JP2004045218A - Detector and method for detecting leakage of water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect leakage of water in a detection area by generating strain or bending in an optical fiber in the leakage of water, using a water leakage detecting sensor attached to the optical fiber. <P>SOLUTION: This detector/method for detecting the leakage of the water is provided with a water barrier face member 42 having a water barrier property such as a water barrier sheet and a water barrier layer, the optical fiber 1 arranged at least one face side of the water barrier face member 42, and the water leakage detecting sensor 2 attached to the optical fiber 1 to generate the strain or bending in the optical fiber 1 when detecting the water. When the sensor 2 detects the water, the strain or bending is generated in the optical fiber 1 to detect the water leakage in the water barrier face member 42. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water leakage detection device that detects water leakage including inundation, and a water leakage detection method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a device for detecting water leakage of a seepage control sheet used in a final waste disposal site or the like, a physical detection method and an electrical detection method are generally classified. Physical detection methods include sewage collection and drainage pipe method, compartment collection and drainage method, and vacuum suction method. Electrical detection methods include potential measurement method, potential / resistivity method, current measurement method, and impedance (AC resistance). There is a law. In addition, there is a method of detecting a water leak by measuring a temperature distribution using an optical fiber.
[0003]
In any of the physical detection methods, a groundwater collecting and draining system is used, and it is possible to detect a leak without largely changing the structure of a disposal site or the like. However, there is a drawback that it takes time to grasp the leak and that the leak position cannot be specified.
[0004]
The electrical detection method utilizes the insulation properties of the impermeable sheet, and measures the distribution of potential, current, etc. between the two electrodes sandwiching the impermeable sheet when the impermeable sheet is broken, and detects the leak location I do. This method cannot detect the impermeable sheet material unless it is insulative. In addition, since conductive electrodes are laid at the final waste disposal site, there is a drawback that they are susceptible to electrical influences such as lightning and induced current. In addition, it is necessary to measure the position of the electrode for detection at the time of installation. In addition, since one or more cables from electrodes are required for one electrode, the number of cables becomes large when the number of electrodes is large, and the space for collecting cables is very close to the measuring device. There is a disadvantage that it becomes larger.
[0005]
The temperature distribution measurement method using an optical fiber measures a temperature change due to water leak, and since the leak location is underground, the temperature hardly changes locally, making accurate detection difficult.
[0006]
[Problems to be solved by the invention]
<A> The present invention is to make it possible to easily detect water leakage in a water leakage detection area.
<B> Another object of the present invention is to make it possible to detect water leakage at an arbitrary position in the water leakage detection area.
<C> Another object of the present invention is to make the detection of water leakage hardly affected by the external environment.
[0007]
[Means for Solving the Problems]
The present invention relates to a water-blocking sheet having a water-blocking property such as a water-blocking sheet or a water-blocking layer, an optical fiber disposed on at least one surface side of the water-blocking sheet, and an optical fiber attached to the optical fiber and detecting water. A water leakage detection sensor that generates strain or bending in the fiber, and, when the water detection sensor detects water, generates distortion or bending in the optical fiber and detects water leakage of the impermeable surface body, In the leak detection device.
The present invention also resides in the above-described water leakage detection device, wherein a plurality of water-impervious surface members are stacked, and an optical fiber and a water leakage detection sensor are arranged therebetween.
The present invention also provides the water leakage detecting device, wherein the water-impervious sheet is a water-impervious sheet, the optical fibers meander between the superposed water-impervious sheets, are arranged in a lattice or a spiral, and There is provided a water leakage detection device, wherein water leakage detection sensors are arranged at a plurality of locations.
The present invention also resides in the water leakage detection device according to the above water leakage detection device, wherein the superposed water-impervious sheet is disposed in a region of the waste disposal site where water is to be impermeable.
The present invention also provides a water-impervious sheet having a water-imperviousness such as a water-impervious sheet or a water-impervious layer in a water leakage detection area, an optical fiber disposed on at least one surface side of the water-impervious sheet, and detecting water. Attach a water leak detection sensor that generates distortion or bending to the optical fiber, transmits light to the optical fiber, receives light returning from the optical fiber, measures distortion or bending loss of the optical fiber, and detects water leakage A method for detecting water leakage, comprising detecting water leakage in an area.
The present invention also provides a water leakage detection sheet in which an optical fiber arranged in a meandering or lattice shape and a water leakage detection sensor attached to the optical fiber are disposed between a superimposed sheet and a wastewater detection sheet. It is placed in the leak detection area of the disposal site, and when the leak detection sensor detects water, it generates distortion or bending in the optical fiber, transmits light to the optical fiber, receives light returning from the optical fiber, A method for detecting water leakage, comprising measuring strain or bending loss and detecting water leakage in a water leakage detection area.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0009]
<B> Leakage detection device Leakage detection device is a device that is installed in a water leakage detection area to detect water leaking. For example, a waste disposal site such as a managed disposal site or a final disposal site, a reservoir, a building, etc. It can be used in a leak detection area such as a roof that detects leaks.
[0010]
The water leakage detecting device includes a water impermeable sheet having a water impermeable property such as a water impermeable sheet or a water impermeable layer, an optical fiber disposed on at least one side of the water impermeable sheet, and a water leak detection sensor attached to the optical fiber. A strain and bending loss measuring device is attached to the end of the optical fiber to detect water leakage in the water leakage detection area. The term “water leakage” includes the concept of flooding, and means that water is generated for some reason.
[0011]
For example, taking the waste disposal site 4 as shown in FIG. 1 as an example of the water leakage detection region 41, the optical fiber 1 is laid on the bottom and side of the waste disposal site 4, and the water leakage detection device is arranged. At the bottom and sides of the waste disposal site 4, multiple water-impervious surface bodies 42 are disposed on the upper surface and the water-impervious surface body 42 on the lower surface to prevent water contained in the waste 43 from leaking. are doing. The optical fiber 1 is laid between the upper and lower water-impervious planar bodies 42, and the water leak detection sensor 2 is attached to the optical fiber 1. Since the water leakage detection sensor 2 is disposed between the upper and lower water-impervious surface members 42, if there is no water leakage location on each of the upper and lower water-impervious surface members 42, the water contained in the waste 43 is shut off, It can also block groundwater intrusion into the ground. A strain and bending loss measuring device 3 is attached to the end of the optical fiber 1.
[0012]
<B> Water Leak Detection Sensor The water leak detection sensor 2 generates distortion or bending in the optical fiber 1 when detecting water leak. The water leak detection sensor 2 is a sensor that generates strain or bending in the optical fiber 1 as shown in FIG. 2, for example, and passes through the optical fiber 1 in the container 21. The container 21 includes a recess 22, a cylinder 23, and a water passage 24. In the cylinder 23, a pressing member 25 having a convex portion 26 movable like a piston is arranged. In the cylinder 23, an expansion body 27 that expands in contact with water is arranged on the water passage 24 side. When water enters the cylinder 23 from the passage 24 and comes into contact with the expansion body 27, the expansion body 27 expands and presses the pressing member 25 against the concave portion 22 of the container. At this time, the optical fiber 1 is sandwiched between the concave portion 22 of the container 21 and the convex portion 26 of the pressing member 25, and distortion or bending occurs.
[0013]
<C> Water Leak Detection Sheet The water leak detection sheet 5 is formed by integrating a water leakage sheet 51, which is a water-permeable surface member 42, with the water leakage detection sensor 2, and a plurality of water leakage sheets 51, 51 are overlapped. An optical fiber 1 and a water leak detection sensor 2 attached to the optical fiber 1 are arranged on the optical fiber 1. As shown in FIG. 3, for example, the water leakage detection sheet 5 has a meandering optical fiber 1 disposed between a plurality of water shielding sheets 51, and water leakage detection sensors 2 are attached to a plurality of locations of the optical fiber 1. FIG. 3B is a cross-sectional view taken along line BB of the water leakage detection sheet 5 of FIG. In addition, when the water leakage detection sheet 5 detects water leakage uniformly over the entire surface, the optical fibers 1 may be arranged over the entire surface, and may be arranged in a lattice shape in addition to the meandering shape. There is also a method of arranging the optical fibers 1 in a spiral shape (circular, angular, etc.). Although the water leakage detection sheet may be created on site, it is manufactured in advance in a factory and laid on site to improve work efficiency. When a water-impervious sheet is used separately for water-imperviousness, the water-impervious sheet 51 of the water leakage detection sheet 5 has no water-imperviousness, allows water to pass through, and allows the optical fiber 1 to be fixed. It may be replaced. One of the water-blocking sheets 51 of the water leakage detection sheet 5 may be a water-permeable sheet, or an appropriate number may be a water-permeable sheet.
[0014]
<D> Strain or bending loss measuring device The strain or bending loss measuring device 3 measures the strain or bending loss generated in the optical fiber 1. The strain or bending loss measuring device 3 can detect the presence or absence of a strain or bending loss to detect the presence or absence of water leakage, and further, measure the strain or bending position of the optical fiber 1 and also detect the location of water leakage. be able to.
[0015]
The strain or bending loss measuring device 3 includes, for example, an optical switch 32, a strain or bending loss measuring device 31, and a measurement computer 33 in the case shown in FIG. When a plurality of optical fibers 1 are arranged, the optical switch 32 is a switch that switches between the plurality of optical fibers, and serves as a single strain or bending loss measuring device 31 for the plurality of optical fibers. is there. The strain or bending loss measuring device 31 measures the amount of strain or optical loss due to bending generated in the optical fiber 1 and its position. The measuring computer controls the strain or bending loss measuring device 31 and processes the measured data.
[0016]
The strain and bending loss measuring devices 31 include a strain measuring device for measuring a strain amount and a bending loss measuring device for measuring a bending loss. The strain measuring device detects the amount of distortion by measuring the light propagation loss caused by the strain generated in the optical fiber 1 and the frequency shift of the Brillouin scattered light (B-OTDR). The bending loss measuring device performs measurement using the backscattered light of the optical fiber 1 and the bending loss of the optical fiber 1. When a locally bent portion occurs in the optical fiber 1, leakage of transmitted light occurs and transmission loss of light in the fiber 1 increases. The loss occurrence position and the optical loss amount are detected by a strain and bending loss measuring device 31 connected to the optical fiber 1 as shown in FIG. 2 (OTDR method).
[0017]
Hereinafter, a method for detecting water leakage will be described with reference to the drawings.
[0018]
<A> Installation of a water leakage detection device A water leakage detection sheet 5 capable of blocking water is laid in a water leakage detection area 41 such as a waste disposal site 4. Alternatively, a lower water-impervious sheet body 42 such as a water-impervious sheet or a water-impervious layer is disposed in the water leakage detection area. The optical fiber 1 is disposed near the surface of the water-impervious planar body 42. The arrangement pattern of the optical fibers 1 is arranged at a position where water leakage is detected. For example, the arrangement pattern is arranged in a meandering, grid-like or spiral (circular, angular, etc.) manner. A water leakage detection sensor 2 is attached to an optical fiber 1 at a location where water leakage is detected. A strain or bending loss measuring device 3 is connected to the end of the optical fiber 1. The upper water-impervious body 42 is arranged so as to sandwich the optical fiber 1. Water is shielded so that water does not enter from the ends of the two water-impervious planar members 42, 42. In addition, in this example, two sheets of the water impermeable surface were used, but when there is water leakage from only one, the water impermeable surface 42 may be arranged on the side where the water leaks, and in that case, only one sheet may be used. In addition, in order to increase the water blocking strength, a plurality of sheets may be overlapped, or an optical fiber and a water leakage detection sensor are arranged between a plurality of the plurality of water blocking planes so that safety can be confirmed. Is also good.
[0019]
<B> Water Leak Detection When detecting water leak detection in the water leak detection area, first, a specific optical fiber 1 is selected by the optical switch 32. Light is sent from the strain or bending loss measuring device 31 to the selected optical fiber 1 into the optical fiber 1. The light propagates in the optical fiber 1 between the upper and lower water-impervious planes 42 in the water leakage detection area 4. The light partially reflects during the propagation and returns to the strain or bending loss measuring device 31. The strain or bending loss measuring device 31 measures a reflected wave. The measurement computer 33 processes the reflected wave received by the strain or bending loss measuring instrument 31 and displays data and a waveform. Note that the strain or bending loss measuring device 3 may have the function of the computer 33 for measurement.
[0020]
<C> Water leak detection measurement (OTDR method)
FIG. 4 shows a relationship between the optical loss amount due to the bending loss of the optical fiber 1 and the distance in the measurement by the OTDR method of the strain or bending loss measuring device 3. The end of the curve P1 at the position where the distance is the minimum indicates the start point of the optical fiber 1, and the ends of the curves P2 and Q2 where the distance is the maximum indicate the end point of the optical fiber 1. When there is no breakage in the water-blocking planar member 42, light transmission loss is small, and curves P1 and P2 without water leakage as shown in FIG. 4 are displayed. In FIG. 1, when the water impermeable surface member 42 is damaged and water infiltrates through the water impermeable surface member 42 to expand the expansion body 27 of the light detection sensor 2, the optical fiber 1 is bent by the concave portion 22 and the convex portion 26. As a result, bending loss occurs in the optical fiber 1. At that time, the strain or bending loss measuring device 3 displays curves P1, Q1, and Q2 as shown in FIG. The amount of light propagation loss is indicated by a curve Q1, which makes it possible to specify the presence or absence of water leakage and the position of water leakage.
[0021]
<D> Measurement of leak detection (B-OTDR method)
FIG. 5 shows the relationship between the strain of the optical fiber 1 and the distance in the measurement by the B-OTDR method of the strain or bending loss measuring device 3. In FIG. 1, when the water impermeable surface member 42 is damaged and water infiltrates through the water impermeable surface member 42 to expand the expansion body 27 of the light detection sensor 2, the optical fiber 1 is bent by the concave portion 22 and the convex portion 26. As a result, distortion occurs in the optical fiber 1. At that time, the strain or bending loss measuring device 3 displays the frequency shift and the amount of strain due to the shift as shown in FIG. Thereby, the presence or absence of water leakage and the position of water leakage can be specified.
[0022]
In the above description, the waste disposal site 4 is described as an example. However, the present invention can be applied to any location as long as the location is a leak detection area for detecting water.
[0023]
【The invention's effect】
According to the present invention, the following effects can be obtained.
<A> The present invention can easily detect water leakage in a water leakage detection area such as a waste disposal site.
<B> Further, according to the present invention, since the water leakage detection sensor can be arranged at an arbitrary position of the optical fiber, the water leakage can be detected at an arbitrary position and with high accuracy.
<C> The present invention is not affected by an external environment such as a lightning strike or an induced current.
<D> Further, the present invention can be installed even with a water impermeable sheet having high conductivity.
[Brief description of the drawings]
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a water leak detecting device taking a waste disposal site as an example of a water leak detecting area. FIG. 2 is an explanatory diagram of a water leak detecting device detecting a water leak with an optical detection sensor. FIG. 4 is an explanatory diagram of measurement data obtained by measuring bending loss. FIG. 5 is an explanatory diagram of measured data obtained by measuring strain.
DESCRIPTION OF SYMBOLS 1 ... Optical fiber 2 ... Water leak detection sensor 21 ... Container 22 ... Concave part 23 ... Cylinder 24 ... Water passage 25 ... Pressing member 26 ... Convex part 27 ... Inflatable body 3 ... Strain or bending loss measuring device 31Strain or bending loss measuring device 32 Optical switch 33Measurement computer 4Waste disposal site 41Water leakage detection area 42 Waste 5: Water leakage detection sheet 51: Water-shielding sheet

Claims (6)

A water-impervious sheet having water-impermeability, such as a water-impervious sheet or a water-impervious layer;
An optical fiber disposed on at least one side of the water-impervious planar body;
A water leak detection sensor attached to the optical fiber and generating distortion or bending in the optical fiber when detecting water,
A water leakage detection device characterized in that, when water is detected by a water leakage detection sensor, strain or bending is generated in an optical fiber to detect water leakage from a water-impervious planar body. The leak detection device according to claim 1,
A water leakage detection device, comprising a plurality of water-impervious planar bodies stacked on each other, and an optical fiber and a water leakage detection sensor disposed therebetween. The leak detection device according to claim 1,
The water impermeable sheet is used as a water impermeable sheet, the optical fibers meander between the superposed water impermeable sheets, are arranged in a lattice or a spiral shape, and a water leakage detection sensor is arranged at a plurality of locations of the optical fiber. , A water leak detection device. In the water leakage detection device according to claim 2 or 3,
A water leakage detection device, wherein the superimposed planar bodies are arranged in a region of a waste disposal site where water is to be impermeable. A water-impervious sheet, such as a water-impervious sheet or a water-impervious layer, is placed in the water leak detection area,
Arranging an optical fiber on at least one surface side of the impermeable surface,
Attach a water leak detection sensor that generates strain or bending to the optical fiber when detecting water,
A method for detecting water leakage, comprising transmitting light to an optical fiber, receiving light returning from the optical fiber, measuring distortion or bending loss of the optical fiber, and detecting water leakage in a water leakage detection area. A water leakage detection sheet in which an optical fiber arranged in a meandering or lattice shape and a water leakage detection sensor attached to the optical fiber are disposed between superimposed sheets, and a water leakage detection area of a waste disposal site Placed in
When the water leak detection sensor detects water, it generates strain or bending in the optical fiber,
A method for detecting water leakage, comprising transmitting light to an optical fiber, receiving light returning from the optical fiber, measuring distortion or bending loss of the optical fiber, and detecting water leakage in a water leakage detection area.

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