A method and device for detecting pile foundation of existing bridge based on phase difference method

Abstract

The present application relates to the field of bridge detection technology, and specifically to a method and device for detecting existing bridge pile foundations based on a phase difference method, the method comprising the following steps: obtaining a first signal and a second signal detected by an acceleration sensor set at two vertical intervals after hitting the pile foundation; finding the effective extreme value in the first signal and the second signal; obtaining the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal; determining the echo time according to the abnormal change of the periodic phase difference to determine the defect position or pile length. It can solve the problem in the prior art that the asymmetry of the excitation position and the existence of the superstructure will lead to limitations in signal feature recognition and defect differentiation.

Description

Technical Field

[0001] The present application relates to the technical field of bridge detection, and in particular to a method and device for detecting pile foundations of existing bridges based on a phase difference method. Background Art

[0002] In pile foundation integrity testing, low-strain reflection wave technology is widely used in engineering projects such as bridges, buildings and roads because of its safety, high efficiency and easy operation. As a non-destructive testing method, this technology determines the integrity of the pile foundation by applying excitation to the top of the pile and recording the reflected wave signal. The stress wave generated by the excitation propagates in the pile. When the impedance of the pile body changes (such as broken piles, shrinkage or segregation), the stress wave will be reflected back to the top of the pile. These signals are received by the acceleration sensor and analyzed on the computer. The reflected signals of different parts of the pile body can be identified, thereby evaluating the integrity of the pile body and determining the degree and location of defects.

[0003] In order to improve the detection accuracy, a multi-sensor signal receiving method is adopted. An excitation signal is applied to the top of the pile to generate stress waves, and multiple sensors are installed on the side of the pile to collect acceleration data at the same time. The average wave velocity of the pile body is calculated by the distance and response time difference between the sensors, and the effective upward stress wave is separated to accurately judge the integrity of the pile body. Compared with the traditional single sensor method, the multi-sensor method has significant advantages in identifying defects, especially in the cap pile foundation, because the sensor is installed under the cap, which effectively reduces the interference of the cap reflected wave.

[0004] Although multi-sensor detection methods have shown advantages, their signal processing and analysis still face challenges. Since multiple sensors make the signal more complex, especially when there is a superstructure, the difficulty of data analysis increases significantly. Identifying real defects and high-frequency interference in the signal requires extensive professional knowledge. Existing analysis methods have limitations in signal feature recognition and defect differentiation, which affects the reliability of result interpretation. Summary of the invention

[0005] The present application provides a method and device for detecting pile foundations of existing bridges based on a phase difference method, which can solve the problem in the prior art that the asymmetry of the excitation position and the existence of the superstructure will lead to limitations in signal feature recognition and defect differentiation.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] On the one hand, the present invention provides a method for detecting an existing bridge pile foundation based on a phase difference method, comprising the following steps:

[0008] Acquire a first signal and a second signal detected by acceleration sensors arranged at two vertical intervals after striking the pile foundation;

[0009] Find the significant extreme values ​​in the first signal and the second signal;

[0010] Obtaining a periodic phase difference between a valid extreme value in the first signal and a nearest valid extreme value in the second signal;

[0011] According to the abnormal changes in the periodic phase difference, the echo time is determined to determine the defect location or pile length.

[0012] In some optional solutions, finding the effective extreme values ​​of the first signal and the second signal includes:

[0013] Normalizing the first signal and the second signal to obtain a first normalized signal and a second normalized signal;

[0014] Extract the effective extreme values ​​in the first normalized signal and the second normalized signal.

[0015] In some optional solutions, the step of using an extreme value detection algorithm to extract effective extreme values ​​in the first normalized signal and the second normalized signal includes:

[0016] extracting preliminary extreme values ​​in the first normalized signal and the second normalized signal by adjusting a prominence threshold of an extreme value detection algorithm;

[0017] The preliminary extrema in the first normalized signal are matched with the preliminary extrema with the closest time difference in the second normalized signal as valid extrema, and the remaining preliminary extrema are deleted.

[0018] In some optional solutions, the step of extracting preliminary extreme values ​​from the first normalized signal and the second normalized signal by adjusting a prominence threshold of an extreme value detection algorithm includes:

[0019] Setting an initial prominence threshold of an extremum detection algorithm to extract extrema in the first normalized signal and the second normalized signal;

[0020] comparing the difference in the number of extreme values ​​in the first normalized signal and the second normalized signal;

[0021] When the quantitative difference is greater than the set difference threshold, the prominence threshold of the extreme value detection algorithm is adjusted, and the extreme values ​​in the first normalized signal and the second normalized signal are extracted again until the quantitative difference between the extreme values ​​in the first normalized signal and the second normalized signal is less than the set difference threshold, thereby obtaining the preliminary extreme values ​​in the first normalized signal and the second normalized signal.

[0022] In some optional solutions, matching the preliminary extreme value in the first normalized signal with the preliminary extreme value with the closest time difference in the second normalized signal as the valid extreme value, and deleting the remaining preliminary extreme values, includes:

[0023] Matching each preliminary extreme value in the first normalized signal with a preliminary extreme value in the second normalized signal with the closest time difference in chronological order, and removing or marking the preliminary extreme value set in the second normalized signal;

[0024] Until all the preliminary extreme values ​​in the first normalized signal reach the preliminary extreme values ​​in the second normalized signal, or all the preliminary extreme values ​​in the second normalized signal are removed or marked;

[0025] The preliminary extreme value in the first normalized signal and the preliminary extreme value matched in the second normalized signal are taken as the effective extreme value.

[0026] In some optional schemes, the method of obtaining the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal includes: subtracting the effective extreme value moment in each second normalized signal from the corresponding effective extreme value moment in the matching first normalized signal to obtain the periodic phase difference.

[0027] In some optional schemes, the moment corresponding to the negative value of the periodic phase difference is the echo time.

[0028] In some optional schemes, when the time corresponding to the first preliminary extreme value in the first normalized signal is later than the time corresponding to the first preliminary extreme value in the second normalized signal, the first preliminary extreme value in the first normalized signal is eliminated.

[0029] In some alternative embodiments, the extreme value is a peak or a trough.

[0030] In a second aspect, the present invention provides an existing bridge pile foundation detection device based on a phase difference method, comprising:

[0031] A signal acquisition module, which is used to acquire a first signal and a second signal detected by two acceleration sensors arranged at vertical intervals after the pile foundation is struck;

[0032] An extreme value extraction module, which is used to find the effective extreme values ​​in the first signal and the second signal;

[0033] A phase difference calculation module, which is used to obtain a periodic phase difference between a valid extreme value in the first signal and a nearest valid extreme value in the second signal;

[0034] The echo determination module is used to determine the echo time according to the abnormal change of the periodic phase difference, so as to determine the defect position or pile length.

[0035] Compared with the prior art, the advantages of the present invention are: in this scheme, the first signal and the second signal detected by the acceleration sensor set at two vertical intervals after hitting the pile foundation are obtained; the effective extreme value in the first signal and the second signal is found; the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal is obtained; according to the abnormal change of the periodic phase difference, the echo time is determined to determine the defect position or pile length; all can be used with the help of automated algorithms to realize automatic signal recognition and defect discrimination, reducing the dependence on manual analysis, greatly improving the reliability and consistency of the detection results, and without rich professional knowledge, signal feature recognition and defect differentiation can be realized, improving the versatility of the method and the recognition efficiency of pile foundation integrity identification. It can also solve the problem in the prior art that the asymmetry of the excitation position and the existence of the superstructure will cause limitations in signal feature recognition and defect differentiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 It is a flow chart of an existing bridge pile foundation detection method based on a phase difference method in an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of the operation of extracting signals by the dual-speed method in an embodiment of the present invention;

[0039] Figure 3 This is a complete waveform diagram of normalization processing in an embodiment of the present invention;

[0040] Figure 4 is a significant peak graph screened out from the first normalized signal and the second normalized signal in an embodiment of the present invention;

[0041] Figure 5 is a significant trough graph screened out from the first normalized signal and the second normalized signal in an embodiment of the present invention;

[0042] Figure 6 A periodic phase difference diagram of the peak and trough matched in an embodiment of the present invention;

[0043] Figure 7 It is a schematic diagram of an existing bridge pile foundation detection device based on the phase difference method in an embodiment of the present invention.

[0044] In the figure: 1. Bridge pier; 2. Superstructure; 3. Pile body; 4. Vibration hammer; 5. Acceleration sensor; 6. Signal collector. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0047] like Figure 1 As shown, in the first aspect, the embodiment of the present application provides a method for detecting an existing bridge pile foundation based on a phase difference method, comprising the following steps:

[0048] S1: Acquire a first signal and a second signal detected by acceleration sensors arranged at two vertical intervals after striking the pile foundation.

[0049] like Figure 2 As shown, in this example, an excitation point is set on the pile body 3, the excitation point is located below the superstructure 2, and the pier 1 is located above the superstructure 2, and two vertically spaced acceleration sensors 5, i.e., signal acquisition points, are set on the pile body 3 below the excitation point. The excitation point is struck with an excitation hammer 4, and the excitation wave propagates through the pile body 3 and is reflected at the pile end or defect position to form a reflected wave. The signal collector 6 is used to extract the signal data of the two acceleration sensors 5 and read the data. In this example, the first signal is the signal detected by the upper acceleration sensor, and the second signal is the signal detected by the lower acceleration sensor.

[0050] S2: Find the effective extreme values ​​in the first signal and the second signal.

[0051] The movement of the vehicle or other factors may also cause vibration, and the acceleration sensor 5 may also collect vibration signals. Therefore, it is necessary to remove irrelevant signals as much as possible and extract effective extreme values.

[0052] In this example, the extreme value may be a peak or a trough, and the extreme value types extracted from the first signal and the second signal correspond to each other. Of course, the peak and the trough may also be extracted.

[0053] In some optional embodiments, step S2 includes:

[0054] like Figure 3 As shown, S21: normalize the first signal and the second signal to obtain a first normalized signal and a second normalized signal.

[0055] In this example, the signal is normalized to facilitate subsequent signal analysis and defect identification.

[0056] S22: Extracting effective extreme values ​​in the first normalized signal and the second normalized signal.

[0057] Step S22 specifically includes:

[0058] S221: Extracting preliminary extreme values ​​in the first normalized signal and the second normalized signal by adjusting the prominence threshold of the extreme value detection algorithm.

[0059] A: Set the initial prominence threshold of the extremum detection algorithm to extract the extrema in the first normalized signal and the second normalized signal.

[0060] In this example, the initial prominence threshold is set based on experience, and by setting the initial prominence threshold, the extreme values ​​in the first normalized signal and the second normalized signal are preliminarily extracted.

[0061] like Figure 4 and Figure 5 As shown in the figure, the process of finding the peaks and troughs of the two signals is as follows: by using the peak detection algorithm, setting the initial prominence threshold, and detecting the peak position and amplitude in the first normalized signal and the second normalized signal respectively. Similarly, the first normalized signal and the second normalized signal are subjected to trough detection, and the trough position and amplitude are found by taking the negative value of the signal, using the same algorithm, and restoring the result to a positive value. In order to screen out significant peaks, a higher prominence threshold is set.

[0062] B: Comparison of the number of extreme values ​​in the first normalized signal and the second normalized signal.

[0063] In order to exclude the peaks and troughs caused by clutter in the first normalized signal and the second normalized signal as much as possible, the difference in the number of extreme values ​​in the first normalized signal and the second normalized signal is compared, and the peaks and troughs caused by clutter are excluded as much as possible by adjusting the prominence threshold.

[0064] C: When the quantitative difference is greater than the set difference threshold, adjust the prominence threshold of the extreme value detection algorithm, and extract the extreme values ​​in the first normalized signal and the second normalized signal again until the quantitative difference between the extreme values ​​in the first normalized signal and the second normalized signal is less than the set difference threshold, thereby obtaining the preliminary extreme values ​​in the first normalized signal and the second normalized signal.

[0065] When comparing the number difference here, when the extreme value is the peak, the number difference of the peaks in the first normalized signal and the second normalized signal is compared; when the extreme value is the trough, the number difference of the troughs in the first normalized signal and the second normalized signal is compared. When the number difference is less than the set difference threshold, it is considered that the peaks and troughs generated by the clutter have been eliminated as much as possible.

[0066] S222: Match the preliminary extreme value in the first normalized signal with the preliminary extreme value with the closest time difference in the second normalized signal as the valid extreme value, and delete the remaining preliminary extreme values.

[0067] Step S222 specifically includes:

[0068] Each preliminary extreme value in the first normalized signal is matched with a preliminary extreme value with the closest time difference in the second normalized signal in chronological order, and is removed or marked from the preliminary extreme value set in the second normalized signal.

[0069] Until all the preliminary extreme values ​​in the first normalized signal reach the preliminary extreme values ​​in the second normalized signal, or all the preliminary extreme values ​​in the second normalized signal are eliminated or marked.

[0070] Specifically, the process of finding the closest peak and trough of the second normalized signal for each peak and trough of the first normalized signal and calculating the phase difference between them is as follows: finding the closest peak of the second normalized signal for each peak of the first normalized signal, and using a logical array to track the peak usage of the second normalized signal to ensure that each peak of the second normalized signal is used only once. The same process applies to trough matching. Delete the unmatched peaks and / or troughs. The matched preliminary extreme values ​​are valid extreme values, that is, the matched preliminary peaks and preliminary troughs are valid peaks and valid troughs.

[0071] In this example, all matching results, namely effective peaks and effective troughs, are stored for subsequent analysis and graphical display. In other embodiments, only effective peaks or effective troughs may be used.

[0072] The purpose of this step is to ensure the validity of the signal, thereby ensuring the consistency and integrity of the data, and thus ensuring the accuracy and reliability of subsequent analysis.

[0073] S3: Obtain the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal.

[0074] Preferably, the effective extreme value moment in each second normalized signal is subtracted from the effective extreme value moment in the matched first normalized signal to obtain a periodic phase difference.

[0075] Specifically, the peak period phase difference is determined by calculating the time difference between the first normalized signal and the second normalized signal according to the matching peak positions; and the trough period phase difference is calculated by comparing the trough positions of the first normalized signal and the second normalized signal.

[0076] In this example, the periodic phase difference is the relative phase offset of two periodic signals with the same frequency in the time domain, that is, the time difference of the collected signals.

[0077] The phase difference can be used to accurately describe the time delay relationship between signals. At the same time, when using the dual-velocity method to detect pile foundations, by recording and analyzing the phase difference changes between the same-frequency signals received by the upper and lower sensors, the difference in signal propagation speeds in various parts of the pile body can be effectively evaluated, thereby quickly identifying the presence and location of defects in the pile bottom and pile body, significantly improving the accuracy and reliability of pile foundation detection.

[0078] S4: Determine the echo time based on the abnormal change of the periodic phase difference to determine the defect location or pile length.

[0079] In this example, the periodic phase difference of the effective peaks and troughs is plotted over time. By setting the appropriate graph properties, the images are clear and easy to read, making it easier to understand and analyze the phase difference changes between the signals. These images are saved to the specified output folder for further reference and reporting.

[0080] In this example, the time of the periodic phase difference may be the time of the corresponding extreme value of the first signal, or the time of the corresponding extreme value of the second signal.

[0081] like Figure 6 As shown, preferably, the time corresponding to the negative value of the periodic phase difference is the echo time.

[0082] Specifically, after the excitation wave is emitted from the excitation point, it propagates downward along the pile body. During the propagation process, the excitation wave first reaches the upper sensor and then reaches the lower sensor. Due to the different propagation distances of the waves, the upper sensor receives the signal earlier and the lower sensor receives the signal later, so there will be a certain phase difference between the signals received by the two sensors. When the signal does not reach the bottom of the pile, the phase difference is positive; when the excitation wave reaches the bottom of the pile and is reflected and transmitted back, the phase difference will change, usually becoming a negative value, for example Figure 6 The time point in the box is the echo time. The first time point when the phase difference changes from positive to negative is the characteristic signal point of the pile bottom or defect. Therefore, by monitoring the change of the phase difference, the position of the pile bottom can be accurately determined. If there is a defect in the pile body, the defect area will affect the propagation or reflection characteristics of the wave, resulting in an abnormal change in the phase difference, so that the position of the defect can be identified and located.

[0083] Determine the defect location or pile length based on the echo time:

[0084] Wave speed:

[0085] Pile length or defect location :

[0086] in: v is the average wave speed; is the time difference between the first wave peaks of the two signals; L 1 is the distance between the upper collection point and the top of the pile body; L 2 is the distance between the lower collection point and the top of the pile body; h is the height of the upper structure; t is the time point of the echo signal.

[0087] In this example, when the echo point calculated by echo time is not the designed pile length, the waveforms of the first signal and the second signal are compared in detail to make a more accurate judgment to determine whether the echo point is a defect or the pile body does not reach the designed pile length.

[0088] This solution can effectively deal with the signal complexity problem caused by the existence of superstructures in traditional detection methods by combining the detection method with advanced signal processing algorithms. In the data processing process, the automatic recognition and defect discrimination of signals are realized with the help of automated algorithms, which reduces the dependence on manual analysis and greatly improves the reliability and consistency of the detection results. Compared with the prior art, the present invention can more accurately separate and analyze the real defect signals and interference signals in the signal to ensure the efficiency and accuracy of data processing. In addition, the present invention generates visual images to intuitively display the signal change trend and phase difference, which helps engineering and technical personnel to quickly understand and analyze the detection results. Combining the above advantages, the present invention has broad application prospects in engineering practice, and is particularly suitable for bridge and building inspection projects with high requirements for pile foundation integrity.

[0089] In a second aspect, the present invention provides an existing bridge pile foundation detection device based on a phase difference method, comprising: a signal acquisition module, an extreme value extraction module, a phase difference calculation module and an echo determination module.

[0090] The signal acquisition module is used to obtain the first signal and the second signal detected by the acceleration sensors set at two vertical intervals after hitting the pile foundation; the extreme value extraction module is used to find the effective extreme values ​​in the first signal and the second signal; the phase difference calculation module is used to obtain the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal; the echo determination module is used to determine the echo time according to the abnormal change of the periodic phase difference, so as to determine the defect location or pile length.

[0091] Among them, the functional implementation of each module in the above-mentioned existing bridge pile foundation detection device based on the phase difference method corresponds to the various steps in the above-mentioned existing bridge pile foundation detection method based on the phase difference method. Its functions and implementation processes will not be repeated here one by one.

[0092] In a third aspect, an embodiment of the present application provides an existing bridge pile foundation detection device based on a phase difference method. The existing bridge pile foundation detection device based on a phase difference method can be a personal computer (PC), a laptop computer, a server, or other device with data processing capabilities.

[0093] Reference Figure 7 , Figure 7 The hardware structure diagram of the existing bridge pile foundation detection device based on the phase difference method involved in the embodiment of the present application is shown in FIG. In the embodiment of the present application, the existing bridge pile foundation detection device based on the phase difference method may include a processor, a memory, a communication interface and a communication bus.

[0094] The communication bus may be of any type and is used to interconnect the processor, the memory, and the communication interface.

[0095] The communication interface includes input / output (I / O) interface, physical interface and logical interface, etc., which are used to realize the interconnection of devices inside the existing bridge pile foundation detection equipment based on the phase difference method, and the interface used to realize the interconnection between the existing bridge pile foundation detection equipment based on the phase difference method and other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, a fiber optic interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[0096] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0097] The processor may be a general-purpose processor, which may call the existing bridge pile foundation detection program based on the phase difference method stored in the memory, and execute the existing bridge pile foundation detection method based on the phase difference method provided in the embodiment of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the existing bridge pile foundation detection program based on the phase difference method is called may refer to the various embodiments of the existing bridge pile foundation detection method based on the phase difference method of the present application, which will not be described in detail here.

[0098] Those skilled in the art will understand that Figure 7 The hardware structure shown in the figure does not constitute a limitation on the present application, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0099] In a fourth aspect, an embodiment of the present application also provides a computer-readable storage medium.

[0100] The computer-readable storage medium of the present application stores an existing bridge pile foundation detection program based on the phase difference method, wherein when the existing bridge pile foundation detection program based on the phase difference method is executed by a processor, the steps of the existing bridge pile foundation detection method based on the phase difference method as described above are implemented.

[0101] Among them, the method implemented when the existing bridge pile foundation detection program based on the phase difference method is executed can refer to the various embodiments of the existing bridge pile foundation detection method based on the phase difference method of the present application, and will not be repeated here.

[0102] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0103] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0104] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0105] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0106] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0107] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0108] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting existing bridge pile foundations based on a phase difference method, characterized in that: The following steps are involved: Acquire a first signal and a second signal detected by acceleration sensors arranged at two vertical intervals after striking the pile foundation; Find significant extrema in the first and second signals, including: Normalizing the first signal and the second signal to obtain a first normalized signal and a second normalized signal; An extreme value detection algorithm is used to extract effective extreme values ​​in the first normalized signal and the second normalized signal, including: extracting preliminary extreme values ​​in the first normalized signal and the second normalized signal by adjusting a prominence threshold of the extreme value detection algorithm; matching the preliminary extreme value in the first normalized signal with the preliminary extreme value in the second normalized signal with the closest time difference as the effective extreme value, and deleting the remaining preliminary extreme values; Obtaining a periodic phase difference between a valid extreme value in the first signal and a nearest valid extreme value in the second signal; According to the abnormal changes in the periodic phase difference, the echo time is determined to determine the defect location or pile length.

2. The existing bridge pile foundation detection method based on the phase difference method as claimed in claim 1 is characterized in that: The step of extracting preliminary extreme values ​​from the first normalized signal and the second normalized signal by adjusting the prominence threshold of the extreme value detection algorithm includes: Setting an initial prominence threshold of an extremum detection algorithm to extract extrema in the first normalized signal and the second normalized signal; comparing the difference in the number of extreme values ​​in the first normalized signal and the second normalized signal; When the quantitative difference is greater than the set difference threshold, the prominence threshold of the extreme value detection algorithm is adjusted, and the extreme values ​​in the first normalized signal and the second normalized signal are extracted again until the quantitative difference between the extreme values ​​in the first normalized signal and the second normalized signal is less than the set difference threshold, thereby obtaining the preliminary extreme values ​​in the first normalized signal and the second normalized signal.

3. The existing bridge pile foundation detection method based on the phase difference method as claimed in claim 1, characterized in that: The step of matching the preliminary extreme value in the first normalized signal with the preliminary extreme value with the closest time difference in the second normalized signal as the effective extreme value, and deleting the remaining preliminary extreme values, comprises: Matching each preliminary extreme value in the first normalized signal with a preliminary extreme value in the second normalized signal with the closest time difference in chronological order, and removing or marking the preliminary extreme value set in the second normalized signal; Until all the preliminary extreme values ​​in the first normalized signal reach the preliminary extreme values ​​in the second normalized signal, or all the preliminary extreme values ​​in the second normalized signal are removed or marked; The preliminary extreme value in the first normalized signal and the preliminary extreme value matched in the second normalized signal are taken as the effective extreme value.

4. The existing bridge pile foundation detection method based on the phase difference method as claimed in claim 3 is characterized in that: The step of obtaining the periodic phase difference between the effective extreme value in the first signal and the nearest effective extreme value in the second signal includes: subtracting the effective extreme value moment in each second normalized signal from the corresponding effective extreme value moment in the matching first normalized signal to obtain the periodic phase difference.

5. The existing bridge pile foundation detection method based on the phase difference method as claimed in claim 4, characterized in that: The time when the periodic phase difference is a negative value corresponds to the echo time.

6. The existing bridge pile foundation detection method based on phase difference method as claimed in claim 1, characterized in that: When the time corresponding to the first preliminary extreme value in the first normalized signal is later than the time corresponding to the first preliminary extreme value in the second normalized signal, the first preliminary extreme value in the first normalized signal is eliminated.

7. The existing bridge pile foundation detection method based on phase difference method as claimed in claim 1, characterized in that: The extreme values ​​are peaks or troughs.

8. An existing bridge pile foundation detection device based on phase difference method, characterized in that: include: A signal acquisition module, which is used to acquire a first signal and a second signal detected by two acceleration sensors arranged at vertical intervals after the pile foundation is struck; An extreme value extraction module, which is used to find the effective extreme values ​​in the first signal and the second signal, includes: Normalizing the first signal and the second signal to obtain a first normalized signal and a second normalized signal; An extreme value detection algorithm is used to extract effective extreme values ​​in the first normalized signal and the second normalized signal, including: extracting preliminary extreme values ​​in the first normalized signal and the second normalized signal by adjusting a prominence threshold of the extreme value detection algorithm; matching the preliminary extreme value in the first normalized signal with the preliminary extreme value in the second normalized signal with the closest time difference as the effective extreme value, and deleting the remaining preliminary extreme values; A phase difference calculation module, which is used to obtain a periodic phase difference between a valid extreme value in the first signal and a nearest valid extreme value in the second signal; The echo determination module is used to determine the echo time according to the abnormal change of the periodic phase difference, so as to determine the defect position or pile length.

Images