JP2013253947A - Inspection method of concrete structure, and inspection device of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and an inspection device by which an unsound part of concrete can be detected precisely with extremely high accuracy.SOLUTION: An inspection method of concrete structure includes the steps of: putting a polygonal head 2 on the surface of concrete structure while moving the polygonal head 2; analyzing a change in strength of rotating/hitting sound to a distribution of frequencies of the rotating/hitting sound generated by the movement of the polygonal head 2; and determining a part having the rotating/hitting sound larger than that of other parts as an unsound part. Accordingly, a peak part of the rotating/hitting sound can be easily found, and the peak part can be easily determined as the unsound part of the concrete structure.

Description

  The present invention relates to a concrete structure inspection method and a concrete structure inspection apparatus capable of easily finding a defective portion of a concrete structure such as a building, a bridge, or a tunnel inner wall.

  In the method of inspecting a concrete structure, an operator listens to the sound generated by hitting with a hammer or the like, and the presence or absence of a defect is discriminated by human sense. In this case, the work efficiency is low, and it is practically difficult to inspect long structures such as highways and bullet trains. Moreover, there is a difference in the judgment of pass / fail for each worker, and qualitative judgment is difficult.

  For this reason, for example, there is one disclosed in Patent Document 1. This comprises a rolling element that is rotatably supported at the tip of the operating rod and rolls while contacting a surface of a structure or the like made of a concrete structure. This rolling element is a polygon having a cross-sectional outer shape of 5 to 8 sides, and its outer peripheral surface is a cylindrical surface or an elliptical cylindrical surface having 5 to 8 sides.

  And what was disclosed by patent document 1 is equally divided | segmented into the rolling surface, and the rolling detected by the microphone for detecting the rolling sound which is generated when the rolling element rolls on the surface of the inspection object. Based on the hitting sound, the rolling sound analysis unit automatically determines a healthy part and an unhealthy part.

  This has the effect of increasing the efficiency of the inspection and eliminating the difference in judgment for each worker.

JP, 2007-132720, A

In the apparatus disclosed in Patent Document 1, whether a concrete structure to be inspected is healthy or unhealthy is determined by a rolling sound analysis unit using a microcomputer or the like.
For this determination, a portion where the frequency of the tapping sound picked up from the microphone is attenuated is attenuated, and it is determined whether or not the sound pressure level of the tapping sound exceeds the first threshold value Sa. However, when the first threshold value Sa is exceeded, the second threshold value Sb that is lower than the first threshold value Sa is exceeded in a predetermined period Tb after a predetermined time Ta from the time point ta when the first threshold value Sa is exceeded. If the second threshold value Sb is exceeded, it is determined that it is an unhealthy part.

  Although what was disclosed by such patent document 1 is markedly improved rather than discriminating whether a concrete structure is healthy or unhealthy by a human hearing, this invention is further improved with a healthy part and an unhealthy part. Is to be able to discriminate accurately.

  In order to solve the above-described problems, the present invention moves while applying a polygonal head to the surface of a concrete structure, and changes in the strength of the rolling sound with respect to the frequency distribution of the rolling sound generated thereby. Was analyzed, and the part where the strength of the rolling sound was stronger than the other part was discriminated as an unhealthy part.

  Since the concrete structure inspection method of the present invention is configured as described above, it is possible to accurately detect an unhealthy portion of concrete. In particular, when the concrete is changing with time, the overall strength of the rolling noise is different from that of the initial concrete. Even in such a case, if there is an unhealthy part in the concrete structure, such as the deterioration of a specific part, expansion due to corrosion of a reinforcing bar, or the occurrence of a cavity, the impact sound of other parts Since it is determined by comparison with other portions, detection with extremely high accuracy is possible.

  In addition, this inspection method can be easily mechanized by frequency analysis means using a computer. Furthermore, since such frequency analysis means can partially use commercially available software for a computer, the present invention can be easily implemented.

  And since it can mechanize in this way, the difference of the data which approaches the operator who performed the inspection work is eliminated, and the inspection data can be standardized. For this reason, it is possible to standardize a new completion inspection standard for a concrete structure and a safety inspection for a concrete structure after a long period after construction.

  For this reason, it is possible to quickly and accurately determine the earthquake resistance of old structures so that unhealthy parts of concrete can be quickly detected and dealt with in the anticipated current situation of a huge earthquake. This is extremely important for resolving social anxiety, and can be realized by the present invention.

  It is a front view of the hammer part used for the concrete structure inspection apparatus of this invention.   It is a side view of the hammer part of the concrete structure inspection apparatus of this invention.   It is a circuit block diagram of the concrete structure inspection apparatus of the present invention.   It is a figure which shows the change of the sound pressure level obtained by the concrete structure inspection apparatus of this invention.   It is a figure which shows the frequency distribution and sound pressure peak which were obtained by the concrete structure inspection apparatus of this invention.   It is a figure which shows the change of the sound pressure level obtained by the concrete structure inspection apparatus of this invention.   It is a figure which shows the frequency distribution obtained by the concrete structure inspection apparatus of this invention.   It is a figure which shows the relationship of the frequency / sound pressure level obtained with the concrete structure inspection apparatus of this invention.

  According to the first aspect of the present invention, a hammer portion having a polygonal cross-section head rotatably attached thereto is rotated against a wall surface of a concrete structure to be inspected, and a head hitting sound generated thereby is rotated. That is, by detecting the sound produced by the head and the concrete wall surface, and displaying the part where the sound pressure level of the specific part is high with respect to the frequency distribution of the tapping sound as an image, the concrete structure This is a method for inspecting a concrete structure in which an abnormal (unhealthy) part of an object is discovered, and has an effect that an unhealthy part can be easily identified.

  Embodiments of the concrete structure inspection method of the present invention will be described in detail below with reference to the drawings. The apparatus used for the concrete structure inspection method of the present invention will be described first, and then the inspection method will be described.

  FIG. 1 is a front view of a hammer portion 1 used in a concrete structure inspection apparatus of the present invention. Reference numeral 2 denotes a head having a hexagonal cross section. The head 2 is rotatably attached to the shaft 3, and the microphone 4 is attached to the shaft 3. The shaft 3 has a telescopic structure and can be expanded and contracted.

  That is, as shown in FIG. 2, when the head 2 is moved while being applied to the wall surface of the concrete structure 4 that is an inspection object, the head 2 has a hexagonal cross section, so that a rolling sound is generated. This tapping sound is picked up by the microphone 4.

  FIG. 3 shows a circuit block diagram of the concrete structure inspection apparatus of the present invention. The audio signal from the microphone 4 is converted into a digital signal by an analog / digital converter 5 (hereinafter referred to as “A / D”). Since the A / D 5 is already configured with an integrated circuit and is generally commercially available, detailed description thereof is omitted.

  The audio signal digitized by the A / D 5 enters the central processing unit (hereinafter referred to as “CPU”) 7 through the data buffer 6. The CPU 7 operates in accordance with the OS and application software (hereinafter referred to as “application”) stored in the operation software (hereinafter referred to as “OS”) storage memory 8.

  The data storage memory 9 stores data obtained by digitizing audio signals. A random access memory (hereinafter referred to as “RAM”) 10 temporarily stores data during the operation of the CPU 7. The calculation result processed by the CPU 7 using the data in the data storage memory 9 and the data digitized by the A / D 5 is displayed on a liquid crystal display (hereinafter referred to as “LCD”) via the display driver 10. 11 is displayed.

  The operation of the concrete structure inspection apparatus of the present invention configured as described above will be described below. First, the tapping sound picked up from the microphone 4 is sent to the CPU 7 via the buffer 6, and the change with time of the frequency characteristic is analyzed. The results of actual experiments on the change in frequency characteristics over time are shown in FIGS. The data shown in FIGS. 4 to 7 are measured by using a model in which a cavity is formed inside a concrete structure and partially peeled.

  4 and 5 are based on a peeling model having a thickness of 30 mm, and FIGS. 6 and 7 are based on a peeling model having a thickness of 50 mm. 4 and 6, the horizontal axis indicates the distance from the end of the specimen, and the vertical axis indicates the sound pressure. As apparent from FIGS. 4 and 6, the duty of the audio signal is increased in a specific portion. And it turns out that this range is the range which peeled.

  Further, as apparent from FIGS. 5 and 7, the frequency distribution of the audio signal is narrow in a specific portion. This range coincides with the range in which the audio signal duty is large in FIGS. 4 and 6, and it can be seen that this range is a separated range.

  Next, FIG. 8 shows the result of frequency analysis of the data of the tapping sound, with the horizontal axis representing frequency and the vertical axis representing sound pressure level. This graph is obtained by analyzing the spectrum of a tapping sound with a cavity depth of 40 mm, and is drawn by superposing 10 analysis graphs. From this, it can be seen that the characteristics are almost the same even 10 times. All analysis graphs show four prominent peaks. These four prominent peaks indicate that a cavity or the like is formed in the specimen subjected to this experiment, and a resonance wave is generated by a reflected wave from the boundary between the cavity and the normal part.

  By displaying the test results of FIGS. 4 to 8 on the LCD 11 of the concrete structure inspection apparatus of the present invention, the operator can easily detect an abnormal portion of the concrete structure. That is, an abnormal (unhealthy) portion of the concrete structure can be found by detecting a portion where the sound pressure level of a specific portion is high with respect to the frequency distribution of the tapping sound.

  Although the concrete structure inspection apparatus and the concrete structure inspection method of the present invention have been clarified by the above description, in some cases, a program for pattern recognition by the CPU 7 is stored, and an unhealthy location is automatically found. It is also possible to do so.

  Further, the rolling sound data of the head 2 is stored in the data storage memory 9 and can be reconfirmed after sampling the rolling sound, thereby improving the reliability of the test result. In the above embodiment, the hammer 2 has a hexagonal cross section. However, depending on the concrete structure to be inspected, an appropriate shape exists in the range of about 5 to 10 squares. The point is to make it possible to detect unhealthy parts of a concrete structure by rolling noise, and to make the shape according to it.

  The present invention can provide an inspection method capable of detecting an unhealthy location such as a cavity of a concrete structure quickly and accurately.

1 Hammer 2 Head 3 Shaft 4 Microphone 5 A / D
6 Data buffer 7 CPU
8 OS storage memory 9 Data storage memory 10 RAM
11 Display driver 12 LCD

Claims (5)

  A hammer with a polygonal cross-section head rotatably attached to the wall surface of the concrete structure to be inspected is rotated, and the head hitting sound generated thereby is detected, and the frequency distribution of the hitting sound is obtained. On the other hand, a method for inspecting a concrete structure that detects an abnormal (unhealthy) portion of a concrete structure by detecting a portion where the sound pressure level of a specific portion is high.   The method for inspecting a concrete structure according to claim 1, wherein the tapping sound is picked up by a microphone, the sound data output from the microphone is digitally converted, and the frequency analysis is performed by a computer.   3. The method for inspecting a concrete structure according to claim 2, wherein the result of the frequency analysis is displayed on a display device so that an abnormal (unhealthy) portion of the concrete structure can be found visually by an inspection worker.   A hammer section rotatably mounted with a polygonal cross-section head so as to roll on the wall of the concrete structure to be inspected; a microphone for picking up the rolling sound emitted by the head; and the microphone And a microcomputer for frequency analysis of the digitized voice data, and the microcomputer has a sound pressure level with respect to a frequency change of the voice data. A concrete structure inspection device that detects parts larger than other parts.   5. The concrete structure inspection apparatus according to claim 4, further comprising a data storage memory for storing digitized audio data.

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