A concrete defect detection device and a defect size evaluation method
By integrating devices and signal analysis technology, the problems of low accuracy and low efficiency in existing impact echo detection methods for concrete structures have been solved, achieving efficient and accurate defect size assessment and improving the quality and efficiency of concrete structure inspection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INSTITUTE OF TECHNOLOGY (SHENZHEN) (INSTITUTE OF SCIENCE AND TECHNOLOGY INNOVATION HARBIN INSTITUTE OF TECHNOLOGY SHENZHEN)
- Filing Date
- 2025-03-13
- Publication Date
- 2026-05-19
AI Technical Summary
Existing impact echo detection methods for concrete structures suffer from low accuracy, low efficiency, and difficulty in quantitatively assessing defect size, especially in large-area structures where efficient and accurate defect detection is challenging.
A concrete defect detection device integrating a probe aggregator, an impact device aggregator, an electromagnetic excitation device, and a signal acquisition controller is used. The impact hammer is driven by electromagnetic excitation to strike the concrete surface in sequence. The probe receives the echo signal and performs a fast Fourier transform to extract the dominant frequency of the echo. The defect size is then assessed by combining the echo spectrum.
It achieves efficient and accurate concrete defect detection, can quantitatively assess defect length and depth, improves detection efficiency and accuracy, and reduces the difficulty of manual operation and experimental errors.
Smart Images
Figure CN120064452B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of non-destructive testing and dimensional assessment of concrete defects, and in particular to a concrete defect detection device and a defect dimensional assessment method. Background Technology
[0002] Concrete is used extensively in building structures. Due to factors such as concrete shrinkage, insufficient vibration, and rough construction, internal defects may develop in the concrete, affecting the safety and performance of the concrete structure. Therefore, rapid and non-destructive testing of concrete structures on-site provides a solid foundation for ensuring the quality of concrete structures and carrying out subsequent construction procedures. Currently, non-destructive testing methods for concrete structures mainly include impact-echo testing, ultrasonic testing, infrared thermography, and ground-penetrating radar (GPR). Among these, impact-echo testing has become the mainstream method for concrete defect detection due to its advantages such as large detection depth, rapid and simple testing, and low equipment cost. Impact-echo testing generates stress waves by striking the surface of the concrete structure. The probe is fixed to the surface of the concrete structure to detect the echo signal after the stress wave is reflected from the bottom surface of the concrete structure. Because the stress wave undergoes reflection, diffraction, and mode conversion when passing through defects, the frequency components of the detected echo signal change. For common concrete defects such as voids and delamination, this is generally manifested as a decrease in the dominant frequency of the echo. Therefore, by analyzing the dominant frequency of the echo, effective defect identification can be achieved.
[0003] Currently, mainstream impact echo detection devices require operators to use a steel hammer to strike the concrete structure surface to generate stress waves. To ensure testing accuracy, operators must precisely hit each measuring point on the concrete surface with each strike, which is difficult to implement and results in low detection accuracy. Furthermore, for large-area concrete structures such as shear walls, the number of grid points on the test surface may reach hundreds or even thousands. Using traditional single-channel impact echo detectors would be very inefficient. In addition, the impact echo detection results output by current devices are still qualitative, mostly only able to determine the presence of defects, but unable to quantitatively assess the size of concrete defects. Therefore, how to assess the construction quality of concrete structures and improve the accuracy and efficiency of concrete defect detection has become a pressing technical problem to be solved in this field. Summary of the Invention
[0004] The purpose of this application is to provide a concrete defect detection device and a defect size assessment method, which can improve the detection efficiency of internal defects in concrete structures and realize the quantitative assessment of defects in concrete structures.
[0005] To achieve the above objectives, this application provides the following solution:
[0006] In a first aspect, this application provides a concrete defect detection device, which includes a probe collector, an impact device collector, an electromagnetic excitation device, and a signal acquisition controller.
[0007] The signal acquisition controller is connected to the probe assembly, the impact device assembly, and the electromagnetic excitation device, respectively; the electromagnetic excitation device is also connected to the impact device assembly.
[0008] The electromagnetic excitation device is used to electromagnetically excite the impact device assembly to drive the impact device assembly to strike the surface of the concrete structure to be tested.
[0009] The impact device assembly includes several impact hammers arranged in a uniform sequence. Each impact hammer is positioned directly above the surface of the concrete structure to be tested. Each impact hammer is released sequentially under the electromagnetic excitation of the electromagnetic excitation device to strike each measuring point on the surface of the concrete structure to be tested, thereby generating stress wave signals at each measuring point.
[0010] The probe aggregator includes a plurality of probes arranged in a uniform manner. Each probe is positioned directly above the surface of the concrete structure to be tested. Each probe corresponds to an impact hammer. Each probe is used to receive echo signals reflected from the bottom surface of the concrete structure to be tested or from internal defects of the concrete structure to be tested at each measuring point.
[0011] The signal acquisition controller is used to acquire the echo signals received by each of the probes, and to perform a fast Fourier transform on each of the echo signals to obtain multiple signal spectra and echo spectrum diagrams. The controller also extracts the dominant echo frequency from each of the signal spectra, determines whether there is a defect at the corresponding measurement point based on the dominant echo frequency, and estimates the defect size based on the dominant echo frequency and defect characteristic frequency in the echo spectrum diagram for the defect location. The defect size includes the defect length and defect depth.
[0012] Optionally, the surface of the concrete structure to be tested is provided with grid lines, the grid lines including a plurality of first grid lines and a plurality of second grid lines that are perpendicular to each other, and each measuring point is respectively set at the intersection of the first grid lines and the second grid lines.
[0013] Optionally, the probe is a straight probe, which is in close contact with the surface of the concrete structure to be tested.
[0014] Optionally, the probe is an air-coupled microphone, which does not contact the surface of the concrete structure to be tested.
[0015] Optionally, the concrete defect detection device further includes a display screen connected to the signal acquisition controller. The display screen is used to display the echo spectrum, the defect location, and the defect size in real time.
[0016] Secondly, this application provides a method for evaluating the size of concrete defects, the method comprising the following steps:
[0017] Obtain a detection instruction; the detection instruction is an instruction to detect the location and size of defects in the concrete structure to be tested; the defect size includes the defect length and the defect depth;
[0018] According to the detection instruction, a detection device is used to detect the concrete structure to be tested, and the location and size of the defect in the concrete structure to be tested are obtained; the detection device is the concrete defect detection device described in the first aspect.
[0019] Optionally, before the step of using a detection device to detect the concrete structure to be tested according to the detection instruction to obtain the location and size of the defect in the concrete structure to be tested, the concrete defect size assessment method further includes:
[0020] The surface of the concrete structure to be tested is cleaned and leveled to obtain the pretreated concrete structure to be tested.
[0021] A grid line is drawn on the pretreated concrete structure surface to be tested; the grid line includes several first grid lines and several second grid lines that are perpendicular to each other, and each measuring point is set at the intersection of the first grid line and the second grid line.
[0022] Optionally, according to the detection instruction, a detection device is used to detect the concrete structure to be tested, and the location and size of the defect in the concrete structure to be tested are obtained, specifically including:
[0023] Echo signals were collected at various measuring points of the concrete structure under test.
[0024] Perform a Fast Fourier Transform on each of the echo signals to obtain multiple signal spectra and echo spectrum diagrams;
[0025] The echo frequencies are extracted from the spectrum of each signal to obtain multiple echo frequencies;
[0026] Determine whether there is a defect at the corresponding measurement point based on the main frequency of each echo.
[0027] Based on the dominant echo frequency and the characteristic frequency of the defect in the echo spectrum, the size of the defect is estimated for the defect location.
[0028] Optionally, the presence of a defect at a corresponding measurement point is determined based on the dominant echo frequency of each echo; for the defect location, the defect size is estimated based on the dominant echo frequency and the defect characteristic frequency in the echo spectrum, specifically including the following steps:
[0029] Based on the echo frequency value corresponding to each measuring point, determine whether there is a defect at the corresponding measuring point and obtain the first judgment result;
[0030] If the first judgment result is negative, no operation is performed;
[0031] When the first judgment result is yes, the measurement point location corresponding to the abnormal echo dominant frequency value is taken as the defect location, and the defect size is calculated using the following formula based on the echo dominant frequency and defect characteristic frequency in the echo spectrum:
[0032]
[0033] Among them, f d β represents the characteristic frequency of defects, C represents the shape factor of the concrete structure, and C represents the characteristic frequency of defects. p The apparent velocity of the concrete structure is represented by d, and the defect depth is represented by f. T-move f represents the dominant frequency of the echo measured in the defect area. T The dominant frequency of the echo measured in the intact concrete area is given by H, where H is the thickness of the concrete structure, a is the distance between the impact point and the detection point, L1 represents the propagation length of the stress wave through the defect, L represents the length of the defect, and L0 represents the propagation length of the stress wave in the intact concrete area.
[0034] According to the specific embodiments provided in this application, the following technical effects are disclosed:
[0035] This application provides a concrete defect detection device and a defect size assessment method. It integrates a probe aggregator, an impact device aggregator, an electromagnetic excitation device, and a signal acquisition controller. The electromagnetic excitation device electromagnetically excites the impact device aggregator, causing multiple impact hammers integrated within it to be released sequentially. These hammers strike various measuring points on the surface of the concrete structure under test, generating stress wave signals at each point. The probes integrated within the probe aggregator, arranged evenly in sequence, receive the echo signals from each measuring point. These echo signals are reflections from the bottom surface of the concrete structure or from internal defects during stress wave transmission. Therefore, after acquiring the echo signals from each measuring point using the probes in the probe aggregator, the signal acquisition controller analyzes these echo signals (including Fast Fourier Transform, echo frequency extraction, and echo spectrum plotting) to determine the presence of defects at each measuring point and to identify the location, length, and depth of the defects.
[0036] Compared to traditional impact-echo testing devices and single-channel impact-echo detectors that rely on manual tapping, this application eliminates the need for manual tapping, ensuring each tap precisely hits the measuring point. This reduces implementation difficulty, labor intensity, and testing efficiency, effectively improving the detection efficiency of concrete defects. Furthermore, by using impact hammers in the impact device's assembly to strike each measuring point, this mechanical impact method replaces manual tapping, accurately generating stress wave signals for each measuring point and enabling effective detection. Since the entire impact process is unmanned, the energy and waveform of the generated stress waves are guaranteed to be consistent, effectively improving the detection accuracy of concrete defects. It can also accurately quantify defect dimensions such as length and depth, enhancing the detection efficiency of internal defects in concrete structures and enabling quantitative assessment of concrete structural defects. This provides a solid foundation for ensuring the quality of concrete structures and carrying out subsequent construction procedures. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0038] Figure 1 This is a structural schematic diagram of a concrete defect detection device provided in an embodiment of this application.
[0039] Figure 2This is a schematic diagram illustrating the detection principle of a concrete defect detection device provided in an embodiment of this application.
[0040] Figure 3 This is a schematic diagram of the stress wave propagation process through a concrete defect, provided as an embodiment of this application.
[0041] Figure 4 This is a flowchart illustrating a method for evaluating the size of concrete defects, provided in one embodiment of this application.
[0042] Figure 5 This is a schematic diagram illustrating the complete implementation process of a concrete defect size assessment method provided in an embodiment of this application.
[0043] Figure label:
[0044] 1—Probe assembly, 2—Probe, 3—Impact hammer, 4—Electromagnetic excitation device, 5—Impact device assembly, 6—Connecting wire, 7—Signal acquisition controller, 8—Display screen, 9—Concrete structure, 10—Grid line, 11—Concrete slab, 12—Void defect, 13—Impact point, 14—Detection point, 15—Concrete structure thickness, 16—Defect depth, 17—Defect length, 18—Distance between impact point and detection point, 19—Stress wave propagation path through the defect, 20—Stress wave propagation path within the intact concrete area. Detailed Implementation
[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0046] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0047] like Figure 1 As shown in the figure, this embodiment proposes a concrete defect detection device, which mainly includes a probe collector 1, an electromagnetic excitation device 4, an impact device collector 5, a signal acquisition controller 7, and a display screen 8.
[0048] The signal acquisition controller 7 is connected to the probe collector 1, the impact device collector 5, and the electromagnetic excitation device 4. The electromagnetic excitation device 4 is also connected to the impact device collector 5. The display screen 8 is connected to the signal acquisition controller 7.
[0049] In this embodiment, the electromagnetic excitation device 4 is used to electromagnetically excite the impact device assembly 5 to drive the impact device assembly 5 to strike the surface of the concrete structure to be tested.
[0050] In this embodiment, the impact device collector 5 includes a plurality of impact hammers 3 arranged in a uniform manner. Each impact hammer 3 is positioned directly above the surface of the concrete structure to be tested. Each impact hammer 3 is released sequentially under the electromagnetic excitation of the electromagnetic excitation device 4, striking each measuring point on the surface of the concrete structure to be tested in sequence, thereby generating stress wave signals at each measuring point in sequence.
[0051] In this embodiment, the probe aggregator 1 includes a plurality of probes 2 arranged in a uniform manner. Each probe 2 is positioned directly above the surface of the concrete structure to be tested. Each probe 2 corresponds to an impact hammer 3. Each probe 2 is used to receive echo signals reflected from the bottom surface of the concrete structure to be tested or from internal defects of the concrete structure to be tested at each measuring point.
[0052] In this embodiment, probe 2 can be a straight probe 2, which is in close contact with the surface of the concrete structure to be tested. Alternatively, probe 2 can also be an air-coupled microphone, which is not in contact with the surface of the concrete structure to be tested.
[0053] In this embodiment, the signal acquisition controller 7 is used to acquire the echo signals received by each of the probes 2, and perform Fast Fourier Transform (FFT) on each of the echo signals to obtain multiple signal spectra, thereby generating an echo spectrum diagram. The controller also extracts the echo main frequency from each of the signal spectra, determines whether there is a defect at the corresponding measurement point based on the echo main frequency, thereby identifying the defect location, and estimates the defect size based on the echo main frequency and defect characteristic frequency in the echo spectrum diagram for the defect location. The defect size includes the defect length 17 and the defect depth 16.
[0054] In this embodiment, the surface of the concrete structure to be tested is provided with grid lines 10. The grid lines 10 include several first grid lines 10 and several second grid lines 10 that are perpendicular to each other. Each measuring point is set at the intersection of the first grid lines 10 and the second grid lines 10. The distance between two adjacent grid lines 10, the distance between two adjacent impact hammers 3, and the distance between two adjacent probes 2 can all be set to 5 cm, or other values can be used. The density can be adjusted according to the specific situation. For example, for the rapid detection of large-volume concrete structures, the grid line spacing can be increased to reduce the number of measuring points (i.e., grid points); for the case where accurate judgment of concrete defects is required, the grid line spacing can be decreased to increase the number of measuring points.
[0055] In this embodiment, the display screen 8 is used to display echo spectrum, defect location and defect size in real time, thereby realizing the visualization of detection data.
[0056] As an optional implementation, all the impact hammers 3 in the impact device collector 5 are arranged uniformly on the same straight line, and all the probes 2 in the probe collector 1 are also arranged uniformly on the same straight line. This straight line can be a first grid line 10 or a second grid line 10, thereby realizing a line scanning detection method. Along the length or width of the concrete structure to be tested, the impact hammers 3 in the impact device collector 5 and the probes 2 in the probe collector 1 are arranged in a specific way to perform line scanning detection on each measuring point on each first grid line 10 or second grid line 10.
[0057] As an optional implementation, the concrete defect detection device can also be equipped with a moving device, which can be connected to the signal acquisition controller 7. Under the control of the signal acquisition controller 7, the moving device carries the probe collector 1, the impact device collector 5 and the electromagnetic excitation device 4 to move automatically, thereby realizing automated line scanning detection.
[0058] like Figure 1 As shown, this embodiment integrates the probe assembly 1, the impact device assembly 5, and the electromagnetic excitation device 4 to construct a single-direction online scanning concrete defect detection device, enabling rapid detection of impact echoes from multiple measuring points. The concrete defect detection device includes components such as the probe assembly 1, probes 2, an impact hammer 3, an electromagnetic excitation device 4, the impact device assembly 5, connecting wires 6, a signal acquisition controller 7, a display screen 8, concrete, and grid lines 10. Multiple probes 2 are arranged sequentially and integrated into the probe assembly 1. The distance between two adjacent probes 2 is set to be equal to the spacing of the grid lines 10 on the surface of the concrete structure 9, generally around 5 cm. The spacing between two adjacent probes 2 is adjustable within a certain range to meet different grid division requirements.
[0059] In this embodiment, probe 2 is detachable and replaceable. The center frequency of probe 2 reflects the measurable stress wave frequency range of probe 2. Stress wave signals near the center frequency can be captured with high fidelity. Therefore, probes 2 with different center frequencies need to be selected according to the depth of the concrete structure 9. Generally, for thicker concrete structures 9, probes 2 with lower center frequencies should be selected.
[0060] In this embodiment, probe 2 is a straight probe 2, which only receives stress waves reflected from the bottom surface or defects of the concrete. In practical applications, probe 2 needs to be in close contact with the surface of the concrete structure 9 to improve the quality of the received echo signal.
[0061] In this embodiment, an air-coupled microphone can also be used to replace the straight probe 2 to achieve non-contact stress wave measurement, reduce the influence of the surface condition of the concrete structure 9 on the echo signal, and improve the detection accuracy.
[0062] In this embodiment, the probe 2 is essentially a piezoelectric transducer. The echo of the stress wave signal will cause the piezoelectric crystal to vibrate, thus generating an electrical signal by the positive piezoelectric effect. Multiple electrical signals collected by the probe 2 are input into the corresponding multi-channel of the signal acquisition controller 7 through the connecting wire 6.
[0063] In this embodiment, corresponding to the arrangement of probe 2, multiple impact hammers 3 are arranged sequentially and integrated into the impact device collector 5. The distance between two adjacent impact hammers 3 is set to be equal to the spacing of the grid lines 10 on the surface of the concrete structure 9, generally around 5 cm. The spacing between two adjacent impact hammers 3 is adjustable within a certain range. The impact hammers 3 can be replaced with steel hammers of different diameters, ranging from 5 to 25 mm. Each impact hammer 3 is connected to the main body of the impact device collector 5 via a spring, i.e., the two ends of the spring are connected to the main body of the impact device collector 5 and the impact hammer 3, respectively. The impact hammer 3 is driven by an electromagnetic excitation device 4, and the spring releases the impact hammer 3 through the electromagnetic excitation switch of the electromagnetic excitation device 4, thereby striking the surface of the concrete structure 9 to generate a stress wave signal. Since there is no manual intervention in the entire impact process, it can be ensured that the energy and waveform of the generated stress wave are basically consistent, thus effectively improving the detection accuracy.
[0064] In this embodiment, before actual operation, the position of the impact device collector 5 needs to be adjusted so that each impact hammer 3 and its corresponding probe 2 above it are on the same vertical grid line 10, and the distance between them is the spacing between two adjacent grid lines 10. The electromagnetic excitation device 4 is connected to the signal acquisition controller 7 through the connecting wire 6, and the signal acquisition controller 7 controls the impact hammers 3 to be released sequentially from left to right. This line-scanning impact echo device measures and analyzes the propagation of stress wave signals between adjacent measuring points on the vertical grid line 10. Therefore, the impact hammers 3 are released sequentially from left to right to ensure that the corresponding probe 2 above each impact hammer 3 only detects the stress wave signal generated by that impact hammer 3. Since the stress wave enters the interior of the concrete structure 9 from the surface of the concrete structure 9 and is transmitted, the corresponding echo will be reflected back when it reaches the bottom surface of the concrete structure 9 or the defects inside the concrete structure 9, such as Figure 3 The solid single arrow in the diagram represents the stress wave propagation path 19 through the defect, and the dashed single arrow represents the stress wave propagation path 20 within the intact concrete area. By configuring the control software, each probe 2 receives only the echo signal generated by the impact hammer 3 below it. All acquired echo signals undergo Fast Fourier Transform to obtain the signal spectrum, and the maximum frequency value in the signal spectrum is extracted, i.e., the echo dominant frequency (f). IEPlot the echo spectrum of all grid points and display the echo spectrum on display screen 8. IE Anomalies are the locations of potential defects in the concrete structure 9. After completing the impact echo detection of all grid points at a certain height, both the probe collector 1 and the impact device collector 5 are raised by one grid line 10, and impact echo detection is carried out at the corresponding grid points. This process is repeated until the impact echo detection of all grid points on the surface of the entire concrete structure 9 is completed.
[0065] In this embodiment, the echo signal can be understood as the reflected wave of the stress wave signal at the bottom of the concrete structure 9. When there are no defects within the concrete structure 9, the frequency components of the echo measured each time are basically consistent, meaning the dominant frequency of the echo is essentially the same. For example, taking a slab-shaped concrete structure 9 (i.e., concrete slab 11) as an example, the dominant frequency of the echo at a defect-free location is generally around 6kHz when measuring a 20cm thick concrete slab 11. However, when defects exist within the concrete, the stress wave undergoes reflection, diffraction, and mode conversion as it passes through the defects, causing a significant change in the dominant frequency of the echo signal. By analyzing the changes in the dominant frequency, defects in the concrete structure 9 can be accurately identified. Therefore, the abnormal characteristic is a significant change in the dominant frequency. For example, when there is a void, the dominant frequency will generally decrease significantly, such as becoming 5kHz; while when encountering reinforcing bars or steel plates, the dominant frequency will increase significantly, such as becoming 7kHz.
[0066] This embodiment combines a traditional single-channel impact echo detector into an integrated concrete defect detection device. It can measure the echo signals of all grid points along the length direction in a single measurement, achieving line-scan impact echo detection and significantly improving detection efficiency. Furthermore, using an electromagnetically excited impact device instead of manual striking ensures that the energy and waveform of the excited stress waves at each grid point are similar, reducing experimental errors caused by impact source deviations and impact energy differences, and improving the accuracy of defect detection.
[0067] The detection principle of the concrete defect detection device in this embodiment is as follows: Figure 2 As shown. First, based on this concrete defect detection device, according to the echo dominant frequency f... IE To determine if defects exist, generally speaking, defects in concrete structures will cause f IE Decrease. For f IE Anomalies can help predict defect size. The depth of the defect in the concrete structure 9 affects the spectral distribution of the echo. Firstly, striking the surface of the concrete structure 9 with a smaller diameter impact hammer 3 will result in a higher frequency component in the generated echo signal. The defect will cause new characteristic peaks in the high-frequency band of the echo spectrum, expressed as follows:
[0068]
[0069] Among them, fd The defect characteristic frequency f represents the defect characteristic frequency. d The actual frequency is the center frequency of concrete structure 9 above the defect, β represents the shape factor of concrete structure 9, and C p Let f represent the apparent velocity of concrete structure 9, and d represent the defect depth 16. Therefore, according to f d The depth of the defect in the concrete structure 9 can be preliminarily estimated, i.e., the defect depth 16.
[0070] Then, the defect length 17 is estimated. Taking the presence of void defect 12 in concrete structure 9 as an example, the process of evaluating the size of void defect 12 using the concrete defect detection device is described in detail. Figure 3 The diagram illustrates the case where voids exist within the concrete slab 11. For intact concrete, the stress wave propagates along the concrete structure thickness 15 and undergoes a single reflection at the bottom surface of the concrete structure 9. The stress wave propagation length L0 in the intact concrete region is expressed by the following formula:
[0071]
[0072] Where L0 represents the stress wave propagation length of the intact concrete area, H is the thickness of the concrete structure 15, i.e., the thickness of the concrete slab 11, and a is the distance 18 between the impact point and the detection point, i.e., the distance between adjacent intersections of grid lines 10. The impact point 13, the intersection of grid lines 10, and the measuring point refer to the same point, because the impact echo test is conducted at the intersection of grid lines 10, i.e., the measuring point.
[0073] When voids exist within the concrete structure 9, stress waves diffract at the voids, significantly increasing their propagation path. Ignoring the void thickness, the propagation length L1 of the stress wave through the defect is expressed as follows:
[0074]
[0075] Where L1 represents the length of the stress wave propagating through the defect, and L represents the length of the defect (17).
[0076] In this embodiment, a large-diameter impact hammer 3 is used to strike the surface of the concrete structure 9. The voids will cause a decrease in the dominant echo frequency. The dominant echo frequency measured at the void location, i.e., the defect area, is f. T-move The basic principle of measuring structural thickness using shock echo is expressed by the following formula:
[0077]
[0078] Where h represents the thickness of the structure being measured, and f IE This represents the dominant echo frequency. The dominant echo frequency measured in the intact concrete region is f. T The dominant frequency of the echo measured in the defect area is f. T-moveAccording to equations (2), (3), and (4), the following equation can be obtained:
[0079]
[0080] Among them, f T-move f represents the dominant frequency of the echo measured in the defect area. T The dominant frequency of the echo measured in the intact concrete area is given by equation (1). H represents the thickness of the concrete structure (15), a represents the distance between the impact point and the detection point (18), L1 represents the stress wave propagation length through the defect, L represents the defect length (17), L0 represents the stress wave propagation length in the intact concrete area, and d represents the defect depth (16). These values can be calculated using equation (1). Therefore, the value of the defect length (17), i.e., the void length, can be calculated using equation (6) and used as the final size assessment result for the concrete void defect (12).
[0081] It is understood that this embodiment uses voids as an example to illustrate the problem. The method described above is also applicable to other types of defects in concrete, and the length and dimension evaluation results of the corresponding defects can be obtained.
[0082] This embodiment, based on the existing impact echo technology which can only qualitatively detect concrete defects, develops a defect size assessment method with defect depth 16 and defect length 17 by studying the changes in the dominant frequency of the echo and the nature of the derived high-frequency characteristic peaks, thus achieving semi-quantitative defect assessment.
[0083] like Figure 4 As shown, this embodiment provides a method for evaluating the size of concrete defects. This method is actually the method corresponding to the aforementioned concrete defect detection device, and includes the following steps:
[0084] Step 101: Obtain the detection command. The detection command is an instruction to detect the location and size of defects in the concrete structure to be tested; the defect size includes the defect length 17 and the defect depth 16.
[0085] Step 102: According to the detection instruction, use a detection device to detect the concrete structure to be tested, and obtain the location and size of the defect in the concrete structure to be tested. The detection device is the aforementioned concrete defect detection device.
[0086] In this embodiment, before step 102, which uses a detection device to detect the concrete structure to be tested according to the detection instruction, and obtains the location and size of the defect in the concrete structure to be tested, the following steps are also included:
[0087] The surface of the concrete structure to be tested is cleaned and leveled to obtain the pretreated concrete structure to be tested.
[0088] A grid line 10 is drawn on the pretreated concrete structure surface to be tested; the grid line 10 includes several first grid lines and several second grid lines that are perpendicular to each other, and each measuring point is set at the intersection of the first grid line and the second grid line.
[0089] In this embodiment, step 102, according to the detection instruction, uses a detection device to detect the concrete structure to be tested, and obtains the location and size of the defect in the concrete structure to be tested. Specifically, this includes the following steps:
[0090] Step 1021: Collect echo signals at each measuring point of the concrete structure to be tested.
[0091] Step 1022: Perform Fast Fourier Transform on each of the echo signals to obtain multiple signal spectra and echo spectrum diagrams.
[0092] Step 1023: Extract the echo frequency from the spectrum of each signal to obtain multiple echo frequencies.
[0093] Step 1024: Determine whether there is a defect at the corresponding measurement point based on the dominant frequency of each echo, and identify the location of the defect;
[0094] Step 1025: Based on the echo dominant frequency and defect characteristic frequency in the echo spectrum diagram, estimate the defect size for the defect location.
[0095] In this embodiment, steps 1024 and 1025, which identify the defect location and estimate the defect size, specifically include the following steps:
[0096] Based on the echo frequency value corresponding to each measuring point, determine whether there is a defect at the corresponding measuring point to obtain the first judgment result, including the following two cases:
[0097] (1) When the first judgment result is negative, it means that there is no defect at the current measuring point, and no operation is performed at this time.
[0098] (2) When the first judgment result is yes, it indicates that there is a defect at the current measurement point. At this time, the measurement point position corresponding to the abnormal echo main frequency value is taken as the defect position. Based on the echo main frequency and defect characteristic frequency in the echo spectrum, the defect dimensions such as defect depth 16 and defect length 17 are calculated using formula (1)-(6).
[0099] like Figure 5 As shown, the complete evaluation process for concrete defect size assessment methods in actual operation includes the following steps:
[0100] Step S1: Clean and level the test area and draw grid lines 10.
[0101] The surface of the concrete structure to be tested is cleaned and leveled. Grid lines 10 are drawn in the test area. The intersections of the grid lines 10 are the test points for the impact echo.
[0102] Step S2: Fix the concrete defect detection device on the grid line 10 to ensure that the concrete defect detection device is in close contact with the surface of the concrete structure 9.
[0103] The concrete defect detection device is fixed along the length of the grid line 10 of the area to be tested, and the probe 2 is pressed tightly against the surface of the concrete structure 9 to ensure the quality of the received echo signal.
[0104] Step S3: Striking the grid points in sequence generates shock waves, and the corresponding probe 2 receives the echo signals.
[0105] The impact hammer 3 strikes each grid point in sequence, thereby generating shock waves at each measuring point. The echo signal is then received by the corresponding probe 2 and transmitted to the signal acquisition controller 7.
[0106] Step S4: Acquire the echo signal and perform a fast Fourier transform to obtain the signal spectrum and echo spectrum.
[0107] After the echo signal is acquired by the signal acquisition controller 7, a fast Fourier transform is performed on the acquired echo signal to obtain the signal spectrum corresponding to the echo signal, thus forming an echo spectrum diagram.
[0108] Step S5: Extract the echo frequency. Grid points with abnormal frequencies need to be retested.
[0109] Based on the signal spectrum, the maximum frequency value in the signal spectrum is extracted, i.e., the echo frequency. Then, the echo frequencies are compared and analyzed, and grid points with abnormal frequencies are retested to ensure that the echo frequencies of all grid points are normal and valid.
[0110] Step S6: Repeat steps S3-S5 along the moving detection device until all grid points have been traversed.
[0111] By moving the detection device, all grid points within the test area are traversed, ensuring that all grid points have the corresponding echo frequency.
[0112] Step S7: Draw the echo spectrum to achieve defect identification and location.
[0113] Based on the dominant echo frequencies corresponding to all grid points, an echo spectrum diagram is plotted. Regions with abnormal dominant frequencies in the echo spectrum diagram are identified as potential defect areas, thus determining the defect location. Further analysis is then performed... Figure 2 The implementation process and formulas (1)-(6) are used to evaluate and calculate the defect size, and to complete the identification and location of concrete defects.
[0114] The concrete defect detection device and defect size assessment method in this embodiment are applied to a concrete structure 9. The concrete structure 9 may be horizontal, such as a concrete pavement, or vertical, such as a concrete wall. Both the concrete defect detection device and the defect size assessment method are applicable to both horizontal and vertical concrete structures 9. It is only necessary to ensure that the probe 2 is in close contact with the surface of the concrete structure 9 to fully receive the echo signal and ensure the quality of the received echo signal. Effective reception of the echo signal in a vertical state can be achieved by pressing the probe 2 tightly or by adding an acoustic coupling agent between the probe 2 and the surface of the concrete structure 9.
[0115] Compared to traditional impact echo detection devices and single-channel impact echo detectors that rely on manual tapping, this application eliminates the need for manual tapping, ensuring each tap precisely hits the measuring point. This reduces implementation difficulty, labor intensity, and detection efficiency, effectively improving the efficiency of concrete defect detection. Furthermore, by using the impact hammers 3 in the impact device assembly 5 to strike each measuring point, this mechanical impact method replaces manual tapping, accurately generating stress wave signals for each measuring point and enabling effective detection. Since the entire impact process is unmanned, the energy and waveform of the generated stress waves are guaranteed to be consistent, effectively improving the detection accuracy of concrete defects. It also accurately quantifies defect dimensions such as length and depth, allowing for precise assessment of defect dimensions in the concrete structure 9, providing a solid foundation for ensuring the quality of the concrete structure 9 and facilitating subsequent construction procedures.
[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0117] This specification uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A concrete defect detection device, characterized in that, The concrete defect detection device includes a probe collector, an impact device collector, an electromagnetic excitation device, and a signal acquisition controller. The signal acquisition controller is connected to the probe assembly, the impact device assembly, and the electromagnetic excitation device, respectively; the electromagnetic excitation device is also connected to the impact device assembly. The electromagnetic excitation device is used to electromagnetically excite the impact device assembly to drive the impact device assembly to strike the surface of the concrete structure to be tested. The impact device assembly includes several impact hammers arranged in a uniform sequence. Each impact hammer is positioned directly above the surface of the concrete structure to be tested. Each impact hammer is released sequentially under the electromagnetic excitation of the electromagnetic excitation device to strike each measuring point on the surface of the concrete structure to be tested, thereby generating stress wave signals at each measuring point. The probe aggregator includes a plurality of probes arranged in a uniform manner. Each probe is positioned directly above the surface of the concrete structure to be tested. Each probe corresponds to an impact hammer. Each probe is used to receive echo signals reflected from the bottom surface of the concrete structure to be tested or from internal defects of the concrete structure to be tested at each measuring point. The signal acquisition controller is used to acquire the echo signals received by each of the probes, and to perform fast Fourier transform on each of the echo signals to obtain multiple signal spectra and echo spectrum diagrams. The controller also extracts the echo main frequency from each of the signal spectra, determines whether there is a defect at the corresponding measurement point based on the echo main frequency, and estimates the defect size based on the echo main frequency and defect characteristic frequency in the echo spectrum diagram for the defect location. The defect size includes the defect length and the defect depth; wherein, based on the echo dominant frequency value corresponding to each measuring point, it is determined whether a defect exists at the corresponding measuring point, and a first judgment result is obtained; when the first judgment result is negative, no operation is performed; when the first judgment result is positive, the measuring point position corresponding to the abnormal echo dominant frequency value is taken as the defect position, and the defect size is calculated using the following formula based on the echo dominant frequency and the defect characteristic frequency in the echo spectrum: ； ； ； in, f d Indicates the frequency of defect features. β Indicates the shape factor of a concrete structure. C p Indicates the apparent velocity of concrete structures. d Indicates the depth of the defect. f T-move This indicates the dominant frequency of the echo measured in the defect area. f T The dominant frequency of the echo measured in the intact concrete region is given by H, where H is the thickness of the concrete structure and a is the distance between the impact point and the detection point. L 1 represents the length of the stress wave propagating through the defect, and L represents the length of the defect. L 0 represents the length of stress wave propagation in the intact concrete region.
2. The concrete defect detection device according to claim 1, characterized in that, The surface of the concrete structure to be tested is provided with grid lines, which include several first grid lines and several second grid lines that are perpendicular to each other. Each measuring point is set at the intersection of the first grid line and the second grid line.
3. The concrete defect detection device according to claim 1, characterized in that, The probe is a straight probe, which is in close contact with the surface of the concrete structure to be tested.
4. The concrete defect detection device according to claim 1, characterized in that, The probe is an air-coupled microphone, which does not contact the surface of the concrete structure to be tested.
5. The concrete defect detection device according to claim 1, characterized in that, The concrete defect detection device also includes a display screen, which is connected to the signal acquisition controller. The display screen is used to display the echo spectrum, the defect location, and the defect size in real time.
6. A method for evaluating the size of concrete defects, characterized in that, The method for assessing the size of concrete defects includes: Obtain a detection instruction; the detection instruction is an instruction to detect the location and size of defects in the concrete structure to be tested; the defect size includes the defect length and the defect depth; According to the detection instruction, a detection device is used to detect the concrete structure to be tested, and the location and size of the defect in the concrete structure to be tested are obtained; the detection device is the concrete defect detection device according to any one of claims 1-5; According to the detection instruction, a detection device is used to detect the concrete structure to be tested, and the location and size of the defect in the concrete structure to be tested are obtained, specifically including: Echo signals were collected at various measuring points of the concrete structure under test. Perform a Fast Fourier Transform on each of the echo signals to obtain multiple signal spectra and echo spectrum diagrams; The echo frequencies are extracted from the spectrum of each signal to obtain multiple echo frequencies; Based on the dominant echo frequency, determine whether a defect exists at the corresponding measurement point; for the defect location, estimate the defect size based on the dominant echo frequency and defect characteristic frequency in the echo spectrum, specifically including: Based on the echo frequency value corresponding to each measuring point, determine whether there is a defect at the corresponding measuring point and obtain the first judgment result; If the first judgment result is negative, no operation is performed; When the first judgment result is yes, the measurement point location corresponding to the abnormal echo dominant frequency value is taken as the defect location, and the defect size is calculated using the following formula based on the echo dominant frequency and defect characteristic frequency in the echo spectrum: ； ； ； in, f d Indicates the frequency of defect features. β Indicates the shape factor of a concrete structure. C p Indicates the apparent velocity of concrete structures. d Indicates the depth of the defect. f T-move This indicates the dominant frequency of the echo measured in the defect area. f T The dominant frequency of the echo measured in the intact concrete region is given by H, where H is the thickness of the concrete structure and a is the distance between the impact point and the detection point. L 1 represents the length of the stress wave propagating through the defect, and L represents the length of the defect. L 0 represents the length of stress wave propagation in the intact concrete region.
7. The method for evaluating the size of concrete defects according to claim 6, characterized in that, Before the step of using a detection device to detect the concrete structure to be tested according to the detection instruction, and obtaining the location and size of the defect in the concrete structure to be tested, the concrete defect size assessment method further includes: The surface of the concrete structure to be tested is cleaned and leveled to obtain the pretreated concrete structure to be tested. A grid line is drawn on the pretreated concrete structure surface to be tested; the grid line includes several first grid lines and several second grid lines that are perpendicular to each other, and each measuring point is set at the intersection of the first grid line and the second grid line.