JPH0915081A - Leakage detection system for impermeable structures at waste disposal sites - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention aims to prevent the waste disposal site, which is one of the essential social infrastructures, from causing pollution such as pollution of water resources and groundwater. A water leakage / water intrusion detection device applied to a water shielding structure constructed of a polymer material, which facilitates water leakage or water infiltration in the water shielding structure of a controlled disposal site for industrial waste / general waste, Along with the construction of a system that can be reliably and easily detected without special specialized knowledge, safety management and maintenance of these facilities can be performed at low cost, and for long-term operation. The main purpose is to establish a system that can withstand. [Composition] Three sets of electrodes and signal converters for the water-blocking structure at the waste disposal site, which is in the trend of requiring the use of double water-blocking sheets to ensure reliability for safety. By selecting the electrode combination in the water leak / water intrusion detector circuit that is composed of the combination of the above, accidents can occur in different applications, water leaks from the joints between the sheets and sheets that are double upper and lower sheets. And whether the occurrence of
It is possible to construct a system that can specify the location of occurrence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a system for easily and reliably electrically detecting inundation and leakage of water in a water-impervious structure, which can be used from a managed waste disposal site or a storage facility for hazardous materials. For the maintenance management of the impermeable structure provided to prevent the leakage of harmful substances or all water and industrial chemicals,

[0002]

2. Description of the Related Art As is well known, it is obligatory that a controlled final disposal site for landfill disposal of industrial waste and general waste has a water-impervious structure to prevent leakage of harmful substances from the facility. It is being done. The water-blocking structure is generally constructed of a water-blocking sheet made of a polymer material such as synthetic rubber or polyethylene. The structure is such that a plurality of unit water-impervious sheets are joined by means such as adhesive or heat fusion to secure the required area, and are laid on the ground or inside a building constructed of concrete, etc. Build a water structure.

The purpose of water shielding is to contaminate rainwater that has permeated waste that is considered to contain harmful substances, or to permeate groundwater that has leached onto the ground, and prevent its reverse flow to contaminate groundwater. There are cases where a single impermeable sheet is used as the impermeable structure and one is constructed with double impermeable sheets in order to prevent such problems.

When a double waterproof sheet is adopted, it is attempted to establish a monitoring system for detecting water leakage or water infiltration due to a defect of the waterproof sheet, and also to secure the physical strength of the structure. It is a thing.

In order to prevent the diffusion of harmful substances when a defect occurs in the impermeable sheet, the position where the defect occurs (water leak point) is specified and the defect is repaired. Is the only means. And in order to proceed with the repair work,
First of all, the position must be specified. Detection principles based on electrophysics and detection methods based on other principles are conceivable for identifying the leak point.

[0006] Further, from the advantage that the physical strength can be ensured by making the water-impermeable sheet double, the use of double water-impermeable sheet will be the mainstream in the future. And one of the structures is to provide an independent small section by partitioning the space created between the double water-blocking sheets, enclose the detector electrode in this small section, and to connect the signal line from the electrode. To the management building and connect it to an appropriate signal converter to build a leak monitoring circuit based on electrophysics.

When detecting means based on other principles is applied, a conduit is connected to each of the above-mentioned small sections, which is led to a management building and sucked by a vacuum pump or the like to leak air or water. There is a method of inspecting the presence or absence of water and detecting the presence or absence of a defect in the water shield sheet.

Usually, the above small sections are secured by superimposing two water-impermeable sheets having a certain area and closely bonding the peripheral edges thereof. Then, these are generally used as a water-impervious unit, and a plurality of the water-impervious units are generally heat-sealed or bonded with an adhesive to secure a necessary area to form a water-impervious structure. Therefore, in order to detect defects in the joint surface between the above-mentioned water-impervious units, that is, to detect water leakage from this part, what kind of detection principle is used unless another detector is provided for that purpose? Even if you use
It cannot be detected.

In the case of being based on electrophysics, the detection principle can be roughly classified into two methods, that is, the fluctuation of the electric resistance or the conductivity which is the reciprocal of the electric resistance. The detection signal when the electric resistance is used as an index is a voltage signal, and when the conductivity is used, it is a current signal.

In a water-blocking structure composed of two layers of a water-blocking sheet having a large area formed by joining a plurality of single water-blocking sheets, one of a pair of electrodes constituting a detector is moved. A movable electrode structure is possible, and the other electrode is arranged in a mesh between the two water shield sheets, and if there is a change in the resistance between the electrodes, it is considered that a water leakage accident has occurred. There is a way. Then, there is a method in which a known current is made to flow between both electrodes in order to identify and detect the water leak point, and the movable electrode is sequentially moved to monitor the variation in the electric resistance between the electrodes to form a water leak point detection circuit. In this case, it is useful for monitoring the water blocking sheet interposed between both electrodes, but is not useful for monitoring the other sheet.

When the presence or absence of water leakage is intended to be detected by the principle of electrophysics, and when it is applied to a water-impervious structure constructed by a single water-impervious sheet, a water-impervious structure is used between a pair of electrodes. The electrodes are arranged in an electrically insulated form to form a detection circuit. Then, in order to identify the water leakage position, one electrode of the pair of electrodes electrically insulated by the water-blocking sheet is used as a movable electrode, and the electrodes are sequentially moved so that electrical resistance or conductivity is obtained at a plurality of points. Measure the rate. When using each of these as an index, the resistance or conductivity between the leak point and the measurement point is measured from the theorem that each is proportional to the specific resistance of the measurement object and the distance between the electrodes, and the water leakage is calculated from the deviation of the measured values. Detect points
It is devised to identify.

In a water-impermeable structure constructed of double water-impermeable sheets, a pair of electrodes having an area between two electrodes are electrically insulated from each other by an electric insulator. As a form of sandwiching, the periphery of the sheet is sealed with an adhesive or a means such as heat-sealing, and this is used as a unit water-impervious unit, and a plurality of such unit water-impervious units are adhesively or heat-sealed. For the water-impervious structure that is constructed by vertically and horizontally joining with other means to secure the required area, guide each electrode of each unit impermeable unit to the signal converter, and use the resistance value or conductivity as an index. It is possible to construct a water leakage detection circuit. In any of the above cases, since the unit impermeable unit is the management unit, the presence or absence of water leakage and the water leakage point for each unit can be grasped at the same time. However, it is not possible to determine which of the two sheets that make up the unit impermeable sheet has a defect, and it is not possible to detect water leakage at the joint between the joined unit impermeable units. There is.

[0013]

[Problems to be Solved by the Invention] The proposition of providing a water-impervious structure is to prevent the diffusion of harmful substances, and the cause of a water leakage accident is the loss of the intended function of the water-impervious structure. . And the necessity of the water leakage detection system and its installation purpose are to detect the occurrence of the water leakage accident, to reliably identify the position of the water leakage point, and to eliminate and repair the cause easily and at low cost. And establishment of a water leakage detection system that enables monitoring of water leakage accidents over a long period beyond the service life of the facility.

In a water-impervious structure constituted by two layers of water-impervious sheets having a large area formed by joining a plurality of single unit water-impervious sheets, a water leakage accident occurs in the water-impervious structure. There are three possible causes of (1) the case where both sheets are damaged, and the case where either one of the side contacting the waste or the side contacting the ground is damaged. In this case, it becomes important to judge which seat the accident occurred.

In a water-impermeable structure constructed of double-layered water-impermeable sheets, an electrode is sandwiched between two water-impermeable sheets having a certain area, and the periphery of the sheet is bonded with an adhesive or It is sealed by means of heat fusion or the like, and this is used as a unit impermeable unit. Then, a plurality of these unit water-impervious units are bonded with an adhesive or by means such as heat fusion to secure the required area, and the unit water-impervious structure is constructed. Leakage accidents from the joints between units cannot be detected by the above-mentioned conventional technology.

When water leakage is detected by the fluctuation or deviation of the electric resistance value, generally, the resistance is measured by applying a known current to the object to be measured and measuring the voltage drop at that time.
It is derived from Ohm's law. The information at this time is a voltage signal, and at a waste disposal site or the like, it is necessary to extend the signal line of at least 200 m or more in order to guide the signal to the management building or the like. Redundant signal lines when handling a voltage signal are easily affected by disturbances such as electromagnetic induction, so that the signal level must be sufficiently large compared to the noise component so that the effect can be ignored. Then, unless the influence of disturbance is reduced, there remains a problem in the reproducibility of measurement, so reliable data cannot be obtained without specialized knowledge.

The electric conduction in the aqueous solution is carried out by the movement of ions, and it behaves differently from the electron conduction.
As one of them, if the electric conductivity (= high resistance value) is low, it is difficult to increase the current density, so to obtain the required signal level, either increase the voltage between the electrodes or decrease the resistance value. That is, the distance between the electrodes must be shortened.

The resistance measurement in the system can be regarded as the same as the electrolysis work of the aqueous solution. Therefore, the greater the energy consumed between the target electrodes, the greater the electrochemical work between the electrodes, and the behavior of the ions in the aqueous solution is that the ion distribution between the electrodes is linear. As a result, it becomes unreliable and leaves a problem in reproducibility of the measurement result.

[0019]

[Purpose of the Invention] A waste disposal site, which is one of the necessary social infrastructures and is an indispensable facility, should not cause pollution, pollution of water resources, groundwater, etc. In Japan, waste disposal facilities are often installed upstream, so it is necessary to completely prevent leakage of contaminated water and harmful substances from the facilities. For that purpose, there is the establishment of reliable facility management technology by solving the problems of the conventional technology, and reliable results can be obtained without the knowledge of a professional engineer for its operation. The establishment of a system that can withstand the operation of.

[0020]

[Means for Solving the Problems] In order to carry out the above-mentioned purpose, the water leakage detection system has three or four electrodes A, B,
It is composed of C and D and an appropriate signal converter. The unit detector is composed of a pair of electrodes, and among the three or four electrodes provided, the combination is selected by the changeover switch provided in the signal converter to realize a plurality of different target functions. Allow the built-in water leakage detection circuit to be configured. And the electrode material is a combination of different materials,
If it is necessary to process the signal that can be extracted as a current value and the other as a voltage value, the physical distance between the relevant detector electrodes that can extract a high signal level can be set short, and the function may be lost in long-term use. The voltage signal is adopted only when there is no.

[0021]

Function A plurality of leak detection circuits for different detection purposes can be constructed with a minimum number of electrodes. Moreover, by making the electrodes that make up the detector different materials, the detection signal can be made to have a current value. In that case, the electrodes are usually non-potential (no voltage) with respect to the ground, so they are especially movable. Safe handling of electrodes. By making the signal a current value, the influence of electromagnetic induction etc. is reduced and the restriction on the extension of the signal line is reduced.
Also, no special measures such as electromagnetic shielding for the signal line are required. When the conductivity is used as an index, the detector is a self-power generation type detector. Therefore, when it is necessary to construct a plurality of detection circuits, the influence between the detection circuits is reduced and the reproducibility of the measurement result can be secured. Therefore, reliable measurement results can be obtained even without specialized knowledge.

[0022]

EXAMPLES Hereinafter, as a structure of the water-impervious structure according to the present invention, there are a case of using a single water-impervious sheet in two layers and a case of constructing the water-impervious unit unit shown in FIGS. An embodiment of a leak detection system based on electrophysics applied to each will be described in detail with reference to the accompanying drawings.

FIG. 5 shows electrodes A (16), B (13a) for constructing a water leak detector in the case of a water blocking structure constructed by joining a plurality of the water blocking unit units shown in FIG. C (1
4a) and D (17). Each of the electrodes can be made of the same kind or different kinds of materials, and the signal output of the detector when the combination of electrodes of the same kind of material is a voltage value (= resistance value), When the combination of different materials is used, the signal output is the current value (= conductivity). The water leakage detection system is composed of a signal converter capable of sequential or simultaneous parallel monitoring for each water-shielding unit and a detector composed of a combination of electrodes. In this case, the electrode A is a movable electrode, and the electrode D (17) is laid on the ground in a mesh shape.
The detector configuration can be a combination of A-B, B-C, C-D and A-D. The detector composed of the electrodes A-D is used for detecting water leakage from the joint between the water-impervious unit units (10a), and the movable electrode A is moved to sequentially measure the current value (conductivity). This will identify the leak point.
As an actual monitoring method, while constantly monitoring the detector composed of the combination of electrodes B-C and A-D, when an abnormality occurs, the detectors A-B and C-D are selected to It is determined which of 11 and 12 has an accident. When all electrodes are made of different materials, it is a good idea to select the ionization tendency of the materials in the order of electrodes A>B>C> D. The reason for this is that in signal processing, processing a current signal has more advantages than processing a voltage signal. Electrodes B and C are protected by the water shield sheet as long as there are no defects in the water shield sheet, so there is no risk of corrosion, and there is a risk of electrochemical corrosion when exposed to groundwater leached on the ground. D (17) can be dealt with by using a carbon or graphite-based material which is the most common and does not cause corrosion. Further, since the electrode A (16) is a movable electrode, it can be maintained in consideration of corrosion and the like, so that there is an advantage that the range of material selection is widened. When the electrodes are made of the same material, the electrodes B (13a), C (14a), and D ( 1
Even if 7) is made of the same material and the measurement principle of resistance variation is applied, the problem of reproducibility of measurement results is somewhat improved, but there is no particular advantage. The electrodes B (13a) and C (14a) are made of a woven cloth such as polyethylene and subjected to electroless plating when different materials are selected in order to ensure the ability to follow the ground.
A carbon fiber woven cloth or a carbon pile is optimal for the electrode D. When the same kind of material is selected for the electrodes B and C, carbon fiber woven cloth is selected for the electrodes B (13a), C (14a) and D (17). FIG. 7 shows an example of an equal load circuit and a measurement circuit when all the detectors are in operation when each electrode is made of a combination of different materials.

FIG. 6 is a sectional view of a water-blocking structure constructed by vertically and horizontally compounding a plurality of the water-blocking unit units shown in FIG. Three electrodes A (16), B (23a), C for
It is a schematic diagram which shows arrangement | positioning of (27). In this case, electrode A
Is a movable electrode, and the electrode C is laid in a mesh on the ground,
Each of the electrodes A and B is connected to the signal converter so that each of the plurality of electrodes B serves as a common electrode, and a plurality of detection circuits are configured in combination with the electrodes of each unit sheet. In this case, the materials used for the electrodes are different from each other, and the ionization tendency of the materials is A>B> C, whereby it is possible to configure detection circuits for different purposes using the current value as a signal. The advantages and disadvantages are the same as above. The structure and operation of the water leakage detection system are such that each water-impervious unit is used as a management unit for electrode B
-C and the detector which is a combination of electrodes AB are used for sequential or parallel monitoring. By constantly monitoring the detectors composed of the electrodes A to C, accidents of the respective water shield sheets (21a and 22a) constituting the unit water shield sheet and the joint portion between the unit water shield sheets are detected. Water leakage can be detected. Then, when the operation of the detector which is the combination of the electrodes of the detectors A-C is confirmed, the electrode A is moved to sequentially measure the current value (= conductivity), and the deviation from the junction site is measured. The leak point can be specified.

FIG. 8 shows a structure for forming a water leak detector in a water-impervious structure having two layers of water-impervious sheets having a large area formed by joining a plurality of single water-impervious sheets. Three
It is a figure which shows arrangement | positioning of individual electrode A (16), B (33), C (34). The electrode B is laid between the layers of the water-blocking sheet, and the electrode C is laid on the ground in a mesh pattern, and the electrode A is arranged as a movable electrode structure. In this case, by selecting the signal line (electrode), a detector having a combination of AB, AC, and BC can be configured. As a monitoring system, if a breakage occurs in the water-blocking sheet 31, a detection circuit composed of the electrodes AB operates, and if there is an accident in the water-blocking sheet 32, a detection circuit composed of the electrodes BC operates to cause a water leakage accident. Will be notified. Then, the water leak point of the water shield sheet 31 is specified by moving the electrode A (16) to sequentially measure the resistance value or the conductivity, and the deviation point is used to specify the water leak point. In this case, there is a drawback that the water leakage point generated on the sheet 32 cannot be specified.

[0026]

EFFECTS OF THE INVENTION A leak detection circuit for a plurality of detection purposes can be constructed with a minimum number of electrodes. Then, a highly reliable detection system can be constructed without the need for continuous monitoring in time and without any specialized knowledge of electricity and the like. By establishing a system that can withstand long-term operation, it is expected that the anxiety of residents around the facility will be resolved and the operation and management of the facility will be open without concealing the presence or absence of a water leak accident.

[Brief description of the drawings]

[Figure 1] Front view of water-impervious structure

FIG. 2 is a sectional view taken along line X-X ′ of the water-impervious structure.

[Fig. 3] Impermeable unit unit (I) that constitutes the impermeable structure
Cross section of

FIG. 4 is a water-blocking unit unit (I
Cross section of I)

FIG. 5 is a sectional view of an electrode arrangement of a water-impervious structure composed of the water-impervious unit (I).

FIG. 6 is a sectional view of an electrode arrangement of a water-impervious structure composed of the water-impervious unit (II).

FIG. 7 is an equal-load circuit during operation of a detector having a combination of different materials with the electrode arrangement shown in FIG.

FIG. 8 shows a water-impervious structure composed of two water-impermeable sheets having a large area formed by joining a plurality of single water-impermeable sheets, and is composed of three electrodes A, B, and C. The electrode arrangement sectional drawing in the case of a water leak detection system.

[Explanation of symbols]

10a Water-impervious unit constituting water-impervious structure 11, 12 Sheet of synthetic rubber or the like 13 Electrode B 14 Electrode C 15 Insulator 21, 22 Sheet of synthetic rubber 23 Electrode B 25 Cushion material having water absorption, insulator 13a Electrode B 14a Electrode C 15a Insulator 16 Movable Electrode A 17 Electrode D 18 laid in a mesh on the ground Waste 18a, 22a Synthetic rubber sheet 23a Electrode B 25a Water-absorbent cushioning material 27 Ground Electrodes D 31 and 32 laid in a mesh shape on the water-permeable sheet 33 composed of a plurality of water-impervious sheets joined together, and electrodes B 34 laid in a mesh shape between the water-impermeable sheets Electrode C K-1, 2, 3, 4 laid on the substrate is an equal load circuit during operation of a detector composed of electrodes of different materials M Current / voltage signal converter

Claims (6)

[Claims] 1. A water leak detection system comprising three electrodes A, B and C in a water shield structure constructed of doubled water shield sheets. The structure is such that the planar electrode B is sandwiched between two water-impervious sheets having a certain area, and the periphery of the water-impermeable sheet is sealed by means such as an adhesive or heat fusion. It will be a unit impermeable unit. Then, an electrode is attached to a water-impervious structure constructed by securing a required area by vertically and horizontally joining a plurality of these unit water-impervious units with an adhesive or means such as heat fusion. C is laid on the ground where the water-impervious structure is constructed, a plurality of movable electrodes A are separately prepared, and a signal line from each electrode is connected to an appropriate signal converter to form a water leakage detection circuit. . And by selecting the combination of electrodes, it is possible to select the application function that suits the purpose of detection. The covering of the electrode B with a cushion material or a non-woven fabric or paper as a water-conducting material is not restricted, and the electrode B may not be a planar electrode. 2. A water-impervious structure comprising two layers of a water-impermeable sheet having a large area formed by joining a plurality of single unit water-impervious sheets, and three electrodes A, B, C. Leakage detection system consisting of. The electrode A has a movable electrode structure, and the electrode B is arranged in a mesh pattern between the layers formed by the water-impermeable sheet,
The electrodes C are arranged in a mesh on the ground. Then, the signal line from each electrode is connected to an appropriate signal converter to form a water leak detection circuit. And by selecting the combination of electrodes, it is possible to select the application function that suits the purpose of detection. 3. A water leakage detection system comprising four electrodes A, B, C, D in a water-impervious structure constructed of double water-impervious sheets. The configuration is such that a pair of planar electrodes B and C, which are insulated from each other by an electric insulator, are sandwiched between two water-impervious sheets having a certain area, and a peripheral edge of the water-impermeable sheet is bonded with an adhesive or It is sealed by means such as heat fusion. This is used as a unit water-impervious unit, and a plurality of such unit water-impervious units are vertically and horizontally joined by an adhesive or by means of heat fusion or the like to secure a required area to construct a water-impervious unit. With respect to the structure, the electrodes D are laid in a mesh shape on the ground where the water-impervious structure is constructed, a plurality of movable electrodes A are separately prepared, and a signal line from each electrode is provided with an appropriate signal converter. And a leak detection circuit. By selecting the combination of the electrodes, a water leak detection system that enables you to select the application function that suits the detection purpose. Then, the electrodes B and C are made of non-woven fabric.
It is not limited to cover with a water-permeable material such as paper, and both electrodes do not have to be planar. 4. The electrode A, B, C or D of the system according to claim 1, 2 or 3 is composed of electrodes made of different materials. 5. The electrodes A, B, C or D of the system according to claims 1, 2 and 3 are composed of electrodes made of the same material. 6. An electrode in which a combination of electrodes made of different kinds and the same kind of materials coexist when selecting a combination of electrodes among the electrodes A, B, C or D of the system of claims 1, 2 and 3. The configuration.