A method for detecting the integrity of pipe piles based on low-strain transmission waves

Abstract

The present invention discloses a pipe pile integrity detection method based on low-strain transmission waves, comprising: calculating and determining the pile-soil stiffness ratio and determining the transmission wave attenuation factor of the pipe pile to be tested; constructing an excitation hammer parameter prediction model to determine the excitation hammer parameters of the pipe pile to be tested; obtaining the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld; calculating the ratio of the amplitude of the incident wave above the weld to the amplitude of the transmitted wave through the weld to identify the welding quality of the pipe pile joint; calculating the maximum value of the total energy transmittance to identify the welding quality of the pipe pile joint; constructing a pipe pile welding defect type identification model to identify the pipe pile welding defect type; and determining management measures for the pipe pile joint based on the welding quality judgment result of the pipe pile joint. By combining low-strain transmission wave detection technology with intelligent data processing methods, the limitations of the traditional low-strain method in the case of long piles or uneven pile bodies are effectively overcome, and the accuracy and reliability of pipe pile detection are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering detection, and in particular to a method for detecting the integrity of pipe piles based on low-strain transmission waves. Background Art

[0002] With the continuous development of engineering construction, pipe piles, as important components in foundation engineering, are widely used in various large-scale projects, including urban construction, bridges, and dams. Especially in complex geological environments, the integrity and bearing capacity of pipe piles directly impact the safety and stability of the project. To ensure the construction quality of pipe piles, rapid and accurate testing of their integrity has become a crucial task in engineering construction. Among existing pile inspection technologies, the low-strain method has become a common method in the market due to its ease of operation, low cost, and applicability to large-scale inspections. This method uses an exciter to vibrate the pile top and measures the stress wave signal propagating from the pile body to the pile top, thereby inferring defects and unevenness in the pile body and assessing the pile's structural integrity. The low-strain method is primarily applicable to short piles or those with relatively uniform pile bodies. It can quickly provide a preliminary assessment of pile construction quality and is widely used in engineering quality surveys. However, the low-strain method has certain limitations in practical application. In particular, for long piles or those with uneven cross-sections, the size effect of the pile body and a low pile-to-soil stiffness ratio can lead to multiple reflections during stress wave propagation, resulting in a complex waveform and rapid energy dissipation or premature reflection. For such piles, the traditional low-strain method struggles to accurately obtain complete stress wave signals, making it impossible to determine the reflected wave at the pile base and, consequently, to assess the integrity of the entire pile. Especially in the case of long piles or in soft soils, the wave impedance of the pile varies significantly, often affecting the measurement results of traditional methods. This results in inaccurate results that fail to fully reflect the health of the pile. Therefore, while the low-strain method is widely used, the accuracy and comprehensiveness of its test results are still constrained by geological conditions, pile morphology, and construction quality. In this context, a more precise technical approach that overcomes the limitations of the traditional low-strain method is needed to improve the integrity assessment capabilities of long and complex piles. Summary of the Invention

[0003] The present invention addresses the problems existing in the above-mentioned prior art and provides a method for detecting the integrity of pipe piles based on low-strain transmission waves, which mainly includes:

[0004] Based on the cross-sectional area and length of the inspected pile, the pile-soil stiffness ratio is calculated and determined, and the transmission wave attenuation factor of the inspected pile is determined;

[0005] Based on the pipe pile weld position and transmission wave attenuation factor data, a vibration hammer parameter prediction model is constructed to determine the vibration hammer parameters that provide the best transmission wave signal reception effect for the inspected pipe pile.

[0006] Based on the weld position of the inspected pipe pile, hydrophones are placed vertically at preset positions with equal spacing above and below the weld, and the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld are obtained;

[0007] The welding quality of the pipe pile joint is identified by calculating the ratio of the incident wave amplitude on the upper part of the weld to the transmitted wave amplitude through the weld.

[0008] If the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, the maximum value of the total energy transmittance is determined based on the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld. The weld quality of the pipe pile joint is then identified in combination with the measured energy transmittance.

[0009] Through the complete time domain velocity signal of the general welding quality of the pipe pile joint, the spectral characteristics of the velocity signal are extracted, and a pipe pile welding defect type recognition model is constructed to identify the pipe pile welding defect type;

[0010] Based on the welding quality judgment results of the pipe pile joint area, the management measures for the pipe pile joint area are determined.

[0011] Furthermore, the method of calculating and determining the pile-soil stiffness ratio based on the cross-sectional area and length of the inspected pile and determining the transmission wave attenuation factor of the inspected pile includes:

[0012] Obtain the cross-sectional area and length of the inspected pile through the pile integrity test project file, and use the pile stiffness formula , determine the pile stiffness ,in, is the elastic modulus of the pile material, A is the cross-sectional area of ​​the pile, and L is the length of the pile. Based on the geological survey data, the elastic modulus of the soil around the pile is obtained, and the soil stiffness formula is used. , determine the soil stiffness ,in, is the elastic modulus of the soil, is the load-bearing area of ​​the soil layer around the pile, which is equal to the contact area of ​​the soil around the pile. is the effective length of the soil, which is equal to the depth of the pile body or the depth of the pile body contacting the soil layer; according to the stiffness of the pipe pile and the stiffness of the soil, the pile-soil stiffness ratio is determined ; Based on the pile-soil stiffness ratio, the transmission wave attenuation factor formula is used , determine the transmission wave attenuation factor of the pile to be tested , and store the transmission wave attenuation factor of the pipe pile in the pipe pile monitoring database, where is a constant related to soil type and wave propagation characteristics, obtained through experiments or numerical simulations; n is the interaction coefficient, a constant used to describe the interaction strength between piles and soil, obtained through experiments or numerical simulations.

[0013] Furthermore, the method of constructing a vibration hammer parameter prediction model based on the pipe pile weld position and the transmitted wave attenuation factor data to determine the vibration hammer parameters that provide the best reception effect of the transmitted wave signal of the inspected pipe pile includes:

[0014] Through the pipe pile monitoring database, the historical pipe pile weld position and transmission wave attenuation factor data are obtained, and the vibration hammering parameters that achieve the best transmission wave signal reception effect of the pipe pile are marked. A recurrent neural network is used for model training to construct a vibration hammering parameter prediction model. The vibration hammering parameters include hammering force, number of hammerings, and hammer head material. According to the length of the inspected pipe pile, the weld position of the inspected pipe pile is determined, and the transmission wave attenuation factor is obtained. The vibration hammering parameter prediction model is used to determine the vibration hammering parameters that achieve the best transmission wave signal reception effect of the inspected pipe pile.

[0015] Furthermore, based on the weld position of the inspected pipe pile, the hydrophones are vertically arranged at preset positions with equal spacing above and below the weld, and the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld are obtained, including:

[0016] The cavity of the inspected pipe pile is filled with water. The lowering depth of the hydrophone is adjusted according to the position of the weld of the inspected pipe pile, and the hydrophones are vertically arranged and placed at preset positions with equal spacing above and below the weld; based on the excitation hammer parameters that provide the best reception effect of the transmitted wave signal, the center of the top of the inspected pipe pile is hammered, and a transient excitation force is applied downward along the axis of the pile body; the complete time-domain velocity signal is obtained through the hydrophone above the weld, and the average value of the first-wave peak amplitude of each hydrophone velocity signal is calculated as the incident wave amplitude above the weld; the complete time-domain velocity signal is obtained through the hydrophone below the weld, and the average value of the first-wave peak amplitude of each hydrophone velocity signal is calculated as the transmitted wave amplitude through the weld.

[0017] Furthermore, the method of identifying the welding quality of the pipe pile connection part by calculating the ratio of the incident wave amplitude on the upper part of the weld to the transmitted wave amplitude through the weld includes:

[0018] Through the pile body integrity test project file, the cross-sectional area and material density of the inspected pile are obtained, and the pile body wave impedance calculation formula is used , determine the pile wave impedance Z of the inspected pile, where: is the material density of the pile, c is the stress wave propagation velocity, and A is the cross-sectional area of ​​the pile. According to the amplitude of the incident wave on the upper part of the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the incident wave amplitude on the upper part of the weld, is the amplitude of the transmitted wave through the weld, is the incident velocity amplitude of the pipe pile above the weld, is the amplitude of the transmission velocity from the weld interface to the pipe pile below the weld. The wave impedance of the pipe pile above the weld and the pipe pile below the weld are the same, both , is the wave impedance at the weld interface; if , it means that the welding quality of the pipe pile joint is extremely high. , it means that the welding quality of the pipe pile joint is extremely poor, and the other values ​​mean that the welding quality of the pipe pile joint is average.

[0019] Furthermore, if the wave impedances of the pipe pile above the weld and the pipe pile below the weld are different, the maximum value of the total energy transmittance is determined based on the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, and the welding quality of the pipe pile joint is identified in combination with the measured energy transmittance, including:

[0020] If the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, then according to the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the amplitude of the transmitted wave from the weld interface to the lower part of the pile, is the wave impedance of the pipe pile above the weld, is the wave impedance of the welding material, is the wave impedance of the pipe pile below the weld; according to the three-layer medium model, the total energy transmittance is obtained ,right Take the derivative and set it to zero to determine the maximum value of the total energy transmittance ; Based on the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, use the formula , calculate the measured energy transmittance ;like and If the difference is 0, it means that the welding quality of the pipe pile joint is extremely high. and If the difference is less than the preset difference threshold, it means that the welding quality of the pipe pile joint is average. and If the difference is greater than the preset difference threshold, it means that the welding quality of the pipe pile joint is extremely poor.

[0021] Furthermore, the method extracts the spectral characteristics of the velocity signal from the complete time domain velocity signal of the general welding quality of the pipe pile joint portion, constructs a pipe pile welding defect type identification model, and identifies the pipe pile welding defect type, including:

[0022] Through the hydrophone on the upper part of the weld, a complete time domain velocity signal of the general welding quality of the pipe pile joint is obtained. The short-time Fourier transform algorithm is used to convert the time domain signal of the velocity signal into frequency domain data, and the spectral characteristics of the velocity signal are extracted and saved to the pipe pile monitoring database. The spectral characteristics include frequency, frequency peak and amplitude; through the pipe pile monitoring database, the historical spectral characteristics of the pipe pile are obtained, and the welding defect types of the pipe pile are marked. The recurrent neural network is used for model training to construct a pipe pile welding defect type recognition model. The welding defect types of pipe piles include weld cracks, uneven welds, pores or slag inclusions; based on the real-time acquired pipe pile spectral characteristics, the pipe pile welding defect type recognition model is used to identify the pipe pile welding defect type.

[0023] Furthermore, the management measures for the pipe pile connection part are determined based on the welding quality judgment result of the pipe pile connection part, including:

[0024] Based on the judgment results of the welding quality of the pipe pile joints and the pipe pile joints, the management measures for the pipe pile joints are determined; if the welding quality of the pipe pile joints is extremely high, the welding quality of the pipe pile joints is regularly monitored according to the preset time intervals; if the welding quality of the pipe pile joints is average, local repairs are performed in the weld area according to the type of pipe pile welding defects, including repair welding, grinding or cleaning of the local area; if the welding quality of the pipe pile joints is extremely poor, pipe pile repair measures are taken to repair the pipe piles, and the welding quality of the pipe pile joints is inspected again after the pipe piles are repaired until the quality of the joints meets the standard requirements. Pipe pile repair measures include re-welding, reinforcement or replacement of damaged parts.

[0025] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0026] The present invention provides a method for testing the integrity of pipe piles based on low-strain transmitted waves. By calculating the pile-to-soil stiffness ratio of the pipe pile and determining the transmitted wave attenuation factor, the method can more accurately assess the structural properties of the pile body. Based on the transmitted wave attenuation factor and weld location, the method constructs an excitation hammer parameter prediction model, optimizing the selection of excitation parameters to maximize the reception of the transmitted wave signal and ensure high-quality test data. During the testing process, the vertical arrangement of hydrophones and the precise measurement of the incident and transmitted wave amplitudes above and below the weld enable accurate assessment of the weld quality at the pipe pile joint. In the weld quality assessment, the method specifically considers the wave impedance difference between the pipe piles above and below the weld. By analyzing the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, the maximum total energy transmittance can be determined. This maximum value is then compared with the measured energy transmittance to accurately identify the weld quality at the pipe pile joint. This method ensures efficient identification of welding defects, particularly in the presence of inconsistent wave impedances, improving the accuracy of weld quality assessment. Furthermore, the present invention utilizes spectral feature extraction and a welding defect type identification model to automatically identify pipe pile welding defect types, significantly improving the automation level of defect detection and reducing human error. This method offers significant advantages in improving pipe pile inspection accuracy, enhancing management efficiency, and reducing project risks. It can provide more accurate quality assurance for projects and ensure the long-term safe operation of infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a method for detecting the integrity of pipe piles based on low-strain transmission waves according to the present invention;

[0028] Figure 2 Schematic diagram of a method for detecting the integrity of pipe piles based on low-strain transmission waves according to the present invention;

[0029] Figure 3 This is another schematic diagram of a method for detecting the integrity of pipe piles based on low-strain transmission waves according to the present invention. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1-Figure 3 In this embodiment, a method for detecting the integrity of a pipe pile based on low-strain transmission waves may specifically include:

[0032] Step S101 : calculating and determining the pile-soil stiffness ratio based on the cross-sectional area and length of the inspected tubular pile, and determining the transmission wave attenuation factor of the inspected tubular pile.

[0033] Obtain the cross-sectional area and length of the inspected pile through the pile integrity test project file, and use the pile stiffness formula , determine the pile stiffness ,in, is the elastic modulus of the pile material, A is the cross-sectional area of ​​the pile, and L is the length of the pile. Based on the geological survey data, the elastic modulus of the soil around the pile is obtained and the soil stiffness formula is used. , determine the soil stiffness ,in, is the elastic modulus of the soil, is the load-bearing area of ​​the soil layer around the pile, which is equal to the contact area of ​​the soil around the pile. The effective length of the soil is equal to the depth of the pile body or the depth of the pile body contacting the soil layer. According to the stiffness of the pipe pile and the stiffness of the soil, the pile-soil stiffness ratio is determined. According to the pile-soil stiffness ratio, the transmission wave attenuation factor formula is used , determine the transmission wave attenuation factor of the pile to be tested , and store the transmission wave attenuation factor of the pipe pile in the pipe pile monitoring database, where is a constant related to soil type and wave propagation characteristics, obtained through experiments or numerical simulations; n is the interaction coefficient, a constant used to describe the interaction strength between piles and soil, obtained through experiments or numerical simulations.

[0034] For example, there is a pipe pile with a cross-sectional area of ​​0.3m 2 , length is 20m, elastic modulus of pile material Through the pile stiffness formula , determine the pile stiffness ,in, is the elastic modulus of the pile material, A is the cross-sectional area of ​​the pile, and L is the length of the pile. The elastic modulus of the soil around the pile is obtained based on geological survey data. If the elastic modulus of the soil is , the contact area of ​​the soil around the pile is 0.4m 2 , the effective length is 15m, according to the soil stiffness formula , calculate the soil stiffness as ,in, is the elastic modulus of the soil, is the load-bearing area of ​​the soil layer around the pile, which is approximately the contact area of ​​the soil around the pile. The effective length of the soil is equal to the depth of the pile body or the depth of the pile body contacting the soil layer. According to the stiffness of the pipe pile and the stiffness of the soil, the pile-soil stiffness ratio is calculated. According to the pile-soil stiffness ratio, the transmission wave attenuation factor formula is used , determine the transmission wave attenuation factor of the pile to be tested ,in, is a constant related to soil type and wave propagation characteristics, obtained through experiments or numerical simulations, and n is the interaction coefficient, a constant used to describe the interaction strength between piles and soil, obtained through experiments or numerical simulations. , , then the transmission wave attenuation factor is calculated and the transmission wave attenuation factor of the pile Stored in the pile monitoring database.

[0035] Step S102 : constructing an excitation hammer parameter prediction model based on the pipe pile weld position and the transmitted wave attenuation factor data, and determining the excitation hammer parameters that provide the best reception effect of the transmitted wave signal of the inspected pipe pile.

[0036] The historical data on pile weld locations and transmitted wave attenuation factors were obtained from the pile monitoring database. The vibration hammering parameters that optimally received the transmitted wave signal were annotated. A recurrent neural network was used for model training to construct a prediction model for the vibration hammering parameters, which included hammer force, number of blows, and hammer head material. The weld locations of the inspected piles were determined based on their lengths, and the transmitted wave attenuation factors were obtained. Using the vibration hammering parameter prediction model, the vibration hammering parameters that optimally received the transmitted wave signal were determined.

[0037] For example, data analysis shows that the transmission wave signal reception effect of pipe piles is closely related to the vibration hammering parameters, which include hammering force, number of hammerings, and hammer head material. The pipe pile monitoring database contains the weld positions and transmission wave attenuation factor data of multiple pipe piles. Through the pipe pile monitoring database, different vibration hammering parameters and corresponding transmission wave signal reception effects are obtained. For example, a pipe pile with a length of 30m, welds located at the 10th and 20th meters of the pile body, and a transmission wave attenuation factor of 0.5m -1 . The transmission wave signal reception effect in the historical data is matched with the vibration hammer parameters, and the vibration hammer parameter combination with the best reception effect is marked. For example, on this pipe pile, the vibration hammer force is set to 1000N, the number of hammering is 50 times, and the hammer head is made of steel, the signal reception effect is excellent. These data are input into the recurrent neural network for training, and a vibration hammer parameter prediction model is constructed. Through multiple trainings, the model has learned to predict new vibration hammer parameters based on the weld position of the pipe pile, the transmission wave attenuation factor, and the historical data of the vibration hammer parameters. In actual applications, if another pipe pile with a length of 25m is to be tested, and the weld position of the pipe pile is at the 8th and 18th meters. Through measurement, it is found that the transmission wave attenuation factor of the pipe pile is 0.4m -1，Using the trained vibration hammer parameter prediction model, the weld position and transmitted wave attenuation factor of the pipe pile were input. Based on historical data, the vibration hammer parameter prediction model predicted that the most suitable vibration hammer parameters were a hammer force of 900N, 40 hammer blows, and a hammer head made of steel.

[0038] Step S103 , based on the weld position of the inspected pipe pile, vertically arrange hydrophones at preset positions with equal spacing above and below the weld, and obtain the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld.

[0039] The cavity of the inspected pile is filled with water. The hydrophone lowering depth is adjusted according to the weld position of the inspected pile, and the hydrophones are vertically arranged and placed at preset positions equidistant above and below the weld. Based on the excitation hammer parameters that optimize the reception of the transmitted wave signal, the center of the top of the inspected pile is hammered, applying a transient excitation force downward along the pile axis. The complete time-domain velocity signal is acquired from the hydrophone above the weld, and the average of the first-wave peak amplitudes of the velocity signals from each hydrophone is calculated as the incident wave amplitude above the weld. The complete time-domain velocity signal is acquired from the hydrophone below the weld, and the average of the first-wave peak amplitudes of the velocity signals from each hydrophone is calculated as the transmitted wave amplitude through the weld.

[0040] For example, it is necessary to test a 25m long pipe pile with one weld located at the 10th m of the pile body. In order to perform transmission wave detection, the cavity of the pipe pile is first filled with water to ensure the best wave propagation effect. According to the position of the weld, the lowering depth of the hydrophone is adjusted, and the hydrophones are arranged vertically at the preset positions above and below the weld. In order to ensure the signal quality, the hydrophones are evenly placed at the 8th, 9th, 11th and 12th m positions, that is, the hydrophones are set at equal intervals above and below each weld. According to the optimal excitation hammer parameters obtained in the previous experiment, a hammer force of 1200N, 60 hammer times, and a hammer head material of steel were selected. According to these parameters, a transient excitation force is applied downward along the axis of the pile body at the center of the pile top to excite the pipe pile to generate a transmission wave. After the excitation force acts, the transmission wave propagates through the pile body and is reflected and transmitted at the weld. During the signal acquisition phase, a complete time-domain velocity signal is acquired through a hydrophone located above the weld. If the peak amplitudes of the first wave of the signal collected by the hydrophone at the 8th and 9th meters above the weld are both 0.5 cm / s, then the amplitude of the incident wave above the weld is the average of these two peak amplitudes, i.e., the amplitude of the incident wave above the weld = 0.5 cm / s. A complete time-domain velocity signal is acquired through a hydrophone located below the weld. If the peak amplitudes of the first wave of the signal collected by the hydrophone at the 11th and 12th meters are 0.4 cm / s and 0.4 cm / s, respectively, the average of the peak amplitudes of the first wave of the hydrophone velocity signal located below the weld is calculated, yielding the amplitude of the transmitted wave through the weld = 0.4 cm / s.

[0041] Step S104, identifying the welding quality of the pipe pile connection part by calculating the ratio of the incident wave amplitude on the upper part of the weld to the transmitted wave amplitude through the weld.

[0042] Through the pile body integrity test project file, the cross-sectional area and material density of the inspected pile are obtained, and the pile body wave impedance calculation formula is used , determine the pile wave impedance Z of the inspected pile, where: is the material density of the pile, c is the stress wave propagation velocity, and A is the cross-sectional area of ​​the pile. According to the amplitude of the incident wave on the upper part of the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the incident wave amplitude on the upper part of the weld, is the amplitude of the transmitted wave through the weld, is the incident velocity amplitude of the pipe pile above the weld, is the amplitude of the transmission velocity from the weld interface to the pipe pile below the weld. The wave impedance of the pipe pile above the weld and the pipe pile below the weld are the same, both , is the wave impedance at the weld interface. , it means that the welding quality of the pipe pile joint is extremely high. , it means that the welding quality of the pipe pile joint is extremely poor, and the other values ​​mean that the welding quality of the pipe pile joint is average.

[0043] For example, through the pile body integrity test project file, it is obtained that the inspected pile is a 30m long concrete pile, the upper pile L1 is 15m long, the lower pile L2 is 15m long, and the cross-sectional area A=0.1473m 2 , material density ρ = 2.6t / m 3 , stress wave propagation velocity c = 4200m / s, wave impedance Z = ρcA = 1608kN·s / m in the pile body. According to the amplitude of the incident wave on the upper part of the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes Therefore, after the first transmission, the transmission velocity amplitude from the upper pipe pile of the weld to the weld interface is After the second transmission, the transmission velocity amplitude from the weld interface to the pipe pile below the weld is , at this time , where the wave impedance of the pipe pile above the weld and the pipe pile below the weld are the same, both , is the wave impedance at the weld interface, then the integrity coefficient of the stress wave transmitted from the pipe pile L1 into the welding material , and then the integrity coefficient of the pipe pile L2 transmitted by the welding material is When the welding quality of the pipe pile joint is extremely high, the weld can be regarded as a complete steel material, and the upper and lower pipe piles are completely connected. , When the welding quality of the pipe pile joint is extremely poor, the weld can be regarded as mud, and the upper and lower pipe piles are completely disconnected. , The other values ​​indicate that the connection condition is between fully connected and fully disconnected, and the welding quality of the pipe pile connection parts is average.

[0044] Step S105: If the wave impedances of the pipe pile above the weld and the pipe pile below the weld are different, the maximum value of the total energy transmittance is determined based on the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, and the welding quality of the pipe pile joint is identified in combination with the measured energy transmittance.

[0045] If the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, then according to the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the amplitude of the transmitted wave from the weld interface to the lower part of the pile, is the wave impedance of the pipe pile above the weld, is the wave impedance of the welding material, is the wave impedance of the pipe pile below the weld. According to the three-layer medium model, the total energy transmittance is obtained ,right Take the derivative and set it to zero to determine the maximum value of the total energy transmittance According to the incident wave amplitude on the upper part of the weld and the transmitted wave amplitude through the weld, use the formula , calculate the measured energy transmittance .like and If the difference is 0, it means that the welding quality of the pipe pile joint is extremely high. and If the difference is less than the preset difference threshold, it means that the welding quality of the pipe pile joint is average. and If the difference is greater than the preset difference threshold, it means that the welding quality of the pipe pile joint is extremely poor.

[0046] For example, if the wave impedance of the upper pipe pile and the lower pipe pile of the weld are different, the length of the upper pipe pile L3 is 15m and the cross-sectional area is 0.1473 m 2 , material density is 2.6 t / m 3 , the stress wave velocity is 4200m / s. The length of the lower pipe pile L4 is 15m, and the cross-sectional area is 0.1100 m 2, material density is 2.6 t / m 3 , the stress wave velocity is 4200 m / s. According to the material parameters, the wave impedance of the upper pipe pile is 1601.58 kN·s / m, and the wave impedance of the lower pipe pile is 1200.72 kN·s / m. Based on the formula , calculate the ratio of two amplitudes . Incident wave When transmitting from the upper pipe pile to the weld, there is a transmission velocity amplitude from the upper pipe pile of the weld to the weld interface. . When the wave is transmitted from the weld to the lower pipe pile, the amplitude of the wave transmitted from the weld interface to the lower part of the pipe pile is , so the total transmittance is ,in, is the wave impedance of the pipe pile above the weld, is the wave impedance of the welding material, is the wave impedance of the pipe pile below the weld, impedance ratio , According to the three-layer medium model, the total energy transmittance To maximize , need to Taking the derivative and setting it to zero, we get When the total energy transmittance is the largest, the maximum value of the total energy transmittance is determined. If the hydrophone actually measures the velocity amplitude of the upper part of the weld , velocity amplitude at the lower part of the weld , using the formula , calculate the measured energy transmittance . is 0.31, is 0.96, and The difference is 0.65, which is greater than the preset difference threshold of 0.1, indicating that the welding quality of the pile joint is extremely poor. and The difference is 0.05, which is less than the preset difference threshold of 0.1, indicating that the welding quality of the pile joint is average. and If the difference is 0, it means that the welding quality of the pipe pile joints is extremely high.

[0047] Step S106 , extracting the frequency spectrum characteristics of the velocity signal through the complete time domain velocity signal of the general welding quality of the pipe pile joint part, constructing a pipe pile welding defect type identification model, and identifying the pipe pile welding defect type.

[0048] A hydrophone located above the weld seam is used to obtain a complete time-domain velocity signal indicating the general weld quality at the pipe pile joint. A short-time Fourier transform algorithm is used to convert the time-domain velocity signal into frequency-domain data. The spectral characteristics of the velocity signal, including frequency, frequency peak, and amplitude, are extracted and saved to the pipe pile monitoring database. The historical spectral characteristics of the pipe piles are obtained from the pipe pile monitoring database, and the types of weld defects associated with the pipe piles are annotated. A recurrent neural network is used for model training to construct a pipe pile welding defect type recognition model. Pipe pile welding defect types include, but are not limited to, weld cracks, uneven welds, porosity, or slag inclusions. Based on the real-time spectral characteristics of the pipe piles, the pipe pile welding defect type recognition model is used to identify the type of weld defect associated with the piles.

[0049] For example, a pipe pile joint was inspected for weld quality. The weld quality of the pipe pile was generally average. A hydrophone was placed above the weld, successfully acquiring complete time-domain velocity signals reflecting the wave propagation characteristics of the weld. A short-time Fourier transform algorithm was used to convert these time-domain signals into frequency-domain data, extracting spectral features. The main features extracted from the spectrum included a frequency of 500 Hz, a peak frequency of 520 Hz, and an amplitude of 0.8 m / s. These spectral features were then stored in a pipe pile monitoring database, which also contains spectral features from previous pipe piles. The database also contains the spectral features of each pipe pile, along with the type of weld defect for each pipe pile. These defects include weld cracks, uneven welds, pores, or slag inclusions. Through the pipe pile monitoring database, the historical spectrum characteristics of the pipe piles are obtained, and the welding defect types of the pipe piles are marked. The recurrent neural network is used to train the pipe pile welding defect types and construct a pipe pile welding defect type recognition model. After training, the pipe pile welding defect type recognition model can automatically identify the welding defect type of the pipe pile based on the spectrum characteristics obtained in real time. For example, when we conduct real-time inspection of the welding parts of the pipe piles on site, new spectrum characteristics are obtained again through the hydrophone. The frequency of the real-time signal is 505Hz, the frequency peak is 515Hz, and the amplitude is 0.75m / s. These data are input into the pipe pile welding defect type recognition model, and the welding defect type of the pipe pile is identified as uneven weld.

[0050] Step S107, determining management measures for the pipe pile connection part according to the welding quality judgment result of the pipe pile connection part.

[0051] Based on the judgment results of the welding quality of the pipe pile joints and in combination with the pipe pile joints, the management measures for the pipe pile joints are determined. If the welding quality of the pipe pile joints is extremely high, the welding quality of the pipe pile joints is regularly monitored according to the preset time intervals. If the welding quality of the pipe pile joints is average, local repairs are performed in the weld area according to the type of pipe pile welding defects, including but not limited to repair welding, grinding or cleaning of the local area. If the welding quality of the pipe pile joints is extremely poor, pipe pile repair measures are taken to repair the pipe piles, and the welding quality of the pipe pile joints is re-tested after the pipe piles are repaired until the quality of the joints meets the standard requirements. Pipe pile repair measures include re-welding, reinforcement or replacement of damaged parts.

[0052] For example, the welding quality of the joint of a pipe pile is evaluated. The pile length is 30 meters, and the welding positions are at the 10th and 20th meters of the pile body. According to the previous test results, the welding quality was evaluated as general, and the spectrum analysis found that there was slight unevenness in the welding area. In this case, the management measures for the joint of the pipe pile will be adjusted according to the specific type of welding defects. Since the welding quality was evaluated as general, the spectrum feature analysis found that the welding was uneven, which was manifested in slight fluctuations in the frequency peak and amplitude. In this case, local repairs were carried out in the weld area. The repair work included re-welding the weld area, especially at the 10th and 20th meter welding positions, to ensure the uniformity and integrity of the weld. In addition, the local area needs to be polished to smooth the weld surface and clean up the pores and impurities that may be generated during the welding process, thereby improving the welding quality. If the weld quality of the pile joint is rated as very high, regular monitoring will be carried out according to pre-set intervals. This may mean monthly or bi-weekly inspections of the pile joint to monitor for any new cracks or uneven welds. In cases where the weld quality is rated as extremely poor, more drastic repair measures will be required. If an inspection reveals that the weld quality is so poor that the strength of the pile joint is far below the standard requirements, we will conduct extensive repairs on the pile. This may include completely re-welding the pile joint, re-welding, reinforcing or replacing the damaged area. After the repair, detailed weld quality inspections will be carried out again to ensure that the repaired pile joint meets the standards and is suitable for normal use.

[0053] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the concept of this application. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for detecting the integrity of pipe piles based on low-strain transmission waves, characterized in that: The method comprises: Based on the cross-sectional area and length of the inspected pile, the pile-soil stiffness ratio is calculated and determined, and the transmission wave attenuation factor of the inspected pile is determined; Based on the pipe pile weld position and transmission wave attenuation factor data, a vibration hammer parameter prediction model is constructed to determine the vibration hammer parameters that provide the best transmission wave signal reception effect for the inspected pipe pile. Based on the weld position of the inspected pipe pile, hydrophones are placed vertically at preset positions with equal spacing above and below the weld, and the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld are obtained; The welding quality of the pipe pile joint is identified by calculating the ratio of the incident wave amplitude on the upper part of the weld to the transmitted wave amplitude through the weld. If the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, the maximum value of the total energy transmittance is determined based on the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld. The weld quality of the pipe pile joint is then identified in combination with the measured energy transmittance. Through the complete time domain velocity signal of the general welding quality of the pipe pile joint, the spectral characteristics of the velocity signal are extracted, and a pipe pile welding defect type recognition model is constructed to identify the pipe pile welding defect type; Determine the management measures for the pipe pile joints based on the welding quality judgment results of the pipe pile joints; The method of calculating and determining the pile-soil stiffness ratio based on the cross-sectional area and length of the inspected pile and determining the transmission wave attenuation factor of the inspected pile includes: Obtain the cross-sectional area and length of the inspected pile through the pile integrity test project file, and use the pile stiffness formula , determine the pile stiffness ,in, is the elastic modulus of the pile material, A is the cross-sectional area of ​​the pile, and L is the length of the pile. Based on the geological survey data, the elastic modulus of the soil around the pile is obtained, and the soil stiffness formula is used. , determine the soil stiffness ,in, is the elastic modulus of the soil, is the load-bearing area of ​​the soil layer around the pile, which is equal to the contact area of ​​the soil around the pile. is the effective length of the soil, which is equal to the depth of the pile body or the depth of the pile body contacting the soil layer; according to the stiffness of the pipe pile and the stiffness of the soil, the pile-soil stiffness ratio is determined ; Based on the pile-soil stiffness ratio, the transmission wave attenuation factor formula is used , determine the transmission wave attenuation factor of the pile to be tested , and store the transmission wave attenuation factor of the pipe pile in the pipe pile monitoring database, where is a constant related to soil type and wave propagation characteristics, obtained through experiments or numerical simulations; n is the interaction coefficient, a constant used to describe the interaction strength between piles and soil, obtained through experiments or numerical simulations; The method of identifying the welding quality of the pipe pile connection part by calculating the ratio of the incident wave amplitude on the upper part of the weld to the transmitted wave amplitude through the weld includes: Through the pile body integrity test project file, the cross-sectional area and material density of the inspected pile are obtained, and the pile body wave impedance calculation formula is used , determine the pile wave impedance Z of the inspected pile, where: is the material density of the pile, c is the stress wave propagation velocity, and A is the cross-sectional area of ​​the pile. According to the amplitude of the incident wave on the upper part of the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the incident wave amplitude on the upper part of the weld, is the amplitude of the transmitted wave through the weld, is the incident velocity amplitude of the pipe pile above the weld, is the amplitude of the transmission velocity from the weld interface to the pipe pile below the weld; if , it means that the welding quality of the pipe pile joint is extremely high. , it means that the welding quality of the pipe pile joint is extremely poor, and the other values ​​mean that the welding quality of the pipe pile joint is average; Wherein, if the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, the maximum value of the total energy transmittance is determined based on the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, and the welding quality of the pipe pile joint is identified in combination with the measured energy transmittance, including: If the wave impedance of the pipe pile above the weld is different from that of the pipe pile below the weld, then according to the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld, based on the formula , calculate the ratio of two amplitudes ,in, is the amplitude of the transmitted wave from the weld interface to the lower part of the pile; according to the three-layer medium model, the total energy transmittance is obtained ,right Take the derivative and set it to zero to determine the maximum value of the total energy transmittance ; Based on the incident wave amplitude above the weld and the transmitted wave amplitude through the weld, use the formula , calculate the measured energy transmittance ;like and If the difference is 0, it means that the welding quality of the pipe pile joint is extremely high. and If the difference is less than the preset difference threshold, it means that the welding quality of the pipe pile joint is average. and If the difference is greater than the preset difference threshold, it means that the welding quality of the pipe pile joint is extremely poor.

2. The method according to claim 1, wherein The method of constructing a vibration hammer parameter prediction model based on the pipe pile weld position and the transmitted wave attenuation factor data to determine the vibration hammer parameters that provide the best reception effect of the transmitted wave signal of the inspected pipe pile includes: Through the pipe pile monitoring database, the historical pipe pile weld position and transmission wave attenuation factor data are obtained, and the vibration hammering parameters that achieve the best transmission wave signal reception effect of the pipe pile are marked. A recurrent neural network is used for model training to construct a vibration hammering parameter prediction model. The vibration hammering parameters include hammering force, number of hammerings, and hammer head material. According to the length of the inspected pipe pile, the weld position of the inspected pipe pile is determined, and the transmission wave attenuation factor is obtained. The vibration hammering parameter prediction model is used to determine the vibration hammering parameters that achieve the best transmission wave signal reception effect of the inspected pipe pile.

3. The method according to claim 1, wherein Based on the weld position of the inspected pipe pile, the hydrophones are vertically arranged and placed at preset positions with equal spacing above and below the weld, and the amplitude of the incident wave above the weld and the amplitude of the transmitted wave through the weld are obtained, including: The cavity of the inspected pipe pile is filled with water. The lowering depth of the hydrophone is adjusted according to the position of the weld of the inspected pipe pile, and the hydrophones are vertically arranged and placed at preset positions with equal spacing above and below the weld; based on the excitation hammer parameters that provide the best reception effect of the transmitted wave signal, the center of the top of the inspected pipe pile is hammered, and a transient excitation force is applied downward along the axis of the pile body; the complete time-domain velocity signal is obtained through the hydrophone above the weld, and the average value of the first-wave peak amplitude of each hydrophone velocity signal is calculated as the incident wave amplitude above the weld; the complete time-domain velocity signal is obtained through the hydrophone below the weld, and the average value of the first-wave peak amplitude of each hydrophone velocity signal is calculated as the transmitted wave amplitude through the weld.

4. The method according to claim 1, wherein The method extracts the spectral characteristics of the velocity signal from the complete time domain velocity signal of the general welding quality of the pipe pile joint portion, constructs a pipe pile welding defect type identification model, and identifies the pipe pile welding defect type, including: Through the hydrophone on the upper part of the weld, a complete time domain velocity signal of the general welding quality of the pipe pile joint is obtained. The short-time Fourier transform algorithm is used to convert the time domain signal of the velocity signal into frequency domain data, and the spectral characteristics of the velocity signal are extracted and saved to the pipe pile monitoring database. The spectral characteristics include frequency, frequency peak and amplitude; through the pipe pile monitoring database, the historical spectral characteristics of the pipe pile are obtained, and the welding defect types of the pipe pile are marked. The recurrent neural network is used for model training to construct a pipe pile welding defect type recognition model. The welding defect types of pipe piles include weld cracks, uneven welds, pores or slag inclusions; based on the real-time acquired pipe pile spectral characteristics, the pipe pile welding defect type recognition model is used to identify the pipe pile welding defect type.

5. The method according to claim 1, wherein The management measures for the pipe pile connection parts are determined based on the welding quality judgment results of the pipe pile connection parts, including: Based on the judgment results of the welding quality of the pipe pile joints and the pipe pile joints, the management measures for the pipe pile joints are determined; if the welding quality of the pipe pile joints is extremely high, the welding quality of the pipe pile joints is regularly monitored according to the preset time intervals; if the welding quality of the pipe pile joints is average, local repairs are performed in the weld area according to the type of pipe pile welding defects, including repair welding, grinding or cleaning of the local area; if the welding quality of the pipe pile joints is extremely poor, pipe pile repair measures are taken to repair the pipe piles, and the welding quality of the pipe pile joints is inspected again after the pipe piles are repaired until the quality of the joints meets the standard requirements. Pipe pile repair measures include re-welding, reinforcement or replacement of damaged parts.

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