JP4236771B2 - Light monitoring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is provided on various objects to be measured including riverbanks and coasts, various levee bodies such as river embankments and seawalls, or other artificial structures, etc. The present invention relates to an optical monitoring device that detects a predictive phenomenon such as a breakdown and contributes to disaster prevention.
[0002]
[Prior art]
For example, in order to avoid disasters caused by collapse and breakage of river embankments such as river embankments and tide embankments, measures such as frequent inspections and the like have been conventionally taken. By the way, river bodies such as river embankments and tide embankments may be scoured by river water currents or ocean waves, etc., and as this scouring progresses, the strength of the levee body is affected, leading to collapse and collapse. there is a possibility. For this reason, if scouring the levee body is discovered by patrol, etc., it is necessary to repair it quickly.
However, it is extremely difficult to perform a thorough inspection by patrol over the entire length of a long riverbank or coast in a short time. Even when levees to be monitored are provided at a plurality of locations on the riverbank or on the coast, it is difficult to make a short inspection due to the travel time between these levee. Moreover, since the geological structure inside the levee body is complex, it may be difficult to see from the outside, such as bottoms that are difficult to see from the outside, and partial sediment runoff inside. Nearly possible. In addition, there are cases in which it is difficult to secure a passage for patrols in a mountainous area, and it is difficult to perform patrols as needed.
In view of this, on river embankments and the like, monitoring facilities such as a water level gauge and ITV (monitoring facility using an imaging device) are installed. These monitoring facilities are widely used to realize constant monitoring and eliminate the labor of patrol.
[0003]
[Problems to be solved by the invention]
However, any of the aforementioned monitoring facilities is limited to the point measurement in the vicinity of the installation position, and the dam body cannot be constantly monitored over a wide range in the longitudinal direction. In particular, a monitoring facility using an imaging device such as ITV has a drawback that the monitoring range is further narrowed under bad weather such as heavy rain. For this reason, in order to monitor over the wide range of the longitudinal direction of a levee body, many expensive monitoring equipment will be installed and cost will become huge.
In addition, the areas that particularly require the installation of monitoring equipment for disaster prevention are often areas where the weather changes rapidly, such as mountainous areas, and various electrical monitoring devices including the ITV mentioned above are caused by lightning strikes, etc. There is also a problem that it is easily damaged by the influence of the induced current.
In addition, scouring that occurs on riverbanks and coasts that do not have a levee body is also required to be monitored as a predictive phenomenon such as large-scale sediment discharge, and the development of technology that can be monitored efficiently at low cost is required. It was done.
[0004]
The present invention has been made in view of the above-described problems, such as riverbanks and coasts, various levee bodies such as river dykes and tide embankments, etc., or displacements generated in various measured objects including other artificial structures. An object of the present invention is to provide a low-cost optical monitoring device that can detect deformation, collapse, etc. over a wide range, is always easy to monitor, and exhibits excellent effects in disaster prevention. .
[0005]
[Means for Solving the Problems]
In order to solve the above problems, in the optical monitoring device of the present invention, for example, an optical fiber sensor is installed by embedding in an object to be measured such as a river bank, a coast, a river dike or a tide embankment, for example, collapse of a dike body by scour The occurrence of displacement, deformation, collapse, etc. of the object to be measured is monitored by detecting that the optical fiber incorporated in the optical fiber sensor has undergone deformation, such as breakage or bending. The breakage or deformation of the optical fiber can be detected from the observation result of the return light of the incident light from the optical pulse tester.
As is well known, when light is incident on an optical fiber, it is caused by light scattering (Rayleigh scattering) due to Fresnel reflected light at a breakage point of the optical fiber or a connector connection point, or a small non-uniformity such as the density of the optical fiber. It is known that backscattered light returns to the incident end of the optical fiber, and the time from when the test light is incident on the optical fiber from the optical pulse tester (so-called OTDR) until the return light is received (hereinafter, By measuring the “return time”), the position of the break point (distance from the optical pulse tester) can be grasped. Usually, only the return light due to light scattering inherent in the optical fiber, such as backscattered light of Rayleigh scattered light, is observed from the optical fiber. For example, when this optical fiber breaks, from the optical pulse tester to the breaking point. The back scattered light of the Rayleigh scattered light and the strong Fresnel reflected light from the breaking point are observed by the optical pulse tester, and the back scattered light of the Rayleigh scattered light from the optical fiber after the breaking point is not observed. Thereby, the break of the optical fiber is detected, and the position of the break point can be grasped from the return time of the return light of the Fresnel reflected light.
Even if the optical fiber is not broken, when the optical fiber is deformed, for example, the optical fiber is bent sharply, and it is possible to detect the bent portion by observing an increase in light loss at the bent portion. is there. In addition, an increase in optical loss is also observed due to the collapse of the optical fiber in the cross-sectional direction. In other words, from the point where the intensity of the return light is observed to be abruptly changed by the optical pulse tester (the return time of the return light to the optical pulse tester) I can grasp.
[0006]
The optical fiber sensor applied to the optical monitoring device of the present invention is, for example, assembled by connecting a plurality of pressure receiving bodies installed in a target monitoring target area set on a bank body to be measured. Due to the displacement, deformation, collapse, etc. of the object to be measured, the optical fiber is deformed such as broken or bent due to the displacement between the adjacent pressure receiving bodies. More specifically, for example, the pressure receiving body displaced due to the movement of earth and sand due to scouring such as a dam body or contact with a water flow and the like and stably held in the earth and sand not affected by scouring Between the pressure receiving bodies, the optical fiber communicated between the pressure receiving bodies is subjected to deformation such as breakage or bending. When the optical fiber of the optical fiber sensor breaks, Fresnel reflected light from the break point is observed, an increase in loss at the bent point, etc. is observed, or return light from the optical fiber after the break point is not observed The displacement, deformation, collapse, etc. of the monitoring target area where this optical fiber sensor is installed are detected. In addition, it is possible to grasp the breaking position of the optical fiber for each boundary between the pressure receiving bodies from the return time of the Fresnel reflected light, etc., so that the occurrence position of the displacement, deformation, collapse, etc. of the monitored region can be determined. It is possible to grasp. Depending on the cross-sectional shape of the broken optical fiber at the breaking point, Fresnel reflected light with sufficient intensity may not be generated, but the presence or absence of return light from the optical fiber after the breaking point and an increase in loss are also observed. Thus, it is possible to reliably grasp the presence / absence of a break point and the presence / absence of an optical fiber deformation portion.
As described above, in the present invention, it is possible to detect the occurrence of displacement, deformation, collapse, etc. in the monitored region by detecting deformations such as the breakage or bending of the optical fiber, and return to the optical pulse tester. By measuring the position of the break point or the bent part of the optical fiber from the light return time or the like, it is possible to grasp the occurrence point of occurrence of displacement, deformation, collapse or the like.
[0007]
By the way, in order to monitor scouring over the entire length of long riverbanks and coasts, for example, if optical fiber sensors are installed along the riverbanks and coasts along the entire length of the river, the scouring after the optical fiber breakage point is performed. Digging detection becomes impossible. In addition, when the area that can be scoured (hereinafter referred to as “monitored area”) is only part of the riverbank, coast or dam body, the optical fiber sensor installed outside the monitored area is wasted. End up. Therefore, in the present invention, it is possible to install a focused optical fiber sensor in a target monitoring target area, and scour monitoring of a plurality of monitoring target areas and the scale of scouring occurring in the monitoring target area. We propose technologies that can be grasped.
[0008]
The invention described in claim 1 is an optical monitoring device that monitors various measured objects including light, such as riverbanks, coasts, river levee and tide embankments, and other artificial structures, It extends substantially along the extending direction of the object to be measured. plural Extending in a direction different from the extending direction of the first optical fiber sensor and the measurement object; Provided at a position corresponding to the first optical fiber sensor. Each of the second optical fiber sensors, and these optical fiber sensors are composed of a plurality of pressure receiving bodies, and the first optical fiber sensor communicates with the plurality of pressure receiving bodies provided continuously in the target monitoring target region. The optical fiber (8a, 8b) is configured to be broken or deformed by displacement between adjacent pressure receiving bodies, and the second optical fiber sensor includes a plurality of pressure receiving pressures connected to the monitored region. The optical fiber communicated with the body is configured to be broken or deformed by the displacement between the adjacent pressure receiving bodies. The optical fibers of the first and second optical fiber sensors are respectively connected to the optical pulse tester. It is connected so that the test light can enter. If breakage or deformation of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber drawn from one end of the first optical fiber sensor, the optical fiber is broken. Test light is incident from the optical pulse tester to the optical fiber of the second optical fiber sensor disposed corresponding to the corresponding first optical fiber sensor in which a deformation or the like is detected. This is an optical monitoring device.
The invention according to claim 2 is an optical monitoring device for monitoring various measurement objects including various bank bodies such as river banks, coasts, river dikes and seawalls, or other artificial structures with light, In the target monitoring target region, the optical fiber (8c, 8d) communicated with a plurality of pressure receiving bodies arranged substantially along the extending direction of the measurement target is broken or deformed by the displacement between the adjacent pressure receiving bodies. Are arranged at a plurality of positions separated from each other in the direction perpendicular to the extending direction of the object to be measured, and the optical fiber of each optical fiber sensor is connected to an optical pulse tester. Is connected so that the test light can enter. If breakage or deformation of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber drawn from one end of the optical fiber sensor, the optical fiber sensor On the other hand, the test light of the optical pulse tester is incident on an optical fiber drawn into another optical fiber sensor provided in a direction perpendicular to the extending direction of the object to be measured. ing This is an optical monitoring device.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an optical monitoring device of the present invention (hereinafter abbreviated as “monitoring device” in the embodiments of the invention) will be described.
Note that the monitoring devices of the following first to third embodiments are all for scour monitoring of a river levee that is a measurement target.
[0010]
(First embodiment)
In FIG. 1, reference numeral 1 is a monitoring device of this embodiment, 2 is an optical pulse tester ("OTDR" in FIG. 1), 3 is a connection unit (in this embodiment, an optical termination box), and 4 is an optical fiber. Sensors 5 are core wire selectors (light SW in FIG. 1), and 6 is a river.
In this monitoring apparatus 1, a plurality of optical fiber sensors 4 are embedded in a monitoring target area 7 a that is particularly easily scoured on a river dike 7 provided along a river 6, and an optical fiber 8 incorporated in each optical fiber sensor 4. Are connected to the optical fiber 9 (optical cable) connected to the optical pulse tester 2 via the connection unit 3.
For example, a single mode optical fiber having a core diameter of several μm to 10 μm and a diameter of 125 μm is employed as an optical fiber incorporated in the optical fiber sensor of each of the following embodiments. Further, as the OTDR which is the optical pulse tester 2, for example, a high resolution type having a test light wavelength of 1310 nm, a pulse width of 10 ns or more (as fine as possible) and a spatial resolution of 2 m or more (as short as possible) is adopted.
[0011]
The optical fiber sensor 4 has a structure in which a plurality of pressure receiving bodies 4a embedded in the soil of the monitoring target area 7a are connected in series, and the optical fiber 8 is connected so as to pass through these pressure receiving bodies 4a. Between the pressure receiving body 4a displaced with the movement of the earth and sand by the scouring of the target area 7a, the contact with the water flow, etc., and the pressure receiving body 4a stably held in the sand without being affected by the scouring The optical fiber 8 is easily broken or deformed.
The following will be described by taking a break as an example.
In FIG. 1, each of the optical fiber sensors 4 has two pressure receiving bodies 4 a, but may be three or more, and the number of the pressure receiving bodies 4 a may be different for each optical fiber sensor 4. May be. The optical fiber 8 has a structure in which a single-core optical fiber or the like is easily broken between the pressure receiving bodies 4a. Further, the exposed portion connected to the connection unit 3 is an optical cable in which waterproofness is ensured by a resin sheath. In addition, each pressure receiving body 4a stores the extra length of the optical fiber 8 in a curved manner while ensuring the waterproofness inside. Needless to say, the optical fiber 8 communicated between the pressure receiving bodies 4a is also waterproof.
[0012]
The connection unit 3 can branch-connect a plurality of optical fibers 8 on the optical fiber sensor 4 side (four in FIG. 1) to the single optical fiber 9 on the optical pulse tester 2 side. . A single optical fiber 9 on the optical pulse tester 2 side is branched into a plurality of optical fibers 11 by an optical branching element 10 (optical coupler) housed in the connection unit 3. The connector is connected by the optical fiber 8 on the fiber sensor 4 side and the optical connectors 11a and 8a. Since the optical fiber 8 of the optical fiber sensor 4 is terminated by an optical connector 8a so that the connector can be connected, the optical pulse test can be performed simply by connecting the connector to the optical fiber 11 in the connection unit 3 after installation in the monitoring target area 7a. It can be easily connected to the optical fiber 9 on the side of the container 2 and has excellent workability. FIG. 1 shows a state in which three single-core optical fibers 8 on the optical fiber sensor 4 side are connected to one optical fiber 9 on the optical pulse tester 2 side, and the remaining one light By using the fiber 11, one optical fiber sensor 4 can be added.
[0013]
In order to monitor the scouring of the monitoring target region 7a, the test light is incident on the optical fiber 9 selected by the core selection device 5 from the optical pulse tester 2, and the return light is observed. When there is no occurrence of scouring or the like and there is no break point in the optical fiber 8 of the optical fiber sensor 4, the return light from the entire length of all the optical fibers 8 connected to the optical fiber 9 is the same optical fiber. 9 is received and observed by the optical pulse tester 2. As long as the optical fiber 8 is not deformed such as bending or crushing, the optical pulse tester 2 stably observes the backscattered light of Rayleigh scattered light unique to the optical fiber 8 from the entire length of the optical fiber 8.
[0014]
Here, the plurality of optical fibers 8 connected to the same optical fiber 9 are made different in the optical pulse tester 2 by making the lengths different from each other by, for example, the extra length secured in the connection unit 3. Can be distinguished.
As an example, the detection of breakage of four optical fibers 8 branched and connected to the same optical fiber 9 by the optical branching element 10 of the connection unit 3 will be described with reference to FIGS. I will explain. In FIG. 2A, for convenience, the reference numerals 81, 82, 83, and 84 are assigned to distinguish the four optical fibers 8. Of these optical fibers, the optical fiber 81 is the shortest, and the optical fibers 82, 83, and 84 are longer in the following order.
[0015]
The return light of the incident light to each optical fiber 8 is synthesized and observed by the optical pulse tester 2 (“OTDR” in FIG. 2A). Since the return light from each of the optical fibers 81 to 84 includes noise or the like, it is preferable to repeatedly observe the return light and adopt an average value (so-called averaging process). In FIG. 2A, the extra lengths 8 e of the optical fibers 81 to 84 are described with their positions shifted from each other, but these extra lengths 8 e are actually stored in the connection unit 3. The optical fibers 81 to 84 are made different from each other in the length of the extra length 8e accommodated in the connection unit 3 so that the difference in the end position farthest from the optical pulse tester 2 becomes clear. That is, the length of each optical fiber 8 is adjusted by the extra length 8e so that the difference in the terminal position of each optical fiber 81-84 is clearly distinguished corresponding to the spatial resolution of the optical pulse tester 2. The extraction lengths of the optical fibers 81 to 84 from the connection unit 3 (extraction lengths from the extra length 8e of the optical fibers 81 to 84 to the right side in FIG. 2A) may be constant or different from each other. FIG. 2 illustrates the case where it is constant.
[0016]
As shown in FIG. 2 (b), in the initial state where no breakage or the like exists in each of the optical fibers 81 to 84, the optical pulse tester 2 produces a composite waveform of the return light from each of the optical fibers 81 to 84. Strong Fresnel reflected light from the ends of the optical fibers 81 to 84 is shown as peak waveforms 81a to 84a (hereinafter referred to as “Fresnel waveform”).
For example, when the optical fiber 82 is broken, as shown in FIG. 2 (c), the optical pulse tester 2 shows a Fresnel waveform 82b corresponding to the Fresnel reflected light from the broken portion, and the optical fiber 82 is terminated. The corresponding Fresnel waveform 82a is not observed. As a result, it is specified that the newly observed Fresnel waveform 82 b is generated by the breakage of the optical fiber 82.
Further, for example, when the optical fiber 83 breaks at the same position as the end of the optical fiber 82 (the optical path length from the optical pulse tester 2 is the same), the Fresnel waveform observed by the optical pulse tester 2 is Although the position is the same as the Fresnel waveform 82a at the end of the optical fiber 82, since the Fresnel waveform 83a corresponding to the Fresnel reflected light from the end of the optical fiber 83 is not observed, the breakage of the optical fiber 83 can be confirmed.
[0017]
Confirmation of the position of the breakage point of each optical fiber 81-84 and calculation of the distance from the optical pulse tester 2 are, for example, from the Fresnel waveforms 81a-84a corresponding to the end of each optical fiber 81-84 before the occurrence of breakage, It is obtained by calculating the distance (time) to the Fresnel waveform newly observed by the break.
In addition, the extra length 8e of each optical fiber 81-84 is adjusted, the return light from the part pulled out from the connection unit 3, or the return light from the part inserted in the pressure receiving body 4a of the optical fiber sensor 4, The optical pulse tester 2 may be observed so as not to overlap each other. In this case, it is easier to identify the optical fibers 81 to 84 that have broken. Even when a plurality of optical fibers 8 are broken at the same time, the position of each broken portion and the distance from the optical pulse tester 2 can be easily grasped for each optical fiber 8.
[0018]
The observation data of the return light from the optical pulse tester 2 is stored and displayed by the control device 12 connected to the optical pulse tester 2. The control device 12 includes a control unit that controls driving of the optical pulse tester 2, the core selection device 5, and the like, a storage unit that stores observation data of return light incident on the optical path, and a display that displays the observation data. And an alarm output unit that issues an alarm when a break of the optical fiber 8 of the optical fiber sensor 4 is detected from the observation data.
[0019]
When the monitoring object region 7a is scoured, a displacement occurs between the pressure receiving bodies 4a of the optical fiber sensor 4, and when the optical fiber 8 is broken, a strong Fresnel reflected light from the breaking point is observed by the optical pulse tester 2. As a result, the breakage of the optical fiber 8 is detected, and thus the scouring of the monitoring target region 7a can be detected.
[0020]
Since each of the optical fiber sensors 4 installed in the same monitoring target area 7a is continuously provided at intervals of several tens to several hundreds of meters in the longitudinal direction of the river bank 7, the optical fiber sensors 4 that detect scouring are provided. The scouring position in the longitudinal direction of the river bank 7 is specified by the specification. When a plurality of optical fiber sensors 4 detect scouring, the vicinity of each optical fiber sensor 4 or along the extending direction of the river levee 7 in the continuous scouring range including these optical fiber sensors 4 The dimension (scouring width) is detected.
[0021]
In FIG. 1, the pressure receiving bodies 4 a of the optical fiber sensors 4 installed in the monitoring target region 7 are connected in series in a direction substantially perpendicular to the extending direction of the river bank 7, that is, in a direction substantially perpendicular to the river 6. Therefore, when the breakage of the optical fiber 8 between the pressure receiving bodies 4a is observed, it is detected that scouring has progressed to the position of the boundary between the pressure receiving bodies 4a. 7 scouring depth can be grasped. If the number of pressure receiving bodies 4a of the optical fiber sensor 4 is increased and the distance between the boundaries between the pressure receiving bodies 4a is shortened, the scouring depth of the monitored region 7 can be grasped more precisely. Is possible. However, an extra length of the optical fiber 8 is secured in each pressure receiving body 4a so that the boundary position between the pressure receiving bodies 4a can be distinguished on each reflected waveform in accordance with the resolution of the optical pulse tester 2. It is necessary to keep.
[0022]
According to this monitoring apparatus 1, the optical fiber 8 of the optical fiber sensor 4 can be easily connected to the optical fiber 9 on the optical pulse tester 2 side by connector connection in the connection unit 3 installed in the vicinity of the monitoring target area 7a. It is easy to focus on the plurality of optical fiber sensors 4 in the monitoring target area 7a. Since it is not necessary to install the optical fiber sensor 4 in the long river dike 7 where scour monitoring is unnecessary, the cost can be reduced and the construction is easy.
[0023]
In the monitoring device 1, the optical fiber test is performed while switching the connection of the optical fiber 9 to the optical pulse tester 2 in order by the core selection device 5, and the breakage of the optical fiber 8 of each optical fiber sensor 4 is monitored. Since this monitoring operation is repeatedly and continuously performed for all the optical fibers 9, each monitoring target area 7a is substantially constantly scoured and monitored. In addition, the monitoring of each monitoring target area can be performed from a safe place that is not affected by the weather or the like and is not dangerous even if the river levee 7 collapses, etc., so that the monitoring efficiency can be dramatically improved. .
[0024]
Further, in the configuration in which a plurality of optical fibers 8 on the optical fiber sensor 4 side are connected to the single optical fiber 9 on the optical pulse tester 2 side by the optical branching element 10, one measurement time for the optical fiber 9 is measured. The number of switching connection of the optical fiber 9 by the core selection device 5 can be reduced, and it is necessary to monitor all the optical fiber sensors 4 of the monitoring device 1. The scan time can be shortened, and the time lag between scouring occurrence and scour detection can be shortened.
In addition, the connection between the optical fiber 8 of each optical fiber sensor 4 and the optical pulse tester 2 is not limited to the configuration via the optical branching element 10, and for example, a multi-core optical cable on the optical pulse tester 2 side. One core of the optical fiber 8 on the side of the optical fiber sensor 4 is connected to one core of the optical fiber sensor 4 by connector connection or fusion splicing. In the core selection device 5, the optical pulse tester 2 is connected to each optical fiber of the optical cable. It is also possible to adopt a configuration for switching the connection to the. In this configuration, there is an advantage that the length adjustment and the like for distinguishing each optical fiber sensor 4 can be omitted, and the construction becomes easy. However, since the scan time required for monitoring all the optical fiber sensors 4 becomes long, it is preferable to adopt a configuration using the optical branching element 10 in order to shorten the scan time.
[0025]
In the present embodiment, an example in which scouring detection is performed by detecting breakage of the optical fiber 8 has been described. However, bending, crushing, or the like generated in the optical fiber 8 due to displacement between the pressure receiving bodies 4a when scouring occurs. It is also possible to detect scouring by detecting deformation. The OTDR which is the optical pulse tester 2 can detect from the intensity of the return light from the optical fiber 8 that the optical loss of the optical fiber 8 has increased due to bending or crushing other than breakage. The position (distance from the optical pulse tester 2) where the return light intensity has changed can be grasped by measuring from the return time of the return light. Thereby, the presence or absence of scouring and the position of the scouring location can be grasped similarly to the detection of the breaking point. The difference from the detection of the break point is that the return light from the optical fiber after the location where bending or crushing occurred (the optical fiber at a location farther from the optical pulse tester 2 than the location where bending or crushing occurred) is also observed. (This return light may not be observed in some cases.) Otherwise, it is the same as the break point detection.
In the optical pulse tester 2, either Fresnel reflected light due to the occurrence of a break point or an increase in loss due to non-breaking deformation such as bending or crushing is observed. Similarly, at the location described, it is possible to detect scouring and grasp the scouring occurrence position from observation data of optical loss increase due to bending or crushing of the optical fiber.
[0026]
(Second embodiment)
A second embodiment of the present invention will be described below with reference to FIGS.
3 and 4 are plan views showing the entire monitoring device 20 of the present embodiment. FIG. 3 shows a normal monitoring state before scouring detection, and FIG. 4 shows a monitoring state after scouring detection.
3 and 4, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be simplified.
[0027]
In this monitoring device 20, a first optical fiber sensor 21 extending substantially along the extending direction of the river dike 7 and a second optical fiber sensor 22 extending in a direction substantially perpendicular to the extending direction of the river dike 7 are respectively provided. A plurality are embedded in the monitoring target area 7a. A plurality of first optical fiber sensors 21 are connected in series along the extending direction of the river dike 7 in the monitoring target area 7 a, and the second optical fiber sensors 22 are more than the first optical fiber sensors 21. A plurality of lines are arranged in parallel at intervals of, for example, several tens to several hundreds of meters along the extending direction of the river 6 at a location slightly away from the river 6.
[0028]
The second optical fiber sensor 22 is the same as the optical fiber sensor 4 described in the first embodiment, and has a structure in which the optical fiber 8 is communicated with a plurality of pressure receiving bodies 4a that are arranged in series. The optical fiber 8 of the second optical fiber sensor 22 is connected to the single optical fiber 9 on the optical pulse tester 2 side via an optical branching element 10 (not shown in FIG. 3) built in the connection unit 3. A plurality of branch connections are made (5 branches in this embodiment). A plurality of second optical fiber sensors 22 disposed in the vicinity of the first optical fiber sensor 21 are branched from the same optical fiber 9 via the same connection unit 3.
[0029]
The first optical fiber sensor 21 has a structure in which an optical fiber 8a is inserted from one end to the other end of a plurality of pressure receiving bodies 4b connected in series, and an optical fiber 8b is inserted from the other end to one end. ing. That is, the first optical fiber sensor 21 accommodates two optical fibers. The optical fibers 8a and 8b of the first optical fiber sensor 21 are connected to the optical fiber in the optical cable 9a, which is a multi-core optical fiber on the optical pulse tester 2 side, via the connection unit 3. It is 1: 1 with no optical branching element.
Connection of the optical fiber 9 and each optical fiber of the optical cable 9 a to the optical pulse tester 2 is switched by the core selection device 5.
[0030]
The scour monitoring of the river bank 7 by the monitoring device 20 is first performed by monitoring the break of the optical fiber 8a of the first optical fiber sensor 21 by the optical pulse tester 2 when scouring is not detected. That is, only the optical fiber of the optical cable 9a that is connected to the optical fiber 8a is selected by the core selection device 5, and the return light of the incident light is observed while switching the connection with the optical pulse tester 2. Monitor for breakage. There is no test light incident on the optical fiber 8 b of the first optical fiber sensor 21 and the optical fiber 8 of the second optical fiber sensor 22. The optical line indicated by the solid line in FIG. 3 is in a monitoring state where test light is incident, and the optical line indicated by the broken line in FIG. 3 is in a dormant state not used for monitoring.
[0031]
The optical pulse test is performed in order, for example, from the optical fiber 8a of the optical fiber sensor 21 on the left side in FIG. 3 to the optical fiber 8a of the optical fiber sensor 21 on the right side. Since the process is automatically repeated, the scouring of the monitoring target area 7a in the vicinity of each optical fiber sensor 21 is constantly monitored. Further, since the test light is incident only on the optical fiber 8a of the first optical fiber sensor 21 and the number of optical lines is reduced, the switching connection of the all optical fibers 8a to the optical pulse tester 2 by the core selection device 5 is performed. The scan time required for the scouring can be shortened, and as a result, the time lag between scouring occurrence and scouring detection can be reduced.
[0032]
Until the breakage of the optical fiber 8a is detected, the breakage monitoring of the optical fiber 8a is continued. If the breakage of the optical fiber 8a is detected, the fact that scouring has occurred is shown in FIG. As described above, the optical fiber 8b of the corresponding first optical fiber sensor 21 where the optical fiber 8a is detected to be broken is also monitored for breakage by observing the return light of the incident light from the optical pulse tester 2 (both ends monitoring). Mode), and the optical fiber 8 of each second optical fiber sensor 22 corresponding to the first optical fiber sensor 21 that has detected scouring is similarly observed by the return light observation of the incident light from the optical pulse tester 2. Breakage monitoring is performed (monitoring mode).
[0033]
The pressure receiving body 4b of the first optical fiber sensor 21 is continuously provided along the extending direction (longitudinal direction) of the river bank 7 and the pressure receiving body 4a of the second optical fiber sensor 22 extends in the extending direction of the river bank 7a. In this monitoring device 20, the first optical fiber sensor 21 detects the scouring width of the river levee 7 (the scouring range in the longitudinal direction of the river levee 7), and the second optical fiber. The sensor 22 detects the scouring depth of the river dike 7 (the scouring depth perpendicular to the longitudinal direction of the river dike 7).
[0034]
In the first optical fiber sensor 21, the breaking position of the optical fiber 8a caused by the displacement between the pressure receiving bodies 4b due to the movement of earth and sand accompanying the scouring generated in the river bank 7 or contact with the water flow, and the breaking of the optical fiber 8b. The scour width is detected by measuring each position. For example, when the breaking positions of the optical fibers 8a and 8b of the specific first optical fiber sensor 21 are different, the scouring range is between the breaking positions of the optical fibers 8a and 8b, and the distance between the breaking positions is the scouring distance. Width.
Further, when scouring occurs in a wide area extending over the plurality of first optical fiber sensors 21, by grasping the breaking positions of the optical fibers 8a and 8b of the first optical fiber sensor 21 at both ends of the scouring range, The scour width can be grasped. At the end of the scouring area in the river bank 7 extending direction, one of the optical fibers 8a, 8b of the first optical fiber sensor 21 is in the same position as the end of the scouring area in the river bank 7 extending direction. The fracture positions of the other optical fibers 8a and 8b are the ends of the first optical fiber sensor 21. In the first optical fiber sensor 21 positioned between the first optical fiber sensors 21 at both ends of the scouring range, all the pressure receiving bodies 4b are displaced due to movement of earth and sand accompanying scouring, contact with water flow, etc. The optical fibers 8a and 8b are broken at the end of the first optical fiber sensor 21, respectively.
[0035]
On the other hand, the second optical fiber sensor 22 measures the breaking position of the optical fiber 8 caused by the displacement between the pressure receiving bodies 4a due to the movement of earth and sand accompanying the scouring generated on the river bank 7 or contact with the water flow. Can grasp the scouring depth. The break monitoring of the optical fiber 8 of the second optical fiber sensor 22 is performed on the optical fiber 9 to which a plurality of second optical fiber sensors 22 installed corresponding to the first optical fiber sensor 21 that has detected scouring are connected. And the presence or absence of breakage of the optical fiber 8 of each second optical fiber sensor 22 and the breakage position are simultaneously detected. By grasping the scouring depth by each of the plurality of second optical fiber sensors 22 provided corresponding to the same first optical fiber sensor 21, the vicinity of the first optical fiber sensor 21 in which the scouring is detected is detected. The distribution of the scouring depth in the extending direction of the river bank 7 in the monitoring target area 7a can be grasped. The plurality of optical fibers 8 connected to the same optical fiber 9 can be distinguished from each other by the extra length secured in the connection unit 3 and the break position of each optical fiber 8 can be distinguished and grasped. it can.
[0036]
The first and second optical fiber sensors 21 and 22 are configured such that the optical fibers 8, 8a, and 8b are broken at the boundary between the pressure receiving bodies 4a and the pressure receiving bodies 4b. By narrowing the arrangement pitch of 4b and shortening the distance between the boundaries between the pressure receiving bodies 4a and 4b, the detection accuracy of the scouring width and scouring depth can be improved.
[0037]
After scouring is detected by monitoring the breakage of the optical fiber 8a of the first optical fiber sensor 21, the optical fiber 8a of each first optical fiber sensor 21 and the optical fiber of the first optical fiber sensor 21 that has entered both-end monitoring mode. 8a, 8b, one optical fiber 9 to which the optical fiber 8 of each second optical fiber sensor 22 corresponding to the first optical fiber sensor 21 (the second optical fiber sensor 22 entering the monitoring mode) is connected. Are switched and connected to the optical pulse tester 2. Specifically, for example, in the order of monitoring the breakage of the optical fibers 8a performed in sequence, the breakage of the optical fiber 8b of the first optical fiber sensor 21 related to the optical fiber 8a is next to the breakage of the detected optical fiber 8a. After the monitoring and the break monitoring of the optical fiber 8 of the plurality of second optical fiber sensors 22 arranged corresponding to the first optical fiber sensor 21, the process proceeds to the next break monitoring of the optical fiber 8a.
[0038]
The breakage monitoring of the optical fiber 8 of the second optical fiber sensor 22 may be performed only for the second optical fiber sensor 22 corresponding to the first optical fiber sensor 21 that has detected scouring. Since the breakage monitoring of the optical fiber 8 is performed collectively by the test light entering the optical fiber 9 to which the optical fiber 8 is connected, the number of optical lines to which the test light is incident can be reduced as much as possible. The scan time required for monitoring the optical fibers 8, 8a, 8b of all the optical fiber sensors 21, 22 of the apparatus 20 can be shortened, and thereby the time lag between scouring occurrence and scour detection can be minimized.
Even after the scouring is detected, the break monitoring of the optical fibers 8, 8a, 8b is continuously and repeatedly performed by the switching connection of the optical line by the core selection device 5 and the incidence of the test light from the optical pulse tester 2. Therefore, the progress of scouring over time can be grasped in real time.
[0039]
When new scouring detection by the first optical fiber sensor 21 occurs, in the same manner as described above, between the optical fiber 8a in which the breakage is detected and the optical fiber 8a to be monitored next, Breakage monitoring of the optical fiber 8b of the first optical fiber sensor 21 and monitoring of the breakage of the optical fiber 8 of the plurality of second optical fiber sensors 22 arranged corresponding to the first optical fiber sensor 21 are interrupted. Correspond with. The increase in the number of optical lines to be monitored is automatically made by the drive control of the optical pulse tester 2 and the core selection device 5 by the control device 12.
[0040]
(Third embodiment)
Next, a monitoring device 30 according to a third embodiment of the present invention will be described with reference to FIGS.
In the figure, the same components as those in FIGS. 3 and 4 are denoted by the same reference numerals, and the description thereof will be simplified.
[0041]
As shown in FIG. 3, in this monitoring device 30, optical fibers 8 c and 8 d are attached to a pressure receiving body 4 b that is continuously provided along the extending direction of the river bank 7 in the target monitoring target area 7 a of the river bank 7. Are connected to each other, and the primary and secondary optical fiber sensors 31 and 32 configured such that the optical fibers 8c and 8d are broken by the displacement between the adjacent pressure receiving bodies 4b are connected to the river bank 7 in the extending direction. Are arranged at a plurality of locations separated from each other in a direction perpendicular to the direction (directions where the distance from the river 6 is different). The optical fibers 8c and 8d of the optical fiber sensors 31 and 32 are respectively connected to the optical cable 9b, which is an optical fiber on the optical pulse tester 2 side, in the connection unit 3 installed for each of the primary and secondary optical fiber sensors 31 and 32. One-to-one connectors are connected to the 9c optical fiber.
The optical fiber 8c is communicated from one end in the longitudinal direction of the primary and secondary optical fiber sensors 31 and 32 toward the other end, and the optical fiber 8d is directed from the other end to the one end in the primary and secondary optical fiber sensors 31 and 32. Communicated.
[0042]
In this embodiment, a plurality of primary and secondary optical fiber sensors 31 and 32 are connected in series along the river bank 7 in the monitoring target area 7a. However, the installation positions of the primary and secondary optical fiber sensors 31 and 32 correspond to each other in the extending direction of the river embankment 7, and are different only in the direction perpendicular to the extending direction of the river embankment 7. The primary optical fiber sensor 31 is installed closer to the river 6 than the secondary optical fiber sensor 32.
[0043]
Each optical fiber sensor 31 and 32 is communicated between these pressure receiving bodies 4b when displacement occurs between the adjacent pressure receiving bodies 4b due to the movement of earth and sand accompanying the scouring of the monitoring target region 7a or contact with the water flow. The optical fibers 8c and 8d are broken. By detecting the breakage of the optical fibers 8c and 8d by the optical pulse tester 2, scouring of the monitoring target region 7a is detected. When the optical fibers 8c and 8d are broken, strong Fresnel reflected light is observed from the break points of the optical fibers 8c and 8d, and return light from the optical fibers 8c and 8d after the break point is observed from the optical pulse tester 2. It is detected because it disappears. Further, the break position (distance from the optical pulse tester 2) can be grasped from the return time of the return light such as Fresnel reflected light.
[0044]
In this monitoring device 30, first, as shown in FIG. 5, only one optical fiber 8c of the primary optical fiber sensor 31 is monitored for breakage, and if the breakage of this optical fiber 8c is detected, scouring is performed. As shown in FIG. 6, the optical fiber 8d of the primary optical fiber sensor 31 that has detected scouring and a secondary optical fiber sensor provided at a position corresponding to the primary optical fiber sensor 31 are recognized. Breakage monitoring is started for one of the optical fibers 8c.
[0045]
As shown in FIG. 5, before the scouring detection by the primary optical fiber sensor 31, the connection of one optical fiber 8 c of each primary optical fiber sensor 31 to the optical pulse tester 2 is switched in turn by the core selection device 5. A light pulse test is performed while being monitored for the presence or absence of breakage. At this time, the test light is not incident on the other optical fiber 8d of the primary optical fiber sensor 31 and the optical fibers 8c and 8d of the secondary optical fiber sensor 32, and no breakage monitoring is performed.
When a break is detected in the optical fiber 8c of the primary optical fiber sensor 31, for example, after the test light is incident on the optical fiber 8c in which the break is detected, the other of the primary optical fiber sensor 31 into which the optical fiber 8c is drawn The optical fiber 8d of the primary optical fiber sensor 31 is monitored for breakage, and the optical fiber 8c of the secondary optical fiber sensor 32 corresponding to the primary optical fiber sensor 31 is monitored for breakage. Transition.
[0046]
When rupture monitoring of the optical fibers 8c and 8d drawn from both ends of the primary optical fiber sensor 31 is performed (both ends monitoring mode), the scouring width of the monitoring target region 7a can be grasped. That is, in the primary optical fiber sensor 31 that has entered the both-end monitoring mode, the scouring width can be grasped by measuring the breaking position of the optical fiber 8c and the breaking position of the optical fiber 8d. For example, when the scouring range of the monitoring target area 7a is within the extension range of the specific primary optical fiber sensor 31, the area between the break positions of these optical fibers 8c and 8d is the scouring area. Is the scour width. Further, when the scouring range extends over a plurality of primary optical fiber sensors 31, the breaking positions of the optical fibers 8c and 8d of the primary optical fiber sensors 31 at both ends of the scouring range are measured, and the distance between the farthest breaking positions is determined. By grasping, the scour width can be grasped. At the riverbank 7 extending direction end of the scouring area, one break position of the optical fibers 8c, 8d of the primary optical fiber sensor 31 coincides with the river bank 7 extending direction end of the scouring area, The fracture position of the other optical fibers 8c and 8d is the end of the primary optical fiber sensor 31. In the primary optical fiber sensor 31 positioned between the primary optical fiber sensors 31 at both ends of the scouring range, all the pressure receiving bodies 4b are displaced by the movement of earth and sand accompanying the scouring, contact with the water flow, etc. The fiber sensor 31 is broken at both ends.
[0047]
The secondary optical fiber sensor 32 that has started the break monitoring (monitoring mode) of one optical fiber 8c also starts the break monitoring of the other optical fiber 8d when the break of the optical fiber 8c is detected. It is supposed to enter. If a breakage is detected in the optical fiber 8c of the secondary optical fiber sensor 32, it can be understood that the scouring depth of the monitoring target area 7a reaches the secondary optical fiber sensor 32. Even if scouring is detected by the primary optical fiber sensor 31, if no breakage is detected in the optical fiber 8c of the secondary optical fiber sensor 32 corresponding to the scouring, the scouring depth of the monitored region 7a is the secondary light. It can be understood that the fiber sensor 32 has not been reached.
[0048]
If a tertiary optical fiber sensor having the same structure as the primary and secondary optical fiber sensors 31 and 32 is installed in parallel to the river bank 7 at a location further away from the river 6 than the secondary optical fiber sensor 32, Can also detect large scouring depths. The primary and secondary optical fiber sensors 31 and 32 (including the tertiary optical fiber sensor and the fourth optical fiber sensor installed in parallel to these) are perpendicular to the extending direction of the river bank 7 An optical fiber sensor (for example, the second optical fiber sensor described in the second embodiment) extending in the vicinity of the primary and secondary optical fiber sensors 31 and 32 and extending perpendicularly to the river bank 7 extending direction. If 22) is installed, the detection accuracy of the scouring depth of the monitoring target area 7a can be further improved.
[0049]
According to this monitoring device 30, the optical fiber sensors 31, 32 in which a plurality of pressure receiving bodies 4b for breaking the optical fibers 8c, 8d are continuously provided along the extending direction of the river bank 7 are provided in the target monitoring target region 7a. As a result, the scouring range (scouring width and scouring depth) of the monitoring target area 7a can be efficiently grasped by connecting a plurality of lines in a direction perpendicular to the river dike 7 extending direction and the river dike 7 extending direction. . Only two optical fibers are required for scour monitoring of each of the optical fiber sensors 31, 32, and the primary optical fiber sensor 31 that enters the both-end monitoring mode at the time of scour detection detects that one of the optical fibers 8c is broken. The secondary optical fiber sensor 32 that is only the primary optical fiber sensor 31 and enters the monitoring mode when scouring is detected is a secondary optical fiber sensor corresponding to the primary optical fiber sensor 31 in which the breakage of the optical fiber 8c is detected. Since only 32, the number of optical lines to be monitored by the optical pulse tester 2 can be suppressed both before and after scour detection. For this reason, the scan time required for monitoring all the optical lines to be monitored can be shortened, and the time lag between scouring occurrence and scour detection can be reduced. Moreover, the optical fiber 8c of the primary optical fiber sensor 31 before scouring detection is monitored for breakage, and the optical fiber 8c, 8d of the primary optical fiber sensor 31 after scouring detection and the optical fiber 8c of the secondary optical fiber sensor 32 are monitored. In addition, the detection of the break position is repeatedly performed in order while the connection to the optical pulse tester 2 is switched by the core selection device 5, so that the progress of scouring of the monitoring target region 7a can be observed over time. .
[0050]
As described in each of the above-described embodiments, the monitoring apparatus according to the present invention connects the optical fiber of the optical fiber sensor installed in the monitoring target region that needs to be monitored to the optical fiber on the optical pulse tester side. Therefore, it is possible to focus on the monitoring target area. On the other hand, since it is not necessary to install an optical fiber sensor outside the monitoring target region, it is easy to shorten the construction period and reduce the cost. Even if the monitored area is scattered at multiple locations along the river bank, etc., it can be easily assembled simply by connecting the optical fiber on the optical fiber sensor side installed here with the optical fiber on the optical pulse tester side. it can. Since an optical fiber sensor can be obtained at a low cost, it is possible to significantly reduce costs compared to the case where many expensive facilities such as ITV are installed, and a wide range of monitoring and monitoring at a plurality of locations can be realized at a low cost. . In addition, this monitoring device directly monitors the movement of earth and sand on the monitored ground and the water flow that has entered the scouring site by using an optical fiber sensor installed in the ground to be monitored. The occurrence of scouring at the bottom and inside of the river dike, which cannot be confirmed with, can be detected reliably, and can be used for disaster prevention.
In addition, this monitoring device has no electrical operating part other than the optical pulse tester, and since there is no fear of being affected by the induced current due to lightning strikes, etc., only the optical pulse tester and its attached instrument are induced currents. If it is protected so as not to be affected by lightning, even if it is installed in a mountainous area where lightning is likely to occur, the monitoring performance will not be impaired, and the degree of freedom of installation location will be greatly improved.
[0051]
In the monitoring apparatus described in each of the above-described embodiments, when test light is incident on the optical fiber of the optical fiber sensor, it is from a connector connection portion or the like that exists between the optical pulse tester and the optical fiber of each optical fiber sensor. Fresnel reflected light is observed. However, if Fresnel reflected light from a location where there is no connector connection or the like is observed, a disconnection of the optical line has been detected. At this time, since the disconnection position (distance from the optical pulse tester) can be grasped from the return time of the Fresnel reflected light, it can be quickly recovered. Further, when no return light from the optical line far from the optical pulse tester after the connector connection point is observed, the connector connection may be released. Also in this case, since the location where the defect occurs can be easily grasped from the return time of the return light, it can be quickly recovered. Thus, this monitoring device is excellent in maintainability.
[0052]
In addition, this invention is not limited to the said embodiment, For example, it cannot be overemphasized that the structure of an optical fiber sensor part, a connection unit, etc. can be changed suitably.
The application target of the optical monitoring device of the present invention is not limited to a bank body such as a river embankment, and various measured objects such as riverbanks and coasts themselves, various embankments facing rivers and seas, cliffs, artificial structures, etc. It is possible to detect signs such as collapse due to scouring and natural collapse.
In any of the above-described embodiments, the configuration in which the optical fiber sensor is embedded in the monitoring target area is illustrated. However, the present invention is not limited to this. For example, the anchor fixed to the earth and sand in the monitoring target area It is also possible to adopt a configuration in which the movement of the earth and sand is transmitted to the pressure receiving body in connection with.
Connection between the optical fibers 8a and 8b of the first optical fiber sensor 21 of the second embodiment and the optical fiber on the optical cable 9a side, optical fibers 8c and 8d of the primary and secondary optical fiber sensors 31 and 32 of the third embodiment, and The connection with the optical fiber on the optical cable 9b, 9c side is not limited to one-to-one. For example, the optical cable 9a, 9b, 9c side is connected to the optical fiber via the optical splitter (optical coupler) built in the connection unit 3. Alternatively, a plurality of lines may be connected. At this time, the plurality of sensor-side optical fibers connected to the optical fibers on the optical cables 9a, 9b, 9c side have different lengths depending on the extra length secured in the connection unit 3, etc. , So that you can distinguish.
[0053]
The optical fiber sensor 21 according to the second embodiment and the optical fiber sensors 31 and 32 according to the third embodiment together with the optical pulse tester 2 constitute a monitoring device according to claim 2. The monitoring device according to claim 2 is not limited to the configuration described in each of the embodiments. For example, a configuration in which only the optical fiber sensor extended along the river bank is connected to the optical pulse tester side, etc. It can be adopted. In any configuration, with this monitoring device, it is possible to grasp the scouring position and the scouring width of the monitoring target area along the extending direction of the bank body or the like. The scour width can be easily grasped from, for example, the scour detection positions of a plurality of optical fiber sensors.
[0054]
In the monitoring device according to the third embodiment (corresponding to the monitoring device according to the invention described in claim 5), when the primary optical fiber sensor 31 on the side near the river detects scouring, the scouring is detected correspondingly. The configuration of starting monitoring only one secondary optical fiber sensor 32 that is vertically separated from the optical fiber sensor 31 in the extending direction of the dam body or the like is illustrated, but is not limited thereto, and scouring is performed. A configuration for starting monitoring of a plurality of secondary optical fiber sensors in the vicinity of the detected primary optical fiber sensor can also be employed. Thereby, even if scouring progresses rapidly over a wide area, the scouring range can be reliably grasped. In the third embodiment, the primary optical fiber sensor 31 and the secondary optical fiber sensor 32 having substantially the same length are made to correspond one-to-one in the direction perpendicular to the river bank 7 extending direction. The position of the secondary optical fiber sensor may be shifted with respect to the fiber sensor in the extending direction of the levee body. A plurality of shifted secondary optical fiber sensors may be arranged in correspondence.
[0055]
【The invention's effect】
According to the optical monitoring device of claim 1, the target monitoring target region in which the optical fiber sensor in which the optical fiber is connected to the optical fiber on the optical pulse tester side through the connection unit is set as the measurement target. It can be easily assembled just by installing it on the screen, and displacement, deformation, collapse, etc. of the target monitoring target area can be monitored efficiently. Since multiple optical fibers on the optical fiber sensor side can be connected to the optical fiber on the optical pulse tester side, displacement and deformation of the target monitored area can be achieved by installing multiple optical fiber sensors in the monitored area. , Monitoring the occurrence of collapse, etc. Since the optical fiber sensor can be obtained at a low cost and does not need to be installed outside the target monitoring target region, this monitoring device has an excellent effect of reducing the overall cost.
[0056]
According to the optical monitoring device of the second aspect, in particular, along the extending direction of the measurement target by the optical fiber sensor extending along the extending direction of the long measurement target such as a bank body. It is possible to efficiently grasp the occurrence of displacement, deformation, collapse, etc. in the monitoring area in the direction, and for example, from detection of abnormality such as deformation by a plurality of optical fiber sensors, occurrence of abnormality, such as displacement, deformation, collapse, etc. There is an excellent effect that the scouring width along the extending direction of the area, for example, the bank body, etc. can be efficiently grasped.
[0057]
According to the optical monitoring device of the third aspect, the optical fiber of the first optical fiber sensor extending along the extending direction of a long object to be measured such as a dam body is deformed (hereinafter referred to as “breaking” or “bending”). (Generally referred to as “disconnection”) from the position (hereinafter collectively referred to as “disconnection position”), an abnormality such as displacement, deformation, collapse, etc. has occurred in the target monitoring target area set on the embankment, etc. The width (for example, the scouring width along the river bank) can be grasped, and the depth (for example, the river) where an abnormality such as displacement, deformation, collapse, etc. has occurred in the monitored area from the disconnection position of the optical fiber of the second optical fiber sensor. The scouring depth of the embankment can be ascertained, so the area where the abnormality occurred in the monitored area can be efficiently and more directly compared to patrol from a place away from the place where the abnormality occurred. , Have an excellent effect of being able to grasp specifically .
According to a fourth aspect of the present invention, the disconnection of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber drawn from one end of the first optical fiber sensor. Then, the test light is incident from the optical pulse tester to the optical fiber of the second optical fiber sensor disposed corresponding to the first optical fiber sensor in which the disconnection of the optical fiber is detected. If the first optical fiber sensor detects an abnormality of the measurement target, the second optical fiber sensor can immediately start monitoring, and the size of the abnormality occurrence range can be quickly grasped. Excellent effect.
[0058]
According to the optical monitoring device of claim 5, detection of disconnection of an optical fiber drawn into an optical fiber sensor extended along an extending direction of a long object to be measured such as a bank body, and each optical fiber sensor The width of the abnormal part such as displacement, deformation, collapse, etc. that occurred in the monitoring target area by detecting the disconnection of the optical fiber between the pressure receiving bodies connected in series along the extending direction of the measurement target at The dimension along the extending direction (for example, the scouring width of the scouring range) can be grasped, and the optical fiber sensor connected to the direction perpendicular to the extending direction of the object to be measured detects the disconnection of the optical fiber. The depth of the abnormal part (for example, the scouring depth of the scouring range) can be grasped, and thereby the excellent effect that the scale of the whole range of the abnormal part can be easily grasped.
If the disconnection of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber drawn from one end of the optical fiber sensor as in claim 6, The optical pulse test is performed on an optical fiber drawn into another optical fiber sensor provided to be separated from the optical fiber sensor in a direction perpendicular to the extending direction of a long object to be measured such as the dam body. If the test light of the instrument is made incident, the optical fiber sensor detects the displacement, deformation, collapse, etc. of the object to be measured, and then separates it in the direction perpendicular to the extending direction of the object to be measured. Monitoring with another optical fiber sensor provided can be started quickly, and an excellent effect is obtained such that the depth of a range in which the measurement object is displaced, deformed, collapsed, etc. can be quickly grasped.
[Brief description of the drawings]
FIG. 1 is a plan view showing an entire optical monitoring apparatus according to a first embodiment of the present invention.
2 is a diagram showing break monitoring of a plurality of optical fibers in the optical monitoring apparatus of FIG. 1, wherein (a) shows a state in which four optical fibers are branched and connected to an optical pulse tester. Optical wiring diagram, (b) is a diagram showing a light intensity waveform showing the observation result of the return light of the incident light from the optical pulse tester of (a) to each optical fiber, and any optical fiber is broken. The figure which shows the state which has not arisen, (c) is a figure which shows the optical intensity waveform of the return light when a fracture | rupture arises in a part of optical fiber.
FIG. 3 is a plan view showing optical fiber disconnection monitoring before scour detection in the optical monitoring apparatus according to the second embodiment of the present invention.
4 is a plan view showing optical fiber disconnection monitoring after scouring detection in the optical monitoring device of FIG. 3; FIG.
FIG. 5 is a plan view showing optical fiber disconnection monitoring before scouring detection in the optical monitoring apparatus according to the third embodiment of the present invention.
6 is a plan view showing disconnection monitoring of an optical fiber after scouring detection in the optical monitoring device of FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical monitoring apparatus, 2 ... Optical pulse tester (OTDR), 3 ... Connection unit (optical termination box), 4 ... Optical fiber sensor, 4a, 4b ... Pressure receiving body, 7 ... Measurement object (river embankment, embankment) Body), 7a ... monitoring target area, 8 ... optical fiber, 9 ... optical fiber (optical cable), 20 ... light monitoring device, 21 ... first optical fiber sensor, 22 ... second optical fiber sensor, 8a, 8b ... optical fiber , 30 ... optical monitoring device, 31 ... optical fiber sensor (primary optical fiber sensor), 32 ... optical fiber sensor (secondary optical fiber sensor), 8c, 8d ... optical fiber, 81 to 84 ... optical fiber.

Claims (2)

An optical monitoring device that monitors various objects to be measured including light, such as riverbanks, coasts, river dikes (7), seawalls, and other artificial structures,
A plurality of first optical fiber sensors (21) extending substantially along the extending direction of the measurement object, and extending in a direction different from the extending direction of the measurement object, the first light Each second optical fiber sensor (22) provided at a position corresponding to the fiber sensor,
These optical fiber sensors are composed of a plurality of pressure receiving bodies (4a, 4b), and the first optical fiber sensor communicates with a plurality of pressure receiving bodies (4b) provided continuously in a target monitoring target area (7a). The optical fiber (8a, 8b) is configured to be broken or deformed by displacement between adjacent pressure receiving bodies,
In the second optical fiber sensor, the optical fiber (8) connected to the plurality of pressure receiving bodies (4a) connected to the monitoring target area is broken or deformed by the displacement between the adjacent pressure receiving bodies. Configured as
The optical fibers of the first and second optical fiber sensors are connected to the optical pulse tester so that the test light can enter, respectively.
If breakage or deformation of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber (8a) drawn from one end of the first optical fiber sensor, Test light is incident from the optical pulse tester to the optical fiber of the second optical fiber sensor disposed corresponding to the corresponding first optical fiber sensor in which the breakage or deformation of the fiber is detected. and optical monitoring device, characterized in that that (20). An optical monitoring device that monitors various objects to be measured including light, such as riverbanks, coasts, river dikes (7), seawalls, and other artificial structures,
Between the pressure receiving bodies adjacent to the optical fibers (8c, 8d) connected to a plurality of pressure receiving bodies (4b) arranged substantially continuously along the extending direction of the measurement target in the target monitoring target area (7a). The optical fiber sensors (31, 32) configured to be broken or deformed by the displacement of are disposed at a plurality of locations separated from each other in a direction perpendicular to the extending direction of the measurement object. The optical fiber of the fiber sensor is connected to the optical pulse tester (2) so that the test light can enter,
If breakage or deformation of the optical fiber is detected from the observation result of the return light of the incident light from the optical pulse tester to the optical fiber (8c) drawn from one end of the optical fiber sensor, the light The test light of the optical pulse tester is passed to an optical fiber (8c) drawn into another optical fiber sensor provided to be separated from the fiber sensor in a direction perpendicular to the extending direction of the measurement target. An optical monitoring device characterized by being incident .

Images