Method for judging damage state of soil body around offshore wind power pile foundation
By constructing a fault vibration contour map through indoor soil cyclic loading tests and equivalent cyclic vibration relationship, the high cost and complexity of soil failure assessment for offshore wind turbine pile foundations were solved, and a simple and accurate judgment of soil failure status was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies for assessing soil damage around offshore wind turbine foundations suffer from high testing costs, long testing cycles, and poor applicability. Furthermore, complex numerical simulation methods are computationally intensive and difficult to promote and apply.
By obtaining the cumulative cyclic shear strain map through indoor soil cyclic loading tests, and combining it with complex wave force load data, an equivalent cyclic vibration relationship is established, and a failure vibration contour map is constructed to determine the soil failure state.
This paper presents a simple and widely applicable method that can accurately determine the soil failure state, reduce costs, improve universality, and is suitable for engineering design at different sites.
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Figure CN121994692A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of marine wind power engineering technology, specifically to a method for judging the damage state of the soil surrounding the foundation of offshore wind turbine piles. Background Technology
[0002] Offshore wind power, as a key pathway for my country's energy structure adjustment, is gradually moving towards deep-sea and high-power applications. In this development process, wind turbine foundations are subjected to continuous, complex cyclic loads from wind, waves, and currents. Furthermore, the soil at offshore sites is mostly soft clay, making it particularly sensitive to cyclic loads. The interaction between the wind turbine pile foundation and the surrounding soil directly determines the stability, bearing capacity, and long-term operational safety of the foundation structure. Under long-term cyclic loads, the soil is prone to cumulative plastic deformation, stiffness degradation, and strength reduction, leading to weakening of the pile-soil interface, excessive foundation settlement, and even overall instability, severely impacting the safety and service life of offshore wind turbine pile structures.
[0003] Currently, there are two main methods for assessing the damage and deformation of the soil surrounding wind turbine pile foundations under cyclic loading:
[0004] One approach is to conduct cyclic load tests on the interaction between the structure and the soil directly on site. While this method is intuitive, it requires a large number of repeated tests, which is not only extremely costly and time-consuming, but also suffers from poor universality due to the differences in soil properties, making it unsuitable for engineering designs at different sites.
[0005] Secondly, by conducting numerical simulation of soil and combining it with complex cyclic constitutive models for finite element or finite difference numerical simulation prediction, this method is not only complex in modeling and calculation processes and difficult to guarantee prediction accuracy, but also requires extremely high professional skills from engineering designers, is difficult to operate, and is difficult to promote and apply in actual engineering design.
[0006] Therefore, developing a method that is data-driven, has strong engineering applicability, and can quantitatively determine the soil failure state under cyclic loading has become an urgent need in the field of offshore wind power pile foundation design and safety assessment. Summary of the Invention
[0007] To address the shortcomings of existing technologies, this invention provides a method for judging the damage state of soil surrounding offshore wind turbine pile foundations.
[0008] Therefore, the present invention adopts the following technical solution:
[0009] A method for judging the failure state of soil surrounding offshore wind turbine pile foundations, characterized by the following steps:
[0010] S1, Conduct indoor cyclic loading tests on soil and obtain the cumulative cyclic shear strain diagram:
[0011] Uncirculated soil around the offshore wind turbine pile foundation was collected, and a systematic indoor soil cyclic loading test was conducted. Contour distribution maps of different cyclic shear strains were plotted with the cyclic shear stress ratio as the vertical axis and the cyclic vibration number as the horizontal axis.
[0012] In the contour plot, obtain the cyclic shear strain when the cyclic vibration order is 1. Plot the cyclic shear strain at this point by relating it to the cyclic shear stress ratio. Graph showing the relationship between cyclic shear stress ratio and its variation;
[0013] The two graphs are matched according to the ratio of cyclic shear stress to form a complete cumulative cyclic shear strain graph;
[0014] S2: Obtain the complex wave force load data of the undisturbed soil over a period of time, and convert it into a set of cyclic shear stress ratio data sorted from smallest to largest; find the minimum cyclic shear stress ratio and its corresponding cyclic vibration number; based on the cyclic shear strain accumulation diagram obtained in S1, obtain the equivalent cyclic vibration number corresponding to the next cyclic shear stress ratio; repeat the same operation until the final equivalent cyclic vibration number corresponding to the maximum cyclic shear stress ratio is obtained. ;
[0015] S3, indoor cyclic triaxial tests were conducted on the undisturbed soil surrounding the offshore wind turbine pile foundation to obtain the corresponding failure vibration frequencies under different working conditions. The failure frequency was obtained with the horizontal axis representing the average shear stress ratio and the vertical axis representing the cyclic shear stress ratio. Contour map;
[0016] S4, based on the measured average shear stress of the undisturbed soil in the target area. In the contour map of the failure vibration order obtained in S3, find the corresponding failure vibration order. The final equivalent cyclic order obtained from S2 With the destruction of vibration order By comparing the results, we can determine whether the soil has been damaged.
[0017] In step S1 above:
[0018] The cyclic shear stress ratio With cyclic vibration Cyclic shear strain Contour maps can represent the ratio of cyclic shear stress to soil when the cyclic shear strain is the same. With cyclic vibration The changing relationship;
[0019] Wherein, the cyclic shear stress ratio This represents the ratio of the cyclic shear stress on the undrained soil mass to twice its normalized undrained shear strength. The cyclic shear stress on the undisturbed soil mass. It represents the undrained shear strength of the original soil mass.
[0020] In step S2 above, the complex wave force load data includes the load magnitude and the number of times the load occurs; the wave force load is treated as cyclic shear stress. According to the cyclic shear stress ratio The definition converts the wave force load into a cyclic shear stress ratio, resulting in a set of cyclic shear stress ratio data sorted from smallest to largest.
[0021] The method for obtaining the equivalent cyclic order in step S2 above is as follows:
[0022] Based on a set of cyclic shear stress ratios sorted from smallest to largest, the minimum cyclic shear stress ratio and its corresponding cycle number are found. The corresponding point B is located in the cumulative cyclic shear strain diagram obtained in S1. Based on the cyclic shear strain at point B... The contour lines correspond to the cyclic shear strain. value;
[0023] Find the next cyclic shear stress ratio data, in the cyclic shear strain Under the condition that the shear strain remains unchanged, in the current cycle Move along the contour line to find the data point C corresponding to the cyclic shear stress ratio data;
[0024] The instant the cyclic shear stress ratio increases, the cyclic shear strain of the soil changes, producing an increment. ;
[0025] With the cyclic shear stress ratio remaining constant, the data point C is moved laterally to find the current cyclic shear strain and add an increment. The value after that corresponds to the cyclic shear strain Data point D on the contour line, the value of the cycle number corresponding to data point D is the current equivalent cycle number. Data point D represents the initial state for continuing the cycle under the next cycle shear stress ratio.
[0026] The specific operation of step S3 above is as follows:
[0027] Extensive indoor cyclic loading tests were conducted on the undisturbed soil surrounding the pile foundations in the target area to measure cyclic shear strain. A failure threshold of 15% was set as the criterion for soil failure, and the corresponding failure vibration frequencies under different working conditions were obtained. Then, the destruction order is obtained by fitting. Contour map; same failure vibration order The contour lines are divided into three stages.
[0028] The different working conditions mentioned in step S3 above refer to different average shear stresses. With cyclic shear stress .
[0029] In step S3 above:
[0030] The fitting formulas for the first and second stages are:
[0031] (1)
[0032] Third-stage fitting formula:
[0033] (2).
[0034] The specific operation of step S2 above is as follows:
[0035] Based on the measured average shear stress of the undisturbed soil in the target area The failure frequency obtained in S3 is the ratio of the maximum cyclic shear stress described in S2. Locate the corresponding destruction order in the contour map. The final equivalent cyclic order obtained from S22 With the destruction of vibration order Compare the soil samples to determine its failure state and extent:
[0036] when ≥ At that time, it was determined that the soil had been damaged;
[0037] when < At that time, it was determined that the soil had not been damaged.
[0038] Compared with the prior art, the present invention has the following beneficial effects:
[0039] 1. The method of the present invention effectively solves the problem of high cost caused by large equipment investment, low personnel utilization rate and repeated testing in traditional engineering field cyclic load tests.
[0040] 2. The method of the present invention has high universality, is not limited by specific site conditions, avoids the problems of cumbersome modeling and high computational difficulty in numerical simulation of complex constitutive models, and can guarantee accuracy.
[0041] 3. The method of this invention is driven by indoor test data, is easy to operate and highly adaptable, and can provide accurate and reliable quantitative basis for the design optimization of offshore wind power pile foundation engineering and the early warning of operation risks throughout the entire life cycle. The method has strong engineering practicality and significant promotion value, and provides strong technical support for the high-quality development of the industry. Attached Figure Description
[0042] Figure 1 This is a flowchart of the soil failure state determination method in an embodiment of the present invention;
[0043] Figure 2 This is a schematic diagram illustrating the principle of cyclic shear strain accumulation in an embodiment of the present invention;
[0044] Figure 3 This is a schematic diagram of the equivalent cyclic load in an embodiment of the present invention;
[0045] Figure 4 This is a contour map of the vibration order of soft clay failure in an embodiment of the present invention. Detailed Implementation
[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the following embodiments are only some embodiments of the present invention. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0047] like Figure 1 As shown, the method for judging the failure state of soil surrounding offshore wind turbine pile foundations according to the present invention includes the following specific steps:
[0048] S1. Conduct cyclic loading tests on the soil to obtain the cumulative cyclic shear strain diagram.
[0049] Uncirculated soil samples were collected from the area surrounding the offshore wind turbine foundation, and a systematic indoor cyclic triaxial test (soil cyclic loading test) was conducted to plot the cyclic shear stress ratio. With cyclic vibration Cyclic shear strain Contour maps can represent the ratio of cyclic shear stress to cyclic shear strain in soil when the cyclic shear strain is the same. With cyclic vibration The relationship between the changes; in the contour map, obtain the cyclic vibration order. When =1, cyclic shear strain Ratio of cyclic shear stress The correspondence, and thus obtain When =1, the cyclic shear strain of the soil With cyclic shear stress ratio The graph shows the relationship between the two graphs. The graphs are then compared based on the ratio of cyclic shear stress. Correspondingly, a complete cumulative cyclic shear strain diagram is formed.
[0050] Wherein, the cyclic shear stress ratio This represents the ratio of the cyclic shear stress on the undrained soil mass to twice its normalized undrained shear strength. The cyclic shear stress on the undisturbed soil mass. It represents the undrained shear strength of the original soil mass.
[0051] In one embodiment of the present invention, the cyclic shear strain accumulation diagram is as follows: Figure 2 As shown in the figure on the left, the cyclic shear strain of the soil under one cycle is obtained under a cyclic shear stress ratio of 0 to 0.8. The right figure shows the cyclic shear strain. Contour maps can represent the cyclic shear strain generated in the soil. At that time, the cyclic shear stress ratio Relationship with the number of cycles.
[0052] S2, based on the cumulative cyclic shear strain diagram obtained in S1, establishes the equivalent relationship between complex wave loads and cyclic vibrations, and obtains the final equivalent cyclic vibrations. The specific steps are as follows:
[0053] S21. Obtain the complex wave force load data of the undisturbed soil surrounding the offshore wind turbine pile foundation over a period of time, and convert it into cyclic shear stress ratio data. The complex wave force load data includes the load magnitude and the number of times the load occurs, and is sorted in ascending order of load magnitude. Under a single load, the strain generated in the soil is fixed; therefore, the order in which the loads occur over a period of time has no effect on the final cumulative cyclic strain generated in the soil.
[0054] The wave force load is the cyclic shear stress. According to the cyclic shear stress ratio The definition can convert wave force load into cyclic shear stress ratio, resulting in a set of cyclic shear stress ratio data sorted from smallest to largest.
[0055] S22, based on the cyclic shear stress ratio data obtained in S21, obtain the minimum cyclic shear stress ratio and its corresponding cyclic vibration number. Find the corresponding point B in the cyclic shear strain accumulation diagram obtained in S1, and determine the cyclic shear strain at point B. The contour lines correspond to the cyclic shear strain. value.
[0056] For example, such as Figure 2 As shown, the minimum cyclic shear stress ratio is =0.3, cycle number =90, in Figure 2 Find the corresponding point B, and obtain the corresponding shear strain of the soil at this time. =2.5%.
[0057] S23, find the next cyclic shear stress ratio data from the cyclic shear stress ratio data obtained in S21, and calculate the cyclic shear strain. Under the condition that the shear strain remains unchanged in the current cycle Move along the contour line to find the data point C corresponding to the next cyclic shear stress ratio data.
[0058] At the instant the cyclic shear stress ratio increases, the cyclic shear strain of the soil will change, producing an increment. According to the cycle number When =1, cyclic shear strain Ratio of cyclic shear stress The correspondence was calculated to obtain .
[0059] With the cyclic shear stress ratio remaining constant, the data point C is moved laterally to find the current cyclic shear strain and add an increment. The value after that corresponds to the cyclic shear strain Data point D on the contour line corresponds to a cyclic vibration number equal to the current cyclic shear stress compared to the equivalent cyclic vibration number of the data point. .
[0060] For example, such as Figure 2 As shown, when the cyclic shear stress ratio As the value increases from 0.3 to 0.45, the cyclic shear strain along the soil... The contour line at 2.5% moves to... Point C corresponds to =0.45. =0.64%, at which point the cyclic shear strain of the soil is... Reaching 3.14%, corresponding to point D ( =3.14%), thus obtaining the equivalent number of cycles corresponding to the current cyclic shear stress ratio data. =7.
[0061] S24, data point D represents the initial state of continuing the cycle under the next cyclic shear stress ratio described in S22. Based on the cyclic shear stress ratio data obtained in S21, the same operations as S22~S23 are repeated until the final equivalent number of cycles corresponding to the maximum cyclic shear stress ratio is obtained. .
[0062] For example, in =0.45, looped 103 times, and =0.45 is the maximum cyclic shear stress ratio, then the final equivalent number of cycles is... =110.
[0063] like Figure 3 As shown, the above method can achieve accurate equivalence under any complex cyclic load history.
[0064] S3, construct a contour map of soil failure vibration order.
[0065] Extensive indoor cyclic triaxial tests (soil cyclic loading tests) were conducted on the undisturbed soil surrounding the offshore wind turbine pile foundations to measure cyclic shear strain ( A failure rate of 15% was used as the threshold for soil failure, and the corresponding failure vibration frequencies under different working conditions were obtained. The different working conditions refer to different average shear stresses. (In a fixed environment, (for fixed values) and cyclic shear stress Based on the obtained data, the average shear stress ratio on the horizontal axis was obtained through fitting (interpolation and extrapolation). The vertical axis represents the cyclic shear stress ratio. Destructive vibrations Contour map.
[0066] Same damaging vibration order The contour lines can be divided into three stages, among which:
[0067] First and second stage fitting formulas:
[0068] (1)
[0069] Third-stage fitting formula:
[0070] (2)
[0071] For example, such as Figure 4 As shown, a system corresponding to... The contour maps of the failure vibration order =10, 100, and 1000 are shown in Table 1. The parameters in the contour fitting formula are shown in Table 1.
[0072] Table 1
[0073]
[0074] S4, Determination of soil damage level.
[0075] Based on the measured average shear stress of the undisturbed soil surrounding the offshore wind turbine foundation... Calculate the average shear stress ratio Based on the maximum cyclic shear stress ratio described in S2, the failure vibration number obtained in S3 is... In the contour map, find the corresponding point and determine the failure order of that point. Contour lines determine the order of failure vibrations. .
[0076] The final equivalent cyclic order obtained from S22 With the above-mentioned destructive vibration order Compare the soil samples to determine its failure state and extent:
[0077] when ≥ At that time, it was determined that the soil had been damaged; when < At that time, it was determined that the soil had not been damaged.
[0078] Example
[0079] Project Background: An offshore wind farm is located in the nearshore area of Tianjin Binhai New Area. The wind turbines adopt monopile foundations. The site strata are mainly soft clay from Tianjin Binhai. The undrained shear strength was measured. =38kPa, the soil is subjected to complex cyclic loads with varying amplitudes of wind, waves and currents over a long period. To assess the stability of the soil surrounding the pile foundation during 50 years of wind turbine operation, the method of this invention is used to determine the soil failure state.
[0080] S1. Collect undisturbed soil around the pile foundation in the nearshore area of Tianjin Binhai New Area, conduct systematic soil cyclic loading tests, and draw the cumulative cyclic shear strain diagram.
[0081] S2, based on the cumulative cyclic shear strain diagram obtained in S1, establishes the equivalent relationship between complex wave loads and cyclic vibrations, and obtains the final equivalent cyclic vibrations. .
[0082] Using meteorological and hydrological monitoring data (data in this embodiment comes from the National Marine Science Data Center website https: / / mds.nmdis.org.cn / pages / dataViewDetail.html?dataSetId=37) and load calculations, complex wave load data for a 50-year operational period were obtained and converted into cyclic shear stress ratios. Specific data are shown in Table 2.
[0083] Table 2
[0084]
[0085] After experiencing loads ranging from 0.084 to 0.171, the cyclic shear strain at this point is obtained. =1.85%. Next cycle shear stress ratio =0.21, along The contour line with a value of 1.85% was shifted to... =0.21 corresponds to the data point, and the result is calculated. =0.3%, accumulating new =2.15%, corresponding to 4158 cyclic vibrations; based on this, according to the cyclic shear stress ratio =0.21, applied for 357 cycles (4158+357), cyclic shear strain =2.78%, this cumulative strain is used as the shear strain for the next cycle. Starting with an initial state of 0.249, and so on, the final equivalent cycle number is obtained. =427.
[0086] Transform all complex loads into a uniform stress level Final equivalent cyclic number of vibrations at 0.3 =427 cycles. The cumulative cyclic shear strain plot shows that when the number of cycles is 427, the cyclic shear strain is 7.9%.
[0087] In-situ cyclic loading tests were conducted on-site, applying cyclic shear stress ratios to the monopile structure of offshore wind power plants. A cyclic load of 0.3 was applied to simulate the periodic action of waves. The strain of the soil around the pile was monitored. It was found that when the soil strain reached 7.9%, the number of cycles was 431. This indicates that the equivalent number of cycles obtained by the method of the present invention is close to the field test data and is more on the safe side.
[0088] In-situ cyclic loading tests were conducted on-site, applying 427 cycles of shear stress ratio to the offshore wind turbine monopile structure. A cyclic load of 0.3 was applied to simulate the periodic action of waves. The strain of the soil around the pile was monitored. It was found that after 427 cycles, the cyclic shear strain of the soil was 8.1%, indicating that the strain corresponding to the equivalent number of cycles obtained by the method of the present invention is close to the field test data and is more on the safe side.
[0089] S3, constructed as follows Figure 4 The image shows the contour map of vibration levels indicating the failure of soft clay in Binhai, Tianjin.
[0090] S4, In this embodiment, the average shear stress is 0, the average shear stress ratio is 0, and the cyclic shear stress ratio is obtained from the failure vibration contour map. =0.3 corresponding to the destruction frequency =631 times. Clearly, =427 is less than =631, the soil was not damaged.
[0091] In summary, the accuracy and practicality of the method of this invention in judging the failure of soil around wind turbine pile foundations under complex cyclic loading have been fully verified. Furthermore, it has advantages such as small deviation between calculated results and actual measurements, ease of operation, and adaptability to engineering needs, providing reliable technical support for the safety assessment of offshore wind power projects.
Claims
1. A method for judging the failure state of soil surrounding offshore wind turbine pile foundations, characterized in that, The steps are as follows: S1, Conduct indoor cyclic loading tests on soil and obtain the cumulative cyclic shear strain diagram: Uncirculated soil around the offshore wind turbine pile foundation was collected, and a systematic indoor soil cyclic loading test was conducted. Contour distribution maps of different cyclic shear strains were plotted with the cyclic shear stress ratio as the vertical axis and the cyclic vibration number as the horizontal axis. In the contour plot, obtain the cyclic shear strain when the cyclic vibration order is 1. Plot the cyclic shear strain at this point by relating it to the cyclic shear stress ratio. Graph showing the relationship between cyclic shear stress ratio and its variation; The two graphs are matched according to the ratio of cyclic shear stress to form a complete cumulative cyclic shear strain graph; S2: Obtain the complex wave force load data of the undisturbed soil over a period of time, and convert it into a set of cyclic shear stress ratio data sorted from smallest to largest; find the minimum cyclic shear stress ratio and its corresponding cyclic vibration number; based on the cyclic shear strain accumulation diagram obtained in S1, obtain the equivalent cyclic vibration number corresponding to the next cyclic shear stress ratio; repeat the same operation until the final equivalent cyclic vibration number corresponding to the maximum cyclic shear stress ratio is obtained. ; S3, indoor cyclic triaxial tests were conducted on the undisturbed soil surrounding the offshore wind turbine pile foundation to obtain the corresponding failure vibration frequencies under different working conditions. The failure frequency was obtained with the horizontal axis representing the average shear stress ratio and the vertical axis representing the cyclic shear stress ratio. Contour map; S4, based on the measured average shear stress of the undisturbed soil in the target area. In the contour map of the failure vibration order obtained in S3, find the corresponding failure vibration order. ; The final equivalent cyclic order obtained from S2 With the destruction of vibration order By comparing the results, we can determine whether the soil has been damaged.
2. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 1, characterized in that, In step S1: The cyclic shear stress ratio With cyclic vibration Cyclic shear strain Contour maps can represent the ratio of cyclic shear stress to soil when the cyclic shear strain is the same. With cyclic vibration The changing relationship; Wherein, the cyclic shear stress ratio This represents the ratio of the cyclic shear stress on the undrained soil mass to twice its normalized undrained shear strength. The cyclic shear stress on the undisturbed soil mass. It represents the undrained shear strength of the original soil mass.
3. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 2, characterized in that: In step S2, the complex wave force load data includes the load magnitude and the number of times the load occurs; The wave force load is treated as cyclic shear stress. According to the cyclic shear stress ratio The definition converts the wave force load into a cyclic shear stress ratio, resulting in a set of cyclic shear stress ratio data sorted from smallest to largest.
4. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 3, characterized in that, The method for obtaining the equivalent cyclic order in step S2 is as follows: Based on a set of cyclic shear stress ratios sorted from smallest to largest, the minimum cyclic shear stress ratio and its corresponding cycle number are found. The corresponding point B is located in the cumulative cyclic shear strain diagram obtained in S1. Based on the cyclic shear strain at point B... The contour lines correspond to the cyclic shear strain. value; Find the next cyclic shear stress ratio data, in the cyclic shear strain Under the condition that the shear strain remains unchanged, in the current cycle Move along the contour line to find the data point C corresponding to the cyclic shear stress ratio data; The instant the cyclic shear stress ratio increases, the cyclic shear strain of the soil changes, producing an increment. ; With the cyclic shear stress ratio remaining constant, the data point C is moved laterally to find the current cyclic shear strain and add an increment. The value after that corresponds to the cyclic shear strain Data point D on the contour line, the value of the cycle number corresponding to data point D is the current equivalent cycle number. ; Data point D represents the initial state for continuing the cycle under the next cycle shear stress ratio.
5. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 1, characterized in that, The specific operation of step S3 is as follows: Extensive indoor cyclic loading tests were conducted on the undisturbed soil surrounding the pile foundations in the target area to measure cyclic shear strain. A failure threshold of 15% was set as the criterion for soil failure, and the corresponding failure vibration frequencies under different working conditions were obtained. Then, the destruction order is obtained by fitting. Contour map; same failure vibration order The contour lines are divided into three stages.
6. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 5, characterized in that: The different working conditions mentioned in step S3 refer to different average shear stresses. With cyclic shear stress .
7. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 6, characterized in that, In step S3: The fitting formulas for the first and second stages are: （1） Third-stage fitting formula: （2）。 8. The method for judging the failure state of the soil surrounding the offshore wind turbine pile foundation according to claim 7, characterized in that, The specific operation of step S2 is as follows: Based on the measured average shear stress of the undisturbed soil The failure frequency obtained in S3 is the ratio of the maximum cyclic shear stress described in S2. Locate the corresponding destruction vibration in the contour map. The final equivalent cyclic order obtained from S22 With the destruction of vibration order Compare the soil samples to determine its failure state and extent: when ≥ At that time, it was determined that the soil had been damaged; when < At that time, it was determined that the soil had not been damaged.