JP3050654B2 - Water leak position detection method using current vector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for electrically detecting a water leakage position in a water storage tank, a waste disposal site, and other water-blocking structures having a water-blocking layer.

[0002]

2. Description of the Related Art When constructing a water storage tank or a managed final disposal site, an artificial water-impermeable membrane (a vinyl sheet, a rubber sheet, etc.) such as a synthetic resin is used as a material of a water-blocking work for forming a water-blocking layer. When used, it is possible to construct a highly water-impervious structure at a low cost and in a short period of time, compared to the case of construction using concrete lining. Even when constructing a managed final disposal site, there is a tendency to increase the number of cases where a water blocking method using a thin artificial water-impermeable membrane (hereinafter referred to as a sheet) of 1 mm to 2 mm is adopted.

However, as a drawback of the sheet-based water-blocking method, when the sheet is damaged for some reason and a hole is formed in the water-blocked structure, the sheet itself is fragile as a construction material, so that the sheet itself is fragile as a construction material. Leakage from materials will gradually increase, especially in controlled final disposal sites, etc., in order to prevent contamination of the surrounding environment to a minimum, locate holes in the sheet, that is, damage locations of the impermeable layer as much as possible. It is necessary to find and repair the sheet immediately, and a technique for accurately detecting the damaged position of the sheet, that is, the leak position is required.

As such an electric leak position detecting method, a method of measuring the distribution state of the potential difference in the impermeable structure and grasping the leak position by the applicant of the present invention (Japanese Patent Laid-Open Publication No. Hei 1 (1990) -1990).
No. 178843) or a method of appropriately moving an electrode into which a current is inserted in a water-blocking structure, and grasping the position of water leakage from the direction of the current flowing from the electrode (No. 81 of the Geophysical Exploration Society of Japan).
Proceedings of the Annual Scientific Lecture Meeting, November 1999).

[0005]

However, in the former method, when performing high-accuracy measurement, the number of measurement points increases because the distribution of the potential is finely grasped. Since it is necessary to provide a reference point and determine the potential from the potential difference between this point and each measurement point, it is necessary to electrically connect each measurement point to the reference point, and it is not possible to wirelessly connect each measurement point There is. In the latter method, it is necessary to move the electrode into which the current is inserted, so there is no problem when the conductive medium substance accommodated in the impermeable structure is a fluid liquid. Since the electrode cannot be easily moved in the case of waste or the like, there is a decisive drawback in that the medium cannot be used when the medium substance contained in the facility to be measured is a solid such as waste.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, to enable accurate detection of a leak position with relatively few measuring points, and to store a fluid substance such as water by fixing a measuring point. It is an object of the present invention to provide a method for detecting a leak position, which can be applied to a case where a non-flowable substance such as waste is contained in the same manner.

[0007]

According to the present invention, an internal electrode for voltage application is fixedly installed inside a water impermeable structure, and an external electrode for voltage application is buried and installed in the ground outside the water impermeable structure. Installing current vector measuring means at a plurality of predetermined positions inside the water-blocking structure, applying a voltage between the voltage-applying internal electrode and the voltage-applying external electrode, and applying the voltage to the predetermined position. Is measured by the current vector measuring means, and the leakage position is detected from the distribution of the magnitude of the current and the direction of the current.

[0008]

[Function] In a water-blocking structure having a water-blocking layer made of an electrically insulating material, an internal electrode is fixedly installed inside a water-blocking structure containing a conductive material, and is fixedly installed outside the water-blocking structure. When a voltage is applied between the external electrode and the external electrode, a current flows between the internal electrode and the external electrode through the hole if a hole is formed in the electrical insulation that is the water-impervious layer. Since the direction and relative magnitude of the current at each point in the structure are determined by the positional relationship between the internal electrode and the hole, measure the magnitude and direction of the current at two or more points in the impermeable structure. Thereby, the position of the hole generated in the impermeable layer, that is, the water leakage position can be detected.

[0009]

FIG. 1 is a cross-sectional view of a water-impervious structure 1 when the method of detecting a water-leakage position based on a current vector according to the present invention is carried out. FIG. 2 is a top view of the same.

In FIG. 1, a water-blocking structure 1 is usually formed as a rectangular opening formed by shaping a valley-shaped ground and having a trapezoidal vertical cross section, and an electrically insulating artificial water-impermeable membrane (hereinafter referred to as an inner surface) on its inner surface. (Referred to as a sheet) 2 is laid as a waterproof layer. A conductive material 3 such as water or waste is accommodated in the impermeable structure 1.

As shown in FIG. 1, a conductive material 3 covered with an electrical insulator (in this case, a material accommodated inside the water-blocking structure 1) and a conductive material 4 outside the conductive material 3 (this material). In the case where a voltage V is applied between the inner conductive material 3 and the inner electrode 5 for applying a voltage (current insertion) and the outer electrode 6 between the inner electrode 5 and the outer electrode 6, a hole 7 must be formed in the sheet 2 covering the inner conductive material 3. For example, a current flowing through the sheet 2 or a small leakage current flowing along the surface of the sheet 2 and an electric capacitance component (capacitance) generated by the sheet 2 being an insulator.
Current does not flow except for the capacitive current flowing due to the above, and if the frequency of the applied voltage V is low, almost no capacitive current flows. Therefore, it can be generally considered that no current flows. Is open, current flows through this hole 7. As shown in FIG. 2, the current passing through the hole 7 conducts the conductive material 3 inside the water-blocking structure 1, and the current flows between the hole 7 and the internal electrode 5 inserted into the conductive material 3. Flow along the lines of electric force created by the The lines of electric force are affected by the shape of the conductive material 3 covered with the sheet 2 which is an electrical insulator. If these are known, they are determined by the positional relationship between the hole 7 and the internal electrode 5. The position of the hole 7 formed in the sheet 2 is detected by measuring the current vector and grasping the direction and magnitude of the current flowing at two or more points.

FIG. 3 is a block diagram of an example of an apparatus for implementing the method for detecting a water leak position using a current vector according to the present invention.

As shown in FIG. 3, the current vector measuring device 8
Are fixedly installed at predetermined intervals inside the water-blocking structure 1 that has been subjected to water-blocking work with the sheet 2 that is an electrical insulator, and the internal electrodes 5 for voltage application are placed inside the water-blocking structure 1 and The external electrode 6 for voltage application is buried and installed in the ground near the outside of the water-blocking structure 1.

An alternating voltage of a low frequency constant voltage is applied between the internal electrode 5 and the external electrode 6 from an AC constant voltage power supply 10 installed in the measurement center 9.

The applied voltage may be either DC or AC in principle, but when actually applied to a field, a ground current flows in the ground and escapes from this influence. The measurement accuracy improves when the signal is changed to AC. When an electrode is placed in waste or on the ground, a polarization potential is generated. To avoid this effect, it is preferable to use an alternating current as a signal power supply.

In this state, if there is no damage to the sheet 2, almost no current flows between the internal electrode 5 and the external electrode 6. However, when the sheet 2 is damaged, that is, when the hole 7 exists, a current flows between the internal electrode 5 and the external electrode 6 through the hole 7 as described above.

The magnitude and direction of this current are determined by the impermeable structure 1
The measurement is performed by the current vector measuring devices 8 installed at predetermined intervals in the inside, the measurement data measured by each current vector measuring device 8 is transmitted to the measurement center 9, and processed by the arithmetic circuit 11 provided in the measurement center 9. The hole 7 generated in the sheet 2
, That is, the water leakage position. The detected result is C
The image is displayed by an output device 12 such as an RT or XY plotter.

Further, the timing signal generating circuit 13 controls the on / off of the AC constant voltage power supply 10 and applies an applied voltage in order to avoid the influence of the earth current on the ground and the influence from the polarization potential (almost a direct current component) as described above. Since a low-frequency AC power source is used as the power source, since the direction of the flowing current changes by 180 degrees every time the polarity of the power source changes, the direction of the current vector is measured while synchronizing with the polarity of the power source. It is necessary to send a phase signal to the AC constant voltage power supply 10 and the current vector measuring device 8 at the same time so that both are synchronized.

Further, in this example of the apparatus, the measurement control and the transfer of the measurement data between the measurement center 9 and the current vector measuring device 8 are performed by a wireless system. Generates a modulation signal for instructing the current vector measuring device 8 to measure the current vector, radiates this to the air through the antenna 15, and receives the measurement data signal from the current vector measuring device 8 by the antenna 15. Then, it is demodulated and sent to the arithmetic circuit 11.

FIG. 4 is an external view of a measuring electrode in the current vector measuring device 8 and a circuit block diagram.

Measurement electrode 16 of current vector measuring device 8
Are formed by arranging two sets of electrode elements 18x and 18y for measuring currents in the X and Y directions between the parallel electrode holders 17 in directions orthogonal to each other, and the communication circuit 1
9 receives and demodulates the control signal sent from the measurement center 9, and the current vector measurement circuit 20 synchronizes with the phase signal included in the control signal sent from the measurement center 9 while synchronizing with the X direction and the Y direction. By measuring the magnitude and polarity of the current and synthesizing these measured values, the data is detected as data of the magnitude and direction of the current vector at the position where the current vector measuring device 8 is placed, and the measurement center 9
Is transmitted by radio from the antenna 21 to the measurement center 9 side as a signal modulated by the communication circuit 19 according to the request from the communication circuit 19.

A solar cell 22 is used as a power source of the current vector measuring device 8, and the power generated by the solar cell 22 is charged to a secondary battery 23 and supplied to each circuit of the current vector measuring device 8 when necessary. However, the power supply circuit 24 performs this control.

In the conventional method for detecting a water leak position, it is difficult to wirelessly transfer the data measured by the measuring means, and the measuring means (measurement internal electrode) installed in the water-blocking structure and the measurement result It is necessary to connect with the arithmetic processing means by wiring for transfer of measurement data, and in the case of application in a final disposal site during landfill, there was a problem that wiring becomes an obstacle to work, As in this device example, the data transfer between the current vector measuring device 8 and the measurement center 9 is performed by a wireless method, and the power vector system using the solar cell 22 is employed.
And the measurement center 9 can be completely cordless.

When detecting the position of the hole 7 in the impermeable structure 1, that is, the damaged position of the sheet 2, first, a control signal is sent from the timing signal generating circuit 13 to the AC constant voltage power supply 10 to turn on the AC constant voltage power supply 10. By doing so, a low-frequency constant voltage alternating current is applied between the internal electrode 5 and the external electrode 6. Further, the phase signal is transmitted to the AC constant voltage power supply 10 and the current vector measuring device 8 to synchronize them. Next, each current vector measuring device 8 is controlled by the control from the measuring center 9 side.
Is specified, and the measurement data in each current vector measuring device 8 is sequentially read and stored in a storage circuit (not shown) in the arithmetic circuit 11. When all the data of the magnitude and direction of the current vector relating to all the current vector measuring devices 8 are collected, the arithmetic circuit 11 calculates the position of the hole 7 in the impermeable structure 1, that is, the damaged position of the sheet 2, and as a result, To CR
It is displayed on an output device 12 such as a T or XY plotter.

Note that all the current vector measuring devices 8
In calculating the position of the hole 7 in the impermeable structure 1, that is, the damaged position of the sheet 2, from the data of the magnitude and direction of the current vector at, the current component flowing in the vertical direction and the capacitive current are not related to the position measurement. Therefore, it is necessary to eliminate the current component as a background before the calculation of the position of the hole 7, and to extract measurement data having a scalar amount of current within a standard deviation, and obtain an average value in each of the X and Y directions. By subtracting this as a background in the X and Y directions from all measurement data, current components irrelevant to position measurement are eliminated to enable accurate position detection.

FIG. 5 is a diagram showing an example of an experiment for detecting a water leak position. The position indicated by a circle in FIG. 5 corresponds to the result of detecting the damaged position of the sheet 2. In this experimental example, the measuring electrode 16 was fixedly installed at every 50 m at the bottom of the water-blocking structure 1 subjected to the water-blocking work with the sheet 2, and the internal electrode 5 was marked with a black circle (150, 0). After setting a dummy hole 25 indicated by an asterisk at approximately (125, 125) of the sheet 2 of the impermeable structure 1 and measuring the current vector flowing through each measurement electrode 16, the background is erased. X-Y
The output is displayed by a plotter, and the damaged position of the sheet 2 is detected very accurately.

Next, the principle of calculating the water leakage position based on the current vector will be described. As a method of finding the damage position, it is possible to determine the damage position by grasping the overall state of the current flowing in the disposal site from the data of the current vector measuring device arranged in a mesh shape and the position of the internal electrode. First, from the magnitude and direction of the current at each measurement point, find out the approximate location of the break point between the measurement points, and then determine the final position from the data of the four measurement points surrounding the break point. We use a method to figure out. This has the advantage that the number of calculations is small and the calculation time can be reduced.

As shown in FIG. 5, it is determined which of the measurement points has the broken position. As can be seen from FIG. 5, the current vector is large around the broken position, and the current value is large. From this, a point above a certain value is selected. For example, a point not less than the standard deviation and not near the internal electrode. Since the current also increases near the internal electrode as shown in FIG. 5, the internal electrode is not erroneously selected as a damaged position under the conditions shown in FIG. Considering that there is a broken position in the vector direction of the selected point, three points in the direction indicated by the selected point and the current vector of the selected point are selected, and an operation for calculating the final position from a total of four measured values is performed. .

Next, a method of calculating the final position will be described. As shown in the explanatory diagram of FIG. 7A, when the current I flows from one point of the uniform conductive medium material in all directions, the current i when the current I is received in the area ΔS at the point of the distance r is (1 ).

In the case of the hemisphere shown in FIG.
In the case where no current flows below the point where the current I flows, the current i ′ when receiving the area ΔS at the point of the distance r is twice the current i shown in the equation (1).

In the same state as the case where it is set on the bottom surface of the hemisphere, the distance from the point at which the currents i1, i2 and the current I measured at the two points A and B shown in FIG. r1, r2
And the following relationship is established.

From the ratio of these two equations, Since r1 and r2 are positive, equation (6) is obtained.

Assuming that the distance between A and B is H, r1 is given by equation (7).

Therefore, the measuring electrodes 16A, 16A in FIG.
The current vectors measured at 16B, 16C, and 16D are Ia, Ib, Ic, and Id, respectively, and the x and y components of each current vector are Iax, Iay, Ibx, Iby, Icx, Icy, and Icy.
dx and Idy. The distances from the measurement electrodes 16A to the holes 7 (corresponding to the damaged positions of the sheet 2) are X and Y, and the distances between the measurement electrodes 16A to 16B, 16B to 16C, 1
6C to 16D and 16D to 16A are set to H (constant).

First, the measuring electrodes 16A, 16B, 16D
Xa, Ya which are x, y components obtained from
From equation (7), Similarly, the x and y components obtained from the measurement electrodes 16A, 16B and 16C are Xb and Yb, and the measurement electrodes 16B and 16C,
The x and y components obtained from 16D are Xc and Yc, and the measuring electrode 1
Xd and Yd are x and y components obtained from 6C, 16D and 16A, respectively.
Then, equations (10) to (15) are obtained.

By taking a weighted average from the scalar quantity | I | of each current vector I at the center in consideration of noise and the like, the measurement electrode 16A and the hole 7 are finally obtained.
X and Y can be obtained as shown in Expressions (16) and (17).

These operations are performed by a microcomputer (not shown) built in the operation circuit 11,
The damaged position of the sheet 2 is detected as an absolute position from any of the fixedly installed measurement electrodes 16 (the measurement electrode 16A in the case of the above description).

The electrode 18 of the measurement electrode 16
The numbers x, 18y are, as in the above description, FIG.
It is sufficient that three or more besides 2 to 4 as shown in the explanatory diagram of FIG. 9A, and the current vector can be calculated theoretically as shown in FIG. 9B and FIG. 9C. Any arrangement may be used as long as it has a certain shape.

Although the above embodiment has been described as an example of obtaining a current vector on a plane, it is necessary to measure the current vector three-dimensionally, for example, when the bottom surface of a seepage control is oblique. In this case, it is possible to detect the damaged position of the sheet 2 by performing the measurement so that the measurement cross sections of the above-described embodiment are orthogonal to each other.

Although the precision is further reduced, the position of water leakage can be obtained from the two measuring electrodes 16A and 16B as shown in FIG. 10 from the following equations (18) and (19). This is effective when there is a water leakage position outside the range where the current vector measuring device is arranged.

The y component obtained from the measurement electrode 16A is And the y component obtained from the measurement electrode 16B is Thus, by taking a weighted average from the scalar quantity, the equation (19) is obtained.

[0042]

As described above, according to the present invention,
The internal electrode for voltage application is fixedly installed inside the impermeable structure,
An external electrode for voltage application is buried and installed in the ground outside the impermeable structure, current vector measuring means is installed at a plurality of predetermined positions inside the impermeable structure, and the internal electrode for voltage application and the A voltage is applied between the external electrode for voltage application, the magnitude and direction of a current generated at the predetermined position by the voltage are measured by the current vector measuring means, and the water leakage position is detected from the measurement result. Therefore, it is possible to detect the leak position with high accuracy by using relatively few measuring points, and to fix non-fluid substances such as waste even when storing fluid substances such as water by fixing the measurement points. The same can be applied to the case in which it is performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a water-blocking structure when a method for detecting a water-leakage position by a current vector according to the present invention is performed.

FIG. 2 is a top view of a water-blocking structure when the method of detecting a water leakage position by using a current vector is also performed.

FIG. 3 is a configuration diagram of an example of an apparatus that implements a method for detecting a water leak position based on a current vector according to the present invention.

FIG. 4 is an external view of a measuring electrode in the current vector measuring device and a circuit block diagram of the current vector measuring device.

FIG. 5 is a diagram showing a measured current vector in an experimental example of water leak position detection according to the present invention.

FIG. 6 is a diagram showing conditions for selecting a broken position near an internal electrode in FIG. 5;

FIG. 7 is a diagram illustrating a method of calculating a water leakage position based on a current vector.

FIG. 8 is a diagram showing a specific method of obtaining a water leakage position using a current vector.

FIG. 9 is a diagram showing another example of the arrangement of measurement electrodes.

FIG. 10 is a diagram showing another example of a specific method of obtaining a water leakage position using a current vector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Water-blocking structure 2 Artificial water-impermeable film (sheet) 3 Conductive substance 4 Conductive substance (soil) 5 Internal electrode 6 External electrode 7 Hole 8 Current vector measuring instrument 9 Measurement center 10 AC constant voltage power supply 11 Arithmetic circuit 12 Output device 13 Timing signal generation circuit 14 Communication circuit 15 Antenna 16, 16A, 16B, 16C, 16D Measurement electrode 17 Electrode holding unit 18x, 18y Electrode 19 Communication circuit 20 Current vector measurement circuit 21 Antenna 22 Solar cell 23 Secondary battery 24 Power supply circuit 25 Pseudo hole H Distance between electrodes I, Ia, Ib, Ic, Id, Iax, Iay, Ibx, Iby, Icx,
Icy, Idx, Idy Current i, i ', i1, i2 Current r, r1, r2 Distance V AC voltage X, Xa, Xb, Xc, Xd Distance Y, Ya, Yb, Yc, Yd Distance ΔS Area

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-29830 (JP, A) JP-A-1-178843 (JP, A) JP-A-2-501767 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G01M 3/40

Claims (1)

(57) [Claims] 1. A method for detecting a water leakage position of a water-blocking structure provided with a water-blocking layer made of an electrically insulating material and containing a conductive substance such as water or waste, comprising the steps of: An internal electrode for voltage application is fixedly installed inside, and an external electrode for voltage application is buried and installed in the ground outside the impermeable structure, and current vector measuring means is provided at a plurality of predetermined positions inside the impermeable structure. Is installed, a voltage is applied between the voltage-applying internal electrode and the voltage-applying external electrode, and the magnitude and direction of a current generated at the predetermined position by the voltage are measured by the current vector measuring means. A method for detecting a water leak position using a current vector, wherein the water leak position in the water impermeable structure is detected from the measurement result.