Post-tensioned prestressed concrete structure duct grouting void length quantification method based on ultrasonic guided waves
By collecting and analyzing ultrasonic guide signals in the post-tension prestressed concrete structure, calculating the nonlinear parameters of longitudinal guide waves, and determining the grouting drainage length, the problem that traditional detection methods are difficult to accurately quantify the grouting drainage length is solved, and a high-precision and low-cost detection effect is achieved.
Patent Information
- Application Number
- CN202510325001.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-13
AI Technical Summary
Traditional testing methods are difficult to accurately quantify the length of grouting and de-empty discharge in post-tension prestressed concrete structures, and are insufficiently sensitive to tiny discharge. Due to the inhomogeneity of concrete materials and multiple reflections on the interface, it is difficult to achieve accurate quantification.
Using an ultrasonic waveguide method, ultrasonic waveguide signals are collected at the cross sections of both ends of steel strands in the post-tension prestressed concrete structure, the signal is converted into the frequency domain using fast Fourier transform, the amplitude of the second frequency and the third frequency are determined, the nonlinear parameters of the longitudinal guide wave are calculated, and the grouting and drainage length is determined through a predetermined functional relationship.
The precise quantification of the grouting and de-empty length in the post-tension prestressed concrete structure is achieved, which overcomes the shortcomings of traditional methods, improves the detection accuracy and reliability, and does not need to rely on baseline data, which has high sensitivity, high accuracy, simple operation, and low cost.
Smart Images
Figure CN120142459A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of grouting void detection, and particularly relates to a method for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves. Background Art
[0002] In post-tensioned prestressed concrete structures, grouting compactness is a key factor to ensure the coordinated work of steel strands and surrounding concrete, prevent corrosion and structural failure. However, construction process defects or long-term environmental erosion easily lead to voids at the interface between the grouting layer and the steel strands. The early detection and quantitative evaluation of such defects are crucial for structural safety. Traditional detection methods such as the tapping method and guided wave techniques based on linear ultrasonic parameters have significant limitations: the tapping method relies on the operator's experience and cannot perform quantitative analysis; linear ultrasonic guided wave techniques (such as amplitude attenuation and wave velocity change) are not sensitive enough to small voids, and are affected by the non-uniformity of concrete materials, multiple reflections at the steel strand - grouting interface and boundary effects, making it difficult to accurately quantify the void length. Therefore, there is an urgent need for a method to accurately evaluate grouting defects in post-tensioned prestressed concrete structures. Summary of the Invention
[0003] In view of this, the purpose of the present invention is to provide a method and device for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves to meet the need for accurately evaluating grouting defects in post-tensioned prestressed concrete structures.
[0004] To achieve the above purpose, the present invention provides the following technical solutions:
[0005] According to the first aspect, the present invention provides a method for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves, including: using a signal with a center frequency of the first frequency as the excitation signal, and collecting the ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure under the excitation signal; performing a fast Fourier transform to convert the ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure from the time domain to the frequency domain to obtain the first ultrasonic guided wave frequency domain signal; determining the amplitude at the second frequency and the amplitude at the third frequency in the first ultrasonic guided wave frequency domain signal, where the third frequency is the second harmonic of the second frequency; determining the first longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency; inputting the first longitudinal guided wave nonlinear parameter into a function of the longitudinal guided wave nonlinear parameter varying with the void length determined in advance to determine the void length of the duct grouting in the target post-tensioned prestressed concrete structure.
[0006] Optionally, the process of determining the function of the longitudinal guided wave nonlinear parameter varying with the void length includes:
[0007] S1. Use the signal with the first frequency as the center frequency as the excitation signal, and collect the ultrasonic guided wave signals at both ends of the strand in the void simulation structure under the excitation signal. The void simulation structure is a grouting void structure with the target material wrapped around the surface of the strand with the target length, and the simulated void length is the target length.
[0008] S2. Use the fast Fourier transform to convert the ultrasonic guided wave signals at both ends of the strand in the void simulation structure from the time domain to the frequency domain to obtain the second ultrasonic guided wave frequency domain signal.
[0009] S3. In the second ultrasonic guided wave frequency domain signal, determine the amplitude at the second frequency and the amplitude at the third frequency.
[0010] S4. Determine the second longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency.
[0011] S5. Judge whether the number of the second longitudinal guided wave nonlinear parameters meets the preset requirements. If not, execute S6; if so, execute S7.
[0012] S6. Increase the void length of the void simulation structure and repeat steps S1 - S5.
[0013] S7. Fit multiple second longitudinal guided wave nonlinear parameters to obtain the function of the longitudinal guided wave nonlinear parameter varying with the void length.
[0014] Optionally, determining the first longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency includes:
[0015]
[0016] where β 1 is the first longitudinal guided wave nonlinear parameter, A 1 (f) is the amplitude of the first ultrasonic guided wave frequency domain at the second frequency, and A 1 (2f) is the amplitude of the first ultrasonic guided wave frequency domain at the third frequency.
[0017] Optionally, the function of the longitudinal guided wave nonlinear parameter varying with the void length is:
[0018] β = β 0 + kl;
[0019] where β 0 represents the nonlinear parameter in the non - void state, l represents the void length value, and k is the slope of the fitting equation, representing the proportional coefficient of the nonlinear parameter varying with the void length.
[0020] Optionally, the target material is any one of EPE, low - density foam, and airbag.
[0021] Optionally, an ultrasonic guided wave sensor is used to collect ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure under an excitation signal in a one-transmitter-and-one-receiver manner. The ultrasonic guided wave sensor includes an excitation sensor and a receiving sensor. The excitation sensor is used to convert an electrical signal into an ultrasonic guided wave signal and transmit it to the steel strand in the target post-tensioned prestressed concrete structure, and the receiving sensor is used to receive the ultrasonic guided wave signal propagated through the steel strand.
[0022] According to a second aspect, the present invention provides a device for quantifying the length of grouting voids in a post-tensioned prestressed concrete structure based on ultrasonic guided waves, including: a signal acquisition module for using a signal with a center frequency of a first frequency as an excitation signal to collect ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure under the excitation signal; a Fourier transform module for using fast Fourier transform to convert the ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure from the time domain to the frequency domain to obtain a first ultrasonic guided wave frequency domain signal; an amplitude determination module for determining the amplitude at a second frequency and the amplitude at a third frequency in the first ultrasonic guided wave frequency domain signal, where the third frequency is the second harmonic of the second frequency; a longitudinal guided wave nonlinear parameter determination module for determining a first longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency; and a void length determination module for inputting the first longitudinal guided wave nonlinear parameter into a pre-determined function of the longitudinal guided wave nonlinear parameter varying with the void length to determine the length of grouting voids in the target post-tensioned prestressed concrete structure.
[0023] According to a third aspect, an embodiment of the present invention provides an electronic device, the device including: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the steps of the method for quantifying the length of grouting voids in a post-tensioned prestressed concrete structure based on ultrasonic guided waves according to the first aspect or any implementation manner of the first aspect.
[0024] According to a fourth aspect, an embodiment of the present invention provides a computer storage medium, on which a computer instruction is stored, and when the instruction is executed by a processor, it implements the steps of the method for quantifying the length of grouting voids in a post-tensioned prestressed concrete structure based on ultrasonic guided waves according to the first aspect or any implementation manner of the first aspect.
[0025] An embodiment of the present invention provides a method for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves. When ultrasonic waves propagate in a non-uniform medium (such as a grouting structure with voids), material micro-defects will cause waveform distortion and generate higher-order harmonic components (such as second harmonics). Moreover, the void at the steel strand-grout interface will change the guided wave propagation boundary conditions, resulting in a redistribution of the longitudinal guided wave mode energy. Therefore, the present invention defines a non-linear parameter by using the fundamental frequency and the amplitude of the second harmonic, establishes a functional relationship with the void length, and thus realizes quantification. It can overcome the deficiencies of traditional methods, improve the detection accuracy and reliability, and does not require relying on baseline data. It has the advantages of high sensitivity, high accuracy, simple operation, and low cost, providing a new idea for quantifying the void length of grouting.
[0026] Other advantages, objectives, and features of the present invention will be described in the subsequent specification, and to some extent, they are obvious to those skilled in the art, or those skilled in the art can obtain teachings from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the following drawings are provided for description:
[0028] Figure 1 It is a flowchart of a specific example of a method for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves in the present invention;
[0029] Figure 2 It is a flowchart of a specific example of the process for determining the function of the longitudinal guided wave non-linear parameter varying with the void length in the present invention;
[0030] Figure 3 It is a schematic block diagram of a specific example of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0031] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention fall within the protection scope of the present invention.
[0032] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may also be the communication inside two components. It may be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0033] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0034] An embodiment of the present invention provides a method for quantifying the length of voids in grouting of ducts in a post-tensioned prestressed concrete structure based on ultrasonic guided waves, as Figure 1 shown, including:
[0035] S101, using a signal with a central frequency of a first frequency as an excitation signal, and collecting ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure under the excitation signal;
[0036] S102, using fast Fourier transform to convert the ultrasonic guided wave signals at both ends of the steel strand in the target post-tensioned prestressed concrete structure from the time domain to the frequency domain to obtain a first ultrasonic guided wave frequency domain signal;
[0037] S103, in the first ultrasonic guided wave frequency domain signal, determining the amplitude at a second frequency and the amplitude at a third frequency, where the third frequency is the second harmonic of the second frequency;
[0038] S104, determining a first longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency;
[0039] S105, inputting the first longitudinal guided wave nonlinear parameter into a function of the longitudinal guided wave nonlinear parameter varying with the void length determined in advance to determine the void length in grouting in the target post-tensioned prestressed concrete structure.
[0040] Exemplarily, a post-tensioned prestressed concrete structure is a prestressed concrete structure constructed by the post-tensioning method. Its main feature is that the concrete member is first cast, and a duct is reserved in the member. After the concrete reaches a certain strength, generally more than 75% of the design strength, then the prestressing tendon is inserted and tensioned, and the tensioned prestressing tendon is anchored at the end of the member through an anchor to generate precompressive stress in the concrete. The target post-tensioned prestressed concrete structure is a post-tensioned prestressed concrete structure for which the void length in grouting is to be determined.
[0041] In this embodiment, the ultrasonic guided wave signals of the cross-sections at both ends of the steel strands in the target post-tensioned prestressed concrete structure are collected in a one-transmitter-one-receiver manner. Specifically, ultrasonic guided wave sensors are installed at the cross-sections at both ends of the steel strands to ensure good contact between the sensors and the steel strands. It should be noted that the ultrasonic guided wave sensors are installed at the entire end of the steel strand, rather than on a single wire. The ultrasonic sensor includes an excitation sensor and a receiving sensor. A sine signal with a center frequency of the first frequency modulated by a Hanning window is applied to the excitation sensor, and then the electrical signal is converted into an ultrasonic guided wave signal and transmitted to the steel strands in the target post-tensioned prestressed concrete structure. At the same time, the ultrasonic guided wave signals received on the receiving sensor after propagating through the steel strands are recorded, where the first frequency can be expressed as f.
[0042] The collected ultrasonic guided wave time-domain signals are converted into frequency-domain signals through FFT, and the obtained first ultrasonic guided wave frequency-domain signals can be further analyzed for their frequency components and amplitude distributions. The positions of the second frequency and the third frequency are determined in the first ultrasonic guided wave frequency-domain signals, where the second frequency can also be f. As the fundamental frequency, the amplitude at the double frequency 2f is generated by the contact acoustic nonlinearity caused by the debonding. Therefore, the third frequency can be twice the second frequency. According to the positions of the second frequency and the third frequency, the amplitude A 1 (f) of the first ultrasonic guided wave frequency-domain at the second frequency and the amplitude A 1 (2f) of the first ultrasonic guided wave frequency-domain at the third frequency are extracted respectively. The amplitude can be determined by the peak value or the energy spectrum of the frequency-domain signal.
[0043] According to the amplitude A 1 (f) of the first ultrasonic guided wave frequency-domain at the second frequency and the amplitude A 1 (2f) of the first ultrasonic guided wave frequency-domain at the third frequency, the first longitudinal guided wave nonlinear parameter β 1 is determined, including:
[0044]
[0045] After obtaining the first longitudinal guided wave nonlinear parameter β 1 , the longitudinal guided wave nonlinear parameter β 1 is input into a function that pre-determines the variation of the longitudinal guided wave nonlinear parameter with the debonding length. The function is as follows:
[0046] β = β 0 + kl;
[0047] where β is the longitudinal guided wave nonlinear parameter, β 0 represents the nonlinear parameter in the non-debonding state, l represents the debonding length value, and k is the slope of the fitting equation, representing the proportional coefficient of the variation of the nonlinear parameter with the debonding length. In this function, β 0where k is a known parameter, and through the transformation of the above formula, we can obtain:
[0048]
[0049] Under the derivation of the above formula, substituting the first longitudinal guided wave nonlinear parameter β 1 into β, the grouting void length l in the post-tensioned prestressed concrete structure can be obtained:
[0050]
[0051] The embodiment of the present invention provides a method for quantifying the grouting void length in a post-tensioned prestressed concrete structure based on ultrasonic guided waves. By considering that when ultrasonic waves propagate in a non-uniform medium (such as a grouting structure with voids), material micro-defects will cause waveform distortion and generate high-order harmonic components (such as second harmonics), and the void at the steel strand - grouting interface will change the guided wave propagation boundary conditions, resulting in the redistribution of the longitudinal guided wave mode energy. Therefore, the present invention defines the nonlinear parameter by adopting the fundamental frequency and the amplitude of the second harmonic, establishes a functional relationship with the void length, thereby realizing quantification, which can overcome the deficiencies of traditional methods, improve the detection accuracy and reliability, and does not require relying on baseline data, with advantages such as high sensitivity, high accuracy, simple operation, and low cost, providing a new idea for the quantification of the grouting void length.
[0052] As an optional implementation manner, the process of determining the function of the longitudinal guided wave nonlinear parameter varying with the void length is as Figure 2 shown, and includes:
[0053] S1. Using a signal with the center frequency as the first frequency as the excitation signal, collecting the ultrasonic guided wave signals at both ends of the steel strand in the void simulation structure under the excitation signal. The void simulation structure is a grouting void structure with the simulated void length being the target length, which is obtained by surrounding the steel strand with the target length with the target material;
[0054] S2. Using the fast Fourier transform to convert the ultrasonic guided wave signals at both ends of the steel strand in the void simulation structure from the time domain to the frequency domain, obtaining the second ultrasonic guided wave frequency domain signal;
[0055] S3. In the second ultrasonic guided wave frequency domain signal, determining the amplitude at the second frequency and the amplitude at the third frequency;
[0056] S4. According to the amplitude at the second frequency and the amplitude at the third frequency, determining the second longitudinal guided wave nonlinear parameter;
[0057] S5. Judging whether the number of the second longitudinal guided wave nonlinear parameters meets the preset requirements. If not, execute S6; if so, execute S7;
[0058] S6. Increase the debonding length of the debonding simulation structure, and repeat steps S1 - S5;
[0059] S7. Fit multiple second longitudinal guided wave nonlinear parameters to obtain a function of the longitudinal guided wave nonlinear parameter varying with the debonding length.
[0060] Exemplarily, grouting debonding refers to the situation in a prestressed structure where there are voids between the steel strands and the concrete due to non - dense grouting, which affects the transfer of prestress and the uplift resistance of the structure. Therefore, materials with the same properties can be used to simulate the grouting debonding structure, such as EPE. EPE has certain elasticity, softness, and heat - insulation properties, which can isolate the contact with the grouting material. The wrapping layer formed on the surface of the steel strand by EPE can simulate this debonding state. In addition, low - density foam and airbags can also be used. The method of using EPE to simulate the grouting debonding structure with the target length as the debonding length can be to wind the EPE around the steel strand surface for the target length. It should be noted that the target length can start from 0 and gradually increase, and the increasing method can be equidistant increase. In this embodiment, an example with a target length of 0.5 meters is used for illustration. In the embodiment of the present invention, the ultrasonic guided wave signals at both ends of the cross - section of the steel strand in the debonding simulation structure are also collected in a one - transmit - one - receive manner. The specific transmitting and receiving processes refer to the corresponding parts in the above - mentioned embodiment and will not be elaborated here. It should be noted that the ultrasonic guided wave excitation and receiving sensors are installed at the end of the entire steel strand as described above, rather than on a single wire, and the first frequency is f.
[0061] For the ultrasonic guided wave signals at both ends of the cross - section of the steel strand in the debonding simulation structure, fast Fourier transform is also used to convert the ultrasonic guided wave signals at both ends of the cross - section of the steel strand in the debonding simulation structure from the time domain to the frequency domain, obtaining the second ultrasonic guided wave frequency - domain signal. In the second ultrasonic guided wave frequency - domain signal, determine the amplitude at the second frequency and the amplitude at the third frequency. Among them, the second frequency and the third frequency can still be f and 2f. The amplitude A 2 (f) of the second ultrasonic guided wave frequency - domain signal at the second frequency f and the amplitude A 2 (2f) at the third frequency 2f.
[0062] According to the amplitude A 2 (f) at the second frequency and the amplitude A 2 (2f) at the third frequency, the specific formula for determining the second longitudinal guided wave nonlinear parameter is as follows:
[0063]
[0064] Among them, β 21 represents the second longitudinal guided wave nonlinear parameter in the grouting debonding structure with the debonding length as the target length.
[0065] To obtain sufficient second longitudinal guided wave nonlinear parameters, it is also necessary to vary the debonding length. For example, increase the debonding length of the debonding simulation structure. Thus, the target length can be changed from 0.5 meters to 1 meter, that is, wrap the pearl cotton around the surface of the steel strand for 1 meter. Repeat steps S1 - S5 until n second longitudinal guided wave nonlinear parameters {β 21 ,β 22 ...β 2n} are obtained. Here, n can be a preset quantity. That is, when n second longitudinal guided wave nonlinear parameters are obtained, stop the loop and enter step S6. Since the nonlinear parameter increases with the increase of the debonding length and the relationship between the two can be approximated as a linear relationship, therefore, fit the n second longitudinal guided wave nonlinear parameters to obtain a function of the longitudinal guided wave nonlinear parameter varying with the debonding length. This function is as described above and will not be elaborated here.
[0066] This embodiment gives the experimental data of the error between the grouting debonding length and the actual debonding length in the post - tensioned prestressed concrete structure determined by the above method:
[0067]
[0068] The results show that the relative error of the estimated debonding length by this method is within 10%, with high accuracy.
[0069] The present invention provides a device for quantifying the grouting debonding length in a post - tensioned prestressed concrete structure based on ultrasonic guided waves, including:
[0070] A signal acquisition module, which is used to use a signal with a central frequency of the first frequency as the excitation signal and acquire the ultrasonic guided wave signals at both ends of the steel strand in the target post - tensioned prestressed concrete structure under the excitation signal;
[0071] A Fourier transform module, which is used to convert the ultrasonic guided wave signals at both ends of the steel strand in the target post - tensioned prestressed concrete structure from the time domain to the frequency domain by using the fast Fourier transform to obtain the first ultrasonic guided wave frequency domain signal;
[0072] An amplitude determination module, which is used to determine the amplitude at the second frequency and the amplitude at the third frequency in the first ultrasonic guided wave frequency domain signal, where the third frequency is the second - harmonic of the second frequency;
[0073] A longitudinal guided wave nonlinear parameter determination module, which is used to determine the first longitudinal guided wave nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency;
[0074] A debonding length determination module, which is used to input the first longitudinal guided wave nonlinear parameter into the function of the longitudinal guided wave nonlinear parameter varying with the debonding length determined in advance to determine the grouting debonding length in the target post - tensioned prestressed concrete structure.
[0075] The embodiments of the present application further provide an electronic device, such as Figure 3 shown, a processor 501 and a memory 502, where the processor 501 and the memory 502 may be connected through a bus or other means.
[0076] The processor 501 may be a central processing unit (CPU). The processor 501 may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. chips, or a combination of the above types of chips.
[0077] The memory 502, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the method for quantifying the length of voids in grouting of ducts in a post-tensioned prestressed concrete structure based on ultrasonic guided waves in the embodiments of the present invention. The processor executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory.
[0078] The memory 502 may include a program storage area and a data storage area. Among them, the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created by the processor, etc. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory 502 may optionally include a memory remotely provided relative to the processor, and these remote memories may be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.
[0079] The one or more modules are stored in the memory 502 and, when executed by the processor 501, execute the method for quantifying the length of voids in grouting of ducts in a post-tensioned prestressed concrete structure based on ultrasonic guided waves in the embodiments as Figure 1 shown.
[0080] For specific details of the above electronic device, reference may be made to Figure 1For the corresponding related descriptions and effects in the illustrated embodiments, understanding can be achieved and will not be elaborated here.
[0081] This embodiment also provides a computer storage medium. The computer storage medium stores computer-executable instructions, and these computer-executable instructions can execute the method for quantifying the void length of duct grouting in a post-tensioned prestressed concrete structure based on ultrasonic guided waves in any of the above method embodiments. Among them, the storage medium can be a magnetic disk, an optical disc, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (abbreviation: HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.
[0082] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.
Claims
1. A method for quantifying the length of grouting voids in post-tensioned concrete structures based on ultrasonic guided waves, characterized in that: include: A signal with a center frequency of the first frequency is used as an excitation signal, and ultrasonic guided wave signals of cross sections at both ends of the steel strand in the target post-tensioned prestressed concrete structure are collected under the excitation signal; By using fast Fourier transform, the ultrasonic guided wave signals of the cross sections of the steel strands at both ends of the target post-tensioned prestressed concrete structure are converted from the time domain to the frequency domain to obtain a first ultrasonic guided wave frequency domain signal; In the first ultrasonic guided wave frequency domain signal, determining an amplitude at a second frequency and an amplitude at a third frequency, wherein the third frequency is a second harmonic of the second frequency; Determine a first longitudinal waveguide nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency; The first longitudinal guided wave nonlinear parameter is input into a predetermined function of the longitudinal guided wave nonlinear parameter varying with the void length, and the grouting void length in the target post-tensioned prestressed concrete structure is determined.
2. The method for quantifying the void length of grouting in post-tensioned concrete structure based on ultrasonic guided waves according to claim 1 is characterized in that: The process of determining the function of the longitudinal waveguide nonlinear parameters changing with the void length includes: S1, using a signal with a center frequency of the first frequency as an excitation signal, collecting ultrasonic guided wave signals of the cross sections of both ends of the steel strand in the hollow simulation structure under the excitation signal, the hollow simulation structure is a grouting hollow structure in which the target material is surrounded by the surface of the steel strand of the target length, and the hollow length obtained by simulation is the target length; S2, using fast Fourier transform, converting the ultrasonic guided wave signals of the cross sections of the steel strands at both ends of the hollow simulation structure from the time domain to the frequency domain, and obtaining a second ultrasonic guided wave frequency domain signal; S3, determining an amplitude at the second frequency and an amplitude at the third frequency in the second ultrasonic guided wave frequency domain signal; S4, determining a second longitudinal waveguide nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency; S5, determining whether the number of the second longitudinal waveguide nonlinear parameters meets the preset requirements, if not, executing S6, if yes, executing S7; S6, increasing the hollow length of the hollow simulation structure, and repeating steps S1-S5; S7, fitting a plurality of second longitudinal waveguide nonlinear parameters to obtain a function of the longitudinal waveguide nonlinear parameters varying with the gap length.
3. A method for quantifying the length of grouting voids in post-tensioned concrete structures based on ultrasonic guided waves according to claim 1 or 2, characterized in that: Determining a first longitudinal waveguide nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency includes: Wherein, β1 is the first longitudinal guided wave nonlinear parameter, A1(f) is the amplitude of the first ultrasonic guided wave frequency domain at the second frequency, and A1(2f) is the amplitude of the first ultrasonic guided wave frequency domain at the third frequency.
4. A method for quantifying the length of grouting voids in post-tensioned concrete structures based on ultrasonic guided waves according to claim 1 or 2, characterized in that: The function of the longitudinal waveguide nonlinear parameters changing with the void length is: β＝β0+kl； Among them, β0 represents the nonlinear parameter in the non-void state, l represents the void length value, and k is the slope of the fitting equation, which represents the proportional coefficient of the nonlinear parameter changing with the void length.
5. The method for quantifying the length of grouting voids in post-tensioned concrete structures based on ultrasonic guided waves according to claim 2, characterized in that: The target material is any one of pearl cotton, low-density foam and airbag.
6. A method for quantifying the length of grouting voids in post-tensioned concrete structures based on ultrasonic guided waves according to claim 1 or 2, characterized in that: An ultrasonic guided wave sensor is used to collect ultrasonic guided wave signals at both ends of the cross section of the steel strand in the target post-tensioned prestressed concrete structure under the excitation signal in a one-transmit-one-receive manner, wherein the ultrasonic guided wave sensor includes an excitation sensor and a receiving sensor. The excitation sensor is used to convert the electrical signal into an ultrasonic guided wave signal and transmit it to the steel strand in the target post-tensioned prestressed concrete structure, and the receiving sensor is used to receive the ultrasonic guided wave signal after propagation through the steel strand.
7. A device for quantifying the length of grouting voids in post-tensioned prestressed concrete structures based on ultrasonic guided waves, characterized in that: include: A signal acquisition module, used to use a signal with a center frequency of a first frequency as an excitation signal, and to acquire ultrasonic guided wave signals of cross sections at both ends of a steel strand in a target post-tensioned prestressed concrete structure under the excitation signal; A Fourier transform module, used for converting the ultrasonic guided wave signals of the cross sections of the steel strands at both ends of the target post-tensioned prestressed concrete structure from the time domain to the frequency domain by using a fast Fourier transform, so as to obtain a first ultrasonic guided wave frequency domain signal; an amplitude determination module, used to determine the amplitude at the second frequency and the amplitude at the third frequency in the first ultrasonic guided wave frequency domain signal, wherein the third frequency is the second harmonic of the second frequency; A longitudinal waveguide nonlinear parameter determination module, used to determine a first longitudinal waveguide nonlinear parameter according to the amplitude at the second frequency and the amplitude at the third frequency; The void length determination module is used to input the first longitudinal waveguide nonlinear parameter into a predetermined function of the longitudinal waveguide nonlinear parameter varying with the void length, so as to determine the grouting void length in the target post-tensioned prestressed concrete structure.
8. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the steps of the method for quantifying the void length of grouting in a post-tensioned concrete structure based on ultrasonic guided waves as described in any one of claims 1 to 6.
9. A computer storage medium having computer instructions stored thereon, characterized in that: When the instruction is executed by the processor, the steps of the method for quantifying the void length of grouting in a post-tensioned concrete structure based on ultrasonic guided waves as described in any one of claims 1-6 are implemented.