A method, device, storage medium and equipment for calculating the scour effect of layered soil of an offshore single pile foundation

Abstract

The present application discloses a method, device, storage medium and equipment for calculating the scour effect of layered soil of an offshore single pile foundation, including: S1, determining the size, soil layer distribution and mechanical parameters of the single pile foundation; S2, constructing several calculation points in the depth direction and determining the vertical stress; S3, determining the scour depth, soil layer after scouring and calculation point information; S4, assuming the effective weight of the calculation point after scouring and determining the vertical stress expression; S5, solving the mechanical parameters at the first calculation point after scouring and updating the vertical stress expression of the adjacent point below, and so on, until the mechanical parameters of the final point after scouring are determined; S6, re-dividing the soil layer situation; determining the calculated thickness of the first soil layer after scouring, solving its equivalent thickness to determine the calculated thickness of the adjacent soil layer below, and so on, until the equivalent thickness of the last soil layer is determined. The present invention can accurately calculate the impact of the scour effect of an offshore single pile foundation under layered soil conditions, and provide key analysis means 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 monopile foundations, with their low cost, simple construction, and reliable structure, have become a crucial component of my country's offshore wind power development. During the service life of a wind turbine, wave and current action will cause erosion and stripping of the soil surrounding the pile. Simultaneously, the remaining soil beneath, affected by unloading, shifts from a normally consolidated state to an overconsolidated state, altering some mechanical parameters and the original soil stratification. This scour and unloading effect has a significant impact on the accurate analysis of pile-soil interactions.

[0003] Theoretical methods used in related technologies are only applicable to homogeneous clay or sand foundations. In practice, offshore geology often presents complex, layered soils, making these theoretical methods ineffective. Furthermore, layered soil conditions also impact the accurate calculation of pile-soil interaction, requiring consideration during the construction of analytical models. Therefore, a method for calculating the scour unloading effect of single-pile foundations for offshore wind turbines that considers layered soil conditions is urgently needed. 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 impact 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 amount of remaining soil layer after scouring, the number of calculation points, and the spacing between the calculation points;

[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. Based on the calculation theory of scour unloading effect under homogeneous soil conditions, solve the post-scour mechanical parameters of the soil at the first calculation point after scour and update the vertical stress expression of the adjacent calculation point below. Repeat this process until the post-scour mechanical parameters of the final calculation point 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; based on the calculation theory of layered soil effects 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.

[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: the single pile foundation diameter D, the pile length L below 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 under drainage conditions 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 in 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.

[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] Where, 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 rest of the position elements are 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 before scouring m-1; 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 gravity after scouring as:

[0021] σ 1sc_1 =(Δh1Δh2…Δh nsc )R'1

[0022] R'1=(γ' sc_1 0…0) T

[0023] Where, σ 1sc_1 is the vertical stress at calculation point 1 after scouring, Δh1 is the distance below the mud surface from 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, and 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, and 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] Where, 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 weighted 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 spacing between the calculation points, 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 is ΔH1:

[0031] ΔH1=Δh1

[0032] Where 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 in the following formula:

[0034]

[0035] Where 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, to obtain 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 layered soil of an offshore single pile foundation, comprising:

[0041] A construction module is used to construct a calculation model for an offshore wind turbine single pile foundation based on the single pile foundation dimensions, soil layer information, and scour depth. In this calculation model, a series of calculation points from the seabed mud surface to the pile end are established to determine the vertical stress distribution before and after scour;

[0042] In the analysis module, the analysis sequence is to first calculate the scour unloading effect for each calculation point along the depth direction through a cyclic iterative 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.

[0043] In a third aspect, the present invention provides a computer-readable storage medium comprising a program, which, when executed on a computer, causes the computer to execute the method according to 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] The method disclosed in this application establishes a series of calculation points at the depth from the seabed mud surface to the pile end of a single pile foundation to obtain the vertical stress distribution state at each point before and after scouring. The scouring unloading effect calculation is then performed in a cyclic iterative manner along the depth direction, the soil mechanical parameters at each point are updated, and the soil stratification is then re-divided. The layered soil effect calculation is then performed to obtain the final equivalent thickness of the soil. This method improves the application of scouring effect calculation theory to complex layered soil conditions, realizes the combined analysis of scouring unloading effect and layered soil effect calculation theory, and provides theoretical support and methodological basis for the subsequent development of single pile foundations for 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, a brief introduction is given below to 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 any creative work.

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

[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] FIG4(a)-(b) shows 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 device for calculating the scour unloading effect of a single pile foundation of an offshore wind turbine considering layered soil conditions is shown, provided by an exemplary embodiment;

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

[0056] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to 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 herein can be implemented in a sequence other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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 that are 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 be changed in 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 described in this application is a logical division. In actual implementation, other divisions may be used. For example, multiple units may be combined or integrated into another system, or some features may be ignored or not implemented. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through interfaces, and the indirect coupling or communication connection between units may be electrical or other similar forms, all of which are not limited in this application. Furthermore, the units or subunits described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed across multiple circuit units. Some or all of these units may be selected based on actual needs to achieve the objectives of this application.

[0058] Example 1

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

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

[0061] S1. Determine the geometric dimensions of the offshore wind turbine single pile foundation and the soil thickness and mechanical parameters above the pile end. The pile diameter D is 5m, and the pile length below the mud surface L is 15m.

[0062] In this embodiment, the soil stratification and mechanical parameters above the pile tip are shown in Table 1. Figure 2 The location of the single pile foundation and the distribution of soil layers 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, 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] Calculate the vertical stress σ at each calculation point 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 calculation points. The remaining soil layers after scouring are msc = 4-1 = 3, and the number of remaining calculation points is nsc = 150-3 / 0.1 = 120. The first calculation point after scouring is 0.1 m below the mud surface, and the spacing between the remaining calculation points is 0.1 m.

[0075] S4. Assume that the effective weight of the first calculation point after scouring is γ' sc_1 The effective weighted assumed values ​​of the remaining calculation points are expressed as 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 of the point after scouring γ is calculated. sc_1 =9.8946kN / m 3 , OCR=26.1476, undrained shear strength Cu sc_1 =15.6183kN, porosity esc=1.2733;

[0080] Based on the above calculation results, the vertical stress expression of the adjacent 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 of 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 a total of nsc=120 soil layers. The thickness of each soil layer is determined to be 0.1m based on the calculation point spacing.

[0088] After redividing the soil layers, 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. 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 as follows: 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 in a single offshore 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 layered soil on a single offshore pile foundation provided by the present application. The device 200 includes:

[0099] Analysis module 201 is used to construct a calculation model for an offshore wind turbine single pile foundation based on the single pile foundation dimensions, soil layer information, and scour depth. 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 scour;

[0100] Analysis module 202, the analysis sequence is to first perform scour unloading effect calculation 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 perform 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, we will introduce an execution device provided by the embodiment of the present application. Figure 6 , Figure 6 This is a schematic diagram of the structure of the execution device provided in the 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 execution device 300 includes a receiver 301, a transmitter 302, a processor 303, and a memory 304 (the number of the processor 303 in the execution device 300 can be one or more, Figure 7(taking one processor as an example), 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] Memory 304 may include read-only memory and random access memory, and provides instructions and data to processor 303. A portion of memory 304 may also include non-volatile random access memory (NVRAM). Memory 304 stores processor and operation instructions, executable modules, or data structures, or subsets or extended sets thereof. Operation instructions may include various operation instructions for implementing various operations.

[0105] Processor 303 controls the operation of the execution device. In specific applications, the various components of the execution device are coupled together via a bus system. In addition to a data bus, the bus system may also include a power bus, a control bus, and a status signal bus. However, for clarity, all bus systems are referred to as a bus system in the figure.

[0106] The methods disclosed in the above embodiments 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. During implementation, each step of the above method can be completed by hardware integrated logic circuits in the processor 303 or software instructions. The above processor 303 can be a general-purpose processor, a digital signal processing (DSP), a microprocessor or a microcontroller, and can further include an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and 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-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of the present application can be directly implemented as being executed by a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium well-known in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in memory 304, and processor 303 reads the information in memory 304 and performs the steps of the above method in conjunction with its hardware.

[0107] Receiver 301 can be used to receive input data or rare character information and generate signal input related to executing device-related settings and function control. Transmitter 302 can be used to output data or rare character information via a first interface. Transmitter 302 can also be used to send instructions to the disk pack via the first interface to modify data in the disk pack. 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 method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection 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; the initial vertical stress at each calculation point is: Where, Calculation point before flushing i The initial vertical stress at for Row vector, where k The column element is 1, and the other position elements are 0. k Calculation point i Soil layer number, ; is the effective weight of soil layer 1 before scouring, is the effective weight of soil layer 2 before scouring, is the effective density of soil layer m before scouring; is the thickness of soil layer 1 before scouring, is the thickness of soil layer 2 before scouring, is the thickness of the soil layer before scouring in m-1; Calculation point before flushing i The depth, m is the number of soil layers; S3. Determine the scouring depth around the single pile foundation, the amount of remaining soil layer after scouring, the number of calculation points, and the spacing between the calculation points; 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. Based on the calculation theory of scour unloading effect under homogeneous soil conditions, solve the post-scour mechanical parameters of the soil at the first calculation point after scour and update the vertical stress expression of the adjacent calculation point below. Repeat this process until the post-scour mechanical parameters of the final calculation point are updated. S6. Re-divide the soil layers 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; re-divide the soil layers according to the distribution information of the remaining calculation points after scouring, and the total number of soil layers is nsc The actual thickness of the soil layer is the distance between the calculation points, and the mechanical parameters of the soil layer are the calculated values ​​of the mechanical parameters after scouring at the corresponding calculation points. Calculated thickness of the first soil layer after scouring for: Where, 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: Where, is the ultimate soil resistance of the first soil layer after scouring; 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, calculate the thickness of the second soil layer for: Where, 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 ; By analogy, the final equivalent thickness of the soil layer is obtained .

2. The method for calculating the scour effect of layered soil of a single offshore pile foundation according to claim 1 is characterized in that: The geometric dimensions of the offshore wind turbine monopile foundation in step S1 include: the diameter of the monopile foundation D , Pile length below mud surface L ; 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 , thickness of each soil layer , effective density of each soil layer ; Among them, the mechanical parameters of clay soil layer also include: soil moisture content , initial undrained shear strength , compression index , expansion index , effective friction angle under drainage conditions ; The mechanical parameters of sandy soil layers also include: critical internal friction angle , relative density , maximum porosity ratio , minimum porosity ratio , soil particle density , Single-axis unloading coefficient .

3. The method for calculating the scour effect of layered soil of an offshore single pile foundation according to claim 1 is characterized in that: In step S2, the first calculation point in 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 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 gravity after scouring: Where, is the vertical stress at calculation point 1 after scouring, The distance below the mud surface where the first calculation point is located after scouring. is the distance between calculation point 2 and the previous calculation point after scouring, Calculation point after flushing The distance from the last calculated point, Calculate points for the remainder; for Column vector, where the first element corresponds to the assumed effective weight at the first calculation point after flushing, and the latter The elements of each item are all 0, It is the assumed effective weight at the first calculation point after scouring.

5. The method for calculating the scour effect of layered soil of an offshore single pile foundation according to claim 4 is 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, wherein the calculated value of the effective weight of the first calculation point after scour is , update the vertical stress expression of the calculation point 2 below: Where, is the vertical stress at calculation point 2 after scouring; for Column vector, where the first two elements correspond to the effective weight calculation value at calculation point 1 after scouring , effective weighted assumed value at calculation point 2 ,back All elements of the item are 0; Based on the vertical stress expression at calculation point 2 above, and according to 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. , update the vertical stress expression near the calculation point 3 below; and so on, get the calculated value of the mechanical parameters after scouring at the final calculation point, including the calculated value of the effective weight at the final calculation point .

6. 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 for an offshore wind turbine single pile foundation based on the single pile foundation dimensions, soil layer information, and scour depth. In this calculation model, a series of calculation points from the seabed mud surface to the pile end are established to determine the vertical stress distribution before and after scour; 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 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 of 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 to 5.

7. A computer-readable storage medium, characterized in that The invention comprises a program, which, when being run on a computer, causes the computer to execute the method according to any one of claims 1 to 5.

8. 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 5.

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