Pile foundation damage identification method and device and storage medium

Abstract

The invention discloses a pile foundation damage identification method and device and a storage medium, and belongs to the technical field of engineering detection.The method comprises the following steps that structural dynamic response signals under wave excitation in the intact state and the current state of an ocean structural pile are obtained; the penalty factor of each frequency component in variational mode decomposition is adaptively adjusted through the penalty weight coefficient to decompose the dynamic response signal, and a decomposition result corresponding to each mode number is obtained; performing evaluation based on the signal integrity, and determining an impact signal in a decomposition result corresponding to the modal number of the maximum signal integrity as a damage characteristic sub-signal; calculating an energy factor of an effective component of the dynamic response signal according to the damage characteristic sub-signal; and judging whether a certain point of the structure is damaged or not according to the difference between the energy factors. According to the method, the penalty factor of each frequency component is adaptively adjusted through the penalty weight coefficient, and the optimal modal number is determined through the signal integrity of the decomposition result, so that the effective signal is extracted, and the purpose of accurately identifying the local damage of the pile foundation is achieved.

Description

Technical Field

[0001] The invention relates to a pile foundation damage identification method, device and storage medium, belonging to the technical field of engineering detection. Background Art

[0002] The damage research method based on dynamic fingerprints uses interdisciplinary technologies such as structural vibration theory, vibration testing technology and data processing technology, and is considered to be the most promising structural non-destructive testing method. At the same time, waves are a common environmental excitation for offshore buildings, and the use of dynamic response under wave excitation to identify offshore structural damage has broad application prospects.

[0003] The dynamic response of pile foundation under wave excitation has the phenomenon of multi-type signal mixing, so signal reconstruction is crucial for damage detection of pier pile foundation. The variational mode decomposition (VMD) method can effectively avoid the modal aliasing problem in signal reconstruction, but due to the complex spectrum of dynamic response under wave excitation, the number of modes and penalty factors required for decomposition will seriously affect the decomposition result, resulting in low accuracy of local damage identification of pile foundation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a pile foundation damage identification method, which adaptively adjusts the penalty factor of each frequency component through the penalty weight coefficient, and determines the optimal modal number through the signal integrity of the decomposition result, thereby refining the effective signal and achieving the purpose of accurately identifying local damage of the pile foundation.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a pile foundation damage identification method, comprising the following steps:

[0007] Obtain the structural dynamic response signals of the marine structure piles under wave excitation in the intact state and the current state;

[0008] The penalty factor of each frequency component in the variational modal decomposition is adaptively adjusted by the penalty weight coefficient to decompose the dynamic response signal and obtain the decomposition result corresponding to each modal number;

[0009] The decomposition results are evaluated based on the signal integrity, and the modal number corresponding to the maximum signal integrity is determined as the modal number required for decomposition. The impact signal in the decomposition result corresponding to this modal number is used as the damage characteristic sub-signal:

[0010] Calculate the energy factor of the effective component of the dynamic response signal in the intact state and the current state according to the damage characteristic sub-signal;

[0011] The difference between the energy factors in the intact state and the current state is used to determine whether there is damage at a certain point in the structure.

[0012] The dynamic response signal is the acceleration of multiple units of the marine structure pile foundation.

[0013] The unconstrained variational model of variational mode decomposition is as follows:

[0014] (1)

[0015] in is the penalty factor, K is the mode number, is the Dirac distribution, i is the imaginary unit, is the convolution operation, is the kth IMF signal, is the center frequency of the kth IMF signal, is the original signal, is the Lagrange multiplier, is the variational mode evaluation function.

[0016] The high-frequency analytical signal equation used to adaptively adjust the penalty factor of each frequency component in the variational mode decomposition through the penalty weight coefficient is:

[0017] (2)

[0018] in, is the frequency, is the penalty factor, is the penalty coefficient, , is the Hilbert transform of the kth mode after n+1 update iterations, is the Hilbert transform of the original signal, is the Lagrange multiplier after n update iterations. is the Hilbert transform of the ith mode after n update iterations, is the center frequency of the kth IMF signal after n update iterations, is the Lagrange multiplier.

[0019] Penalty coefficient The calculation method is:

[0020] (3)

[0021] in, is a parameter, , reflecting the smoothness of each mode, and are the minimum and maximum values ​​of the smoothness of each mode respectively.

[0022] The signal integrity F is calculated as follows:

[0023] (4)

[0024] in, is the kurtosis and A is the amplitude.

[0025] The specific calculation method of energy factor E is:

[0026] (5)

[0027] in, yes The Hilbert transform of the local bending component of is the local bending component and t is the time.

[0028] The energy factor difference between the intact state and the current state is used to determine whether there is damage at a certain point in the structure. Specifically, the energy damage index is constructed. :

[0029] (6)

[0030] in, and Represent the energy in healthy and damaged conditions respectively.

[0031] In a second aspect, the present invention provides a pile foundation damage identification device, comprising a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method.

[0032] In a third aspect, the present invention provides a computer-readable storage medium having a computer program / instruction stored thereon, which, when executed by a processor, implements the steps of the pile foundation damage identification method.

[0033] The beneficial effects of the present invention are as follows: the present invention provides a pile foundation damage identification method, which decomposes the dynamic response signal by adaptively adjusting the penalty factor of each frequency component in the variational modal decomposition through the penalty weight coefficient, and can decompose the mixed signal with a large frequency range span to ensure the integrity of the high-frequency signal. In addition, the decomposition result is evaluated based on the signal integrity, and the modal number corresponding to the maximum signal integrity is determined as the modal number required for decomposition, and the impact signal in the impact signal decomposition result corresponding to this modal number is used as the damage characteristic sub-signal, which can retain the dynamic characteristics of the impact signal to the maximum extent. In summary, through the setting of the above-mentioned signal integrity and penalty weight coefficient, the problem of effective modal extraction and damage identification of complex dynamic response signals under wave excitation can be solved, and method support is provided for damage detection and health assessment of offshore structures under wave excitation; it can be applied to civil engineering projects such as cross-sea bridges, offshore platforms, and wind turbine foundations, and has a wide range of applications; it can be implemented in combination with programming to realize damage identification visualization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a bird's-eye view of the high-pile wharf experimental model in an embodiment of the present invention;

[0035] Figure 2 It is a cross-sectional view of a high-pile wharf experimental model in an embodiment of the present invention;

[0036] Figure 3 It is a sensor arrangement diagram in an embodiment of the present invention;

[0037] Figure 4 This is a diagram of damage forms in an embodiment of the present invention;

[0038] Figure 5 This is a scene diagram of a wave excitation test in an embodiment of the present invention;

[0039] Figure 6 This is a power response signal acquisition diagram in an embodiment of the present invention;

[0040] Figure 7 is the acceleration response of each node under the 10% damage condition in the embodiment of the present invention;

[0041] Figure 8 Extraction of effective component of node 7 under 10% damage condition in the embodiment of the present invention (a) Original acquisition acceleration signal of node 7 under 10% damage condition; (b) Extraction of effective component of node 7 under 10% damage condition;

[0042] Fig. 9 It is an identification curve diagram under different damage conditions in the embodiment of the present invention;

[0043] Fig.10 The figure is a schematic diagram of a method flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0045] Example 1

[0046] like Fig.10 As shown, this embodiment discloses a pile foundation damage identification method, comprising the following steps:

[0047] Step 1: Obtain the structural dynamic response signals of the marine structure piles under wave excitation in the intact state and the current state.

[0048] Step 2: The penalty factor of each frequency component in the variational modal decomposition is adaptively adjusted by the penalty weight coefficient to decompose the dynamic response signal and obtain the decomposition result corresponding to each mode number.

[0049] Step three, evaluate the decomposition results based on signal integrity, determine the mode number corresponding to the maximum signal integrity as the mode number required for decomposition, and use the impact signal in the decomposition result corresponding to this mode number as the damage characteristic sub-signal.

[0050] Step 4: Calculate the energy factor of the effective component of the dynamic response signal in the intact state and the current state according to the damage characteristic sub-signal.

[0051] Step 5: Use the difference between the energy factors in the intact state and the current state to determine whether there is damage at a certain point in the structure.

[0052] The present invention proposes to decompose the dynamic response signal by adaptively adjusting the penalty factor of each frequency component in the variational modal decomposition through the penalty weight coefficient, which can decompose the mixed signal with a large frequency range span to ensure the integrity of the high-frequency signal. In addition, the impact signal decomposition result is evaluated based on the signal integrity, and the mode number corresponding to the maximum signal integrity is determined as the mode number required for decomposition, and the impact signal decomposition result corresponding to this mode number is used as the damage characteristic sub-signal, which can retain the dynamic characteristics of the impact signal to the maximum extent. In summary, through the setting of the above-mentioned signal integrity and penalty weight coefficient, the problem of effective mode extraction and damage identification of complex dynamic response signals under current wave excitation can be solved.

[0053] Example 2

[0054] The present invention discloses a pile foundation damage identification method, comprising the following steps:

[0055] Step 1: Obtain the structural dynamic response signal of the marine structure pile under wave excitation in the intact state and the current state. Specifically, the dynamic response signal is the acceleration of multiple units of the marine structure pile foundation.

[0056] Step 2: The penalty factor of each frequency component in the variational modal decomposition is adaptively adjusted by the penalty weight coefficient to decompose the dynamic response signal and obtain the decomposition result corresponding to each mode number.

[0057] The original variational mode decomposition method (hereinafter referred to as VMD) is an optimization method based on spectrum and energy characteristics. The idea of ​​this method is to obtain the analytical signal of the original signal through Hilbert transform, decompose it into a specified number of intrinsic mode function signals (IMF), and use the Gaussian smoothness of the analytical signal of each IMF component to estimate the bandwidth. By adjusting the center frequency of each IMF component, the sum of the estimated bandwidth, that is, the square norm of the gradient is minimized. To solve this optimization problem, it is necessary to introduce penalty factors and Lagrange multipliers. The unconstrained variational model after transformation is as follows:

[0058] (1)

[0059] in is the penalty factor, K is the mode number, is the Dirac distribution, i is the imaginary unit, is the convolution operation, is the kth IMF signal, is the center frequency of the kth IMF signal, is the original signal, is the Lagrange multiplier, is the variational mode evaluation function;

[0060] Variational mode decomposition can effectively avoid the mode aliasing problem existing in the traditional empirical mode decomposition method (hereinafter referred to as EMD) and its derivative methods. However, VMD still has some limitations. Its system function can be written as:

[0061] (2)

[0062] in It is a The Wiener filter with a center frequency can change the filtering strength of the Wiener filter by adjusting the penalty factor α. The larger the α value, the narrower the bandwidth of all modes. However, for mixed signals, there may be both broadband and narrowband signal modes. If all modes have the same α value, it may cause unreasonable decomposition of signal components.

[0063] During the update process, for low frequency signals, Smaller, in A larger α value is required to allow low-frequency signals to pass through, and a smaller α value is required to allow high-frequency signals to pass through. Considering that the optimization goal of VMD is to minimize the sum of the Gaussian smoothness of each component analytical signal, and the Gaussian smoothness of the high-frequency analytical signal is larger, in order to ensure the integrity of the high-frequency signal, the Gaussian smoothness of the high-frequency analytical signal can be weighted during the optimization process. According to the alternating direction multiplier method, the final update formula for obtaining the high-frequency analytical signal is:

[0064] (3)

[0065] Among them, among them, is the frequency, is the penalty factor, is the penalty coefficient, , is the Hilbert transform of the kth mode after n+1 update iterations, is the Hilbert transform of the original signal, is the Lagrange multiplier after n update iterations. is the Hilbert transform of the ith mode after n update iterations, is the center frequency of the kth IMF signal after n update iterations, The present invention proposes a penalty weight coefficient to adjust the smoothness of the high-frequency analytical signal, thereby realizing adaptive adjustment of the penalty factor of the high-frequency component. To improve :

[0066] (4)

[0067] in, is a parameter, , reflecting the smoothness of each mode, and are the minimum and maximum values ​​of the smoothness of each mode respectively.

[0068] The IAVMD method updates the penalty weight coefficient according to the smoothness of each mode at each iteration. , Reuse penalty coefficient Adaptive adjustment of penalty factor , thereby completely decomposing the impact signal.

[0069] Step three, evaluate the decomposition results based on signal integrity, determine the mode number corresponding to the maximum signal integrity as the mode number required for decomposition, and use the impact signal in the decomposition result corresponding to this mode number as the damage characteristic sub-signal.

[0070] The present invention introduces the signal integrity index into the variational mode, establishes a signal decomposition method that integrates signal integrity and variational mode (hereinafter referred to as IAVMD), decomposes mixed signals with a large frequency range, and proposes a signal statistical information evaluation index: signal integrity F:

[0071] (5)

[0072] in, is the kurtosis, and A is the amplitude. The IAVMD method pre-sets the range of the modal number K, evaluates the decomposition results under each modal number based on the signal integrity within the range, and selects the modal number corresponding to the maximum signal integrity as the modal number required for decomposition. The impact signal in the decomposition result corresponding to this modal number is the damage characteristic sub-signal, which can retain its dynamic characteristics to the maximum extent.

[0073] Step 4: Calculate the energy factor of the effective component of the dynamic response signal in the intact state and the current state according to the damage characteristic sub-signal.

[0074] When the structural stiffness of an object changes or is subjected to external excitation, the energy of its vibration signal will change. Therefore, the local bending component with the strongest energy is selected to construct an energy damage index to achieve damage identification. To construct an energy damage index, it is necessary to obtain the instantaneous energy E of the damage characteristic target sub-signal:

[0075] (6)

[0076] in, yes The Hilbert transform of the local bending component of is the local bending component and t is the time.

[0077] Step 5: Use the difference between the energy factors of the intact state and the current state to determine whether there is damage at a certain point in the structure. Use the signal energy E to construct the energy damage index :

[0078] (7)

[0079] in, and Represent the energy in healthy and damaged conditions respectively.

[0080] Example 3

[0081] The method of Example 2 is specifically applied to the identification of pile foundation damage of a high-pile wharf. First, a high-pile wharf model is made in the laboratory and placed in a wind and wave flume. Figure 1 , Figure 2, an acceleration sensor is arranged every 0.01m from top to bottom on the second pile on the left side of the front row, a total of 13 acceleration sensors are arranged, numbered 1, 2, ..., 13 from top to bottom, the sensor arrangement diagram is shown in Figure 3 , the sensor picks up vibration in the direction perpendicular to the front of the dock. Figure 4 The damage length is set to 0.01m, the damage width and the test conditions are as follows: 5% damage is set to 4mm damage width; 20% damage is set to 17mm damage width; 30% damage is set to 24mm damage width. Regular wave excitation is used, with a wave period of 1, a water depth of 1m, and a wave height of 0.1m, to collect the acceleration response before and after the pile body is damaged. Figure 5 This is a scene diagram of the wave excitation test in the embodiment of the present invention. Figure 6 This is a diagram of the dynamic response signal acquisition in an embodiment of the present invention.

[0082] The identification method specifically includes the following steps:

[0083] Step 1: Obtain the acceleration response of the structure in the current state and intact state.

[0084] Use DH5920 vibration pickup to obtain its acceleration response signal, such as Figure 7 shown.

[0085] Step 2: The penalty factor of each frequency component in the variational modal decomposition is adaptively adjusted through the penalty weight coefficient, and the optimal mode number is determined by the signal integrity of the decomposition result; the wave period is 1s. The decomposition diagram is as follows: Figure 8 shown.

[0086] Step 3: Calculate the energy factor of the effective component of the dynamic response signal in the intact state and the current state. Under different damage conditions, like Fig. 9 shown.

[0087] After effective signal extraction, the HMDI index shows an obvious "peak" at node 6. This damage index can well identify local damage of the structure under regular wave excitation.

[0088] The present invention combines the analytical solution of dynamic response under wave excitation and the empirical mode decomposition method to realize the extraction of effective components of dynamic signals under wave excitation. The constructed indicators have good sensitivity and can detect high-pile pier damage in a timely, early and low-cost manner, proving that the method has good applicability.

[0089] Example 4

[0090] This embodiment discloses a pile foundation damage identification device, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method described in Example 1 or 2.

[0091] Example 5

[0092] This embodiment introduces a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method described in Embodiment 1 or 2 are executed.

[0093] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0097] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pile foundation damage identification method, characterized in that: The following steps are involved: Obtain the dynamic response signals of the structure under wave excitation in the intact state and current state of the marine structure pile; The penalty factor of each frequency component in the variational modal decomposition is adaptively adjusted by the penalty weight coefficient to decompose the dynamic response signal and obtain the decomposition result corresponding to each modal number; The decomposition results are evaluated based on the signal integrity, the mode number corresponding to the maximum signal integrity is determined as the mode number required for decomposition, and the impact signal in the decomposition result corresponding to the mode number required for decomposition is used as the damage characteristic sub-signal; Calculate the energy factor of the effective component of the dynamic response signal in the intact state and the current state according to the damage characteristic sub-signal; The difference between the energy factors in the intact state and the current state is used to determine whether there is damage at a certain point in the structure.

2. The pile foundation damage identification method according to claim 1, characterized in that: The dynamic response signal is the acceleration of multiple units of the marine structure pile foundation.

3. The pile foundation damage identification method according to claim 1, characterized in that: The unconstrained variational model of variational mode decomposition is as follows: （1） in is the penalty factor, is the modal number, is the Dirac distribution, i is the imaginary unit, is the convolution operation, is the kth IMF signal, is the center frequency of the kth IMF signal, is the original signal, is the Lagrange multiplier, is the variational mode evaluation function.

4. The pile foundation damage identification method according to claim 3, characterized in that: The high-frequency analytical signal equation used to adaptively adjust the penalty factor of each frequency component in the variational mode decomposition through the penalty weight coefficient is: （2） in, is the frequency, is the penalty factor, is the penalty coefficient, , is the Hilbert transform of the kth mode after n+1 update iterations, is the Hilbert transform of the original signal, is the Lagrange multiplier after n update iterations, is the Hilbert transform of the ith mode after n update iterations, is the center frequency of the kth IMF signal after n update iterations, is the Lagrange multiplier.

5. The pile foundation damage identification method according to claim 4, characterized in that: Penalty coefficient The calculation method is: （3） in, is a parameter, , reflecting the smoothness of each mode, and are the minimum and maximum values ​​of the smoothness of each mode respectively.

6. The pile foundation damage identification method according to claim 5, characterized in that: The signal integrity F is calculated as follows: （4） in, is the kurtosis and A is the amplitude.

7. The pile foundation damage identification method according to claim 6, characterized in that: The specific calculation method of energy factor E is: （5） in, yes The Hilbert transform of the local bending component of is the local bending component and t is the time.

8. The pile foundation damage identification method according to claim 7, characterized in that: The energy factor difference between the intact state and the current state is used to determine whether a certain point of the structure is damaged. Specifically, the energy damage index is constructed. : （6） in, and Represent the energy in healthy and damaged conditions respectively.

9. A pile foundation damage identification device, characterized in that: It comprises a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 8.

10. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instruction is executed by a processor, the steps of the pile foundation damage identification method described in any one of claims 1-8 are implemented.

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