JP2018066699A - Water pipeline degradation monitoring method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a damage caused by rust or the like, of a buried water pipeline P by a novel technology.SOLUTION: A distribution measuring type optical fiber sensor 11 is attached on the inner peripheral surface of a buried water pipeline 2(1) and the sensor is coated with a pipe inside protection layer 13. In a state in which a balloon 17 is loaded inside the pipeline 2 through a branch pipe 16 and water is made to flow in the balloon to apply constant pressure, detection light (a) is projected into the optical fiber sensor and reflection light (b) thereof makes it possible to detect strain at a portion of the water pipeline on which the optical fiber sensor is attached. At this time, if a recess 3 derived from thickness loss due to rust on the outer surface of the pipeline is generated with age, the pipeline becomes thinner and stress by pressure is concentrated, thereby making strain large. Since constant pressure is applied, size and a position of strain can be accurately measured without an influence of change in water pressure of water supply which usually occurs. With this, the pipeline deterioration state can be directly monitored, so that deterioration at a portion of the pipeline P where a monitoring pipeline is buried can be seen and a pipeline near the portion is replaced.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a deterioration monitoring method for water pipes and an apparatus therefor.

In order to systematically update an enormous length of aged water pipelines, it is necessary to set the priority of the update and level the renewal business. There is no official knowledge of the renewal base years required.
For this reason, in general, a predictive plan is that the water utility sets its own renewal reference years based on attribute data such as the laying year, pipe type and buried environment, and experience data such as the number of accidents such as water leakage. The method is used.
However, when performing pipeline renewal based on the above predictive technique, there is a concern about economic loss due to the occurrence of a sudden water leakage accident or renewal of the pipeline before reaching the appropriate life depending on the accuracy of the prediction.

  On the other hand, as technologies for monitoring the deterioration state of pipelines, technology for detecting leakage noise and vibrations in pipelines and technology for leakage monitoring by constantly monitoring the amount of water using smart meters are being developed. Since it is a technology for monitoring the presence or absence, it can be used to improve the accuracy of predictive methods based on data accumulation, but the above-mentioned economic loss cannot be eliminated.

  Under such circumstances, there is a technique in which a strain gauge is fixed to the pipe for the breakage or damage of the buried water pipe, and the deformation of the pipe is measured by a change in electric resistance of the strain gauge (Patent Document 1, Claim 1). , See FIG.

JP-A-9-243310 JP-A-11-344390

  In performing preventive maintenance against leakage accidents due to deterioration of aging pipeline facilities, it is not possible to eliminate sudden leakage accidents and the like only by time-planned maintenance that relies on prediction methods. In order to realize highly reliable preventive maintenance, it is necessary to introduce not only time-planned maintenance but also state monitoring maintenance that directly monitors the deterioration state of pipeline facilities. In particular, in iron-based water pipes, the strength of the pipe body decreases due to the occurrence of rust due to deterioration over time, and eventually the pipe body is damaged, leading to a water leakage accident. In other words, if a change in tube strength can be monitored, a water leakage accident can be prevented.

From such a point, the measurement by the strain gauge can be considered. However, since the measurement uses electricity, the water pipe requires an insulation treatment for water, and the treatment is complicated.
On the other hand, there is a technique for measuring damage of a pipe with an optical fiber sensor fixed to the pipe (see Patent Document 2, Abstract, FIG. 1, etc.).

  This invention makes it a subject to measure the damage by the rust etc. of the buried water pipe line by the novel technique under the above actual condition.

In order to achieve the above object, the present invention applies the measurement technique of the optical fiber sensor to the distortion measurement technique of the buried water pipe.
By adopting this configuration, it is possible to introduce state monitoring and maintenance, and it is possible to improve the economic loss that is a concern in maintenance management only by time-planned maintenance. That is, it is possible to eliminate the loss related to the restoration material and the restoration work accompanying the occurrence of a sudden water leakage accident from an unexpected location, and the economic loss due to the pipeline renewal before reaching the appropriate life.

In addition, the following effects (A) to (C) can be obtained by using a distribution measurement type optical fiber sensor as the tube state monitoring sensor.
(B) A general strain gauge can only measure points. Therefore, in order to monitor the entire state of the tube (tube body) without omission, a huge number of strain gauges are required, and there is a problem that the wiring (gauge lead wires) is very complicated. However, the distributed measurement type optical fiber sensor can measure strain at a plurality of points with a single optical fiber sensor, and can measure the strain of the tube surface according to the method of applying the optical fiber sensor. As a result, it becomes possible to monitor changes in the tube strain due to rusting where the occurrence location is unspecified, and no complicated wiring work is required.
(B) Since the water pipe is generally buried under the road and is in an environment where excavation and maintenance cannot be easily performed, it is desirable that the sensor installed in the pipe has a long life. In the present invention, it is possible to manage a buried object such as a water pipe by applying an optical fiber sensor having a very long life compared to a general strain gauge.
(C) Even if a part of the tube sticking part peels off, the optical fiber sensor can measure strain in the part where the sticking state is maintained unless it is disconnected, so the risk of strain measurement becoming completely impossible It is possible to monitor a water pipe with a very small and long service life over a long period of time.

  As a specific configuration of the deterioration monitoring device for water pipes according to the present invention, a distributed measurement type optical fiber sensor attached along the inner peripheral surface, outer peripheral surface or inner / outer peripheral surface of the buried water pipe, and the optical fiber thereof The sensor comprises a measuring device for injecting detection light, and detecting the distortion of the water pipe portion where the optical fiber sensor is attached by the reflected light. A configuration for measuring the degree of deterioration can be employed.

  In this configuration, the optical fiber sensor may be configured to be attached to the inner peripheral surface of the buried water pipe and covered with a pipe inner surface protective layer. Usually, water pipes, especially water supply pipes, are provided with a protective layer such as mortar lining or epoxy resin powder coating on the inner peripheral surface, so if the optical fiber sensor is covered with the protective layer, without increasing the work process, The durability of the optical fiber sensor can be improved.

This degradation monitoring device can be installed in the pipe when newly installed or can be installed in the existing pipe. However, a separate monitoring pipe is provided for the buried water pipe, and the optical fiber sensor is installed in the monitoring pipe. Or the optical fiber sensor can be attached and covered with a tube inner surface protective layer. The monitoring pipe can be inserted in the existing water pipe as well as in the new water pipe.
As described above, if a monitoring tube with an optical fiber sensor is separately provided, the monitoring tube can be mass-produced in a factory or the like, which can be advantageous in terms of quality and cost.

The optical fiber sensor may be attached in any manner as long as damage to the tube can be measured. For example, an embodiment in which the optical fiber sensor is attached in a wave shape or a spiral shape on the entire circumference of the tube can be employed.
In addition, the measurement by the optical fiber sensor can be performed continuously or intermittently, but if the water pipe part to be measured is pressurized, the distortion of the part appears remarkably, Measurement accuracy is improved because measurement can be performed under a certain pressure by a pressurizer without being affected by a change in the water pressure of a normal water supply. The pressurization measurement can be performed at regular intervals.
As the pressurizer, it is possible to employ one that performs the above pressurization by loading a balloon from the branch pipe into the buried water pipe or the monitoring pipe and flowing a fluid into the balloon.
Further, as a means for taking out the measurement signal from the optical fiber sensor, for example, a take-out pipe communicating with the buried water pipe or the monitoring pipe is provided, and the end of the optical fiber sensor is led out of the pipe from the pipe. At the lead-out end, the measuring device can be used to input detection light and measure the reflected light.

  As a specific configuration of the water pipe deterioration monitoring method according to the present invention, a distribution measurement type optical fiber sensor is attached to the buried water pipe along the inner peripheral surface, outer peripheral surface or inner and outer peripheral surface, and the optical fiber sensor is provided. It is possible to adopt a configuration in which detection light is injected into the water pipe, the distortion of the water pipe portion where the optical fiber sensor is attached is detected by the reflected light, and the degree of deterioration of the water pipe portion is measured based on the detected value. it can.

In this configuration, similarly, means for attaching the optical fiber sensor to the inner peripheral surface of the buried water pipe and covering with the pipe inner surface protective layer is adopted, or a monitoring pipe is interposed in the buried water pipe. The means for attaching the optical fiber sensor to the monitoring pipe may be adopted, or the means for attaching the optical fiber sensor and covering the pipe with an inner surface protective layer may be adopted.
Further, means for attaching the optical fiber sensor to the entire surface of the buried water pipe or monitoring pipe in a wave shape or a spiral shape, or means for pressurizing the water pipe portion to be measured can be adopted.
For the pressurization, a means for loading a balloon into the tube and allowing a fluid to flow into the balloon can be employed.
In addition, the buried water pipe or the monitoring pipe is provided with a take-out pipe communicating with the inside thereof, and the end of the optical fiber sensor is led out of the pipe from the pipe, and the detection light is input at the lead-out end, and A means for measuring the reflected light can be employed.
Of course, each means such as attaching the optical fiber sensor to the inner peripheral surface of the water pipe can be selectively employed as appropriate.

  Since the present invention is configured as described above, it is possible to detect a change in strain of the pipe body due to thinning due to the occurrence of rust in a water pipe such as an iron system, and monitor the deterioration state of the pipe. Make it possible.

Schematic of one embodiment of a method for monitoring deterioration of a water pipe line and its apparatus according to the present invention The principal part of the embodiment is shown, (a) is a schematic perspective view, (b) is a principal part cutaway view of (a). Main part sectional drawing of the same embodiment Sectional drawing of the principal part of the connector part of the embodiment Attached aspect explanatory drawing of the optical fiber sensor of the same embodiment Schematic cross-sectional view for explaining how the optical fiber sensor of the same embodiment is led out of the tube Strain state diagram due to rust etc. of pipe (water pipe) in the same embodiment Explanatory drawing of strain detection action of a water pipe part by the optical fiber sensor of the same embodiment Schematic diagram of another embodiment

  One embodiment of a deterioration monitoring apparatus for water pipes according to the present invention is shown in FIGS. 1 to 6, and this embodiment relates to a water supply pipe P. FIG. This pipe P is formed in a required length by sequentially inserting and fitting the insertion opening 1b of the other pipe 1 into the receiving opening 1a of one pipe (pipe body) 1. Similarly, a monitoring tube 2 is interposed in a part of the terminal 2 via the receiving port 2a and the insertion port 2b. The monitoring pipe 2 is provided with a deterioration monitoring device 10 according to the present invention.

  The degradation monitoring apparatus 10 introduces a distribution measurement type optical fiber sensor 11 and a detection light a into the optical fiber sensor 11 and detects distortion of a water pipe portion where the optical fiber sensor 11 is attached by the reflected light b. The measuring instrument 12

  The commercially available optical fiber sensor 11 has minute density unevenness in the glass molecules as its constituent elements, and this unevenness is different for each optical fiber sensor. In addition, the wavelength of light that is strongly Rayleigh scattered differs due to the difference in the refractive index of light due to density unevenness. The unevenness at each position of the optical fiber sensor 11 is called unique fingerprint information, and reflected light having the same wavelength is always generated unless the state of the optical fiber sensor 11 is changed. For this reason, when distortion occurs at a certain position of the optical fiber sensor 11, the wavelength of the reflected light is shifted by that position. By comparing the reflected light before the distortion and the reflected light after the distortion, it is possible to detect which position is distorted and how much.

  Various commercially available products can be used as the measuring device 12, but a strain / temperature distribution measurement type optical fiber sensor sensing dedicated device is adopted, and the minute reflected light “Rayleigh scattered light” in the optical fiber sensor 11 is converted into OFDR ( Measurements are made with milli-level position resolution by detecting with the Optical Frequency Domain Reflectometory method.

  Here, Rayleigh scattered light means reflected light called Rayleigh scattered light in the optical fiber sensor 11, and normally, scattering means that light is scattered in all directions when it hits particles (such as air molecules). Scattering is the scattering of light by a substance as small as 1/10 of the wavelength of light. For example, the sky looks blue because the sunlight is Rayleigh scattered by atmospheric particles, and the optical fiber sensor 11 similarly generates Rayleigh scattered light by glass molecules.

That is, as shown in FIG. 8, light (1510 to 1570 nm) whose wavelength is periodically changed enters the optical path from the wavelength tunable laser light source 12a, and is directed toward the optical fiber sensor 11 for sensing by the spectroscope 12c. (Measurement light) a is split into light and light (reference light) c that goes directly to the detector 12b.
Next, scattered light is generated over the entire optical fiber sensor 11 by the measurement light (detection light) a and becomes reflected light b. The reflected light b travels through the spectroscope 12c to the detector 12b, where the spectroscope 12c merges the measurement light a and the reflected light b, and the detector 12b obtains a change in light intensity due to interference.
The measurement data is subjected to Fourier transform, the scattered light frequency at each position of the optical fiber sensor is obtained, and the deviation (Δν) is obtained by comparing the unique frequency in the unique fingerprint information measured in advance with the frequency obtained by the measurement. Since the change amount of Δν is linearly determined by the material of the optical fiber sensor 11 and the wavelength of incident light, the strain amount is calculated from Δν. The position of the distortion (the position where the reflected light b is reflected) is the reflected light b that reaches the detector 12b and the reference that reaches the detector 12b directly in the light incident from the light source 12a (measurement light a and reference light c). Calculation is based on the time difference of light c.

The optical fiber sensor 11 may be attached (pasted) over almost the entire length of the inner surface of the monitoring tube 2 in the axial direction, but in this embodiment, it is attached to most of the straight part.
As an additional mode of the optical fiber sensor 11, the distribution measurement type optical fiber sensor 11 is generally arranged in a single stroke. Therefore, considering that the entire tube 2 is measured, FIG. Although the spiral sticking pattern as shown to (a) can be considered, the wave shape etc. which are shown in FIG. 5 are also considered. In the case of the corrugated shape, as shown in FIG. 5A, an optical fiber sensor 11 having a corrugated arrangement on one sheet 11a is prepared in advance, and the sheet 11a is pasted so as to be wound around the tubular body 1. Thus, it becomes possible to effectively measure the strain in the circumferential direction of the tube body 1 (see FIG. 5B).

As shown in FIG. 3, the optical fiber sensor 11 attached to the inner surface of the tube body 1 is protected by providing a protective layer 13 by mortar lining, epoxy resin powder coating, or the like, which is a general tube inner surface coating.
When the epoxy resin powder coating is applied to the inner surface of the tube 1, the tube 1 needs to be heated (160 to 230 ° C.). Since the optical fiber sensor 11 needs to be attached (attached) before heating the tube, a high-temperature type adhesive is used for bonding the optical fiber sensor 11. Moreover, since it sticks on the inner surface of a pipe | tube, the adhesive material which does not have a problem on water sanitation is desirable.

  In addition, a connector 14 for connection to the measuring instrument 12 is installed in advance at one end of the optical fiber sensor 11, but it is necessary to protect the connector 14 from being affected by heating when the tube body 2 is heated. There is. As the protection, a method using a heat insulating material 14a and a heat-resistant tape 14b can be considered as shown in FIG. The optical fiber sensor 11 can be used for temperature measurement up to a range of about 300 ° C., for example, if a polyimide-coated material is employed.

As shown in FIGS. 2 and 6, a water faucet 15 with a saddle 15b is attached to a position corresponding to one end of the optical fiber sensor 11 of the monitoring tube 2. That is, the optical fiber sensor 11 is passed through the small-diameter pipe 15 joined to the water faucet with the saddle 15b, and the water passage section is partially blocked with a resin 15a or the like in the small-diameter pipe (water faucet) 15. The water in the pipe is stopped.
The resin 15a used for the water stop portion may be a two-component cured resin or the like. At this time, as shown in FIG. 6A, when the take-out pipe (small-diameter pipe 15 of the water faucet) of the optical fiber sensor 11 is linear, it is difficult to stop the water with the resin 15a. As shown in FIG. 5, a method of forming a water stop portion by the resin 15a by providing an S-shaped curved portion is conceivable.

The deterioration monitoring device 10 of this embodiment has the above-described configuration, and measures damage due to rust or the like of the monitoring tube 2 by the action of the measuring device 12 at an appropriate time. For example, as shown in FIG. 7 (a), if the pipe 2 is in a healthy state, the concave portion 3 due to rust does not occur. However, as shown in FIG. When the recessed part 3 resulting from the thinning accompanying the rust which generate | occur | produces on an outer surface arises, the thickness of the pipe | tube 2 will become thin. For this reason, the stress by water pressure or earth pressure concentrates on the recessed part 3, and distortion becomes large, and a big stress (arrow) arises in the pipe | tube 2 compared with a healthy state.
This stress also affects the optical fiber sensor 11 and the optical fiber sensor 11 is distorted. The degree and position of this strain can be detected by the action of the measuring instrument 12. That is, it is possible to directly monitor the deterioration state of the pipe 2. For this reason, it turns out that the site | part of the pipe line P which embedded the monitoring pipe | tube 2 has deteriorated, and the pipe line connected to the pipe 1 near the site | part and the pipe 1 is replaced | exchanged.

At this time, FIG. 7 shows an image of the strain change in the case of the circumferential strain, but if the strain change can be captured in the healthy state and the deteriorated state, the direction of the strain is not particularly specified.
Moreover, the thickness of the tube 1 can be monitored from the strain value obtained from the monitoring tube 2 by measuring the strain value for each thickness of the tube 1 or the tube 2 and preparing the chart. It is possible to evaluate the risk of water leakage.

Further, the strain can be measured by positively pressurizing the measurement site. For example, as shown in FIG. 9, by loading a balloon 17 into a measurement site from a branch pipe (flange T-shaped pipe) 16 in a pipe P, and supplying the fluid to the balloon 17 from a pump 18 and inflating it. A pressure corresponding to water pressure or earth pressure (arrow in the figure) can be applied to the pipe 2. At this time, the fluid to be supplied is an incompressible fluid such as water in view of the fact that water pressure is acting in the pipe 2, and when assuming a water pipe, for example, water quality sanitation such as tap water. It is desirable to use a fluid that does not cause any problems. Further, by installing a pressure gauge 19 near the pump 18 or in the vicinity of the pump 18 and managing the fluid pressure to be supplied, the load applied to the tube 2 by the balloon 17 can be managed.
As described above, it is possible to measure with higher accuracy by applying a separate constant load to the tube 2 and measuring the strain with respect to the load.

In each of the above embodiments, the optical fiber sensor 11 is attached to the inner surface of the tube 2, but the optical fiber sensor 11 can be attached to the outer peripheral surface of the tube 2. In this case, since the pipe 2 is buried, it is necessary to protect the optical fiber sensor 11 from the surrounding soil. For this reason, for example, it is conceivable to coat the outer surface of the pipe 2 with a protective layer such as a silicone resin having high durability and weather resistance, or a polyurethane resin used for filling joints of buried objects. Further, a method of forming a groove for accommodating the optical fiber sensor 11 on the outer peripheral surface of the tube, sticking the optical fiber sensor 11 in the groove, and filling the groove with a sealing agent or the like can be considered. As the material for filling the groove, a silicone resin having high durability and weathering resistance, a polyurethane resin used for filling a buried object, and the like can be considered. The groove may have a spiral shape or the like (see FIGS. 2A and 5B).
Further, the optical fiber sensor 11 can be attached not only to one of the inner and outer peripheral surfaces of the tube 2 but also to both the inner and outer peripheral surfaces as required.

Of course, the deterioration monitoring device 10 may be provided in the pipe 1 constituting the water pipe P without providing the monitoring pipe 2 separately.
Moreover, it cannot be overemphasized that this invention can be employ | adopted not only to a waterworks pipe line but to a sewer pipe line.
Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

P Water pipe a Detection light (measurement light)
b Reflected light c Reference light 1 Tube (tube)
2 Monitoring tube 3 Recess (Damage due to rust)
DESCRIPTION OF SYMBOLS 11 Distribution measurement type optical fiber sensor 12 Measuring device 13 Pipe inner surface protective layer 14 Connector 15 Extraction pipe 16 Branch pipe (T-shaped pipe with a flange)
17 Balloon 18 Pump 19 Pressure gauge

Claims (9)

  A distributed measurement type optical fiber sensor (11) attached along the inner peripheral surface, outer peripheral surface or inner / outer peripheral surface of the buried water pipe (1), and detection light (a) to the optical fiber sensor (11). And a measuring device (12) for detecting the distortion of the water pipe portion to which the optical fiber sensor (11) is attached by the reflected light (b), and the detected value is obtained by the measuring device (12). A water pipe deterioration monitoring device for measuring the degree of deterioration of the water pipe portion based on the above.   The water pipe deterioration monitoring device according to claim 1, wherein the optical fiber sensor (11) is attached to the inner peripheral surface of the buried water pipe (1) and is covered with a pipe inner surface protective layer (13). .   A monitoring pipe (2) is provided in the buried water pipe (1), and the optical fiber sensor (11) is attached to the monitoring pipe (2), or the optical fiber sensor (11) is attached. The deterioration monitoring device for a water pipe according to claim 1 or 2, which is covered with a pipe inner surface protective layer (13).   The water pipe according to any one of claims 1 to 3, wherein the optical fiber sensor (11) is attached in a wave shape or a spiral shape to the entire circumference of the buried water pipe (1) or the monitoring pipe (2). Deterioration monitoring device.   The deterioration monitoring device for a water pipe according to any one of claims 1 to 4, further comprising a pressurizer for pressurizing a water pipe portion to be measured.   The pressurizer loads the balloon (17) from the branch pipe (16) into the buried water pipe (1) or the monitoring pipe (2), and flows the fluid into the balloon (17). 6. The water pipe deterioration monitoring device according to claim 5, wherein the pressurization is performed.   The buried pipe (1) or the monitoring pipe (2) is provided with a take-out pipe (15) communicating with the inside, and the end of the optical fiber sensor (11) is led out of the take-out pipe (15) to the outside of the pipe, The deterioration of the water pipe according to any one of claims 1 to 6, wherein at the leading end, the measuring device (12) is used to input the detection light (a) and to measure the reflected light (b). Monitoring device.   A distribution measurement type optical fiber sensor (11) is attached to the buried water pipe (1) along the inner peripheral surface, outer peripheral surface or inner and outer peripheral surface, and detection light (a) is input to the optical fiber sensor (11). Then, the water pipe deterioration monitoring method for detecting the distortion of the water pipe portion where the optical fiber sensor (11) is attached by the reflected light (b) and measuring the degree of deterioration of the water pipe portion based on the detected value. .   The method for monitoring deterioration of a water pipe according to claim 8, wherein the water pipe part to be measured is pressurized.

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