JP4989310B2 - Reinforcing bar diagnostic equipment - Google Patents

Description

  The present invention relates to a reinforcing bar diagnostic apparatus for diagnosing the state of a reinforcing bar inside a reinforced concrete and a reinforcing bar diagnostic method using the same.

  In a structure using reinforced concrete, the strength is maintained by the strength of the concrete itself and the reinforcing bars existing inside the concrete. Therefore, it is necessary to grasp the condition of the concrete and the reinforcing bar itself for the maintenance and management of the reinforced concrete structure.

Among these methods, concrete deterioration can be confirmed by taking out a test piece from the concrete itself as well as checking for cracks and deposits that can be observed on the surface. In addition, diagnosing the number and deterioration of reinforcing bars existing inside is indispensable for ensuring the safety of the structure, but it is impossible to directly observe the reinforcing bars inside the concrete. Various non-destructive inspection devices using ultrasonic waves, magnetic fields (magnetic fields), electromagnetic waves, X-rays, etc. have been developed, manufactured and sold. Furthermore, the method of peeling concrete and confirming directly is also considered (refer nonpatent literatures 1-3).
Concrete Engineering March 1989, pp.48-47, 69-74 http://www.dnc.co.jp/technology/04hihakai_01.htm NTT Technical Journal, March 2006, pp.41-46

  However, the following (1) to (3) are problems in the conventional nondestructive inspection apparatus using ultrasonic waves, magnetic fields, electromagnetic waves, and X-rays.

(1) Handling and measurement procedures are complicated and specialized knowledge is required.
(2) The sensor and the oscillator are expensive, and the entire device is also expensive.
(3) Experience and knowledge are required to determine the measurement results using ultrasonic waves and the measurement results using magnetic fields.

  Moreover, although the method of peeling concrete and confirming the state of the inside reinforcing bar directly can also be considered, since it may impair the strength of the structure, it could not be said to be a realistic method.

  The object of the present invention has been made in view of the above, and can be used to observe the state of the reinforcing bar in the reinforced concrete so as to be visible using electrostatic coupling, and to accurately and easily diagnose the state of the reinforcing bar. An apparatus and a reinforcing bar diagnosis method using the same are provided.

In order to solve the above-mentioned problem, the present invention according to claim 1 is a rebar diagnostic apparatus for diagnosing a state of a reinforcing bar arranged inside a cylindrical reinforced concrete, wherein a high-frequency signal is transmitted to the reinforcing bar by electrostatic coupling. A signal applying unit for generating an induced voltage by applying a voltage, a voltage measuring unit for detecting and measuring the induced voltage generated in the reinforcing bar by electrostatic coupling, and a measurement result by the voltage measuring unit are displayed. Each of the signal applying unit and the voltage measuring unit is wound along the surface shape of the columnar reinforced concrete by arranging an electrode on a flexible substrate having flexibility. An electrostatic shield part is provided on a side parallel to the winding direction of the flexible board, and the flexible board is placed on both ends of the electrostatic shield part. It is equipped with an electrode joint that mechanically and electrically couples the opposite ends when wound around reinforced concrete, and the voltage measuring unit can measure a plurality of electrodes at the same time by arranging a plurality of electrodes on the flexible substrate. The data display unit can display a plurality of the measurement results as a voltage distribution similar to the plurality of positions .

According to a second aspect of the present invention, in the first aspect , the voltage measuring unit receives the detected induced voltage with a high input impedance and amplifies the amplified voltage, and the amplification unit performs the amplification. Output means for outputting the induced voltage to the outside, and a power source for supplying power necessary for the operation of the amplifying unit and the output means.

According to a third aspect of the present invention, in the second aspect , the voltage measurement unit is housed in a shield case capable of electrostatic shielding.

  According to the present invention, there is provided a reinforcing bar diagnostic apparatus and a reinforcing bar diagnostic method using the same, in which the state of the reinforcing bar in the reinforced concrete can be observed visually using electrostatic coupling, and the state of the reinforcing bar can be diagnosed accurately and easily. Can be provided.

<First Embodiment>
FIG. 1 shows a first embodiment of the present invention. This embodiment is an example for grasping the state of the reinforcing bar 7 existing on the wall surface, floor surface, ceiling surface, etc. of the structure made of reinforced concrete. Here, an example for the wall surface 8 made of reinforced concrete is shown. .

  FIG. 1 is a configuration diagram of the measurement system, which is a signal generator 1 for generating a high-frequency signal, electrostatically coupling to the reinforcing bar 7 and applying a voltage, and a concrete made of concrete having the reinforcing bar 7 inside. In order to cause electrostatic coupling between the wall surface 8 and the signal generator 1 by the connection cable 6 and to generate the electrostatic coupling with the reinforcing bar 7, the voltage applicator 2 is in contact with the wall surface 8 and is electrostatically coupled in contact with the wall surface 8. A voltage detector 4 for detecting a voltage generated in the reinforcing bar 7, a voltage measuring device 3 for receiving and measuring a detection value detected by the voltage detector 4 via the connection cable 6, and a voltage measuring device 3 And a display 5 for displaying the measurement result according to visibly.

  As shown in FIG. 1, a high-frequency signal having an arbitrary frequency from the lower limit frequency 1 kHz to the upper limit frequency 30 MHz generated by the signal generator 1 is applied to the electrode, shield layer, and shield frame of the voltage applicator 2 through the cable 6. Is done. In this case, the signal generator 1 may be a normal high-frequency oscillation circuit (for example, a general high-frequency oscillation circuit composed of a transistor or an operational amplifier, or an oscillation circuit using crystal). It is also possible to use a measuring instrument capable of generating precise and various waveforms such as those described above, or a more accurate signal generator 1 (signal generator). Since the reinforcing bar 7 in the wall surface 8 made of reinforced concrete or the like is difficult to see visually from the outside, electrostatic coupling is used as an indirect confirmation means.

  The operation is as follows.

  The signal voltage from the signal generator 1 is supplied to a voltage applicator 2 that can be electrostatically coupled without contact with the reinforcing bar 7. The voltage applicator 2 is configured on a thin plate substrate 11 as shown in FIG. A voltage application electrode 10 for applying a voltage is formed on the front surface of the plate-like substrate 11.

Furthermore, the surface plane of the diagnosis target is planar or slightly uneven, if such a spherical or the like, since the open type structure by attaching a voltage applicator 2 on the surface, as shown in FIG. 2 (b) A shield frame 12 for stabilizing the coupling around the electrode can be formed.

Alternatively, in the case of diagnosis of a columnar or columnar structure, the shield electrode frame 14 may be configured vertically as shown in FIG. 2 (c) so that it can be wound around. In addition, on the left and right sides, there may be provided an electrode joining metal fitting 15 to which the electrode 13 and the shield electrode frame 14 can be electrically and mechanically coupled when wound around a column. In this case, the plate-like substrate 11 is flexible.

  Further, an electrostatic shield electrode for eliminating the influence from the outside is formed on the back surface of the plate-like substrate 11, and when the diagnostic surface is a flat surface or a surface with some unevenness, a spherical surface or the like, the plate-like substrate 11. When the shield electrode is formed on the entire back surface of the substrate and the diagnostic surface is for a columnar or columnar structure, the shield electrode is formed on the entire surface of the plate-like substrate 11, and the shield electrode is electrically connected when wound around the column. It may have a function that can be mechanically and mechanically coupled.

  At this time, the material of the plate-like substrate 11 may be a hard and highly insulating material such as a plastic plate or wood, or a flexible material such as a plastic film, a flexible substrate, rubber, foamed plastic or the like. Further, in order to lower the dielectric constant of the plate-like substrate, a plate-like foam material may be used.

  Next, in FIG. 3B showing the cross section aa ′ in FIG. 3A, the output from the signal generator 1 is the center line covered with the insulator 25 in the coaxial cable of the connection cable 6. The voltage application electrode 20 is connected to the voltage application electrode 26. The ground side 27 of the signal generator 1 is connected to the shield outer wire 24 and the electrostatic shield electrode 23 of the connection cable 6 and the shield electrode frame 12 (not shown). Further, as shown in FIG. 3A, the voltage application electrode 20 is electrostatically coupled with the reinforcing bar 7 and the capacitance 30 by applying the voltage application electrode 20 to the wall surface.

  Thereby, an electrostatic induction voltage is generated in the reinforcing bar 7. Due to the generation of the induced voltage, the voltage level is different between the portion where the reinforcing bar 7 is present and the portion where the reinforcing bar 7 is not present, so that the potential distribution on the diagnostic surface changes. Furthermore, resistance and capacitance are generated in the part where the reinforcing bar 7 is broken inside, the part where the connecting point (welding point, joint) of the reinforcing bar 7 is present, and the part where the reinforcing bar 7 is deteriorated due to internal corrosion. Even if the reinforcing bars 7 are present, an abnormality occurs in the potential distribution.

  Further, by attaching a voltage detector 4 having a plurality of voltage detection electrodes for measuring a potential distribution around the voltage applicator 2 shown in FIG. 1 (in the case of a columnar shape, the upper and lower portions of the voltage applicator 2). It becomes possible to measure the potential distribution on the concrete surface (wall surface 8) where the applied voltage is generated.

  The voltage detection electrode of the voltage detector 4 is configured, for example, as shown in FIGS.

  First, as shown in FIG. 4A, a plurality of detection electrodes 40 are formed on a thin plate substrate 50, and a plurality of detection electrodes 40 for simultaneously measuring the distribution of a plurality of points are formed on the front surface of the plate substrate 50. When the surface to be diagnosed is a flat surface or a surface with a slight unevenness, a spherical surface, etc., since it is an open type structure in which the voltage applicator 2 is attached to the surface, detection is performed as shown in FIG. Shield frames 41 for stabilizing the coupling are formed around the electrodes 40, respectively.

  Alternatively, in the case of diagnosing a columnar or columnar structure, the shield frame 41 is also configured on the top and bottom as shown in FIG. 4C so that the structure can be wound around the object to be diagnosed. In addition, on the left and right, an electrode joint fitting 42 that can electrically and mechanically connect the shield frame 41 when wound around a pillar may be disposed. In this case, the plate substrate 50 is flexible.

  Further, a shield electrode (not shown) is formed on the back surface of the plate-like substrate 50 to eliminate external influences. When the diagnostic surface is a flat surface or a surface with some irregularities, a spherical surface, etc., the plate-like substrate When the shield electrode is formed on the entire back surface of the 50 and the diagnostic surface is for a columnar or columnar structure, the shield electrode is configured on the entire surface of the substrate, and the shield electrode is electrically or mechanically wound around the column. It may have a function that can be combined.

  At this time, the material of the plate-like substrate 50 may be a hard and highly insulating material such as a plastic plate or wood, or a flexible material such as a plastic film, a flexible substrate, rubber, foamed plastic or the like. Further, in order to lower the dielectric constant of the plate-like substrate, a plate-like foam material may be used.

  FIG. 5 is a schematic diagram of detection of the state of the reinforcing bar 7 on the wall surface 8. As shown in FIG. 5, by attaching the voltage detector 4 to the wall surface 8, the reinforcing bar 7 in the vicinity of each detection electrode 40 and the detection electrode 40 are electrostatically coupled, and the potential distribution on the diagnostic surface displayed on the display 5. Can be measured.

The equivalent circuit of this measurement system is simply represented as shown in FIG. In FIG. 6, the capacitance between the voltage application unit 52 and the reinforcing bar 53 is Ci, the equivalent inductance and equivalent resistance of the reinforcing bar 53 are Ls and Rs, and the capacitance between the reinforcing bar 53 and one voltage detection unit 54, respectively. Is Co. If the applied voltage of the signal generating unit 51 is Vi, the output of the voltage measuring unit 50 is Vo, and the input impedance of the measuring unit is a parallel circuit of a resistor Rp and a capacitor Cp, Vo is given by the following equation.

  However, it is assumed that there is no disturbance in the above equation, and the voltage application unit 52 and the voltage detection unit 54 have no shield electrode. From this equation (1), it can be confirmed that the measured voltage of the voltage measuring unit 50 changes as the resistance Rs and the inductance Ls of the reinforcing bar 53 change.

  For example, when the surface of the reinforcing bar 7 is corroded, the electrical conductivity of the rust portion is deteriorated, or the cross-sectional area is reduced as compared with a healthy reinforcing bar 7, so the resistance and inductance of that portion are large. Become. Further, even when the reinforcing bar 7 is partially broken, the resistance value and inductance of the portion change. As a result, it can be seen that when the rebar 7 is deteriorated, the potential obtained as an output is smaller than that in a healthy place.

  Therefore, by measuring the output from each electrode of the voltage detector 4 with the voltage measuring device 3 and displaying it as a distribution, the state of the reinforcing bars 7 in the concrete wall surface 8 can be diagnosed nondestructively.

<Second Embodiment>
FIG. 7A shows an example in which the present invention is applied to a columnar reinforced concrete structure as a second embodiment of the present invention.

  As shown in FIG. 7A, the voltage applicator 62 can be wound around the columnar structure 60, and the electrodes of the voltage applicator 62 can be electrically and mechanically connected. .

  Similarly, the voltage detector 63 can be wound around the columnar structure 60, and the shield electrode portion can be electrically and mechanically connected. The voltage applicator 62 and the voltage detector 63 are attached in a vertical relationship as shown in the figure, and the same is true in the reverse case.

  When a high frequency signal generated from the signal generator 1 is applied to the voltage applicator 62, an electrostatic voltage is generated in the reinforcing bar due to electrostatic coupling with the reinforcing bar 7. By detecting this voltage by electrostatic coupling with the voltage detector 63 and measuring with the voltage measuring device 3, the potential distribution in the region where the voltage detector 63 is wound can be measured.

  Further, when a plurality of voltage detection electrodes of the voltage detector 63 are arranged vertically and horizontally, the obtained potential distribution is high at a position where the reinforcing bar 7 is in the columnar structure 60 and is small at a portion where the reinforcing bar 7 is not present. Become. In the region where the voltage detector 63 is wound, when the reinforcing bar 7 is corroded or broken, when the position of the voltage applier 62 is lower than the position of the voltage detector 63, the winding of the voltage detector 63 is performed. In the case of the lower side of the region and vice versa, the potential distribution on the upper side becomes smaller.

  In the case of FIG. 7A, since the voltage applicator 62 is above the voltage detector 63, the potential of the portion without the reinforcing bar 7 in the columnar structure 60 (the lower part of the right reinforcing bar in FIG. 7A) is the highest. The lower reinforcing bar 7 in the region of the voltage detector 63 has a slight potential due to the coupling with the surrounding reinforcing bars 7 and is therefore higher than the portion without the reinforcing bars 7. Therefore, when the detected potential distribution is displayed, it becomes like the example of FIG. 7B, and the state of the reinforcing bar 7 can be grasped.

<Third Embodiment>
FIGS. 8A and 8B show an example in which a voltage detection circuit with a high input impedance is used as the voltage detection circuit 65 provided in the voltage measuring device 3 as a third embodiment of the present invention.

  FIG. 8A is a schematic view showing a state in which the voltage detector 70 is mounted on the wall surface 8 for measurement, and a cross section a-a ′ is shown in FIG. As shown in FIG. 8B, a voltage detection circuit 65 having a high input impedance is attached between the voltage detection electrode 21 and the shield electrode 23 sandwiching the plate substrate 22 in the voltage detector 70.

  The high input impedance voltage detection circuit 65 is composed of a parallel circuit of high resistance and capacitance of several hundred kΩ or more. For example, as a familiar example, a voltage probe or the like for connecting to an oscilloscope is a specific example. By making the input of the voltage measuring device 3 have a high input impedance, since almost no current flows from the equivalent circuit shown in FIG. 6, the power consumption is suppressed, and the current is generated at the position of each reinforcing bar 7. The detected voltage can be detected efficiently. The high input impedance voltage detection circuit 65 can be realized by a high input impedance circuit using an active element such as an FET.

<Fourth embodiment>
FIGS. 9A and 9B are configuration diagrams for explaining the fourth embodiment of the present invention. 9A and 9B, the voltage detector 70 attached to the wall surface 8, the shield case 71 attached integrally to the voltage detector 70, and the shield case 71 are disposed inside the shield case 71. An active voltage detection circuit 73 and a battery 74 for driving it are shown. The ground of the active voltage detection circuit 73 is connected to the shield case 71, and the connection terminal 72 is connected to the input side for voltage detection, and is connected to the voltage detection electrode 21 through the plate substrate 22. . The shield case 71 is connected to the electrostatic shield electrode 23 of the voltage detector 70. The output of the active voltage detection circuit 73 is sent to the outside through the connection cable 6.

  FIG. 9A having such a configuration is an example of a structure in which a shield case 71 incorporating an active voltage detection circuit 73 is attached to the voltage detector 70, and the internal structure thereof is shown in a perspective view. FIG. 9B shows the result.

  As shown in FIG. 9B, one end of the input of the voltage detection electrode 21 and the built-in active voltage detection circuit 73 is connected through the electrostatic shield electrode 23 and a minute hole formed in the plate-like substrate 22. Connected by terminals. The other input terminal of the active voltage detection circuit 73 is connected to the shield electrode. As a result, the voltage generated at the voltage detection electrode 21 can be measured. In addition, by attaching the shield case 71 to the electrostatic shield electrode 23, a decrease in voltage detection accuracy due to disturbance is prevented.

  The active voltage detection circuit 73 includes a battery 74 that supplies power for driving inside the shield case 71, and supplies power to the active voltage detection circuit 73. The power source is not limited to the battery 74, and for example, a power source supplied from the outside through a power line may be used.

  According to the embodiment of the present invention described above, a reinforcing bar diagnostic apparatus capable of observing the state of the reinforcing bar in the reinforced concrete so as to be visually recognized using electrostatic coupling, and accurately and easily diagnosing the state of the reinforcing bar, and the same It is possible to provide a method for diagnosing a reinforcing bar using

Explanatory drawing at the time of applying this invention to the wall surface based on embodiment of this invention is shown. An explanatory view for explaining an example of composition of a voltage application electrode is shown. An explanatory view for explaining voltage application to a wall surface concerning an embodiment of the invention is shown. An explanatory view for explaining an example of composition of a voltage detection electrode is shown. An explanatory view for explaining voltage detection using a plurality of voltage detection electrodes is shown. The equivalent circuit schematic which concerns on embodiment of this invention is shown. Explanatory drawing at the time of applying this invention to the columnar structure based on embodiment of this invention is shown. 1 shows a configuration example of a high input impedance voltage detection circuit according to an embodiment of the present invention. An example of the configuration of a voltage detection electrode provided with an active voltage detection circuit is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Signal generator 2 ... Voltage application device 3 ... Voltage measuring device 4 ... Voltage detector 5 ... Display device 6 ... Cable 7 ... Reinforcing bar 8 ... Wall surface 10 ... Voltage application electrode 11 ... Plate-shaped board | substrate 12 ... Shield electrode frame

Claims (3)

In the reinforcing bar diagnostic device for diagnosing the state of the reinforcing bars arranged inside the cylindrical reinforced concrete,
A signal applying unit for generating an induced voltage by applying a high frequency signal to the reinforcing bar by electrostatic coupling;
A voltage measuring unit for detecting and measuring the induced voltage generated in the reinforcing bar by electrostatic coupling;
A data display unit for displaying a measurement result by the voltage measurement unit ,
Each of the signal applying unit and the voltage measuring unit can be wound along the surface shape of the columnar reinforced concrete by arranging an electrode on a flexible flexible substrate, and the winding direction of the flexible substrate Electrostatic shield portions are provided on the sides parallel to each other, and at both ends of the electrostatic shield portions, electrode joints that mechanically and electrically couple opposite ends when the flexible substrate is wound around the columnar reinforced concrete With metal fittings,
The voltage measurement unit can measure a plurality of electrodes at the same time by arranging a plurality of electrodes on the flexible substrate,
The data display unit can display a plurality of measurement results as a voltage distribution similar to the plurality of positions, and the reinforcing bar diagnosis apparatus. The voltage measurement unit includes an amplification unit for receiving and amplifying the detected induced voltage with a high input impedance, an output unit for outputting the induced voltage amplified by the amplification unit to the outside, and rebar diagnostic apparatus according to claim 1, and a power supply for supplying power necessary for the operation of the amplifier and said output means, characterized in that it comprises at least a to. The reinforcing bar diagnosis apparatus according to claim 2 , wherein the voltage measurement unit is housed in a shield case capable of electrostatic shielding.

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