JP2016200416A - Scour Detection System - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scour detection system that is inexpensive and can accurately measure scour depth.SOLUTION: A system for detecting a scour state of ground P on which a bridge support B2 supporting a bridge body B1 is erected includes: a weight 25 placed on a ground surface P1 on which the bridge support B2 is erected; a rotatable drum 22 installed on the land part of the bridge support B2 or the bridge body B1; a wire 21 of which one end side is wounded around the drum 22 and at the other end side a weight is hung; a rotary encoder 24 for measuring the amount of rotation of the drum; optical fiber cables 16A-16D connected with the rotary encoder 24 and communicating measurement information; and optical transmission/reception devices 11A-11D connected with the optical fiber cables.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a system for detecting a scouring state of a river bottom where a bridge pier that supports a road passing over a river or the sea or a bridge main body of a railway or a bottom surface of the sea is provided.

  In order to detect the scouring condition of the ground, an optical or ultrasonic sensor that detects the condition of the riverbed from the air is known as a detection unit. As a result, light and ultrasonic waves are obstructed and an accurate distance cannot be detected.

  Therefore, for example, Patent Document 1 and Patent Document 2 propose a method in which a plurality of sensors are embedded in the riverbed (ground) and the riverbed is scoured and the sensors are directly exposed to the water flow. Sensors detect the presence or absence of scouring, but embed a plurality of sensors at positions spaced in the vertical direction, set the depth of each sensor in advance, and expose by scouring The depth of the scouring can be detected by the sensor.

  The sensor of Patent Document 1 is an AE (Acoustic Emission) sensor, and a sensor that is exposed by scouring the ground where a columnar sensor body to which a plurality of sensors are attached is erected is located in river water. Ultrasonic waves generated by the collision of floating solids or the like are detected, and this detection signal is amplified and transmitted by a conversion amplification unit provided in the sensor body. The conversion amplifier provided for each sensor body is driven by a power source.

  Further, the sensor in Patent Document 2 is formed of a swing sensor in which the switch is opened when the attitude of the sensor housing is changed during scouring, and a detection signal is generated by the operation of the switch. ing. This detection signal is generated by receiving power from a power source provided for each sensor.

JP 2001-108491 A JP-A-11-125524

  According to the devices of Patent Literature 1 and Patent Literature 2, the depth of scouring can be measured, but in order to measure the depth of scouring, it is necessary to install a plurality of sensors at intervals in the vertical direction. . Since the depth detection accuracy depends on the number of sensors, in order to increase the accuracy, it is necessary to reduce the interval and increase the number of sensors. As a result, the installation cost increases.

  In view of such circumstances, it is an object of the present invention to provide a scour detection system capable of measuring the scour depth accurately without using a plurality of sensors and reducing the cost.

  The scour detection system according to the present invention detects the scouring state of the ground on which the bridge support that supports the bridge body is erected.

  In such a scour detection system, in the present invention, a weight disposed on the ground surface on which the bridge support is erected, a rotatable drum installed on the land portion of the bridge support or the bridge body, and one end side is A wire wound around a drum and having a weight suspended from the other end, a rotary encoder that measures the amount of rotation of the drum, an optical fiber cable that is connected to the rotary encoder and communicates measurement information, and the optical fiber cable And an optical transmission / reception device connected to each other. There is no limitation on the form of the weight itself as long as the weight is suspended by a wire, so long as the ground is scoured, the weight settles down.

  In the present invention having such a configuration, since the weight is disposed on the ground surface, for example, on the river bottom, the weight sinks by the scouring depth of the ground. A weight is suspended from the wire, and the wire is wound around the drum as the weight settles. The amount of rotation of the drum is measured by a rotary encoder connected to the drum, the wire feed amount is calculated from the drum rotation amount and the wire winding diameter, and the scouring depth is measured. Only one rotary encoder is required as a sensor.

  In the present invention, the rotary encoder includes a rotating body in which a magnet body is attached to one or a plurality of positions on the outer peripheral portion, and a magnetic field fluctuation detection unit that detects a magnetic field fluctuation accompanying movement of the magnet body in the circumferential direction of the rotating body. The magnetic field fluctuation detection unit can be a Faraday element sensor that changes the intensity of light output by the fluctuation of the magnetic field.

  This rotary encoder is composed of a rotator and a magnetic field fluctuation detector for detecting the rotation state of the rotator. A magnet body is disposed on the outer peripheral portion of the rotating body, and a magnetic field fluctuation detecting unit for detecting a magnetic field fluctuation is provided in the vicinity of the rotating body. By moving in the circumferential direction, the Faraday element sensor detects a change in the magnetic field in the vicinity of the magnetic field change detection unit, and measures the amount of rotation of the rotating body.

  The Faraday element sensor detects the passage of the magnet body and counts the number of passes by detecting the passage of the magnet body because the light intensity output from the Faraday element sensor varies when the magnetic body changes due to the proximity of the magnet body. The amount of rotation can be measured.

  Since the Faraday element sensor is only connected to an optical fiber cable, it does not use electrical components, does not require a power source (facility), and is not susceptible to lightning strikes such as lightning strikes. Thus, since a power supply (equipment) is not required for the Faraday element sensor, it is possible to reduce the initial cost of construction and the running cost of application.

  In addition, since the Faraday element sensor and the optical fiber cable are merely optically connected, there are no mechanical parts, so the possibility of failure is low even after long-term use, and the stability is high.

  In addition, since measurement signals are optically communicated with optical fiber cables, it is possible to install base stations where transceivers, control devices, analyzers, etc. are installed at remote locations several kilometers to tens of kilometers away from the bridge. Thus, the degree of freedom of operation of the detection system is improved.

  In the present invention, the winding start end of the wire wound around the drum can be prevented from being fixed to the drum.

  In such a form, since the winding start end of the wire is wound around the drum and is not fixed, the wire is separated from the drum when it is drawn out over its entire length. If the winding start end of the wire is fixed to the drum, not only will the weight sink due to scouring due to a typhoon or flood, but if the weight is swept away by water, the wire will be fed out of the drum. Thus, the drum may be pulled by the wire and damaged. However, by not fixing the winding start end of the wire to the drum as in the present invention, it is possible to prevent the drum from being damaged because the wire only comes out of the drum even if the weight is flowed.

  Moreover, since it is only necessary to wind the wire around the drum when it is restored, there is no need to re-install the drum, and the cost can be reduced and the restoration time can be shortened.

  In the present invention, it is preferable that the wire is passed through a protective tube provided along the bridge support in at least a part of the range from the drum to the weight.

  In this way, the wire is protected without being exposed to the outside, so it may be swept away by vibrations such as an increase in the flow rate of turbid flow, contact with floating objects such as driftwood, or damage to the wire. Can be prevented.

  In the present invention, as described above, the wire is fed out from the drum due to the sedimentation of the weight accompanying the scouring of the ground, and the scouring depth is measured by obtaining this feeding amount from the rotation amount of the drum measured by the rotary encoder. When scouring occurs in the ground, the weight placed on the ground surface, for example, the bottom of the river, sinks by the scouring depth, and the wire wound around the drum as the weight sinks The amount of rotation of the drum is measured by a rotary encoder connected to the drum, the amount of wire feed is calculated from the amount of drum rotation and the wire winding diameter, and the scouring depth is measured. It is economically advantageous to provide only one encoder, and the scouring depth can be measured continuously and the scouring depth can be accurately known.

1 is a schematic configuration diagram mainly showing a ground scour monitoring device in a scour detection system as an embodiment of the present invention. It is a schematic block diagram which shows the part located in a bridge among the scour detection systems of FIG. The internal structure of the detection box part seen by FIG. 2 is shown, (A) is a front view, (B) is a side view.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of the apparatus of the present embodiment as a scour detection system, and FIG. 2 is a diagram showing a detection portion on the distal end side of the optical fiber cable of each detection unit of FIG.

  As shown in FIG. 1, the present embodiment has a ground scour monitoring device 10 as a monitoring base station installed in a station building, a security zone, etc., and the ground scour monitoring device 10 transmits light. Then, the scouring depth is obtained from a large number of detection units 11 (only four detection units 11A, 11B, 11C, and 11D are shown in FIG. 1) as optical transmission / reception devices to be received and signal information from each detection unit. It has the depth conversion apparatus 12, the control apparatus 13 which determines the output from the depth conversion apparatus 12 while controlling these, and the display apparatus 14 which displays the result. The control device 13 is connected to a wireless communication device 15 that communicates with the train T or the like.

  Optical fiber cables 16A, 16B, 16C, and 16D extend from each of the detection units 11A, 11B, 11C, and 11D, and these optical fiber cables 16A, 16B, 16C, and 16D have one trunk cable as a preferred form. 17 are extended to the position of a bridge such as a river where ground scouring should be detected, and their tips are connected to Faraday proximity sensors 18A, 18B, 18C, 18D using Faraday elements. As described above, since a large number of the detection units 11 are provided, the corresponding number of optical fiber cables 16 are inserted into one trunk cable 17.

  As shown in FIG. 1, one trunk cable 17 extends from the position of a bridge B such as a railway to a plurality of bridge supports B <b> 2 that support the bridge B as shown in FIG. 2. The optical fiber cables 16A and 16B are sequentially drawn out from the trunk cable 17. In FIG. 2, Faraday proximity sensors 18A and 18B to which tips of optical fiber cables 16A and 16B drawn from the main cable 17 are connected are shown. Further, instead of inserting a plurality of optical fiber cables 16 into the main cable 17, for example, an optical fiber in which a plurality of optical fibers are accommodated in the main cable 17 and the optical fibers are inserted into a metal tube. The cable 16 may be branched from the trunk cable 17 to each bridge support B2.

  As shown in FIG. 2, the bridge B has a bridge body B1 located above the river, and a bridge support B2 that stands on the ground of the river and forms a column supporting the bridge body B1 at the upper end. The detection box 20 is supported at the corner formed by both the bridge body B1 and the bridge support B2. The detection box 20 can be supported by either the bridge body B1 or the bridge support B2.

  As described above, the ends of the optical fiber cables 16A, 16B, 16C, and 16D extending from the detection units 11A, 11B, 11C, and 11D are connected to the Faraday proximity sensors 18A, 18B, 18C, and 18D. Although the fiber cables 16A, 16B, 16C, and 16D extend to the corresponding bridge support B2 of the bridge B, only two optical fiber cables 16A and 16B are illustrated in FIG. Since the detection boxes 20 into which the ends of the two optical fiber cables 16A and 16B are introduced have the same internal configuration, the detection box 20 into which the optical fiber cable 16A is introduced will be described below.

  Inside the detection box 20, a drum 22 around which a wire 21 rotatably supported is wound, a rotating body 23 that rotates together with the drum 22, and a tip of the optical fiber cable 16 </ b> A connected to the rotating body 23. A displacement meter composed of the Faraday proximity sensor 18A serving as a magnetic field fluctuation detection unit arranged close to the outer periphery is accommodated. The rotary body 23 and the Faraday proximity sensor 18A form a rotary encoder 24. A wire 21 is wound around the drum 22. One end of the wire 21 is not fixed to the drum 22, and the other end extends from the drum 22 to the outside of the detection box 20 and hangs down. Is attached. The weight 25 is located on the upper surface (ground surface) P1 of the ground P serving as the riverbed. The weight 25 is merely located on the ground surface P1, and is not embedded in the ground. The shape and material of the weight 25 may be set as appropriate depending on the assumed flow rate of the river. For example, if the shape of the tetrapot is set on a river or a coast, it is stable on the ground at the bottom of the river in a normal state. This is preferable. The material can be concrete or steel, for example.

  A protective tube 26 is provided from the detection box 20 so as to hang down below the surface of the river, and the wire 21 is inserted into the protective tube 26 in a free state. The lower end of the wire 21 is the other end. Emerges from the protective tube 26. Thus, in this way, the wire 21 is protected without being exposed to the outside. The wire 21 is protected by an increase in the flow rate of turbidity or the like, contact with floating objects such as driftwood, vibration, or injury. There is nothing to do.

  As shown in FIGS. 3A and 3B, the drum 22 has a body portion 27, flange portions 28A and 28B, and shaft portions 29A and 29B. The bearing housing is installed in the detection box 20. The bearings 31A and 31B housed in the portions 30A and 30B are rotatably supported. Shaft portions 29A and 29B protruding from flange portions 28A and 28B provided at both ends of the drum 22 are supported by corresponding bearings 31A and 31B, respectively.

  In the drum 22, the wire 21 is wound around the body portion 27, and as described above, one end serving as a winding start end is not fixed to the drum 22, and the other end is suspended from the drum 22. It is suspended through a window portion 20A formed on the wall, and is inserted through a protective tube 26 that is suspended from the bottom wall.

  One shaft portion 29B of the drum 22 protrudes from the corresponding bearing 31B, and the rotating body 23 of the rotary encoder 24 is attached to the tip thereof so that the rotating body 23 rotates integrally with the shaft portion 29B. It has become.

  The rotating body 23 is formed in a polygon (an octagon in the illustrated example), its outer peripheral surface is a polyhedron, and a magnet body 23A is attached to each surface.

  A Faraday proximity sensor 18 </ b> A of the rotary encoder 24 is disposed immediately below the rotating body 23 and is supported by a support body 32 attached to the bottom wall of the detection box 20. . An optical fiber cable 16A extends out of the detection box 20 from the Faraday proximity sensor 18A. Since the optical fiber 16A is connected to the rotary encoder 24, the supervisory base station where the optical transceiver is installed can be installed at a position several kilometers to several tens of kilometers away from the bridge support. Even if the place to be used is in a mountainous area or a remote area, it is possible to install a supervisory base in a place where it is easy to install an optical transceiver at a place away from the bridge, and the situation of scouring the bridge support from a remote place Can be confirmed. In addition, since the Faraday proximity sensor and the optical fiber are only connected in the detection box 20, no electrical components are used, and there is no possibility of being affected by lightning strikes such as lightning strikes. Furthermore, since the Faraday proximity sensor and the optical fiber are merely optically connected, there are no mechanical parts, so that even if they are used for a long period of time, the possibility of failure is low and stability is high.

  In the apparatus of this embodiment configured as described above, when the ground P is scoured at the base position of the bridge support B2 of the bridge B due to the increase of rivers, as shown by a two-dot chain line in FIG. Since P is locally sunk, the weight 25 located on the ground surface P1 is lowered by the scouring depth by its own weight. That is, the wire 21 is fed by the amount of the lowering of the weight 25, and the drum 22 is rotated accordingly. As the drum 22 rotates, the rotating body 23 attached to the shaft portion 29 </ b> B of the drum 22 also rotates by the same amount as the drum 22. Due to the rotation of the rotating body 23, the plurality of magnet bodies 23 </ b> A attached to the outer peripheral surface of the rotating body 23 are arranged in front of the Faraday proximity sensor 18 </ b> A disposed immediately below the rotating body 23 and in proximity to the outer peripheral surface of the rotating body 23. Pass one after another. Therefore, the strength of the magnetic field at the position where the Faraday proximity sensor 18A is placed varies with the passage of the magnet body 23A.

  The Faraday proximity sensor 18A has a Faraday element. The Faraday element has a characteristic of changing the intensity of reflected light by rotating the plane of polarization of linearly polarized light according to the strength of the magnetic field. The used Faraday proximity sensor 18A detects the change in the light intensity of the output light due to the change in the magnetic field when the magnet body 23A approaches.

  Thus, when the light transmitted from the detection unit 11A is reflected and output by the Faraday proximity sensor 18A, it is output as a measurement information signal in which the light intensity of the output light changes every time the magnet body 23A approaches, and the detection unit 11A receives this, knows the number of passes of the magnet body 23A from the number of changes in the light intensity, and obtains the number of rotations of the drum 22 from this. A signal indicating the number of rotations is sent to the depth conversion device 12. The depth conversion device 12 can measure the scouring depth by converting the number of rotations from the diameter of the drum 22 and the winding diameter of the wire 21 to the feeding length of the wire 21. Further, a signal indicating the scouring depth is sent to the control device 13. Then, when the control device 13 compares the calculated scouring depth with an allowable value indicating a preset danger depth and determines that the risk exceeds the allowable value and is in a dangerous state, the display device 14 displays the determination result. indicate. Moreover, the radio | wireless communication apparatus 15 can transmit the radio signal corresponding to the said determination result toward the train T or a security area, and can notify the crew member of this train T. As a result, accidents can be prevented by stopping the train T as appropriate.

  In the present embodiment, since the winding start end of the wire 21 is not fixed to the drum 22, not only does the weight 25 sink due to scouring due to a typhoon or flood, but when the weight 25 is flowed, the wire 21 is moved to the drum 22. Since the wire 21 is pulled out from the drum 22 after being fully fed out from the drum, there is no possibility that the drum is pulled by the wire and damaged. Thus, the drum is prevented from being damaged.

  Moreover, since it is only necessary to rewind the wire 21 around the drum 22 at the time of restoration, it is not necessary to install the drum 22 again.

  In the present embodiment, an example in which a plurality of detection units are provided corresponding to each of the optical fiber cables reaching the detection boxes of a plurality of bridge supports has been illustrated, but each of the optical fiber cables is not provided with a plurality of detection units. Alternatively, only one common detection unit may be provided, and the common detection unit may be sequentially switched and connected to each optical fiber cable. In this way, the cost can be greatly reduced with respect to providing the detection unit.

11A to 11D Optical transceiver (detection unit)
16A-16D optical fiber cable 18A-18D Faraday element sensor (Faraday proximity sensor)
21 Wire 22 Drum 23 Rotating body 23A Magnet body 24 Rotary encoder 25 Weight 26 Protective tube B Bridge B1 Bridge body B2 Bridge support P Ground P1 Ground surface

Claims (4)

In the system that detects the scouring condition of the ground where the bridge support that supports the bridge body is erected,
A weight placed on the ground surface on which the bridge support is erected,
A rotatable drum installed on the land part of the bridge support or the bridge body,
A wire having one end wound around a drum and a weight suspended from the other end;
A rotary encoder that measures the amount of drum rotation;
An optical fiber cable connected to a rotary encoder to communicate measurement information;
An optical transceiver connected to the optical fiber cable;
A scour detection system characterized by comprising: The rotary encoder includes a rotating body having a magnet body attached at one or a plurality of positions on the outer peripheral portion, and a magnetic field fluctuation detection unit that detects a magnetic field fluctuation accompanying movement of the magnet body in the circumferential direction of the rotating body. ,
The scouring detection system according to claim 1, wherein the magnetic field fluctuation detection unit is a Faraday element sensor in which the intensity of light output changes due to the fluctuation of the magnetic field.   The scour detection system according to claim 1 or 2, wherein a winding start end of the wire wound around the drum is not fixed to the drum.   4. The scouring according to claim 1, wherein the wire is passed through a protective pipe provided along the bridge support in at least a part of the range from the drum to the weight. Detection system.

Images