A method, device and storage medium for calculating the bending bearing capacity of steel pipe piles

Abstract

The present invention provides a method, device and storage medium for calculating the bending bearing capacity of steel pipe piles, which relates to the technical field of bending bearing capacity calculation. The present invention monitors the surface strain distribution and corrosion status of steel pipe piles in real time through distributed optical fiber and three-electrode system. First, the spatial gradient analysis method is used to identify the strain mutation area as the potential damage area, and the corrosion current density is measured by the polarization resistance method and corrected in combination with the strain threshold to calculate the cumulative corrosion depth. Secondly, the strain distribution is converted into an amplitude sequence using the rain flow counting method, and the fatigue damage degree is calculated in combination with the material S-N curve. The stress amplitude, chloride ion concentration and temperature difference data are integrated to construct a multi-damage coupling model to obtain the corrosion damage degree. Finally, a yield strength degradation model is established based on the service time, and the factors such as strength attenuation, fatigue damage, corrosion damage and cross-section loss are comprehensively considered. The current bearing capacity of the structure is evaluated by calculating the bending bearing capacity of the steel pipe column, and a graded early warning mechanism is set up.

Description

Technical Field

[0001] The present invention relates to the technical field of bending bearing capacity calculation, and in particular to a method, device and storage medium for calculating the bending bearing capacity of a steel pipe pile. Background Art

[0002] As key supporting structures for infrastructure such as marine engineering, ports, and cross-sea bridges, steel pipe piles are subjected to complex service environments for long periods of time, enduring dynamic loads such as waves, tides, and ship impacts. They also face the synergistic effects of environmental factors such as seawater corrosion, chloride ion penetration, and microbial erosion. This harsh multi-physics coupling environment can easily lead to localized corrosion, fatigue damage, and material degradation in steel pipe piles, which in turn weakens their bending bearing capacity and threatens the safety and durability of the overall structure. Especially in harsh environments such as deep sea and open ocean, damage to steel pipe piles evolves more rapidly, making it difficult for traditional inspection and maintenance methods to detect hidden dangers in a timely manner, increasing the risk of structural failure.

[0003] Currently, the monitoring and assessment of steel pipe piles primarily rely on discrete detection methods such as manual inspections, local strain gauges, or corrosion sensors. These methods suffer from limitations such as limited monitoring range, poor data continuity, and difficulty covering the entire cross-section. Furthermore, existing bearing capacity assessment models are mostly based on a single damage mechanism, such as considering only uniform corrosion or fatigue under static loads. These models fail to fully account for the impact of multiple factors on the performance degradation of steel pipe piles, resulting in significant deviations between calculated results and actual conditions. Although fiber optic sensing technology has been introduced into the field of structural health monitoring in recent years, the construction of a high-precision dynamic assessment model for bending bearing capacity, combining multi-source data such as electrochemical detection and environmental parameter monitoring, remains a pressing technical challenge.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a method and system for constructing a rice growth model based on salt stress, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for calculating the bending bearing capacity of a steel pipe pile, comprising the following steps:

[0008] Step 1: Distributed optical fiber and a three-electrode system are arranged on the surface of the steel pipe pile. The Bragg wavelength is monitored by the distributed optical fiber to obtain the strain distribution. The strain distribution is analyzed using the spatial gradient analysis method to identify potential damage areas.

[0009] Step 2: Activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain in the potential damage area exceeds the threshold. If it exceeds the threshold, apply the corrosion acceleration factor to correct the corrosion current density. Calculate the corrosion current velocity based on the corrected corrosion current density to obtain the cumulative corrosion depth.

[0010] Step 3: Convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles of the potential damage area at each strain amplitude is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected. The stress amplitude, chloride ion concentration and temperature difference variation amplitude data are integrated to construct a multi-damage coupling model to obtain the corrosion damage degree.

[0011] Step 4: Analyze the effect of the service life of the steel pipe pile on the yield strength to obtain the yield strength of the steel pipe pile at the current moment. Based on the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, determine the bending bearing capacity at the current moment. Analyze the relationship between the bending bearing capacity of the steel pipe pile at the current moment and the design value of the bending bearing capacity to determine the early warning mechanism.

[0012] Furthermore, identifying the potential damage area specifically includes:

[0013] The three-electrode system includes a working electrode, a counter electrode, and a reference electrode. An optical fiber sensor is arranged along the axial direction of the steel pipe pile to construct a uniaxial coordinate system. The Bragg wavelength is obtained by the optical fiber sensor, and the strain distribution is obtained by calculating the shift of the Bragg wavelength. The formula is as follows:

[0014] ;

[0015] in, is the strain of the steel pipe pile at the current moment, is the elastic-optical coefficient, is the initial Bragg wavelength, is the Bragg wavelength of the steel pipe pile at the current moment, x is the position coordinate variable of the steel pipe pile, Indicates the current moment;

[0016] The spatial gradient analysis method is used to analyze the strain gradient at each position of the steel pipe pile. The formula is as follows:

[0017] ;

[0018] in, is the strain gradient of the steel pipe pile at position x at the current moment;

[0019] The strain gradient at each position is judged. If , the location is classified as a potential damage area.

[0020] Furthermore, measuring the corrosion current density specifically includes:

[0021] Activate the three-electrode system in the potential damage area, apply potential perturbation and measure the current response. Record the potential shift and current response to obtain the polarization resistance, which is calculated as follows:

[0022] ;

[0023] ;

[0024] in, is the polarization resistance of the potential damage area at the current moment, d represents the position coordinate variable in the potential damage area, is the potential offset of the potential damage area d at the current moment, is the forward scanning potential of the potential damage area d at the current moment, is the negative scanning potential of the potential damage area d at the current moment, is the current response of the potential damage area d at the current moment, is the forward current response of the potential damage area d at the current moment, is the negative current response of position d in the potential damage area at the current moment;

[0025] The formula for calculating corrosion current density is as follows:

[0026] ;

[0027] in, is the corrosion current density at the potential damage area d at the current moment, B is the Stern-Geary constant, is the polarization resistance of position d in the potential damage area at the current moment.

[0028] Furthermore, obtaining the cumulative corrosion depth specifically includes:

[0029] Judge the strain of the potential damage area at the current moment. If , then the corrosion acceleration factor is not applied to the potential damage area d. , the corrosion current density is corrected using the corrosion acceleration factor, where is the strain at position d in the potential damage area at the current moment;

[0030] The corrosion current density at the current moment is corrected by the corrosion acceleration factor to obtain the corrected corrosion current density at the current moment. The formula is as follows:

[0031] ;

[0032] in, is the corrosion current density at the corrected potential damage zone d at the current moment, is the corrosion acceleration factor; if ,but ,like ,but , Indicates the strain at the current moment;

[0033] The corrosion rate formula is as follows:

[0034] ;

[0035] Where CR (d, t) is the corrosion rate of the potential damage area d at the current moment, EW is the metal electrochemical equivalent, is the material density;

[0036] The formula for calculating the cumulative corrosion depth is as follows:

[0037] ;

[0038] in, is the cumulative corrosion depth of the potential damage area d at the current moment, Indicates the potential damage area d is located at The corrosion rate at the time, Represents the time variable from the initial moment to the current moment, is the corrosion depth of the potential damage area d at the initial time, and the initial time is the starting time for the assessment of the bearing capacity of the steel pipe pile.

[0039] Furthermore, calculating the fatigue damage degree specifically includes:

[0040] The strain time series data of the potential damage area from the initial moment to the current moment are obtained. The strain time series data are processed based on the rain flow counting method to generate a strain amplitude sequence. Specifically, the strain time series data are arranged in time sequence to determine multiple maxima and minima. Starting from the first maximum value, the difference between the maximum value and the adjacent minimum value is used as the first strain amplitude. The number of cycles is recorded and all the maxima are traversed in turn to obtain the strain amplitude sequence, which is expressed as: ;

[0041] in, is the y-th strain amplitude in the strain amplitude sequence, y represents the index of the strain amplitude, represents the actual number of cycles corresponding to the y-th strain amplitude, Y is the total number of strain amplitude types, and y∈[1,Y];

[0042] Set k amplitude levels and determine the strain amplitude range corresponding to each amplitude level. For each strain amplitude, classify it into the corresponding amplitude level according to its numerical value, and accumulate the actual number of cycles corresponding to the strain amplitude to the total number of actual cycles of the amplitude level to which it belongs. Then, filter out the high strain amplitude level that causes fatigue damage to steel pipe piles from all amplitude levels.

[0043] Calculate the fatigue damage degree of the potential damage area at the current moment using the following formula:

[0044] ;

[0045] in, Indicates the potential damage area d position and the fatigue damage degree at the current moment, It represents the total number of actual cycles in amplitude level j from the initial moment to the current moment at the potential damage area d, where j represents the amplitude level. represents the minimum value of the set high strain amplitude level, k is the total number of amplitude levels, and , the larger the j value is, the larger the corresponding amplitude level is. ,k] range belongs to the high strain amplitude level, is the design life of the steel pipe pile, Indicates the length of time from the initial moment to the current moment. is the total number of fatigue cycles allowed in the design.

[0046] Furthermore, constructing the multi-damage coupling model specifically includes:

[0047] The strain amplitude at each location in the potential damage area is converted into stress amplitude using the following formula:

[0048] ;

[0049] in, is the stress amplitude at the potential damage area d at the current moment, is the elastic modulus of the material, is the strain amplitude at the potential damage area d at the current moment, that is, the maximum strain amplitude in the strain amplitude sequence;

[0050] The crack depth of the potential damage area at the current moment is measured by an eddy current detector. Combined with the stress amplitude, chloride ion concentration, and temperature change amplitude data, a multi-damage coupling model is constructed. The expression is as follows:

[0051] ;

[0052] ;

[0053] in, Indicates the corrosion damage degree of the potential damage area d at the current moment, is the stress intensity factor amplitude at the potential damage zone d at the current moment, which is used to quantify the stress concentration degree at the crack tip of the external load on the steel pipe pile. is the chloride ion concentration at the potential damage area d at the current moment, is the temperature variation amplitude at the location of the steel pipe pile, that is, the difference between the maximum and minimum temperatures within 24 hours before the current moment. is the fatigue crack growth coefficient, is the corrosion sensitivity coefficient, C is the chloride ion influence index, is the temperature change damage coefficient, m is the fatigue crack growth index, is the geometric correction factor, a is the crack depth at position d in the potential damage area at the current moment.

[0054] Furthermore, obtaining the bending bearing capacity at the current moment specifically includes:

[0055] According to the service life of the steel pipe pile and the benchmark life, the yield strength of the steel pipe pile at the current moment is obtained. The calculation formula is as follows:

[0056] ;

[0057] in, is the yield strength at the current moment, is the standard yield strength, For the duration of use, is the baseline lifespan, is the degradation rate coefficient;

[0058] According to the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, the bending bearing capacity of the steel pipe pile at the current moment is obtained. The calculation formula is as follows:

[0059] ;

[0060] in, is the bending bearing capacity of the potential damage zone d at the current moment, is the initial bending bearing capacity of the steel pipe pile, is the fatigue damage degree of the potential damage area d at the current moment, is the corrosion damage degree of the potential damage area d at the current moment, is the fatigue-corrosion interaction factor, is the cumulative corrosion depth of the potential damage area d at the current moment, is the outer diameter of the steel pipe pile;

[0061] Traverse the bending bearing capacity of all positions in the potential damage zone of the steel pipe pile, and take the minimum value of the bending bearing capacity in all potential damage zones as the bending bearing capacity of the steel pipe pile at the current moment. Compare the bending bearing capacity of the steel pipe pile at the current moment with the design value. If the bending bearing capacity drops to 85% of the design value, a yellow warning is issued. If the bending bearing capacity drops to 70% of the design value, a red warning is issued. The damage rate is monitored. If the damage rate increases by 200% compared with the previous moment, an emergency warning is issued.

[0062] The present invention further provides a device for calculating the bending bearing capacity of a steel pipe pile, wherein the device is used to implement the above-mentioned method for calculating the bending bearing capacity of a steel pipe pile, and comprises:

[0063] The potential damage area identification module is used to arrange a distributed optical fiber and a three-electrode system on the surface of the steel pipe pile. The distributed optical fiber monitors the Bragg wavelength to obtain the strain distribution, and uses the spatial gradient analysis method to analyze the strain distribution to identify potential damage areas.

[0064] The corrosion depth determination module is used to activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain of the potential damage area exceeds the threshold. If the threshold is exceeded, the corrosion current density is corrected by applying the corrosion acceleration factor. The corrosion current velocity is calculated based on the corrected corrosion current density to obtain the cumulative corrosion depth;

[0065] The multi-damage coupling assessment module is used to convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles at each strain amplitude in the potential damage area is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected, and a multi-damage coupling model is constructed by integrating the stress amplitude, chloride ion concentration and temperature difference variation amplitude data to obtain the corrosion damage degree.

[0066] The bearing capacity calculation and early warning module is used to analyze the impact of the service life of steel pipe piles on the yield strength to obtain the yield strength of the steel pipe piles at the current moment. Based on the yield strength, fatigue damage degree, corrosion damage degree and cumulative corrosion depth of the steel pipe piles at the current moment, the current bending bearing capacity is determined. The relationship between the current bending bearing capacity of the steel pipe piles and the design value of the bending bearing capacity is analyzed to determine the early warning mechanism.

[0067] The present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned method for calculating the bending bearing capacity of a steel pipe pile.

[0068] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0069] The present invention achieves high-precision identification of the strain distribution of the entire cross-section of the steel pipe pile and precise positioning of the potential damage area through coordinated monitoring by distributed optical fiber and a three-electrode system, overcoming the limitations of traditional local detection technology. The corrosion rate is corrected in combination with the polarization resistance method, and a multi-damage coupling model is introduced to cover fatigue, chloride ion corrosion and temperature difference effects, which significantly improves the assessment accuracy of corrosion depth and fatigue damage. Further integration of the time-varying yield strength model can dynamically calculate the current bending bearing capacity and generate an early warning signal by comparing it with the design value in real time. This method not only solves the problem of inaccurate bearing capacity assessment under the coupling of multiple factors, but also greatly reduces manual dependence through intelligent monitoring and calculation, providing reliable technical support for the long-term safe operation and maintenance of steel pipe piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 Schematic diagram of the overall method flow of the present invention;

[0071] Figure 2 Schematic diagram of the relationship between yield strength and bending bearing capacity;

[0072] Figure 3 Schematic diagram of the relationship between fatigue damage degree and bending bearing capacity;

[0073] Figure 4 Schematic diagram of the relationship between corrosion damage degree and flexural bearing capacity;

[0074] Figure 5 Schematic diagram of the relationship between cumulative corrosion depth and bending bearing capacity;

[0075] Figure 6 Schematic diagram of the module structure of the steel pipe pile bending bearing capacity calculation device in the present invention. DETAILED DESCRIPTION

[0076] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0077] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0078] Example:

[0079] See also Figure 1-Figure 5 , the present invention provides a technical solution:

[0080] A method for calculating the bending bearing capacity of a steel pipe pile, comprising the following steps:

[0081] Step 1: Distributed optical fiber and a three-electrode system are arranged on the surface of the steel pipe pile. The Bragg wavelength is monitored by the distributed optical fiber to obtain the strain distribution. The strain distribution is analyzed using the spatial gradient analysis method to identify potential damage areas.

[0082] In this embodiment, identifying the potential damage area specifically includes:

[0083] The three-electrode system includes a working electrode, a counter electrode, and a reference electrode. The working electrode can be a Q235 steel microelectrode, the counter electrode can be a platinum wire ring, and the reference electrode can be Ag / AgCl (seawater type). Fiber optic sensors are arranged along the axial direction of the steel pipe pile to construct a single-axis coordinate system with a spacing of 30 cm. The spacing should be more dense in the bending moment sensitive area, such as 15 cm. The Bragg wavelength is obtained by the fiber optic sensor, and the strain distribution is obtained by calculating the offset of the Bragg wavelength. The formula is as follows:

[0084] ;

[0085] in, is the strain of the steel pipe pile at the current moment, is the elastic-optical coefficient, here we take =0.22, determined by the characteristics of the optical fiber material, is the initial Bragg wavelength, take , is the typical communication band wavelength, is the Bragg wavelength of the steel pipe pile at the current moment, x is the position coordinate variable of the steel pipe pile, Indicates the current moment;

[0086] The spatial gradient analysis method is used to analyze the strain gradient at each position of the steel pipe pile. The formula is as follows:

[0087] ;

[0088] in, is the strain gradient of the steel pipe pile at position x at the current moment;

[0089] The strain gradient at each position is judged. If , the location is classified as a potential damage area.

[0090] Through the coordinated arrangement of distributed optical fiber and three-electrode system, real-time and high-precision monitoring of the strain distribution on the surface of steel pipe piles is achieved, and potential damage areas are accurately identified based on spatial gradient analysis. The technical effect of this step is: on the one hand, by capturing the Bragg wavelength shift and calculating the strain gradient through optical fiber sensors, stress concentration or structural abnormality areas can be quickly located, such as strain gradients exceeding 10 On the other hand, combined with the electrochemical data of the three-electrode system, the corrosion activity of the damaged area can be further verified, providing reliable damage characteristic parameters for subsequent bending bearing capacity calculations, significantly improving the accuracy and timeliness of steel pipe pile health status assessments.

[0091] Step 2: Activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain in the potential damage area exceeds the threshold. If it exceeds the threshold, apply the corrosion acceleration factor to correct the corrosion current density. Calculate the corrosion current velocity based on the corrected corrosion current density to obtain the cumulative corrosion depth.

[0092] In this embodiment, measuring the corrosion current density specifically includes:

[0093] Activate the three-electrode system in the potential damage area, apply potential perturbation and measure the current response. Record the potential shift and current response to obtain the polarization resistance, which is calculated as follows:

[0094] ;

[0095] ;

[0096] in, is the polarization resistance of the potential damage area at the current moment, d represents the position coordinate variable in the potential damage area, is the potential offset of the potential damage area d at the current moment, is the forward scanning potential of the potential damage area d at the current moment, is the negative scanning potential of the potential damage area d at the current moment, is the current response of the potential damage area d at the current moment, is the forward current response of the potential damage area d at the current moment, is the negative current response of position d in the potential damage area at the current moment.

[0097] In the polarization resistance measurement method, the acquisition of the positive scanning potential and the negative scanning potential is achieved through the dynamic potential perturbation test of the three-electrode system. The specific process is as follows: first, the potentiostat applies a small-amplitude linear polarization scan starting from the natural corrosion potential to the working electrode (potential damage area). During the positive scan, the potential increases linearly with time (usually within a deviation of +10mV), and the current response is recorded synchronously. ; Then, reverse scanning is performed, the potential drops from the peak value back to the initial value and continues to decrease linearly by the same amplitude, while recording the negative current response The polarization curve data obtained by this bidirectional scanning not only avoids the system polarization hysteresis error that may be caused by single unidirectional polarization, but also verifies the stability of the measurement through the symmetry of positive and negative data. Finally, the absolute value of the potential offset of the two scans is added to obtain the total potential offset. , ensuring that complete electrochemical response information is included in the polarization resistance calculation.

[0098] The formula for calculating corrosion current density is as follows:

[0099] ;

[0100] in, is the corrosion current density at the potential damage area d at the current moment, B is the Stern-Geary constant, for example, for low carbon steel B=26mV, is the polarization resistance of position d in the potential damage area at the current moment.

[0101] Polarization resistance refers to the ratio of the potential change to the current response when the metal electrode is slightly polarized. Its essence is the resistance reflected by the kinetics of corrosion on the electrode surface. The smaller the value, the lower the resistance reflected by the corrosion of the electrode surface, the easier it is for the corrosion current to pass through, the higher the corrosion rate, and the greater the corresponding corrosion current density; The larger the value, the more the corrosion reaction is inhibited, such as the formation of a passivation film or the effect of a corrosion inhibitor. The lower the corrosion rate, the smaller the corresponding corrosion current density.

[0102] In this embodiment, obtaining the cumulative corrosion depth specifically includes:

[0103] Judge the strain of the potential damage area at the current moment. If , the unit is , then the corrosion acceleration factor is not applied to the potential damage area d. , the corrosion current density is corrected using the corrosion acceleration factor, where is the strain at position d in the potential damage area at the current moment;

[0104] The corrosion current density at the current moment is corrected by the corrosion acceleration factor to obtain the corrected corrosion current density at the current moment. The formula is as follows:

[0105] ;

[0106] in, is the corrosion current density at the corrected potential damage zone d at the current moment, is the corrosion acceleration factor; if ,but , that is, the corrosion rate increases by 20%. ,but , Indicates the strain at the current moment.

[0107] When steel pipe piles are subjected to cyclic loads such as waves and wind loads, local strain may increase significantly, such as Therefore, a corrosion acceleration factor is introduced to correct this. The corrected corrosion current density is more consistent with engineering practice, especially for structures subjected to alternating loads. The corrected corrosion rate directly affects the cumulative corrosion depth, thereby accurately reflecting the extent to which cross-sectional loss weakens the bending resistance of steel pipe piles, supporting the subsequent development of bearing capacity degradation models.

[0108] The corrosion rate formula is as follows:

[0109] ;

[0110] Among them, CR (d, t) is the corrosion rate of the potential damage area d at the current moment, EW is the metal electrochemical equivalent, for example, Q235 steel is 27.925, is the material density, for example, 7.87 for steel; as the corrosion current density increases, the corrosion rate also increases.

[0111] The formula for calculating the cumulative corrosion depth is as follows:

[0112] ;

[0113] in, is the cumulative corrosion depth of the potential damage area d at the current moment, Indicates the potential damage area d is located at The corrosion rate at the time, Represents the time variable from the initial moment to the current moment, is the corrosion depth of the potential damage area d at the initial time, and the initial time is the starting time for the assessment of the bearing capacity of the steel pipe pile.

[0114] The cumulative corrosion depth, as the dependent variable, reflects the total thickness of material lost due to corrosion at the potential damage zone d of the steel pipe pile from the initial moment to the current moment t. Its physical meaning is the time-varying extension of the corrosion damage at spatial location d, directly quantifying the degree of strength degradation in the structural section. The corrosion rate CR(d,t), as the core independent variable, directly influences the cumulative corrosion depth through integration. The corrosion rate itself is determined by the corrosion current density and material properties, while the corrosion current density is in turn regulated by the environmental corrosiveness and local strain conditions, namely, the corrosion acceleration factor. Therefore, the corrosion rate integrates the coupled effects of the environment, the mechanical state of the material, and the electrochemical properties, and its temporal variation directly determines the growth trend of the cumulative corrosion depth. The integration process shows that the higher the instantaneous value of the corrosion rate, or the longer the high corrosion rate persists, the faster the cumulative corrosion depth increases. The dependent variable, cumulative corrosion depth, exhibits a strict positive correlation with the independent variable, corrosion rate, and this relationship has a cumulative effect over time. An increase in the corrosion rate (e.g., due to strain exceeding the threshold, resulting in α = 1.2) directly increases the value of the integrand, thereby accelerating the growth of the cumulative corrosion depth. Conversely, a decrease in the corrosion rate slows the growth of the cumulative corrosion depth. Due to the cumulative nature of the integral operation, even a sudden change in the corrosion rate at a certain moment will continue to affect the subsequent cumulative depth, making the cumulative corrosion depth retain and depend on changes in the corrosion rate. This relationship ensures that the model accurately reflects the irreversibility and gradual nature of corrosion damage in actual engineering.

[0115] Step 3: Convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles of the potential damage area at each strain amplitude is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected. The stress amplitude, chloride ion concentration and temperature difference variation amplitude data are integrated to construct a multi-damage coupling model to obtain the corrosion damage degree.

[0116] In this embodiment, calculating the fatigue damage degree specifically includes:

[0117] The strain time series data of the potential damage area from the initial moment to the current moment are obtained. The strain time series data are processed based on the rain flow counting method to generate a strain amplitude sequence. Specifically, the strain time series data are arranged in time sequence to determine multiple maxima and minima. Starting from the first maximum value, the difference between the maximum value and the adjacent minimum value is used as the first strain amplitude. The number of cycles is recorded and all the maxima are traversed in turn to obtain the strain amplitude sequence, which is expressed as: ;

[0118] in, is the y-th strain amplitude in the strain amplitude sequence, y represents the index of the strain amplitude, represents the actual number of cycles corresponding to the y-th strain amplitude, Y is the total number of strain amplitude types, and y∈[1,Y];

[0119] Set k amplitude levels, and determine the strain amplitude range corresponding to each amplitude level. For each strain amplitude, classify it into the corresponding amplitude level according to its numerical value, and accumulate the actual number of cycles corresponding to the strain amplitude to the total actual number of cycles of the amplitude level to which it belongs. Finally, screen out the high strain amplitude level that causes fatigue damage to steel pipe piles from all amplitude levels.

[0120] For example, assuming that the strain amplitude of the potential damage zone of the steel pipe pile is in the range [0,2000], the unit is , now set k=5, and divide the strain amplitude interval into equal intervals and non-equal intervals respectively. Scheme 1: Equal interval division, the amplitude levels are j=1, 2, 3, 4, 5 from small to large, j=1 indicates the lowest amplitude level, j=5 indicates the highest amplitude level. j=1, the corresponding strain amplitude interval is [0,400); j=2, the corresponding strain amplitude interval is [400,800); j=3, the corresponding strain amplitude interval is [800,1200); j=4, the corresponding strain amplitude interval is [1200,1600); j=5, the corresponding strain amplitude interval is [1600,2000]. Scheme 1 is suitable for cases where the strain distribution is relatively uniform, and the interval of each level is the same. If set , then j=4 and 5 belong to high strain amplitude levels and participate in the calculation of fatigue damage degree. Scheme 2: Non-equal interval division, the amplitude levels are j=1, 2, 3, 4, 5 from small to large, j=1 indicates the lowest amplitude level, j=5 indicates the highest amplitude level. j=1, the corresponding strain amplitude interval is [0,200); j=2, the corresponding strain amplitude interval is [200,500); j=3, the corresponding strain amplitude interval is [500,1000); j=4, the corresponding strain amplitude interval is [1000,1500); j=5, the corresponding strain amplitude interval is [1500,2000]. Scheme 2 is suitable for situations where there are more low strain cycles, but a few high strain cycles have a significant impact, such as wave impact loads. If it is set , then j=3, 4, and 5 belong to high strain amplitude levels and participate in the calculation of fatigue damage degree.

[0121] Calculate the fatigue damage degree of the potential damage area at the current moment using the following formula:

[0122] ;

[0123] in, Indicates the fatigue damage degree of the potential damage area d at the current moment, It represents the total number of actual cycles in amplitude level j from the initial moment to the current moment at the potential damage area d, where j represents the amplitude level. represents the minimum value of the set high strain amplitude level, k is the total number of amplitude levels, and , the larger the j value is, the larger the corresponding amplitude level is. ,k] range belongs to the high strain amplitude level, The design life of the steel pipe pile is 30 years, Indicates the length of time from the initial moment to the current moment. is the total number of fatigue cycles allowed in the design.

[0124] The total number of fatigue cycles allowed by the design is obtained by converting the corresponding strain value into stress value, and querying the SN curve corresponding to the material through the stress value to obtain the total number of fatigue cycles allowed. For example, the typical reference value is Q235 steel, the strain amplitude is 380, and the typical ; The strain amplitude is 76, typical ; The strain amplitude is 1000, typical ; The strain amplitude is 1430, typical .

[0125] The fatigue damage degree, as the dependent variable, reflects the degree of cumulative fatigue damage at the potential damage zone due to cyclic loading at the current moment. Its physical meaning is a macroscopic quantitative representation of the microscopic damage to the material after the structure undergoes high-strain amplitude cycles during service, with larger values ​​indicating more severe fatigue damage. The actual total number of cycles at the high-strain amplitude level, the independent variable, is correlated with the dependent variable through the core assumptions of Miner's linear cumulative damage theory. The strain amplitude series extracted by the rainflow counting method is statistically classified by amplitude level, and its value directly depends on the intensity and frequency of the cyclic loads to which the structure is subjected. The design life and assessment duration constitute the time scale normalization factor, which converts the number of cycles in different service periods into equivalent life percentages. As the benchmark of material fatigue resistance, it determines the critical conditions of unit damage. These independent variables together constitute the damage ratio framework of "actual consumption life / theoretical usable life", where is the active quantity that drives damage accumulation, and the remaining parameters provide a standardized calculation basis. It exhibits a piecewise linear positive correlation with the independent variable. For the selected high-strain amplitude levels, an increase in the total number of actual cycles directly leads to a linear increase in the damage severity, and the damage contributions of different amplitude levels are additive. An increase in the evaluation duration is usually accompanied by a cumulative increase in the total number of actual cycles, indirectly strengthening the positive correlation. However, an increase in the total number of fatigue cycles allowed by the design (improved material fatigue resistance) as the denominator weakens the damage severity, exhibiting an inverse correlation. This relationship conforms to the basic principle of the Palmgren-Mainer linear damage law and effectively reflects the physical nature of high-stress cycles in engineering practice, which are more likely to induce fatigue damage.

[0126] In this embodiment, constructing the multi-damage coupling model specifically includes:

[0127] The strain amplitude at each location in the potential damage area is converted into stress amplitude using the following formula:

[0128] ;

[0129] in, is the stress amplitude at the potential damage area d at the current moment, is the elastic modulus of the material, is the strain amplitude at the potential damage area d at the current moment, that is, the maximum strain amplitude in the strain amplitude sequence. Here, the maximum strain amplitude is taken to conservatively assess the damage.

[0130] The crack depth of the potential damage area at the current moment is measured by an eddy current detector. Through electrochemical sensor monitoring, chloride ion selective electrodes or optical fiber chemical sensors are pre-buried or attached at the potential damage area to collect the chloride ion concentration at the potential damage area. Digital temperature sensors such as DS18B20 and PT100 are deployed at key locations of steel pipe piles, such as tidal range areas, mud surface lines or exposed sections, to record temperature data in real time, extract the highest and lowest temperatures within 24 hours, and use the difference between the two as the temperature change amplitude, that is, , is the maximum temperature, is the lowest temperature. If there is more than one digital temperature sensor on the steel pipe pile, the average temperature change amplitude of all sensors is taken as the temperature change amplitude at the location of the steel pipe pile. Combining the stress amplitude, chloride ion concentration and temperature change amplitude data, a multi-damage coupling model is constructed, and the expression is as follows:

[0131] ;

[0132] ;

[0133] in, Indicates the corrosion damage degree of the potential damage area d at the current moment, is the stress intensity factor amplitude at the potential damage zone d at the current moment, which is used to quantify the stress concentration degree at the crack tip of the external load on the steel pipe pile. is the chloride ion concentration at the potential damage area d at the current moment, is the temperature variation amplitude at the location of the steel pipe pile, that is, the difference between the maximum and minimum temperature at the current moment and within the previous 24 hours. is the fatigue crack growth coefficient, is the corrosion sensitivity coefficient, C is the chloride ion influence index, is the temperature change damage coefficient, m is the fatigue crack growth index, is the geometric correction factor, a is the crack depth at the potential damage zone d at the current moment. For example, the typical value range refers to experimental data. The value range is [ , ], The value range is [ , ], The value range is [ , ], and in the above multi-damage coupling model expression, it is set ,like 、 、 , which is mainly due to the physical characteristics of different damage mechanisms and the intensity of environmental effects. High concentrations of chloride ions will significantly damage the passive film of steel, causing rapid pitting and stress corrosion, and the exponential term in the model will amplify its influence; fatigue crack growth has the second highest weight, because although fatigue damage grows with the power of the stress intensity factor ΔK, it requires a large number of accumulated cycles to appear; temperature change has the smallest weight, because the thermal stress generated by the daily temperature difference is relatively limited, that is, the thermal expansion coefficient of steel is small, and its influence only acts in the form of the square of ΔT. This relationship has been verified by accelerated tests and field data calibration in marine environments, reflecting that chloride ion corrosion is usually the dominant damage mechanism in marine engineering, and the contribution of temperature changes is relatively weak. Regarding the calibration method of the weight coefficient, the weight coefficient can be obtained through fatigue tests, such as three-point bending, and fitting the Paris formula parameters. By measuring the relationship between corrosion current density and chloride ion concentration through salt spray test or electrochemical polarization curve, the weight coefficient can be derived. Through thermal cycle test, the weight coefficient can be obtained .

[0134] The construction of the multi-damage coupling model fully considers the complex degradation mechanisms faced by steel pipe piles in actual service environments. Its rationality is mainly reflected in the quantitative modeling of the synergistic effects of fatigue, corrosion, and environmental factors. Traditional structural health monitoring methods often analyze single damage mechanisms in isolation, such as only evaluating fatigue crack propagation or uniform corrosion rates, while ignoring the mutual promotion between different damage forms. However, in some harsh environments, the degradation of steel pipe piles is often the result of the combined action of multiple factors: cyclic loading causes fatigue crack initiation and propagation, chloride ion penetration accelerates local corrosion, and temperature fluctuations further affect the mechanical properties and corrosion rate of the material. This model incorporates the three key damage drivers of fatigue crack propagation, chloride ion concentration, and temperature variation amplitude into a unified framework in the form of differential equations. Its physical basis is that the three correspond to mechanical, chemical, and thermodynamic damage mechanisms, respectively, and a comprehensive analysis is conducted through the significant coupling effect between these factors.

[0135] By incorporating a stress intensity factor amplitude term, the multi-damage coupling model quantifies the fatigue crack growth behavior under alternating stresses. The inclusion of geometric correction factors and crack depth makes the calculated results more accurate with actual defect morphology, avoiding the oversimplification of crack shape often observed in traditional analytical methods. Secondly, chloride ion concentration is incorporated into the model calculation as an exponential function, reflecting the nonlinear acceleration of chloride ions on the corrosion rate and enabling differentiation of corrosiveness differences between different sea areas. Finally, the squared temperature amplitude term captures material degradation caused by thermal cycling, including microcrack growth induced by thermal stress and the temperature-induced corrosion rate enhancement. From an engineering perspective, this model significantly improves the accuracy of remaining life prediction for steel pipe piles. By inputting real-time monitoring data (such as strain, Cl⁻ concentration, and temperature), the model dynamically updates the corrosion damage degree, thereby identifying high-risk damage areas. For example, in areas such as the splash zone, which experience simultaneous high ∆K, high Cl⁻, and large ∆T, the model outputs a higher damage growth rate, consistent with the actual engineering observation that these areas are more susceptible to premature failure. Furthermore, model parameters can be calibrated through laboratory accelerated testing or field data inversion, adapting them to different material systems and environmental conditions, providing differentiated support for operation and maintenance decisions. This modeling approach, which integrates multi-source data, overcomes the limitations of traditional single-mechanism models and provides a more reliable analysis tool for the full lifecycle management of steel pipe piles.

[0136] Step 4: Analyze the effect of the service life of the steel pipe pile on the yield strength to obtain the yield strength of the steel pipe pile at the current moment. Based on the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, determine the bending bearing capacity at the current moment. Analyze the relationship between the bending bearing capacity of the steel pipe pile at the current moment and the design value of the bending bearing capacity to determine the early warning mechanism.

[0137] In this embodiment, obtaining the bending bearing capacity at the current moment specifically includes:

[0138] According to the service life of the steel pipe pile and the benchmark life, the yield strength of the steel pipe pile at the current moment is obtained. The calculation formula is as follows:

[0139] ;

[0140] in, is the yield strength at the current moment, The standard yield strength of steel pipe piles can be obtained by laboratory tensile test or portable Leeb hardness tester. For the duration of use, is the baseline lifespan, The degradation rate coefficient can be obtained by making a standard time for the target material and conducting aging tests in an accelerated test chamber that simulates the actual service environment. It can also be obtained by referring to empirical values ​​in the literature. For example, in a mild environment (such as inland fresh water), the value range is [1.2, 1.5], in the marine atmosphere zone, the value range is [1.5, 1.8], and in the splash zone or underwater zone, the value range is [1.8, 2.2]. The yield strength reflects the actual yield strength of the steel pipe pile at the current moment t. Its physical meaning is the ability of the material to resist plastic deformation after long-term service. The technical effect of this parameter is to quantify the influence of time factors on the attenuation of the mechanical properties of the material, so that the calculation of the bending bearing capacity can dynamically reflect the aging state of the structure, avoiding the direct use of the initial yield strength. The problem of overestimation of bearing capacity caused by the load-bearing capacity is solved, which provides a time-varying strength benchmark for structural safety assessment. For example, if a steel pipe pile with 20 years of service =355MPa, calculated =284MPa, the subsequent bearing capacity analysis needs to be based on this degraded strength value.

[0141] Independent variable and The setting reflects the correlation between material strength degradation and service life and environmental conditions. It represents the ratio of service time to reference life, reflecting the degree of time-dependent damage experienced by the structure; As the degradation rate coefficient, it integrates the influence of external factors such as environmental corrosiveness and load frequency on the aging rate. The combination of the two forms a power function relationship, which can accurately describe the nonlinear attenuation law of material strength over time. With independent variables There is a negative correlation, that is, the greater the proportion of service time, the more significant the loss of yield strength. This relationship is achieved through the interaction of coefficients and power functions to achieve nonlinear regulation. near hour, May drop to 80% of the total strength, which is consistent with the typical strength attenuation range at the end of the service life of engineering structures. As an exponential term coefficient, its increase will strengthen the promoting effect of time on intensity decay, for example Increasing from 1.5 to 2.0 will also The strength loss under different corrosion environments is increased by about 30%. This design enables the model to flexibly adapt to the strength prediction requirements of different corrosion environments.

[0142] According to the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, the bending bearing capacity of the steel pipe pile at the current moment is obtained. The calculation formula is as follows:

[0143] ;

[0144] in, is the bending bearing capacity of the potential damage zone d at the current moment, is the initial bending bearing capacity of the steel pipe pile, is the fatigue damage degree of the potential damage area d at the current moment, is the corrosion damage degree of the potential damage area d at the current moment, is the fatigue-corrosion interaction factor, is the cumulative corrosion depth of the potential damage area d at the current moment, is the outer diameter of the steel pipe pile; the fatigue-corrosion interaction factor is calculated based on the damage equivalence principle by comparing the SN curve deviation between the simple fatigue group and the corrosion fatigue group in the laboratory stage. The typical range is [0.3, 0.5].

[0145] The flexural capacity reflects the residual flexural bearing capacity of the potentially damaged zone d of the steel pipe pile at the current time t. Its physical meaning is the maximum bending moment that this zone can still withstand after experiencing material degradation, fatigue damage, and corrosion. The technical benefit of this parameter is that it provides a direct criterion for determining the structural safety status by quantifying the loss of bearing capacity due to the coupling of multiple factors.

[0146] Independent variables in formulas 、 、 and Four types of degradation mechanisms, namely material strength, fatigue damage, corrosion damage and cross-section loss, are characterized respectively. Their relevance stems from the synergistic mechanism of these factors in actual engineering. The time-varying degradation of the material's constitutive properties directly affects the cross-section's plastic resistance. The fatigue damage and corrosion damage degrees, through the interaction factor η, reflect the mutual promotion of fatigue and corrosion (e.g., corrosion pits accelerate fatigue crack propagation). The cumulative corrosion depth describes the nonlinear weakening of the cross-section modulus due to corrosion depth. This combination of variables ensures that the model captures the full dimensional degradation of steel pipe piles, from material property degradation to geometric defects. For example, even if fatigue damage is low in a region, significant corrosion depth can still lead to a significant reduction in bearing capacity.

[0147] Flexural capacity and current yield strength There is a positive correlation. As the service time increases, the yield strength will gradually decrease. This is because the steel experiences lattice defect accumulation and microstructural degradation in long-term service, which weakens the material's ability to resist plastic deformation. Therefore, the greater the yield strength, the greater the bending bearing capacity; conversely, the smaller the bending bearing capacity. Fatigue damage and corrosion damage jointly affect the bearing capacity through the fatigue-corrosion interaction factor. The increase of these two damage degrees will lead to A decrease in this term, or an increase in fatigue or corrosion damage, will also lead to a decrease in this term, thereby reducing the flexural capacity. This is because fatigue damage triggers the initiation and propagation of microcracks, while corrosion damage exacerbates the loss of the material's effective cross-sectional area. The synergistic effect of these two factors accelerates the degradation of bearing capacity. Therefore, the greater the fatigue and corrosion damage, the lower the flexural capacity; conversely, the greater the flexural capacity. The cumulative corrosion depth exerts a nonlinear effect on the flexural capacity through a squared term. As the cumulative corrosion depth increases, this squared term decreases rapidly, and the flexural capacity also decreases significantly. This is because corrosion not only reduces the effective cross-sectional area of ​​the component but also changes the moment of inertia. As the pipe wall becomes thinner, the cross-sectional ability to resist bending moments decreases in a squared relationship. The outer diameter of the steel pipe is used as a normalizing parameter; a larger value indicates a smaller relative impact on the flexural capacity for the same corrosion depth. Therefore, as the cumulative corrosion depth increases, the flexural capacity of the steel pipe pile decreases; conversely, the flexural capacity increases.

[0148] The construction of the above-mentioned flexural capacity formula has clear physical significance and engineering rationality, and its structure fully considers the main degradation mechanisms and their interactions of steel pipe piles in actual service environments. The formula takes the initial flexural capacity as a benchmark and, by introducing key variables such as current yield strength, fatigue damage, corrosion damage, and cumulative corrosion depth, systematically reflects the effects of material property degradation, cumulative fatigue damage, corrosion degradation, and cross-sectional loss on flexural capacity. This hierarchical correction method conforms to the basic principles of structural mechanics, namely that flexural capacity is primarily determined by material strength, cross-sectional geometric properties, and damage state. Therefore, the formula can more comprehensively characterize the evolution of the bearing capacity of steel pipe piles during long-term service.

[0149] The current yield strength degradation model in the formula uses a power function, a representation consistent with the strength decay trend of steel after long-term service. The yield strength decreases with increasing service life, consistent with microstructural degradation of steel under environmental loads (such as changes in dislocation density and grain boundary weakening). The introduction of a benchmark life and degradation rate coefficient allows the model to adapt to material degradation patterns under diverse environmental conditions, improving the applicability of the formula. Fatigue damage and corrosion damage affect flexural capacity through a linear combination, reflecting the synergistic effect of fatigue and corrosion. Fatigue damage primarily results from crack initiation and propagation under cyclic loading, while corrosion damage involves material loss and stress concentration caused by electrochemical reactions. The introduction of an interaction factor reflects that the two effects are not independent but rather mutually reinforcing: corrosion accelerates fatigue crack propagation, while areas of fatigue stress concentration are more susceptible to localized corrosion. Accounting for this coupled effect enables the formula to more accurately predict bearing capacity degradation under complex environments. The influence of the cumulative corrosion depth is reflected in a quadratic term, a form consistent with the mechanical properties of the moment of inertia of a thin-walled circular tube section. Corrosion causes pipe wall thinning, reducing not only the effective cross-sectional area but also the cross-sectional bending stiffness. Due to the square relationship between the moment of inertia and the wall thickness, the effect of corrosion on bending capacity exhibits a nonlinear, accelerating trend: the deeper the corrosion, the faster the bearing capacity decreases. This expression has been widely validated in engineering practice and reasonably reflects the variation in the residual bearing capacity of steel pipe piles in corrosive environments.

[0150] Overall, the construction of this flexural capacity formula not only considers the time-varying degradation of material properties but also incorporates the coupling effects of major damage mechanisms such as fatigue and corrosion. Furthermore, it ensures the accuracy of the calculation results through reasonable mechanical relationships, such as the yield strength degradation model and the influence of the section moment of inertia. Therefore, this formula not only has a theoretical basis but also possesses engineering applicability, providing a reliable calculation method for the long-term performance evaluation and life prediction of steel pipe piles.

[0151] In this example, 30 sets of sample data for calculating the bending bearing capacity of the potential damage zone of steel pipe piles were collected. Here, the standard yield strength was set to 355 MPa, the reference life was set to 50 years, the degradation rate coefficient was set to 1.2, the initial bending bearing capacity value was set to 1000 kN·m, the fatigue corrosion interaction factor was set to 0.4, and the outer diameter of the steel pipe pile was set to 800 mm. The specific sample data are shown in the following table:

[0152] Table 1: Numerical table of relevant sample data

[0153]

[0154] Reference Figure 2-Figure 5, and the data in the above table show that with the increase of yield strength, the bending bearing capacity of the potential damage zone of the steel pipe pile is also increasing, and the corresponding bending bearing capacity of the steel pipe pile is also increasing, and the two show a positive correlation; while with the increase of fatigue damage degree, corrosion damage degree and cumulative corrosion depth, the bending bearing capacity of the potential damage zone is decreasing, and the bending bearing capacity of the steel pipe pile is also decreasing, and the fatigue damage degree, corrosion damage degree and cumulative corrosion depth are negatively correlated with the bending bearing capacity.

[0155] The bending capacity of all locations in the potential damage zone of the steel pipe pile is traversed. The minimum bending capacity value in all potential damage zones is used as the bending capacity of the steel pipe pile at the current moment. The bending capacity of the steel pipe pile at the current moment is compared with the design value. If the bending capacity drops to 85% of the design value, a yellow warning is issued. If the bending capacity drops to 70% of the design value, a red warning is issued. The damage rate is also monitored. If the damage rate increases by 200% compared to the previous moment, an emergency warning is issued. The design value can be obtained from the steel pipe pile production report.

[0156] By dynamically quantifying the time-varying degradation of the yield strength of steel pipe piles and the attenuation of their flexural bearing capacity under the coupling of multiple damages, real-time early warning and precise control of the structural safety status are achieved. The technical effect is reflected in the integration of multi-dimensional degradation mechanisms such as material performance aging, fatigue, corrosion synergistic damage, and cross-sectional geometric degradation into an explicit expression of the flexural bearing capacity. When the bearing capacity drops to 85% or 70% of the design value, early warnings can be triggered in a graded manner. Sudden changes in damage rate (such as a 200% increase) can also be combined to identify sudden risks, thus breaking through the limitations of traditional static assessment methods. This provides a dynamic assessment tool that combines theoretical rigor and engineering applicability for life prediction and maintenance decisions of steel pipe piles in marine environments, significantly improving the foresight and reliability of structural safety management.

[0157] See also Figure 6 The present invention further provides a device for calculating the bending bearing capacity of a steel pipe pile, wherein the device is used to implement the above-mentioned method for calculating the bending bearing capacity of a steel pipe pile, and comprises:

[0158] The potential damage area identification module is used to arrange a distributed optical fiber and a three-electrode system on the surface of the steel pipe pile. The distributed optical fiber monitors the Bragg wavelength to obtain the strain distribution, and uses the spatial gradient analysis method to analyze the strain distribution to identify potential damage areas.

[0159] The corrosion depth determination module is used to activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain of the potential damage area exceeds the threshold. If the threshold is exceeded, the corrosion current density is corrected by applying the corrosion acceleration factor. The corrosion current velocity is calculated based on the corrected corrosion current density to obtain the cumulative corrosion depth;

[0160] The multi-damage coupling assessment module is used to convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles at each strain amplitude in the potential damage area is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected, and a multi-damage coupling model is constructed by integrating the stress amplitude, chloride ion concentration and temperature difference variation amplitude data to obtain the corrosion damage degree.

[0161] The bearing capacity calculation and early warning module is used to analyze the impact of the service life of steel pipe piles on the yield strength to obtain the yield strength of the steel pipe piles at the current moment. Based on the yield strength, fatigue damage degree, corrosion damage degree and cumulative corrosion depth of the steel pipe piles at the current moment, the current bending bearing capacity is determined. The relationship between the current bending bearing capacity of the steel pipe piles and the design value of the bending bearing capacity is analyzed to determine the early warning mechanism.

[0162] The present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned method for calculating the bending bearing capacity of a steel pipe pile.

[0163] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0164] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0165] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0166] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A method for calculating the bending bearing capacity of a steel pipe pile, characterized in that: The specific steps include: Step 1: Distributed optical fiber and a three-electrode system are arranged on the surface of the steel pipe pile. The Bragg wavelength is monitored by the distributed optical fiber to obtain the strain distribution. The strain distribution is analyzed using the spatial gradient analysis method to identify potential damage areas. Step 2: Activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain in the potential damage area exceeds the threshold. If it exceeds the threshold, apply the corrosion acceleration factor to correct the corrosion current density. Calculate the corrosion current velocity based on the corrected corrosion current density to obtain the cumulative corrosion depth. Step 3: Convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles of the potential damage area at each strain amplitude is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected. The stress amplitude, chloride ion concentration and temperature difference variation amplitude data are integrated to construct a multi-damage coupling model to obtain the corrosion damage degree. Step 4: Analyze the effect of the service life of the steel pipe pile on the yield strength to obtain the yield strength of the steel pipe pile at the current moment. Based on the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, determine the bending bearing capacity at the current moment. Analyze the relationship between the bending bearing capacity of the steel pipe pile at the current moment and the design value of the bending bearing capacity to determine the early warning mechanism.

2. The method for calculating the bending bearing capacity of a steel pipe pile according to claim 1, wherein: Identifying the potential damage area specifically includes: The three-electrode system includes a working electrode, a counter electrode, and a reference electrode. An optical fiber sensor is arranged along the axial direction of the steel pipe pile to construct a uniaxial coordinate system. The Bragg wavelength is obtained by the optical fiber sensor, and the strain distribution is obtained by calculating the shift of the Bragg wavelength. The formula is as follows: ； in, is the strain of the steel pipe pile at the current moment, is the elastic-optical coefficient, is the initial Bragg wavelength, is the Bragg wavelength of the steel pipe pile at the current moment, x is the position coordinate variable of the steel pipe pile, Indicates the current moment; The spatial gradient analysis method is used to analyze the strain gradient at each position of the steel pipe pile. The formula is as follows: ； in, is the strain gradient of the steel pipe pile at position x at the current moment; The strain gradient at each position is judged. If , the location is classified as a potential damage area.

3. The method for calculating the bending bearing capacity of a steel pipe pile according to claim 1, characterized in that: Measuring the corrosion current density specifically includes: Activate the three-electrode system in the potential damage area, apply potential perturbation and measure the current response. Record the potential shift and current response to obtain the polarization resistance, which is calculated as follows: ； ； in, is the polarization resistance of the potential damage area at the current moment, d represents the position coordinate variable in the potential damage area, is the potential offset of the potential damage area d at the current moment, is the forward scanning potential of the potential damage area d at the current moment, is the negative scanning potential of the potential damage area d at the current moment, is the current response of the potential damage area d at the current moment, is the forward current response of the potential damage area d at the current moment, is the negative current response of position d in the potential damage area at the current moment; The formula for calculating corrosion current density is as follows: ； in, is the corrosion current density at the potential damage area d at the current moment, B is the Stern-Geary constant, is the polarization resistance of position d in the potential damage area at the current moment.

4. A method for calculating the bending bearing capacity of a steel pipe pile according to claim 3, characterized in that: Obtaining the cumulative corrosion depth specifically includes: Judge the strain of the potential damage area at the current moment. If , then the corrosion acceleration factor is not applied to the potential damage area d. , the corrosion current density is corrected using the corrosion acceleration factor, where is the strain at position d in the potential damage area at the current moment; The corrosion current density at the current moment is corrected by the corrosion acceleration factor to obtain the corrected corrosion current density at the current moment. The formula is as follows: ； in, is the corrosion current density at the corrected potential damage zone d at the current moment, is the corrosion acceleration factor; if ,but ,like ,but , Indicates the strain at the current moment; The corrosion rate formula is as follows: ； in, is the corrosion rate of the potential damage area d at the current moment, EW is the metal electrochemical equivalent, is the material density; The formula for calculating the cumulative corrosion depth is as follows: ； in, is the cumulative corrosion depth of the potential damage area d at the current moment, Indicates the potential damage area d is located at The corrosion rate at the time, Represents the time variable from the initial moment to the current moment, is the corrosion depth of the potential damage area d at the initial time, and the initial time is the starting time for the assessment of the bearing capacity of the steel pipe pile.

5. A method for calculating the bending bearing capacity of a steel pipe pile according to claim 4, characterized in that: Calculating the fatigue damage degree specifically includes: The strain time series data of the potential damage area from the initial moment to the current moment are obtained. The strain time series data are processed based on the rain flow counting method to generate a strain amplitude sequence. Specifically, the strain time series data are arranged in time sequence to determine multiple maxima and minima. Starting from the first maximum value, the difference between the maximum value and the adjacent minimum value is used as the first strain amplitude. The number of cycles is recorded and all the maxima are traversed in turn to obtain the strain amplitude sequence, which is expressed as: ; in, is the y-th strain amplitude in the strain amplitude sequence, y represents the index of the strain amplitude, represents the actual number of cycles corresponding to the y-th strain amplitude, Y is the total number of strain amplitude types, and y∈[1,Y]; Set k amplitude levels and determine the strain amplitude range corresponding to each amplitude level. For each strain amplitude, classify it into the corresponding amplitude level according to its numerical value, and accumulate the actual number of cycles corresponding to the strain amplitude to the total number of actual cycles of the amplitude level to which it belongs. Then, filter out the high strain amplitude level that causes fatigue damage to steel pipe piles from all amplitude levels. Calculate the fatigue damage degree of the potential damage area at the current moment using the following formula: ； in, Indicates the potential damage area d position and the fatigue damage degree at the current moment, It represents the total number of actual cycles in amplitude level j from the initial moment to the current moment at the potential damage area d, where j represents the amplitude level. represents the minimum value of the set high strain amplitude level, k is the total number of amplitude levels, and , the larger the j value is, the larger the corresponding amplitude level is. ,k] range belongs to the high strain amplitude level, is the design life of the steel pipe pile, Indicates the length of time from the initial moment to the current moment. is the total number of fatigue cycles allowed in the design.

6. A method for calculating the bending bearing capacity of a steel pipe pile according to claim 5, characterized in that: Constructing the multi-damage coupling model specifically includes: The strain amplitude at each location in the potential damage area is converted into stress amplitude using the following formula: ； in, is the stress amplitude at the potential damage area d at the current moment, is the elastic modulus of the material, is the strain amplitude at the potential damage area d at the current moment, that is, the maximum strain amplitude in the strain amplitude sequence; The crack depth of the potential damage area at the current moment is measured by an eddy current detector. Combined with the stress amplitude, chloride ion concentration, and temperature change amplitude data, a multi-damage coupling model is constructed. The expression is as follows: ； ； in, Indicates the corrosion damage degree of the potential damage area d at the current moment, is the stress intensity factor amplitude at the potential damage zone d at the current moment, which is used to quantify the stress concentration degree at the crack tip of the external load on the steel pipe pile. is the chloride ion concentration at the potential damage area d at the current moment, is the temperature variation amplitude at the location of the steel pipe pile, that is, the difference between the maximum and minimum temperatures within 24 hours before the current moment. is the fatigue crack growth coefficient, is the corrosion sensitivity coefficient, C is the chloride ion influence index, is the temperature change damage coefficient, m is the fatigue crack growth index, is the geometric correction factor, a is the crack depth at position d in the potential damage area at the current moment.

7. The method for calculating the bending bearing capacity of a steel pipe pile according to claim 1, characterized in that: Obtaining the bending bearing capacity at the current moment specifically includes: According to the service life of the steel pipe pile and the benchmark life, the yield strength of the steel pipe pile at the current moment is obtained. The calculation formula is as follows: ； in, is the yield strength at the current moment, is the standard yield strength, For the duration of use, is the baseline lifespan, is the degradation rate coefficient; According to the yield strength, fatigue damage, corrosion damage and cumulative corrosion depth of the steel pipe pile at the current moment, the bending bearing capacity of the steel pipe pile at the current moment is obtained. The calculation formula is as follows: ； in, is the bending bearing capacity of the potential damage zone d at the current moment, is the initial bending bearing capacity of the steel pipe pile, is the fatigue damage degree of the potential damage area d at the current moment, is the corrosion damage degree of the potential damage area d at the current moment, is the fatigue-corrosion interaction factor, is the cumulative corrosion depth of the potential damage area d at the current moment, is the outer diameter of the steel pipe pile; The bending bearing capacity of all positions in the potential damage zone of the steel pipe pile is traversed, and the minimum value of the bending bearing capacity of all positions in the potential damage zone is taken as the bending bearing capacity of the steel pipe pile at the current moment. The bending bearing capacity of the steel pipe pile at the current moment is compared with the design value. If the bending bearing capacity drops to 85% of the design value, a yellow warning is issued. If the bending bearing capacity drops to 70% of the design value, a red warning is issued. The damage rate is monitored. If the damage rate increases by 200% compared with the previous moment, an emergency warning is issued.

8. A device for calculating the bending bearing capacity of steel pipe piles, characterized in that: The device for calculating the bending bearing capacity of a steel pipe pile is used to implement the method for calculating the bending bearing capacity of a steel pipe pile according to any one of claims 1 to 7, comprising: The potential damage area identification module is used to arrange a distributed optical fiber and a three-electrode system on the surface of the steel pipe pile. The distributed optical fiber monitors the Bragg wavelength to obtain the strain distribution, and uses the spatial gradient analysis method to analyze the strain distribution to identify potential damage areas. The corrosion depth determination module is used to activate the three-electrode system in the potential damage area, measure the corrosion current density by the polarization resistance method, and determine whether the strain of the potential damage area exceeds the threshold. If the threshold is exceeded, the corrosion current density is corrected by applying the corrosion acceleration factor. The corrosion current velocity is calculated based on the corrected corrosion current density to obtain the cumulative corrosion depth; The multi-damage coupling assessment module is used to convert the strain distribution of the potential damage area into a strain amplitude sequence. The actual number of cycles at each strain amplitude in the potential damage area is obtained through the strain amplitude sequence to determine the fatigue damage degree of the potential damage area. The chloride ion concentration and temperature difference variation amplitude of the potential damage area are collected, and a multi-damage coupling model is constructed by integrating the stress amplitude, chloride ion concentration and temperature difference variation amplitude data to obtain the corrosion damage degree. The bearing capacity calculation and early warning module is used to analyze the impact of the service life of steel pipe piles on the yield strength to obtain the yield strength of the steel pipe piles at the current moment. Based on the yield strength, fatigue damage degree, corrosion damage degree and cumulative corrosion depth of the steel pipe piles at the current moment, the current bending bearing capacity is determined. The relationship between the current bending bearing capacity of the steel pipe piles and the design value of the bending bearing capacity is analyzed to determine the early warning mechanism.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for calculating the bending bearing capacity of a steel pipe pile according to any one of claims 1 to 7 is implemented.

Images