System and program for evaluating voids in concrete structures

Abstract

This invention provides a concrete structure void evaluation system and program capable of automatically and accurately evaluating voids in concrete structures. [Solution] The void evaluation system and program for concrete structures is characterized by comprising: a reference signal acquisition unit that acquires a reference signal including a first impact sound of the concrete structure; an evaluation signal acquisition unit that acquires an evaluation signal including a second impact sound of the concrete structure that is different from the first impact sound; and a void evaluation unit that evaluates the voids of the concrete structure based on the reference signal acquired by the reference signal acquisition unit and the evaluation signal acquired by the evaluation signal acquisition unit.

Description

[Technical Field]

[0001] This invention relates to a system and program for evaluating voids in concrete structures. [Background technology]

[0002] Traditionally, diagnosing voids such as cracks and delamination in concrete structures like bridges and buildings has been extremely important in the fields of architecture and civil engineering. Voids in concrete structures negatively impact the safety and durability of the structure. For example, if voids in a concrete structure are left untreated, not only will the durability of the concrete decrease, but it may also accelerate the deterioration of surrounding concrete structures. Furthermore, if voids are left untreated, the concrete structure may eventually spall or fall off, potentially leading to serious accidents. Therefore, it is necessary to detect and repair these voids as early as possible.

[0003] Tapping tests are used to diagnose voids in concrete structures. In a tapping test, a worker manually strikes the concrete structure and diagnoses the voids by listening to the sound. While tapping tests can quickly diagnose a wide area, the accuracy of the diagnosis depends on the experience and skill of the worker, which can lead to variability in the test results. Furthermore, there is a risk that concrete structures may not be adequately inspected if there is a shortage of workers capable of performing tapping tests.

[0004] Therefore, in order to eliminate subjectivity and variability in judgment when diagnosing voids in concrete structures, a method for analyzing the sound of impact on concrete collected by the concrete has been disclosed, for example, in Patent Document 1.

[0005] Patent Document 1 discloses a method for evaluating the internal (back) state of a concrete structure by measuring the vibration waveform during impact and performing frequency analysis on the vibration waveform. This method allows the technology disclosed in Patent Document 1 to automatically detect the presence or absence of voids in an impacted concrete structure. Patent Document 1 focuses on the property that when voids occur in a concrete structure, a sharp peak frequency appears in the frequency analysis result of the impact sound. The technology disclosed in Patent Document 1 utilizes this property to evaluate voids in a concrete structure by performing measurements at adjacent measurement points and evaluating the presence of voids at locations where a sharp peak frequency at a certain measurement point gradually broadens as the measurement point shifts. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-005667 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the technology disclosed in Patent Document 1 had a problem in that it was difficult to establish clear evaluation criteria or indicators regarding the extent to which changes in the sharpness of the peak frequency represent the state of voids in the concrete structure. Furthermore, even when voids were evaluated as being present in the concrete structure, there was a problem in that this result could not be confirmed based on reliable criteria.

[0008] The present invention was devised in view of the above-mentioned problems. Its objective is to provide a concrete structure void evaluation system and program that can automatically and accurately evaluate the voids in a concrete structure by evaluating the voids in the concrete structure based on a reference signal including a first impact sound and an evaluation signal including a second impact sound. [Means for solving the problem]

[0009] The void evaluation system for concrete structures according to the first invention is characterized by comprising: a reference signal acquisition means for acquiring a reference signal including a first impact sound of a concrete structure; an evaluation signal acquisition means for acquiring an evaluation signal including a second impact sound of a concrete structure that is different from the first impact sound; and a void evaluation means for evaluating the voids of a concrete structure based on the reference signal acquired by the reference signal acquisition means and the evaluation signal acquired by the evaluation signal acquisition means.

[0010] The void evaluation system for concrete structures according to the second invention comprises, in the first invention, a reference data acquisition means for acquiring reference data based on frequency analysis of a reference signal acquired by the reference signal acquisition means, and an evaluation data acquisition means for acquiring evaluation data based on frequency analysis of an evaluation signal acquired by the evaluation signal acquisition means, wherein the void evaluation means evaluates the voids of the concrete structure based on the reference data acquired by the reference data acquisition means and the evaluation data acquired by the evaluation data acquisition means.

[0011] The void evaluation system for concrete structures according to the third invention further comprises a sound collection unit for collecting the second impact sound in the first or second invention, the evaluation signal acquisition means acquires the evaluation signal including the second impact sound collected by the sound collection unit, and acquires position information indicating the position of the sound collection unit at the time the second impact sound was acquired, and the void evaluation means evaluates the voids in the concrete structure relative to the position of the sound collection unit based on the reference signal acquired by the reference signal acquisition means, the evaluation signal acquired by the evaluation signal acquisition means, and the position information.

[0012] The void evaluation system for concrete structures according to the fourth invention is characterized in that, in the third invention, it obtains the degree of abnormality of the concrete structure relative to the position of the sound collection unit based on the reference signal obtained by the reference signal acquisition means, the evaluation signal obtained by the evaluation signal acquisition means, and position information, and evaluates the voids of the concrete structure relative to the position of the sound collection unit based on the degree of abnormality.

[0013] The void evaluation system for concrete structures according to the fifth invention, in the fourth invention, the reference data acquisition means obtains the frequency f1, ..., f from the reference signal acquired by the reference signal acquisition means. n Power spectra x1, ..., x of the reference signal n The evaluation data acquisition means obtains the evaluation signals obtained by the evaluation signal acquisition means, and then extracts the frequencies f1, ..., f n Power spectra of evaluation signals y1,…,y n The void evaluation means obtains the cosine similarity C shown in equation (1), obtains the anomaly degree Z shown in equation (2), and evaluates the voids in the concrete structure relative to the position of the sound collection unit based on the anomaly degree.

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[0014] The void evaluation system for concrete structures according to the sixth invention is characterized in that, in the fourth invention, the void evaluation means acquires the differential value of the abnormality with respect to the position of the sound collection unit and evaluates the voids of the concrete structure based on the differential value.

[0015] The void evaluation system for a concrete structure according to the seventh invention is, in the third invention, characterized in that the reference data acquisition means acquires first peak information regarding the peak of the reference signal acquired by the reference signal acquisition means, the evaluation data acquisition means acquires second peak information regarding the peak of the evaluation signal acquired by the evaluation signal acquisition means, and the void evaluation means evaluates the voids of the concrete structure based on the first peak information acquired by the reference data acquisition means and the second peak information acquired by the evaluation data acquisition means.

[0016] The void evaluation system for a concrete structure according to the eighth invention is, in the seventh invention, characterized in that the void evaluation means evaluates the depth at which voids exist in the concrete structure based on the second peak information acquired by the evaluation data acquisition means.

[0017] The void evaluation system for a concrete structure according to the ninth invention is, in the seventh invention, characterized in that the void evaluation means newly acquires a differential value of the second peak information with respect to the position of the sound collection unit based on the second peak information acquired by the evaluation data acquisition means and the position information indicating the position of the sound collection unit, and evaluates the depth at which voids exist in the concrete structure with respect to the position of the sound collection unit based on the differential value.

[0018] The void evaluation program for a concrete structure according to the tenth invention causes a computer to execute a reference signal acquisition step of acquiring a reference signal including a first impact sound of the concrete structure, an evaluation signal acquisition step of acquiring an evaluation signal including a second impact sound of the concrete structure different from the first impact sound, and a void evaluation step of evaluating the voids of the concrete structure based on the reference signal acquired by the reference signal acquisition step and the evaluation signal acquired by the evaluation signal acquisition step.

Advantages of the Invention

[0019] According to the first to ninth inventions, the void evaluation system for concrete structures evaluates the voids in a concrete structure based on a reference signal including a first impact sound and an evaluation signal including a second impact sound of the concrete structure, which is different from the first impact sound. This makes it possible to provide a void evaluation system for concrete structures that can automatically and accurately evaluate the voids in a concrete structure.

[0020] In particular, according to the second invention, the void evaluation system for concrete structures evaluates the voids in the concrete structure based on the results of frequency analysis of the acquired signal. This makes it possible to quantify the signal intensity for each frequency of the signal data, thereby enabling more accurate evaluation of the voids in the concrete.

[0021] In particular, according to the third invention, the void evaluation system for concrete structures acquires a second impact sound to be used as an evaluation signal, as well as location information at the time the second impact sound was acquired, and evaluates the voids in the concrete. This makes it possible to evaluate the locations where voids exist in concrete structures.

[0022] In particular, according to the fourth invention, the concrete structure void evaluation system calculates the degree of abnormality of the concrete structure from reference data based on a reference signal and evaluation data based on an evaluation signal, and evaluates the voids in the concrete. This makes it possible to evaluate the voids in the concrete based on the quantitative difference between the reference data and the evaluation data.

[0023] In particular, according to the fifth invention, the void evaluation system for concrete structures calculates the cosine similarity shown in equation (1) and the anomaly degree Z shown in equation (2) based on the power spectrum of the reference signal and the power spectrum of the evaluation signal, and evaluates the voids in the concrete structure. This makes it possible to evaluate the voids in the concrete based on the quantitative difference between the reference data and the evaluation data.

[0024] In particular, according to the sixth invention, the void evaluation system for concrete structures evaluates the voids in the concrete structure based on the differential value of the degree of abnormality with respect to the position of the sound collection unit that collected the second impact sound. This makes it possible to evaluate the location and depth of voids in concrete in detail.

[0025] In particular, according to the seventh invention, the void evaluation system for concrete structures evaluates the voids in a concrete structure based on first peak information relating to the peak of a reference signal and second peak information relating to the peak of an evaluation signal. This makes it possible to quantitatively evaluate the voids in concrete.

[0026] In particular, according to the eighth invention, the void evaluation system for concrete structures evaluates voids in concrete structures based on second peak information relating to the peak of the evaluation signal. This makes it possible to evaluate in detail the depth to which voids exist in the concrete.

[0027] In particular, according to the ninth invention, the void evaluation system for concrete structures evaluates voids in concrete structures based on the differential value of the second peak information with respect to the position of the sound collection unit. This makes it possible to evaluate in detail the location and depth of voids in the concrete.

[0028] According to the tenth invention, the void evaluation program for concrete structures evaluates the voids in a concrete structure based on a reference signal including a first impact sound and an evaluation signal including a second impact sound of the concrete structure, which is different from the first impact sound. This makes it possible to provide a void evaluation program for concrete structures that can automatically and accurately evaluate the voids in a concrete structure. [Brief explanation of the drawing]

[0029] [Figure 1] Figure 1 shows the overall configuration of the void evaluation system for concrete structures to which the present invention is applied. [Figure 2] Figure 2 shows an example of a mobile unit and a sound collection unit. [Figure 3] Figure 3(a) shows an example of the configuration of the evaluation device in this embodiment. Figure 3(b) is a schematic diagram showing an example of a specific function of the evaluation device. [Figure 4] Figure 4 shows an example of the processing operation flow of a void evaluation system for concrete structures. [Figure 5] Figure 5(a) shows an example of a reference signal. Figure 5(b) shows an example of the results of frequency analysis of the reference signal. [Figure 6] Figure 6 shows an example of reference data. [Figure 7] Figure 7(a) shows an example of an evaluation signal. Figure 7(b) shows an example of the results of frequency analysis of the evaluation signal. [Figure 8] Figure 8 shows an example of evaluation data. [Figure 9] Figure 9 shows an example of calculating the degree of abnormality of a concrete structure. [Modes for carrying out the invention]

[0030] The void evaluation system for concrete structures to which the present invention is applied will be described in detail below with reference to the drawings.

[0031] Figure 1 shows the overall configuration of the void evaluation system 1 for concrete structures 4 to which the present invention is applied. The void evaluation system 1 evaluates the voids in the concrete structure 4 based on signals including the impact sound of the concrete structure 4. As shown in Figure 1, the void evaluation system 1 comprises a mobile body 6, a sound collection unit 5 attached to the mobile body 6, an evaluation device 2 connected to the sound collection unit 5, and a database 3 connected to the evaluation device 2.

[0032] Figure 2 shows an example of a sound collection unit 5 and a moving body 6. As shown in Figure 2, the moving body 6 includes a rotating tapping ball 61, and the sound collection unit 5 includes a microphone 51 attached to the moving body 6, for example, as shown in Figure 2. The sound collection unit 5 may also include sensors such as a GPS (Global Positioning System) or accelerometer to acquire the position at the time of sound collection. The moving body 6 moves at a constant speed on the concrete structure 4, and the rotating tapping ball 61 may continuously strike the concrete structure 4 as the moving body 6 moves. The microphone 51 may collect the impact sound generated when the concrete structure 4 is struck by the rotating tapping ball 61 and transmit it to the evaluation device 2.

[0033] Figure 3(a) shows an example of the configuration of the evaluation device 2 in this embodiment. The evaluation device 2 includes, for example, a housing 20, a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a storage unit 204, and I / F 205~207, as shown in Figure 3(a). The CPU 201, ROM 202, RAM 203, storage unit 204, and I / F 205~207 are connected by an internal bus 210.

[0034] The CPU 201 controls the entire evaluation device 2. The ROM 202 stores the operating code for the CPU 201. The RAM 203 is a working area used when the CPU 201 is operating. The storage unit 204 stores various types of data. The storage unit 204 can be a data storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), SD card, or miniSD card. For example, the evaluation device 2 may also have a GPU (Graphics Processing Unit), which is not shown in the diagram.

[0035] I / F205 is an interface for sending and receiving various data with the database 3 and the sound collection unit 5, etc. I / F206 is an interface for sending and receiving data with the input unit 208. For example, a keyboard is used as the input unit 208, and users of the evaluation device 2 input various data or control commands for the evaluation device 2 via the input unit 208. I / F207 is an interface for sending and receiving various data with the display unit 209. The display unit 209 outputs various data stored in the storage unit 204, or the processing status of the evaluation device 2, etc. A display is used as the display unit 209, and for example, a touch panel type may be used.

[0036] Figure 3(b) is a schematic diagram showing an example of the specific functions of the evaluation device 2. The evaluation device 2 includes, for example, a reference signal acquisition unit 21, a reference data acquisition unit 22, an evaluation signal acquisition unit 23, an evaluation data acquisition unit 24, and a void evaluation unit 25, as shown in Figure 3(b). The reference signal acquisition unit 21 is connected to the reference data acquisition unit 22, and the reference data acquisition unit 22 is connected to the void evaluation unit 25. The evaluation signal acquisition unit 23 is connected to the evaluation data acquisition unit 24, and the evaluation data acquisition unit 24 is connected to the void evaluation unit 25.

[0037] The reference signal acquisition unit 21 acquires a reference signal including the first impact sound of the concrete structure 4 and transmits it to the reference data acquisition unit 22.

[0038] The reference data acquisition unit 22 acquires reference data based on frequency analysis of the reference signal and transmits it to the gap evaluation unit 25.

[0039] The evaluation signal acquisition unit 23 acquires an evaluation signal that includes a second impact sound of the concrete structure 4, which is different from the first impact sound, and transmits it to the evaluation data acquisition unit 24.

[0040] The evaluation data acquisition unit 24 acquires evaluation data based on frequency analysis of the evaluation signal and transmits it to the gap evaluation unit 25.

[0041] The void evaluation unit 25 evaluates the voids in the concrete structure 4 based on a reference signal and an evaluation signal, or reference data and evaluation data.

[0042] The operation of the void evaluation system 1, which has the configuration described above, will now be explained. Figure 4 is an example of the processing operation flow of the void evaluation system 1 for a concrete structure 4. The detailed processing at each step in Figure 4 will be explained below.

[0043] First, in step S11, the reference signal acquisition unit 21 acquires a reference signal including the first impact sound of the concrete structure 4. The reference signal is a signal used as a reference for evaluation in the evaluation of voids in the concrete structure 4. The first impact sound is the sound obtained when striking a part of the concrete structure 4 that has no voids. Alternatively, the first impact sound may be the sound obtained when striking a part of a concrete structure other than the concrete structure 4 that has been evaluated as having no voids.

[0044] The first impact sound may be the sound produced when a worker strikes the concrete structure 4 and determines that there are no voids. Alternatively, the first impact sound may be the sound produced when a mobile body 6 moves within the area where the worker struck the concrete structure 4 and determined that there were no voids, while a rotating tapping ball 61 continuously strikes the concrete structure 4, and the sound is collected by the microphone 51. Alternatively, the first impact sound may be a sound obtained in advance by striking concrete with the same shape and material as the concrete structure 4 and no voids.

[0045] Figure 5(a) shows an example of a reference signal. The reference signal in Figure 5(a) is an example of the first impact sound when there are no voids in the concrete structure 4. The horizontal axis in Figure 5(a) represents the elapsed time as the mobile body 6 moves on the concrete structure 4. During this time, the rotating tapping ball 61 of the mobile body 6 continuously strikes the concrete structure 4. The vertical axis in Figure 5(a) represents the measured sound pressure of the first impact sound collected by the sound collection unit 5 within the given time.

[0046] Next, in step S12, the reference data acquisition unit 22 acquires reference data to be used for void evaluation. The reference data is data based on the frequency analysis of the reference signal acquired by the reference signal acquisition unit 21. The reference data is used as the evaluation standard in the evaluation of voids in the concrete structure 4.

[0047] For example, the reference data acquisition unit 22 may convert the acquired reference signal into numerical data showing the relationship between frequency and intensity at each frequency by applying an FFT (Fast Fourier Transform). Alternatively, the reference data acquisition unit 22 may apply a Fourier transform to the reference signal to convert it into waveform numerical data showing the relationship between time and frequency, then remove a specific frequency range and apply an inverse Fourier transform to convert it into a signal that retains the specific frequency range. Furthermore, the reference data acquisition unit 22 may convert the acquired reference signal into data showing the relationship between intensity and frequency, such as a power spectrum.

[0048] The reference data acquisition unit 22 performs an FFT on the reference signal to obtain frequencies f1, ..., f n Power spectra x1, ..., x of the reference signal n You may obtain it.

[0049] The reference data acquisition unit 22 may acquire first peak information. The first peak information is the frequency and power spectrum of the peak of the reference signal. Here, the peak is the frequency at which the power spectrum is maximum, and the power spectrum is the signal intensity at each frequency when the signal is frequency-decomposed using FFT or the like. Furthermore, if the reference signal has multiple peaks, the reference data acquisition unit 22 may acquire first peak information for multiple peaks.

[0050] The reference data acquisition unit 22 may apply a wavelet transform to the acquired reference signal to convert it into numerical data that shows the relationship between time and frequency. By applying a wavelet transform, it is possible to retain the time characteristics that would be lost during the Fourier transform. Therefore, by applying a wavelet transform, the data is converted into numerical data that shows the relationship between time and frequency.

[0051] The reference data acquisition unit 22 may convert the power spectrum obtained by Fourier transforming the acquired reference signal into a signal representing the cepstrum by taking the logarithm of its value and then inverse Fourier transforming it. Furthermore, the reference data acquisition unit 22 may extract numerical data representing the spectral envelope, which is a low-order cepstrum, and the spectral fine structure, which is a high-order cepstrum, from the numerical data representing the cepstrum. For example, the numerical data representing the spectral envelope may be extracted by defining the cepstrum order. This cepstrum order can take any value, such as 20 or 100. Furthermore, the coefficients of each cepstrum order may be extracted from the numerical data representing the spectral envelope. In addition, the reference data acquisition unit 22 may convert the acquired reference signal into numerical data representing the formant, which is the peak obtained when the amplitude extracted from a certain time domain is converted into the frequency domain. When the peak frequency bands are numbered from lowest to highest as the first formant, second formant, etc., the numerical data may, for example, show the relationship between the first formant and the second formant, or show the relationship between frequencies. The reference data acquisition unit 22 may also perform an AFTE (Auditory filterbank temporal envelope) transform on the acquired reference signal. The reference data acquisition unit 22 may also perform a short-time Fourier transform on the numerical data acquired as the reference signal.

[0052] The reference data acquisition unit 22 may convert the acquired reference signal into two-dimensional numerical data by frequency analysis. The two-dimensional numerical data may represent a relationship between two of the following: time, amplitude, frequency, intensity, spectrum, cepstrum, formant, etc. Alternatively, the reciprocal of these may be taken.

[0053] Furthermore, the reference data acquisition unit 22 may convert the acquired reference signal into three-dimensional numerical data by, for example, applying a spectrogram. The three-dimensional numerical data may represent, for example, three relationships among time, amplitude, frequency, intensity, spectrum, cepstrum, formant, etc.

[0054] Furthermore, the reference data acquisition unit 22 can display reference signals and numerical data via the display unit 209. The reference data acquisition unit 22 can also store this data in storage and, based on user commands, display this data on the display unit 209 or write this data to a portable memory. This allows the user to detach the portable memory from the reference data acquisition unit 22 and carry it with them. In addition, the reference data acquisition unit 22 can transfer this data to other electronic devices via a public communication network.

[0055] Figure 5(b) shows an example of the results of frequency analysis of a reference signal. Figure 5(b) shows the relationship between time, power spectral intensity, and frequency when the signal in Figure 5(a) is used as the reference signal and an FFT is performed on the reference signal.

[0056] Figure 6 shows an example of reference data. Figure 6 shows an example of reference data obtained by performing an FFT on the reference signal shown in Figure 5(a), as shown in the graph in Figure 5(b). The graph in Figure 6 uses the time-averaged intensity of the power spectrum in Figure 5(b) as the reference data.

[0057] In this invention, the configuration of the reference data acquisition unit 22 is not essential and may be omitted. In this case, the reference signal acquired by the reference signal acquisition unit 21 will be transmitted directly to the gap evaluation unit 25.

[0058] Next, in step S13, the evaluation signal acquisition unit 23 acquires an evaluation signal including a second impact sound of the concrete structure 4. The evaluation signal is used to evaluate the voids in the concrete structure 4 by comparing it with a reference signal or reference data. The second impact sound is the impact sound obtained when striking a part of the concrete structure 4 where the voids have not yet been evaluated.

[0059] The second impact sound may be different from the first impact sound obtained in step S12. The location of the concrete structure 4 that is struck to obtain the second impact sound may be different from the location of the concrete structure 4 that was struck to obtain the first impact sound.

[0060] The second impact sound of the concrete structure 4 may be the impact sound picked up by the microphone 51 of the sound collection unit 5 when the concrete structure 4 is continuously struck by the rotating sound ball 61 of the moving body 6.

[0061] In step S13, the evaluation signal acquisition unit 23 may acquire not only the second impact sound collected by the sound collection unit 5, but also the position information of the sound collection unit 5 at the time the second impact sound was collected. The position information is acquired, for example, by a sensor such as GPS included in the sound collection unit 5, or by calculation based on the initial position of the sound collection unit 5 and the movement speed and time of the moving body 6. Since the sound collection unit 5 moves together with the rotating tapping ball 61 as the moving body 6 moves, the position information of the sound collection unit 5 acquired in step S13 is equivalent to the position information indicating the location where the concrete structure 4 was struck.

[0062] Figure 7(a) shows an example of an evaluation signal. The signal in Figure 7(a) is an example of a second impact sound when there is a void in the concrete structure 4. Similar to Figure 5(a), the horizontal axis in Figure 7(a) represents the time the mobile body 6 moves on the concrete structure 4, during which the rotating impact ball 61 of the mobile body 6 continuously strikes the concrete structure 4. The vertical axis in Figure 7(a) represents the measured sound pressure of the impact sound collected by the sound collection unit 5 within the given time. The area enclosed by the dotted line in Figure 7(a) indicates that, within the time frame, the mobile body 6 is located at a point in the concrete structure 4 where there is a void.

[0063] Next, in step S14, the evaluation data acquisition unit 24 acquires evaluation data to be used for void evaluation. The evaluation data is data based on the frequency analysis of the evaluation signal acquired by the evaluation signal acquisition unit 23. Alternatively, the evaluation data may be data extracted from the results of the frequency analysis of the evaluation signal for evaluating voids in the concrete structure 4 by comparing it with a reference signal or reference data.

[0064] The evaluation data acquisition unit 24 may acquire evaluation data by performing frequency analysis on the evaluation signal in the same manner as the reference data acquisition unit 22 performs frequency analysis on the reference signal.

[0065] The evaluation data acquisition unit 24 performs frequency analysis on the evaluation signal to obtain frequencies f1, ..., f n Power spectra of evaluation signals y1,…,y n You may obtain it.

[0066] The evaluation data acquisition unit 24 may acquire second peak information. The second peak information is the frequency and power spectrum of the peak of the evaluation signal. Furthermore, if the evaluation signal has multiple peaks, the evaluation data acquisition unit 24 may acquire second peak information for multiple peaks.

[0067] FIG. 7(b) is a diagram showing an example of the result of frequency analysis of the evaluation signal. FIG. 7(b) shows the relationship between time, frequency, and power spectrum intensity when the signal in FIG. 7(a) is used as the evaluation signal and frequency analysis is performed on the evaluation signal by FFT. Also, the portion surrounded by the dotted line indicates that the moving body 6 is located at a portion with a gap in the concrete structure 4 during the time within this frame.

[0068] According to the comparison between the result of the frequency analysis in FIG. 5(b) and the result of the frequency analysis in FIG. 7(b), when the impact sound when hitting a location where a gap exists is frequency-analyzed, the power spectrum becomes large at a frequency of 2×10 3 ~3×10 3 Hz.

[0069] The evaluation data acquisition unit 24 acquires evaluation data from the result of the frequency analysis of the evaluation signal. For example, the evaluation data acquisition unit 24 may acquire the frequency and the power spectrum at each time as evaluation data in the result of the frequency analysis in FIG. 7(b). The evaluation data acquisition unit 24 may acquire the result of the frequency analysis of the evaluation signal as it is as evaluation data.

[0070] FIG. 8 is a diagram showing an example of evaluation data. The evaluation data in FIG. 8 is data showing the relationship between frequency and power spectrum when a certain time within the time surrounded by the dotted line in FIG. 7(b) is selected. That is, the evaluation data in FIG. 8 is data showing the relationship between the frequency and the power spectrum of the evaluation signal acquired when the moving body 6 is located at a portion with a gap in the concrete structure 4. Also, FIG. 8 shows the reference data in FIG. 6 together in the figure.

[0071] Note that the configuration of this evaluation data acquisition unit 24 is not essential in the present invention and may be omitted. In this case, the evaluation signal acquired by the evaluation signal acquisition unit 23 is directly transmitted to the gap evaluation unit 25.

[0072] Next, in step S15, the void evaluation unit 25 calculates the degree of abnormality of the concrete structure 4 based on the reference data and the evaluation data. The degree of abnormality quantifies the difference between the reference data and the evaluation data. By using the degree of abnormality, it becomes possible to quantify the possibility of voids existing in the concrete.

[0073] For example, the void evaluation unit 25 may obtain the average of the difference in power spectra between the reference data and the evaluation data shown in Figure 8 at each frequency as the anomaly score.

[0074] For example, the air gap evaluation unit 25 uses the frequencies f1, ..., f acquired in step S12. n Power spectra x1, ..., x of the reference signal n And the frequencies f1, ..., f obtained in step S14 n Power spectra of evaluation signals y1,…,y n Therefore, based on the cosine similarity C shown in equation (1), the anomaly score Z shown in equation (2) may be obtained.

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[0075] For example, the void evaluation unit 25 may acquire data showing the relationship between frequency and power spectrum for each time period in which the evaluation signal was measured, based on the results of the frequency analysis of the evaluation signal in Figure 7(b), as evaluation data. This makes it possible to obtain the degree of abnormality at each time period from the reference data and the evaluation data at each time period.

[0076] The void evaluation unit 25 may obtain the degree of abnormality relative to the position of the concrete structure 4 from the position information obtained in step S13 when the second impact sound was collected and the acquired degree of abnormality.

[0077] The void evaluation unit 25 may use the acquired abnormality score to obtain the first or second derivative of the abnormality score with respect to the position of the sound collection unit 5. By calculating the derivative of the abnormality score, it becomes possible to evaluate the position where the abnormality score begins to change as the sound collection unit approaches a location where a void exists. This makes it possible to evaluate the range in which voids occur in the concrete. Furthermore, by calculating the derivative of the abnormality score, it becomes possible to evaluate not only the presence or absence of voids, but also the location and depth of the voids.

[0078] Figure 9 shows an example of the calculation of the abnormality score of the concrete structure 4. The abnormality score in Figure 9 is calculated based on the reference data in Figure 6 and the evaluation data at each time obtained from the frequency analysis results in Figure 7(b). According to Figure 9, the abnormality score is higher when the moving body 6 is located in a location with voids in the concrete structure 4 compared to when the moving body 6 is located in a location without voids.

[0079] The void evaluation unit 25 may evaluate the voids in the concrete structure 4 based on the first peak information acquired in step S12 and the second peak information acquired in step S14. For example, the void evaluation unit 25 may acquire the difference between the frequency of the first peak information and the frequency of the second peak information as an anomaly score and evaluate the voids in the concrete structure 4 based on the acquired anomaly score. For example, the void evaluation unit 25 may acquire the difference between the power spectrum of the first peak information and the power spectrum of the second peak information as an anomaly score and evaluate the voids in the concrete structure 4 based on the acquired anomaly score.

[0080] Furthermore, the void evaluation unit 25 may evaluate the depth to which voids exist in the concrete structure based on the second peak information acquired in step S14. For example, if the evaluation signal has multiple peaks, the difference between the frequency or power spectrum values ​​of different peaks may be used as an index to evaluate the depth to which voids exist.

[0081] Furthermore, the void evaluation unit 25 may obtain a differential value of the second peak information with respect to the position of the sound collection unit based on the second peak information obtained in step S14 and position information indicating the position of the sound collection unit, and evaluate the depth to which voids exist in the concrete structure with respect to the position of the sound collection unit based on the differential value of the second peak information. For example, the differential value with respect to the position of the sound collection unit may be calculated with respect to the frequency information of the second peak information. Alternatively, the differential value with respect to the position of the sound collection unit may be calculated with respect to the power spectrum information of the second peak information. For example, the void evaluation unit 25 may use the change in the differential value of the second peak information with respect to the position of the sound collection unit as an index for evaluating the depth to which voids exist. This makes it possible to evaluate whether the voids in the concrete are progressing toward the surface side of the concrete or toward the back side of the concrete.

[0082] Next, in step S16, the void evaluation unit 25 evaluates the voids in the concrete structure 4 based on the degree of abnormality calculated in step S15. For example, the void evaluation unit 25 may evaluate that voids exist if the calculated degree of abnormality is greater than a preset threshold.

[0083] Furthermore, the void evaluation unit 25 may evaluate the location and depth of voids from an evaluation signal or evaluation data based on an evaluation signal, without using a reference signal and reference data. For example, the void evaluation unit 25 may evaluate the location and depth of voids in the concrete structure 4 based on the difference in frequencies at multiple peaks of the evaluation data.

[0084] If there are no voids in the concrete structure 4, the signal obtained as an evaluation signal by striking with the rotary tapping ball 61 is a signal that includes the sound produced by the vibration of the rotary tapping ball due to the striking and the sound produced by the vibration of the concrete structure. In this case, the spectral characteristics of the evaluation signal will show the sound characteristics due to the vibration of the tapping ball as the main characteristic. Here, spectral characteristics refer to the characteristics of the signal's frequency and intensity, and are, for example, the evaluation data shown by the dotted line in Figure 8.

[0085] When voids exist in the concrete structure 4, the signal obtained as an evaluation signal includes the sound produced by the vibration of the rotary tapping ball 61 due to impact, and the sound produced by the vibration of the concrete structure 4. In this case, compared to the case where no voids exist, the spectral characteristics of the evaluation signal will show not only the sound characteristics from the vibration of the rotary tapping ball 61, but also the sound characteristics from the vibration of the defect in the concrete structure 4, including the voids. Therefore, the spectral characteristics of the evaluation signal will reflect the characteristics such as the location and depth of the voids within the concrete structure.

[0086] For example, the void evaluation unit 25 may evaluate the location and depth of voids in the concrete structure 4 based on the spectral characteristics of the evaluation signal or information about the peaks of the spectral characteristics of the evaluation signal obtained by frequency analysis of the evaluation signal. For example, the location and depth of voids in the concrete structure 4 may be evaluated from the sound characteristics due to vibration of the defect in the concrete structure 4, which are included in the spectral characteristics of the evaluation signal. Also, if the spectral characteristics of the evaluation signal do not include the sound characteristics due to vibration of the defect in the concrete structure 4, it may be evaluated that there are no voids in the concrete structure 4.

[0087] For example, the void evaluation unit 25 may acquire characteristics related to sound caused by the vibration of the rotary tapping ball 61 based on characteristics that commonly appear in the spectral characteristics of evaluation signals acquired at multiple locations. For example, if characteristics other than those related to sound caused by the vibration of the rotary tapping ball 61 appear in the spectral characteristics of the evaluation signal, the void evaluation unit 25 may consider such spectral characteristics as characteristics related to sound caused by vibration of a defect in the concrete structure 4 and evaluate that voids exist in the concrete structure 4.

[0088] Alternatively, the void evaluation unit 25 may acquire the vibration of the concrete structure 4 as an evaluation signal based on the impact elastic wave method and evaluate the voids.

[0089] For example, if there are no voids in the concrete structure 4, the signal obtained as an evaluation signal will include a signal resulting from the reflection of elastic waves generated by the impact at the back end of the concrete structure 4. In this case, the signal related to the reflected elastic waves will have spectral characteristics corresponding to the thickness of the concrete structure 4.

[0090] For example, if voids exist in the concrete structure 4, the signal obtained as an evaluation signal will include not only the signal resulting from the reflection of elastic waves generated by the impact at the back end of the concrete structure 4, but also the signal resulting from the reflection of elastic waves generated by the impact at locations where voids exist inside the concrete structure 4. In this case, the signal obtained as an evaluation signal will have spectral characteristics corresponding to the thickness of the concrete structure 4 and the depth of the voids present inside the concrete structure 4.

[0091] The void evaluation unit 25 may obtain the depth of voids inside the concrete structure 4 based on information regarding the spectral characteristics of the evaluation signal or the peaks of the spectral characteristics of the evaluation signal obtained from the frequency analysis of the evaluation signal using the impact elastic wave method. For example, the void evaluation unit 25 may determine the power spectrum of elastic waves reflected from the end of the concrete structure 4 by comparing the peaks of the reference data shown in Figure 8 with the peaks of the evaluation data.

[0092] For example, the location and depth of voids within the concrete structure 4 may be evaluated by calculating the difference in frequency or power spectrum between different peaks in the evaluation signal. If there are voids in the concrete structure 4, the second impact sound will include signals resulting from elastic waves reflected from the edges of the concrete structure 4 and signals resulting from elastic waves reflected at locations where voids exist within the concrete structure 4. Furthermore, since the characteristics of the signals resulting from elastic waves reflected at locations where voids exist differ depending on the depth of the void, the depth of the void can be evaluated based on the difference in frequency or power spectrum of multiple peaks included in the evaluation data.

[0093] For example, when the depth of a void inside a concrete structure 4 is obtained, if the obtained depth corresponds to the thickness of the concrete structure 4, it may be concluded that there is no void inside the concrete structure 4.

[0094] The above steps complete the operation of the void evaluation system 1 for concrete structure 4 to which the embodiment of the present invention is applied. In the above steps, the void evaluation system 1 for concrete structure 4 evaluates the voids in the concrete structure based on a reference signal including a first impact sound and an evaluation signal including a second impact sound of the concrete structure, which is different from the first impact sound. This makes it possible to automatically and accurately evaluate the voids in the concrete structure.

[0095] While embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0096] 1: Void Evaluation System 2: Evaluation device 3: Database 4: Concrete structures 5: Sound collection section 6: Mobile 21: Reference signal acquisition section 22: Data acquisition unit for reference 23: Evaluation signal acquisition unit 24: Data acquisition unit for evaluation 25: Void Evaluation Section 51: Microphone 61: Rotary percussion ball 20: Cabinet 201:CPU 202 :ROM 203: RAM 204: Preservation Department 205 :I / F 206 :I / F 207 :I / F 208: Input section 209:Display section 210: Internal bus

Claims

1. A reference signal acquisition means for acquiring a reference signal including the first impact sound of a concrete structure, An evaluation signal acquisition means for acquiring an evaluation signal that includes a second impact sound of a concrete structure, which is different from the first impact sound, The system includes a void evaluation means that evaluates the voids in a concrete structure based on a reference signal acquired by the reference signal acquisition means and an evaluation signal acquired by the evaluation signal acquisition means. A void evaluation system for concrete structures characterized by the following.

2. A reference data acquisition means for acquiring reference data based on frequency analysis of the reference signal acquired by the reference signal acquisition means, The system includes an evaluation data acquisition means for acquiring evaluation data based on frequency analysis of the evaluation signal acquired by the evaluation signal acquisition means, The void evaluation means evaluates the voids in a concrete structure based on the reference data acquired by the reference data acquisition means and the evaluation data acquired by the evaluation data acquisition means. A void evaluation system for concrete structures according to claim 1, characterized by the above.

3. The device further includes a sound collection unit for collecting the second impact sound, The evaluation signal acquisition means acquires the evaluation signal including the second impact sound collected by the sound collection unit, and acquires position information indicating the position of the sound collection unit at the time the second impact sound was acquired. The gap evaluation means, based on the reference signal acquired by the reference signal acquisition means, the evaluation signal acquired by the evaluation signal acquisition means, and the position information, To evaluate the voids in the concrete structure relative to the position of the sound collection unit. A void evaluation system for concrete structures according to claim 1 or 2, characterized by the above.

4. The gap evaluation means, based on the reference signal acquired by the reference signal acquisition means, the evaluation signal acquired by the evaluation signal acquisition means, and the position information, The degree of abnormality of the concrete structure relative to the position of the sound collection unit is obtained. Based on the degree of abnormality, evaluate the voids in the concrete structure relative to the position of the sound collection unit. A void evaluation system for concrete structures according to claim 3, characterized by the above.

5. The aforementioned reference data acquisition means obtains the frequency f from the reference signal acquired by the reference signal acquisition means. 1 , ..., f n Power spectrum x of the reference signal 1 , ..., x n Obtain, The evaluation data acquisition means obtains the frequency f from the evaluation signal acquired by the evaluation signal acquisition means. 1 , ..., f n Power spectrum y of the evaluation signal for 1 , ..., y n Obtain, The void evaluation means obtains the degree of abnormality Z shown in equation (2) based on the cosine similarity C shown in equation (1), Based on the degree of abnormality, evaluate the voids in the concrete structure relative to the position of the sound collection unit. A void evaluation system for concrete structures according to claim 4, characterized by the above. [Math 1] [Math 2]

6. The void evaluation means obtains the differential value of the abnormality with respect to the position of the sound collection unit, and evaluates the voids in the concrete structure based on the differential value. A void evaluation system for concrete structures according to claim 4, characterized by the above.

7. The reference data acquisition means acquires first peak information relating to the peak of the reference signal acquired by the reference signal acquisition means, The evaluation data acquisition means acquires second peak information relating to the peak of the evaluation signal acquired by the evaluation signal acquisition means, The void evaluation means evaluates the voids in the concrete structure based on the first peak information acquired by the reference data acquisition means and the second peak information acquired by the evaluation data acquisition means. A void evaluation system for concrete structures according to claim 3, characterized by the above.

8. The void evaluation means evaluates the depth to which voids exist in the concrete structure based on the second peak information acquired by the evaluation data acquisition means. A void evaluation system for concrete structures according to claim 7, characterized by the above.

9. The void evaluation means newly acquires a differential value of the second peak information with respect to the position of the sound collection unit, based on the second peak information acquired by the evaluation data acquisition means and position information indicating the position of the sound collection unit, and evaluates the depth to which voids exist in the concrete structure with respect to the position of the sound collection unit based on the differential value. A void evaluation system for concrete structures according to claim 7, characterized by the above.

10. A reference signal acquisition step involves acquiring a reference signal that includes the first impact sound of a concrete structure, An evaluation signal acquisition step is to acquire an evaluation signal that includes a second impact sound of a concrete structure, which is different from the first impact sound, The computer is instructed to perform a void evaluation step, which evaluates the voids in a concrete structure based on the reference signal acquired in the reference signal acquisition step and the evaluation signal acquired in the evaluation signal acquisition step. A program for evaluating voids in concrete structures, characterized by [specific feature].

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