Offshore single-pile foundation layered soil body scouring effect calculation method and device, storage medium and equipment

Abstract

The invention discloses an offshore single-pile foundation layered soil body scouring effect calculation method and device, a storage medium and equipment. The method comprises the steps that S1, the size, soil layer distribution and mechanical parameters of a single-pile foundation are determined; s2, constructing a plurality of calculation points in the depth direction and determining vertical stress; s3, determining the scour depth, the scoured soil layer and calculation point information; s4, assuming that the effective weight of the point is calculated after scouring, and determining a vertical stress expression; s5, solving the mechanical parameters of the first calculation point after scouring and updating the vertical stress expression of the lower adjacent point, and so on until the mechanical parameters of the final point after scouring are determined; s6, re-dividing the layering condition of the soil body; and determining the calculated thickness of the first soil layer after scouring, solving the equivalent thickness of the first soil layer, determining the calculated thickness of the lower adjacent soil layer, and so on until the equivalent thickness of the last soil layer is determined. According to the method, the scouring effect influence of the offshore single-pile foundation under the layered soil body condition can be accurately calculated, and a key analysis means is provided for engineering designers.

Description

Technical Field

[0001] The present application relates to the technical field of offshore wind turbine single pile foundation analysis, and in particular to a method and device for calculating the scour unloading effect of an offshore wind turbine single pile foundation under layered soil conditions. Background Art

[0002] Offshore single pile foundation has become an important part of my country's offshore wind power construction due to its advantages of low cost, simple construction and reliable structure. During the service life of the wind turbine, the wave and current action will cause erosion and stripping of the soil around the pile. At the same time, the remaining soil below will change from the normal consolidation state to the over-consolidation state due to the unloading effect. Some mechanical parameters will change, resulting in changes in the original soil stratification. This scouring unloading effect has a significant impact on the accurate analysis of pile-soil interaction.

[0003] In the related technologies, the theoretical methods are only applicable to homogeneous clay or homogeneous sand foundation conditions. In actual engineering, the marine geology is mostly complex layered soil, and the above theoretical methods cannot be directly applied. In addition, the layered soil conditions also affect the accurate calculation of pile-soil interaction, which needs to be considered in the process of building the analysis model. Therefore, it is urgent to construct a calculation method for the scour unloading effect of a single pile foundation of an offshore wind turbine that takes into account the layered soil conditions. Summary of the invention

[0004] In view of this, the present application provides a method and device for calculating the scour unloading effect of a single pile foundation of an offshore wind turbine taking into account layered soil conditions, which can accurately and conveniently calculate the influence of the scour effect under complex layered soil conditions.

[0005] In a first aspect, the present invention provides a method for calculating the scour effect of layered soil of an offshore single pile foundation, comprising the following steps:

[0006] S1. Determine the geometric dimensions of the offshore wind turbine single pile foundation, the soil layer distribution information above the pile end and the mechanical parameters;

[0007] S2, construct several calculation points along the depth direction from the mud surface before scouring to the pile end and calculate the initial vertical stress at each calculation point;

[0008] S3. Determine the scouring depth around the single pile foundation, the number of remaining soil layers after scouring, the number of calculation points and the distance between each calculation point;

[0009] S4, assuming the effective weight of each calculation point after scouring, and determining the vertical stress expression of the first calculation point after scouring based on the assumed effective weight of the calculation point after scouring;

[0010] S5. According to the calculation theory of scour unloading effect under homogeneous soil conditions, solve the mechanical parameters of the soil at the first calculation point after scour and update the vertical stress expression of the adjacent calculation point below, and so on, until the mechanical parameters of the final calculation point after scour are updated;

[0011] S6. Re-divide the soil stratification according to the distribution information of the remaining calculation points after scouring; determine the calculated thickness of the first soil layer after scouring; solve the equivalent thickness of the first soil layer after scouring and determine the calculated thickness of the adjacent soil layer below based on the calculation theory of layered soil effect and the updated mechanical parameters, and so on, until the equivalent thickness of the last soil layer is calculated.

[0012] As a preferred technical solution of the present invention: the geometric dimensions of the offshore wind turbine single pile foundation in step S1 include: single pile foundation diameter D, pile length L under the mud surface;

[0013] The soil layer distribution information and mechanical parameters above the pile end of the single pile foundation include: the total number of soil layers above the pile end m, the thickness of each soil layer H, the effective weight of each soil layer γ int ;

[0014] Among them, the mechanical parameters of clay soil layer also include: soil moisture content ω int , initial undrained shear strength Cu int , compression index C c_int , expansion index C s_int 、Effective friction angle of drainage condition φ cu_int ; The mechanical parameters of sandy soil layers also include: critical internal friction angle φ s_int , relative density Dr int , maximum porosity emax, minimum porosity emin, soil particle density Gs, uniaxial unloading coefficient C ur .

[0015] As a preferred technical solution of the present invention: in the step S2, the first calculation point along the depth direction from the mud surface before scouring to the pile end is selected at a non-mud surface position below the seabed mud surface and close to the mud surface, and the depth of the final calculation point should be consistent with the depth of the pile end of the single pile foundation; the calculation points can be evenly distributed with equal intervals, or unequal intervals.

[0016] As a preferred technical solution of the present invention: the initial vertical stress at each calculation point is:

[0017]

[0018] D i =(0…1…0)

[0019] In the formula, σ 1int_i is the initial vertical stress at calculation point i before scouring, D i is a 1×m row vector, where the kth column element is 1 and the other position elements are all 0, k is the soil layer number where the calculation point i is located, k∈[1,m]; γ int_1 is the effective weight of soil layer 1 before scouring, γ int_2 is the effective weight of soil layer 2 before scouring, γint_m is the effective weight of soil layer m before scouring; H1 is the thickness of soil layer 1 before scouring, H2 is the thickness of soil layer 2 before scouring, H m-1 is the thickness of the soil layer m-1 before scouring; Z int_i is the depth of calculation point i before scouring, and m is the number of soil layers.

[0020] As a preferred technical solution of the present invention: in step S4, the vertical stress at the first calculation point is determined based on the assumed effective weight after scouring as:

[0021] σ 1sc_1 =(Δh1Δh2…Δh nsc )R'1

[0022] R'1=(γ' sc_1 0…0) T

[0023] In the formula, σ 1sc_1 is the vertical stress at calculation point 1 after scouring, Δh1 is the distance below the mud surface of the first calculation point after scouring, Δh2 is the distance between calculation point 2 and the previous calculation point after scouring, and Δh nsc is the distance between the calculation point nsc after scouring and the previous calculation point, nsc is the number of remaining calculation points; R'1 is an nsc×1 column vector, where the first element corresponds to the assumed effective gravity at the first calculation point after scouring, and the elements of the last nsc-1 items are all 0, γ' sc_1 It is the assumed effective weight at the first calculation point after scouring.

[0024] As a preferred technical solution of the present invention: in step S5, for the first calculation point, according to the calculation theory of scour unloading effect under homogeneous soil conditions, the calculated value of the mechanical parameters after scour at the first calculation point is obtained, wherein the calculated value of the effective weight of the first calculation point after scour is γ sc_1 , update the vertical stress expression of the calculation point 2 below:

[0025] σ 1sc_2 =(Δh1Δh2…Δh nsc )R'2

[0026] R'2=(γ sc_1 γ' sc_2 0…0) T

[0027] In the formula, σ 1sc_2 is the vertical stress at calculation point 2 after scouring; R'2 is a nsc×1 column vector, where the first two elements correspond to the calculated effective weight value γ at calculation point 1 after scouring sc_1 、Calculate the effective weight assumed value γ' at point 2 sc_2 , the elements of the last nsc-2 items are all 0;

[0028] Based on the vertical stress expression at calculation point 2 and the calculation theory of scour unloading effect under homogeneous soil conditions, the calculated values ​​of mechanical parameters after scour at calculation point 2 are obtained, including the calculated value of effective weight after scour γ sc_2 , update the vertical stress expression near the calculation point 3 below; and so on, obtain the calculated values ​​of the mechanical parameters after scouring at the final calculation point, including the calculated value of the effective weight γ at the final calculation point sc_nsc .

[0029] As a preferred technical solution of the present invention: in the step S6, the soil layers are re-divided according to the distribution information of the remaining calculation points after scouring, the total number of soil layers is nsc, the actual thickness of the soil layer is the calculation point spacing, and the mechanical parameters of the soil layer are the calculated values ​​of the mechanical parameters after scouring at the corresponding calculation points.

[0030] The calculated thickness of the first soil layer after scouring, ΔH1, is:

[0031] ΔH1=Δh1

[0032] In the formula, Δh1 is the actual thickness of the first soil layer after scouring;

[0033] According to the calculation theory of layered soil effect, the first soil layer after scouring is regarded as the same soil type as the adjacent soil layer below. The equivalent thickness of the first soil layer after scouring is solved by the equivalent method of the ultimate soil resistance integral of the soil layer. As shown below:

[0034]

[0035] In the formula, p ult_1 is the ultimate soil resistance of the first soil layer after scouring; p ult_2 is the ultimate soil resistance of the second soil layer after scouring;

[0036] Based on the equivalent thickness of the first soil layer after scouring Determine the adjacent soil layer below, that is, the calculated thickness of the second soil layer ΔH2 is:

[0037]

[0038] Where Δh2 is the actual thickness of the second soil layer;

[0039] According to the calculation theory of layered soil effect, the second soil layer is regarded as the same soil type as the adjacent soil layer below, and the equivalent thickness of the second soil layer is solved Update the calculated thickness of the adjacent soil layer below ΔH3; and so on, get the final equivalent thickness of the soil layer

[0040] In a second aspect, the present invention provides a device for calculating the scour effect of a layered soil mass of an offshore single pile foundation, comprising:

[0041] A construction module is used to construct a calculation model of an offshore wind turbine single pile foundation according to the size of the single pile foundation, soil layer information, and scouring depth, wherein a series of calculation points from the seabed mud surface to the pile end are established in the calculation model to determine the vertical stress distribution before and after scouring;

[0042] Analysis module: The analysis sequence is to first calculate the scour unloading effect for each calculation point along the depth direction through a cyclic iteration method, update the soil mechanical parameters at each point, and then redivide the soil layering, and then carry out the layered soil effect calculation to obtain the final equivalent thickness of the soil.

[0043] In a third aspect, the present invention provides a computer-readable storage medium, comprising a program, which, when executed on a computer, enables the computer to execute the method as claimed in any one of claims 1 to 7.

[0044] In a fourth aspect, the present invention provides an execution device, comprising a processor and a memory, wherein the processor is coupled to the memory;

[0045] The memory is used to store programs.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] In the method disclosed in this application, by establishing a series of calculation points from the seabed mud surface to the pile end depth of the single pile foundation, the vertical stress distribution state at each point before and after scouring is obtained, and then the scouring unloading effect calculation is carried out in a cyclic iteration along the depth direction, the soil mechanical parameters at each point are updated, and then the soil layering is re-divided, and then the layered soil effect calculation is carried out to obtain the final equivalent thickness of the soil. This method improves the application of the scouring effect calculation theory to complex layered soil conditions, realizes the joint analysis of the scouring unloading effect and layered soil effect calculation theory, and provides theoretical support and methodological basis for the subsequent work of the single pile foundation of offshore wind turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A flowchart of calculating the scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions provided by an exemplary embodiment is shown;

[0050] Figure 2A schematic diagram of a single pile foundation and soil layers provided by an exemplary embodiment is shown;

[0051] Figure 3 A schematic diagram of calculation point numbering and distribution provided by an exemplary embodiment is shown;

[0052] 4(a)-(b) show effective weight and OCR calculation result diagrams provided by an exemplary embodiment;

[0053] Figure 5 A schematic diagram of a soil layer thickness equivalent process provided by an exemplary embodiment is shown;

[0054] Figure 6 A block diagram of a calculation device for scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions provided by an exemplary embodiment is shown;

[0055] Figure 7 A block diagram of the execution device provided by an exemplary embodiment is shown. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0057] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices. The naming or numbering of steps in this application does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The process steps that have been named or numbered can change the execution order according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved. The division of units in this application is a logical division. There may be other division methods in actual application. For example, multiple units may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection between units may be electrical or other similar forms, which are not limited in this application. Moreover, the units or sub-units described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed in multiple circuit units, and some or all of the units may be selected according to actual needs to achieve the purpose of the present application.

[0058] Example 1

[0059] Please refer to Figure 1 , Figure 1 A flow chart of a method for calculating the scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions provided by an exemplary embodiment is shown.

[0060] The following is an example of a common calculation. The method includes the following steps:

[0061] S1. Determine the geometric dimensions of the offshore wind turbine single pile foundation and determine the soil layer thickness and mechanical parameters above the pile end of the single pile foundation, where the single pile foundation pile diameter D = 5m, and the pile length under the mud surface L = 15m;

[0062] In this embodiment, the soil stratification and mechanical parameters above the pile end are shown in Table 1. Figure 2 The location of the single pile foundation and the soil layer distribution are shown.

[0063] Table 1 Soil stratification and mechanical parameters above the pile tip

[0064]

[0065]

[0066] S2. Construct several calculation points along the depth direction from the mud surface before scouring to the pile end, and take Z int_1 =0.1m, that is, the first calculation point is 0.1m below the mud surface, and the final point is at the pile end Z int_150 = 15m, the distance between each point is 0.1m, and the total number of calculation points n = 150. The distribution of calculation points is as follows Figure 3 As shown;

[0067] The vertical stress σ at each calculation point is calculated according to the following formula: 1int , the vertical stress at each calculation point is obtained, as shown in Table 2;

[0068]

[0069] D i =(0 … 1 … 0) (2)

[0070] Table 2 Vertical stress at each calculation point before scour

[0071]

[0072]

[0073] S3. Determine the scouring depth S around the single pile foundation d , where the local scour depth S dl is 2m, and the global scour depth S dg is 1m, and the scour depth S is obtained d =2+1=3m;

[0074] Determine the number of remaining soil layers after scouring, the number of calculation points, and the spacing between each calculation point. Among them, the remaining soil layer after scouring is msc = 4-1 = 3, the remaining number of calculation points is nsc = 150-3 / 0.1 = 120, the first calculation point after scouring is located 0.1m below the mud surface, and the spacing between the remaining calculation points is 0.1m;

[0075] S4. Assume that the effective weight of the first calculation point after scouring is γ' sc_1 The effective weights of the remaining calculation points are assumed to be γ' sc_k ;

[0076] For the first calculation point after scouring, the vertical stress is calculated according to the following formula:

[0077] R'1=(γ' sc_1 0 … 0)T (3)

[0078]

[0079] S5. For the first calculation point after scouring, the soil layer is clay. According to the calculation theory of scouring unloading effect under the corresponding homogeneous soil condition, the effective weight γ of this point after scouring is calculated. sc_1 =9.8946kN / m 3 , OCR = 26.1476, undrained shear strength Cu sc_1 =15.6183kN, porosity esc = 1.2733;

[0080] According to the above calculation results, the vertical stress expression of the calculation point below this point is updated as follows:

[0081] R'2=(γ sc_1 γ' sc_2 0...0) T (5)

[0082]

[0083] Similarly, the mechanical parameters of the calculation points after scouring are summarized in Table 3; the distribution diagrams of the effective weight and OCR along the depth direction of the calculation points after scouring are shown in Figures 4(a) and (b).

[0084] Table 3 Mechanical parameters at the calculation point after scouring

[0085]

[0086]

[0087] S7. Divide the soil layers according to the distribution information of the remaining calculation points after scouring. There are nsc=120 soil layers in total. The thickness of each soil layer is determined to be 0.1m based on the calculation point spacing.

[0088] After the soil layers are redivided, for the first soil layer, its calculated thickness ΔH1 is calculated as follows:

[0089] ΔH1=Δh1=0.1m (7)

[0090] According to the calculation theory of layered soil effect, the first soil layer and the adjacent soil layer below are both clay, and the relevant parameters are shown in Table 2. The equivalent thickness of the first soil layer is calculated by the following formula:

[0091]

[0092] By analogy, the equivalent thickness of each layer of soil along the depth direction is obtained. The schematic diagram of the calculation process is shown in Figure 5The calculation results are summarized in Table 4, and the final equivalent thickness of the soil layer is obtained.

[0093] Table 4 Mechanical parameters at the calculation point after scouring

[0094]

[0095]

[0096] In summary, the present invention provides a method for calculating the scour effect of layered soil of an offshore single pile foundation, which can provide calculation convenience for professionals in related fields.

[0097] Example 2

[0098] Please refer to Figure 6 , which shows a block diagram of a device for calculating the scour effect of a layered soil body of a single pile foundation at sea provided by the present application. The device 200 includes:

[0099] The analysis module 201 is used to construct a calculation model of an offshore wind turbine single pile foundation according to the size of the single pile foundation, soil layer information, and scouring depth, wherein a series of calculation points from the seabed mud surface to the pile end are established in the corresponding calculation model to determine the vertical stress distribution before and after scouring;

[0100] Analysis module 202, the analysis sequence is to first calculate the scour unloading effect for each calculation point along the depth direction through a cyclic iteration method, update the soil mechanical parameters at each point, and then redivide the soil layer situation, and then carry out the layered soil effect calculation to obtain the final equivalent thickness of the soil.

[0101] Since the above methods have been discussed in detail, the specific implementation of the above modules will not be repeated here.

[0102] Example 3

[0103] Next, an execution device provided by an embodiment of the present application is introduced. Figure 6 , Figure 6 This is a schematic diagram of a structure of an execution device provided in an embodiment of the present application. The execution device 300 can be specifically manifested as an autonomous driving vehicle, a mobile phone, a tablet, a laptop computer, a desktop computer, a monitoring data processing device, etc., which is not limited here. Figure 1 The functions of the execution device in the corresponding embodiment. Specifically, the execution device 300 includes: a receiver 301, a transmitter 302, a processor 303 and a memory 304 (wherein the number of the processor 303 in the execution device 300 can be one or more, Figure 7In the example of FIG. 3 , the processor 303 may include an application processor 3031 and a communication processor 3032. In some embodiments of the present application, the receiver 301, the transmitter 302, the processor 303 and the memory 304 may be connected via a bus or other means.

[0104] The memory 304 may include a read-only memory and a random access memory, and provides instructions and data to the processor 303. A portion of the memory 304 may also include a non-volatile random access memory (NVRAM). The memory 304 stores processor and operation instructions, executable modules or data structures, or subsets thereof, or extended sets thereof, wherein the operation instructions may include various operation instructions for implementing various operations.

[0105] The processor 303 controls the operation of the execution device. In a specific application, the various components of the execution device are coupled together through a bus system, wherein the bus system includes not only a data bus but also a power bus, a control bus, and a status signal bus, etc. However, for the sake of clarity, various buses are referred to as bus systems in the figure.

[0106] The method disclosed in the above embodiment of the present application can be applied to the processor 303, or implemented by the processor 303. The processor 303 can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 303. The above processor 303 can be a general-purpose processor, a digital signal processor (digital signal processing, DSP), a microprocessor or a microcontroller, and can further include an application specific integrated circuit (application specific integrated circuit, ASIC), a field programmable gate array (field-programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The processor 303 can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to be executed, or the hardware and software modules in the decoding processor can be combined and executed. The software module may be located in a storage medium mature in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 304, and the processor 303 reads the information in the memory 304 and completes the steps of the above method in combination with its hardware.

[0107] The receiver 301 can be used to receive inputted digital or symbol information, and generate signal input related to the relevant settings and function control of the execution device. The transmitter 302 can be used to output the digital or symbol information through the first interface; the transmitter 302 can also be used to send instructions to the disk group through the first interface to modify the data in the disk group; the transmitter 302 can also include a display device such as a display screen.

[0108] In the embodiment of the present application, the processor 303 is used to execute Figure 1 The specific manner in which the application processor 3031 in the processor 303 performs the above steps is the same as that in the present application. Figure 1 The corresponding method embodiments are based on the same concept, and the technical effects they bring are the same as those in this application. Figure 1 The corresponding method embodiments are the same. For specific contents, please refer to the description in the method embodiments shown above in this application, which will not be repeated here.

[0109] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A method for calculating the scour effect of layered soil of an offshore single pile foundation, characterized in that: The following steps are involved: S1. Determine the geometric dimensions of the offshore wind turbine single pile foundation, the soil layer distribution information above the pile end and the mechanical parameters; S2, construct several calculation points along the depth direction from the mud surface before scouring to the pile end and calculate the initial vertical stress at each calculation point; S3. Determine the scouring depth around the single pile foundation, the number of remaining soil layers after scouring, the number of calculation points and the distance between each calculation point; S4, assuming the effective weight of each calculation point after scouring, and determining the vertical stress expression of the first calculation point after scouring based on the assumed effective weight of the calculation point after scouring; S5. According to the calculation theory of scour unloading effect under homogeneous soil conditions, solve the mechanical parameters of the soil at the first calculation point after scour and update the vertical stress expression of the adjacent calculation point below, and so on, until the mechanical parameters of the final calculation point after scour are updated; S6. Re-divide the soil layering according to the distribution information of the remaining calculation points after scouring; Determine the calculated thickness of the first soil layer after scouring; based on the layered soil effect calculation theory and the updated mechanical parameters, solve the equivalent thickness of the first soil layer after scouring and determine the calculated thickness of the adjacent soil layer below, and so on, until the equivalent thickness of the last soil layer is calculated.

2. The method for calculating the scour effect of layered soil of a single pile foundation at sea according to claim 1 is characterized in that: The geometric dimensions of the offshore wind turbine monopile foundation in step S1 include: the monopile foundation diameter D, the pile length L below the mud surface; The soil layer distribution information and mechanical parameters above the pile end of the single pile foundation include: the total number of soil layers above the pile end m, the thickness of each soil layer H, the effective weight of each soil layer γ int ; Among them, the mechanical parameters of clay soil layer also include: soil moisture content ω int , initial undrained shear strength Cu int , compression index C c_int , expansion index C s_int 、Effective friction angle of drainage condition φ cu_int ; The mechanical parameters of sandy soil layers also include: critical internal friction angle φ s_int , relative density Dr int , maximum porosity emax, minimum porosity emin, soil particle density Gs, uniaxial unloading coefficient C ur .

3. The method for calculating the scour effect of layered soil of a single pile foundation at sea according to claim 1 is characterized in that: In step S2, the first calculation point along the depth direction from the mud surface before scouring to the pile end is selected at a non-mud surface position below the seabed mud surface and close to the mud surface. The depth of the final calculation point should be consistent with the depth of the pile end of the single pile foundation; the calculation points can be evenly distributed with equal intervals or unequal intervals.

4. The method for calculating the scour effect of layered soil of a single pile foundation at sea according to claim 3 is characterized in that: The initial vertical stress at each calculation point is: D i ＝(0…1…0) In the formula, σ 1int_i is the initial vertical stress at calculation point i before scouring, D i is a 1×m row vector, where the kth column element is 1, and the remaining position elements are all 0, k is the soil layer number where the calculation point i is located, k∈[1,m]; γ int_1 is the effective weight of soil layer 1 before scouring, γ int_2 is the effective weight of soil layer 2 before scouring, γ int_m is the effective weight of soil layer m before scouring; H1 is the thickness of soil layer 1 before scouring, H2 is the thickness of soil layer 2 before scouring, H m-1 is the thickness of the soil layer m-1 before scouring; Z int_i is the depth of calculation point i before scouring, and m is the number of soil layers.

5. The method for calculating the scour effect of layered soil of an offshore single pile foundation according to claim 1 is characterized by: In step S4, the vertical stress at the first calculation point is determined based on the assumed effective weight after scouring as: s 1sc_1 =(Δh1Δh2…Δh nsc )R'1 R'1=(γ' sc_1 0…0) T In the formula, σ 1sc_1 is the vertical stress at calculation point 1 after scouring, Δh1 is the distance below the mud surface of the first calculation point after scouring, Δh2 is the distance between calculation point 2 and the previous calculation point after scouring, and Δh nsc is the distance between the calculation point nsc after scouring and the previous calculation point, nsc is the number of remaining calculation points; R'1 is an nsc×1 column vector, where the first element corresponds to the assumed effective gravity at the first calculation point after scouring, and the elements of the last nsc-1 items are all 0, γ' sc_1 It is the assumed effective weight at the first calculation point after scouring.

6. The method for calculating the scour effect of layered soil of a single pile foundation at sea according to claim 5, characterized in that: In step S5, for the first calculation point, according to the calculation theory of scour unloading effect under homogeneous soil conditions, the calculated value of the mechanical parameters after scour at the first calculation point is obtained, where the calculated value of the effective weight of the first calculation point after scour is γ sc_1 , update the vertical stress expression of the calculation point 2 below: s 1sc_2 =(Δh1Δh2…Δh nsc )R'2 R'2=(γ sc_1 c' sc_2 0…0) T In the formula, σ 1sc_2 is the vertical stress at calculation point 2 after scouring; R'2 is a nsc×1 column vector, where the first two elements correspond to the calculated effective weight value γ at calculation point 1 after scouring sc_1 、Calculate the effective weight assumed value γ' at point 2 sc_2 , the elements of the last nsc-2 items are all 0; Based on the vertical stress expression at calculation point 2 and the calculation theory of scour unloading effect under homogeneous soil conditions, the calculated values ​​of mechanical parameters after scour at calculation point 2 are obtained, including the calculated value of effective weight after scour γ sc_2 , update the vertical stress expression near the calculation point 3 below; and so on, obtain the calculated values ​​of the mechanical parameters after scouring at the final calculation point, including the calculated value of the effective weight γ at the final calculation point sc_nsc .

7. The method for calculating the scour effect of layered soil of a single offshore pile foundation according to claim 1 is characterized by: In the step S6, the soil layers are re-divided according to the distribution information of the remaining calculation points after scouring, the total number of soil layers is nsc, the actual thickness of the soil layer is the calculation point spacing, and the mechanical parameters of the soil layer are the calculated values ​​of the mechanical parameters after scouring at the corresponding calculation points; The calculated thickness of the first soil layer after scouring, ΔH1, is: ΔH1=Δh1 In the formula, Δh1 is the actual thickness of the first soil layer after scouring; According to the calculation theory of layered soil effect, the first soil layer after scouring is regarded as the same soil type as the adjacent soil layer below. The equivalent thickness of the first soil layer after scouring is solved by the equivalent method of the ultimate soil resistance integral of the soil layer. As shown below: In the formula, p ult_1 is the ultimate soil resistance of the first soil layer after scouring; p ult_2 is the ultimate soil resistance of the second soil layer after scouring; Based on the equivalent thickness of the first soil layer after scouring Determine the adjacent soil layer below, that is, the calculated thickness of the second soil layer ΔH2 is: Where Δh2 is the actual thickness of the second soil layer; According to the calculation theory of layered soil effect, the second soil layer is regarded as the same soil type as the adjacent soil layer below, and the equivalent thickness of the second soil layer is solved Update the calculated thickness of the adjacent soil layer below ΔH3; and so on, get the final equivalent thickness of the soil layer 8. A device for calculating the scour effect of layered soil of a single offshore pile foundation, characterized in that: include: A construction module is used to construct a calculation model of an offshore wind turbine single pile foundation according to the size of the single pile foundation, soil layer information, and scouring depth, wherein a series of calculation points from the seabed mud surface to the pile end are established in the calculation model to determine the vertical stress distribution before and after scouring; Analysis module: the analysis sequence is to first calculate the scour unloading effect for each calculation point along the depth direction through a cyclic iteration method, update the soil mechanical parameters at each point, and then re-divide the soil layer situation, and then carry out the layered soil effect calculation to obtain the final equivalent thickness of the soil; The device for calculating the scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions is used to execute the steps in the method for calculating the scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that: The invention comprises a program, which, when being executed on a computer, causes the computer to execute the method according to any one of claims 1 to 7.

10. An execution device, characterized in that: comprising a processor and a memory, wherein the processor is coupled to the memory; The memory is used to store programs; The processor is configured to execute the program in the memory so that the execution device executes the method according to any one of claims 1 to 7.

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