An electromagnetic wave detection method and device for defects in the grouting of prestressed ducts of bridges

Abstract

This application relates to the technical field of engineering quality inspection, and discloses an electromagnetic wave detection method and device for defects in grouting of prestressed ducts of bridges. Among them, the ducts are arranged in the bridge concrete structure, and the ducts are filled with grouting material and steel strands. An electromagnetic excitation device is deployed on the surface of the concrete structure to emit electromagnetic pulses with a specified frequency to the detection position of the ducts. The method includes: determining the vibration timing data of the steel strands in the ducts through the vibration signals detected by vibration sensors distributed on the surface of the concrete structure, analyzing the vibration timing data to obtain the detection peak data of the vibration timing data and the detection frequency data of the vibration of the steel strands under the specified frequency electromagnetic pulses, and finally detecting the grouting defects at the detection position according to the detection peak data and / or the detection frequency data to obtain the grouting defect detection result of the detection position. Thus, a method capable of effectively detecting grouting defects in the ducts of bridge prestressed concrete structures is realized.

Description

Technical Field

[0001] The present application relates to the technical field of engineering quality inspection, and particularly to an electromagnetic wave detection method and device for defects in post-tensioned duct grouting of bridges. Background Art

[0002] Long-span concrete bridges generally adopt prestressed structures to resist the self-weight of the bridge and the live load on the upper part. Prestressed steel strands are the main tension bearers in prestressed concrete structures. The construction of prestressed steel strands includes processes such as embedding ducts for cable threading, post-tensioning, anchoring, and duct grouting. Among them, duct grouting plays a role in protecting and filling the prestressed pipelines. Incomplete grouting or even voids will bring serious quality hazards to the long-term use of prestressed steel strands. In related technologies, ultrasonic waves, impact echo method, etc. are often used to identify the fullness of duct grouting. CN106680380A provides a system and its detection method for non-destructively detecting defects in prestressed steel strands by ultrasonic guided waves. This system independently designs a digital signal processing board and adopts a transceiver-in-one detection method. However, it may require professional technicians to operate, and there are detection limitations for steel strands buried in concrete; CN110779959A provides a device and detection method for detecting the compactness of post-tensioned duct grouting, which detects the resistance value through a resistance detector and judges the compactness of grouting at the monitoring point according to the measured resistance value. However, it is affected by environmental factors such as humidity and temperature, and the detection effect for deep or complex-structured ducts is limited. Therefore, a new method for detecting grouting defects needs to be proposed for the construction of post-tensioned duct grouting of bridges. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems in the related technologies to some extent. For this purpose, the present application proposes an electromagnetic wave detection method and device for defects in post-tensioned duct grouting of bridges. The main technical solutions adopted in the present application include:

[0004] In a first aspect, an embodiment of the present application provides an electromagnetic wave detection method for defects in post-tensioned duct grouting of bridges. The duct is arranged in a concrete structure, and the duct contains grouting material and steel strands. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure. The electromagnetic excitation device is used to emit electromagnetic pulses with a specified frequency to the detection position of the duct, and the vibration sensor is used to detect the vibration signal caused by the electromagnetic pulses with the specified frequency to the steel strands at the detection position. The method includes: determining the vibration timing data of the steel strands based on the vibration signal detected by the vibration sensor. Analyzing the vibration timing data to obtain the detection peak data of the vibration timing data and the detection frequency data of the vibration of the steel strands under the electromagnetic pulses with the specified frequency. Performing grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain the grouting defect detection result of the detection position.

[0005] Second aspect, an embodiment of the present application further provides a calibration method for an electromagnetic wave detection device for grouting defects in bridge prestressed ducts. The device includes an electromagnetic excitation device and a vibration sensor. The electromagnetic excitation device and the vibration sensor are deployed on the surface of a concrete model. There is a duct model in the concrete model, and there is grout and a steel strand in the duct model. The electromagnetic excitation device is used to emit a test electromagnetic pulse to a test position of the duct model, and the vibration sensor is used to detect the vibration signal caused by the test electromagnetic pulse to the steel strand at the test position. The calibration method includes: determining the test vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor. Analyzing the test vibration time series data to obtain the test peak data of the test vibration time series data and the test frequency data of the vibration of the steel strand under the test electromagnetic pulse. Constructing the frequency-length relationship data corresponding to the test electromagnetic pulse according to the test peak data and the test frequency data. The frequency-length relationship data is used to describe the corresponding relationship between the test frequency and the length of the grouting defect at the test position.

[0006] Third aspect, an embodiment of the present application provides an electromagnetic wave detection device for grouting defects in bridge prestressed ducts. The duct is arranged in a concrete structure. There is grout and a steel strand in the duct. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure. The electromagnetic excitation device is used to emit a specified-frequency electromagnetic pulse to a detection position of the duct, and the vibration sensor is used to detect the vibration signal caused by the specified-frequency electromagnetic pulse to the steel strand at the detection position. The device includes: a vibration data determination module, configured to determine the vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor. A peak frequency analysis module, configured to analyze the vibration time series data to obtain the detection peak data of the vibration time series data and the detection frequency data of the vibration of the steel strand under the specified-frequency electromagnetic pulse. A grouting defect condition detection module, configured to perform grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain the grouting defect detection result of the detection position.

[0007] Fourth aspect, an embodiment of the present application further provides an electromagnetic wave detection and calibration device for grouting defects in bridge prestressed ducts. The device includes an electromagnetic excitation device and a vibration sensor. The electromagnetic excitation device and the vibration sensor are deployed on the surface of a concrete model. There is a duct model in the concrete model, and there is grout and a steel strand in the duct model. The electromagnetic excitation device is used to emit a test electromagnetic pulse to the test position of the duct model, and the vibration sensor is used to detect the vibration signal caused by the test electromagnetic pulse to the steel strand at the test position. The device includes: a test vibration data determination module, a test frequency determination module, and a frequency-length relationship determination module, where: The test vibration data determination module is used to determine the test vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor. The test frequency determination module is used to analyze the test vibration time series data to obtain the test peak data of the test vibration time series data and the test frequency data of the vibration of the steel strand under the test electromagnetic pulse. The frequency-length relationship determination module is used to construct the frequency-length relationship data corresponding to the test electromagnetic pulse according to the test peak data and the test frequency data. Among them, the frequency-length relationship data is used to describe the corresponding relationship between the test frequency and the length of the grouting defect at the test position.

[0008] Fifth aspect, an embodiment of the present application further provides an electromagnetic wave detection device for grouting defects in bridge prestressed ducts. The device includes a controller, a data acquisition device, an electromagnetic excitation device, and a vibration sensor. The electromagnetic excitation device and the vibration sensor are respectively used to be deployed on the surface of a concrete structure. There is grout and a steel strand in the duct in the concrete structure. The controller is respectively connected to the electromagnetic excitation device and the vibration sensor, and the vibration sensor is connected to the data acquisition device. The electromagnetic excitation device is used to emit a test electromagnetic pulse to the detection position of the duct. The vibration sensor is used to detect the vibration signal caused by the test electromagnetic pulse to the steel strand at the detection position. The data acquisition device is used to determine the vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor. The controller is used to detect the grouting defect at the detection position according to the vibration time series data to obtain the grouting defect detection result of the detection position.

[0009] Sixth aspect, the present application further provides a computer device including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method in any one of the above are implemented.

[0010] Seventh aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in any one of the above are implemented.

[0011] Eighth aspect, the present invention further provides a computer program product, including a computer program. When the computer program is executed by a processor, the steps of the method in any one of the above are implemented.

[0012] In the above embodiments, the vibration timing data of the steel strands in the ducts is determined based on the vibration signals detected by the vibration sensors distributed on the surface of the concrete structure. Further, the detected peak data of the vibration timing data and the detected frequency data of the vibration of the steel strands under the electromagnetic pulses at a specified frequency are obtained by analyzing the vibration timing data. Finally, the grouting defect detection is performed on the detection position according to the detected peak data and / or the detected frequency data, and the grouting defect detection result of the detection position is obtained. Thus, a method capable of effectively detecting the grouting defects in the ducts of the bridge prestressed concrete structure is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0014] Figure 1 It is a flowchart of the electromagnetic wave detection method for the grouting defects in the bridge prestressed ducts according to an embodiment of the present application;

[0015] Figure 2 It is a flowchart of the electromagnetic wave detection method for the grouting defects in the bridge prestressed ducts according to another embodiment of the present application;

[0016] Figure 3 It is a flowchart of the electromagnetic wave detection method for the grouting defects in the bridge prestressed ducts according to another embodiment of the present application;

[0017] Figure 4 It is a flowchart of determining the length of the grouting defect according to an embodiment of the present application;

[0018] Figure 5 It is a flowchart of the calibration method of the electromagnetic wave detection device for the grouting defects in the bridge prestressed ducts according to an embodiment of the present application;

[0019] Figure 6a It is a schematic diagram of the scenario of the electromagnetic wave detection method for the grouting defects in the bridge prestressed ducts according to an embodiment of the present application;

[0020] Figure 6b It is a flowchart of the electromagnetic wave detection method for the grouting defects in the bridge prestressed ducts according to an embodiment of the present application;

[0021] Figure 7 It is a structural block diagram of an electromagnetic wave detection device for the grouting defects in the bridge prestressed ducts according to an embodiment of the present application;

[0022] Figure 8 A structural block diagram of an electromagnetic wave detection and calibration device for grouting defects in bridge prestressed ducts provided according to an embodiment of the present application;

[0023] Figure 9 A structural block diagram of an electromagnetic wave detection device for grouting defects in bridge prestressed ducts provided according to another embodiment of the present application;

[0024] Figure 10 An internal structure diagram of a computer device provided according to an embodiment of the present application. Specific implementation manners

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0026] Prestressed steel strands are the main tensile bearers in prestressed concrete structures. The construction of prestressed steel strands includes processes such as embedding ducts for cable threading, post-tensioning, anchoring, and duct grouting. The specific construction process includes:

[0027] 1. Before concrete pouring, ducts are buried at predetermined positions, and then the steel strands are threaded through these ducts; 2. After the concrete is poured and starts to harden, the steel strands are stretched, just like tightening a bowstring, to apply prestress to the concrete; 3. The stretched steel strands are fixed with anchors to prevent them from rebounding; 4. The ducts are grouted to fix the steel strands in the correct positions and protect the steel strands from corrosion. Among them, duct grouting has a protective and filling effect on prestressed pipelines. Incomplete grouting or even voids will pose serious quality hazards to the long-term use of prestressed steel strands.

[0028] In the related art, there is a lack of relatively effective detection methods. CN115389546A provides a device and method for monitoring the grouting density of prestressed bridge ducts. By using fiber optic monitoring equipment to replace traditional methods such as impact echo method, ultrasonic detection method, and ground penetrating radar method, automatic monitoring is achieved. However, it may require professional equipment and technology for monitoring, and there are certain technical requirements for on-site technicians. CN106680380A provides a system and its detection method for non-destructively detecting defects in prestressed steel strands by ultrasonic guided waves. The system independently designs a digital signal processing board, with low cost and easy maintenance. Adopting a transceiver co-located detection method, the ultrasonic guided wave has small transmission attenuation and can detect at a farther distance, improving the detection efficiency. However, it may require professional technicians to operate, and there may be detection limitations for steel strands buried in concrete. CN110779959A provides a device and detection method for detecting the grouting density of prestressed ducts. The resistance value is detected by a resistance detector, and the grouting density of the monitoring point is judged according to the measured resistance value. The operation is simple and the cost is low. However, it may be affected by environmental factors such as humidity and temperature, and the detection effect for deep or complex structure ducts is limited. Using ultrasonic waves, impact echo method, etc. is more difficult to identify, and the inner wall of the embedded duct causes great interference to the detection. Specifically, because the inner wall of the duct in the prestressed concrete structure is not always flat and smooth, there may be rough areas or curved areas. In this case, when using technologies such as ultrasonic waves or impact echo method for detection, the curved or uneven pipe wall will cause multiple reflections of ultrasonic waves, which may lead to signal distortion and make it difficult to accurately judge. Moreover, the complex geometric shape of the pipeline may complicate the ultrasonic wave path and affect the accuracy of the detection result. In addition, the materials of the ducts in the prestressed concrete structure include metal materials and non-metal materials. If ultrasonic waves or impact echo method and other technologies are used to detect metal materials, the pipe wall of the metal material may scatter the ultrasonic wave energy in multiple directions, reducing the signal focusing degree and detection accuracy; if detecting grouting defects in non-metal material ducts, the penetration of ultrasonic waves or impact echo method and other technologies will be greatly reduced, thus affecting the accuracy and reliability of grouting defect detection. In contrast, if the electromagnetic pulse method is used for grouting defect detection, regardless of the material, because the steel strand has a good response to the electromagnetic pulse, the electromagnetic pulse can generate a force on the steel strand to cause the steel strand to vibrate. Therefore, using the electromagnetic pulse will not be affected by whether the pipeline material is metal and has better applicability in a non-metal environment. In addition, because the electromagnetic pulse technology relies more on the interaction between the electromagnetic field and the steel strand rather than the mechanical propagation of sound waves, the electromagnetic pulse technology has better anti-interference ability to the interference of the geometric shape and internal structure of the pipeline.

[0029] Based on this, according to the embodiments of the present application, an embodiment of a method and device for detecting electromagnetic wave defects in the grouting of bridge prestressed ducts is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0030] In this embodiment, a method for detecting electromagnetic wave defects in the grouting of bridge prestressed ducts is provided. The duct is arranged in a concrete structure, and there is grouting material and steel strands in the duct. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure. The electromagnetic excitation device is used to emit electromagnetic pulses with a specified frequency to the detection position of the duct, and the vibration sensor is used to detect the vibration signal caused by the electromagnetic pulses with the specified frequency on the steel strands at the detection position. Figure 1 It is a flowchart of a method for detecting electromagnetic wave defects in the grouting of bridge prestressed ducts according to the embodiments of the present application, as Figure 1 shown, this process includes the following steps:

[0031] S110. Determine the vibration timing data of the steel strands based on the vibration signals detected by the vibration sensor.

[0032] Among them, the vibration timing data can be the vibration signals recorded in the time series, which can be used to represent the vibration signal data caused by the resonance of the steel strands in the duct under the concrete structure when they feel the electromagnetic pulses with the specified frequency emitted by the electromagnetic excitation device. Exemplarily, the electromagnetic pulse frequency that is most likely to cause the resonance of the steel strands can be taken as the specified frequency of the electromagnetic pulses sent by the electromagnetic excitation device. Specifically, the electromagnetic excitation device emits electromagnetic pulses with a specified frequency to the detection position of the duct, the vibration sensor detects the vibration of the steel strands at the detection position due to the electromagnetic pulses, converts it into an electrical signal, and finally records the time curve of the vibration sensor data at this specified frequency through a data acquisition device, that is, the vibration timing data of the steel strands under the electromagnetic pulses with this specified frequency is obtained.

[0033] S120. Analyze the vibration timing data to obtain the detection peak data of the vibration timing data and the detection frequency data of the vibration of the steel strands under the electromagnetic pulses with the specified frequency.

[0034] Among them, the detected peak data may refer to the maximum amplitude data recorded by a time series of the vibration signal generated by the resonance of the steel strand at the detection position caused by an electromagnetic pulse with a specified frequency. Exemplarily, the maximum amplitude value of the vibration signal can be used as the detected peak data, or the vibration peak curve drawn when the maximum amplitude value changes with time can be used as the detected peak data of the vibration signal. It can be understood that the detected frequency data may refer to the frequency data obtained by analyzing the vibration signal generated by the resonance of the steel strand at the detection position caused by an electromagnetic pulse with a specified frequency.

[0035] Specifically, when the electromagnetic excitation device applies an electromagnetic pulse with a specified frequency to cause the vibration of the steel strand at the detection position, the data acquisition device can record the vibration time series data at the corresponding frequency captured by the vibration sensor. The detected peak data at the detection position can be extracted by analyzing the time curve of these vibration time series data. Further, the detected frequency data of the vibration of the steel strand at the detection position under the electromagnetic pulse with a specified frequency can be obtained by analyzing and processing the detected peak data. Exemplarily, the peak points of the vibration time series data detected at the detection position can be plotted into a detected peak curve in chronological order, where the abscissa can represent time and the ordinate represents the peak value, thus obtaining the detected peak data of the vibration time series data at the detection position. Further, the fast Fourier transform (FFT) or short-time Fourier transform (STFT) is applied to the vibration time series data to analyze the frequency components of the vibration signal, and the process of the amplitude of the frequency components changing with frequency is plotted into a detected frequency curve, which is used as the detected frequency data of the vibration of the steel strand at the detection position under the electromagnetic pulse with a specified frequency. Among them, the abscissa can represent frequency and the ordinate represents amplitude.

[0036] S130. Perform grouting defect detection on the detection position according to the detected peak data and / or the detected frequency data to obtain the grouting defect detection result of the detection position.

[0037] Among them, grouting defect detection is a non-destructive testing technology that can be used to identify and evaluate the fullness of grouting in the ducts inside concrete structures and the length of grouting defects. A value greater than can be used as the length of the grouting defect to represent the distance of the void area where the grouting in the duct is not full. It should be noted that if the grouting in the duct is full, the length of the grouting defect can be regarded as equal to 0. Exemplarily, the detection of whether there are voids or grouting defect phenomena in the bond between the grouting material and the steel strand in the duct can be carried out by analyzing the vibration signal caused by the electromagnetic pulse of a specified frequency at the detection position. Among them, the vibration signal captured by the vibration sensor at the detection position reflects the dynamic vibration response inside the duct, and these dynamic vibration responses are closely related to the fullness of the grouting inside the duct. Exemplarily, when the bond between the grouting material and the steel strand in the duct is good and there are no voids, the fully grouted duct at this time has higher structural stiffness and damping, and will more effectively absorb and dissipate vibration energy or suppress the amplitude of vibration, resulting in a smaller signal amplitude captured by the vibration sensor; similarly, when the bond between the grouting material and the steel strand in the duct is poor and there are voids, the grouting defect area will reduce the structural stiffness and damping, making the vibration easier to spread, thus making the signal amplitude captured by the vibration sensor larger. Therefore, by analyzing whether the detected peak data and / or detected frequency data obtained at the detection position are abnormal under the condition of the electromagnetic pulse of the specified frequency, it is judged whether there is a grouting defect phenomenon at the detection position under the condition of the electromagnetic pulse of the specified frequency, and finally the grouting defect detection result of the duct at the detection position is obtained. If the grouting defect detection result shows that there is a grouting defect phenomenon at the detection position under the condition of the electromagnetic pulse of the specified frequency, the specific length of the grouting defect of the duct at the detection position can also be further determined by analyzing the detected peak data and / or detected frequency data obtained at the detection position.

[0038] Specifically, the duct model in the state of grouting defect can be calibrated for vibration detection in advance. The designated frequency electromagnetic pulse is used to perform calibrated vibration detection on the detection position, and the test peak data and test frequency data measured at the test position under the condition of the designated frequency electromagnetic pulse for this duct model are obtained. Further, based on the analysis of the detected peak data and / or detected frequency data, the test peak data and test frequency data obtained through calibrated vibration detection are respectively identified and compared with the detected peak data and detected frequency data obtained in the actual grouting defect detection. Exemplarily, the test peak data and test frequency data obtained through calibrated vibration detection are used as a reference to identify abnormal detected peak data and / or detected frequency data, so as to determine whether there is a grouting defect at the detection position of the duct under the condition of the designated frequency electromagnetic pulse. If the grouting defect detection indicates that there is a grouting defect at the detection position under the condition of the designated frequency electromagnetic pulse, then further based on the test peak data and test frequency data measured at the test position of the duct model in the state of grouting defect, the corresponding relationship between the test frequency data and the grouting defect length, that is, the frequency-length relationship data, is constructed to determine the specific grouting defect length at the detection position of the duct under the condition of the designated frequency electromagnetic pulse.

[0039] In the above embodiment, the vibration timing data of the steel strand in the duct is determined by the vibration signals detected by the vibration sensors distributed on the surface of the concrete structure. Further, the detected peak data of the vibration timing data and the detected frequency data of the vibration of the steel strand under the designated frequency electromagnetic pulse are obtained by analyzing the vibration timing data. Finally, the grouting defect detection of the detection position is performed according to the detected peak data and / or detected frequency data, and the grouting defect detection result of the detection position is obtained. Thus, a method capable of effectively detecting the grouting defects of the ducts in the prestressed concrete structure is realized.

[0040] In some embodiments, the grouting defect detection of the detection position is performed according to the detected peak data and / or detected frequency data, and the grouting defect detection result of the detection position is obtained, including: when the detected peak data is less than the first calibrated peak data, it is determined that the detection position is in a state of full grouting.

[0041] Among them, the first calibrated peak data can be determined by calibrating the vibration detection of the duct model in the grouting full state using an electromagnetic pulse with a specified frequency. Exemplarily, the specified frequency electromagnetic pulse is used as the test electromagnetic pulse. By applying the test electromagnetic pulse to the steel strand in the duct model in the grouting full state to excite its resonance, the test vibration time series data generated thereby is recorded, which contains the response characteristics of the duct model in the grouting full state. Analyze the test vibration time series data to obtain the test peak data of the test vibration time series data, and this test peak data can be used as the first calibrated peak data. Further, if the detected peak data is less than the first calibrated peak data, it is considered that under the specified frequency electromagnetic pulse, the dynamic vibration response inside the duct at the detected position is less than the dynamic vibration response inside the duct of the duct model in the grouting full state. Based on the bonding characteristics between the grouting material and the steel strand in the duct, when the bonding between the grouting material and the steel strand in the duct is good and there is no gap, at this time, the grouting full duct has higher structural stiffness and damping, and will more effectively absorb and dissipate vibration energy or suppress the amplitude of vibration, resulting in a smaller signal amplitude captured by the vibration sensor. Therefore, if the detected peak data is less than the first calibrated peak data, it can be considered that under the specified frequency electromagnetic pulse, the duct is in the grouting full state at the detected position.

[0042] In the above embodiment, in the case where the detected peak data and the detected frequency data have been obtained, by comparing the first calibrated peak data obtained by pre-using an electromagnetic pulse with a specified frequency to perform vibration detection on the duct model in the grouting full state with the detected peak data, the process of detecting the grouting defect at the detected position of the duct and obtaining the grouting defect detection result at the detected position can be realized under the specified frequency electromagnetic pulse, improving the efficiency of detecting the grouting defect of the duct in the prestressed concrete structure.

[0043] In some embodiments, please refer to the appendix Figure 2 , perform grouting defect detection on the detected position according to the detected peak data and / or the detected frequency data, and obtain the grouting defect detection result at the detected position, including:

[0044] S210. Determine the target frequency range within the frequency range corresponding to the detected frequency data.

[0045] Among them, the detected frequency data can refer to the frequency data obtained by analyzing the vibration signal generated by the resonance of the steel strand at the detected position caused by an electromagnetic pulse with a specified frequency. The target frequency range is a certain frequency range in the detected frequency data where the target vibration frequency for detecting the grouting defect at the detected position of the duct under the specified frequency electromagnetic pulse is located. Exemplarily, a certain interval range where the vibration energy shows abnormality or the detected frequency data has an abnormal peak can be taken as the target frequency range.

[0046] S220. Calculate the mean value according to the target frequency range to obtain the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency.

[0047] Exemplarily, there may be multiple abnormal peaks in the detected frequency data. In this case, it is necessary to calculate the mean value for all target frequency ranges where abnormal peaks appear, and finally obtain a most representative vibration frequency as the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency at the detection position.

[0048] S230. Search in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length at the detection position.

[0049] Among them, a value greater than 0 can be used as the grouting defect length to represent the distance of the cavity area where the grouting in the duct is not full. It should be noted that if the grouting in the duct is full, the grouting defect length can be regarded as equal to 0. The frequency-length relationship data is the corresponding relationship between the test frequency data measured at the test position and the grouting defect length obtained by calibrating the vibration detection of the duct model in the grouting defect state using the electromagnetic pulse of the specified frequency in advance. Exemplarily, the frequency-length relationship data can be a table or database formed by mapping the test frequency data to the grouting defect length, or a polynomial function with the test frequency data as the independent variable and the grouting defect length as the dependent variable. Specifically, using the electromagnetic pulse of the specified frequency as the test electromagnetic pulse, the calibration vibration detection is carried out for the duct models in different grouting defect states, and the corresponding relationship between the test frequency data measured at the test position and the grouting defect length of the duct models in different grouting defect states under the test electromagnetic pulse is obtained, which can be used as the frequency-length relationship data. After determining the frequency-length relationship data under the electromagnetic pulse of the specified frequency, substitute the target vibration frequency into the determined frequency-length relationship data to search for the grouting defect length of the duct at the detection position.

[0050] In the above embodiment, by pre-establishing the corresponding relationship between the test frequency data measured at the test position and the grouting defect length of the duct model in the grouting defect state using the electromagnetic pulse of the specified frequency, the process of detecting the grouting defect at the detection position and obtaining the grouting defect detection result of the duct at the detection position under the electromagnetic pulse of the specified frequency is realized. Through this search method, the quantitative evaluation of the grouting defect length of the internal duct of the concrete structure can be realized, and the grouting defect detection result of the detection position of the duct in the prestressed concrete structure can be obtained more intuitively.

[0051] In some embodiments, please refer to the appendix Figure 3, perform grouting defect detection on the detection position according to the detection peak data and / or detection frequency data, and obtain the grouting defect detection result of the detection position, including:

[0052] S310. When there is an out-of-peak data greater than the second calibrated peak data in the detection peak data, determine the frequency interval corresponding to the out-of-peak data.

[0053] Among them, the second calibrated peak data can be determined by pre-using a specified frequency electromagnetic pulse to perform calibrated vibration detection on the duct model in the grouting defect state. Specifically, use the specified frequency electromagnetic pulse as the test electromagnetic pulse, and perform calibrated vibration detection on the duct models in different grouting defect states to obtain the second calibrated peak data of the duct models in different grouting defect states under different test electromagnetic pulses. It can be understood that if there is an out-of-peak data greater than the second calibrated peak data in the detection peak data, then obtain all the frequency intervals where the detection peak data is greater than the second calibrated peak data as the out-of-peak data.

[0054] S320. Determine the grouting defect length of the detection position according to the frequency interval corresponding to the out-of-peak data and the frequency-length relationship data.

[0055] Among them, a value greater than 0 can be used as the grouting defect length to represent the distance of the cavity area where the grouting in the duct is not full. It should be noted that if the grouting in the duct is full, the grouting defect length can be regarded as equal to 0. The frequency-length relationship data is the corresponding relationship between the test frequency data measured at the test position and the grouting defect length obtained by pre-using a specified frequency electromagnetic pulse to perform calibrated vibration detection on the duct model in the grouting defect state. Exemplarily, the frequency-length relationship data can be a table or database formed by mapping the test frequency data to the grouting defect length, or a polynomial function with the test frequency data as the independent variable and the grouting defect length as the dependent variable. Specifically, use the specified frequency electromagnetic pulse as the test electromagnetic pulse, and perform calibrated vibration detection on the duct models in different grouting defect states. Obtain the corresponding relationship between the test frequency data measured at the test position and the grouting defect length of the duct models in different grouting defect states under the test electromagnetic pulse, and use it as the frequency-length relationship data. Further, determine the corresponding frequency interval according to the out-of-peak data, and take the interval median value in the frequency interval as the target vibration frequency corresponding to the out-of-peak data. After determining the frequency-length relationship data under the specified frequency electromagnetic pulse, substitute the target vibration frequency corresponding to the out-of-peak data into the corresponding frequency-length relationship data for calculation to obtain the grouting defect length of the duct at the detection position.

[0056] In the above embodiments, by comparing the detected peak data with the second calibrated peak data to determine the exceeded peak data, based on the frequency range corresponding to the exceeded peak data, the target vibration frequency corresponding to the exceeded peak data is determined and substituted into the corresponding frequency-length relationship data for calculation to obtain the grouting defect length of the duct at the detection position. Through this calculation method, quantitative evaluation of the grouting defect length of the internal duct of the concrete structure can be realized, and the grouting defect detection result of the detection position of the duct in the prestressed concrete structure can be obtained more quickly.

[0057] In some embodiments, please refer to the appendix Figure 4 , determining the grouting defect length of the detection position according to the frequency range corresponding to the exceeded peak data and the frequency-length relationship data, includes:

[0058] S410. Perform mean calculation according to the frequency range corresponding to the exceeded peak data to obtain the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency.

[0059] Exemplarily, if there are multiple exceeded peak data, it is necessary to perform mean calculation on the frequency ranges where all the exceeded peak data are located, and finally obtain a most representative frequency range as the exceeded peak data of the steel strand vibrating under the electromagnetic pulse of the specified frequency at the detection position. Further, according to the exceeded peak data, its corresponding frequency range is determined, and mean calculation is performed again in the frequency range to obtain the target vibration frequency corresponding to the exceeded peak data, that is, the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency at the detection position.

[0060] S420. Search in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length of the detection position.

[0061] Among them, a value greater than 0 can be used as the grouting defect length to represent the distance of the cavity area where the grouting in the duct is not full. It should be noted that if the grouting in the duct is full, the grouting defect length can be regarded as equal to 0. The frequency-length relationship data is the corresponding relationship between the test frequency data measured at the test position and the grouting defect length obtained by calibrating the vibration detection of the duct model in the grouting defect state by using the electromagnetic pulse of the specified frequency. Specifically, after determining the frequency-length relationship data under the electromagnetic pulse of the specified frequency, the target vibration frequency is substituted into the corresponding frequency-length relationship data for searching to obtain the grouting defect length of the duct at the detection position.

[0062] In the above embodiments, based on the frequency range corresponding to the peak-exceeding data, the target vibration frequency of the strand vibrating under the electromagnetic pulse of the specified frequency at the detection position is determined and substituted into the corresponding frequency-length relationship data for calculation to obtain the grouting defect length of the duct at the detection position. By quantitatively evaluating the grouting defect length of the internal duct of the concrete structure, the grouting defect detection result of the detection position of the duct in the prestressed concrete structure can be obtained more quickly.

[0063] In some embodiments, the frequency-length relationship data is determined in the following manner: Search in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency to obtain the relationship data corresponding to the pulse frequency as the frequency-length relationship data.

[0064] Among them, the pulse frequency of the electromagnetic pulse of the specified frequency is used to represent the pulse frequency that is commonly used or selected depending on the vibration characteristics of the strand during the grouting defect detection process. Exemplarily, the electromagnetic pulse frequency that is most likely to cause the strand to resonate can be taken as the electromagnetic pulse of the specified frequency sent by the electromagnetic excitation device. It can be understood that the pulse frequency of the electromagnetic pulse of the specified frequency can be multiple.

[0065] The relationship data set includes the frequency-length relationship data measured at the test position by pre-calibrating the vibration detection of the duct model in the grouting defect state using multiple test electromagnetic pulses respectively. Specifically, under multiple test electromagnetic pulses, the calibration vibration detection is performed on the duct models in different grouting defect states. The corresponding relationship between the test frequency data measured at the test position and the grouting defect length of the duct models in different grouting defect states under multiple test electromagnetic pulses is obtained and can be used as the relationship data set. Further, when performing grouting defect detection at the detection position, after determining the pulse frequency of the electromagnetic pulse of the specified frequency, search in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency, and find and match the pulse frequency of the electromagnetic pulse of the specified frequency with the test electromagnetic pulse during the calibration vibration detection to determine the frequency-length relationship data at the pulse frequency of the specified frequency.

[0066] In the above embodiments, a relationship data set based on multiple test electromagnetic pulses for duct models in different grouting defect states is established in advance. When performing grouting defect detection at the detection position, after determining the pulse frequency of the electromagnetic pulse of the specified frequency, search in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency, and find and match the pulse frequency of the electromagnetic pulse of the specified frequency with the test electromagnetic pulse during the calibration vibration detection to determine the frequency-length relationship data at the pulse frequency of the specified frequency. When it is necessary to determine the frequency-length relationship data at the specified frequency, it can be directly retrieved and searched in the relationship data set, further improving the efficiency of grouting defect detection for the detection position of the duct.

[0067] In some embodiments, the specified-frequency electromagnetic pulses include a plurality of electromagnetic pulses with different pulse frequencies. The electromagnetic excitation device is configured to use a step-by-step method to emit electromagnetic pulses with different pulse frequencies to the detection position in a gradually increasing manner from small to large.

[0068] In the above embodiments, the electromagnetic excitation device uses a step-by-step method to emit electromagnetic pulses with different pulse frequencies to the detection position by gradually increasing the frequency. On the one hand, it can detect the vibration response of the duct more carefully and improve the detection sensitivity. On the other hand, if a fixed frequency or a jump-type frequency change is used, some key resonance frequencies may be missed. The step-by-step method can ensure that all possible frequency ranges are covered, reduce omissions, and thus improve the accuracy and reliability of effectively detecting the grouting defects in the ducts of prestressed concrete structures.

[0069] The embodiments of this specification also provide a calibration method for an electromagnetic wave detection device for grouting defects in bridge prestressed ducts. The electromagnetic wave detection device for grouting defects in bridge prestressed ducts includes an electromagnetic excitation device and a vibration sensor. The electromagnetic excitation device and the vibration sensor are deployed on the surface of the concrete model. There is a duct model in the concrete model, and there is grouting material and steel strands in the duct model. The electromagnetic excitation device is configured to emit test electromagnetic pulses to the test position of the duct model, and the vibration sensor is configured to detect the vibration signal caused by the test electromagnetic pulses on the steel strands at the test position. Please refer to the appendix Figure 5 , and the method includes the following steps:

[0070] S510. Determine the test vibration timing data of the steel strands based on the vibration signals detected by the vibration sensor.

[0071] Similarly, the test vibration timing data can also be the vibration signals recorded in the time series, which can be used to represent the vibration signal data caused by the resonance of the steel strands in the duct model under the concrete model structure when they sense the test electromagnetic pulses emitted by the electromagnetic excitation device. Exemplarily, the electromagnetic pulse frequency that is most likely to cause the resonance of the steel strands can be taken as the test electromagnetic pulse sent by the electromagnetic excitation device. Specifically, the electromagnetic excitation device sequentially emits test electromagnetic pulses with a certain frequency to the test position of the duct. The vibration sensor detects the vibration of the steel strands at the test position due to the electromagnetic pulses and converts it into an electrical signal. Finally, the data acquisition device records the time curve of the vibration sensor data under the test electromagnetic pulse, that is, the test vibration timing data of the steel strands at the test position under the test electromagnetic pulse is obtained.

[0072] S520. Analyze the test vibration timing data to obtain the test peak data of the test vibration timing data and the test frequency data of the vibration of the steel strands under the test electromagnetic pulses.

[0073] Similarly, the test peak data may refer to the maximum amplitude data recorded through time series of the vibration signals generated by the resonance of the steel strand at the test position under an electromagnetic pulse with a specified frequency. Exemplarily, the maximum amplitude value of the vibration signal can be used as the test peak data, or the test vibration peak curve plotted when the maximum amplitude value changes with time can be used as the test peak data of the vibration signal. Similarly, it can be understood that the test frequency data may refer to the frequency data obtained by analyzing the vibration signals generated by the resonance of the steel strand at the test position under the test electromagnetic pulse.

[0074] Specifically, when the electromagnetic excitation device applies a test electromagnetic pulse to the test position, causing the steel strand to vibrate, the data acquisition device can record the vibration time series data at the corresponding frequency captured by the vibration sensor. By analyzing the time curve of these vibration time series data, the test peak data at the test position can be extracted. Further, by analyzing and processing the test peak data, the test frequency data of the vibration of the steel strand at the test position under the test electromagnetic pulse can be obtained. Exemplarily, the peak points of the vibration data measured at the test position can be plotted in chronological order to form a test peak curve, where the abscissa can represent time and the ordinate can represent the peak value, thus obtaining the test peak data of the vibration time series data at the test position. Further, the fast Fourier transform (FFT) or short-time Fourier transform (STFT) is applied to the vibration time series data to analyze the frequency components of the vibration signal, and the amplitude of the frequency components changing with frequency is plotted to form a test frequency curve, which is used as the test frequency data of the vibration of the steel strand at the test position under the test electromagnetic pulse. Among them, the abscissa can represent frequency and the ordinate can represent amplitude.

[0075] S530. Construct the frequency-length relationship data corresponding to the test electromagnetic pulse according to the test peak data and the test frequency data.

[0076] Similarly, the frequency-length relationship data is used to describe the corresponding relationship between the test frequency and the grouting defect length at the test position. Exemplarily, the frequency-length relationship data can be a table or database formed by mapping the test frequency data to the grouting defect length, or a polynomial function with the test frequency data as the independent variable and the grouting defect length as the dependent variable. Specifically, under the test electromagnetic pulse, for the duct models in different grouting defect states, calibration vibration detection is carried out at the test position to obtain the corresponding relationship between the test frequency data measured at the test position and the grouting defect length of the duct models in different grouting defect states.

[0077] In the above implementation, a calibration method for an electromagnetic wave detection device for grouting defects in prestressed ducts of bridges is provided, which can effectively provide a comparison standard for grouting defect detection of ducts in prestressed concrete structures. In particular, when it is necessary to determine the frequency-length relationship data at a specified frequency, the corresponding frequency-length relationship data can be directly searched in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency, thereby saving time and resources and further improving the efficiency of grouting defect detection of ducts in prestressed concrete structures.

[0078] The embodiment of this specification also provides an electromagnetic wave detection method for grouting defects in prestressed ducts of bridges, Figure 6a This is a schematic diagram of the scenario of this method, such as Figure 6a As shown, a hole 602 is provided in a concrete structure 604. After grouting the hole, the steel strand in the hole includes an area 606 filled with grouting material and an empty area 608 not filled with grouting material. An electromagnetic excitation device 610 and a vibration sensor 612 are deployed on the surface of the concrete structure. The electromagnetic excitation device 610 is used to transmit an electromagnetic pulse of a specified frequency to the detection position of the hole, and the vibration sensor 612 is used to detect the vibration signal caused by the electromagnetic pulse of the specified frequency to the steel strand at the detection position. The controller 614 is connected to a data acquisition device, and the controller 614 is connected to the electromagnetic excitation device 610 and the vibration sensor 612 respectively. Figure 6b is a flow chart of an electromagnetic wave detection method for grouting defects in prestressed ducts of bridges provided by the implementation mode of this specification in the above scenario, such as Figure 6b As shown, the method comprises the following steps:

[0079] S602. Determine vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor.

[0080] S604, analyzing the vibration time series data to obtain detection peak data of the vibration time series data and detection frequency data of the steel strand vibrating under an electromagnetic pulse of a specified frequency.

[0081] The electromagnetic pulse of the specified frequency includes a plurality of electromagnetic pulses with different pulse frequencies, and the electromagnetic excitation device is used to transmit electromagnetic pulses with different pulse frequencies to the detection position in a step-by-step manner in an increasing manner from small to large.

[0082] S606: When the detection peak data is less than the first calibration peak data, determine that the detection position is in a fully grouting state.

[0083] The first calibration peak data is determined in advance by using an electromagnetic pulse of a specified frequency to perform vibration detection on a pore model in a fully grouted state.

[0084] S608: Determine a target frequency interval in a frequency range corresponding to the detected frequency data.

[0085] S610. Calculate the mean value according to the target frequency range to obtain the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency.

[0086] S612. Search in the frequency-length relationship data according to the target vibration frequency to obtain the length of the grouting defect at the detection position.

[0087] Among them, the frequency-length relationship data is the corresponding relationship between the test frequency and the length of the grouting defect determined in advance by using the electromagnetic pulse of the specified frequency to perform vibration detection on the duct model in the state of grouting defect.

[0088] S614. In the case that there is an exceeding peak data greater than the second calibrated peak data in the detection peak data, determine the frequency range corresponding to the exceeding peak data.

[0089] Among them, the second calibrated peak data is determined in advance by using the electromagnetic pulse of the specified frequency to perform vibration detection on the duct model in the state of grouting defect.

[0090] S616. Calculate the mean value according to the frequency range corresponding to the exceeding peak data to obtain the target vibration frequency of the steel strand vibrating under the electromagnetic pulse of the specified frequency.

[0091] S618. Search in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency to obtain the relationship data corresponding to the pulse frequency as the frequency-length relationship data.

[0092] Among them, the relationship data set includes the frequency-length relationship data determined in advance by using multiple test electromagnetic pulses to perform vibration detection on the duct model in the state of grouting defect respectively.

[0093] S620. Search in the frequency-length relationship data according to the target vibration frequency to obtain the length of the grouting defect at the detection position.

[0094] It should be understood that although the steps in the above flow chart are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the above flow chart may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same moment, but can be executed at different moments. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or steps or stages in other steps.

[0095] The embodiment of this specification also provides an electromagnetic wave detection device 700 for the grouting defect of the prestressed duct of a bridge. The duct is arranged in a concrete structure, and there is grouting material and steel strands in the duct. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure. The electromagnetic excitation device is used to emit electromagnetic pulses with a specified frequency to the detection position of the duct. The specified frequency electromagnetic pulses include electromagnetic pulses with different pulse frequencies. The electromagnetic excitation device is used to adopt a step-by-step method to emit electromagnetic pulses with different pulse frequencies to the detection position in a gradually increasing manner from small to large. The vibration sensor is used to detect the vibration signal caused by the specified frequency electromagnetic pulses to the steel strands at the detection position. As Figure 7 shown, the device may include: a vibration data determination module 710, a peak frequency analysis module 720, and a grouting defect condition detection module 730, where:

[0096] The vibration data determination module 710 is used to determine the vibration time series data of the steel strands based on the vibration signals detected by the vibration sensor.

[0097] The peak frequency analysis module 720 is used to analyze the vibration time series data to obtain the detection peak data of the vibration time series data and the detection frequency data of the vibration of the steel strands under the specified frequency electromagnetic pulses.

[0098] The grouting defect condition detection module 730 is used to perform grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain the grouting defect detection result of the detection position.

[0099] In some embodiments, the grouting defect condition detection module 730 is further used to determine that the detection position is in a fully grouted state when the detection peak data is less than the first calibrated peak data, where the first calibrated peak data is determined by pre-using the specified frequency electromagnetic pulses to perform vibration detection on the duct model in a fully grouted state.

[0100] In some embodiments, the grouting defect condition detection module 730 is further used to determine a target frequency range within the frequency range corresponding to the detection frequency data. Calculate the mean value according to the target frequency range to obtain the target vibration frequency of the vibration of the steel strands under the specified frequency electromagnetic pulses. Search in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length of the detection position. The frequency-length relationship data is the corresponding relationship between the test frequency and the grouting defect length determined by pre-using the specified frequency electromagnetic pulses to perform vibration detection on the duct model in a grouting defect state.

[0101] In some embodiments, the grouting defect condition detection module 730 is further configured to determine a frequency range corresponding to the exceeded peak data in the detected peak data when there is exceeded peak data greater than the second calibrated peak data, where the second calibrated peak data is determined by previously performing vibration detection on a duct model in a grouting defect state using an electromagnetic pulse with a specified frequency. The length of the grouting defect at the detection position is determined according to the relationship between the frequency range corresponding to the exceeded peak data and the frequency-length relationship data, where the frequency-length relationship data is the corresponding relationship between the test frequency and the length of the grouting defect determined by previously performing vibration detection on a duct model in a grouting defect state using an electromagnetic pulse with a specified frequency.

[0102] In some embodiments, the grouting defect condition detection module 730 is further configured to determine the length of the grouting defect at the detection position according to the relationship between the frequency range corresponding to the exceeded peak data and the frequency-length relationship data, including: calculating an average value according to the frequency range corresponding to the exceeded peak data to obtain the target vibration frequency of the steel strand vibrating under the electromagnetic pulse with the specified frequency. Searching in the frequency-length relationship data according to the target vibration frequency to obtain the length of the grouting defect at the detection position.

[0103] In some embodiments, the electromagnetic wave detection device 700 for grouting defects in bridge prestressed ducts further includes a frequency-length relationship determination module, configured to search in the relationship data set according to the pulse frequency of the electromagnetic pulse with the specified frequency to obtain the relationship data corresponding to the pulse frequency as the frequency-length relationship data, where the relationship data set includes the frequency-length relationship data determined by previously performing vibration detection on a duct model in a grouting defect state using multiple test electromagnetic pulses respectively.

[0104] For the specific limitations of an electromagnetic wave detection device for grouting defects in bridge prestressed ducts, reference may be made to the limitations of an electromagnetic wave detection method for grouting defects in bridge prestressed ducts described above, which will not be elaborated here. Each module in the above electromagnetic wave detection device for grouting defects in bridge prestressed ducts can be implemented in whole or in part by software, hardware, and their combination.

[0105] The embodiments of this specification also provide an electromagnetic wave detection calibration device 800 for grouting defects in bridge prestressed ducts. The electromagnetic wave detection device for grouting defects in bridge prestressed ducts includes an electromagnetic excitation device and a vibration sensor. The electromagnetic excitation device and the vibration sensor are deployed on the surface of the concrete model. There is a duct model in the concrete model, and there is grouting material and steel strands in the duct model. The electromagnetic excitation device is configured to emit a test electromagnetic pulse to a test position of the duct model, and the vibration sensor is configured to detect the vibration signal caused by the test electromagnetic pulse to the steel strand at the test position. As Figure 8 shown, it includes: a test vibration data determination module 810, a test frequency determination module 820, and a frequency-length relationship determination module 830, where:

[0106] A test vibration data determination module 810 is configured to determine test vibration timing data of the steel strand based on vibration signals detected by a vibration sensor.

[0107] A test frequency determination module 820 is configured to analyze the test vibration timing data to obtain test peak data of the test vibration timing data and test frequency data of the vibration of the steel strand under a test electromagnetic pulse.

[0108] A frequency-length relationship determination module 830 is configured to construct frequency-length relationship data corresponding to the test electromagnetic pulse according to the test peak data and the test frequency data. The frequency-length relationship data is used to describe the corresponding relationship between the test frequency and the length of the grouting defect at the test position.

[0109] For the specific limitations of a device for calibrating electromagnetic wave detection of grouting defects in prestressed ducts of bridges, reference can be made to the limitations of the method for calibrating electromagnetic waves in the method for detecting grouting defects in prestressed ducts of bridges described above, which will not be elaborated here. Each module in the above device for calibrating electromagnetic wave detection of grouting defects in prestressed ducts of bridges can be implemented in whole or in part by software, hardware, and their combinations. The above modules can be embedded in the processor of the computer device in hardware form or be independent of it, or be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0110] The embodiment of the present specification also provides a device 900 for detecting electromagnetic waves of grouting defects in prestressed ducts of bridges, as Figure 9 shown, including: an electromagnetic excitation device 910, a vibration sensor 920, a data acquisition device 930, and a controller 940. The electromagnetic excitation device 910 and the vibration sensor 920 are respectively used to be deployed on the surface of the concrete structure, and there is grouting material and steel strands in the ducts in the concrete structure. The controller 940 is respectively connected to the electromagnetic excitation device 910 and the vibration sensor 920, and the vibration sensor 920 is connected to the data acquisition device 930.

[0111] The electromagnetic excitation device 910 is configured to emit a test electromagnetic pulse to the detection position of the duct.

[0112] The vibration sensor 920 is configured to detect vibration signals caused by the test electromagnetic pulse to the steel strand at the detection position.

[0113] The data acquisition device 930 is configured to determine vibration timing data of the steel strand based on the vibration signals detected by the vibration sensor.

[0114] The controller 940 is configured to perform grouting defect detection on the detection position according to the vibration timing data to obtain a grouting defect detection result of the detection position.

[0115] An electromagnetic wave detection device for bridge prestressed duct grouting defects in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0116] An embodiment of the present application also provides a computer device, which can be a terminal, and its internal structure diagram can be as Figure 10 shown. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it realizes an electromagnetic wave detection method for bridge prestressed duct grouting defects. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, a trackball, or a touchpad set on the shell of the computer device, or an external keyboard, a touchpad, or a mouse, etc.

[0117] An embodiment of the present application also provides a computer-readable storage medium. The method according to the embodiment of the present application can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be processed by such software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiment is realized.

[0118] An embodiment of the present application provides a computer program product, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, causing the computer device to execute the method of any embodiment of the present application. The electromagnetic wave detection method and device for the grouting defect of the bridge prestressed duct described in the above embodiment can be specifically implemented by a computer chip or an entity, or implemented by a product with a certain function. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices. For the convenience of description, when describing the above device, it is divided into various units according to functions and described separately. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0119] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of methods, devices, and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for implementing in the process Figure 1 one process or multiple processes and / or blocks Figure 1 a device for the functions specified in one block or multiple blocks.

[0120] In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined. It should also be noted that the terms "comprising" and "including" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity, or device comprising a series of elements not only includes those elements but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, commodity, or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, commodity, or device comprising the element.

[0121] The various embodiments in this specification are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments. In particular, for computer devices, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments.

[0122] The above are only the embodiments of this application and are not used to limit this application. For those skilled in the art, various changes and modifications can be made to this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

[0123] Although the embodiments of this application are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An electromagnetic wave detection method for grouting defects in prestressed ducts of bridges, characterized in that: The duct is arranged in a concrete structure, and has grouting material and steel strands in the duct, and the steel strands have a good response to electromagnetic pulses. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure; the electromagnetic pulse frequency that is most likely to cause resonance of the steel strands is taken as the designated frequency of the electromagnetic excitation device to send the electromagnetic pulse, and the pulse frequency of the electromagnetic pulse with the designated frequency is multiple; the electromagnetic excitation device is used to transmit an electromagnetic pulse with the designated frequency to a detection position of the duct, and the vibration sensor is used to detect the vibration signal caused by the electromagnetic pulse with the designated frequency on the steel strands at the detection position; the method comprises: Determining vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor; Analyzing the vibration time series data to obtain detection peak data of the vibration time series data and detection frequency data of the steel strand vibrating under the electromagnetic pulse of the specified frequency; Performing grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain a grouting defect detection result of the detection position to detect whether there is a gap or grouting defect between the bonding between the grouting material and the steel strand in the duct; Specifically including: searching in the relational data set according to the pulse frequency of the electromagnetic pulse of the specified frequency to obtain the relational data corresponding to the pulse frequency as the frequency-length relational data; wherein, obtaining the grouting defect detection result of the detection position according to the detection peak data, including: in the case where there is excess peak data greater than the second calibration peak data in the detection peak data, determining the frequency interval corresponding to the excess peak data; performing mean calculation according to the frequency interval corresponding to the excess peak data to obtain the target vibration frequency of the steel strand under the electromagnetic pulse of the specified frequency; searching in the frequency-length relational data according to the target vibration frequency to obtain the grouting defect length at the detection position; wherein, the frequency-length relational data is the correspondence between the test frequency and the grouting defect length determined in advance by performing vibration detection on the pore model under the grouting defect state using the electromagnetic pulse of the specified frequency; the relational data set includes performing vibration detection on the pore model under different grouting defect states under multiple test electromagnetic pulses, and obtaining the correspondence between the test frequency data and the grouting defect length measured at the test position of the pore model under different grouting defect states under multiple test electromagnetic pulses; The grouting defect detection result of the detection position is obtained according to the detection frequency data, including: determining a target frequency interval in the frequency range corresponding to the detection frequency data; performing mean calculation according to the target frequency interval to obtain a target vibration frequency of the steel strand vibrating under an electromagnetic pulse of a specified frequency; and performing a search in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length of the detection position.

2. The method according to claim 1, characterized in that The step of performing grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain a grouting defect detection result at the detection position further includes: When the detection peak value data is smaller than the first calibration peak value data, it is determined that the detection position is in a fully grouting state.

3. The method according to claim 2, characterized in that The first calibration peak data is determined in advance by performing vibration detection on the pore model in a fully grouting state using the electromagnetic pulse of the specified frequency.

4. The method according to claim 1, characterized in that: The second calibration peak data is determined in advance by performing vibration detection on the pore model in the grouting defect state using the electromagnetic pulse of the specified frequency.

5. The method according to claim 1, characterized in that The electromagnetic pulse of designated frequency includes a plurality of electromagnetic pulses with different pulse frequencies.

6. The method according to claim 5, characterized in that The electromagnetic excitation device adopts a step-by-step method to emit electromagnetic pulses with different pulse frequencies to the detection position in a step-by-step manner.

7. An electromagnetic wave detection device for grouting defects in prestressed ducts of bridges, characterized in that: The duct is arranged in a concrete structure, and has grouting material and steel strands in the duct, and the steel strands have a good response to electromagnetic pulses. An electromagnetic excitation device and a vibration sensor are deployed on the surface of the concrete structure; the electromagnetic pulse frequency that is most likely to cause resonance of the steel strands is taken as the designated frequency of the electromagnetic excitation device to send the electromagnetic pulse, and the pulse frequency of the electromagnetic pulse with the designated frequency is multiple; the electromagnetic excitation device is used to transmit an electromagnetic pulse with the designated frequency to the detection position of the duct, and the vibration sensor is used to detect the vibration signal caused by the electromagnetic pulse with the designated frequency on the steel strands at the detection position; the device comprises: A vibration data determination module, used to determine the vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor; A peak frequency analysis module, used for analyzing the vibration time series data to obtain detection peak data of the vibration time series data and detection frequency data of the steel strand vibrating under the electromagnetic pulse of the specified frequency; A grouting defect detection module is used to perform grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data, and obtain the grouting defect detection result of the detection position, so as to detect whether there are gaps or grouting defects in the bonding between the grouting material and the steel strand in the channel; specifically comprising: searching in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency, and obtaining the relationship data corresponding to the pulse frequency as frequency-length relationship data; wherein, obtaining the grouting defect detection result of the detection position according to the detection peak data comprises: in the case where there is excess peak data greater than the second calibration peak data in the detection peak data, determining the frequency interval corresponding to the excess peak data; performing mean calculation according to the frequency interval corresponding to the excess peak data, and obtaining the target vibration frequency of the steel strand under the electromagnetic pulse of the specified frequency; searching in the frequency-length relationship data according to the target vibration frequency, The grouting defect length at the detection position is obtained; wherein the frequency-length relationship data is the correspondence between the test frequency and the grouting defect length determined in advance by using the specified frequency electromagnetic pulse to perform vibration detection on the channel model under the grouting defect state; the relationship data set includes the correspondence between the test frequency data and the grouting defect length measured at the test position of the channel model with different grouting defect states under multiple test electromagnetic pulses for vibration detection; the grouting defect detection result at the detection position is obtained according to the detection frequency data, including: determining a target frequency interval in the frequency range corresponding to the detection frequency data; performing mean calculation according to the target frequency interval to obtain the target vibration frequency of the steel strand vibrating under the specified frequency electromagnetic pulse; searching in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length at the detection position.

8. An electromagnetic wave detection device for grouting defects in prestressed ducts of bridges, characterized in that: The electromagnetic wave detection device for grouting defects in prestressed ducts of bridges comprises a controller, a data acquisition device, an electromagnetic excitation device and a vibration sensor; the electromagnetic excitation device and the vibration sensor are respectively deployed on the surface of a concrete structure, and the duct in the concrete structure has grouting material and steel strands; the steel strands have a good response to electromagnetic pulses, the controller is respectively connected to the electromagnetic excitation device and the vibration sensor, and the vibration sensor is connected to the data acquisition device; The electromagnetic excitation device is used to transmit electromagnetic pulses of a specified frequency to the detection position of the hole; the electromagnetic pulse frequency that is most likely to cause the steel strand to resonate is taken as the specified frequency of the electromagnetic pulse sent by the electromagnetic excitation device, and the pulse frequency of the electromagnetic pulse of the specified frequency is multiple; The vibration sensor is used to detect the vibration signal caused by the electromagnetic pulse of the specified frequency on the steel strand at the detection position; The data acquisition device is used to determine the vibration time series data of the steel strand based on the vibration signal detected by the vibration sensor; The controller is used to analyze the vibration time series data to obtain the detection peak data of the vibration time series data and the detection frequency data of the steel strand vibrating under the specified frequency electromagnetic pulse; perform grouting defect detection on the detection position according to the detection peak data and / or the detection frequency data to obtain the grouting defect detection result of the detection position, so as to detect whether there is a gap or grouting defect in the bonding between the grouting material and the steel strand in the channel; specifically including: searching in the relationship data set according to the pulse frequency of the electromagnetic pulse of the specified frequency to obtain the relationship data corresponding to the pulse frequency as frequency-length relationship data; wherein, obtaining the grouting defect detection result of the detection position according to the detection peak data includes: in the case where there is excess peak data greater than the second calibration peak data in the detection peak data, determining The frequency interval corresponding to the exceeded peak data; perform mean calculation based on the frequency interval corresponding to the exceeded peak data to obtain the target vibration frequency of the steel strand under the specified frequency electromagnetic pulse; perform search in the frequency-length relationship data based on the target vibration frequency to obtain the grouting defect length at the detection position; wherein the frequency-length relationship data is the correspondence between the test frequency and the grouting defect length determined in advance by performing vibration detection on the pore model under the grouting defect state using the specified frequency electromagnetic pulse; the relationship data set includes the correspondence between the test frequency data and the grouting defect length measured at the test position of the pore model under different grouting defect states under multiple test electromagnetic pulses by performing vibration detection on the pore model under different grouting defect states; The grouting defect detection result of the detection position is obtained according to the detection frequency data, including: determining a target frequency interval in the frequency range corresponding to the detection frequency data; performing mean calculation according to the target frequency interval to obtain a target vibration frequency of the steel strand vibrating under an electromagnetic pulse of a specified frequency; and performing a search in the frequency-length relationship data according to the target vibration frequency to obtain the grouting defect length of the detection position.

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