Method and system for estimating vertical bearing capacity of steel pipe pile

Abstract

The invention provides a method and system for estimating the vertical bearing capacity of a steel pipe pile, and relates to the technical field of pile foundation engineering.The method comprises the steps that a static cone penetration test is conducted on a seabed stratum needing to be arranged for a steel pipe pile foundation, experimental data are obtained and subjected to normalization processing, soil behavior types are divided, and soil layer mechanical parameters are inverted; calculating side friction resistance and end resistance of the steel pipe pile based on the soil layer mechanical parameters to obtain initial static ultimate bearing capacity; historical equivalent cyclic load experimental data of waves in the construction sea area are obtained, an equivalent cyclic load reduction coefficient, a liquefaction reduction coefficient and a time-varying corrosion reduction coefficient are constructed, and a comprehensive time-varying reduction coefficient is constructed; the initial static ultimate bearing capacity is corrected based on the comprehensive time-varying reduction coefficient, the vertical bearing capacity of the steel pipe pile in the long-term service period is predicted, and the time-varying ultimate bearing capacity is obtained; setting an evaluation threshold according to the time-varying ultimate bearing capacity, dynamically adjusting a bearing capacity grading threshold interval, and outputting a bearing capacity grading evaluation result.

Description

Technical Field

[0001] This invention relates to the field of pile foundation engineering technology, specifically to a method and system for estimating the vertical bearing capacity of steel pipe piles. Background Technology

[0002] With the rapid development of offshore wind power, offshore oil platforms, and other marine engineering projects, steel pipe piles, as a crucial foundation type for marine engineering structures, require accurate estimation of their bearing capacity for engineering safety. Steel pipe piles serve in the marine environment for extended periods, and their bearing performance is influenced by various factors, including soil properties, environmental loads, and material properties. Currently, methods for estimating the vertical bearing capacity of steel pipe piles mainly rely on static cone penetration test data, high-strain test data, and empirical formulas.

[0003] Static cone penetration testing (CPPT) is an important method for obtaining geological parameters. Existing technology, publication number CN102587426A, discloses an analytical method for estimating pile foundation bearing capacity based on CPPT. This method measures the cone tip resistance and side skin friction corresponding to different relative deformations between the probe and the soil, extracts the pile end resistance and pile side skin friction corresponding to different pile-soil relative deformations for various soil types, establishes empirical formulas, and inversely calculates the pile foundation load-settlement curve to determine the pile foundation bearing capacity. This method has a clear mechanism and is simple to apply, but it mainly targets land-based pile foundations and does not consider the special characteristics of marine environments.

[0004] In the field of offshore wind power, the existing technology with publication number CN119203746A proposes a method for predicting the bearing capacity of a single pile in offshore wind power. This method is based on pore pressure static cone penetration tests to obtain measured data of the single pile in different strata, determines the side skin resistance and unit pile end resistance in different strata, and combines a neural network model and a genetic algorithm for optimization prediction. This method improves the prediction accuracy, but does not fully consider the impact of time-varying factors in the marine environment on the long-term bearing capacity of the pile foundation.

[0005] For the analysis of the vertical bearing capacity of pipe piles, CN108509755A discloses a method and system for analyzing the vertical bearing capacity of pipe piles based on high-strain test data. This method acquires massive amounts of high-strain test data, extracts mechanical parameters to construct a basic database, uses big data analysis technology to classify, statistically analyze, and calculate the mechanical parameters, and combines this with finite element analysis to construct a load transfer function, ultimately determining the ultimate bearing capacity of the pipe pile. While this method considers the influence of different soil types on bearing capacity, it does not systematically study the cyclic loading effect in marine environments.

[0006] However, existing methods for estimating the bearing capacity of steel pipe piles have the following shortcomings: First, most methods are based primarily on static soil mechanics parameters, failing to adequately consider dynamic factors in the marine environment; second, they do not adequately account for time-varying factors such as cyclic loading effects, soil liquefaction, and steel corrosion in the marine environment; third, they lack a systematic approach that couples multiple influencing factors for analysis; and finally, existing methods struggle to accurately predict the changes in the bearing capacity of steel pipe piles during long-term service, thus failing to provide a reliable basis for engineering safety assessments. Especially in deep-sea or complex seabed conditions, traditional methods cannot accurately reflect the actual working state of the pile foundation, leading to significant uncertainties in engineering design and impacting the safety and economy of marine engineering structures.

[0007] Therefore, there is an urgent need to develop a method for estimating the vertical bearing capacity of steel pipe piles that can comprehensively consider the time-varying effects of multiple mechanisms coupled together, such as cyclic loads, soil liquefaction, and material corrosion in the marine environment, in order to improve the accuracy and reliability of marine engineering pile foundation design.

[0008] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide a method and system for estimating the vertical bearing capacity of steel pipe piles, so as to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: The method for estimating the vertical bearing capacity of steel pipe piles includes the following steps: S1: Conduct static cone penetration tests on the seabed strata required for steel pipe pile foundations, obtain experimental data at each depth test point in the static cone penetration test, normalize the experimental data point by point, classify soil behavior types based on the normalization results, and invert the mechanical parameters of soil layers of each soil behavior type. S2: Based on the soil mechanical parameters of each soil behavior type, calculate the side friction between the steel pipe pile body and the surrounding soil and the end resistance at the pile end to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions. S3: Obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction coefficient, liquefaction reduction coefficient and time-varying corrosion reduction coefficient, and construct comprehensive time-varying reduction coefficient through multi-mechanism coupling. S4: Based on the comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, the vertical bearing capacity of the steel pipe pile during the long-term service period is predicted, and the time-varying ultimate bearing capacity of the steel pipe pile is obtained. S5: Set the bearing capacity assessment threshold according to the time-varying ultimate bearing capacity, and dynamically adjust the bearing capacity grading threshold range. Match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output the grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile.

[0011] Furthermore, during the static cone penetration test, the seabed strata region was selected based on the location of the steel pipe pile foundation. During the test, a static cone penetration device was used to advance the device through the seabed strata in layers, with a predetermined total detection depth and equal intervals between detection layers. The midpoint depth of each predetermined equal interval layer was used as a test point to collect experimental data. The experimental data included: net cone tip resistance, side friction resistance, and static pore water pressure at each test point. The experimental data were normalized point by point to obtain the normalized cone tip resistance and normalized friction ratio for each test point, forming a data sequence for different test points. The specific formulas for obtaining the normalized cone tip resistance and normalized friction ratio for each test point are as follows: ; in, For the first Depth of each test point for Normalized cone tip resistance at depth for Normalized friction ratio at depth for Net cone tip resistance at depth for Side friction at depth Standard atmospheric pressure for Total overburden stress at depth for Effective overburden stress, Stress index; Total overburden stress, i.e., current depth The total weight of all the soil, including seawater, is calculated using the following formula: ; ; in, The density of seawater, It is the acceleration due to gravity. Because of the water depth, The soil weight, yes Static pore water pressure at depth; further, soil layers are divided based on the normalized results, i.e., according to... and Soil behavior was classified by comparing with the soil behavior type chart, and the soil behavior types were divided into clay, sand, and mixed soil. The soil behavior type corresponding to the test point at the midpoint depth of each predetermined detection interval layer represents the soil behavior type of that detection interval layer. At the same time, the mechanical parameters of each interval layer were inverted for each interval layer soil behavior type. The undrained shear strength was inverted for clay interval layer, and the internal friction angle was inverted for sand interval layer. The inversion formulas are as follows: ; ; in, clay-based interlayer Undrained shear strength at depth For the empirical cone factor, Sandy soil interlayer The internal friction angle at depth; the equivalent friction angle and equivalent cohesion of the mixed soil interlayer are solved iteratively, satisfying the following formula: ; in, Interlayer of mixed soil Equivalent internal friction angle at depth This is a soil behavior index. This is an empirical coefficient. Interlayer of mixed soil Equivalent cohesion at depth.

[0012] Furthermore, the side friction between the steel pipe pile and the surrounding soil, and the end resistance at the pile tip are calculated. The steel pipe pile is divided along the depth direction from the soil surface to the pile tip into... Each micro-segment is at the same height as the probe's equally spaced layers, with the midpoint depth of each micro-segment being equal to... One-to-one correspondence, the height of each micro-segment is The initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions is obtained: ; in, This is the initial ultimate bearing capacity. for Side friction at the micro-segment For end resistance, For micro-segment numbers, The underwater weight of the steel pipe pile.

[0013] Furthermore, each micro-segment of the steel pipe pile is located in an interval layer with different soil behavior types. The side skin friction corresponding to the interval layer with different soil behavior types for each micro-segment is calculated separately, and the end resistance corresponding to the different soil behavior types of the steel pipe pile tip is also calculated. When the soil behavior type of the micro-segment is clay, the formulas for the side skin friction and end resistance are as follows: ; When the soil behavior type of the micro-segment is a sandy interlayer, the formulas for side friction and end resistance are as follows: ; When the soil behavior type of the micro-segment is a mixed soil interlayer, the formulas for side friction and end resistance are as follows: ; in, micro-segment The adhesion coefficient at the location, The lateral earth pressure coefficient, The diameter of the steel pipe pile is... The bearing capacity coefficient related to the friction angle of the sandy soil interlayer is... The bearing capacity coefficient related to the friction angle of the mixed soil interlayer is... This refers to the bearing capacity coefficient related to the cohesion of clay-based interlayers. This is the bearing capacity coefficient related to the cohesion of the interlayer in mixed soil.

[0014] Furthermore, equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed were obtained. Equivalent cyclic load reduction factors, liquefaction reduction factors, and time-varying corrosion reduction factors were constructed. A comprehensive time-varying reduction factor was then constructed through multi-mechanism coupling. The formula is as follows: ; in, To incorporate the time-varying reduction factor, This is the liquefaction reduction factor. The construction approach for the time-varying corrosion reduction factor, liquefaction reduction factor, and time-varying corrosion reduction factor is as follows: Historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed are obtained. This historical equivalent cyclic load experimental data includes: the annual average number of equivalent cyclic loads in the construction sea area, the annual average equivalent cyclic load stress ratio, the annual average equivalent cyclic load resistance ratio, and the equivalent cyclic load reduction factor. The calculation formulas for the liquefaction reduction factor and the time-varying corrosion reduction factor are as follows: ; in, This is the equivalent cyclic load reduction factor. For cyclic load empirical coefficients, The average equivalent number of cycles, This is the empirical coefficient for liquefaction reduction. The annual average equivalent cyclic load stress ratio, The annual average equivalent cyclic load resistance ratio. for and The ratio of the average values, This represents the initial wall thickness of the steel pipe pile. The length of the steel pipe pile. For corrosion depth, It is a time variable.

[0015] Furthermore, based on the comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, and the vertical bearing capacity of the steel pipe pile during its long-term service period is predicted, thus obtaining the time-varying ultimate bearing capacity of the steel pipe pile, as shown in the following formula: ; in, This is the initial ultimate bearing capacity. The time-varying ultimate bearing capacity, i.e. Limit load capacity at all times.

[0016] Furthermore, based on the time-varying ultimate bearing capacity, a bearing capacity assessment threshold is set, and the bearing capacity grading threshold range is dynamically adjusted. The time-varying ultimate bearing capacity is matched with the dynamic bearing capacity grading threshold range, and a grading evaluation result for the vertical bearing capacity to be estimated of the steel pipe pile is output. The specific logic is as follows: If Therefore, it is safe and has sufficient load-bearing capacity; like If so, it's normal; the steel pipe pile is in a normal state. If the load-bearing capacity is below or close to the failure threshold, an early warning will be issued; where, This is the preset load-bearing capacity threshold.

[0017] The present invention also provides a system for estimating the vertical bearing capacity of steel pipe piles, the system being used to execute the above-described method for estimating the vertical bearing capacity of steel pipe piles, comprising: The exploration and data processing module is used to conduct static cone penetration tests on the seabed strata required for steel pipe pile foundations, obtain experimental data at each depth test point in the static cone penetration test, normalize the experimental data point by point, classify soil behavior types based on the normalization results, and invert the mechanical parameters of soil layers of each soil behavior type. Static bearing capacity calculation module: used to calculate the side friction resistance between the steel pipe pile body and the surrounding soil and the end resistance of the pile end based on the soil mechanical parameters of each soil behavior type, so as to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions. Time-varying reduction factor calculation module: used to obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction factor, liquefaction reduction factor and time-varying corrosion reduction factor, and construct comprehensive time-varying reduction factor through multi-mechanism coupling; Time-varying bearing capacity prediction module: used to correct the initial static ultimate bearing capacity of steel pipe piles based on the comprehensive time-varying reduction coefficient, predict the vertical bearing capacity of steel pipe piles during long-term service, and obtain the time-varying ultimate bearing capacity of steel pipe piles; Safety level assessment module: used to set the bearing capacity assessment threshold based on the time-varying ultimate bearing capacity, dynamically adjust the bearing capacity grading threshold range, match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output the grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: By obtaining soil layer parameters through static cone penetration tests and performing normalization processing, accurate classification of different soil behavior types and inversion of mechanical parameters are achieved. Compared with traditional methods, this method more accurately reflects the actual situation of seabed strata and improves the accuracy of basic data for bearing capacity estimation. The steel pipe pile is divided into multiple micro-segments along the depth direction, and the side friction and end resistance under different soil layer types are calculated separately and accumulated to obtain the initial ultimate bearing capacity. This micro-element method reflects the complexity of pile-soil interaction better than traditional overall calculation methods, improving the accuracy of static bearing capacity calculation. Furthermore, a comprehensive time-varying reduction coefficient is innovatively constructed. By coupling multiple time-varying factors such as cyclic loading, soil liquefaction, and material corrosion, this invention achieves full-cycle safety assessment from static to dynamic and from short-term to long-term perspectives, overcoming the shortcomings of traditional methods that only consider static conditions. By setting dynamic threshold ranges and matching time-varying bearing capacity with thresholds, it outputs safe, normal, or warning levels, realizing dynamic assessment of the bearing capacity state of steel pipe piles. This can be flexibly adjusted according to different engineering safety standards, improving the practicality and adaptability of the assessment results. Compared with existing technologies, the method of this invention improves the accuracy of steel pipe pile bearing capacity prediction in marine environments, providing more reliable technical support for the long-term safety assessment of marine engineering structures. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a graph showing the variation of static cone penetration test parameters with depth according to an embodiment of the present invention; Figure 3This is a graph showing the relationship between corrosion depth and reduction factor in some embodiments of the present invention; Figure 4 This is a schematic block diagram of the vertical bearing capacity estimation system for steel pipe piles in this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] Example: Please see Figures 1 to 3 The present invention provides a technical solution: The method for estimating the vertical bearing capacity of steel pipe piles includes the following steps: S1: A static cone penetration test is conducted on the seabed strata required for the steel pipe pile foundation. Experimental data at each depth test point is obtained. The experimental data is normalized point by point. Based on the normalization results, soil behavior types are classified, and the mechanical parameters of each soil behavior type are obtained through inversion. In this embodiment, during the static cone penetration test, the seabed strata region is selected according to the location of the steel pipe pile foundation. During the static cone penetration test, a static cone penetration device is used to advance the seabed strata layer by layer, with a predetermined total detection depth and equal intervals between detection layers. At the midpoint depth of each predetermined equally spaced layer, experimental data were collected. The experimental data included net cone tip resistance, side friction resistance, and static pore water pressure at each test point. The experimental data were normalized point-by-point to obtain the normalized cone tip resistance and normalized friction ratio for each test point, forming a data sequence for different test points (see Table 1). Normalization was used to eliminate the influence of overlying stress on the test results, allowing static cone penetration test data from different depths and geological conditions to be compared and classified under the same standard. For each depth point... The stress conditions are calculated separately using normalization; the specific formulas for obtaining the normalized cone tip resistance and normalized friction ratio for each test point are as follows: ; in, For the first Depth of each test point for Normalized cone tip drag at depth is used to eliminate effective overburden stress at different depths. The influence of this necessitates normalization of the net cone tip resistance. A stress exponent is used here. We need to consider the effect of stress level on the normalization effect. A commonly used normalization method is to divide the net cone tip drag by standard atmospheric pressure. Then multiply by the ratio of effective overburden stress to reference stress. The purpose of this is to convert the cone tip drag at different stress levels to standard atmospheric pressure. The comparison is made because soil stiffness varies under different confining pressures. This is a stress level correction term; for Normalized friction ratio at depth, the friction ratio is the sidewall frictional resistance. With cone tip resistance The ratio of [the two values], however, to more accurately reflect the properties of the soil, the net cone tip resistance is used here. As the denominator, the sidewall friction resistance It mainly reflects the frictional characteristics of the pile-soil interface, while the cone tip resistance... Subtracting the overburden stress provides a more accurate reflection of the soil's true strength. Therefore, using... Dividing by the net cone tip resistance can eliminate the influence of overburden stress on the friction ratio, making the friction ratio more reflective of the soil type; for Net cone tip resistance at depth for Side friction at depth Standard atmospheric pressure for Total overburden stress at depth for Effective overburden stress at depth Stress index; Total overburden stress, i.e., current depth The total weight of all the soil, including seawater, is calculated using the following formula: ; ; in, The density of seawater, It is the acceleration due to gravity. Because of the water depth, The soil weight, yes Static pore water pressure at depth; soil layers are divided based on normalized results, i.e., according to... and Soil behavior was classified by comparing with the soil behavior type chart, and the soil behavior types were divided into clay, sand, and mixed soil. The soil behavior type corresponding to the test point at the midpoint depth of each predetermined detection interval layer represents the soil behavior type of that detection interval layer. At the same time, the mechanical parameters of each interval layer were inverted for each interval layer soil behavior type. The undrained shear strength was inverted for clay interval layer, and the internal friction angle was inverted for sand interval layer. The inversion formulas are as follows: ; ; in, clay-based interlayer The undrained shear strength at depth is determined based on the spherical cavity expansion theory, establishing a relationship between the net cone tip resistance and the undrained shear strength. For the empirical cone factor, Sandy soil interlayer The internal friction angle at depth; the equivalent friction angle and equivalent cohesion of the mixed soil interlayer are solved iteratively, satisfying the following formula: ; in, Interlayer of mixed soil Equivalent internal friction angle at depth This is a soil behavior index. This is an empirical coefficient. Interlayer of mixed soil Equivalent cohesion at depth.

[0023] Static cone penetration testing significantly reduces soil sample disturbance and stress release errors associated with traditional borehole sampling and laboratory testing. Soil parameter inversion is based on internationally recognized soil classification charts (such as the Robertson diagram) and inversion formulas, transforming the probe data into the mechanical parameters directly required for design. In this embodiment, the marine static cone penetration test system is positioned at the designed location of the pile foundation. The probe is driven into the seabed at a constant rate of 2 cm / s until the predetermined depth is reached. Sensors continuously collect net cone tip resistance, side friction resistance, and pore water pressure at each depth point. Normalization and a systematic soil behavior classification (Robertson chart) are employed to calculate the total overburden stress and effective overburden stress point by point based on soil and seawater information. The steel pipe pile parameters are: diameter 1.5m, length 50m, initial wall thickness 0.05m, and underwater self-weight 600kN. The required seawater area for the steel pipe pile foundation has a density of 1025 kg / m³, a depth of 21.7 m, a gravitational acceleration of 9.81 m / s², and a standard atmospheric pressure of 101.3 kPa. Normally consolidated clay is very sensitive to confining pressure, and its stiffness is roughly proportional to the effective stress; therefore, the stress index for clay is 1. The stiffness of quartz sand is roughly proportional to the square root of the effective stress; therefore, the stress index for sand is 0.5. The properties of mixed soil are between the two, so a middle value is taken; therefore, the stress index for mixed soil is 0.75. (Empirical cone factor...) The cone-shaped values ​​need to be calibrated based on regional experience and should be referenced from local geological survey reports and engineering experience; experience coefficients empirical coefficient Soil Behavior Index In this embodiment, the data obtained through step S1 is... for Net cone tip resistance at depth for The side friction resistance at depth was calculated, and the experimental data is shown in Table 1 below. Table 1 clearly shows the data from each test point at a depth of 50 meters from the seabed surface. The table contains the original experimental data for each depth point. , , and the calculated key normalization parameters , And inversion parameters.

[0024] Table 1: Soil Behavior Data at Test Points

[0025] Please see Figure 2 , Figure 2This embodiment clearly demonstrates that in step S1, a static cone penetration test (CPPT) is used to advance the seabed strata in layers. The predetermined total detection depth and the intervals between detection layers are defined. The total detection depth should ensure complete coverage of the pile foundation's influence zone and must be greater than the pile's penetration depth, while also considering the significant impact of the soil below the pile tip on bearing capacity. The goal is to reveal all soil layers within the range of pile friction resistance, as well as the bearing layer and underlying layers upon which the pile end resistance depends. The predetermined total depth should be at least the planned penetration depth plus k times the pile diameter, as the soil properties within the k times pile diameter range significantly affect end resistance. The predetermined interval height is also defined; smaller intervals result in higher data density and stronger resolution of thin interlayers, but also longer exploration time and larger data volume. Excessively large intervals may miss crucial thin layers, leading to model distortion. In this embodiment, 2m is used as the CPPT interval height, and the midpoint depth of each predetermined CPPT interval is used as a test point. The collected experimental data include net cone tip resistance, side friction resistance, and static pore water pressure at each test point, which are visualized in Table 1. Figure 2 We can see the net cone tip resistance. A clear stratification trend emerges with increasing depth: in the shallow layer, approximately 1–9 meters in the clay layer, The value is low and the growth is slow; after entering the sandy layer, at approximately 11–33 meters, The bearing capacity of sandy soil increases significantly, exhibiting its high bearing capacity characteristics; in deeper mixed soil layers, at depths of 35–49 meters, The value tends to stabilize. Side friction resistance. It also gradually increases with depth, especially in sandy and mixed soil layers where the increase is more significant. Static pore water pressure The coefficient of variation increases linearly with depth, consistent with the distribution law of hydrostatic pressure. These trends provide a reliable data basis for the classification of soil behavior types and the inversion of mechanical parameters.

[0026] S2: Based on the soil mechanical parameters of each soil behavior type, calculate the side friction resistance between the steel pipe pile and the surrounding soil and the end resistance at the pile tip to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions; calculate the side friction resistance between the steel pipe pile and the surrounding soil and the end resistance at the pile tip, and divide the steel pipe pile from the soil surface to the pile tip along the depth direction into... Each micro-segment is at the same height as the probe's equally spaced layers, with the midpoint depth of each micro-segment being equal to... One-to-one correspondence, meaning the height of the micro-segment matches the height of the equally spaced detection layer. Micro-segment correspondence The probe spacer layer, the corresponding height of each micro-segment is The initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions is obtained: ; in, This is the initial ultimate bearing capacity. for Side friction at the micro-segment For end resistance, For micro-segment numbers, The underwater self-weight of the steel pipe pile is considered. Each micro-segment of the steel pipe pile is located in an interval layer with different soil behavior types. The side skin friction corresponding to the soil behavior type interval layer of each micro-segment is calculated separately, and the end resistance corresponding to different soil behavior type interval layers at the pile tip is also calculated. When the soil behavior type of the micro-segment is clay, the formulas used for the side skin friction and end resistance are as follows: ; When the soil behavior type of the micro-segment is a sandy interlayer, the formulas for side friction and end resistance are as follows: ; Based on the effective stress principle, it is assumed that the side friction resistance is proportional to the effective overburden stress at that point; if Taking a value that is too small will underestimate the side skin resistance in sandy soil; the pile driving process has an impact on... The value has a significant impact; if Taking a value that is too large will directly overestimate the side friction resistance.

[0027] When the soil behavior type of the micro-segment is a mixed soil interlayer, the formulas for side friction and end resistance are as follows: ; in, micro-segment The adhesion coefficient at the location, The lateral earth pressure coefficient, The diameter of the steel pipe pile is... The bearing capacity coefficient related to the friction angle of the sandy soil interlayer is... The bearing capacity coefficient related to the friction angle of the mixed soil interlayer. This refers to the bearing capacity coefficient related to the cohesion of clay-based interlayers. It provides bearing capacity coefficients related to cohesion in mixed soil layers; and offers different calculation models for clay, sand, and mixed soil, enabling flexible adaptation to complex marine geological conditions. , The value of the bearing capacity coefficient directly affects the end resistance. By adopting the layered summation method, the contribution of different soil layers to the lateral resistance is refined, the source of the end resistance is clarified, and the physical meaning of the model is clear, which is far superior to a single comprehensive formula. In this embodiment, based on the experimental results of S1 and the required data, the initial ultimate bearing capacity is further calculated, wherein, ; The actual adhesion force at the pile-soil interface in clay is not equal to the undrained shear strength of the soil; the adhesion coefficient is used to represent this reduction. The value is related to the soil's sensitivity and stress history; the complex interaction between the pile and soil interfaces is simplified into an empirical coefficient related to soil strength and stress history. For clay with high overconsolidation ratio and high strength, The value is relatively small; for normally consolidated soft clay, The value is relatively large, but does not exceed 1.0.

[0028] ; ; In this embodiment, , Lateral earth pressure coefficient 0.8. The piling process will severely disturb the soil. For open piles, some soil core will enter the pile tube, and the squeezing effect on the surrounding soil is less than that of closed piles. Therefore... The value is less than the coefficient of earth pressure at rest, which is usually approximately equal to... ; In this embodiment, the second micro-segment is selected. The side friction resistance is calculated at the 25th micro-segment. End resistance, as a calculation example: ; Summing over all 25 micro-segments, , This calculation is for illustrative purposes and is intended to demonstrate the process. In actual calculations, all micro-segments need to be summed precisely, and the formula for pile end resistance may differ. Here, the S2 formula is used for calculation, and subsequent time-varying reductions will be based on this new value.

[0029] S3: Obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction coefficient, liquefaction reduction coefficient and time-varying corrosion reduction coefficient, and construct comprehensive time-varying reduction coefficient through multi-mechanism coupling. In this embodiment, equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed are obtained. Equivalent cyclic load reduction coefficients, liquefaction reduction coefficients, and time-varying corrosion reduction coefficients are constructed. A comprehensive time-varying reduction coefficient is then built through multi-mechanism coupling. The formula is as follows: ; in, To incorporate the time-varying reduction factor, This is the liquefaction reduction factor. The construction approach for the time-varying corrosion reduction factor, liquefaction reduction factor, and time-varying corrosion reduction factor is as follows: Historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed are obtained. This historical equivalent cyclic load experimental data includes: the annual average number of equivalent cyclic loads in the construction sea area, the annual average equivalent cyclic load stress ratio, the annual average equivalent cyclic load resistance ratio, and the equivalent cyclic load reduction factor. The calculation formulas for the liquefaction reduction factor and the time-varying corrosion reduction factor are as follows: ; in, This is the equivalent cyclic load reduction factor. For cyclic load empirical coefficients, The average equivalent number of cyclic loads is used; a logarithmic fatigue cumulative damage model is adopted, which shows that the rate of bearing capacity degradation is fast at first and then slows down, which is consistent with the law of material fatigue test. This is the empirical coefficient for liquefaction reduction. The annual average equivalent cyclic load stress ratio, Two failure modes were captured for the annual average equivalent cyclic load resistance ratio: cyclic softening. and complete liquefaction , for and The ratio of their average values ​​is the core of judging liquefaction; if... The estimate is too high or Smaller test values ​​will lead to An increase in this factor may trigger a liquefaction reduction term, causing a sharp drop in load-bearing capacity. Calculating the ratio of remaining effective cross-sectional area directly from a geometric perspective is conceptually clear and has explicit physical meaning. This represents the initial wall thickness of the steel pipe pile. The length of the steel pipe pile. For corrosion depth, This is a time variable. In this embodiment, , .

[0030] S4: Based on the comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, and the vertical bearing capacity of the steel pipe pile during its long-term service period is predicted to obtain the time-varying ultimate bearing capacity of the steel pipe pile; based on the comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, and the vertical bearing capacity of the steel pipe pile during its long-term service period is predicted to obtain the time-varying ultimate bearing capacity of the steel pipe pile, as shown in the following formula: ; in, This is the initial ultimate bearing capacity. The time-varying ultimate bearing capacity, i.e. The ultimate bearing capacity at any given moment; the effects of the three reduction mechanisms on the bearing capacity are coupled and proportional to the initial bearing capacity; S5: Based on the time-varying ultimate bearing capacity, set a bearing capacity assessment threshold and dynamically adjust the bearing capacity grading threshold range. Match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output a grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile. The specific logic is as follows: If... Therefore, it is safe and has sufficient load-bearing capacity; like If so, it's normal; the steel pipe pile is in a normal state. If the load-bearing capacity is below or close to the failure threshold, an early warning will be issued; where, This is a preset bearing capacity threshold. In this embodiment, ,but, Then it is safe; Then it's normal. If an error occurs, a warning is issued. In this embodiment, the equivalent cyclic load reduction factor, liquefaction reduction factor, time-varying corrosion reduction factor, and time-varying ultimate bearing capacity data of the steel pipe pile are calculated using formulas based on the experimental data from steps S1 to S3, as shown in the table below: Table 2: Reduction Factor and Time-Varying Ultimate Bearing Capacity Data

[0031] As can be seen from Table 2, the corrosion depth increases over time. The time-varying corrosion reduction coefficient gradually increases. Corresponding reduction; equivalent cyclic load reduction factor and liquefaction reduction factor Influenced by the interannual fluctuations of wave loads, it exhibits a certain degree of volatility. (Comprehensive reduction factor) The variation between 0.664 and 0.82 results in a time-varying ultimate bearing capacity. The load fluctuated between 21288 kN and 26289 kN. At 20 years, due to significant liquefaction reduction, the bearing capacity dropped to the "normal" level, while in other years it remained in a "safe" state, indicating that the steel pipe piles in this embodiment have sufficient overall safety margin during their 30-year service life.

[0032] Please see Figure 3 , Figure 3 The paper clearly demonstrates the relationship between corrosion depth and the time-varying corrosion reduction coefficient and the comprehensive reduction coefficient during the service life of steel pipe piles. Corrosion depth is inversely proportional to both the time-varying corrosion reduction coefficient and the comprehensive reduction coefficient; the deeper the corrosion, the lower the reduction coefficient. Figure 3 It can be seen that the corrosion depth With reduction factor and A clear negative correlation is observed. As corrosion deepens, the effective cross-sectional area of ​​the pile decreases, leading to a gradual decline in the reduction factor. The curves in the figure clearly demonstrate the cumulative weakening effect of corrosion on long-term bearing capacity. They also reflect that under well-controlled corrosion conditions, the reduction factor decreases relatively slowly, but the reduction effect intensifies later as corrosion accelerates. This relationship highlights the importance of corrosion prevention measures in maintaining the long-term performance of pile foundations in marine environments.

[0033] Please see Figure 4 The present invention also provides a system for estimating the vertical bearing capacity of steel pipe piles, the system being used to execute the above-described method for estimating the vertical bearing capacity of steel pipe piles, comprising: The exploration and data processing module is used to conduct static cone penetration tests on the seabed strata required for steel pipe pile foundations, obtain experimental data at each depth test point in the static cone penetration test, normalize the experimental data point by point, classify soil behavior types based on the normalization results, and invert the mechanical parameters of soil layers of each soil behavior type. Static bearing capacity calculation module: used to calculate the side friction resistance between the steel pipe pile body and the surrounding soil and the end resistance of the pile end based on the soil mechanical parameters of each soil behavior type, so as to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions. Time-varying reduction factor calculation module: used to obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction factor, liquefaction reduction factor and time-varying corrosion reduction factor, and construct comprehensive time-varying reduction factor through multi-mechanism coupling; Time-varying bearing capacity prediction module: used to correct the initial static ultimate bearing capacity of steel pipe piles based on the comprehensive time-varying reduction coefficient, predict the vertical bearing capacity of steel pipe piles during long-term service, and obtain the time-varying ultimate bearing capacity of steel pipe piles; Safety level assessment module: used to set the bearing capacity assessment threshold based on the time-varying ultimate bearing capacity, dynamically adjust the bearing capacity grading threshold range, match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output the grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile.

[0034] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0035] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples 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 implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0036] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0037] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for estimating the vertical bearing capacity of steel pipe piles, characterized in that, The specific steps include: S1: Conduct static cone penetration tests on the seabed strata where the steel pipe pile foundation is located, obtain experimental data at each depth test point in the static cone penetration test, normalize the experimental data point by point, classify the soil behavior type based on the normalization results, and invert the mechanical parameters of the soil layer of each soil behavior type. S2: Based on the soil mechanical parameters of each soil behavior type, calculate the side friction between the steel pipe pile body and the surrounding soil and the end resistance at the pile end to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions. S3: Obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction coefficient, liquefaction reduction coefficient and time-varying corrosion reduction coefficient, and construct comprehensive time-varying reduction coefficient through multi-mechanism coupling. S4: Based on the comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, the vertical bearing capacity of the steel pipe pile during the long-term service period is predicted, and the time-varying ultimate bearing capacity of the steel pipe pile is obtained. S5: Set the bearing capacity assessment threshold according to the time-varying ultimate bearing capacity, and dynamically adjust the bearing capacity grading threshold range. Match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output the grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile.

2. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 1, characterized in that: During static cone penetration testing, the seabed strata region is selected based on the location of the steel pipe pile foundation. The test is conducted in layers, with a predetermined total depth and equal intervals between layers. The midpoint depth of each predetermined interval layer serves as a test point, and experimental data is collected. The experimental data includes net cone tip resistance, side friction resistance, and static pore water pressure at each test point. The experimental data is then normalized point by point to obtain the normalized cone tip resistance and normalized friction ratio for each test point, forming a data sequence for different test points. The specific formulas for obtaining the normalized cone tip resistance and normalized friction ratio for each test point are as follows: ； in, For the first Depth of each test point for Normalized cone tip resistance at depth for Normalized friction ratio at depth for Net cone tip resistance at depth for Side friction at depth Standard atmospheric pressure for Total overburden stress at depth for Effective overburden stress at depth Stress index; Total overburden stress, i.e., current depth The total weight of all the soil, including seawater, is calculated using the following formula: ； ； in, The density of seawater, It is the acceleration due to gravity. Because of the water depth, The soil weight, yes Static pore water pressure at depth.

3. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 2, characterized in that: Soil layer division is based on normalization results, i.e., according to and Soil behavior was classified by comparing with the soil behavior type chart, and the soil behavior types were divided into clay, sand, and mixed soil. The soil behavior type corresponding to the test point at the midpoint depth of each predetermined detection interval layer represents the soil behavior type of that detection interval layer. At the same time, the mechanical parameters of each interval layer were inverted for each interval layer soil behavior type. The undrained shear strength was inverted for clay interval layer, and the internal friction angle was inverted for sand interval layer. The inversion formulas are as follows: ； in, clay-based interlayer Undrained shear strength at depth For the empirical cone factor, Sandy soil interlayer The internal friction angle at depth; the equivalent friction angle and equivalent cohesion of the mixed soil interlayer are solved iteratively, satisfying the following formula: ； in, Interlayer of mixed soil Equivalent internal friction angle at depth This is a soil behavior index. This is an empirical coefficient. Interlayer of mixed soil Equivalent cohesion at depth.

4. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 1, characterized in that: Calculate the side friction between the steel pipe pile and the surrounding soil, and the end resistance at the pile tip. Divide the steel pipe pile along the depth direction from the soil surface to the pile tip into sections. Each micro-segment is at the same height as the probe's equally spaced layers, with the midpoint depth of each micro-segment being equal to... One-to-one correspondence, the height of each micro-segment is The initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions is obtained: ； in, This is the initial ultimate bearing capacity. for Side friction at the micro-segment For end resistance, For micro-segment numbers, The underwater weight of the steel pipe pile.

5. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 4, characterized in that: Each micro-segment of the steel pipe pile body is located in an interval layer with different soil behavior types. The side skin friction corresponding to the soil behavior type interval layer in which each micro-segment is located is calculated separately, and the end resistance corresponding to different soil behavior type interval layers in which the steel pipe pile tip is located is also different. When the soil behavior type of the micro-segment is clay, the formulas used for the side skin friction and end resistance are as follows: ； When the soil behavior type of the micro-segment is a sandy interlayer, the formulas for side friction and end resistance are as follows: ； When the soil behavior type of the micro-segment is a mixed soil interlayer, the formulas for side friction and end resistance are as follows: ； in, micro-segment The adhesion coefficient at the location, The lateral earth pressure coefficient, The diameter of the steel pipe pile is... The bearing capacity coefficient related to the friction angle of the sandy soil interlayer is... The bearing capacity coefficient related to the friction angle of the mixed soil interlayer is... This refers to the bearing capacity coefficient related to the cohesion of clay-based interlayers. This is the bearing capacity coefficient related to the cohesion of the interlayer in mixed soil.

6. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 2, characterized in that: Equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed were obtained. Equivalent cyclic load reduction factors, liquefaction reduction factors, and time-varying corrosion reduction factors were constructed. A comprehensive time-varying reduction factor was then constructed through multi-mechanism coupling. The formula is as follows: ； in, To incorporate the time-varying reduction factor, This is the liquefaction reduction factor. The time-varying corrosion reduction factor, liquefaction reduction factor, and time-varying corrosion reduction factor are constructed using the following approach: Historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed are obtained. This historical equivalent cyclic load experimental data includes: the annual average number of equivalent cyclic loads in the construction sea area, the annual average equivalent cyclic load stress ratio, and the annual average equivalent cyclic load resistance ratio. The calculation formulas for the equivalent cyclic load reduction factor, liquefaction reduction factor, and time-varying corrosion reduction factor are as follows: ； ； in, This is the equivalent cyclic load reduction factor. For cyclic load empirical coefficients, The average equivalent number of cycles, This is the empirical coefficient for liquefaction reduction. The annual average equivalent cyclic load stress ratio, The annual average equivalent cyclic load resistance ratio. This represents the initial wall thickness of the steel pipe pile. The length of the steel pipe pile. For corrosion depth, It is a time variable.

7. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 6, characterized in that: Based on the aforementioned comprehensive time-varying reduction coefficient, the initial static ultimate bearing capacity of the steel pipe pile is corrected, and the vertical bearing capacity of the steel pipe pile during its long-term service life is predicted, thus obtaining the time-varying ultimate bearing capacity of the steel pipe pile, as shown in the following formula: ； in, This is the initial ultimate bearing capacity. The time-varying ultimate bearing capacity, i.e. Limit load capacity at all times.

8. The method for estimating the vertical bearing capacity of steel pipe piles according to claim 7, characterized in that: Based on the time-varying ultimate bearing capacity, a bearing capacity assessment threshold is set, and the bearing capacity grading threshold range is dynamically adjusted. The time-varying ultimate bearing capacity is matched with the dynamic bearing capacity grading threshold range, and a grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile is output. The specific logic is as follows: If Therefore, it is safe and has sufficient load-bearing capacity; like If so, it's normal; the steel pipe pile is in a normal state. If the load-bearing capacity is below or close to the failure threshold, an early warning will be issued; where, This is the preset load-bearing capacity threshold.

9. A system for estimating the vertical bearing capacity of steel pipe piles, characterized in that: The steel pipe pile vertical bearing capacity estimation system is used to execute the steel pipe pile vertical bearing capacity estimation method according to any one of claims 1-8, including: The exploration and data processing module is used to conduct static cone penetration tests on the seabed strata required for steel pipe pile foundations, obtain experimental data at each depth test point in the static cone penetration test, normalize the experimental data point by point, classify soil behavior types based on the normalization results, and invert the mechanical parameters of soil layers of each soil behavior type. Static bearing capacity calculation module: used to calculate the side friction resistance between the steel pipe pile body and the surrounding soil and the end resistance of the pile end based on the soil mechanical parameters of each soil behavior type, so as to obtain the initial static ultimate bearing capacity of the steel pipe pile under ideal static conditions. Time-varying reduction factor calculation module: used to obtain historical equivalent cyclic load experimental data of waves in the sea area where steel pipe piles are constructed, construct equivalent cyclic load reduction factor, liquefaction reduction factor and time-varying corrosion reduction factor, and construct comprehensive time-varying reduction factor through multi-mechanism coupling; Time-varying bearing capacity prediction module: used to correct the initial static ultimate bearing capacity of steel pipe piles based on the comprehensive time-varying reduction coefficient, predict the vertical bearing capacity of steel pipe piles during long-term service, and obtain the time-varying ultimate bearing capacity of steel pipe piles; Safety level assessment module: used to set the bearing capacity assessment threshold based on the time-varying ultimate bearing capacity, dynamically adjust the bearing capacity grading threshold range, match the time-varying ultimate bearing capacity with the dynamic bearing capacity grading threshold range, and output the grading evaluation result for the vertical bearing capacity to be estimated for the steel pipe pile.

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