Method and system for detecting bearing capacity of concrete precast pile

Abstract

The invention belongs to the technical field of data processing, and particularly relates to a concrete precast pile bearing capacity detection method and system, and the method comprises the steps: obtaining a speed signal and a force signal; decomposing the speed signal into an IMF component and a residual signal through empirical mode decomposition; calculating an instantaneous energy spectrum according to the high-frequency IMF component, and obtaining impact energy, defect energy and defect occurrence time; obtaining a bearing capacity index according to the lateral resistance diagnosis set, the maximum value of the force signal and the displacement variation; according to the defect energy, the impact energy, the defect occurrence moment and the time when the stress wave reaches the pile bottom, a pile body integrity factor is obtained; and carrying out bearing capacity detection according to the pile body integrity factor and the bearing capacity index. According to the method, decoupling of the pile body defect, the side friction resistance and the pile end resistance response is achieved through empirical mode decomposition, comprehensive evaluation is conducted through the pile body integrity factor and the bearing capacity index, and the accuracy and reliability of precast pile bearing capacity detection are improved.

Description

Technical Field

[0001] This invention relates to the field of data processing technology. More specifically, this invention relates to a method and system for testing the bearing capacity of precast concrete piles. Background Technology

[0002] Precast piles are piles manufactured in a standardized factory and then transported to the site for pile driving. Their core function is to transfer the load of the superstructure to the deep bearing soil layer. Their bearing capacity and the integrity of the pile structure are key factors in ensuring the safety and stability of the superstructure. Precast piles are widely used in engineering projects due to their controllable quality and convenient construction. However, during the transportation, hoisting, and intense impact of pile driving, the pile body may suffer structural damage such as cracks and fractures. Furthermore, the final actual bearing capacity of the pile foundation is highly dependent on the actual interaction between the pile body and the complex and uneven geological conditions of the site, and the result of this interaction is uncertain after construction. Therefore, verifying whether the pile foundation has achieved the ideal bearing capacity requirements is crucial.

[0003] In related technologies, for example, Chinese patent application CN115897686A discloses a method for detecting and evaluating the bearing capacity of precast pipe piles, including: acquiring preset pile side friction data and preset compressive bearing capacity data of the precast pipe pile; obtaining theoretical pile end resistance data based on the preset pile side friction data and preset compressive bearing capacity data; acquiring total load data and measured pile end resistance data during the pile driving process of the precast pipe pile, wherein the measured pile end resistance data is collected through a gasket sensor; if the total load data is greater than or equal to the preset compressive bearing capacity data and the measured pile end resistance data is greater than or equal to the theoretical pile end resistance data, the precast pipe pile driving construction is stopped; and obtaining the vertical compressive bearing capacity of the pipe pile in the long-term use stage after pile driving based on the total load data and measured pile end resistance data.

[0004] However, in related technologies, the signal collected at the top of the pile is a complex non-stationary signal. Multiple physical responses, such as reflected waves caused by pile defects, forced vibrations caused by pile-soil friction, and pile displacement caused by pile end resistance, are superimposed. This complex signal characteristic makes it difficult for existing technologies to accurately distinguish the contributions of pile side friction and pile end resistance to the total bearing capacity, thus making it impossible to reliably assess the true vertical compressive bearing capacity of precast piles. Summary of the Invention

[0005] To address the technical problem that existing technologies struggle to effectively decouple complex aliased signals collected from the pile top, making it impossible to accurately distinguish between pile side friction and pile end resistance, thus leading to inaccurate precast pile bearing capacity test results, this invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides a method for detecting the bearing capacity of precast concrete piles, comprising: acquiring velocity and force signals based on acceleration and strain signals at the top of the precast pile; decomposing the velocity signals into multiple IMF components and residual signals using an empirical mode decomposition algorithm; calculating an instantaneous energy spectrum based on a defect diagnosis set composed of high-frequency IMF components; taking the moment corresponding to the largest peak in the instantaneous energy spectrum as the impact moment, the largest peak as the impact energy, and taking the peak values ​​after the impact moment that are greater than a preset energy threshold and whose duration is less than a preset time threshold as candidate peak values, taking the peak value with the largest energy among the candidate peak values ​​as the secondary energy peak, the value of the secondary energy peak as the defect energy, and the defect energy corresponding to... The moment of impact is the moment the defect occurs; the IMF components outside the defect diagnosis set are combined into a side resistance diagnosis set; the energy sequence of each IMF component in the side resistance diagnosis set is obtained, and the total energy of each energy sequence after the impact moment is calculated; the maximum value in the force signal is obtained; the displacement change is determined based on the difference in stable displacement before and after the impact of the residual signal; the bearing capacity index is obtained based on the total energy of the side resistance diagnosis set, the impact energy, the maximum value of the force signal, and the total displacement change; the time when the stress wave reaches the bottom of the pile is calculated; the pile integrity factor is obtained based on the defect energy, the impact energy, the moment of defect occurrence, and the time when the stress wave reaches the bottom of the pile; the bearing capacity of the precast pile is tested based on the pile integrity factor and the bearing capacity index.

[0007] This invention decomposes the physically complex aliased signal into a high-frequency IMF component reflecting defects, a mid-to-low-frequency IMF component reflecting side resistance, and a residual signal reflecting pile end displacement by performing empirical mode decomposition on the velocity signal. This effectively decouples the three key physical responses of pile defects, side friction, and pile end resistance. By constructing an instantaneous energy spectrum from the high-frequency components, the energy and location of pile defects are extracted. By calculating the total energy from the side resistance diagnostic set and combining it with impact energy, and by obtaining the displacement change from the residual signal and combining it with the maximum force signal, side resistance and end resistance terms are constructed, respectively, thus obtaining the bearing capacity index. This invention comprehensively evaluates the bearing capacity of precast piles through two dimensions: the pile integrity factor and the bearing capacity index. This overcomes the problem of inaccurate evaluation caused by signal aliasing in related technologies, improving the accuracy and reliability of precast pile bearing capacity testing.

[0008] Preferably, the step of obtaining velocity and force signals based on acceleration and strain signals at the top of the precast pile includes: acquiring acceleration and strain signals and obtaining the section modulus of the precast pile; integrating the acceleration signal to obtain the velocity signal; and obtaining the force signal based on the strain signal and the section modulus of the pile.

[0009] Preferably, the step of calculating the instantaneous energy spectrum based on the defect diagnosis set composed of high-frequency IMF components includes: selecting high-frequency IMF components to form a defect diagnosis set, applying Hilbert transform to each IMF component in the defect diagnosis set to obtain the corresponding analytical signal, calculating the square of the instantaneous amplitude of each analytical signal to form an energy sequence, and adding the energy sequences in pairs to obtain the instantaneous energy spectrum.

[0010] This invention obtains analytical signals by applying Hilbert transform to high-frequency IMF components, constructs an energy sequence by calculating the square of the instantaneous amplitude, and finally adds the phases to obtain the instantaneous energy spectrum. This method converts high-frequency vibration signals into an energy spectrum that can instantly reflect energy changes. This method provides the necessary prerequisite for accurately identifying the peak impact energy and the transient secondary energy peak caused by pile defects in subsequent steps.

[0011] Preferably, the high-frequency IMF components are the three IMF components that are first decomposed from the velocity signal.

[0012] Preferably, the bearing capacity index satisfies the following relationship: In the formula, For bearing capacity index, For the moment of impact, The signal ends at the time. For the diagnosis of lateral resistance, the first The IMF component in the first The value at each moment, Representative of the side resistance diagnosis set The integral of the energy sequence of each IMF component after the impact time. To impact energy, The maximum value in the force signal. The change in displacement The number of IMF components in the side resistance diagnosis. To prevent division by zero, and These are the weights of the side resistance term and the end resistance term, respectively.

[0013] This invention constructs a bearing capacity index by using the ratio of the total energy of the side resistance diagnostic set to the impact energy as the side resistance term and the ratio of the maximum force signal to the displacement change as the end resistance term, and by weighted summation. This index measures the energy consumed by the pile body to overcome soil friction and the stiffness of the pile end to resist penetration, thus realizing the separate evaluation and combination of the two main sources of total bearing capacity.

[0014] Preferably, determining the displacement change based on the difference in stable displacement of the residual signal before and after the impact includes: taking the difference between the value of the stable change at the time after the impact in the residual signal and the value of the stable change at the time before the impact in the residual signal as the displacement change.

[0015] Preferably, the stable change time is the end time after the residual signal has completely decayed after the impact, and the start time before the impact.

[0016] Preferably, the pile integrity factor satisfies the following relationship: In the formula, For pile integrity factor, For defect energy, To impact energy, The time when the defect occurred. The time it takes for the stress wave to reach the bottom of the pile. It is an exponential function with the natural constant as its base. These are calibration coefficients.

[0017] This invention constructs a pile integrity factor, which combines the ratio of defect energy to impact energy (reflecting the severity of defects) with the ratio of defect occurrence time to stress wave arrival time at the pile bottom (reflecting the location of defects). This not only considers the magnitude of defect reflection energy but also corrects for the energy loss of stress waves during propagation, thus achieving a comprehensive assessment of the structural integrity of the pile.

[0018] Preferably, the precast pile bearing capacity test based on the pile integrity factor and bearing capacity index includes: if the pile integrity factor of the precast pile to be tested is greater than the integrity threshold and the bearing capacity index is greater than the bearing capacity index threshold, then the bearing capacity of the precast pile to be tested is normal.

[0019] This invention sets dual thresholds for the pile integrity factor and the bearing capacity index, requiring the precast pile under test to meet both conditions of structural integrity and bearing capacity compliance before it is judged as normal. This avoids misjudgment caused by relying on a single indicator, making the bearing capacity test results more rigorous, comprehensive and reliable.

[0020] Secondly, the present invention provides a concrete precast pile bearing capacity testing system, including a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the above-mentioned concrete precast pile bearing capacity testing method is implemented.

[0021] By adopting the above technical solution, a computer program for testing the bearing capacity of precast concrete piles is generated and stored in a memory so that it can be loaded and executed by a processor. This allows for the creation of a terminal device based on the memory and processor, making it convenient to use.

[0022] The beneficial effects of this invention are as follows: This invention adaptively decomposes non-stationary velocity signals using an empirical mode decomposition algorithm, decomposing them into multiple intrinsic mode function components and residual signals corresponding to the physical causes of pile defects, pile-soil side friction, and pile end resistance, respectively, thus effectively separating the previously highly aliased response signals. Furthermore, this invention constructs an instantaneous energy spectrum from the high-frequency components characterizing defects, and combines this with defect energy, impact energy, defect occurrence time, and stress wave propagation time to construct a pile integrity factor including location correction, achieving a comprehensive assessment of the severity and location of pile structural defects. Simultaneously, this invention characterizes the energy consumed by the pile to overcome side friction using the total post-impact energy of the side resistance diagnostic set, and obtains the pile end plastic settlement (displacement change) using the residual signal, combining this with the maximum impact force to characterize the pile end stiffness against penetration, and then combining these to obtain the bearing capacity index, achieving independent assessment and combination of the two sources of total bearing capacity: side friction and pile end resistance. Ultimately, this invention overcomes the problem in related technologies where signal aliasing prevents accurate separation of defects, side resistance, and end resistance responses, leading to biased or inaccurate evaluation results. By combining the dual indicators of pile integrity factor and bearing capacity index for joint discrimination, this invention achieves comprehensive and reliable detection of the bearing capacity of precast piles. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a method for testing the bearing capacity of precast concrete piles according to the present invention; Figure 2 This is a schematic illustration of the results of empirical mode decomposition in this invention; Figure 3 This is a schematic illustration of the instantaneous energy spectrum in this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] This invention discloses a method for testing the bearing capacity of precast concrete piles, referring to... Figure 1 This includes steps S1-S5: S1. Deployment and signal acquisition of multi-source sensors, and decomposition of signals.

[0027] It should be noted that the acquired velocity signal is a highly complex non-stationary signal, in which signals from different physical causes (such as transient impact, defect reflection, and soil damping) are superimposed, making direct analysis of the velocity signal impossible. Therefore, the velocity signal needs to be decomposed to separate its different signal components.

[0028] Specifically, high-sensitivity accelerometers and strain sensors are symmetrically installed on the top of the precast piles. A high-strain dynamic testing instrument is activated, and a hammer is released to impact the pile top. Acceleration and strain signals during the impact process are simultaneously acquired and recorded at a sampling frequency of no less than 40kHz. The acquired acceleration signals are integrated to obtain the velocity signal; and the force signal is calculated by combining the acquired strain signal with the pile section modulus.

[0029] Furthermore, the empirical mode decomposition algorithm is applied to decompose the acquired velocity signal to obtain several intrinsic mode function components (IMF components) and residual signals.

[0030] For example, Figure 2 This is the result of empirical mode decomposition.

[0031] S2. Construct the instantaneous energy spectrum based on the IMF components.

[0032] It should be noted that the reflected waves generated by minor defects in the pile body are typical high-frequency, transient signals. After adaptive mode decomposition, the signal will mainly concentrate in the highest frequency IMF components. Defects in precast piles will manifest as abnormal sudden increases in the instantaneous energy of the signal. In order to accurately locate the defect characteristics of precast piles, it is necessary to calculate the instantaneous energy of these high-frequency components. Therefore, this invention constructs an instantaneous energy spectrum based on the IMF components.

[0033] Specifically, firstly, high-frequency IMF components are selected to form a defect diagnosis set. Hilbert transform is applied to each IMF component in the defect diagnosis set to obtain the analytic signal corresponding to each IMF component. The sequence formed by the square of the instantaneous amplitude of each value in the analytic signal corresponding to each IMF component is the energy sequence of each IMF component. The energy sequences of each IMF component are added in pairs to obtain the instantaneous energy spectrum.

[0034] In one embodiment, the high-frequency IMF components are the three IMF components that are first decomposed when the velocity signal is decomposed.

[0035] For example, the energy sequence of the IMF component in the defect diagnosis set is: , and The instantaneous energy spectrum is .

[0036] It should be further explained that the defects of precast piles physically manifest as an abnormal surge in instantaneous energy. However, the original IMF component is a real signal, and its instantaneous amplitude cannot be directly calculated. Therefore, the IMF component is processed by Hilbert transform to convert the real signal into its corresponding analytic signal, and then the instantaneous amplitude characterizing the instantaneous change in energy is extracted from the real signal of the IMF component.

[0037] Furthermore, the moment corresponding to the largest peak in the instantaneous energy spectrum is the impact moment, and the peak that meets the threshold condition after the impact moment is the candidate peak. The peak with the largest energy among the candidate peaks is the secondary energy peak, and the moment corresponding to the secondary energy peak is the defect occurrence moment. The value of the secondary energy peak is the defect energy, and the energy value corresponding to the impact moment is the impact energy. Among them, the peak value that is greater than the preset energy threshold and the peak duration is less than the time threshold satisfies the threshold condition.

[0038] For example, the energy threshold is 0.05 times the impact energy, and the time threshold is 0.5 milliseconds.

[0039] For example, Figure 3 This is the instantaneous energy spectrum in this invention. The largest peak in the figure corresponds to the moment of impact, and the second largest energy peak corresponds to the moment when the impact force of the hammer reaches the defect of the precast pile.

[0040] S3. Obtain the bearing capacity index based on the instantaneous energy spectrum.

[0041] It should be noted that in order to accurately assess the true bearing capacity of the pile foundation, it is necessary to eliminate interference signals that are unrelated to the bearing capacity. Among them, the IMF component outside the defect diagnosis set mainly reflects the forced vibration and damping attenuation characteristics generated by the friction between the pile and the soil, which is related to the side friction resistance. The final residual signal reflects the overall plastic displacement of the pile under hammer impact, which is closely related to the pile end resistance. Therefore, this invention successfully separates the originally mixed signals into independent components corresponding to defects, side resistance, and end resistance, thereby achieving effective decoupling and independent assessment of these two core bearing capacity components.

[0042] Specifically, the IMF components outside the defect diagnosis set are combined into a side resistance diagnosis set. For each IMF component in the side resistance diagnosis set, its energy sequence is obtained. The integral of the energy sequence of each IMF component after the impact time is obtained to obtain the total energy of the corresponding energy sequence of each IMF component after the impact time. The maximum value in the force signal and the difference between the value of the stable change time after the impact time and the value of the stable change time before the impact time in the residual signal are obtained as the displacement change amount. The bearing capacity index is obtained based on the sum of the total energy of each IMF component in the side resistance diagnosis set, the impact energy, and the displacement change amount in the force signal.

[0043] In one embodiment, the two stable changing moments before and after the impact moment are the start moment before the impact occurs and the end moment after the residual signal has completely decayed after the impact occurs.

[0044] Specifically, the bearing capacity index satisfies the following relationship: ; In the formula, For bearing capacity index, For the moment of impact, The signal ends at the time. For the diagnosis of lateral resistance, the first The IMF component in the first The value at each moment, Representative of the side resistance diagnosis set The integral of the energy sequence of each IMF component after the impact time. To impact energy, The maximum value in the force signal. The change in displacement The number of IMF components in the side resistance diagnosis. To prevent division by zero, and These are the side resistance term weights and the end resistance term weights, respectively, in this embodiment. and Both are 0.5. The value is 0.01, and the implementers can determine the values ​​of the three values ​​according to the actual situation.

[0045] in, The lateral resistance term of the bearing capacity of precast piles. This is the integral sum of the energy sequences of all IMF components in the side resistance diagnostic set after the impact moment. It corresponds to the total energy consumed by the pile's vibration energy to overcome soil friction after the impact. The larger this value, the greater the total energy consumed to overcome soil friction, the greater the side resistance overcome by the precast pile, and thus the greater the bearing capacity of the precast pile. Conversely, the smaller this value, the smaller the total energy consumed to overcome soil friction, the smaller the side resistance overcome by the precast pile, and thus the smaller the bearing capacity of the precast pile. The formula uses division by... (The last part is incomplete and requires further context to translate accurately.) The way to The range was adjusted.

[0046] The end resistance term of the precast pile bearing capacity, wherein, This represents the peak load transmitted to the pile during the hammer impact process. This represents the permanent penetration displacement of the pile bottom into the bearing stratum after the pile has been subjected to this peak load. This ratio represents the stiffness of the precast pile tip in resisting deformation and penetrating the ground. The larger the ratio, the smaller the plastic settlement at the pile tip under peak load, the stronger its resistance to penetration, the greater the corresponding end resistance, and the greater the bearing capacity of the precast pile. Conversely, the smaller the ratio, the greater the plastic settlement at the pile tip under peak load, the weaker its resistance to penetration, the smaller the corresponding end resistance, and the smaller the bearing capacity of the precast pile.

[0047] It should be further explained that in geotechnical engineering, the total bearing capacity of a pile foundation is physically derived from the side friction, represented by the friction between the pile side and the soil, and the end resistance, represented by the supporting force of the pile bottom against the bearing stratum. Therefore, the total bearing capacity of a precast pile is the sum of the side friction and the end resistance. Thus, the bearing capacity index is obtained by weighted summation of the side resistance and end resistance terms, which adjusts these two terms with different dimensions to ensure that they can be numerically combined. This allows the final bearing capacity index to comprehensively and effectively characterize the total bearing capacity of the precast pile, thereby enabling subsequent bearing capacity testing.

[0048] S4. Obtain the pile integrity factor based on the instantaneous energy spectrum.

[0049] It should be noted that the integrity of the pile structure is a prerequisite for ensuring the bearing capacity of precast piles. If defects such as cracks, diameter reduction, or fractures exist in the pile body, the actual bearing capacity of the pile will be lower than the design value. Instantaneous energy spectrum analysis identifies the defect energy and the time of defect occurrence caused by the defects. The magnitude of the defect energy reflects the severity of the defect, while the time of defect occurrence corresponds to the location of the defect within the pile body. To assess the impact of these defects on the pile structure, this invention obtains a pile integrity factor based on the defect energy, impact energy, and the time of defect occurrence.

[0050] Specifically, the time it takes for the stress wave to reach the bottom of the pile is obtained, and the pile integrity factor is obtained based on the ratio between the defect energy and the impact energy, as well as the time when the defect occurs and the time when the stress wave reaches the bottom of the pile.

[0051] In one embodiment, the pile integrity factor satisfies the following relationship: ; In the formula, For pile integrity factor, For defect energy, To impact energy, The time when the defect occurred. The time it takes for the stress wave to reach the bottom of the pile. It is an exponential function with the natural constant as its base. As calibration coefficients, in this embodiment The value is 2, and the personnel implementing the program can also adjust it according to the actual working conditions.

[0052] in, This ratio reflects the severity of the defect. The larger the ratio, the higher the proportion of energy reflected by the precast pile defect to the total energy. This corresponds to more severe structural discontinuities or damage. The more likely the precast pile has structural incompleteness, the smaller the pile integrity factor. The smaller the ratio, the lower the proportion of energy reflected by the precast pile defect to the total energy. This corresponds to less severe structural discontinuities or a more complete and continuous pile structure. The more likely the precast pile has an intact pile structure, the larger the pile integrity factor.

[0053] This is the position attenuation correction term. Due to energy loss caused by material damping and side friction during stress wave propagation within the pile, this energy loss is compensated for by the position attenuation correction term. Wherein, This represents the relative depth of defects in the precast pile structure. The smaller the value, the closer the defect occurred to the impact time. Since the impact originated from the top of the pile, the shallower the defect in the precast pile structure and the closer it is to the top of the pile, the shorter the distance the stress wave travels within the pile body and the smaller the energy loss of the stress wave. Therefore, there is less need for position attenuation correction, and the position attenuation correction term is closer to 1. The larger the value, the closer the defect occurred to the end of the impact. This indicates that the precast pile structure defect is deeper and closer to the pile bottom. The stress wave travels a longer distance within the pile body, resulting in greater energy loss. Therefore, a position attenuation correction is more necessary, and in this case, the position attenuation correction term is greater than 1.

[0054] S5. Evaluate the bearing capacity of precast piles based on the pile integrity factor and bearing capacity index.

[0055] Specifically, a standard precast pile of the same specifications as the precast pile to be tested is obtained in good condition. The integrity factor of the standard precast pile is used as the integrity threshold, and the bearing capacity index of the standard precast pile is used as the bearing capacity index threshold. If the integrity factor of the precast pile to be tested is greater than the integrity threshold and the bearing capacity index is greater than the bearing capacity index threshold, then the bearing capacity of the precast pile to be tested is normal. If the integrity factor of the precast pile to be tested is less than or equal to the integrity threshold or the bearing capacity index is less than or equal to the bearing capacity index threshold, then the bearing capacity of the precast pile to be tested is abnormal. If the integrity factor of the precast pile to be tested is less than or equal to the integrity threshold and the bearing capacity index is less than or equal to the bearing capacity index threshold, then the bearing capacity of the precast pile to be tested is seriously abnormal.

[0056] This invention also discloses a concrete precast pile bearing capacity testing system, including a processor and a memory. The memory stores computer program instructions, which, when executed by the processor, implement a concrete precast pile bearing capacity testing method according to the present invention.

[0057] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

Claims

1. A method for testing the bearing capacity of precast concrete piles, characterized in that, include: Velocity and force signals are obtained from the acceleration and strain signals at the top of the precast pile; the velocity signal is decomposed into multiple IMF components and residual signals using an empirical mode decomposition algorithm. Based on the defect diagnosis set composed of high-frequency IMF components, the instantaneous energy spectrum is calculated; the moment corresponding to the largest peak in the instantaneous energy spectrum is the impact moment, the largest peak is the impact energy, the peak after the impact moment that is greater than the preset energy threshold and the duration is less than the preset time threshold is the candidate peak, the peak with the largest energy among the candidate peaks is the secondary energy peak, the value of the secondary energy peak is the defect energy, and the moment corresponding to the defect energy is the defect occurrence moment. Combine the IMF components outside the defect diagnosis set into a side resistance diagnosis set; obtain the energy sequence of each IMF component in the side resistance diagnosis set, and calculate the total energy of each energy sequence after the impact moment; obtain the maximum value in the force signal; determine the displacement change based on the difference in stable displacement before and after the impact of the residual signal; obtain the bearing capacity index based on the total energy of the side resistance diagnosis set, the impact energy, the maximum value of the force signal, and the total displacement change. Calculate the time it takes for the stress wave to reach the bottom of the pile; The pile integrity factor is obtained based on the defect energy, impact energy, defect occurrence time, and stress wave arrival time at the pile bottom. The bearing capacity of precast piles is tested based on the pile integrity factor and bearing capacity index.

2. The method for testing the bearing capacity of precast concrete piles according to claim 1, characterized in that, The process of obtaining velocity and force signals based on acceleration and strain signals at the top of the precast pile includes: acquiring acceleration and strain signals and obtaining the section modulus of the precast pile; integrating the acceleration signal to obtain the velocity signal; and obtaining the force signal based on the strain signal and the section modulus of the pile.

3. The method for testing the bearing capacity of precast concrete piles according to claim 1, characterized in that, The step of calculating the instantaneous energy spectrum based on the defect diagnosis set composed of high-frequency IMF components includes: selecting high-frequency IMF components to form a defect diagnosis set, applying Hilbert transform to each IMF component in the defect diagnosis set to obtain the corresponding analytical signal, calculating the square of the instantaneous amplitude of each analytical signal to form an energy sequence, and adding the energy sequences in pairs to obtain the instantaneous energy spectrum.

4. A method for testing the bearing capacity of precast concrete piles according to claim 1 or 3, characterized in that, The high-frequency IMF components are the three IMF components that are first decomposed from the velocity signal.

5. The method for testing the bearing capacity of precast concrete piles according to claim 1, characterized in that, The bearing capacity index satisfies the following relationship: ； In the formula, For bearing capacity index, For the moment of impact, The signal ends at the time. For the diagnosis of lateral resistance, the first The IMF component in the first The value at each moment, Representative of the side resistance diagnosis set The integral of the energy sequence of each IMF component after the impact time. To impact energy, The maximum value in the force signal. The change in displacement The number of IMF components in the side resistance diagnosis. To prevent division by zero, and These are the weights of the side resistance term and the end resistance term, respectively.

6. The method for testing the bearing capacity of precast concrete piles according to claim 5, characterized in that, The step of determining the displacement change based on the difference in stable displacement of the residual signal before and after the impact includes: taking the difference between the value of the residual signal at the moment of stable change after the impact and the value of the residual signal at the moment of stable change before the impact as the displacement change.

7. The method for testing the bearing capacity of precast concrete piles according to claim 6, characterized in that, The stable change time refers to the end time after the residual signal has completely decayed after the impact, and the start time before the impact.

8. The method for testing the bearing capacity of precast concrete piles according to claim 1, characterized in that, The pile integrity factor satisfies the following relationship: ； In the formula, For pile integrity factor, For defect energy, To impact energy, The time when the defect occurred. The time it takes for the stress wave to reach the bottom of the pile. It is an exponential function with the natural constant as its base. These are calibration coefficients.

9. The method for testing the bearing capacity of precast concrete piles according to claim 1, characterized in that, The method of testing the bearing capacity of precast piles based on pile integrity factor and bearing capacity index includes: if the pile integrity factor of the precast pile to be tested is greater than the integrity threshold and the bearing capacity index is greater than the bearing capacity index threshold, then the bearing capacity of the precast pile to be tested is normal.

10. A system for testing the bearing capacity of precast concrete piles, characterized in that, include: A processor and a memory, the memory storing computer program instructions that, when executed by the processor, implement a method for detecting the bearing capacity of precast concrete piles according to any one of claims 1-9.

Images