with simple equipment.

[0024]

According to the debris flow detection system of the present invention, there are provided a plurality of steel pipes buried in the water of a river and extending in the width direction of the river and fixed to the riverbed at predetermined intervals, and an AE sensor mounted in the steel pipe. And a detecting device which takes in the signal of the sound emitted from the steel pipe detected by each of the AE sensors and determines the state of the debris flow, wherein the detecting device is configured to detect the level of the signal detected by the AE sensor and a predetermined threshold. The values are compared with each other to determine the occurrence of debris flow, and the position and speed of the debris flow are calculated from changes in the levels of detection signals of a plurality of AE sensors arranged from upstream to downstream of the river. . With such a configuration, the debris flow can be easily detected at the signal level detected by the AE sensor, and the precursor of the debris flow can be detected early. Furthermore, the movement of the debris flow, its position and speed can be determined.
In addition, the structure is simple, the installation is easy, and the detection and monitoring of the debris flow are easy.

[Brief description of the drawings]

1A and 1B show an AE debris flow detection device according to an embodiment of the present invention, wherein FIG. 1A is an overall configuration diagram, and FIG.

FIG. 2 is a system diagram of an AE debris flow detection system according to an embodiment of the present invention.

FIG. 3 is a waveform diagram of a detection signal level of the AE debris flow detection system according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional debris flow detection system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Support leg 3 AE sensor 10 River 11 Riverbed 20 Detector 21 Preamplifier 22 Main amplifier 23 Processing judgment part 24 Display part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G01V 9/00 G01V 9/00 Z

Claims (1)

[Claims] 1. A plurality of steel pipes that are buried in the water of a river and extend in the width direction of the river and are fixed to a riverbed at a predetermined interval from each other, an AE sensor mounted in the steel pipe, and each of the AE sensors. A detecting device which receives a signal of a sound emitted from the steel pipe to determine a state of debris flow, wherein the detecting device includes the AE.
The level of the signal detected by the sensor is compared with a predetermined threshold value to determine the occurrence of debris flow, and based on the transition of the level of the detection signal of each of the plurality of AE sensors arranged from the upstream to the downstream of the river. A debris flow detection system that calculates the position and speed of the debris flow.