JP2022135138A - Ground deformation detection device - Google Patents

Abstract

To provide a ground deformation detection device capable of certainly detecting collapse of an inclined plane with a simple device configuration.SOLUTION: A ground deformation detection device 100 includes: a detection unit 130 configured to be able to be inserted into soil 150 to detect moisture of the soil 150; a switching element 120 to be conductive or non-conductive based on a state of the moisture of the soil 150 detected by the detection unit 130; and a light emitting unit 140 for notifying presence or absence of abnormality of the soil 150 based on a voltage of the switching element that varies according to conduction or non-conduction of the switching element 120.SELECTED DRAWING: Figure 1

Description

Applied for application of Article 30, Paragraph 2 of the Patent Act ・Announced at the 62nd Geotechnical Symposium on December 18, 2020 (Sponsored by the Geotechnical Society of Japan: 4-38-2 Sengoku, Bunkyo-ku, Tokyo)

The present disclosure relates to a ground deformation detection device.

In recent years, landslides (surface layer failures), landslides, floods, etc. have occurred on mountainside slopes and naturally steep cliffs due to the effects of torrential rains caused by typhoons, earthquakes, etc., resulting in slope collapse disasters. in an easy situation. Therefore, early detection of slope failure is required.

As a technique for detecting a slope failure, for example, in Patent Document 1, a cable sensor made by coating down a plurality of wires having a specific elongation rate is laid on a slope that is in danger of collapsing. A slope failure prediction system is disclosed that detects a slope failure when a slab is cut. In Patent Document 2, a coaxial cable is sandwiched between two metal fittings facing each other. A slope failure detection device for detecting the occurrence is disclosed.

Japanese Patent No. 3427072 Utility Model Registration No. 2565292

However, the prediction system disclosed in Patent Literature 1 and the slope failure detection device disclosed in Patent Literature 2 require a plurality of parts, which poses a problem of complicating the configuration of the device. In addition, the prediction system disclosed in Patent Document 1 or the like may be cut even if the slope is not collapsed, and there is a problem that the collapse of the slope cannot be detected reliably.

SUMMARY OF THE INVENTION Therefore, in order to solve the above problems, it is an object of the present invention to provide a ground deformation detection device capable of detecting the collapse of a slope or the like with a reliable and simple device configuration.

In order to solve the above problems, the ground deformation detection device invention of the present disclosure is configured to be insertable into soil, and includes a detection unit for detecting the moisture content of the soil, and the moisture content of the soil detected by the detection unit. and a notification unit for notifying the presence or absence of deformation of the soil based on the voltage of the switching element, which varies depending on the conduction or non-conduction of the switching element.

According to the present disclosure, a switching element that is conductive or non-conductive is provided according to the moisture state of the soil detected by the detection unit, and the soil changes based on the voltage of the switching element that varies depending on whether the switching element is conductive or non-conductive. Therefore, it is possible to confirm whether or not a collapse has occurred on a slope or the like with a reliable and simple device configuration.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the example of a schematic structure of the ground deformation detection apparatus which concerns on 1st Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the installation example of the ground deformation detection apparatus which concerns on 1st Embodiment. 5 is a graph showing the relationship between the drain-source voltage and the soil volumetric water content when different resistances are connected between the gate of the switching element and the negative electrode of the power supply according to the first embodiment. FIG. 7 is a diagram showing a schematic configuration example of a ground deformation detection device according to a second embodiment; 8 is a graph showing the relationship between the drain-source voltage and the soil volumetric water content when different resistances are connected between the gate of the switching element and the negative electrode of the power supply according to the second embodiment.

Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[First embodiment]
(Configuration example of ground deformation detection device 100)
FIG. 1 shows an example of a schematic configuration of a ground deformation detection device 100 according to the first embodiment.

As shown in FIG. 1 , the ground deformation detection device 100 includes a power source 110 , a switching element 120 , a soil moisture detection sensor (detection section) 130 and a light emission section (notification section) 140 .

The power source 110 may be, for example, a cell, a battery, a solar charger, an AC power source, or the like. Since the solar charger can generate power, it is suitable when the power source 110 is installed on the slope of a mountain for a long period of time. Moreover, as the power source 110, a soil microbial fuel cell capable of generating power 24 hours a day even at night or in no wind may be adopted without depending on the weather.

The switching element 120 is composed of a P-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The switching element 120 has a gate G1, a drain D1 and a source S1. The drain D1 is connected to the plus side of the light emitting section 140 . Source S1 is connected to the positive side of power supply 110 .

The gate G1 conducts (turns on) or cuts off (cuts off) a current flowing from the source S1 to the drain D1 based on a predetermined voltage applied thereto. The gate G1 is connected to the first electrode 130a of the soil moisture detection sensor 130, and turns on the switching element 120 when a predetermined voltage is applied based on the soil detection state of the soil moisture detection sensor 130. FIG.

A resistor R1 is provided between the gate G1 of the switching element 120 and the negative side of the power supply 110 . In this embodiment, the resistance value of the resistor R1 is set so as to satisfy the following conditions. In general, when the resistance value of the gate G1 is small, the switching time becomes short and linking may occur. When the resistance value of the gate G1 is large, the switching time becomes long, the switching loss increases, and heat is generated. In addition, the moisture content of the soil 150 can be sensitively detected by the soil moisture detection sensor 130 regardless of the state of the moisture content in the soil 150 . In order to satisfy these conditions, it is preferable that the resistance value of the resistor R1 is, for example, 500KΩ to 1MΩ.

The soil moisture detection sensor 130 is a sensor for detecting moisture in the soil 150, and has a pair of first electrode 130a and second electrode 130b. The first electrode 130a is connected to the gate G1 of the switching element 120, and the second electrode 130b is connected to the positive side of the power supply 110. FIG. The soil moisture detection sensor 130 outputs a voltage proportional to the current flowing through the soil 150 based on the electrical resistance of the soil (moisture) 150 between the first electrode 130a and the second electrode 130b. In the present embodiment, soil 150 is used as an example of soil, but the present invention is not limited to this. A sensor 130 can be applied. Further, the soil moisture detection sensor 130 may be a sensor that detects the moisture content of the soil 150 by measuring the dielectric constant of the soil 150, for example.

The first electrode 130a and the second electrode 130b are made of, for example, an elongated rod-shaped member made of carbon material. By making the first electrode 130a and the second electrode 130b rod-shaped, they can be easily inserted into the soil. In addition, by forming the first electrode 130a and the second electrode 130b from a carbon material, the resistivity is low, the heat resistance is high, and the conductivity can be improved. In addition, it has high chemical stability at room temperature, is not corroded by strong acids, alkalis and organic solvents, is hard to break, and can be manufactured at a low cost.

The light emitting unit 140 is installed so as to be exposed from the ground so that it can be visually recognized by the operator. Lights up or goes out. For example, an LED (Light Emitting Diode) can be used for the light emitting unit 140 . The light emitting unit 140 has a plus side connected to the drain D1 of the switching element 120 and a minus side connected to the minus side of the power supply 110 . Note that the notification unit is not limited to the light emitting unit 140, and may be, for example, a voice or warning sound that informs the operator of the moisture content of the soil 150 detected by the soil moisture detection sensor 130. FIG. Information based on the lighting or extinguishing of the light emitting unit 140 is transmitted to the information processing device owned by the worker by wired or wireless communication, and the moisture content of the soil 150 detected by the soil moisture detection sensor 130 is displayed on the screen of the display unit of the information processing device. The detection result may be displayed, or may be notified by voice using a speaker of the information processing device.

(Installation location of the ground deformation detection device 100)
FIG. 2 shows an example of an installation location of the ground deformation detection device 100 according to the first embodiment. The ground deformation detection device 100 is installed, for example, on a slope 300a of a mountain 300, as shown in FIG. Also, the ground deformation detection device 100 may be installed at a plurality of locations along the slope 300a. By installing the ground deformation detection devices 100 at a plurality of locations, it is possible to identify at which height and position the collapse of the slope 300a occurred.

In addition, in FIG. 2, the set of the ground deformation detection device 100 is installed on the slope 300a of the mountain 300, but it is not limited to this. For example, the soil moisture detection sensor 230 can be installed on the slope 300a of the mountain 300, and the light emitting unit 240 and the like can be installed in a building or the like away from the location where the soil moisture detection sensor 230 is installed. Thereby, it is possible to grasp whether or not a collapse has occurred on the slope 300a at a place where safety is ensured. The ground deformation detection device 100 can be installed, for example, on the top surface of a bank formed in a river, on a slope, or on a natural slope or an embankment slope.

(Relationship between drain-source voltage V _DS and volumetric water content of soil 150)
FIG. 3 is a graph showing the relationship between the drain-source voltage V _DS and the volumetric water content of the soil 150 when different resistors R1 are connected between the gate G1 of the switching element 120 and the negative side of the power supply 110. be.

In FIG. 3, the vertical axis indicates the drain-source voltage V _DS and the horizontal axis indicates the volumetric water content of the soil 150 . Also, the voltage of the power source 110 is, for example, 5 V, and the longitudinal length of the first electrode 130a and the second electrode 130b of the soil moisture detection sensor 130 is 50 mm. 10 KΩ, 100 KΩ, 500 KΩ, and 1 MΩ with different resistance values were used as the resistor R1.

As shown in FIG. 3, when the volumetric water content of the soil 150 is 0%, that is, the first electrode 130a and the second electrode 130b of the soil moisture detection sensor 130 are separated from the soil 150 and exposed due to the collapse of the slope 300a. In this state, the switching element 120 was turned off and the drain-source voltage V _DS was 5 V regardless of whether the resistance R1 was 10 KΩ, 100 KΩ, 500 KΩ, or 1 MΩ.

Further, when the resistance R1 is 1 MΩ and the volumetric water content of the soil 150 is about 1.0% or more, the switching element 120 is turned on by connecting the large resistance R1 to the gate G1, and the drain-source The inter-voltage V _DS abruptly dropped to 0V.

Further, when the resistance R1 is 500 KΩ, when the volumetric water content of the soil 150 is about 10% or more, the switching element 120 is turned on by connecting the large resistance R1 to the gate G1, and the drain-source voltage V _DS became 0V.

Further, when the resistance R1 is 100 KΩ, when the volumetric water content of the soil 150 is about 17.5% or more, the switching element 120 is turned on by connecting the large resistance R1 to the gate G1, and the drain-source The inter-voltage V _DS became 0V.

Further, when the resistance R1 is 10 KΩ, even if the volumetric water content of the soil 150 rises to at least around 20%, the drain-source voltage V _DS is maintained at 5 V and hardly changes. rice field.

From these, the larger the resistance R1 connected between the gate G1 and the power supply 110, the more the switching element 120 turns on even when the amount of moisture in the soil 150 is small, and the drain-source voltage V _DS becomes 0V. be able to. Further, in the first embodiment, it is possible to monitor changes in soil moisture by changing the resistance R1 for various types of soil. For example, when the resistance R1 is 1 MΩ and the drain-source voltage V _DS is 0 V, it can be estimated that the volumetric moisture content of the soil 150 is about 1.0% or more. Further, when the resistance R1 is set to 500 KΩ and the drain-source voltage V _DS becomes 0 V, it can be estimated that the volume water content of the soil 150 is about 10% or more.

(Example of operation of switching element 120)
Next, an example of the operation of the ground deformation detection device 100 when detecting collapse of the slope 300a will be described. The voltage of the power supply 110 is set to 5 V, for example, and the resistance value of the resistor R1 connected to the switching element 120 is set to 1 MΩ.

The first electrode 130a and the second electrode 130b that constitute the soil moisture detection sensor 130 are installed, for example, in a state of being embedded in the soil 150 of the slope 300a of the mountain 300 or the like. In this state, if there is no heavy rain, an earthquake, or the like and the slope 300a has not collapsed, the first electrode 130a and the second electrode 130b remain buried in the soil 150. FIG. Soil moisture detection sensor 130 detects moisture in soil 150 between first electrode 130a and second electrode 130b. In the first embodiment, since a large resistor R1 is connected to the gate G1 of the switching element 120, the moisture content of the soil 150 can be sensitively detected even when the moisture content of the soil 150 is very small.

At this time, a voltage higher than the threshold for turning on the switching element 120 is applied to the gate G1 of the switching element 120, and the switching element 120 is turned on. As a result, as shown in FIG. 3, the drain-source voltage V _DS becomes 0 V and the drain current does not flow, so that the light emitting section 140 is extinguished. In the first embodiment, while the first electrode 130a and the second electrode 130b of the soil moisture detection sensor 130 are inserted into the soil 150, the light emitting section 140 is always turned off. By visually confirming that the light emitting unit 140 is turned off, the operator can confirm that the first electrode 130a and the second electrode 130b are buried in the soil 150, and that the slope 300a has collapsed. can confirm that it is not.

On the other hand, for example, when a slope collapses due to the occurrence of heavy rain or the like, the first electrode 130a and the second electrode 130b of the soil moisture detection sensor 130 are separated from the soil 150 by the flow of earth and sand, etc., and reach the surface of the soil 150. becomes exposed. As a result, the space between the first electrode 130a and the second electrode 130b of the soil moisture detection sensor 130 is not the soil 150 but the air, so the output voltage of the soil moisture detection sensor 130 changes according to the electrical resistance of the air. descend.

Therefore, the voltage applied to the gate G1 of the switching element 120 becomes zero, and the switching element 120 is turned off. At this time, as shown in FIG. 3, the drain-source voltage V _DS rises, and the drain current flows to light the light emitting section 140 . By visually confirming that the light emitting unit 140 is lit, the operator confirms that the soil moisture detection sensor 130 is exposed from the soil 150 and that there is a high possibility that the slope 300a has collapsed. can.

According to the first embodiment, a switching element 120 that can be turned on or off according to the moisture state of the soil 150 detected by the soil moisture detection sensor 130 is provided. The presence or absence of deformation of the soil 150 can be notified based on the drain-source voltage V _DS . In other words, whether or not the first electrode 130a and the second electrode 130b are separated from the soil 150 can confirm the collapse of the slope 300a or the like. As a result, it is possible to reliably predict and confirm whether or not the slope 300a or the like will collapse with a simpler device configuration than the conventional one. Moreover, since it is a simple apparatus structure, cost reduction can be achieved.

In addition, since the first electrode 130a and the second electrode 130b are made of a carbon material, even if the first electrode 130a and the second electrode 130b are buried in the soil 150 for a long period of time, corrosion or the like can be prevented. can.

[Second embodiment]
The second embodiment differs from the first embodiment using a P-type MOSFET in that an N-type MOSFET is used as the switching element 220 . In addition, in the ground deformation detection device 200 of the second embodiment, descriptions of the configurations and functions common to the ground deformation detection device 100 of the first embodiment are simplified or omitted.

(Configuration example of ground deformation detection device 200)
FIG. 4 shows an example of a schematic configuration of a ground deformation detection device 200 according to the second embodiment.

As shown in FIG. 4 , the ground deformation detection device 200 includes a power source 210 , a switching element 220 , a soil moisture detection sensor 230 and a light emitter (notifier) 240 .

The switching element 220 is composed of an N-type MOSFET. Switching element 220 has a gate G2, a drain D2 and a source S2. Drain D2 is connected to the negative side of light emitting section 240 . Source S2 is connected to the negative side of power supply 210 .

The gate G2 conducts (conducts) or does not conduct (blocks) the drain current flowing from the drain D2 to the source S2 based on a predetermined voltage applied thereto. In the second embodiment, the gate G2 is connected to the second electrode 230b of the soil moisture detection sensor 230, and is based on a predetermined voltage applied according to the moisture content of the soil 250 detected by the soil moisture detection sensor 230. to turn on the switching element 220 .

A resistor R2 is connected between the gate G2 of the switching element 220 and the negative side of the power supply 210 . As in the first embodiment, the resistance R2 is set to a value that allows the soil moisture detection sensor 230 to sensitively detect the moisture content of the soil 250 regardless of the moisture content of the soil 250 . For example, the resistor R2 preferably has a value of 10KΩ to 100KΩ.

The soil moisture detection sensor 230 is a sensor for detecting moisture in the soil 250, and has a pair of first electrode 230a and second electrode 230b. The first electrode 230 a is connected to the positive side of the power supply 210 and the second electrode 230 b is connected to the gate G2 of the switching element 220 . The first electrode 230a and the second electrode 230b are made of, for example, a carbon material and are elongated rod-like members, which are easily inserted into the soil 250. As shown in FIG.

The light emitting unit 240 is installed at a position exposed from the ground so that it can be visually recognized by the operator, and is lit when the switching element 220 becomes conductive or non-conductive according to the result of detection of the moisture content of the soil 250 by the soil moisture detection sensor 230. Or turn off the light. For example, an LED can be used for the light emitting unit 240 . The light emitting unit 240 has a positive side connected to the positive side of the power source 210 and a negative side connected to the source S2 of the switching element 220 .

(Relationship between drain-source voltage V _DS and volumetric water content of soil 250)
FIG. 5 is a graph showing the relationship between the drain-source voltage V _DS and the volumetric water content of the soil 250 when different resistors R2 are connected between the gate G2 of the switching element 220 and the negative side of the power supply 210. be.

In FIG. 5, the vertical axis indicates the drain-source voltage V _DS and the horizontal axis indicates the volumetric water content of the soil 250 . Also, the voltage of the power source 210 is, for example, 5 V, and the longitudinal length of the first electrode 230a and the second electrode 230b is 50 mm. 10 KΩ and 100 KΩ having different resistance values were used as the resistor R2.

As shown in FIG. 5, when the volumetric water content of the soil 250 is 0%, that is, the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 are pulled out of the soil 250 and exposed due to the collapse of the slope 300a. In this state, the switching element 220 was turned off and the drain-source voltage V _DS was 0 V regardless of whether the resistance R2 was 10 KΩ or 100 KΩ.

Further, when the volumetric water content of the soil 250 is about 1% or more, that is, when the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 are inserted into the soil 250 containing moisture, the switching element 220 turned on, and the drain-source voltage V _DS became about 4.5V. The response of the drain-source voltage V _DS was almost the same regardless of whether the resistance R2 was 10 KΩ or 100 KΩ.

(Example of operation of switching element 220)
Next, an example of the operation of the ground deformation detection device 200 when detecting collapse of a slope will be described. The voltage of the power supply 210 is set to 5 V, for example, and the resistance value of the resistor R2 connected to the switching element 120 is set to 100 KΩ.

The first electrode 230a and the second electrode 230b that constitute the soil moisture detection sensor 230 are installed by being inserted into the soil 250 of the slope 300a such as the mountain 300, as shown in FIG. In this state, if there is no heavy rain or earthquake and the slope 300a has not collapsed, the first electrode 230a and the second electrode 230b remain buried in the soil 250. FIG. Soil moisture detection sensor 230 detects moisture in soil 250 between first electrode 230a and second electrode 230b. In the second embodiment as well, since the large resistor R2 is connected to the gate G2 of the switching element 220, even if the moisture content of the soil 250 is very small, the moisture content of the soil 250 can be sensitively detected.

At this time, a voltage higher than the threshold for turning on the switching element 220 is applied to the gate G2 of the switching element 220, and the switching element 220 is turned on. As a result, as shown in FIG. 5, the drain-source voltage V _DS rises, and the drain current flows to light the light emitting section 240 . In the second embodiment, while the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 are inserted into the soil 250, the light emitting section 240 is always lit. By visually confirming that the light emitting part 240 is lit, the operator can confirm that the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 are buried in the soil 250, and the slope 300a It can be confirmed that the collapse of

On the other hand, for example, when a slope collapses due to the occurrence of heavy rain or the like, the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 are separated from the soil 250 by the flow of earth and sand, etc., and reach the surface of the soil 250. becomes exposed. As a result, the space between the first electrode 230a and the second electrode 230b of the soil moisture detection sensor 230 is not soil 250, but air, so that the output voltage of the soil moisture detection sensor 230 varies depending on the electrical resistance of the air. decreases.

Therefore, the voltage applied to the gate G2 of the switching element 220 becomes zero, and the switching element 120 is turned off. At this time, as shown in FIG. 5, the drain-source voltage V _DS is 0 V, and no drain current flows, so the light emitting section 240 is turned off. By visually confirming that the light emitting unit 240 is turned off, the operator confirms that the soil moisture detection sensor 230 is exposed from the soil 250 and that there is a high possibility that the slope 300a has collapsed. can.

According to the second embodiment, as in the first embodiment, a switching element 220 that can be turned on or off according to the moisture state of the soil 250 detected by the soil moisture detection sensor 230 is provided. Since the presence or absence of deformation of the soil 250 can be notified based on the drain-source voltage V _DS that fluctuates depending on whether the switching element 220 is turned on or off, the collapse of the slope 300a or the like can be reliably prevented with a simpler device configuration than before. Presence or absence can be predicted and confirmed. Moreover, since it is a simple apparatus structure, cost reduction can be achieved.

The embodiments of the present disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes designs and the like within the scope of the present disclosure. Also, the effects described in this specification are only examples and are not limited, and other effects may be provided.

100, 200 ground deformation detection device 110, 210 power source 120, 220 switching element 130, 230 soil moisture detection sensor (detection unit)
130a, 230a 1st electrodes 130b, 230b 2nd electrodes 140, 240 light emitting part (informing part)
150, 250 Earth D1, D2 Drain G1, G2 Gate R1, R2 Resistor S1, S2 Source

Claims (8)

a detection unit that is configured to be insertable into soil and detects moisture in the soil;
a switching element that is conductive or non-conductive based on the moisture state of the soil detected by the detection unit;
a notification unit that notifies the presence or absence of deformation of the soil based on the voltage of the switching element that varies depending on whether the switching element is conductive or non-conductive;
Ground deformation detection device. The switching element is a P-type MOSFET having a gate, a drain and a source,
The detection unit has a first electrode and a second electrode,
the gate is connected to the first electrode;
said source is connected to the positive side of a power supply,
the second electrode is connected to the positive side of the power supply;
The reporting unit is connected to the drain and to the negative side of the power supply,
A resistor is provided between the gate and the negative side of the power supply,
the value of the resistance is between 500 KΩ and 1 MΩ;
The ground deformation detection device according to claim 1. when the soil contains water, the MOSFET conducts so that the voltage between the drain and the source of the MOSFET maintains a value of zero;
The notification unit notifies the presence or absence of deformation of the soil based on the drain-source voltage.
The ground deformation detection device according to claim 1 or 2. The notification unit is a light emitting unit that turns on and off,
The light is turned off when the soil contains moisture, and the light is turned on when the soil does not contain moisture.
The ground deformation detection device according to claim 1. The switching element is an N-type MOSFET having a gate, a drain and a source,
The detection unit has a first electrode and a second electrode,
the gate is connected to the second electrode;
said source is connected to the negative side of a power supply,
the first electrode is connected to the positive side of the power supply;
The notification unit is connected to the drain and to the positive side of the power supply,
A resistor is provided between the gate and the negative side of the power supply,
the resistance value is between 10 KΩ and 100 KΩ;
The ground deformation detection device according to claim 1. when the soil contains moisture, the MOSFET is turned on so that the voltage between the drain and the source of the MOSFET is maintained at a predetermined voltage value;
The notification unit notifies the presence or absence of deformation of the soil based on the drain-source voltage.
The ground deformation detection device according to claim 5. The notification unit is a light emitting unit that turns on and off,
The light is turned on when the soil contains moisture, and the light is turned off when the soil does not contain moisture.
The ground deformation detection device according to claim 5. The first electrode and the second electrode of the detection unit are made of a carbon material, and detect whether the soil contains moisture based on the electrical resistance of moisture in the soil.
The ground deformation detection device according to any one of claims 1 to 7.

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