JP2011012516A - Device and system for detecting outflow of scouring-protection block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect an outflow of a scouring protection block surrounding a bridge pier with high accuracy.SOLUTION: A detection device 15 is buried in part of a scouring protection block 13 which surrounds the bottom of the bridge pier 12. The detection device 15 detects a degree and the direction of the inclination and vibration of the scouring protection block 13. When it is determined that the block is abnormal from the detection result, the detection device 15 transmits a low frequency electromagnetic wave. A receiver 16 is provided for receiving the low frequency electromagnetic wave transmitted from the detection device 15, and the receiver 16 is connected to a monitoring server 18 by a radio network 17. By detecting acceleration data of the three-axis acceleration sensor of the detection device, the degree of the inclination, the direction of the inclination, and the vibration are determined. Since determination on an the abnormal state is made based on the total of these items, the accuracy of the determination on the abnormality is improved, and the outflow of the scouring protection block 13 can be detected in advance.

Description

  The present invention relates to a scour protection block flow detection device and a scour protection block flow detection system that detect the flow of a plurality of scour protection blocks installed around a pier.

  The scouring protection works around the piers of railway bridges prevent the scouring of the riverbed by mainly laying heavy objects around the piers. Heavy objects laid around the pier are concrete blocks, called scour protection blocks. The scour protection block controls river bed changes and scouring around the piers, but at the end of the laying range, it may be deformed from the original state due to the riverbed deterioration and scouring effects. Such deformation leads to a decrease in the protective function and may reduce the stability of the pier foundation at the time of water increase. In addition, when water increases, the deformation progresses rapidly and the scour protection block may be washed away. Therefore, detecting the deformation of the scour protection block is important for monitoring the soundness of the bridge foundation.

When the watcher regularly monitors the condition of the scour protection block, it is extremely difficult to visually check the condition of the scour protection block under the water surface due to reflection of light on the river surface or turbidity of rain water. Have difficulty. On the other hand, detecting the deformation of the scour protection block as soon as possible is important for the safety of the bridge.
Therefore, in order to detect the deformation of the scour protection block, it is conceivable to attach a detection device to the scour protection block.
However, in the disaster monitoring equipment for structures such as scouring protection blocks installed on the riverbed, the cable type can be broken or damaged due to deformation or minute movement of spillage or scouring protection blocks. There is sex. Therefore, it is required to use a wireless disaster monitoring facility for structures installed on the riverbed. However, in a general wireless disaster monitoring facility, radio waves may be attenuated due to river water or earth and sand in the transmission path, and communication may become impossible, and the function may not be satisfied.

  Therefore, disaster monitoring equipment has been proposed that uses low-frequency electromagnetic waves for signal exchange and avoids natural environment constraints such as rivers and earth and sand. For example, in Patent Document 1, the output of a tilt sensor that detects a tilt state is used as a trigger to send a low-frequency magnetic field, and the low-frequency magnetic field sent by the monitor sensor is received to detect the change or collapse of the slope. In a system composed of a reception processing device that generates an alarm, a monitoring sensor has a built-in timer and periodically sends a low-frequency magnetic field, and the low-frequency magnetic field to be sent is modulated with ID information unique to each monitoring sensor. A function is provided, and the reception processing device demodulates the low-frequency magnetic field to identify the ID information, and determines whether or not the low-frequency magnetic field is periodically transmitted from each monitoring sensor. An earth and sand disaster monitoring device for grasping the soundness of a coil is disclosed.

JP 2007-262851 A

  The earth and sand disaster monitoring device disclosed in Patent Document 1 mainly employs a method of detecting the deformation of the structure by inclination, but in the case of a scour protection block, a healthy posture change due to river bed changes and the risk of loss There is a change in posture, and it is not possible to judge the runoff by the inclination angle of the scour protection block uniquely.

  Moreover, although the above-mentioned earth and sand disaster monitoring apparatus can detect that the deformation | transformation accompanying the inclination occurred in the scour protection block, it cannot detect such a deformation sign in advance.

  In particular, when monitoring a bridge in a railway, it is necessary to stop the operation of the railway when it is determined that the stability of the bridge is impaired, and monitoring reliability is required. In the above-mentioned earth and sand disaster monitoring device, there is a possibility that the deformation is erroneously detected due to vibration caused by the falling material colliding with the scour protection block.

  In view of the above-described problems, the present invention provides a scour protection block run-off detection device and a scour protection block run-off detection system capable of accurately and easily detecting run-off of a plurality of scour protection blocks installed around a pier. The purpose is to provide.

  In order to solve the above-mentioned problem, the scouring protection block loss detection device of the present invention is provided in each of a plurality of scouring protection blocks installed around the pier, and determines whether or not there is an abnormality in the scouring protection block. A scour protection block loss detection device, wherein the acceleration detection device is detected by an acceleration detection device that detects three-axis acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction, and the three-axis acceleration detection means. And a control device that determines the presence or absence of an abnormality of the scouring protection block using the magnitude of the inclination, the direction of the inclination, and the vibration obtained from the three-axis acceleration data. It is.

  The scouring protection block loss detection device of the present invention is characterized in that, in the above invention, the scouring protection block loss detection device further includes a transmitter that transmits its own identification information and abnormality information by a low frequency electromagnetic wave having a frequency of 1 kHz to 10 kHz.

  The scouring protection block loss detection device of the present invention is provided in a part of the scouring protection block.

  The scouring protection block loss detection device of the present invention is characterized in that the control device determines that an abnormality has occurred when it detects a slope that has continued for a predetermined time.

  The scouring protection block loss detection device of the present invention is characterized in that the control device determines that an abnormality is detected when vibration of the protection block is detected.

  The scour protection block run-off detection system of the present invention is a scour protection block run-off detection system for detecting run-off of a plurality of scour protection blocks installed around a pier, and a plurality of scours installed around a pier. A scour protection block run-off detection device embedded in a protection block for detecting the run-off of the scour protection block, a transmitting device and a receiving device for transmitting a signal from the scour protection block run-off detection device with low-frequency electromagnetic waves, Analyzing means for analyzing data from the scouring protection block loss detection device, the scouring protection block loss detection device comprising: an acceleration detection device for detecting acceleration applied to the embedded scouring protection block; and each acceleration A control device for determining the presence or absence of abnormality of the scouring protection block from the acceleration data detected by the detection device, the control device , And judging the presence or absence of abnormality from the acceleration data obtained from the acceleration detecting device.

  The scouring protection block loss detection system of the present invention is characterized in that the analysis means analyzes the number and position of the scouring protection blocks determined that the abnormality has occurred, and determines the risk of the pier. To do.

  According to the present invention, a sound posture change of a scouring protection block and a posture change at risk of being washed away can be identified to determine an alarm, and reliability is improved. In addition, according to the present invention, it is possible to detect a prior sign that the scouring protection block vibrates before being washed away, and it is possible to implement a prior measure. Further, according to the present invention, it is possible to evaluate the behavior of a plurality of scouring protection blocks in combination with information such as a rise in river water level, and to perform accurate determination.

It is explanatory drawing of the bridge which can apply the 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the scouring protection block loss detection system of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the detection apparatus in the scouring protection block loss detection system of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the structure of the receiver in the scouring protection block loss detection system of the 1st Embodiment of this invention. It is explanatory drawing of the relationship between the loss of a scour protection block, and its movement. It is explanatory drawing which shows the structure of the scouring protection block loss detection system of the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a railway bridge to which the first embodiment of the present invention can be applied. In FIG. 1, a bridge 11 is for a railway bridged over both banks of a river 10, and both ends thereof are supported on opposite banks of the river 10, and an intermediate portion thereof is a bridge pier planted from the riverbed of the river 10. 12 is supported.

  As shown in FIG. 2, a plurality of concrete scour protection blocks 13 are laid around the bottom floor of the pier 12. The scour protection block 13 prevents the river bed from being scoured by the water flowing through the river 10. In order to detect the loss of the scouring protection block 13, in the first embodiment of the present invention, a detection device 15 is embedded in a part of the plurality of scouring protection blocks 13.

  The detection device 15 may be embedded in all of the scouring protection blocks 13 or may be embedded only in a part of the scouring protection blocks 13 as shown in FIG. For example, the detection device 15 may be embedded only in the scouring protection block 13 near the pier 12, or the detection device 15 may be embedded in the scouring protection block 13 at predetermined intervals. In addition, as for the arrangement of the scour protection block 13 in which the detection device 15 is embedded, various arrangement patterns can be considered corresponding to the size and shape of the pier 12 and the shape of the riverbed. For example, the arrangement density of the scouring protection block 13 in which the detection device 15 is embedded in the region where the unevenness exists in the river bed is set higher than the arrangement density of the scouring protection block 13 in which the detection device 15 is embedded in the other region. . Further, when the water is increased, the arrangement density of the scour protection blocks 13 in which the detection devices 15 are embedded in the area of the riverbed around the pier where the water pressure is most applied by the river flow is detected in other regions. 15 is made higher than the arrangement density of the scour protection blocks 13 embedded therein. Moreover, like the checkerboard pattern of a chess board, it arrange | positions alternately so that the edge | side of the scour protection block 13 in which the detection apparatus 15 was embed | buried may not adjoin another. In the arrangement pattern described above, it is possible to detect whether or not the scouring protection block embedded in any of the detection devices has been washed away by the ID signal of each detection device.

  The detection device 15 senses the magnitude of the inclination of the scour protection block 13, the direction of the inclination (direction of inclination obtained from the X axis, Y axis, and Z axis), and vibration, and determines from these detection results that there is an abnormality. In this case, for example, a low frequency electromagnetic wave (referred to as a low frequency magnetic field) of 1 kHz to 10 kHz is transmitted. As shown in FIG. 2, the bridge pier 12 is provided with a receiving device 16 for receiving low-frequency electromagnetic waves from the detection device 15. A low frequency electromagnetic wave of 1 kHz to 10 kHz has a very low rate of energy absorption by the ground, and reflection at the boundary with water or the ground is difficult to occur. For this reason, communication is possible even in the riverbed or on the ground. The receiving device 16 communicates with the monitoring server 18 via the wireless network 17.

  Although the receiving device 16 is installed on the bridge pier 12 here, the receiving device 16 can be placed anywhere as long as it is within the reach of the low-frequency electromagnetic wave from the detecting device 15 (for example, 30 m). good. In addition, it is desirable that the receiving device 16 be installed in a place that is not affected by the flood. Further, a pole may be set up in the river 10 and the receiving device 16 may be installed there. A plurality of receiving devices 16 may be provided.

  FIG. 3 shows an example of the internal configuration of the detection device 15. As shown in FIG. 3, the detection device 15 includes a triaxial acceleration sensor 21, a control unit 23, an ID generation unit 24, a transmission unit 25, a timer 26, and a transmission antenna 27.

  The triaxial acceleration sensor 21 detects acceleration in the triaxial directions of the X axis, the Y axis, and the Z axis. A detection signal (acceleration data) of acceleration of each of the X axis, Y axis, and Z axis from the triaxial acceleration sensor 21 is sent to the control unit 23.

  The control unit 23 determines the magnitude of the inclination, the direction of the inclination, and the vibration from the detection signal of the acceleration (including gravitational acceleration) applied to each of the X axis, the Y axis, and the Z axis from the triaxial acceleration sensor 21. Detect and determine whether there is an abnormality. That is, since the detection signal from the triaxial acceleration sensor 21 is an acceleration detection signal, the detection signal from the triaxial acceleration sensor 21 is detected with a period shorter than the period of vibration, and the acceleration data (for example, voltage waveform) is obtained. It is possible to detect a change in the inclination from the initial state where the scouring protection block is arranged by integrating the acceleration data with a long period by determining whether the vibration is generated by detecting the amplitude as it is. Moreover, the control part 23 can detect the inclination at that time only by gravity acceleration, when vibration is not detected. The inclination of the scour protection block described above is determined by the control unit 23 from the magnitudes of the inclinations of the X axis, the Y axis, and the Z axis.

  Here, when the train passes through the bridge, the vibration of the bridge itself also vibrates through the pier, and the vibration caused by the passage of the train is not the same as the case where the scour protection block vibrates due to the water pressure due to the increase in river water. It is necessary to prevent detection. In general, since the vibration caused by the train has a higher frequency than the vibration caused by the water increase, the vibration may be detected by a period in which the frequency of the vibration caused by the train is not detected. In this way, malfunctions due to train vibration can be suppressed by detecting acceleration data from the acceleration sensor with a time constant longer than the train vibration period.

  When receiving the transmission activation signal from the control unit 23, the transmission unit 25 oscillates a low frequency signal of 1 kHz to 10 kHz. Further, when receiving the timer signal from the timer 26, the transmission unit 25 oscillates a low frequency signal. In addition, a device-specific ID (identification) signal is sent from the ID generation unit 24 to the transmission unit 25. At other times, the operation of the transmission unit 25 is stopped, and consumption of the battery (power supply unit 30) is suppressed.

The oscillation signal from the transmission unit 25 is modulated by the ID signal from the ID generation unit 24 and transmitted from the transmission antenna 27. The transmission antenna 27 is a coil, for example. That is, when a coil is used as the transmission antenna 27, when an oscillation signal from the transmission unit 25 is supplied, a magnetic field that varies with time is generated in the coil, and a low-frequency electromagnetic wave of 1 kHz to 10 kHz is generated from the transmission antenna 27. Is generated.
The power supply unit 30 is a battery, for example, and supplies driving power to each unit in the detection unit 15.

  When modulating the transmission signal with the ID signal, amplitude modulation may be used, or a signal having a frequency component corresponding to the ID signal may be generated.

  FIG. 4 shows the configuration of the receiving device 16. As illustrated in FIG. 4, the reception device 16 includes a reception antenna 31, a reception processing unit 32, an ID detection unit 33, a wireless interface unit 34, and a wireless communication antenna 35.

  The receiving antenna 31 receives low-frequency electromagnetic waves from the detection device 15, and a coil is used as the receiving antenna 31. A reception signal of the reception antenna 31 is sent to the reception processing unit 32. The output signal of the reception processing unit 32 is sent to the ID detection unit 33. The received signal is demodulated by the ID detector 33 and an ID signal is detected. The ID signal detected by the ID detection unit 33 is sent to the wireless interface unit 34.

  The wireless interface unit 34 is an interface for connecting to the wireless network 17 (see FIG. 2). The wireless communication antenna 35 is an antenna for transmitting and receiving data via the wireless network 17. The wireless network 17 is a mobile phone network, a wireless LAN, a mobile high-speed communication network, or the like. The ID signal detected by the ID detection unit 33 is sent to the monitoring server 18 via the wireless network 17 by the wireless interface unit 34.

  Next, an outline of the operation of the system of the present invention will be described. As shown in FIG. 2, a scour protection block 13 in which a detection device 15 is embedded is laid around the bottom of the pier 12. As shown in FIG. 3, the detection device 15 is provided with a triaxial acceleration sensor 21.

  In order to check the operation, a low frequency electromagnetic wave obtained by modulating a unique ID signal of each device is transmitted from the detection device 15 at a predetermined cycle (for example, once a day). That is, the timer 26 of the detection device 15 shown in FIG. 3 transmits low frequency electromagnetic waves obtained by modulating the unique ID signal of each device from the detection device 15 at a predetermined cycle. This low frequency electromagnetic wave is received by the receiving device 16, and the received ID signal is sent to the monitoring server 18 via the wireless network 17.

  When the scouring protection block 13 is lost due to the water flow flowing through the river 10 at the time of water increase such as a typhoon, the scouring protection block 13 moves and the inclination of the scouring protection block 13 changes. Further, if the risk of the scouring protection block 13 being washed away increases, the scouring protection block 13 causes a specific vibration as a sign.

  When the scour protection block 13 is tilted or vibration is generated, the tilt or vibration is detected by the three-axis acceleration sensor 21 of the detection device 15 shown in FIG. 3, and this detection signal is sent to the control unit 23. . The control unit 23 determines whether there is an abnormality from the magnitude of the inclination, the direction of the inclination, and the vibration, and in response to this, a transmission activation signal is output from the control unit 23 to the transmission unit 25. That is, when the difference between the inclination at the time of placement and the current inclination exceeds the preset inclination threshold value and the difference in the inclination direction exceeds the preset direction threshold value, the control unit 23 scours the protection block 13. If the vibration amplitude exceeds a preset amplitude threshold value, it is determined that there is a risk of loss. As a result, when abnormalities such as vibration and loss of the scour protection block 13 occur, the detection device 15 transmits a low-frequency electromagnetic wave obtained by modulating a unique ID signal of each device. Here, the control unit 23 transmits abnormality information corresponding to each abnormality of vibration or inclination via the transmission unit 25.

This low frequency electromagnetic wave is received by the receiving device 16, and the received ID signal is sent to the monitoring server 18 via the wireless network 17. When the monitoring server 18 analyzes the data from the receiving device 16 and determines that there is a danger, an alarm is output.
At this time, when the monitoring server 18 is washed away, the correspondence between the level of the dangerous state of the pier and the arrangement position of the scouring protection block 13 is preset in the inside, and the scouring protection block 13 that has been washed away is set. It may be configured to detect the arrangement position of and to output a warning at a level corresponding to the arrangement position. Here, since the scour protection blocks 13 arranged at the above-mentioned arrangement positions are associated with ID signals that are uniquely set to the scour protection blocks 13, monitoring is performed using an ID signal that is transmitted together with a signal that notifies abnormality. The server 18 can determine whether an abnormality has occurred in the scour protection block at any position.
In addition, the monitoring server 18 has a preset correspondence between the level of a dangerous state when it is flushed and the number of scouring protection blocks 13 that are flushed. May be configured to output an alarm at a level corresponding to the number of detected signals.
Further, a level of a dangerous state is set for the scour protection block 13 vibration as well as in the case of the loss.

  As described above, in the first embodiment of the present invention, the scour protection block 13 in which the detection device 15 is embedded is laid around the bottom of the pier 12, and the magnitude of the inclination, the direction of the inclination, and the vibration By detecting this, it can be determined that the scouring protection block 13 has a high risk of loss or loss, and an alarm can be output.

  FIG. 5 illustrates the movement of the scour protection block. In FIG. 5, the scour protection blocks 13a and 13b are scour protection blocks that are abnormal or have been washed away when the typhoon or other water is increased. The scour protection blocks 13c to 13e are scour protection blocks that have moved in a natural state. Further, the scour protection block 13f is a scour protection block in which vibration is generated when the risk of loss is high.

  Thus, the position and angle of the scour protection block 13 change not only when the water increases but also in a natural state. Therefore, if it is simply determined that the scouring protection block 13 is washed away only by the magnitude of the inclination, a false detection occurs.

  Therefore, as shown in FIG. 3, in the detection device 15 according to the first embodiment of the present invention, the triaxial acceleration sensor 21 detects accelerations in the X axis direction, the Y axis direction, and the Z axis direction. The control unit 23 determines the magnitude of the inclination, the direction of the inclination, and the vibration. Thus, in FIG. 5, the movement at the time of run-off indicated by the scouring protection blocks 13a and 13b and the movement in the natural state indicated by the scouring protection blocks 13c to 13e are determined from the direction of the inclination and the magnitude of the inclination. This makes it possible to prevent erroneous detection.

  Further, as shown by the scouring protection block 13f, the scouring protection block 13 may generate a specific vibration before the loss occurs. In the detection device 15 according to the first embodiment of the present invention, the control unit 23 can detect this specific vibration from the output of the triaxial acceleration sensor 21. For this reason, in the detection apparatus 15 of the first embodiment of the present invention, it is possible to detect in advance that the scouring protection block 13 has been lost. As described above, the control unit 23 determines the magnitude of the inclination, the direction of the inclination, and the vibration based on the detection output of the three-axis acceleration sensor 21, and determines the abnormality by combining these to determine the abnormality. The accuracy is improved, and the scouring protection block 13 can be detected in advance.

  That is, the control unit 23 can determine that an abnormality has occurred when a tilt that has continued for a predetermined time is detected from the detection output of the triaxial acceleration sensor 21. Moreover, the control part 23 can determine with it being abnormal, when the vibration of the scour protection block 13 is detected from the detection output of the triaxial acceleration sensor 21. Moreover, the control part 23 can determine with it being abnormal, when the vibration or inclination of the scouring protection block 13 of a predetermined position is detected.

  In the detection device 15 according to the first embodiment of the present invention, as shown in FIG. 2, the detection device 15 is embedded in the plurality of scour protection blocks 13 around the bottom of the pier 12. The low frequency electromagnetic wave transmitted from each detection device 15 includes a unique ID signal. For this reason, the monitoring server 18 can determine at which position the scouring protection block 13 is washed away. Thereby, the risk of the bridge pier 12 can be determined by analysis from the number and positions of the scour protection blocks 13 that have been washed away. For example, if the number of scour protection blocks 13 that have been washed away exceeds a predetermined number, it can be determined that the risk of supporting the pier 12 is high. Further, when the scouring protection block 13 located away from the pier 12 is washed away, there is little risk of supporting the pier 12 and when the scouring protection block 13 located near the pier 12 is washed away. It can be determined that the risk of supporting the pier 12 is high.

  Next, a second embodiment of the present invention will be described. FIG. 6 shows a configuration of a detection apparatus according to the second embodiment of the present invention. The detection device 115 according to the second embodiment of the present invention includes a triaxial acceleration sensor 121, a control unit 123, an ID generation unit 124, a transmission unit 125, a timer 126, a transmission antenna 127, and a water pressure sensor 128. And a water pressure determination unit 129. The triaxial acceleration sensor 121, the control unit 123, the ID generation unit 124, the transmission unit 125, the timer 126, the transmission antenna 127, and the power supply unit 130 are the triaxial acceleration sensor 21, the control unit 23, and the ID generation unit in the first embodiment. 24, the transmission unit 25, the timer 26, the transmission antenna 27, and the power supply unit 30, and the description thereof is omitted.

  In the second embodiment of the present invention, a water pressure sensor 128 and a water pressure determination unit 129 are further provided. The water pressure sensor 128 detects the surrounding water pressure, and the water pressure determination unit 129 determines whether the water pressure is greater than or equal to a predetermined value and whether the amount of change in water pressure is greater than or equal to a set value.

  When the typhoon or the like increases, the water level around the pier 12 rises, and the water pressure increases. Further, when the scouring protection block flows out, the posture and position of the scouring protection block changes with respect to the flow of water in the river, so that the water pressure received by the scouring protection block also changes. Therefore, in this embodiment, it is possible to further increase the reliability by detecting the surrounding water pressure and the change in the water pressure by the water pressure sensor 128 and determining the loss of the scour protection block 13. Further, when the water pressure determination unit 129 determines that there is a change in the water pressure and the water pressure that are greater than or equal to a predetermined value, the reliability can be further improved by shortening the interval of the timer 126.

  The present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 River 11 Bridge 12 Bridge pier 13 Scour protection block 15 Detection apparatus 16 Reception apparatus 17 Wireless network 18 Monitoring server 21 3-axis acceleration sensor 23 Control part 24 ID generation part 25 Transmission part 26 Timer 27 Transmission antenna 30, 130 Power supply part 31 Reception antenna 32 Reception processing unit 33 ID detection unit 34 Wireless interface unit 35 Wireless communication antenna

Claims (7)

A scouring protection block loss detection device that is provided in each of the scouring protection blocks installed around the pier, and judges whether there is an abnormality in the scouring protection block,
The acceleration detection device is an acceleration detection device that detects three-axis acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction;
A control device that determines the presence or absence of an abnormality in the scouring protection block using the magnitude of the inclination, the direction of the inclination, and the vibration obtained from the data of the triaxial acceleration detected by the triaxial acceleration detecting means. And a scouring protection block loss detection device.   The scouring protection block loss detection device according to claim 1, further comprising a transmitter that transmits its identification information and abnormality information by a low frequency electromagnetic wave having a frequency of 1 kHz to 10 kHz.   The scour protection block loss detection device according to claim 1 or 2, wherein the acceleration detection device is provided in a part of the scour protection block.   The scouring protection block loss detection device according to any one of claims 1 to 3, wherein the control device determines that an abnormality occurs when an inclination that has continued for a predetermined time is detected.   The scouring protection block loss detection device according to any one of claims 1 to 4, wherein the control device determines that an abnormality is detected when vibration of the protection block is detected. A scour protection block runoff detection system that detects runoff of multiple scour protection blocks installed around a pier,
Embedded in a plurality of scour protection blocks installed around the pier, and a scour protection block loss detection device that detects the loss of the scour protection block;
A transmission device and a reception device for transmitting a signal from the scour protection block loss detection device with a low-frequency electromagnetic wave;
An analysis means for analyzing data from the scour protection block loss detection device,
The scouring protection block loss detection device is
An acceleration detecting device for detecting acceleration applied to the buried scouring protection block;
It consists of a control device that determines the presence or absence of abnormality of the scouring protection block from the acceleration data detected by each acceleration detection device,
The control device determines whether or not there is an abnormality from acceleration data obtained from the acceleration detection device.   The scouring protection block loss according to claim 6, wherein the analysis means analyzes the number and position of scouring protection blocks determined to have the abnormality and determines the risk of the pier. Detection system.

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