JP2000258279A - Method for testing impervious sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a status equivalently at the time when an electrode having a large area is laid even if the area of an electrode is small by making an electrode to be arranged on one side of an impervious sheet in a circular form of a metallic wire. SOLUTION: For example, a impervious sheet such as synthetic resin sheet to be laid in a terminal disposal area is tested for breakage e.g. by using a plurality of electrodes 10 arranged two-dimensionally on the lower side of the impervious sheet and measuring a current flowing from an electrode provided on the other side of the impervious sheet to a selected electrode 10. The electrode 10 is formed in a circular shape such as ring of one to several meters in diameter for example, and a high potential can be obtained in the inside of the electrode 10, showing the same effect as that of a plate electrode having the same external shape. In addition, the electrode 10 of the circular shape is apt to be deformed different from the plate electrode, so fear for breaking the impervious sheet is small even if the ground varies because of earthquake, etc. The electrode 10 has a structure that two metallic wires are connected as to shortcircuit two points facing inwardly with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a seepage control sheet in a controlled final disposal site constructed by laying a seepage control sheet made of a synthetic resin or synthetic rubber sheet or asphalt.

[0002]

2. Description of the Related Art Conventionally, in an artificially managed final disposal site using a water-impervious sheet, the water-impervious sheet may be damaged by cracks or the like, and contaminated liquid in the disposal site may leak. If water leakage occurs, pollution problems such as groundwater pollution will occur.Therefore, it is necessary to inspect the impermeable sheet periodically, and if the impermeable sheet is damaged, it is necessary to detect the damaged area and perform appropriate repairs. is there.

[0003] In such a method of inspecting a broken portion of the water-impervious sheet, an electrode for applying a voltage is laid on the upper side of the water-impervious sheet, and a plurality of plate-like measurement is performed below the water-impervious sheet. A configuration in which electrodes are laid is used. In this inspection method, a voltage is applied between the upper electrode of the impermeable sheet and the selected electrode below the impermeable sheet, and the current flowing through the selected lower electrode is measured to determine the soundness of the impermeable sheet. Has been inspected.

In this inspection method, if a break occurs in the impermeable sheet, a maximum current flows to the lower electrode closest to the damaged portion. Therefore, it is possible to detect a damaged portion of the impermeable sheet in two-dimensional coordinates from the distribution of current flowing through each lower electrode.

FIG. 4 is a diagram showing the configuration of the above-mentioned conventional inspection system. A plate-like first electrode 2 is provided above the water-impervious sheet 20.
1, and a plurality of two-dimensional plate-shaped second electrodes 22 are arranged below the water-impervious sheet 20. First and second
Each of the electrodes 21 and 22 has a square or rectangular shape. The first electrode 21 is connected to one of the power sources 23. An electrode switch 24 is arranged between the plurality of second electrodes 22 and the current detection circuit 25, and one of the plurality of second electrodes 22 is selected by the electrode switch 24 and is supplied to the current detection circuit 25. Connected. On the other hand, all the unselected second electrodes 24 are connected to the ground side of the power supply 23. As a result, the current flowing through the selected second electrode 22 is measured by the current detection circuit 25. In this case, if the power supply 23 is a DC power supply, the current detection circuit 25 uses a DC ammeter, and if the power supply 23 is an AC power supply, an AC ammeter is used.

[0006] Regarding the arrangement of the first and second electrodes 21 and 22, the same effect can be obtained regardless of the arrangement of the water-impervious sheet 20 in any vertical position. When the water-impervious sheet is double, the second electrode is disposed in the middle layer of the double water-impervious sheet, and the second electrode is placed above the upper water-impervious sheet and below the lower water-impervious sheet, respectively. By arranging the first electrode, it is possible to inspect each of the upper and lower portions of the double impermeable sheet.

[0007]

In the above inspection method,
The resistance value of the damaged portion of the impermeable sheet depends on the size of the damage, and when the damage is small, the change in resistance is small. The current flowing between the upper and lower electrodes is determined by the applied voltage, the impedance between the upper and lower electrodes, and the resistance of the damaged portion of the impermeable sheet. For this reason, in order to detect small breakage, it is necessary to reduce the influence of the electrode impedance, and the laid electrode needs a large area.

[0008] However, if the electrode area is large, the plate-shaped electrode itself may cause damage to the impermeable sheet.
This is because, for example, when the ground vibrates due to an earthquake or the like, the water impermeable sheet is easily deformed together with the vibration of the ground, whereas the electrode having a large area is hardly deformed, and the water impermeable sheet may be damaged at the corner portion. Because. Also, if the electrode area is large, there is a problem in terms of construction and economy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a water-insulating sheet inspection system using electrodes which requires a small electrode area.

[0010] Another object of the present invention is to provide a water-blocking sheet inspection system using electrodes that are unlikely to cause damage to the water-blocking sheet.

[0011] The present invention further provides a waterproof sheet inspection system capable of detecting a damaged portion in a disposal site where electrical insulation is not ensured without being affected by leakage current flowing from a portion other than the damaged portion of the waterproof sheet. Is to provide.

[0012]

According to the present invention, a first electrode provided on one of the upper and lower sides of a water impermeable sheet, and a first electrode arranged on the other side of the water impermeable sheet are provided. A plurality of second electrodes, a power supply for applying a voltage between the first electrode and the second electrode, a current detection circuit, and a plurality of second electrodes arranged between the second electrode and the current detection circuit. An electrode switch that selects one electrode from the second electrode and connects to the current detection circuit and the other electrode connects to the power supply, and measures a current flowing through the second electrode. In the method for inspecting a water-impervious sheet, there is provided a method for inspecting a water-impervious sheet, wherein the second electrode is formed in a circular shape formed of a metal wire.

[0013] At least one metal wire may be connected to the inside of the circular second electrode so as to short-circuit two opposing points.

[0014]

In the inspection method according to the present invention, the current value measured for each of the second electrodes arranged on the other side of the impermeable sheet indicates that the electrode impedance increases as the area surrounded by the electrodes increases. Since the current easily flows down, an electrode having a large area is equivalently laid.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a waterproof sheet inspection system according to the present invention. FIG.
Sets the shape of the second electrode (corresponding to the second electrode 22 in FIG. 4) 10 that is two-dimensionally arranged below the impermeable sheet for use in the inspection method of the impermeable sheet according to the present invention. FIG. The present embodiment is characterized in that the shape of the second electrode 10 can be regarded as a state in which the electrode area is enlarged by making the shape of the second electrode 10 a circular shape made of a metal wire, here a ring shape. The second electrode 10 usually has a diameter of one to several (m) in diameter, and is connected to a connection line 11.

The configuration of the first electrode, power supply, electrode switch, and current detection circuit constituting the inspection system is the same as that shown in FIG. 4, but the scope of the present invention is shown in FIG. Not limited to the configuration, the present invention is applicable not only to the above-described double impermeable sheet but also to any other type of impermeable sheet inspection method based on the same principle.

FIG. 2 is a diagram showing a result of calculating a potential distribution when a current is applied to the second electrode 10 having a spiral shape according to the present invention. As with the conventional square or rectangular plate-like electrode, the potential on the outside of the second electrode 10 tends to decrease as the distance from the electrode periphery increases. However, since the inside of the second electrode 10 has a small decrease in potential and a high potential can be obtained, the same effect as the conventional plate-shaped electrode is obtained.

In addition, unlike the square or rectangular plate-shaped electrode, the second electrode 10 having a circular shape is easily deformed similarly to a water-impervious sheet, and has no corner portion. Therefore, even when the ground vibrates, there is very little possibility that the water-impervious sheet itself will be damaged.

FIG. 3 is a plan view showing another example of the second electrode used in the inspection system according to the present invention. Two wire electrodes 12 and 13 made of metal wires are connected to the inside of the second electrode 10 in a circular shape so as to short-circuit two points facing each other so as to be orthogonal to each other. As described above, by adding the line electrodes 12 and 13 to the second electrode 10 having the circular shape, the potential near the center of the second electrode 10 having the circular shape shown in FIG. It can be considered that the area is increased.

Although the embodiment of the present invention has been described above using the ring-shaped second electrode, the present invention is not limited to the ring-shaped second electrode. The effect of improving the problem of construction and economy due to the small electrode area can be obtained. Also,
In the present invention, the high-density polyethylene having excellent insulation properties is targeted as a material of the water-impervious sheet. However, the present invention can be applied to a water-impervious sheet showing carbon-based rubber-based conductivity. .

[0021]

As is apparent from the above description, according to the present invention, the first electrode is provided on one side of the impermeable sheet of the controlled type landfill, and a plurality of second electrodes having a circular shape are provided on the other side. Is used, and all the second electrodes other than the one second electrode selected by the electrode switch are connected to the ground side of the power supply, and the second electrode is technically and economically used. Since the shape and dimensions can be freely determined, the shape and arrangement suitable for the shape and electrical characteristics of the disposal site and the required inspection capability of the impermeable sheet breakage become possible. And since the breakage position of the impermeable sheet can be obtained by the two-dimensional coordinates, the position where the water leakage occurs can be accurately detected at an early stage, and the effect that the environmental destruction is minimized is obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing the shape of a second electrode used in a water-blocking sheet inspection system according to the present invention.

FIG. 2 is a characteristic diagram for explaining an effect of the second electrode shown in FIG.

FIG. 3 is a plan view showing a modification of the second electrode shown in FIG.

FIG. 4 is a configuration diagram for explaining a conventional waterproof sheet inspection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10, 22 2nd electrode 11 Connection line 12, 13 line electrode 20 Waterproof sheet 21 1st electrode 23 Power supply 24 Electrode switch 25 Current detection circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Fumio Sakata Inventor 4-22-11 Zenfukuji, Suginami-ku, Tokyo F-term (reference) 2D018 DA03 2G067 AA19 BB11 CC02 DD23

Claims (2)

[Claims] A first electrode provided on one of the upper and lower sides of the impermeable sheet; a plurality of second electrodes arranged on the other side of the impermeable sheet; A power supply for applying a voltage between one electrode and the second electrode; a current detection circuit; and one electrode from the plurality of second electrodes disposed between the second electrode and the current detection circuit. And the other electrode connected to the current detection circuit and an electrode switch connected to the power supply, wherein the current flowing to the second electrode is measured to inspect the impermeable sheet, A water-blocking sheet inspection method, wherein the second electrode has a circular shape formed of a metal wire. 2. The water-impervious sheet inspection system according to claim 1, wherein at least one metal wire is connected inside the orbiting second electrode so as to short-circuit two points facing each other. Insulation sheet inspection method characterized by the following.