A wind power test bench foundation safety assessment method, system, equipment and medium

Abstract

The present invention proposes a safety assessment method, system, equipment and medium for a wind turbine test bench foundation. The assessment method obtains the inherent parameters of the test bench foundation and the extreme operating condition parameters, operating condition parameters and seismic condition parameters throughout its entire life cycle, and uses a pre-constructed finite element model to simulate the stress conditions of the test bench foundation during operation, thereby obtaining the ultimate load and fatigue load of the test bench foundation. Based on the inherent parameters, extreme operating condition parameters, operating condition parameters, seismic condition parameters, ultimate load and fatigue load, the test bench foundation is subjected to ultimate strength verification and fatigue strength verification, thereby achieving an accurate assessment of the design safety of the test bench foundation.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a safety assessment method, system, equipment and medium for a wind power test bench foundation. Background Art

[0002] With the maturity of wind power technology, the wind power industry has entered a period of rapid growth. Correspondingly, the capacity and size of wind turbines continue to increase. Before a wind turbine is put on the market, in order to verify the working performance of the core components, wind turbine manufacturers often need to conduct 1:1 physical working condition tests on the core components, especially the blades and transmission chains, on a large test bench. As the most basic structure for the operation of the test bench, the test bench foundation should provide sufficient rigid support and bear all loads (including gravity, reaction force, etc.). In order to effectively evaluate the safety performance of the test bench or evaluate the maximum testing capacity of the built test bench, a standardized test bench safety assessment process is urgently needed.

[0003] Currently, most large-scale test benches for wind turbines are blade test benches. The design of transmission chain and blade test benches lacks corresponding standards to guide design and verification, and safety factors are often conservative. As wind turbine capacity gradually increases, higher requirements are placed on the testing capabilities of the test bench. The test bench foundation must withstand greater loads, and as wind turbine capacity increases nonlinearly, the previous design of the test bench by increasing the safety factor has greatly increased the difficulty of construction and construction. Currently, the design and verification of the foundation mainly refers to the corresponding standards of the construction industry, and there is no unified calculation and verification process. In addition, wind turbine test benches such as transmission chain test benches and blade test benches need to experience dynamic loads, and the impact of dynamic loads needs to be considered during the design and verification of the test bench foundation. Therefore, there is a lack of a unified safety assessment method. Summary of the Invention

[0004] In order to solve the problem that the design safety verification of wind turbine test bench foundation currently lacks a unified safety assessment method and process, and the calculation verification results are inaccurate, the present invention proposes a safety assessment method for wind turbine test bench foundation, which includes:

[0005] Obtaining inherent parameters of the test bench foundation and extreme operating condition parameters, operating condition parameters, and seismic condition parameters throughout its life cycle;

[0006] Substituting the extreme working condition parameters, operating working condition parameters and earthquake working condition parameters into a pre-built finite element model respectively, using the finite element model to perform a stress simulation on the test bench foundation to obtain the ultimate load and fatigue load of the test bench foundation;

[0007] Performing ultimate strength check and fatigue strength check on the test bench foundation based on the inherent parameters, extreme working condition parameters, operating working condition parameters, earthquake working condition parameters, ultimate load and fatigue load;

[0008] The inherent parameters include soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation.

[0009] Preferably, the ultimate load includes the maximum axial tensile load and the maximum axial compressive load of the pile leg, and the fatigue load includes the maximum compressive stress and the minimum compressive stress of the concrete and the maximum tensile stress and the minimum tensile stress of the steel bar.

[0010] Preferably, the ultimate strength check and fatigue strength check of the test bench foundation based on the extreme working condition parameters, operating working condition parameters, earthquake working condition parameters, ultimate load and fatigue load includes:

[0011] Performing a bearing capacity check on the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs;

[0012] The fatigue strength of the steel-concrete part of the test bench foundation is checked based on the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar. The steel-concrete part includes the pile foundation cap, the supporting structure on the upper part of the pile foundation cap and the anchoring device inside the pile foundation cap.

[0013] Preferably, checking the bearing capacity of the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs comprises:

[0014] The maximum tensile bearing capacity and the maximum compressive bearing capacity of the pile leg are calculated based on the soil mechanics parameters and the maximum tensile bearing capacity calculation formula and the maximum compressive bearing capacity calculation formula;

[0015] The maximum axial tensile load and the maximum axial compressive load are compared with the maximum tensile bearing capacity and the maximum compressive bearing capacity respectively. If the maximum axial tensile load and the maximum axial compressive load are respectively less than the maximum tensile bearing capacity and the maximum compressive bearing capacity, the bearing capacity of the pile leg is qualified; otherwise, the bearing capacity of the pile leg is unqualified.

[0016] Preferably, the maximum tensile bearing capacity calculation formula is as follows:

[0017]

[0018] Where, F a is the maximum tensile bearing capacity of a single pile, R s is the lateral friction resistance, R bis the pile end resistance, m is the tensile bearing capacity reduction factor, fs i is the characteristic value of the ultimate friction resistance of the rock and soil around the pile in the i-th soil layer, f p is the characteristic value of the ultimate end resistance of the rock and soil at the pile end of the i-th soil layer, thk i is the thickness of the soil layer in the ith geological profile, D is the diameter of the pile leg, and n is the total number of soil layers in the geological profile.

[0019] Preferably, the maximum compressive bearing capacity calculation formula is as follows:

[0020]

[0021] Where, F a ′ is the maximum compression bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile tip resistance, c is the compression bearing capacity reduction factor, fs i is the characteristic value of the ultimate friction resistance of the rock and soil around the pile in the i-th soil layer, f p is the characteristic value of the ultimate end resistance of the rock and soil at the pile end of the i-th soil layer, thk i is the thickness of the soil layer in the ith geological profile, D is the diameter of the pile leg, and n is the total number of soil layers in the geological profile.

[0022] Preferably, the fatigue strength check of the steel-concrete part of the test bench foundation based on the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar includes:

[0023] The maximum number of loads that concrete can withstand under alternating stress is calculated based on the maximum compressive stress and minimum compressive stress of concrete combined with the formula for calculating the maximum number of loads of concrete. The maximum number of loads that steel bars can withstand under alternating stress is calculated based on the maximum and minimum tensile stress of steel bars combined with the SN curve formula of steel bars.

[0024] If the ratio of the actual loading times of concrete to the maximum loading times that concrete can withstand, and the ratio of the actual loading times of steel bars to the maximum loading times that steel bars can withstand are both less than 1, then the fatigue strength of the steel-concrete structure is qualified; otherwise, the fatigue strength of the steel-concrete structure is unqualified.

[0025] Preferably, the maximum load times of concrete are calculated as follows:

[0026]

[0027] Where N1 is the maximum load times that concrete can withstand under alternating stress, E cd，max is the maximum compressive stress level of concrete, R i is the stress ratio of concrete.

[0028] Preferably, the curve formula is as follows:

[0029]

[0030] Where Δσ is the amplitude of the alternating stress, N is the maximum number of loads that the steel bar can withstand under the alternating stress, and N * is 10 6 , k1 and k2 are logN on the SN curve of the steel bar * The slope of the curve on both sides of the corresponding position.

[0031] Preferably, the safety assessment method further comprises:

[0032] Performing modal calculation on the test bench foundation using the finite element model to obtain the modal frequency of the test bench foundation;

[0033] The modal frequency is compared with the rotation frequency range of the wind turbine to be tested. If the modal frequency falls within the rotation frequency range, the stiffness of the test bench foundation is unqualified; otherwise, the stiffness of the test bench foundation is qualified.

[0034] Preferably, the safety assessment method further comprises:

[0035] Using shell elements to establish finite element models of the pile foundation cap and the supporting structure, and using beam elements to establish a finite element model of the pile legs;

[0036] Setting boundary conditions for the finite element model of the pile leg, wherein the boundary conditions include a horizontal stiffness coefficient, a vertical stiffness coefficient, and a rotational stiffness coefficient;

[0037] A finite element model of the test bench foundation is constructed based on the finite element models of the pile foundation cap and the supporting structure, the finite element model of the pile legs, and the boundary conditions.

[0038] Preferably, setting boundary conditions for the finite element model of the pile leg includes:

[0039] The horizontal stiffness coefficient, vertical stiffness coefficient and rotational stiffness coefficient are set based on the structural parameters and mechanical performance parameters of the pile leg in combination with the horizontal stiffness coefficient formula, the pile end vertical stiffness coefficient formula and the rotational stiffness coefficient formula.

[0040] Preferably, the horizontal stiffness coefficient is as follows:

[0041]

[0042] Among them, K his the horizontal stiffness coefficient arranged along the pile length, L is the buried depth of the pile leg, T is the elastic length, EI is the bending stiffness, E is the elastic modulus, and I is the section moment of inertia.

[0043] Preferably, the vertical stiffness coefficient of the pile end is as follows:

[0044]

[0045] Among them, K v is the vertical stiffness coefficient of the pile tip, N p is the vertical compressive load borne by the pile, s is the settlement value of the pile under the vertical compressive load, Q h is the settlement load, L c To calculate the length, D is the diameter of the pile leg, A is the net cross-sectional area of ​​the pile, and E is the elastic modulus.

[0046] Preferably, the rotational stiffness coefficient is as follows:

[0047]

[0048] Among them, K θ is the rotational stiffness coefficient, L is the buried depth of the pile leg, T is the elastic length, EI is the bending stiffness, E is the elastic modulus, and I is the section moment of inertia.

[0049] Preferably, the shell element is 4-node.

[0050] Based on the same inventive concept, the present invention also proposes a safety assessment system for a wind turbine test bench foundation, the safety assessment system comprising:

[0051] An acquisition module, used to obtain the inherent parameters of the test bench foundation and the extreme working condition parameters, operating condition parameters and earthquake working condition parameters throughout the entire life cycle;

[0052] a simulation module, configured to substitute the extreme working condition parameters, the operating working condition parameters, and the earthquake working condition parameters into a pre-built finite element model, perform a stress simulation on the test bench foundation using the finite element model, and obtain the ultimate load and fatigue load of the test bench foundation;

[0053] a verification module for performing ultimate strength verification and fatigue strength verification on the test bench foundation based on the inherent parameters, extreme operating condition parameters, operating condition parameters, earthquake condition parameters, ultimate loads, and fatigue loads;

[0054] The inherent parameters include soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation.

[0055] Preferably, the verification module includes:

[0056] An ultimate strength checking unit, configured to check the bearing capacity of the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs;

[0057] The fatigue strength verification unit is used to verify the fatigue strength of the steel-concrete portion of the test bench foundation based on the maximum and minimum compressive stresses of the concrete and the maximum and minimum tensile stresses of the steel bars. The steel-concrete portion includes the pile cap, anchoring device, and supporting structure above the pile cap.

[0058] Based on the same inventive concept, the present invention also proposes a computer device, comprising: one or more processors; the processor is used to store one or more programs; when the one or more programs are executed by the one or more processors, a safety assessment method for a wind turbine test bench foundation proposed by the present invention is implemented.

[0059] Based on the same inventive concept, the present invention further proposes a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, the safety assessment method for a wind turbine test bench foundation proposed by the present invention is implemented.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] The present invention provides a safety assessment method and system for a wind turbine test bench foundation. The method obtains the inherent parameters of the test bench foundation and the extreme operating condition parameters, operating condition parameters and seismic condition parameters throughout its entire life cycle, utilizes a pre-constructed finite element model to simulate the stress conditions of the test bench foundation during operation, obtains the ultimate load and fatigue load of the test bench foundation, and performs ultimate strength verification and fatigue strength verification on the test bench foundation based on the inherent parameters, extreme operating condition parameters, operating condition parameters, seismic condition parameters, ultimate load and fatigue load, thereby achieving an accurate assessment of the design safety of the test bench foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic flow chart of a safety assessment method for a wind turbine test bench foundation provided by the present invention;

[0063] Figure 2 A schematic cross-sectional view of a foundation for a large-scale wind turbine test bench provided in Example 1 of the present invention;

[0064] Figure 3 A schematic diagram of a safety assessment process for a test bench foundation provided in Example 1 of the present invention;

[0065] Figure 4 Schematic diagram of the SN curve of the steel bars of the test bench foundation provided in Example 1 of the present invention;

[0066] Figure 5 A schematic diagram of four safety check positions of the anchoring device of the test bench foundation provided in Example 1 of the present invention;

[0067] Figure numerals: 1. pile leg; 2. pile foundation cap; 3. supporting structure; 4. anchoring device. DETAILED DESCRIPTION

[0068] In order to better understand the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0069] Example 1:

[0070] A large wind turbine test bench foundation, such as Figure 2 As shown, it mainly consists of pile legs 1, pile cap 2, support structure 3, and anchoring device 4. External load is finally transmitted to pile legs 1 through anchoring device 4 and pile cap 2.

[0071] This embodiment provides a safety assessment method for a wind turbine test bench foundation, which performs a safety assessment on the design structure of the test bench foundation. Figure 1 As shown, the safety assessment method includes:

[0072] Step 1: Obtain the inherent parameters of the test bench foundation and the extreme working condition parameters, operating condition parameters and earthquake working condition parameters throughout its life cycle;

[0073] Step 2: Substitute the extreme working condition parameters, operating condition parameters, and earthquake condition parameters into the pre-built finite element model respectively, use the finite element model to simulate the stress of the test bench foundation, and obtain the ultimate load and fatigue load of the test bench foundation;

[0074] Step 3: Perform ultimate strength and fatigue strength checks on the test bench foundation based on inherent parameters, extreme operating condition parameters, operating condition parameters, earthquake condition parameters, ultimate loads, and fatigue loads;

[0075] Among them, the inherent parameters include the soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation.

[0076] This safety assessment method can be used to conduct safety assessments on the design of large-scale test bench foundations, and to more comprehensively and accurately evaluate the safety performance of the test bench foundation throughout its life cycle. It can also be used to evaluate the maximum testing capacity of an already built test bench.

[0077] The following is the specific implementation process of this safety assessment method.

[0078] Before step 1, a finite element model of the test bench foundation is first established.

[0079] The pile cap 2 and the upper supporting structure 3 are simulated using 4-node shell elements. The pile leg 1 is simulated using beam elements. Boundary conditions: Springs are arranged along the direction of the pile leg 1, and the horizontal stiffness coefficient, vertical stiffness coefficient and rotational stiffness coefficient (K h , K v , K θ ).

[0080] The calculation formula for the horizontal stiffness coefficient along the length of the pile is:

[0081]

[0082] Where K h is the horizontal stiffness coefficient, L is the buried depth of the pile leg, E is the elastic modulus, I is the section moment of inertia, EI is the bending stiffness, and T is the elastic length.

[0083] For sandy geology, the elastic length calculation formula is:

[0084]

[0085] Where T is the elastic length, EI is the bending stiffness, n h It is a geological coefficient, which is determined according to the looseness of the soil (the tighter the soil, the larger the value), and takes a value of 1-20.

[0086] For clay geology, the elastic length is calculated as:

[0087]

[0088] Where T is the elastic length, EI is the bending stiffness, s u It is the undrained shear strength.

[0089] The calculation formula for the equivalent length of the pile leg is:

[0090]

[0091] Where, L eq is the equivalent length of the pile leg, L is the buried depth of the pile leg, and T is the elastic length.

[0092] The calculation formula of the section moment of inertia I is:

[0093]

[0094] Where D is the diameter of the pile leg

[0095] The calculation formula of the vertical stiffness coefficient of the pile tip is:

[0096]

[0097] Where K vis the vertical stiffness coefficient of the pile tip, N p is the vertical compressive load borne by the pile, s is the settlement value of the pile under the vertical compressive load, Q h is the settlement load, L c To calculate the length (equal to the equivalent length of the pile leg minus 1 / 3 of the pile leg burial depth), D is the diameter of the pile leg, A is the net cross-sectional area of ​​the pile, and E is the elastic modulus.

[0098] Rotational stiffness coefficient K θ The calculation formula is:

[0099]

[0100] Among them, K θ is the rotational stiffness coefficient, L is the buried depth of the pile leg, T is the elastic length, EI is the bending stiffness, E is the elastic modulus, and I is the section moment of inertia.

[0101] Step 1: First, determine all possible operating conditions that may occur during the entire life cycle of the wind turbine test bench, including extreme operating conditions, various operating conditions and earthquake conditions. The operating condition simulation should take into account the deadweight, various possible force and torque combinations, and partial safety factors. If there is a rotating structure, the torque needs to be considered; if there is a hydraulic loading mechanism, the hydraulic load needs to be considered, etc., and the operating parameters of the test bench foundation for various operating conditions, such as load type, load value and number of operations, should be clarified. Figure 3 As shown in the figure, extreme working conditions are used for checking the ultimate strength of large components, and operating conditions are used for checking the fatigue strength of large components.

[0102] Step 2: Substitute the extreme working condition parameters, operating working condition parameters and earthquake working condition parameters into the pre-built finite element model respectively, use the finite element model to simulate the stress of the test bench foundation, and obtain the ultimate load and fatigue load of the test bench foundation. The ultimate load includes the maximum axial tensile load and the maximum axial compressive load of the pile leg 1, and the fatigue load includes the maximum compressive stress and the minimum compressive stress of the concrete in the steel-concrete part and the maximum tensile stress and the minimum tensile stress of the steel bar, the steel-concrete part such as the pile foundation cap 2 and the supporting structure 3, and the position III (concrete cone failure) and position IV (concrete failure under the pressure of the surface steel plate) of the anchor device 4, as shown in FIG. Figure 5 Based on the inherent parameters of the test bench foundation, such as soil mechanics parameters, structural parameters and mechanical properties parameters, as well as the extreme working condition parameters, operating condition parameters, earthquake condition parameters, ultimate load and fatigue load of the test bench foundation, the ultimate strength and fatigue strength of the test bench foundation are checked.

[0103] (1) Ultimate strength verification

[0104] a. Bearing capacity check of pile leg 1

[0105] Use the maximum bearing capacity calculation formula to calculate the maximum bearing capacity of the pile legs;

[0106] According to soil mechanics parameters, the maximum bearing capacity of a single pile is calculated using the following formula:

[0107] F max =R s +R b

[0108] Where, F max is the maximum bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile tip resistance.

[0109] The calculation formula of lateral friction resistance is:

[0110]

[0111] Where fs i is the characteristic value of the ultimate friction resistance of the rock and soil around the pile in the i-th soil layer, D is the diameter of the pile leg, thk i is the thickness of the soil layer in the i-th geological profile.

[0112] The calculation formula of pile tip resistance is:

[0113]

[0114] Where, f p is the characteristic value of the ultimate end resistance of the rock and soil at the pile end of the i-th soil layer.

[0115] The maximum tensile load of a single pile F p , Maximum compression load F c Compare the pile legs with their maximum bearing capacities to determine their appropriate bearing capacities. Consider the pile group effect and reduce the bearing capacities accordingly. Use a compression bearing capacity reduction factor of 0.85 and a tension bearing capacity reduction factor of 0.7.

[0116] The calculation formula for the reduced maximum tensile bearing capacity is:

[0117] F a =(R s +R b )×m,

[0118] Where, F a is the maximum tensile bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile tip resistance, m is the tensile bearing capacity reduction coefficient, and in this embodiment, it is selected as 0.7.

[0119] The calculation formula for the reduced maximum compressive bearing capacity is:

[0120] F a′=(R s +R b )×c,

[0121] Where, F a ′ is the maximum compression bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile tip resistance, c is the compression bearing capacity reduction coefficient, and in this embodiment, it is selected as 0.85.

[0122] If the maximum axial tensile load and the maximum axial compressive load of the pile leg 1 are respectively less than the maximum tensile bearing capacity and the maximum compressive bearing capacity, the bearing capacity of the pile leg 1 is qualified; otherwise, the bearing capacity of the pile leg 1 is unqualified.

[0123] It is also possible to calculate the maximum bending moment of a single pile under extreme working conditions based on recognized standards such as national or European standards, and check whether the reinforcement of the cross section is reasonable.

[0124] b. Ultimate strength check of pile foundation cap 2 and supporting structure 3

[0125] Finite element analysis identifies the conditions with maximum bending moment, shear force, and axial force for pile cap 2 and support structure 3. These conditions are used to perform bending moment verification to check the rationality of bending reinforcement and shear force verification to check the rationality of shear reinforcement. The partial safety factor for concrete can be 1.5, and the partial safety factor for steel can be 1.15.

[0126] c. Ultimate strength check of anchor position 4

[0127] like Figure 5 As shown, according to the actual stress characteristics, the anchoring device 4 has four key safety check positions: the bolt body at position I, the steel structure contacted by the bolt body at position II, the concrete cone at position III, and the concrete under the surface steel plate at position IV.

[0128] Finite element analysis of the test bench foundation was carried out using the finite element model of the test bench foundation. The loads of various operating conditions were simulated, and the ultimate stresses of four key safety check positions were obtained by extracting the calculation results. The ultimate strength check was performed according to the following formula:

[0129] σ=F / S≤σ s

[0130] Where, σ is the ultimate stress at the safety check position, F is the ultimate load at the safety check position, S is the effective action area at the safety check position, and σ s is the yield limit.

[0131] (2) Fatigue strength verification

[0132] a. Fatigue strength check of steel-concrete parts

[0133] The pile foundation cap 2 and the supporting structure 3 are both steel-concrete structures, and the maximum number of loads that the concrete and steel bars can withstand under alternating stress is checked respectively.

[0134] Use the finite element model to carry out finite element analysis, find the working conditions corresponding to the maximum stress range of the cross section in all operating conditions, and extract the maximum compressive stress σ of the concrete c，max , minimum compressive stress σ c，min , maximum tensile stress of steel bar σ s，max , minimum tensile stress of steel bar σ s，min This operating condition is considered to be the only operating condition in the entire service life. At this time, the alternating stress range of concrete is determined by the following formula:

[0135] σ c，range =σ c，max -σ c，min

[0136] Where σ c，range is the alternating stress range of concrete, σ c，max is the maximum compressive stress of concrete, σ c，min is the minimum compressive stress of concrete.

[0137] 1) Concrete

[0138] Concrete in the alternating stress range σ c，range The maximum load times that can be sustained are determined by the following formula:

[0139]

[0140] Where N1 is the maximum load times of concrete, E cd，max is the maximum compressive stress level, R i is the ratio of the minimum compressive stress level to the maximum compressive stress level.

[0141] The maximum compressive stress level is calculated by the following formula:

[0142]

[0143] Where, E cd，max is the maximum compressive stress level of concrete, σ c，max is the maximum compressive stress of concrete, f cd，fat Design for fatigue strength of concrete.

[0144] The minimum compressive stress level is calculated by the following formula:

[0145]

[0146] Where, E cd，min is the minimum compressive stress level of concrete, σ c，minis the minimum compressive stress of concrete, f cd，fat Design for fatigue strength of concrete.

[0147] The stress ratio is calculated by the following formula:

[0148]

[0149] Where R i is the stress ratio, E cd，min is the minimum compressive stress level, E cd，max is the maximum compressive stress level.

[0150] The design fatigue strength of concrete is calculated by the following formula:

[0151]

[0152] Where, f cd，fat is the design fatigue strength of concrete, f ck is the standard value of concrete axial compressive strength, obtained from geological survey and geotechnical tests, k is the concrete strength reduction coefficient that depends on the concrete age, β cc is a coefficient that depends on the age of concrete, γ c It is the partial safety factor of concrete (1.5 for permanent and temporary loads, 1.2 for accidental loads).

[0153] The criterion for judging concrete safety is that the ratio of the actual number of loadings to the maximum number of loadings N must be less than 1. The actual number of loadings can be proposed by the wind turbine manufacturer based on scenarios tested during the wind turbine drive train or the entire life cycle of the blades.

[0154] 2) Steel bars

[0155] Common SN curves of straight and bent steel bars (except welded and hinged) are as follows: Figure 4 As shown, the curve formula is:

[0156]

[0157] Where: Δσ is the amplitude of the alternating stress of the steel bar, N is the maximum load times that the steel bar can withstand under the stress range, k1 and k2 are logN on the SN curve of the steel bar * The slopes of the curves on both sides of the corresponding position are k1=5; k2=9, N * =10 6 , Δσ Rsk N * Corresponding alternating stress amplitude, N * The corresponding Δσ Rsk =162.5Mpa.

[0158] The amplitude of the alternating stress of the steel bar Δσ is determined by the following formula:

[0159] Δσ=σ s，range =σ s，max -σ s，min

[0160] Where σ s，range is the alternating stress range of steel bars, σ s，max is the maximum tensile stress of the steel bar, σ s，min is the minimum tensile stress of the steel bar.

[0161] Steel bars in the alternating stress range σ s，range The maximum load times N that can be sustained can be determined by the above curve formula.

[0162] The safety criterion for steel reinforcement is that the ratio of the actual number of loadings to the maximum number of loadings N must be less than 1. The actual number of loadings can be proposed by the wind turbine manufacturer based on scenarios tested during the wind turbine drive train or the entire life cycle of the blades.

[0163] c. Anchoring device

[0164] like Figure 5 As shown in Figure 1, the anchor device 4 has four key safety check positions. By conducting finite element analysis and simulating the loads of various operating conditions of the test bench, the stress ranges of the four key safety check positions were extracted and calculated. Positions I and II were checked according to the verification method commonly used in European or national standards. The failure mode of position III is failure of the concrete cone surface, and the failure mode of position IV is failure of the concrete under pressure of the surface steel plate. Therefore, the fatigue strength verification of positions III and IV was carried out according to the fatigue strength verification of the steel-concrete part in (2)a.

[0165] (3) Stiffness verification

[0166] If the test bench has a dynamic loading device (for example, a drive chain test bench has a motor drive device or a hydraulic loading mechanism, and a blade test bench has a hydraulic loading mechanism), a vibration analysis is required. The finite element model of the test bench foundation is used to perform modal calculations on the test bench foundation to obtain the modal frequencies of the test bench and avoid the rotation frequency range of the rotating parts.

[0167] This safety assessment method is suitable for the safety assessment of large-scale wind turbine test rig foundations. Based on the test rig foundation's inherent parameters and various operating condition parameters, a finite element model is used to determine the ultimate and fatigue loads of each component. Appropriate verification methods are then used to perform ultimate and fatigue strength verification on components such as the pile legs 1, pile cap 2, support structure 3, and anchoring device 4. Furthermore, overall vibration analysis and stiffness assessment of the test rig foundation are performed based on actual operating conditions, thereby achieving a comprehensive safety assessment of the test rig foundation. This safety assessment method can serve as a guiding approach for safety reviews of test rig foundations.

[0168] Example 2:

[0169] This embodiment provides a safety assessment system for a wind turbine test bench foundation, the safety assessment system comprising:

[0170] Acquisition module, used to obtain the inherent parameters of the test bench foundation and the extreme working condition parameters, operating condition parameters and earthquake condition parameters throughout the entire life cycle;

[0171] The simulation module is used to substitute extreme working condition parameters, operating condition parameters, and earthquake condition parameters into the pre-built finite element model, and use the finite element model to simulate the stress of the test bench foundation to obtain the ultimate load and fatigue load of the test bench foundation;

[0172] The verification module is used to verify the ultimate strength and fatigue strength of the test bench foundation based on inherent parameters, extreme operating parameters, operating parameters, earthquake parameters, ultimate loads, and fatigue loads;

[0173] Among them, the inherent parameters include the soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation.

[0174] The verification module includes:

[0175] The ultimate strength verification unit is used to verify the bearing capacity of the pile legs based on the maximum axial tensile load and maximum axial compressive load of the pile legs;

[0176] The fatigue strength verification unit is used to perform fatigue strength verification on the steel-concrete part of the test bench foundation based on the maximum and minimum compressive stresses of the concrete and the maximum and minimum tensile stresses of the steel bars. The steel-concrete part includes the pile cap, anchoring device and the supporting structure above the pile cap.

[0177] The safety assessment system also includes a stiffness verification module for performing modal calculations on the test bench foundation using a finite element model to obtain the modal frequency of the test bench foundation, and comparing the modal frequency with the rotational frequency range of the wind turbine to be tested to verify the stiffness of the test bench foundation.

[0178] The safety assessment system also includes a finite element modeling module, which is used to establish a finite element model of the pile foundation cap and the supporting structure using shell elements, establish a finite element model of the pile legs using beam elements, set boundary conditions for the pile leg finite element model, and construct a finite element model of the test bench foundation based on the finite element models and boundary conditions of the above components.

[0179] Example 3:

[0180] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer memory. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a computer storage medium to implement a corresponding method flow or corresponding function, so as to implement the steps of a safety assessment method for a wind turbine test bench foundation in the above-mentioned embodiment 1.

[0181] Example 4:

[0182] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of a safety assessment method for a wind turbine test bench foundation in the above-mentioned embodiment 1.

[0183] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0184] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0185] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0186] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0187] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A safety assessment method for a wind turbine test bench foundation, characterized in that: The safety assessment method includes: Obtaining inherent parameters of the test bench foundation and extreme operating condition parameters, operating condition parameters, and seismic condition parameters throughout its life cycle; Substituting the extreme working condition parameters, operating working condition parameters and earthquake working condition parameters into a pre-built finite element model respectively, using the finite element model to perform a stress simulation on the test bench foundation to obtain the ultimate load and fatigue load of the test bench foundation; Performing an ultimate strength check and a fatigue strength check on the test bench foundation based on the inherent parameters, extreme operating condition parameters, operating condition parameters, earthquake operating condition parameters, ultimate loads, and fatigue loads includes: Checking the bearing capacity of the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs; Fatigue strength verification is performed on the steel-concrete portion of the test bench foundation based on the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar, wherein the steel-concrete portion includes the pile foundation cap, the supporting structure on the upper portion of the pile foundation cap, and the anchoring device inside the pile foundation cap; Among them, the inherent parameters include the soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation, the ultimate load includes the maximum axial tensile load and maximum axial compressive load of the pile leg, and the fatigue load includes the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar.

2. The security assessment method according to claim 1, wherein: The checking of the bearing capacity of the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs comprises: The maximum tensile bearing capacity and the maximum compressive bearing capacity of the pile leg are calculated based on the soil mechanics parameters and the maximum tensile bearing capacity calculation formula and the maximum compressive bearing capacity calculation formula; The maximum axial tensile load and the maximum axial compressive load are compared with the maximum tensile bearing capacity and the maximum compressive bearing capacity respectively. If the maximum axial tensile load and the maximum axial compressive load are respectively less than the maximum tensile bearing capacity and the maximum compressive bearing capacity, the bearing capacity of the pile leg is qualified; otherwise, the bearing capacity of the pile leg is unqualified.

3. The security assessment method according to claim 2, wherein: The maximum tensile bearing capacity calculation formula is as follows: Where, F a is the maximum tensile bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile end resistance, m is the tensile bearing capacity reduction factor, fs i is the characteristic value of the ultimate friction resistance of the rock and soil around the pile in the i-th soil layer, f p is the ultimate end resistance characteristic value of the rock and soil at the pile end of the i-th soil layer, thk i is the thickness of the soil layer in the ith geological profile, D is the diameter of the pile leg, and n is the total number of soil layers in the geological profile.

4. The security assessment method according to claim 2, wherein: The maximum compressive bearing capacity calculation formula is as follows: Where, F a ′ is the maximum compressive bearing capacity of a single pile, R s is the lateral friction resistance, R b is the pile tip resistance, c is the compression bearing capacity reduction factor, fs i is the characteristic value of the ultimate friction resistance of the rock and soil around the pile in the i-th soil layer, f p is the ultimate end resistance characteristic value of the rock and soil at the pile end of the i-th soil layer, thk i is the thickness of the soil layer in the ith geological profile, D is the diameter of the pile leg, and n is the total number of soil layers in the geological profile.

5. The security assessment method according to claim 1, wherein: The fatigue strength check of the steel-concrete part of the test bench foundation based on the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar includes: The maximum number of loads that concrete can withstand under alternating stress is calculated based on the maximum compressive stress and minimum compressive stress of concrete combined with the formula for calculating the maximum number of loads of concrete. The maximum number of loads that steel bars can withstand under alternating stress is calculated based on the maximum and minimum tensile stress of steel bars combined with the SN curve formula of steel bars. If the ratio of the actual loading times of concrete to the maximum loading times that concrete can withstand, and the ratio of the actual loading times of steel bars to the maximum loading times that steel bars can withstand are both less than 1, then the fatigue strength of the steel-concrete structure is qualified; otherwise, the fatigue strength of the steel-concrete structure is unqualified.

6. The security assessment method according to claim 5, wherein: The calculation formula for the maximum load times of concrete is as follows: Where N1 is the maximum load times that concrete can withstand under alternating stress, E cd，max is the maximum compressive stress level of concrete, R i is the stress ratio of concrete.

7. The security assessment method according to claim 5, wherein: The curve formula is shown below: Where Δσ is the amplitude of the alternating stress, N is the maximum number of loads that the steel bar can withstand under the alternating stress, and N* is 10 6 , k1 and k2 are the slopes of the curves on both sides of the corresponding position of logN* on the SN curve of the steel bar.

8. The security assessment method according to claim 1, wherein: The safety assessment method further includes: Performing modal calculation on the test bench foundation using the finite element model to obtain the modal frequency of the test bench foundation; The modal frequency is compared with the rotation frequency range of the wind turbine to be tested. If the modal frequency falls within the rotation frequency range, the stiffness of the test bench foundation is unqualified; otherwise, the stiffness of the test bench foundation is qualified.

9. The security assessment method according to claim 1, wherein: The safety assessment method further includes: Using shell elements to establish finite element models of the pile foundation cap and the supporting structure, and using beam elements to establish a finite element model of the pile legs; Setting boundary conditions for the finite element model of the pile leg, wherein the boundary conditions include a horizontal stiffness coefficient, a vertical stiffness coefficient, and a rotational stiffness coefficient; A finite element model of the test bench foundation is constructed based on the finite element models of the pile foundation cap and the supporting structure, the finite element model of the pile legs, and the boundary conditions.

10. The security assessment method according to claim 9, wherein: The setting of boundary conditions for the finite element model of the pile leg includes: The horizontal stiffness coefficient, vertical stiffness coefficient and rotational stiffness coefficient are set based on the structural parameters and mechanical performance parameters of the pile leg in combination with the horizontal stiffness coefficient formula, the pile end vertical stiffness coefficient formula and the rotational stiffness coefficient formula.

11. The security assessment method according to claim 10, wherein: The horizontal stiffness coefficient is shown in the following formula: Among them, K h is the horizontal stiffness coefficient arranged along the pile length, L is the buried depth of the pile leg, T is the elastic length, EI is the bending stiffness, E is the elastic modulus, and I is the section moment of inertia.

12. The security assessment method according to claim 10, wherein: The vertical stiffness coefficient of the pile tip is as follows: Among them, K v is the vertical stiffness coefficient of the pile tip, N p is the vertical compressive load borne by the pile, s is the settlement value of the pile under the vertical compressive load, Q h is the settlement load, L c To calculate the length, D is the diameter of the pile leg, A is the net cross-sectional area of ​​the pile, and E is the elastic modulus.

13. The security assessment method according to claim 10, wherein: The rotational stiffness coefficient is shown in the following formula: Among them, K θ is the rotational stiffness coefficient, L is the buried depth of the pile leg, T is the elastic length, EI is the bending stiffness, E is the elastic modulus, and I is the section moment of inertia.

14. The security assessment method according to claim 9, wherein: The shell element has 4 nodes.

15. A safety assessment system for a wind turbine test bench foundation, characterized in that: The safety assessment system includes: An acquisition module, used to obtain the inherent parameters of the test bench foundation and the extreme working condition parameters, operating condition parameters and earthquake working condition parameters throughout the entire life cycle; a simulation module, configured to substitute the extreme working condition parameters, the operating working condition parameters, and the earthquake working condition parameters into a pre-built finite element model, perform a stress simulation on the test bench foundation using the finite element model, and obtain the ultimate load and fatigue load of the test bench foundation; A verification module is used to perform ultimate strength verification and fatigue strength verification on the test bench foundation based on the inherent parameters, extreme operating condition parameters, operating condition parameters, earthquake condition parameters, ultimate loads, and fatigue loads, including: An ultimate strength checking unit, configured to check the bearing capacity of the pile legs based on the maximum axial tensile load and the maximum axial compressive load of the pile legs; a fatigue strength verification unit for performing fatigue strength verification on the steel-concrete portion of the test bench foundation based on the maximum compressive stress and minimum compressive stress of the concrete and the maximum tensile stress and minimum tensile stress of the steel bar, the steel-concrete portion including the pile foundation cap, the anchoring device, and the supporting structure above the pile foundation cap; The inherent parameters include soil mechanics parameters, structural parameters and mechanical performance parameters of the test bench foundation.

16. A computer device, characterized in that: include: one or more processors; The processor is configured to store one or more programs; When the one or more programs are executed by the one or more processors, a safety assessment method for a wind turbine test bench foundation according to any one of claims 1 to 14 is implemented.

17. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, a safety assessment method for a wind turbine test bench foundation according to any one of claims 1 to 14 is implemented.

Images