JP3233398B2 - Water leak detection device and water leak detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of water leakage using an electric current method, and more particularly, to the underground or surrounding environment of water contaminated by waste deposited in a recess such as a general waste disposal site. TECHNICAL FIELD The present invention relates to a water leak detection device and a water leak detection method for detecting intrusion into water.

[0002]

2. Description of the Related Art In a waste disposal site where a large recess is provided in the ground and general waste and industrial waste are dumped in the recess, rainwater permeated into the waste is contaminated by the waste. In order to prevent the generated sewage from penetrating into the ground and remarkably contaminating the groundwater and the surrounding environment, various water-blocking structures are installed on the bottom and slopes of the recess.

[0003] Examples of the water-blocking structure include a structure in which a water-blocking sheet is provided on the bottom and the slope, a structure in which a clay layer is provided on the bottom and the slope, and a structure in which the bottom and the slope are made of concrete having water-blocking properties. It has been known. In particular, at managed industrial waste disposal sites and general waste disposal sites, waterproofing is achieved by using double impermeable sheets, or by using both impermeable sheets and cohesive soil layers or impermeable sheets and asphalt concrete.
More certainty is being done.

The above-mentioned waste disposal sites are provided with a water-blocking structure, but in order to prevent sewage from penetrating into the ground and polluting the environment, it is necessary to make sure that water is not constantly leaking in case of emergency. Investigation and monitoring are being conducted. As a water leakage detection method in such a waste disposal site, for example, a water quality analysis method, a vacuum suction method, an electric detection method, and the like are conventionally known.

[0005] Among the above-mentioned methods, the water quality inspection method involves, for example, collecting spring water or groundwater from a waste disposal site through a groundwater collecting and draining pipe provided at a lower portion of a water shielding structure, flowing the collected water into a groundwater pit, This is a method of detecting water leakage due to damage to the impermeable sheet by sampling and investigating the quality of groundwater. This method has the advantages that it can be applied without greatly changing the structure of a conventional waste disposal site or the like, and that the components of water leakage can be specified by sampling investigation.

In the vacuum suction method described above, the space between the double water-impervious sheets is divided into a bag shape, and the change in vacuum pressure is measured by vacuum-suctioning the inside of each of the bag-shaped blocks. This is a method for detecting the presence or absence of breakage of the impermeable sheet. This method has an advantage that a damaged location can be specified in block units.

[0007] The above-mentioned electrical detection method includes a potential method for detecting the presence and location of breakage of the water-impervious sheet based on the potential distribution distortion caused by the breakage of the water-impervious sheet, and an electric current generated by the breakage of the waterproof sheet. Current method for detecting the presence and position of sheet breakage from the ease of flow, potential, measuring the potential and specific resistance distribution, and detecting the presence or absence and position of sheet breakage from the vertical current calculated by predetermined calculation・ There is a specific resistance method.

FIG. 16 shows a water leak detection method using the electric potential method among such conventionally used electric detection methods. The conventional potential method shown in FIG. 16 utilizes the electrical insulation properties of the water-impervious sheet 100, and includes electrodes 101,
The potential measurement electrode 103 and its reference electrode 104 are arranged on the upper surface of the water-impervious sheet 100.
If the water impermeable sheet 100 is damaged, the electrode 101
Current flows through the damaged portion 105 between the
An electric circuit is formed. At this time, the potential between the potential measurement electrode 103 and the reference electrode 104 is measured to determine the potential distribution on the surface of the impermeable sheet, and the position of the damaged portion 105 is specified from the shape of the potential distribution. Have been.
The potential measurement electrode 103 and the reference electrode 104 can be installed on the lower surface of the water-impervious sheet 100, and the potential measurement electrode 103 and the reference electrode 10
The position of the damaged portion 105 is specified by measuring the potential of the damaged portion 105.

However, the electric detection method using the conventional potential method as described above can detect water leakage and specify the location of the water leakage. However, the accuracy of specifying the position of the damaged portion of the impermeable sheet is low. There is a problem in that it is influenced by electric noise at the time of measuring the potential and a change in the specific resistance value of a peripheral material provided with the potential measuring electrode. For example, when the potential measurement electrode is installed on the upper surface of the impermeable sheet, that is, inside the landfill, the shape of the potential distribution changes due to the progress of the landfill and changes in the water level inside the landfill layer, The accuracy of specifying the location of the damaged portion of the impermeable sheet will be affected. In addition, when the potential measurement electrode is installed on the lower surface of the impermeable sheet, that is, outside the landfill, the environment such as the groundwater level changes by constructing a waste disposal site in a recess. As a result, the shape of the potential distribution may change.

As an electrical detection method, a method using a current is also known. For example, Japanese Patent Application Laid-Open No. 9-29022
No. 8 and Japanese Patent Application Laid-Open No. Hei 10-300622 disclose a water leakage detection device or a water leakage detection system using a current method. Japanese Patent Application Laid-Open No. 9-290228 discloses a water leakage detection device using a water-impervious and electrically insulating water-impervious sheet in which a number of pairs of conductive wires for voltage application and conductive wires for current detection are arranged. Is disclosed. JP 9
The water leakage detection device disclosed in Japanese Patent Application Laid-Open No. 290228/1990 is capable of detecting a leakage current caused by water leakage inside the water-impervious sheet by using the above-described water-impervious sheet having a current detection lead.

However, in the water leakage detecting device disclosed in Japanese Patent Application Laid-Open No. 9-290228, a plurality of conductive wires having a complicated shape must be arranged inside the water-impermeable sheet, and the strength of the water-impermeable sheet is reduced. It is still insufficient with respect to the water shielding and the detectability of the water leakage position, such as the fact that the water leakage is likely to occur, or that the water generated by the water leakage fills the inside of the water shielding sheet, making it difficult to identify the water leakage position. It's difficult.

Japanese Patent Application Laid-Open No. Hei 10-300622 discloses that a resistance wire having a known resistance per unit length is arranged on the ground side of a water-impervious sheet laid in a concave part of the ground, and the water-impervious sheet is sandwiched between the resistance lines. When a constant current power supply is placed on the side facing away from the water impervious sheet, a constant current flows from the constant current power supply through the damaged part of the water impervious sheet when water leakage occurs, A water leakage detection system that detects water leakage by using a voltage drop according to the length of a resistance wire and detects a water leakage position is disclosed.

According to this water leakage detection system, although it is possible to detect water leakage and to detect the position of water leakage, since a resistance wire or the like is arranged adjacent to the water impermeable sheet, it is necessary to maintain the water impermeability of the water impermeable sheet. In addition, there is a problem that a construction is required in which a resistance wire or the like is sandwiched between a plurality of felt layers adjacent to the water impermeable sheet, and the cost required for the water impermeable work is high.
In addition, the detection of a leak location uses a voltage drop caused by a constant current flowing for a fixed distance from the leak location to the terminal connected to the electrometer. If it is localized to
Although it is possible to accurately detect a leaking point, there is a problem that it becomes difficult to identify the leaking point as the sewage infiltrates the felt layer.

Further, in the potential / resistivity method, a change in the specific resistance around the potential measuring electrode can be detected, so that a change in the shape of the potential distribution does not affect the location of the damaged portion of the water-impermeable sheet. However, there is a problem that measurement and analysis of the specific resistance require time and technology.

[0015]

In view of the above problems,
The present invention quickly detects the infiltration of sewage contaminated by dumped waste into the ground by using the electric current method at a waste disposal site, detects water leakage, and detects the resistivity distribution of the ground and waste. Water leakage detection device and water leakage detection that are less likely to be affected, and are less affected by noise than the potential method, can accurately determine the water leakage position, and do not reduce the water shielding of the water shielding part The aim is to provide a method.

[0016]

The above objects of the present invention can be attained by providing a water leak detecting device and a water leak detecting method according to the present invention.

That is, according to the present invention, a water-impervious structure including a concave part in the ground and a water-impervious part laid on the ground along the concave part and subjected to a water-impervious treatment is formed from the concave part. A water leakage detection device for detecting water leakage to the ground, a plurality of point electrodes disposed on the ground adjacent to the water shielding portion,
A concave electrode disposed in the concave, a power supply for flowing a current between the point electrode and the concave electrode, and a current for measuring a leakage current generated by water leakage from the concave to the ground. Measuring means, electrode switching means, and control means for forming a different leakage current path between the concave electrode and each of the point electrodes, wherein the water impermeability of the leakage current flowing through the leakage current path is provided. A leak detection device is provided, wherein a leak location is detected based on a current distribution across a portion.

According to the present invention, the electrode switching means switches and connects the recessed electrode and one of the plurality of point electrodes to form a plurality of the leakage current paths. A sensing device is provided.

According to the present invention, the water leakage detection device further includes a reference electrode, and the detection of a water leakage point is performed by the following expression (2) of a leakage current and a current flowing between the concave electrode and the reference electrode. 1)

(Equation 3) Is provided by using the ratio (K) given by the following formula (1), wherein I is a leakage current, and Ir is a difference between the concave electrode and the reference electrode. Indicates the current flowing between them.)

According to the present invention, there is provided a water leakage detecting device , wherein the electrode switching means forms a plurality of the leakage current paths in parallel between the concave electrode and the point electrode.

According to the present invention, there is provided a water-impervious structure having a concave portion in the ground and a water-impervious portion laid on the ground along the concave portion and subjected to a water-impervious treatment. A water leakage detection method for detecting water leakage to the ground, comprising: a plurality of point electrodes disposed on the ground adjacent to the water shielding portion; a concave electrode disposed on the concave; A power supply for flowing a current between the electrode and the concave electrode, a current measuring unit for measuring a leakage current generated by water leakage from the concave to the ground, an electrode switching unit, and the electrode switching unit. Using a water leakage detection device with a control means for controlling, at the time of water leakage from the water blocking portion to the ground, to form a plurality of leakage current paths between the concave electrode and each of the point electrodes, The leakage current flowing in the leakage current path is measured in the area along the impermeable part. And water leakage detection method characterized by detecting the leak portion by the current distribution over the above water-barrier portion of the leakage current flowing through the leakage current path is provided.

According to the present invention, the water leakage detection device is characterized in that the electrode switching means is driven so that the plurality of water leakage paths are formed between the concave electrode and one of the plurality of point electrodes. A method is provided.

According to the present invention, the water leakage detection device further includes a reference electrode, and the detection of the water leakage location is performed by the following equation (4) of the leakage current and the current flowing between the concave electrode and the reference electrode. 1)

(Equation 4) 6. The method according to claim 5, wherein the method is performed using a ratio (K) given by the following formula (1): wherein I is a leakage current, and Ir is the recess. The current flowing between the electrode and the reference electrode is shown.)

According to the present invention, there is provided a method for detecting water leakage, wherein the electrode switching means is driven so that a plurality of the leakage current paths are formed in parallel between the recessed electrode and the point electrode. Provided.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a water leak detecting apparatus and a water leak detecting method according to the present invention.

FIG. 1 is a diagram showing a schematic cross section of a waste disposal site to which the water leakage detection device of the present invention is applied. The waste disposal site to which the present invention is applied includes a concave portion of the ground 1 and a water shielding portion 2 disposed on the ground 1 along the concave portion. The concave portion of the ground 1 may be formed artificially by digging from the surface of the ground toward the foundation ground, and when a swamp or a valley such as a mountain area is used, its topography can be used. The waste 3 is dumped in such a recess, and the sewage generated by rainwater or the like is prevented from leaking out by the impermeable portion 2.

In FIG. 1, the water-impervious portion 2 is provided below the water-impervious sheet 5, a sand layer or soil 4 adjacent to the waste 3, a water-impervious sheet 5 adjacent to the sand layer or soil 4. And a low water-permeable structure 6. Impermeable sheet 5
Examples of the sheet include a sheet made of synthetic rubber or plastic, specifically, a sheet made of high-density polyethylene (HDPE), and the like. Anything that can be used can be used.

The above-described low water-permeable structure 6 is a soil water-blocking layer made of a soil material or a water-blocking layer made of asphalt. Specifically, a material having low water permeability such as viscous soil, asphalt and concrete is used. And these can be used in combination as appropriate. Moreover, although the above-mentioned waterproof sheet 5 has been described as having a single structure, it is also possible to use a double waterproof sheet.

FIG. 2 is a view showing a water leakage detecting device according to a first embodiment of the present invention. The water leak detecting device according to the first embodiment of the present invention It has a plurality of point electrodes 7 arranged and a recess electrode 8 arranged in the recess. The point electrode 7 used in the present invention is formed to be sufficiently small with respect to the area of the water shielding portion 2 and the interval at which the point electrodes 7 are arranged, so that the point electrode 7 can detect a water leakage position with sufficient accuracy. Refers to an electrode formed in dimensions and shapes. Further, the point electrode 7 can be formed from various materials such as iron, copper, lead, and stainless steel, and is not disposed in the concave portion. Therefore, the point electrode 7 does not need to be formed from a particularly corrosion-resistant material. . In addition, the point electrode 7 may be provided with a protrusion facing the ground side in order to improve the holding property to the ground 1 and improve the workability of the water shielding work. The recess electrode 8 in the present invention refers to an electrode arranged in the recess, and may be arranged at any position as long as it is adjacent to the waste 3 and can flow current due to water leakage. .

In the water leakage detecting device according to the first embodiment of the present invention shown in FIG. 2, a power source 9 is connected between the point electrode 7 and the concave electrode 8, and both ends of the power source 9 are connected. It is shown that an electrometer 10 for measuring the electric potential is provided. The power supply 9 is used to detect the occurrence of a leak and the position of the leak by causing a leak current to flow along a leak current path caused by the leak when the leak occurs from the water-blocking portion 2. At this time, the leakage current flowing along the leakage current path caused by the water leakage is detected by current detecting means such as the ammeter 11. The electrometer 10 connected to both ends of the power supply 9 directly measures the potentials at both ends of the input / output terminals of the power supply 9, but the conductive wire 1 connected to the power supply 9
2 has a low resistance, so that a potential corresponding to the potential difference between the point electrode 7 and the concave electrode 8 is applied. In each of the embodiments of the present invention, the electrometer 10 is disposed adjacent to both ends of the power supply 9, but any portion may be connected as long as the potential difference between the recessed electrode 8 and the point electrode 7 can be measured. It may be. In the water leakage detecting device according to the first embodiment of the present invention shown in FIG. 2, no leakage current is shown in the water-impervious sheet 5 because there is no breakage portion.

FIG. 2 shows an electrode switching means 13 used in the water leakage detecting device according to the first embodiment of the present invention. In the first embodiment of the water leakage detection device of the present invention, the electrode switching means 13 is connected between the power supply 9 and the point electrode 7 to form one of the recessed electrode 8 and the plurality of provided point electrodes 7. And a leakage current path is formed between them. Further, the electrode switching means 13 is connected to one point electrode 7 connected to the recessed electrode 8 by a control device (not shown).
Is selected to perform the switching connection. By switching the point electrode 7 connected as described above by the electrode switching means 13, a plurality of leakage current paths having different distances in the ground 1 between the recessed electrode 8 and the point electrode 7, that is, having different resistance values. Is formed, it is possible to form a plurality of leakage current paths having different current intensities extending from the water leakage point to the selected point electrode 7.

In the water leakage detecting device according to the first embodiment of the present invention, a plurality of leakage current paths are formed by sequentially switching the point electrodes 7 over the water blocking portion by the electrode switching means 13 as described above. In this way, the location of the leak is identified. However, in order to more accurately measure the leak location using a power supply such as a constant current power supply, FIG.
In the water leakage detection device according to the first embodiment of the present invention, a reference electrode 21 is provided in the ground 1 or on the surface of the ground sufficiently away from the waste disposal site, and an ammeter for monitoring the reference current Ir. 22 and the power supply 9 via the electrode switching means 13.
And the recessed electrode 8. This reference electrode 21 is shown in FIG. 2 as being arranged in the ground 1, and can be optionally turned on / off by the electrode switching means 13.

FIG. 3 is a view showing a water leakage detecting device according to a second embodiment of the present invention. In the water leakage detecting device according to the second embodiment of the present invention, it is shown that an ammeter 11 is connected to each point electrode 7. The electrode switching means 13
By connecting the plurality of point electrodes 7 or all the point electrodes 7 to the power source 9 at the same time by the control means 14, a plurality of leakage current paths due to water leakage are formed in parallel between the point electrode 7 and the concave electrode 8. Is controlled to be formed. In the water leakage detection device according to the second embodiment of the present invention, the ammeter 11 must be connected to all the point electrodes 7, but the current intensity measurement of all the formed plural leakage current paths is performed at once. In order to make it possible, it is possible to reduce the time required for water leak detection. Also, in FIG.
An ammeter 11 is further connected between the power supply 9 and the recess electrode 8 to monitor the total current supplied by the power supply 9. The ammeter 11 may be used to prevent the power supply 9 from being overloaded.

FIG. 4 shows a point electrode 7, a concave electrode 8, a power supply 9, an electrometer 10, an ammeter 11, and an electrode switching means of the water leakage detecting device of the present invention arranged over the water shielding section 2. 13
FIG. 2 is a plan view showing an arrangement of control means 14. FIG. 4 shows that the point electrodes 7 are arranged at a constant interval a in the water shielding section 2 of the waste disposal plant. The interval a at which the point electrodes 7 are arranged is not particularly limited, but is preferably arranged at such an interval as to be able to detect the water leakage position with the accuracy required in the present invention.
The distance can be between 5 m and 10 m.

As shown in FIG. 4, the water leakage detecting device of the present invention comprises an ammeter 11, a power source 9,
The electrode switching unit 13 is connected. The ammeter 11 measures the intensity of the leakage current and sends the measured value to the control means 14. The control means 14 controls the recording means so that the two
The dimensional position and the intensity of the leakage current are stored. Ammeter 11
Alternatively, the control means 14 may be provided with a function such as A / D converter means for digitizing an analog signal such as current intensity, and the A / D converter means is provided between the ammeter 11 and the control means 14. It can be provided separately between them.

As the control means 14 used in the present invention, various computer means can be used. This control means 14 measures the intensity of the measured leakage current and the two-dimensional position of the point electrode 7 where water is leaking. Recording means such as a hard disk, a floppy disk, and a magnetic tape for recording the information.

As the above-mentioned control means 14, specifically, for example, a personal computer can be used. This personal computer is, for example, a CPU (Central Processing Unillustrated) not shown.
it) and RAM (Random Access Me)
memory) and ROM (Read Only Memo)
ry), an external storage device, input / output control means, etc., for controlling the power supply 9, controlling the electrode selection operation of the electrode switching means 13, controlling the operation of the electrometer 10 and reading the measured values,
The reading of the measurement value of the ammeter 11 is performed. The control means 14 has a program for detecting water leakage and determining the position of water leakage from the measured current distribution, and is adapted to determine the occurrence of water leakage and the position of water leakage. In addition, a function may be provided that displays the result of water leakage determination and automatically notifies the relevant organization when water leakage is detected.

The power supply 9 shown in FIG.
An AC power supply may be used, and a constant voltage power supply, a constant current power supply, or a combination of a constant voltage power supply and a constant current power supply may be used as appropriate. The power supply 9 is turned on / off by the control means 14 to perform or end the water leak detection operation as necessary. Electrometer 10
It is connected to the input / output terminal of the power supply 9 and measures the potential applied between the point electrode 7 and the concave electrode 8 during the water leak detection operation. The output of the electrometer 10 may be input to the control means 14 and fed back to the power supply 9 through the control means 14 so as to prevent the power supply 9 from being overloaded.

The power supply 9 is further connected to an electrode switching means 13, which selectively switches and connects one point electrode 7 in the water leakage detecting device according to the first embodiment of the present invention. Then, the control means 14 forms one leakage current path between one point electrode 7 and one concave electrode 8.
Is controlled by Further, the above-described electrode switching means 1
3, in the water leakage detecting device according to the second embodiment of the present invention, the power supply 9 is connected to all the point electrodes 7, and a plurality of parallel leakage current paths are formed between the concave electrode 8 and all the point electrodes 7. It is controlled by the control means 14 to form. As the electrode switching means 13 described above, knife switching means,
Any conventionally known mechanical, electrical or electronic means such as electric relay means, thyristors and the like can be used. Although the electrode switching means 13 is described as being provided separately from the control means 14 in FIGS. 2, 3, and 4, it may be configured as a module integrated with the control means 14. It is possible.

Next, a method for detecting water leakage according to the first embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the water leakage detection device according to the first embodiment of the present invention, taken along a cutting line AA shown in FIG. In FIG. 5, it is assumed that water is leaking from the water leaking point 15 of the water impermeable sheet 5. In the water leakage detection method of the present invention,
If there is no broken portion, no current path is formed between the recessed electrode 8 and the point electrode 7, and no current flows, or even a very weak current flows. However, once as shown in FIG. 5, between the recess electrode 8 and the point electrode 7a, the leakage current path 16 through the leak portion 15 is formed, the leakage current I ₁ flows. This leakage current I
₁ is detected by the ammeter 11 and after the A / D conversion is performed, the current intensity is recorded by the control means 14.
It is to be noted that the ammeter 11 shown in FIG.
Although it is arranged at a position different from the position shown in, as long as the arrangement is such that leakage current can be appropriately detected and a signal can be sent to the control means 14, it is arranged at any position. May be. Point electrode 7a shown in FIG.
Is closest to the water leaking point 15, so that a leak current having the highest current value flows between the concave electrode 8 and the point electrode 7a.

Next, the control means 14 in the water leakage detecting method according to the first embodiment of the present invention switches the electrode switching means 13 to the point electrode 7b shown in FIG. 8 and the point electrode 7b are sequentially connected to form a leakage current path different from the leakage current path 16 formed between the concave electrode 8 and the point electrode 7a. In this way, a leakage current path 17 indicated by a broken line is formed between the concave electrode 8 and the point electrode 7b. The leakage current path 17 thus formed is farther from the water leakage point 15 than the leakage current path 16, and the low water permeable structure 6 is provided immediately below the water leakage point 15, so that The diffusion of sewage in the direction is small enough that the resistance is high. As a result, the leakage current I ₂ flowing through the leakage current path 17 will be smaller in comparison with the leakage current I ₁ flowing through the closest portion to the leak location 15.

The above measurement is repeated for all the point electrodes 7, and the current distribution is obtained by plotting the leakage current over the entire water shielding section 2. This current distribution is
Giving a sharp structure around the leakage current I ₁ as described above, it is possible to perform the determination of the water leakage position 15 with higher accuracy.

Further, in the water leakage detecting method according to the first embodiment of the present invention, the leakage current I flowing through the point electrode 7 and
It is also possible to more accurately determine the location of the water leak using the above-mentioned ratio K of the reference current Ir flowing between the reference electrode 21 and the recessed electrode 8 as expressed by the following equation (1).

[0044]

(Equation 5)

That is, the current Ir flowing between the reference electrode 21 and the power supply 9 is constantly measured by the ammeter 22. Next, the leakage current is measured by switching the point electrodes 7 one by one.
Among the point electrodes 7, the point electrode 7 a closest to the water leakage point is:
As shown in FIG. 5, a large leakage current I is compared with Ir.
= I ₁ flows, the ratio K given by the above equation (1)
Becomes larger. On the other hand, the electrode 7b point located far from the leak point 15, the leakage current I = I ₂ approaches the Ir, becomes about one size substantially. Therefore, it is also possible to obtain the value of K for all the point electrodes 7 to obtain a distribution of the value of K, and to set the position where the value of K becomes the maximum value as the water leakage position. In FIG. 5, the reference electrode 21 is shown in the vicinity of the point electrode 7b for convenience. However, in reality, the reference electrode 21 is sufficiently separated so as not to be affected by the water leakage from the water shielding section 2, so that the water leakage is prevented. When this occurs, a maximum value is always formed at the water leakage position. By doing so, it is also possible to correct the influence of fluctuations in the groundwater level of the ground 1, etc.
Further, the leakage current can be estimated by plotting the leakage current as a distribution of K and interpolating using a spline function or the like.

FIG. 6 is a diagram showing a second water leakage detection method according to the present invention when water leakage is detected using the water leakage detection device according to the second embodiment of the present invention. In the water leakage detection method according to the second embodiment of the present invention, each point electrode 7 is provided with an ammeter 11
Is connected, and the electrode switching means 13 is connected between the recessed electrode 8 and all the point electrodes 7 in parallel with the leakage current paths 18, 19, 2.
0 is controlled. In FIG. 6, the leakage currents I ₃ , I ₄ ,
It has been shown to I ₅ is flowing. As mentioned above,
In the water leakage detection method using the water leakage detection device according to the second embodiment of the present invention, a leakage current flows between all of the point electrodes 7, but in FIG. 3 shows only the leakage current. In the water leak detection method according to the second embodiment of the present invention shown in FIG.
As compared with the water leakage detection method shown in FIG. 5, although the number of required ammeters 11 is increased, it is possible to perform the leakage current measurement for all the point electrodes 7 in one measurement, so that the measurement for performing the water leakage detection is performed. Time can be shortened, and more rapid water leak detection can be performed.

In the following, the results of a numerical experiment of the above-described water leakage detection device and water leakage detection method will be described. In the numerical experiments, (1) detectability of water leakage position, (2) point electrode 7
(3) Simultaneous detection of a plurality of leaked points when water leakage occurred when measurement was impossible due to disconnection or the like (hereinafter referred to as electrode loss).

The leak detection performance of the above-described leak detecting device and leak detecting method was analyzed using a pseudo three-dimensional finite element method in which a grid was formed using the two-dimensional coordinates of the point electrode 7 and the leak current I. In the numerical calculation, the water-impervious sheet 5 was made to be a complete insulator, and it was assumed that water leaked from the water leak location 15. The point electrodes 7 were arranged at intervals of 5 m 50 cm below the impermeable sheet 5. Further, when examining the detectability of the water leakage position, the water leakage point 15 is 0 m around one point electrode 7 (the reference point electrode 7 position).
From 1 to the next point electrode 7 which is 5 m apart every 1 m.

Further, as for the ground 1, in order to examine the influence of the resistivity distribution, it is assumed that the ground is a homogeneous ground having a uniform resistivity distribution and a heterogeneous ground having a non-uniform resistivity distribution. Numerical calculation. The homogeneous ground has a specific resistance of the ground 1 including the low permeable layer 6 which is uniform in any direction.
Numerical calculations were performed on the assumption that the specific resistance was randomly distributed from 25 Ωm to 100 Ωm with the center value of 50 Ωm as the center value. For comparison, when a constant current is supplied from the constant current power supply through the water leakage point 15 from the power supply 9, the above described homogeneity of the leak detection method by the potential method using the potential difference between the point electrodes 7 is described above. Numerical calculations were performed for the ground and heterogeneous ground. The above-described model calculations were performed using a model that simultaneously measures leakage current when leakage current paths are formed in parallel.

(1) Examination of Water Leak Detection Position FIGS. 7 and 8 show the water leak detection device and the water leak detection method of the present invention in which the distance from the center point electrode 7 (0 m position) of the water leak position 15 to the water leak position is changed. FIG. 5 is a diagram showing, for example, a distribution along a section line AA in FIG. 4 showing model calculation results performed on a homogeneous ground and a non-homogeneous ground in each case. FIG. 7 and FIG. 8 show that two peaks are obtained. This is because the water leak position 15 is moved from the 0 m position to the next point electrode 7 in order, and
Corresponding to water leakage at the 0 m position where the highest peak is obtained at the point electrode 7 at the m position and water leakage at the 5 m position where the highest peak is obtained at the electrode 7 5 m away from the point electrode 7 at the 0 m position. It is.

As shown in FIGS. 7 and 8, in the water leakage detection device and the water leakage detection method according to the present invention, it can be seen that the maximum current is obtained near the water leakage position on the homogeneous ground or the heterogeneous ground. Have been. 7 and FIG. 8,
Although there is a certain difference in the peak height, it can be seen that the peak position does not change in the current distribution due to the resistivity distribution.

FIGS. 9 and 10 show, similarly to FIGS. 7 and 8, numerical calculation results obtained when the potential method is used for the homogeneous ground and the heterogeneous ground, respectively, for example, along the cutting line A-FIG. FIG. 6 is a diagram shown as a distribution along A. FIG.
In the numerical calculation for the inhomogeneous ground shown in FIG. 7, although the relative relationship between the peak potentials fluctuates, it can be seen that two peak potentials similar to those in FIGS. 7 and 8 are obtained by the potential method. However, paying attention to the tail of the potential distribution, it can be seen that the tail of the distribution is larger than that of the current distribution shown in FIGS. 7 and 8, and the distribution curve of the potential distribution is broader. The relative relationship between the peak heights shown in FIG. 10 indicates that the potential peak height may fluctuate greatly due to the inhomogeneity of the ground 1 in the potential method.

Further, from the current distribution and the potential distribution obtained in FIG. 7, FIG. 8, FIG. 9, and FIG. 7, 8, 9, and 1 by fitting by the multiplication method.
The peak position in the current distribution of 0 was estimated. The peak position obtained in this manner is defined as an estimated water leakage position. The deviation between the estimated leak position thus obtained and the leak positions set as 0 m, 1 m, 2 m, 3 m, 4 m, and 5 m in the numerical calculation, that is, the estimated leak position accuracy was calculated.

[0054]

(Equation 6)

FIG. 11 is a diagram showing the result. The vertical axis is the estimated leak position obtained by the fitting, and the horizontal axis is the leak position set in the numerical calculation. FIG. 11A shows a result obtained when the current method of the present invention is used, and FIG. 11B shows a result obtained when the potential method is used. 11, the estimated leak location x ₀ obtained by fitting using the above equation (2) is closer to the set water leakage position in the numerical calculation, leak detection can detect better water leakage position It can be said that the method.

In the above formula, x is an arbitrary position (independent variable) between the point electrode 7 at the 0 m position and the point electrode 7 at the 5 m position.
Are shown, _{x 0} denotes the estimated leak position, G (x), the current value or potential, a, b are constants.

As shown in FIG. 11 (a), the estimated leak position determined by using the current distribution according to the present invention is within about 40 cm at the electrode interval of 5 m regardless of the homogeneous ground and uneven ground. It can be seen that can be determined by: Therefore, from the result shown in FIG.
Considering that the interval is set, it can be said that according to the water leak detection method of the present invention, the leak position can be determined with an error within approximately 1/10 of the electrode interval.

On the other hand, as shown in FIG. 11B, in the potential method using the potential distribution,
An error close to 1 m occurs at random at the maximum, and it is understood that the detection accuracy is greatly affected by the specific resistance distribution of the ground 1 as compared with the case where the leak location is determined using the current distribution as in the present invention. .

(2) Investigation of the effect of electrode loss In the potential method, even if one of the point electrodes 7 has a defect and the potential measurement at the point electrode 7 becomes impossible,
It does not affect the potential distribution in the ground. However, when the current method is used as in the present invention, when the defect of the point electrode 7 occurs, the leakage current stops flowing to the point electrode 7, and there is a point where the current distribution between the point electrodes 7 cannot be measured at all. Will happen.

FIG. 12 is a diagram showing the results of an experiment conducted by numerical calculation on the current distribution when a defect occurs in the point electrode 7 used in the present invention. In FIG. 12, the results when there is no loss of the point electrode 7 are shown by (●), and the results when the loss of the electrode occurs at 0 m are shown by (△).
The result when the point electrode 7 is missing at the position of m is indicated by (□). In the numerical calculation experiment of the loss of the electrode 7 by the numerical calculation, the water leakage position was assumed to be 0 m. Further, in FIG. 12, regarding the current distribution when the point electrode 7 at the 0 m point is lost, the current that should originally flow at the 0 m position is distributed to the point electrodes 7 on both sides of −5 m and 5 m. It is shown that the intensity of the plot indicated by ()) is higher than the other plots.

As shown in FIG. 12, the plots for the case where there is no loss (●) and the case where the point electrode 7 at 10 m is missing (□) are the same as those of FIG. The plot completely overlaps with the plot in the case where there is no loss, and it can be seen that the loss of the point electrode 7 at a position away from the water leakage position has almost no influence on the determination of the water leakage position.

However, the point electrode 7 at the water leakage position
Since the point electrode 7 to which a peak in the current distribution is to be lost is missing, no peak in the current distribution is obtained as shown by the plot (△) shown in FIG. Actually, instead of directly estimating the water leakage position from the actually obtained peak of the current distribution, it is considered that the estimated water leakage position is obtained by fitting using the equation (1) or the like. Although the error may slightly increase with respect to the estimated leak position even when the leak is not obtained, the leak is determined by using a conventionally known technique such as a fitting technique such as a least squares method or a curve interpolation method using a spline function. Location estimation is possible.

(3) Simultaneous Detectability of Plural Water Leakage Locations When Water Leakage Simultaneously Occurs Using the present invention, a numerical calculation experiment is performed on the water leaking position detection performance when two water leakage locations occur simultaneously. This was added to the study. Regarding the conditions such as the homogeneous ground and the heterogeneous ground of the ground 1 used for the numerical calculation, and the arrangement of the point electrodes 7,
(1) The conditions were the same as those described in the examination of the water leak position detectability.

FIGS. 13 and 14 show that when there are a plurality of water leaking points, the distances between the plurality of water leaking points are separated at a predetermined peak width of the current distribution. FIG. FIG. 13 is a diagram showing a result of numerical calculation performed on a homogeneous ground, and FIG. 14 is a diagram showing a result of numerical calculation performed on a heterogeneous ground.

In the numerical calculation, the first leak is fixed as occurring at 0 m, and the second leak position is changed to −25 m every 5 m with respect to the point electrode 7 at the position of 0 m by 5 m. went. Also, the leakage current at 0 m is 1 A
The numerical calculation was performed on the assumption that a current of 0.5 A flows at the second water leakage position. As shown in FIG. 13, in the case of the homogeneous ground, when the second water leakage occurs at a position of 5 m, the peak separation is insufficient, but the leakage point at a position of 10 m or more is clear. It can be seen that an excellent peak separation was achieved. -5
In the water leak at the point m, the peak is not clearly separated, but as a result of the water leak at the position of -5 m, the peak at the position of 0 m is shown to be broad.

In FIG. 14, which shows the result of performing the same numerical calculation on the heterogeneous ground, similarly to the result shown in FIG. 13, the fact that the current peak of the water leakage at the -5 m position is not separated, It can be seen that substantially the same result as that of the homogeneous ground shown in FIG. 13 is obtained. That is, according to the present invention, in the case of the point electrodes 7 arranged at 5 m intervals, both of the homogeneous ground and the heterogeneous ground,
It can be seen that if two or more poles are separated, peak detection can be performed even when water leaks at two locations.

As shown in FIGS. 13 and 14, -5 m
When the second water leakage occurs at the position, the current peak cannot be separated from the current peak at the first water leakage position on the homogeneous ground or the heterogeneous ground. However, FIG.
As shown in FIG. 14 and FIG. 14, the current peak at the 0 m position is broadened due to the peak of the current distribution caused by water leakage at the −5 m position. As described in FIG. 15, depending on the intensity of the leakage current generated in actual water leakage, the specific resistance distribution including the low water-permeable structure 6 of the ground 1 at the site is measured in advance, so that the current peak due to the water leakage is measured. If the width can be predicted, it is possible to separately separate overlapping waveforms by using a known waveform separation technique such as deconvolution, or to apply the above equation (2) according to the broadening of the peak width. By combining the current peaks and performing the least squares method, it is also possible to obtain the estimated leak positions of the first leak position and the second leak position.

FIG. 15 shows the result of a numerical calculation experiment on the detectability of the second water leakage position when the intensity of the leakage current at the second water leakage position is changed. In FIG.
The first water leakage position is set to the 0 m position, and the second water leakage position is set to -2.
The position was fixed at 0 m. In FIG. 15, FIG.
As in 4, a current of 1 A flows at the first leak position (0 m), and the intensity of the leak current flowing at the second leak position (−20 m) is changed between 0.001 and 0.5 A to perform a numerical calculation. went. In FIG. 15, since the current scale is wide,
The vertical axis is shown as a logarithmic scale. FIG. 15 shows how much current flows at the second water leakage position, and from which a current peak caused by the second water leakage can be determined from the current distribution continuing from the first water leakage position.

As shown in FIG. 15, it can be seen that the leakage current at the second water leakage position at −20 m can be observed as a peak even if it decreases to about 0.001 A. Actually, background noise or the like at the time of measurement is generated. Therefore, when a current of about 0.001 A flows as a leakage current at the second water leakage position, as shown in FIG. Although it cannot be said that can be separated, it is easier to measure 1 mA by current measurement and less noise than to measure 1 mV in potential measurement. Therefore, the current method of the present invention can be used from this point of view. It can be said that the leak detection device and the leak detection method that were used can determine the leak position with sufficiently high accuracy.

Further, in the present invention, a third electrode for separately measuring the specific resistance of the ground 1 is disposed in the ground, and the potential distribution is measured using the electrode disposed below the ground 1. Then, it is also possible to measure a change in specific resistance due to a change in groundwater level or the like in the ground 1 in advance. Using the resistivity distribution obtained in this way, the peak width and the like in the current distribution are calibrated, and the water leak position can be detected with higher accuracy.

Although the present invention has been described using one-dimensional leakage position determination for convenience of explanation, in an actual waste disposal site, three-dimensional data obtained by adding a current distribution to two-dimensional data on the leakage position is used. It is needless to say that the use of the least squares method in the above can detect a leak and determine a leak position in a plane such as a waste disposal site. Further, the expression (2) used in the embodiment of the present invention.
Is only used for illustrative purposes, and if it is a function showing a linear function or more attenuation of the distance from the center point electrode 7 in the center symmetry with respect to the water leakage position, an exponential function, a quadratic function Of course, it is possible to use a function that decays with a higher order polynomial.

[0072]

According to the present invention, the infiltration of sewage contaminated by discarded waste into the ground is quickly detected, the leakage is detected by using the electric current method, and the ratio of ground and waste is detected. Water leakage detection device that is less affected by resistance distribution and less affected by noise than the potential method, enables accurate determination of water leakage position, and does not reduce the water shielding of the water shielding part Can be provided.

According to the present invention, it is possible to detect water leakage and determine a leakage position with high accuracy by using current distribution without using current measuring means as many as the number of point electrodes.
It is possible to provide a water leakage detection device that is hardly affected by measurement noise, and that is more inexpensive and operable.

According to the present invention, it is also possible to correct the influence of fluctuations in groundwater level and the like on the ground, and to plot the leakage position with respect to the distribution of K and to interpolate using a spline function or the like. A high-precision water leakage detection device capable of estimating a water leakage position can be provided.

According to the present invention, there is provided a water leakage detecting device capable of measuring the current distribution in the water shielding portion at a time, detecting the water leakage more quickly and accurately, and determining the position of the water leakage. it can.

According to the present invention, the infiltration of sewage contaminated by dumped waste into the ground is promptly detected,
Detects water leakage using the current method and is less affected by the resistivity distribution of the ground and waste, and is less affected by noise than the potential method. In addition, it is possible to provide a water leakage detection method that does not lower the water blocking of the water blocking section.

According to the present invention , water leak detection and leak position determination can be performed with high accuracy using current distribution without using current measuring means by the number of point electrodes, and the specific resistance distribution,
It is possible to provide a water leakage detection method that is hardly affected by measurement noise, and that is inexpensive in construction and construction costs.

According to the present invention, it is also possible to correct the effect of fluctuations in groundwater level and the like on the ground, and to plot the water leakage position against the distribution of K and to interpolate using a spline function or the like. A water leak detection method capable of estimating a water leak position can be provided.

According to the present invention, there is provided a water leakage detecting method capable of measuring the current distribution in the water shielding portion at one time, detecting the water leakage more quickly and accurately, and determining the position of the water leakage. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a waste disposal site to which the present invention is applied.

FIG. 2 is a longitudinal sectional view showing the configuration of the water leakage detection device according to the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a configuration of a water leakage detecting device according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an electrode arrangement of the water leakage detection device of the present invention.

FIG. 5 is a diagram showing a state in which water leakage has occurred in the water leakage detection device according to the first embodiment of the present invention.

FIG. 6 is a view showing a state where water leakage has occurred in the water leakage detection device according to the second embodiment of the present invention.

FIG. 7 is a diagram showing water leak position detection using current distribution in the present invention.

FIG. 8 is a diagram showing water leak position detection using a current distribution in the present invention.

FIG. 9 is a graph showing water leak position detection using a potential distribution.

FIG. 10 is a graph showing water leak position detection using a potential distribution.

FIG. 11 is a diagram showing the accuracy of an estimated water leakage position.

FIG. 12 is a diagram showing a current distribution when a defect occurs in a point electrode 7 used in the present invention.

FIG. 13 is a diagram showing peak separability when there are a plurality of leak locations.

FIG. 14 is a view showing peak separability when there are a plurality of leak locations.

FIG. 15 is a diagram showing detection of a second water leakage position based on the intensity of a leakage current at the second water leakage position.

FIG. 16 is a view showing water leak detection by a conventional potential method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ground 2 ... Water shielding part 3 ... Waste 4 ... Sand layer or earth covering 5 ... Water shielding sheet 6 ... Low water permeability structure 7 ... Point electrode 8 ... Concave electrode 9 ... Power supply 10 ... Electrometer 11 ... Ammeter 12 ... Conductive wire 13 ... Electrode switching means 14 ... Control means 15 ... Leakage point 16 ... Leakage current path 17 ... Leakage current path 18,19,20 ... Leakage current path 21 ... Reference electrode 22 ... Ammeter I ... Leakage current Ir ... Reference current I _{1 to} I ₅ ... leakage current

──────────────────────────────────────────────────の Continued on front page (72) Inventor Tsutomu Tanaka 1-20-10 Toranomon, Minato-ku, Tokyo (72) Inventor Toshio Yoshikawa 1-20-10 Toranomon, Minato-ku, Tokyo (72) Inventor Kanamaru Shinichi 1-20-10 Toranomon, Minato-ku, Tokyo (72) Inventor Yukio Sakai 1-11-5 Kudankita, Chiyoda-ku, Tokyo Inside Basic Ground Consultants Co., Ltd. (72) Inventor Shigeru Miki Kudan, Chiyoda-ku, Tokyo 1-11-5 Kita Basic Ground Consultants Co., Ltd. (56) References JP-A-11-248589 (JP, A) JP-A-11-352004 (JP, A) JP-A-4-359130 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 3/16

Claims (6)

(57) [Claims] 1. A recess in the ground and on the ground along the recess
A water-blocking structure comprising a water-blocking section laid and subjected to water-blocking
Leakage to detect water leakage from the recess into the ground
A water detecting device, comprising: a plurality of electric power sources arranged on the ground adjacent to the water shielding portion.
A pole; a recess electrode disposed in the recess; and a power supply for flowing a current between the point electrode and the recess electrode.
And a leakage current caused by water leakage from the recess to the ground.
Current measuring means for measuring, electrode switching means, different leakage between the recessed electrode and each point electrode
Control means for forming a current pathWhen, A reference electrode, The leakage current flowing in the leakage current path
Detects water leaks through the distributed current, The leak point
The detection of leakage current, the recessed electrode and the reference electrode,
The following equation (1) with the current flowing betweenTo do with the ratio (K) given byFeatures
Leak detector(In the equation (1), I is a leakage current,
Ir is a current flowing between the concave electrode and the reference electrode.
Is shown. ). 2. The apparatus according to claim 1, wherein the electrode switching means switches and connects the recessed electrode and one of the plurality of point electrodes to form the plurality of leakage current paths. Water leak detection device. 3. The water leakage detection device according to claim 1, wherein said electrode switching means forms a plurality of said leakage current paths in parallel between said recessed electrode and said point electrode. (4) A depression in the ground and on the ground along the depression
Impermeable structure with laid and impervious treatment
Leakage to detect water leakage from the recess into the ground
A method for detecting water, comprising: a plurality of power points disposed on the ground adjacent to the water shielding portion;
A pole, a recess electrode disposed in the recess, and the point electrode;
A power source for passing a current between the recess electrodes;
The leakage current caused by water leakage from the ground to the ground
Measuring means, electrode switching means, and electrode switching
Control device for controlling means
When the water leaks from the impermeable part to the ground,
Multiple leakage current paths are formed between each point electrode.
The leakage current flowing through the plurality of leakage current paths
Measured in the area along the line, the leakage current flowing through the leakage current path
Detects water leaks through current distributionAnd The water leak detection device further includes a reference electrode,
The detection of the water spot is determined by the leakage current, the recess electrode and the reference current.
Equation (1) below with the current flowing between the poles (Equation 2) Using the ratio (K) given by
(In the equation (1), I is a leakage current,
Ir is a current flowing between the concave electrode and the reference electrode.
Is shown. ). 5. according to the plurality of the leakage path to claim 4, characterized in that for driving the electrode switching means so as to form between one of the recess electrode and a plurality of said point electrode Water leak detection method. 6. A plurality of the leakage current path, leak detection according to claim 4, characterized in that for driving the electrode switching means so as to form in parallel between the point electrode and the recess electrode Method.