JP2006300809A - Structure inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure inspection device capable of detecting reliably and exactly response vibration by applying a percussion to a concrete structure to excite it, and capable of acquiring highly reliable internal information of the structure just under side of a percussion point easily in a short time. <P>SOLUTION: A hammer housing 5 is constituted into a cylindrical shape to store a hammer 3 for striking perpendicularly a concrete structure surface 1a, a ring-like under face of the hammer housing 5 is brought surely into contact with the structure surface 1a, a vibration sensor 7 is constituted of a magnetostrictive element comprising a metal magnetostrictive material (core) 21 and a coil 22 to form vertical arrangement of arraying the vibration sensor 7 and the hammer housing 5 along an axial direction, elastic vibration excited on the structure surface 1a by the percussion is transmitted via the hammer housing 5, and the axial-directional vibration is detected on the housing 5 by the vibration sensor 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure inspection apparatus for nondestructively inspecting internal deterioration of a concrete structure.

  Conventional nondestructive inspection methods for nondestructive inspection of internal deterioration of concrete structures include repulsion methods including continuous vibration method and vibration measurement method, and the object to be diagnosed is hit with a hammer etc. In addition, the pickup is installed at a position away from the excitation portion, the acoustic characteristics reaching the pickup from the excitation portion are detected by the pickup, and the detection signal is analyzed to thereby detect the object to be inspected. Deterioration is detected (see, for example, Patent Document 1).

  Further, in another conventional inspection apparatus for diagnosing the soundness of an object to be measured, a hammer for impacting the surface of a concrete structure, an acceleration sensor provided at a hammering portion of the hammer, and the acceleration It consists of a sensor and an analysis device connected so that signal transmission is possible. The surface of a concrete structure is struck with a hammer and the impact signal is collected by an acceleration sensor provided on the hammer and measured time history acceleration signal. Into the analyzer. Then, the initial hitting speed of the hitting hammer is calculated by integrating the time history acceleration signal with respect to time. Also, the time history striking force F generated on the surface of the structure by striking is obtained by multiplying the hammer mass by the measured acceleration, and the value obtained by dividing this time history striking force by the hammer's initial striking velocity This is referred to as impedance, and the soundness of the object to be measured is diagnosed from the obtained contact impedance (see, for example, Patent Document 2).

Japanese Laid-Open Patent Publication No. 7-280797 (second page) JP 2004-144586 A

  In the conventional non-destructive inspection as described above, the object to be inspected is struck and vibrated, and the acoustic characteristic reaching the pickup from this oscillating portion is detected, and the striking mechanism and its vibration response are received. The detection mechanism is composed of separate modules, and the strike point and the detection point are separated from each other. For this reason, the vibration response of the object to be inspected is obtained at a point on the circumference centered on the impact point, that is, only a partial response transmitted in one direction is obtained, and an accurate response just below the impact point is obtained. Can't get. When the hit point and the detection point sandwich a deformation such as a crack existing in the surface layer portion of the object to be inspected, it may be impossible to receive and measure the vibration response. Thus, it has been difficult to reliably detect deterioration of the object to be inspected.

  Moreover, in the conventional inspection device that collects the impact signal with the acceleration sensor provided on the hammer, the sensor is installed on the hammer side, so the response signal of the structure itself such as vibration generated on the structure surface by the hammer It is not something to collect. For this reason, there has been a problem that the analysis processing for obtaining and diagnosing the contact impedance used as the standard for soundness diagnosis is complicated. Moreover, even if the deformation of cracks, jumpers, etc. and the generation of cavities inside the concrete structure can be detected, it is difficult to detect the generation position from the surface layer.

  The present invention was made to solve the above-described problems. The concrete structure, which is an object to be inspected, is struck and vibrated, and its response vibration is detected accurately and accurately. Then, it aims at obtaining the structure inspection apparatus which can acquire easily the reliable internal information of the structure just under a striking point in a short time.

  A structure inspection device according to the present invention is excited on a surface of a concrete structure by a hammer that strikes the surface of the concrete structure in a direction substantially perpendicular to the surface (hereinafter referred to as an axial direction), and the hammer. Vibration transmission means for uniformly collecting and transmitting vibrations from around the hammer hit point of the hammer, and a vibration sensor for detecting the vibration transmitted by the vibration transmission means disposed in the upper axial layer of the hammer. Then, the deterioration of the concrete structure immediately below the hitting point by the hammer is inspected by the vibration detected by the vibration sensor.

  In the structure inspection apparatus according to the present invention, vibration transmitting means for uniformly collecting and transmitting vibration excited on the surface of the concrete structure by the hammer from around the hammering point of the hammer, and vibration disposed in the axial upper layer of the hammer. Because it is equipped with a sensor, it can accurately collect and detect the response vibration of the structure itself immediately below the impact point, can obtain highly reliable internal information of the structure immediately below the impact point, and highly accurate structure inspection Can be easily done in a short time.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below.
FIG. 1 is a block diagram showing a schematic configuration of a structure inspection apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, a structure inspection apparatus 2 for inspecting a concrete structure 1 includes a hammer 3 that strikes the structure 1, and a vibration transmission means that houses a pull-back spring 4 that pulls the hammer 3 back to an initial starting position. A cylindrical hammer housing 5, a coil 6 arranged around the hammer housing 5 for accelerating and sliding the hammer 3 in the hammer housing 5 with respect to the structure 1, and the structure surface ( And a vibration sensor 7 for detecting the vibration of the concrete structure 1 excited on the surface to be measured 1a). Further, a power supply device 8 for driving the coil 6, a hitting start switch 9, and a hitting control device 10 for setting and controlling hitting conditions of the hammer 3 are provided. Furthermore, a receiving device 11 that receives a detection signal from the vibration sensor 7 and processes it as necessary, and a display device 12 that displays an inspection result based on the received signal are provided.

  The structure inspection apparatus 2 is installed so that the hammer 3 strikes the measurement target surface 1a in the vertical direction. At this time, the ring-shaped lower surface of the cylindrical hammer housing 5 facing the measurement target surface 1a is: It is assumed that the surface to be measured 1a is surely contacted. The vibration sensor 7 is installed on the hammer housing 5 on the upper layer in the axial direction of the hammer 3 and the hammer housing 5, and detects the vibration transmitted by the hammer housing 5 on the hammer housing 5. The material constituting the hammer 3 is a magnetic material.

Next, the operation of the structure inspection apparatus 2 when inspecting the concrete structure 1 will be described.
When the impact activation switch 9 is turned on by the inspector, power is supplied from the power supply device 8, and the impact control device 10 applies the coil 6 disposed around the hammer housing 5 once or a plurality of times at a constant cycle. A drive voltage is applied. When a drive voltage is applied to the coil 6, a current flows through the coil 6 and a magnetic field is generated inside the hammer housing 5. Due to the magnetic force of the generated magnetic field, the hammer 3 made of a magnetic material accelerates and slides in the hammer housing 5 in the axial direction toward the surface to be measured 1a and strikes the surface to be measured 1a. The impact control device 10 controls the timing of applying the drive voltage, and cuts off the drive voltage by signal input from a sensor (not shown) that detects the hammer passing position. As a result, the hammer 3 effectively strikes the surface to be measured 1a, and then is pulled back by the pull-back spring 4 connected to the hammer 3 to return to the initial position.

  The concrete structure 1 is elastically vibrated by hitting the hammer 3, and the elastic vibration excited on the surface to be measured 1a is transmitted from the ring-shaped lower surface of the hammer housing 5 contacting the periphery of the hammering point of the hammer 3 through the cylindrical side surface. Is transmitted. The vibration sensor 7 detects the transmitted vibration on the hammer housing 5. The detection signal from the vibration sensor 7 is transmitted to the receiving device 11 and filtered by the receiving device 11, and the inspection result corresponding to the response level in the set frequency band of several KHz or less is displayed on the display device 12 according to the color such as LED. indicate. Of the elastic vibrations excited on the surface to be measured 1a and detected on the hammer housing 5, elastic vibrations in a low frequency band of several KHz or less are useful for diagnosing abnormalities, and concrete such as tunnels and road slabs are used. It is possible to inspect the structure such as internal deformation of the structure and soundness diagnosis of concrete.

In this embodiment, the cylindrical hammer housing 5 is used as a signal transmission means, and the vibration sensor 7 is installed on the hammer housing 5 in the upper layer in the axial direction. As described above, the cylindrical hammer housing 5 and the vibration sensor 7 are arranged side by side in the axial direction, so that the elastic vibration excited on the surface to be measured 1a is evenly collected from around the hammering point of the hammer 3 and vibrated. The vibration sensor 7 detects vibration on the hammer housing 5. For this reason, the response vibration of the structure itself immediately below the hitting point can be collected and detected evenly and accurately without being biased in the circumferential direction, and highly reliable internal information of the structure immediately below the hitting point can be obtained.
In addition, in order to make the hammer housing 5 cylindrical and ensure that the ring-shaped lower surface is in contact with the surface to be measured 1a, the response vibration of the structure itself immediately below the striking point is collected evenly without being biased in the circumferential direction. It is easy and surely possible to transmit the vibration sensor 7 to the position where the vibration sensor 7 is installed.

  In the above embodiment, the cylindrical hammer housing 5 is used as the signal transmission means. However, the elastic vibration excited on the surface to be measured 1a is collected evenly from the periphery of the hammering point of the hammer 3 without being biased in the circumferential direction. As long as it can transmit to the position where the vibration sensor 7 on the upper layer in the axial direction is installed, the shape of the hammer housing 5 may be changed, and the signal transmitting means may be configured separately from the hammer housing that houses the hammer 3.

Embodiment 2. FIG.
In the structure inspection apparatus 2 according to the first embodiment, the vibration sensor 7 using a magnetostrictive element is shown.
The vibration sensor 7 shown in FIG. 2 uses a metal magnetostrictive material whose permeability changes due to the action of bending strain, and stacks a plurality of sensor cores 21 in which thin plates are formed into a core shape, and coils 22 having a predetermined number of turns on both legs. Deploy.
The vibration sensor 7 configured as described above can detect the vibration in the direction indicated by the arrow 23 in the drawing. An electromotive force is generated in the coil 22 in accordance with the change in the magnetic permeability of the core 21 due to the action of distortion. The greater the strain, the greater the change in permeability, and the higher the voltage generated in the coil 22 as a result. That is, by obtaining an electric signal generated in the coil 22, vibration proportional to the electric signal is detected.

  In the structure inspection apparatus 2, the vibration sensor 7 using the magnetostrictive element as described above is installed on the hammer housing 5 in the vertical direction so that the strain detection direction 23 matches the axial direction. As a result, the vibration in the axial direction transmitted by the hammer housing 5 can be directly detected by the vibration sensor 7 as axial distortion, and the detection of the vibration with good detection sensitivity and high accuracy can be realized. In addition, the vibration sensor 7 using this magnetostrictive element can obtain vibrations of 10 KHz or less particularly with high detection sensitivity, and can effectively inspect a concrete structure.

Embodiment 3 FIG.
The third embodiment of the present invention will be described below.
In the structure inspection apparatus 2 shown in the first embodiment, the data analysis apparatus 13 is connected to the reception apparatus 11 as shown in FIG.
As in the first embodiment, the concrete structure 1 is elastically vibrated by the hammer 3 and the elastic vibration excited on the surface to be measured 1a is transmitted from the ring-shaped lower surface of the hammer housing 5 through the cylindrical side surface. The vibration sensor 7 is detected on the hammer housing 5. A detection signal from the vibration sensor 7 is transmitted to the receiving device 11, filtering is performed by the receiving device 11, and a frequency response waveform is input to the data analyzing device 13.

The frequency response waveform input to the data analysis device 13 is subjected to frequency analysis (FFT) processing to detect the maximum value of vibrations in the frequency band of 500 Hz to 10 KHz, and using the frequency, the boundary of the measurement point portion that is the hit point The concrete thickness up to the surface, for example, the lining thickness in the tunnel is calculated. In addition, the data analysis device 13 performs an integral calculation process of vibration between specific frequency bands, compares the total vibration level with a table indicating a preset reference value, and obtains information directly under the impact point from the process result. That is, the deterioration of the concrete structure 1 is diagnosed by obtaining the internal deformation of the measurement point part and the depth information from the surface layer. Moreover, these analysis results may be used for obtaining information such as deterioration with time during inspection by recording.
The display device 12 can select and display both the information from the receiving device 11 and the analysis result of the data analysis device 13 as displayable.

  In this embodiment, since the data analysis device 13 for analyzing the frequency response waveform of the vibration detected by the vibration sensor 7 using the frequency analysis (FFT) process and the display device 12 for displaying the analysis result are provided, the concrete structure is provided. Analysis of information related to the deterioration of the object 1 can be promptly performed on the spot and can be informed to the inspector. Further, since the vibration sensor 7 analyzes based on a reliable detection signal in which vibration is directly detected on the hammer housing 5, it is complicated as in a conventional inspection device that collects information with an acceleration sensor provided in the hammer. Analysis can be performed without requiring arithmetic processing. In addition, internal deformation of the measurement point region and depth information from the surface layer can be obtained, and a highly accurate and reliable inspection of the concrete structure can be performed.

Embodiment 4 FIG.
The fourth embodiment of the present invention will be described below.
In the structure inspection apparatus 2 shown in the third embodiment, as shown in FIG. 4, the pressing control mechanism 14 that presses the hammer housing 5 and the lower surface of the hammer housing 5 are pressed against the surface to be measured 1 a of the concrete structure 1. And a sensor 15 for detecting the pressing force.
Similar to the first and third embodiments, elastic vibration is applied to the concrete structure 1 by striking the hammer 3, and at this time, the ring-shaped lower surface of the cylindrical hammer housing 5 facing the surface to be measured 1a is It is necessary to be surely brought into contact with the surface to be measured 1a. In this embodiment, the pressing control mechanism 14 presses the hammer housing 5 against the surface to be measured 1a with a predetermined pressing force so that the lower surface of the hammer housing 5 is pressed against the surface to be measured 1a. The pressing force is controlled so that the pressure detected by the sensor 15 becomes a predetermined value.

  In this way, elastic vibration is applied to the concrete structure 1 by hitting the hammer 3 in a state where the hammer housing 5 is pressed against the surface to be measured 1 a by the pressing control mechanism 14. Thereby, the ring-shaped lower surface of the hammer housing 5 is reliably brought into contact with the surface to be measured 1a, and the elastic vibration excited on the surface to be measured 1a is transmitted from the ring-shaped lower surface of the hammer housing 5 through the cylindrical side surface. Is reliably transmitted and detected. For this reason, the vibration detection accuracy by the vibration sensor 7 is improved, and the reliability of the inspection accuracy is improved.

  The pressing control mechanism 14 as described above can be realized by a structure equipped with a compression buffer mechanism such as a spring or a structure equipped with an air damper mechanism.

  Further, the pressing control mechanism 14 is provided with a trigger means, and when the pressing force at which the lower surface of the hammer housing 5 is pressed against the surface to be measured 1a of the concrete structure 1 reaches a predetermined pressure, the impact activation switch 9 is turned on. Then, the hammer 3 may strike the surface to be measured 1a and start the inspection. Thus, the inspection can be automatically and quickly started in a state where the ring-shaped lower surface of the hammer housing 5 is reliably in contact with the surface to be measured 1a.

Embodiment 5. FIG.
The fifth embodiment of the present invention will be described below.
The structure inspection apparatus 2 according to the first embodiment includes the power supply device 8 for driving the coil 6, the impact activation switch 9, and the impact control device 10 for setting and controlling the impact condition of the hammer 3. Although a voltage is applied, in this embodiment, as shown in FIG. 5, it is set so that a plurality of types (three types in this case) of voltage levels can be supplied from the power supply device 8, and the voltage switching selection switch 16 is set as a switch. Use to select the voltage level and start. The batting control device 10 controls the batting condition according to each selected voltage level.

  The power supply device 8 and the voltage changeover selection switch 16 constitute a means for selecting a hammering force of the hammer 3, and an inspection impacting force for inspecting the deterioration of the concrete structure 1 is larger than the inspection impacting force. It is possible to select and set the peeling striking force for forcibly peeling the surface of the concrete structure 1 with the striking force. In this case, three voltage levels are provided in two stages for obtaining a striking force for peeling and a voltage level for obtaining a striking force for inspection and a voltage level higher than that.

Next, operation | movement of the structure inspection apparatus 2 comprised in this way is demonstrated.
When the voltage selector switch 16 is turned on by the inspector selecting a voltage level for obtaining the impact force for inspection, power is supplied from the power supply device 8 and the drive voltage controlled by the impact control device 10 is applied to the coil 6. To be applied. As a result, the hammer 3 accelerates and slides in the hammer housing 5 in the axial direction toward the surface to be measured 1a, strikes the surface to be measured 1a with an inspection striking force, and is pulled back by the retracting spring 4 to return to the initial position.

  The concrete structure 1 is elastically vibrated by the hammer 3 and the vibration sensor 7 detects the elastic vibration excited on the surface to be measured 1 a on the hammer housing 5. A detection signal from the vibration sensor 7 is transmitted to the receiving device 11 and filtered by the receiving device 11, and an inspection result corresponding to a response level in a set frequency band of several KHz or less is displayed on the display device 12. Further, as shown in the third embodiment, the frequency response waveform is input to the data analysis device 13, and analysis processing is performed using frequency analysis (FFT) processing to diagnose deterioration of the concrete structure 1 and display it. Display on the device 12.

If there is a possibility that the surface of the concrete structure 1 is peeled off or the concrete cover part is peeled off from the displayed inspection results and analysis results, the inspector forcibly peels the surface of the concrete structure 1 To continue.
When the voltage selector switch 16 is turned on by the inspector selecting a voltage level for obtaining the striking force for peeling, power is supplied from the power supply device 8 and the drive voltage controlled by the striking control device 10 is applied to the coil 6. To be applied. The hammer 3 impacts and vibrates the corresponding portion of the surface to be measured 1a with the striking force with increased striking energy, and then is pulled back by the pulling spring 4 to return to the initial position. By hitting the hammer 3, the surface concrete portion is knocked down.

When there are a plurality of types of voltage levels for the peeling striking force, they are determined according to the displayed inspection result and analysis result.
Further, in the case of the forced peeling process, a normal process for detecting and inspecting the vibration with the vibration sensor 7 after being hit by the hammer 3 is performed as necessary.

  In this embodiment, the striking force of the hammer 3 can be selected, and the striking force for inspecting the deterioration of the concrete structure 1 and the striking force for forcibly peeling the surface can be selected. Therefore, the forced peeling process can be performed using the structure inspection apparatus 2 for the inspection, and the forced peeling process can be easily and easily performed without requiring a special apparatus for the forced peeling. . In addition, since the inspection and the forced peeling treatment can be continuously performed using the same apparatus, it is possible to cope with the problem very efficiently when there is a possibility that the inspection portion is peeled off or peeled off.

It is the block diagram which showed schematic structure of the structure inspection apparatus by Embodiment 1 of this invention. It is a figure which shows the structure of the vibration sensor by Embodiment 2 of this invention. It is the block diagram which showed schematic structure of the structure inspection apparatus by Embodiment 3 of this invention. It is the block diagram which showed schematic structure of the structure inspection apparatus by Embodiment 4 of this invention. It is the block diagram which showed schematic structure of the structure inspection apparatus by Embodiment 5 of this invention.

Explanation of symbols

1 Concrete structure, 1a Structure surface (surface to be measured), 2 Structure inspection device,
3 hammer, 5 hammer housing as vibration transmission means, 7 vibration sensor,
DESCRIPTION OF SYMBOLS 8 Power supply device, 12 Display apparatus, 13 Analysis apparatus, 14 Press control mechanism, 15 Sensor, 16 Voltage change selection switch as a striking force selection means, 21 Magnetostrictive material (core),
22 Coil.

Claims (8)

A hammer that strikes the surface of the concrete structure in a direction substantially perpendicular to the surface (hereinafter referred to as an axial direction), and vibrations excited by the hammer on the surface of the concrete structure from around the hammering point of the hammer A vibration transmitting means for uniformly collecting and transmitting; and a vibration sensor for detecting vibration transmitted by the vibration transmitting means disposed on an upper layer in the axial direction of the hammer, and the vibration detected by the vibration sensor A structure inspection device for inspecting deterioration of the concrete structure just below the hitting point by a hammer. A magnetostrictive element composed of a core and a coil made of a metal magnetostrictive material whose permeability changes due to bending strain is used for the vibration sensor, and vibration detection by the vibration sensor is generated by vibration transmitted by the vibration transmitting means. The structure inspection apparatus according to claim 1, wherein the inspection is performed by detecting an axial strain of the magnetostrictive element. The vibration transmitting means is constituted by a cylindrical hammer housing for housing the hammer, and the ring-shaped lower surface of the hammer housing is brought into contact with the surface of the concrete structure so that vibration is evenly distributed from around the hammer hit point. The structure inspection apparatus according to claim 1, wherein the vibration is collected and transmitted through a side surface of the hammer housing. The structure inspection apparatus according to any one of claims 1 to 3, further comprising a pressing control means for pressing the hammer housing so that a lower surface of the hammer housing is pressed against the surface of the concrete structure. . Trigger means for inspecting deterioration of the structure by the hammer hitting the surface of the concrete structure when the pressing force with which the lower surface of the hammer housing is pressed against the surface of the concrete structure reaches a predetermined pressure 5. The structure inspection apparatus according to claim 4, wherein the pressure control means is provided. A means for selecting a hammering force of the hammer, an inspection striking force for inspecting deterioration of the concrete structure, and a peeling for forcibly peeling the surface with a striking force larger than the striking force for the inspection The structural inspection apparatus according to any one of claims 1 to 5, wherein an impact force can be selected and set. The structure inspection apparatus according to claim 1, wherein the vibration sensor detects elastic vibration in a low frequency band equal to or lower than a predetermined frequency. 8. An analysis device for analyzing vibration detected by the vibration sensor using frequency analysis processing and diagnosing deterioration of the concrete structure, and a display unit for displaying the analysis result. The structure inspection apparatus according to any one of the above.

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