Simulation calculation method for seismic dynamic response of three-barrel foundation of offshore wind turbine in sand soil layer

Abstract

The invention discloses a method for simulating and calculating earthquake dynamic response of an offshore wind turbine three-barrel foundation in a sand soil layer, and relates to the technical field of offshore wind turbine structure dynamic response testing. Comprising the following steps: acquiring construction data, preprocessing the construction data to generate an initial data set, establishing a three-dimensional digital model of a soil body, carrying out initial crustal stress balance, obtaining an initial crustal stress field, setting the three-dimensional digital model of the soil body as a SANISAND constitutive model, and introducing the initial crustal stress field to obtain a soil body model after secondary balance. Introducing a fan model to establish an offshore fan three-barrel foundation three-dimensional digital model, setting contact surface parameters, carrying out final balance to obtain an initial stress response model, inputting an environment load at the upper part, inputting seismic waves at the bottom, setting a free field boundary, writing an output command for the obtained model, and carrying out post-processing; and carrying out dynamic analysis on the three-barrel foundation of the offshore wind turbine. According to the method, the earthquake dynamic response of the three-barrel foundation of the offshore wind turbine in the sand foundation can be accurately and efficiently measured and calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind turbine structure dynamic response testing, and in particular to a method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer. Background Art

[0002] In recent years, offshore wind turbine suction bucket foundations have been favored by the industry due to their low cost and easy installation. Suction bucket foundations are divided into single bucket foundations and multi-bucket foundations. Multi-bucket foundations have a higher anti-overturning bearing capacity, which makes them more suitable for installation in deep water (25-50m) to support offshore wind turbines. In addition to being subjected to environmental loads such as wind and waves for a long time, offshore wind turbine systems are also threatened by seismic loads. During the operation of the wind turbine system, the requirements of the normal service limit state (SLS) that dominates its foundation design must be met.

[0003] Unlike single-barrel foundations, multi-barrel foundations resist overturning moments through the vertical compression-pulling behavior of a single barrel. Many offshore wind turbines at home and abroad are installed in earthquake-prone areas. Sandy soil foundations are prone to liquefaction under strong earthquakes, causing excessive settlement or angular displacement of the offshore wind turbine foundation installed in the sand, affecting the normal operation of the upper wind turbine structure, and even causing the overturning and destruction of the entire wind turbine.

[0004] How to effectively calculate the seismic dynamic response of the three-barrel foundation of offshore wind turbines in sand foundation, including the displacement and rotation of the three-barrel foundation under earthquake action and the liquefaction of the soil around the foundation, is crucial to the seismic design of the three-barrel foundation of offshore wind turbines.

[0005] Therefore, it is an urgent problem for technical personnel in this field to propose a simulation and measurement method for the seismic dynamic response of the three-barrel foundation of an offshore wind turbine in a sandy soil layer to solve the problem that the existing technology cannot calculate the seismic dynamic response of the three-barrel foundation of an offshore wind turbine in a sandy soil foundation. Summary of the invention

[0006] In view of this, the present invention provides a simulation and measurement method for the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sandy soil layer, which can accurately and efficiently calculate the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sandy soil foundation.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer comprises the following steps:

[0009] Data acquisition step: obtain construction data and preprocess the construction data to generate an initial data set;

[0010] Model construction steps: Use the initial data set to build a wind turbine model and a three-dimensional soil digital model, perform initial geostress balance, and obtain the initial geostress field;

[0011] Soil setting steps: Set the three-dimensional digital model of the soil as the SANISAND constitutive model, introduce the initial geostress field into the SANISAND constitutive model for secondary balance, and obtain the soil model after secondary balance;

[0012] Model generation steps: introduce the wind turbine model into the soil model after secondary balance, establish a three-dimensional digital model of the offshore wind turbine three-barrel foundation, set the contact surface parameters, and perform final balance to obtain the initial stress response model;

[0013] Load application steps: input wind and wave environmental loads to the upper part of the initial stress response model, input seismic waves to the bottom, and set the free field boundary to obtain the set stress response model;

[0014] Output analysis steps: Write output commands for post-processing and perform dynamic analysis of the three-barrel foundation of an offshore wind turbine.

[0015] In the above method, optionally, in the data acquisition step, data preprocessing includes adjusting correction parameters using triaxial tests combined with construction data.

[0016] In the above method, optionally, in the model building step, a linear elastic model is used to perform initial geostress balance on the three-dimensional digital model of the soil.

[0017] In the above method, optionally, after each ground stress equilibrium is completed, the initial displacement and velocity of the unit node are set to 0.

[0018] In the above method, optionally, in the model generation step, the part where the wind turbine model contacts the soil model after secondary equilibrium is used as the contact surface, and the parameters defining the contact surface include normal stiffness and shear stiffness. The normal stiffness k n and shear stiffness k s The expression is as follows:

[0019]

[0020] Among them, k n is the normal stiffness, k s is the tangential stiffness, K is the bulk modulus, G is the shear modulus, ΔZ min is the minimum size of the mesh on the normal connection area of ​​the contact surface.

[0021] In the above method, optionally, in the load application step, the seismic waves are filtered and baseline corrected.

[0022] It can be seen from the above technical scheme that compared with the prior art, the present invention provides a simulation and measurement method for the seismic dynamic response of the three-barrel foundation of an offshore wind turbine in a sand layer, which can more accurately analyze the displacement, stress of the three-barrel foundation of an offshore wind turbine and the liquefaction of the soil around the foundation, thereby achieving the purpose of saving calculation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 It is a flow chart of a method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer disclosed in the present invention;

[0025] Figure 2 A three-dimensional digital model diagram of the three-barrel foundation of an offshore wind turbine disclosed in the present invention;

[0026] Figure 3 It is the vertical effective stress diagram of the soil after the initial ground stress is balanced disclosed by the present invention;

[0027] Figure 4 It is a cross-sectional view of the bucket-soil contact surface disclosed in the present invention;

[0028] Figure 5a A time history diagram of simulated random wind load disclosed in an embodiment of the present invention;

[0029] Figure 5b A time history diagram of simulated random wave load disclosed in an embodiment of the present invention;

[0030] Figure 6a It is a pore pressure cross-section cloud diagram at the right barrel position in the three-barrel foundation disclosed in an embodiment of the present invention;

[0031] Figure 6b It is a pore pressure cross-section cloud diagram at the position of the left barrel in the three-barrel foundation disclosed in an embodiment of the present invention;

[0032] Figure 7a It is a displacement cross-sectional cloud diagram at the right barrel position in the three-barrel foundation disclosed in an embodiment of the present invention;

[0033] Figure 7b This is a displacement cross-sectional cloud diagram at the position of the left barrel in the three-barrel foundation disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0036] Reference Figure 1 As shown, the present invention discloses a method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer, comprising the following steps:

[0037] Data acquisition step: obtain construction data and preprocess the construction data to generate an initial data set;

[0038] Model construction steps: Use the initial data set to build a wind turbine model and a three-dimensional soil digital model, perform initial geostress balance, and obtain the initial geostress field;

[0039] Soil setting steps: Set the three-dimensional digital model of the soil as the SANISAND constitutive model, introduce the initial geostress field into the SANISAND constitutive model for secondary balance, and obtain the soil model after secondary balance;

[0040] Model generation steps: introduce the wind turbine model into the soil model after secondary balance, establish a three-dimensional digital model of the offshore wind turbine three-barrel foundation, set the contact surface parameters, and perform final balance to obtain the initial stress response model;

[0041] Load application steps: input wind and wave environmental loads to the upper part of the initial stress response model, input seismic waves to the bottom, and set the free field boundary to obtain the set stress response model;

[0042] Output analysis steps: Write output commands for post-processing and perform dynamic analysis of the three-barrel foundation of an offshore wind turbine.

[0043] Furthermore, in the data acquisition step, data preprocessing includes adjusting correction parameters using triaxial tests combined with construction data.

[0044] Furthermore, in the data acquisition step, the initial data set includes SANISAND constitutive model parameters, model dimensions, model material parameters, and the like.

[0045] Specifically, monotonic / cyclic drainage / undrained triaxial tests were carried out on the soil at the actual construction site, and combined with the triaxial test numerical simulation, the parameters of the SANISAND constitutive model were adjusted and corrected, and the size and material parameters of the offshore wind turbines were determined.

[0046] Furthermore, in the model building step, since it is difficult to build a three-dimensional digital model in FLAC 3D, ABAQUS, Rhino and other software are used to build the three-dimensional digital model. Figure 2 As shown in the figure, when using the finite element software ABAQUS to model the offshore wind turbine and soil, the "Tools"-"Set" function is used to group and name the offshore wind turbine, foundation, and soil parts, and the overall model is meshed. The minimum mesh size is calculated according to the following formula:

[0047]

[0048] Among them, λ is the wavelength corresponding to the maximum frequency. The models of soil and offshore wind turbine are exported as “.inp” files respectively.

[0049] Specifically, when modeling the wind turbine superstructure, the wind turbine tower needs to be segmented and cut at the locations where environmental loads such as wind and waves are applied.

[0050] Furthermore, the file in “.inp” format was imported into FLAC 3D, and the linear elastic model was used to perform initial geostress equilibrium on the three-dimensional digital model of the soil.

[0051] Specifically, the parameters used in the linear elastic model are consistent with those used in the SANISAND constitutive model.

[0052] Furthermore, the initial geostress balance sets the corresponding initial pore water pressure according to the required sea level height, and applies corresponding force to the ground to simulate the gravity of seawater. The specific method is: first import the soil part into FLAC 3D software, assign the soil an "elastic" constitutive model, and set the corresponding soil parameters; determine the water depth, assign the seawater an "isotropic" constitutive model, set the fluid density to 1, and set the initial pore water pressure field; set boundary conditions, fix the horizontal displacement of the boundaries around the model and the vertical displacement of the bottom of the model; finally, apply gravity to the model, set the equilibrium conditions, and perform equilibrium calculations to obtain the equilibrium results as shown in Figure 2. Figure 3 shown.

[0053] Furthermore, after each in-situ stress equilibrium is completed, the initial displacement and velocity of the unit node are set to 0.

[0054] Furthermore, in the soil setting step, the displacement and velocity generated by the initial geostress equilibrium are cleared, the soil is set to the "dafalias" constitutive model, that is, the SANISAND constitutive model, and the soil is assigned corresponding soil parameters. The initial stress field is defined by the following command:

[0055] fish define ini_stress

[0056] loop foreach local zp_zone.list

[0057] ifzone.model(zp_)='dafalias'

[0058] local pp0 = zone.pp(zp_)

[0059] zone.prop(zp_,'sxx-ini')=zone.stress.xx(zp_)+pp

[0060] zone.prop(zp_,'syy-ini')=zone.stress.yy(zp_)+pp

[0061] zone.prop(zp_,'szz-ini')=zone.stress.zz(zp_)+pp

[0062] zone.prop(zp_,'sxy-ini')=zone.stress.xy(zp_)

[0063] zone.prop(zp_,'sxz-ini')=zone.stress.xz(zp_)

[0064] zone.prop(zp_,'syz-ini')=zone.stress.yz(zp_)

[0065] endif

[0066] endloop

[0067] end

[0068] @ini_stress

[0069] Apply initial geostress to the soil, set it up, select appropriate equilibrium conditions, and perform secondary equilibrium.

[0070] Furthermore, in the model generation step, the part where the wind turbine model contacts the soil model after secondary equilibrium is used as the contact surface. The parameters defining the contact surface include normal stiffness and shear stiffness. The normal stiffness k n and shear stiffness k s The expression is as follows:

[0071]

[0072] Among them, k n is the normal stiffness, k s is the tangential stiffness, K is the bulk modulus, G is the shear modulus, ΔZ min is the minimum size of the mesh on the normal connection area of ​​the contact surface.

[0073] Specifically, Figure 4 As shown, the displacement and velocity generated during the secondary balance are cleared, the offshore wind turbine model is imported into FLAC 3D, and the overlapping part of the soil and the offshore wind turbine foundation is deleted. The wind turbine and the foundation are moved up, and the model is divided into surfaces using the "zoneface skin" command to obtain the contact surface. Since there is no operation on the superstructure, for better display, only the half model of the foundation, soil and bucket-soil contact surface is shown here. When calculating, K and G both use the value of the larger stiffness in the unit adjacent to the contact surface; the contact surface is set to an impermeable boundary, and the "attach" command is used to connect the wind turbine segments. This connection method will treat different segments as the same object, and the offshore wind turbine is moved down to the correct position for final stress balance.

[0074] Further, in the load application step, refer to Figure 5a and Figure 5b As shown, select appropriate wind and wave loads. Open the free field boundary and input the corresponding damping. You can choose local damping or Ruili damping here. Filter and baseline correction are performed on the seismic waves. Filtering and baseline correction can be performed through software such as OriginPro and SeismoSignal, or using the FISH function FFT.fis provided by FLAC 3D. The filtering operation is to filter out the high-frequency part of the seismic wave to reduce the impact of high-frequency noise on the numerical simulation results. This method can also reduce the maximum frequency of the seismic wave, thereby increasing the minimum grid required for calculation and reducing the number of units, which can save calculation time. Baseline correction is to add a low-frequency waveform to the original acceleration time history, which can prevent residual displacement and velocity at the bottom of the model at the end of the dynamic calculation. Use the following command to load the seismic wave to the bottom of the model:

[0075] table'acc-x'import'Seismic Load.txt'

[0076] zone gridpoint free velocity-x rangeposition-z ab

[0077] zone face apply acc-x 9.8table'acc-x'range position-z ab

[0078] The wind and wave loads are then applied as uniform loads to the contact surface established using the "attach" command. The "history interval" command is used to set the historical interval for data recording.

[0079] Furthermore, in the output analysis step, use the "history" command to output the required data. If parameters not mentioned in the manual are involved, you can output them by writing a fish function. Set the operation time for dynamic analysis and post-process the output data.

[0080] The implementation results of the present invention are as follows Figure 6a , Figure 6b , Figure 7a and Figure 7b As shown, it is not difficult to conclude that the three-bucket foundation can improve the soil's ability to resist liquefaction, and the pore pressure inside the suction bucket is significantly greater than the pore pressure outside the suction bucket; the three-bucket foundation obviously rotates in the positive direction of the x-axis.

[0081] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0082] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A simulation method for calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sandy soil layer. It is characterized in that The following steps are involved: Data acquisition step: obtain construction data and preprocess the construction data to generate an initial data set; Model construction steps: Use the initial data set to build a wind turbine model and a three-dimensional soil digital model, perform initial geostress balance, and obtain the initial geostress field; Soil setting steps: Set the three-dimensional digital model of the soil as the SANISAND constitutive model, introduce the initial geostress field into the SANISAND constitutive model for secondary balance, and obtain the soil model after secondary balance; Model generation steps: introduce the wind turbine model into the soil model after secondary balance, establish a three-dimensional digital model of the offshore wind turbine three-barrel foundation, set the contact surface parameters, and perform final balance to obtain the initial stress response model; Load application steps: input wind and wave environmental loads to the upper part of the initial stress response model, input seismic waves to the bottom, and set the free field boundary to obtain the set stress response model; Output analysis steps: Write output commands for post-processing and perform dynamic analysis of the three-barrel foundation of an offshore wind turbine.

2. According to the method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer in claim 1, It is characterized in that In the data acquisition step, data preprocessing includes adjusting and correcting parameters using triaxial tests combined with construction data.

3. According to the method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer in claim 1, It is characterized in that In the model building step, the linear elastic model is used to perform initial geostress balance on the three-dimensional digital model of the soil.

4. According to the method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer in claim 3, It is characterized in that After each ground stress equilibrium is completed, the initial displacement and velocity of the unit node are set to 0.

5. According to the method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer in claim 1, It is characterized in that In the model generation step, the part where the wind turbine model contacts the soil model after secondary equilibrium is used as the contact surface. The parameters defining the contact surface include normal stiffness and shear stiffness. The normal stiffness k n and shear stiffness k s The expression is as follows: Among them, k n is the normal stiffness, k s is the tangential stiffness, K is the bulk modulus, G is the shear modulus, ΔZ min is the minimum size of the mesh on the normal connection area of ​​the contact surface.

6. According to the method for simulating and calculating the seismic dynamic response of a three-barrel foundation of an offshore wind turbine in a sand layer in claim 1, It is characterized in that During the load application step, the seismic waves are filtered and baseline corrected.

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