Device and method for predicting scouring depth and scouring range of five-connected-cylinder jacket foundation

Abstract

The invention discloses a device and method for predicting the scouring depth and scouring range of a five-connected-cylinder jacket foundation, and relates to the technical field of offshore wind power engineering.The device comprises a simulation end and a control end, and the simulation end comprises a water tank, a five-connected-cylinder jacket foundation model and collection equipment; the control end is used for simulating the scouring process of the five-connected-cylinder jacket foundation model according to the determined test scheme to obtain corresponding original scouring data, and the control end is used for deducing a model prediction formula according to the original scouring data and working condition parameters in the test scheme, converting the model prediction formula into a prototype prediction formula through scale conversion, and outputting the prototype prediction formula to the foundation model. The scouring depth and the scouring range of the five-connected-cylinder jacket foundation entity are calculated according to the prototype prediction formula, calculation and verification are conducted on the five-connected-cylinder scouring depth prediction and range formula through a large amount of test data, and the method can be used for rapid prediction of the scouring depth and range of the follow-up similar foundation type.

Description

Technical Field

[0001] The present application relates to the technical field of offshore wind power engineering, and particularly relates to a device and method for predicting the scour depth and scour range of a five-barrel jacket foundation. Background Art

[0002] With the gradual advancement of offshore wind power towards the deep and far sea, more and more fixed foundation types suitable for the deep and far sea area have emerged in an endless stream, especially the five-barrel jacket foundation (MBJF). Different from single-pile foundations, the lower cylinders of the five-barrel jacket foundation have a large diameter and a shallow burial depth. Under the action of waves and currents, the soil particles around the foundation are easily entrained and lost, which in turn affects the in-situ ultimate bearing capacity and dynamic response characteristics of the foundation. The flow conditions around different foundation structural forms are quite different, especially for the five-barrel jacket foundation. Therefore, the scour depth prediction methods summarized by predecessors for single-pile / single-cylinder foundations are difficult to predict the five-barrel jacket foundation. In addition, there are few reports on the prediction of the scour range. Therefore, it is urgent to conduct research on the prediction of the scour depth and scour range of this emerging foundation type. Summary of the Invention

[0003] The purpose of the present application is to provide a device and method for predicting the scour depth and scour range of a five-barrel jacket foundation, which can predict the scour depth and scour range of the five-barrel jacket foundation of offshore wind power.

[0004] To achieve the above purpose, the present application provides the following solutions:

[0005] In a first aspect, the present application provides a device for predicting the scour depth and scour range of a five-barrel jacket foundation, including:

[0006] A simulation end, configured to simulate the scour process of the five-barrel jacket foundation model according to the determined test plan, and obtain corresponding original scour data, where the original scour data includes original scour depth data and original scour range data;

[0007] A control end, connected to the simulation end, configured to derive a model prediction formula based on the original scour data and the working condition parameters in the test plan, convert the model prediction formula into a prototype prediction formula through scale conversion, and calculate the scour depth and scour range of the five-barrel jacket foundation in-kind according to the prototype prediction formula;

[0008] The simulation end specifically includes:

[0009] A water tank, configured to simulate the water flow conditions of the real marine environment;

[0010] A five-barrel jacket foundation model, arranged in the water tank;

[0011] A data acquisition device for acquiring flow velocity data and the original scour data around the five - cylinder jacket foundation model.

[0012] In a second aspect, the present application provides a method for predicting the scour depth and scour range of a five - cylinder jacket foundation. The method for predicting the scour depth and scour range of the five - cylinder jacket foundation is executed by using the device for predicting the scour depth and scour range of the five - cylinder jacket foundation described in the first aspect. The method for predicting the scour depth and scour range of the five - cylinder jacket foundation includes:

[0013] According to the determined test scheme, use the simulation end to simulate the scour process of the five - cylinder jacket foundation model to obtain the corresponding original scour data;

[0014] Derive a model prediction formula based on the original scour data and the working condition parameters in the test scheme, convert the model prediction formula into a prototype prediction formula through scale conversion, and calculate the scour depth and scour range of the five - cylinder jacket foundation in kind according to the prototype prediction formula.

[0015] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0016] The present application provides a device and method for predicting the scour depth and scour range of a five - cylinder jacket foundation. The device includes a simulation end and a control end. The simulation end includes a water tank, a five - cylinder jacket foundation model, and a data acquisition device, and is used to simulate the scour process of the five - cylinder jacket foundation model according to the determined test scheme to obtain the corresponding original scour data. The control end is used to derive a model prediction formula based on the original scour data and the working condition parameters in the test scheme, convert the model prediction formula into a prototype prediction formula through scale conversion, and calculate the scour depth and scour range of the five - cylinder jacket foundation in kind according to the prototype prediction formula. By deriving and verifying the five - cylinder scour depth prediction and range formula through a large amount of test data, it can be used for the rapid prediction of the scour depth and range of subsequent similar foundation types, avoiding complicated test design and numerical simulation calculation work, and providing a theoretical basis and scientific support for the prediction of the scour depth and range of similar foundation types in offshore wind power. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of the simulation end in Embodiment 1 of the present application;

[0019] Figure 2 It is a schematic flow chart of a method for predicting the scour depth and scope of a five - barrel jacket foundation in Embodiment 2 of this application;

[0020] Figure 3 It is a schematic diagram of a device for predicting the scour depth and scope of a five - barrel jacket foundation in Embodiment 2 of this application;

[0021] Figure 4 It is a schematic diagram of a three - dimensional point cloud of topographic survey in Embodiment 2 of this application;

[0022] Figure 5 It is a schematic diagram of a five - barrel jacket foundation model in Embodiment 2 of this application;

[0023] Figure 6 It is a schematic diagram of flow velocity calibration in Embodiment 2 of this application;

[0024] Figure 7 It is a schematic diagram of time - history monitoring of the scour depth of a five - barrel foundation in Embodiment 2 of this application;

[0025] Figure 8 It is a schematic diagram of monitoring the scour scope of a five - barrel foundation in Embodiment 2 of this application;

[0026] Figure 9 It is a schematic diagram for comparing and verifying the scour depth prediction formula and the measured value of a five - barrel foundation in Embodiment 2 of this application;

[0027] Figure 10 It is a schematic diagram for comparing and verifying the scour scope prediction formula and the measured value;

[0028] Figure 11 It is a schematic diagram of the relationship between the scour depth and the scour scope change of a five - barrel foundation in Embodiment 2 of this application. Detailed implementation mode

[0029] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0030] To make the above - mentioned objects, features, and advantages of this application more obvious and understandable, the following further detailed description of this application is provided in conjunction with the accompanying drawings and specific implementation modes.

[0031] Embodiment 1

[0032] This embodiment provides a device for predicting the scour depth and scope of a five - barrel jacket foundation, including:

[0033] The simulation end is used to simulate the scouring process of the five-barrel jacket foundation model according to the determined test plan, and obtain corresponding original scouring data, where the original scouring data includes original scouring depth data and original scouring range data.

[0034] The control end is connected to the simulation end, and is used to derive a model prediction formula based on the original scouring data and the working condition parameters in the test plan, convert the model prediction formula into a prototype prediction formula through scale conversion, and calculate the scouring depth and scouring range of the five-barrel jacket foundation in-kind according to the prototype prediction formula. The working condition parameters include the foundation geometric dimension parameters, water flow parameters and model sand parameters of the five-barrel jacket foundation model. The foundation geometric dimension parameters include the side barrel diameter, barrel top height and barrel height. The water flow parameters include the average flow velocity, water depth and incoming flow angle. The model sand parameters include the critical starting flow velocity of the model sand, the internal friction angle of the model sand and the median grain size of the model sand. The model prediction formula includes a scouring depth prediction formula and a scouring range prediction formula.

[0035] The control end in this embodiment is specifically a computer.

[0036] As Figure 1 shown, the simulation end specifically includes:

[0037] A water tank for simulating the water flow conditions of the real marine environment.

[0038] The water tank is divided into: a steady water section, a first slope, a sand pool (test section), a second slope, and a water discharge section. The water tank is in the shape of a cuboid. During the construction process, ensure that the length, width and height dimensions of the water tank are sufficient to realize the simulation of reasonable water depth conditions. A movable guide rail frame is arranged above the test section for monitoring the flow velocity change and terrain survey work in the test section. The water tank is arranged in sequence from one end to the other end as a steady water section, a first slope, a sand pool (test section), a second slope, and a water discharge section. The steady water section includes a steady flow grid and a slope section for stabilizing the water flow and ensuring that the water flow enters the sand pool (test section) evenly and smoothly; the slope is used for the smooth transition of the incoming flow to the sand pool (test section) to ensure that the water flow does not cause significant disturbance when entering the sand pool (test section); the sand pool contains model sand and a five-barrel jacket foundation model for simulating the scouring morphology and its evolution around the five-barrel jacket foundation; the second slope is used for the smooth transition of the outflow to the water discharge section to avoid disturbing the sand pool (test section); the water discharge section is used to discharge all the incoming flow into the circulating water pool to supplement the recycled test water.

[0039] Instrumentation equipment (i.e., acquisition equipment), the instrumentation equipment includes a Vectrino Acoustic Doppler Velocimeter (ADV) from Nortek AS, Norway, with a sampling frequency of 200 Hz and a flow velocity measurement accuracy of ±0.5% of the measured value. It is set on the guide rail frame installed on the upper part of the above-mentioned flume test section, and is used to monitor the flow velocity around the five-barrel jacket foundation in real time in the test section, providing data for subsequent flow velocity calibration steps. The instrumentation equipment also includes a structured light 3D camera, specifically an ORBBEC Astra 2 series 3D sensing camera, which uses monocular structured light technology, has the advantages of high precision, low power consumption, rapid response, stability and reliability. The resolution of the captured image format is 1600 mm × 1200 mm, and the depth image data is generated by structured light bathymetry technology. It can collect and output the depth data of an object within the range of 0.6 m to 8 m. This photogrammetry technology can provide stable depth measurement performance with RMSE < 1.5 mm at 1 m under various ambient temperatures. It is set on the guide rail frame installed on the upper part of the above-mentioned flume test section, directly above the five-barrel jacket foundation, and is used to monitor the scour depth and scour range around the five-barrel jacket foundation in real time, providing data for subsequent model prediction and training of the scour depth and scour range.

[0040] Five-barrel jacket foundation model, set in the center of the test section, used to carry out the scour model test of the five-barrel jacket foundation.

[0041] Water supply device, used to supply water to the flume.

[0042] The water supply device adopted in this embodiment specifically includes:

[0043] Water tank, the water tank is set outside or underground the test flume, used to provide recycled water for the flume and receive the water from the drainage section.

[0044] Water pump, the water pump is set between the water tank and the pipeline leading to the flume, used to pump the test water in the water tank and transport it to the flume.

[0045] Based on the five-barrel jacket foundation scour depth and scour range prediction device in this embodiment, the scour depth prediction and range formula of the five-barrel can be derived and verified, which can be used for the rapid prediction of the scour depth and range of subsequent similar foundation types. The specific prediction process of the scour depth and scour range of the offshore wind power five-barrel jacket foundation using this device is shown in detail in Embodiment 2.

[0046] Embodiment 2

[0047] As Figure 2As shown in the figure, this embodiment provides a method for predicting the scour depth and scour range of a five - barrel jacket foundation. The method for predicting the scour depth and scour range of the five - barrel jacket foundation is executed by using the device for predicting the scour depth and scour range of the five - barrel jacket foundation described in Embodiment 1. The method for predicting the scour depth and scour range of the five - barrel jacket foundation includes:

[0048] S1: According to the determined test scheme, use the simulation end to simulate the scour process of the five - barrel jacket foundation model, and obtain the corresponding original scour data. Among them, the original scour data includes original scour depth data and original scour range data.

[0049] The process of determining the test scheme specifically includes:

[0050] 1) According to the physical parameters of the five - barrel jacket foundation, determine the scale ratios based on geometric similarity, gravity similarity, and kinematic similarity. Among them, the scale ratios include geometric scale ratio, flow velocity scale ratio, flow rate scale ratio, and time scale ratio;

[0051] 2) Determine the type of model sand according to the incipient flow velocity of the physical parameters of the five - barrel jacket foundation;

[0052] 3) Adjust the inflow rate of the simulation end, and use the acquisition device to collect the flow velocity data under different scour types. Among them, the scour types include movable - bed scour and clear - water scour. The scour types are determined based on the flow intensity, and the flow intensity is a variable determined according to the inflow rate of the simulation end and the critical incipient velocity of the model sand. The critical incipient velocity of the model sand is a variable calculated according to the parameters of the model sand;

[0053] 4) Calculate the scour time when reaching static equilibrium according to the flow velocity data;

[0054] 5) Determine the test scheme according to the scale ratios, the type of model sand, and the scour time.

[0055] S2: Derive the model prediction formula according to the original scour data and the working condition parameters in the test scheme, convert the model prediction formula into a prototype prediction formula through scale ratio conversion, and calculate the scour depth and scour range of the physical five - barrel jacket foundation according to the prototype prediction formula.

[0056] To make those skilled in the art more clear about the above process of this embodiment, the following is a specific explanation.

[0057] Step 1: Determine the scale ratios based on geometric similarity, gravity similarity, and kinematic similarity. The scale ratios include geometric scale ratio, flow velocity scale ratio, flow rate scale ratio, and time scale ratio.

[0058] Geometric similarity means that each geometric quantity at corresponding points in the two flow fields of the prototype and the model (simulation end) has a certain ratio, and this ratio relationship is the geometric scale. The scale of the flow field is equal to the scale of the model, that is, the horizontal scale λ l and the vertical scale λ h are both equal to the model scale selected for the test. The selection of the scale should be determined by avoiding the interference of the flume boundary. Specifically, it should be ensured that the maximum lateral dimension of the five-leg jacket foundation model is not greater than one-fifth of the flume width. Furthermore, the geometric scale during the test is obtained by taking the ratio of the maximum lateral dimension of the prototype of the five-leg jacket foundation to the maximum lateral dimension of the five-leg jacket foundation model.

[0059] Gravity similarity means that the ratio of inertial force to gravity in the two flow fields of the prototype and the model is equal, that is, the Froude numbers are equal. The velocity scale can be determined by the following formula.

[0060]

[0061]

[0062]

[0063] λ u =λ l 1 / 2 (4)

[0064] In the formula: Fr p is the flow Froude number of the prototype; Fr m is the flow Froude number of the model; u p is the flow velocity of the prototype; u m is the flow velocity of the model; g p is the flow gravity acceleration of the prototype; g m is the flow gravity acceleration of the model; L p is the flow characteristic length of the prototype; L m is the flow characteristic length of the model; λ L is the characteristic length scale; λ u is the velocity scale; λ l is the horizontal scale.

[0065] Kinematic similarity means that the directions of the corresponding velocities and accelerations at all corresponding points in the two flow fields of the prototype and the model are the same, and the ratios are equal, that is, their streamlines are geometrically similar. The calculation of the discharge scale can be obtained from formula (5) and formula (6) to get formula (7). The calculation of the time scale can be obtained from formula (8) to get formula (9).

[0066] λ Q =λ u ×λ A (5)

[0067] λ A = λ l 2 (6)

[0068] λ Q = λ l 5 / 2 (7)

[0069] λ t = λ L / λ u (8)

[0070] λ t = λ l 1 / 2 (9)

[0071] In the formula: λ Q is the flow scale ratio, λ A is the area scale ratio, λ t is the time scale ratio.

[0072] After determining the scale ratio, first, it can avoid the adverse effects of boundary effects caused by the site space during the test on the test results; second, based on the calculated model scale ratio, perform scale conversions of various physical quantities (horizontal scale ratio, vertical scale ratio, rate of change, flow velocity scale ratio, flow scale ratio, time scale ratio), and accurately predict the actual prototype results in combination with the model test results; third, based on the calculated model scale ratio, it is used to fabricate the five-barrel foundation model subsequently, and monitoring points are evenly arranged at the characteristic positions around the foundation to monitor the scour depth in real time.

[0073] Step 2: Select model sand and determine the scour type.

[0074] Purchase and lay model sands of various types and median particle sizes in the test flume, and carry out the calculation of the critical incipient velocity of the model sand. The calculation of the incipient velocity of the model sand can be carried out based on formula (10).

[0075]

[0076] In the formula, V cr is the critical incipient velocity of the model sand, h is the water depth, d is the median particle size of the model sand, γ s is the specific gravity of the model sand, and γ is the specific gravity of water. By calculation, select the incipient velocity close to the prototype, determine the median particle size of the model sand, bituminous coal fines sand, and the required critical incipient velocity V cr . Determine the magnitude of the cross-sectional average velocity , and it is necessary to calibrate the velocity profile and then compare it with the critical incipient velocity. When / V crWhen it is greater than 1, the scouring type is moving bed scouring, otherwise it is clear water scouring.

[0077] Step 3: Based on the judgment result in step 2, the inflow flow rate is increased by increasing the operating power of the water pump so that / V cr greater than or less than 1, respectively, and the flow velocity calibration is performed using the above-mentioned instrument ADV to obtain the flow velocity calibration results under different flushing types;

[0078] Specifically, during the velocity calibration process, three groups of velocity data at each elevation were tested. Each group of tests lasted 45 seconds, and the average value was finally taken as the average velocity value of the group. The three groups of velocity averages obtained from the test were then averaged, and the velocity profile was fitted based on the final average value to eliminate the impact of flow fluctuations as much as possible. Then, a velocity profile along the water depth direction was drawn for velocity calibration, and the distribution of the average cross-sectional velocity and boundary layer thickness was obtained to provide data support for subsequent flushing time calculations.

[0079] Step 4: Based on the flow rate calibration results in step 3, the flushing time to reach static equilibrium is deduced by combining the use of empirical formula prediction and preliminary experimental technical means;

[0080] The flushing time is determined by combining the use of empirical formula predictions with preliminary experiments. The empirical formula can be derived using the following formula.

[0081]

[0082]

[0083]

[0084] Where S(t) is the scour depth that changes with time, S0 is the equilibrium scour depth, t is the scour time, and T s T is the time scale of flushing. * is the dimensionless time scale, D is the horizontal scale of the tube foundation, which is 0.18m, and δ is the boundary layer thickness. The required scouring time is preliminarily deduced, and then a preliminary experiment is carried out to further determine the scouring time to reach a quasi-static equilibrium state.

[0085] Step 5: Based on the scour simulation time determined in step 4, the test plan is obtained by combining key parameters considering various structural conditions, hydrodynamic conditions, and soil conditions.

[0086] Specifically, determine the test parameters to be considered and the parameters to be included in the prediction formula to be derived, generally including: cylinder top height h b , flow angle ψ, flow intensity / Vcr 、water depth h, critical Shields number θ cr 、bed shear stress τ s 、local Shields number θ i 、Froude number Fr, Reynolds number Re.

[0087] Step 6: Based on the preliminary test preparations in Steps 1 - 4, formally conduct the model test by laying model sand on-site, placing the five - cylinder jacket foundation model, and installing the in - place instrument equipment.

[0088] Specifically, complete the landfill and leveling work of the model sand, pre - soak it for 12 h to ensure sediment stability. Prepare the current meter, fill the flume with water to the specified water depth, calibrate the test flow velocity parameters to ensure that the inflow velocity meets the working condition requirements. Prepare the measurement endoscope and topographic survey equipment. After calibration, turn on the water pump to drain water from the flume, and measure the characteristic monitoring points around the model of the cylindrical jacket foundation at regular intervals. Stop the test after the scour reaches equilibrium. Level the site and replace the model until all the test condition data are collected.

[0089] Step 7: Based on the series of model tests carried out in Step 6, obtain the original data of the scour depth and scour range of the five - cylinder jacket foundation model for offshore wind power through numerical analysis and visualization processing techniques.

[0090] Specifically, first, drain the water in the flume to conduct an overall measurement of the topography around the model. After the overall topography is completely measured, take photos for record and complete the site survey. Through the post - processing of photos and point clouds using the 3dfzephyr software, generate a three - dimensional point cloud model containing terrain elevation data, and complete the collation and induction of the recorded scour morphology data. Then, observe the results of the scour depth scale of the measuring points around the five - cylinder jacket foundation model, and record and collate them in a timely manner. Thus, the original data of the scour depth and scour range of the five - cylinder jacket foundation model for offshore wind power are obtained.

[0091] Step 8: Based on the original data of the scour depth of the five - cylinder jacket foundation obtained in Step 7, obtain the scour depth prediction model of the five - cylinder jacket foundation through mathematical derivation and statistical analysis.

[0092] Specifically, first, establish the following scour depth prediction formula.

[0093]

[0094] In the formula, F represents the function formula, and the scour depth h s mainly depends on the geometric dimensions (side cylinder diameter D s 、cylinder top height h b 、cylinder height L), flow conditions (average flow velocity 、critical incipient motion velocity Vcr , the oncoming flow angle water depth h), median grain size of sand particles (d 50 ), etc.

[0095] Then, based on the basic variables, a prediction formula for the scour depth is derived. Selecting V, h, μ as the basic variables, the following calculation formula can be derived:

[0096]

[0097] where g is the acceleration due to gravity, and a0 to a5 are correction coefficients, is the incremental angle of the oncoming flow angle. ρ is the fluid density, and μ is the viscosity coefficient. Since the current test environment is calculated to be turbulent rather than laminar, the influence of the Reynolds number is thus ignored. gh / V 2 can be expressed by the Froude number.

[0098] Secondly, based on logarithmic transformation and the exposed height partition of the five-barrel foundation, a prediction formula for the scour depth is derived. Taking the logarithm of both sides of the above formula, the formula is obtained:

[0099]

[0100]

[0101] In addition, multiple regression fitting is carried out based on the test data. Through a large amount of test data and trial calculation iteration fitting, a prediction formula for the scour depth of the five-barrel jacket foundation can be obtained. And according to the test scenarios and types, the intervals of each parameter are clarified. In the form of:

[0102]

[0103] Finally, based on the above-derived formula, calibration, verification, and further correction are carried out through indoor model test data or on-site monitoring data. The quantitative relationships between the dimensionless scour depth and the key parameters of the scour process (such as the height of the barrel top, flow intensity, water depth, oncoming flow angle, Froude number) are given.

[0104] Step 9: Based on the original data of the scour range of the five-barrel jacket foundation obtained in Step 7, through mathematical derivation and statistical analysis, a prediction model for the scour range of the five-barrel jacket foundation is obtained.

[0105] Specifically, first, a prediction formula for the scour range is derived.

[0106] The maximum size R of the protective scour range can theoretically be calculated from the diameter D of the side barrel s , the height L of the side barrel, the local scour depth h s , and the internal friction angle ψ of the model sand:

[0107] R / Ds = (h s / L) / tan ψ (19)

[0108] Since the tan ψ of the sand used in the test is a constant, the dimensionless maximum scour hole size has a linear relationship with the scour depth, and the slope is 1 / tan ψ.

[0109] Then, modify the scour range prediction formula.

[0110] In fact, the slope of the scour hole profile curve is not continuously smooth, which may lead to an underestimation of the maximum scour hole size in Equation (19). Therefore, a correction coefficient k s and b are further introduced to modify the above formula:

[0111]

[0112] Step 10: Based on the scour depth and scour range prediction formulas obtained in Steps 8 and 9, the scour depth and range prediction formulas for the prototype are obtained through the technical means of scale conversion, so as to realize the prediction of the scour depth and range of the five - connected barrel jacket foundation model of the prototype.

[0113] As Figure 3 - 11 shown, the inventor of the present invention built a circulating flow flume in the Advanced Technology Research Institute of Tianjin University. The flume is 18 m long, 2.4 m wide, and 0.8 m high. Among them, the length of the inlet steady - flow section is 6 m, the length of the test section is 6 m, and the length of the tail - water section is 6 m, and the width is 2.4 m for all. The inlet steady - flow section includes a steady - flow grid and a slope section, which are used to stabilize the water flow and ensure that the water flow enters the sediment pool in the test section evenly and smoothly. A circulating water pump is arranged on the side wall of the flume to generate a constant flow field. The side wall of the flume is made of transparent organic tempered glass plate, through which the flow situation and the change of water depth in the flume can be clearly observed. The test section in the middle of the flume is a sediment pool, which is 6 m long, 2.4 m wide, and 0.15 m high, and is used to place sediment and the barrel - type jacket foundation structure. The tail - water section includes a slope section and a water discharge port, and the water discharge port is arranged on the side of the flume. In order to minimize the influence of the change of water flow pattern caused by the tail - water discharge and the upstream steady - flow as much as possible, the barrel - type jacket structure is arranged in the middle of the test section, at a position 3 m upstream and 3 m downstream of the test section.

[0114] The oncoming flow velocity in the experiment was measured using a Vectrino Doppler current profiler (ADV) from Nortek AS, Norway. The sampling frequency was 200 Hz, and the flow velocity measurement accuracy was ±0.5% of the measured value. The depth measurement of the cylindrical jacket foundation was monitored by two methods. One was to attach a stainless-steel flexible ruler at a characteristic position on one side of the cylinder wall and directly observe it in water. The other was to provide depth data acquisition and output through Astra 2 after the water was drained. The Astra 2 structured light 3D camera was used for terrain photography and scanning. The resolution of the photographed image format was 1600×1200. The depth image data was generated by structured light bathymetry technology, and the depth data of the object in the range of 0.6 m to 8 m could be collected and output. After post-processing the photos and point clouds with 3dfzephyr software, a three-dimensional point cloud model containing terrain elevation data was generated. Considering the site space layout of the experiment in this paper to eliminate the influence of boundary effects as much as possible, the model scale was determined to be 1:100, and the scale conversions are shown in Table 1.

[0115] Table 1 Summary of model scales

[0116]

[0117] The average flow velocity values corresponding to seven different water depths and oncoming flow velocities were measured and are statistically shown in Table 2. For example, when the water depth was 37 cm, the cross-sectional average flow velocity was 26.9 cm / s, and the flow intensity / V cr was less than 1, and at this time it was clear water scour. When the cross-sectional average flow velocity was 38.3 cm / s at a water depth of 37 cm, the flow intensity / V cr was greater than 1, and at this time it was movable bed scour.

[0118] Table 2 Measured cross-sectional average flow velocity

[0119]

[0120] In this embodiment, the above ADV flow velocity device is used to observe the flow velocity in the field area. The ADV is placed directly above the installation position of the test section model. The water pump controller is turned on to generate flow. The height of the ADV gradually increases from bottom to top, and the flow velocity at different water depths is measured. In the flow velocity distribution with h / L = 5.28, within the range of 0 cm to 5 cm from the bed surface, the flow velocity is 20 cm / s to 28 cm / s. Within the range of 5 cm to 30 cm, the flow velocity increases rapidly, and the flow velocity range is 28 cm / s to 36 cm / s. In the flow velocity distribution with h / L = 4.57, within the range of 0 cm to 5 cm from the bed surface, the flow velocity is 26 cm / s to 36 cm / s. Within the range of 5 cm to 30 cm, the flow velocity increases rapidly, and the flow velocity range is 36 cm / s to 40 cm / s. In the flow velocity distribution with h / L = 3.58, within the range of 0 cm to 5 cm from the bed surface, the flow velocity is 24 cm / s to 36 cm / s. Within the range of 5 cm to 25 cm, the flow velocity increases rapidly, and the flow velocity range is 36 cm / s to 42 cm / s. Compared with h / L = 5.28, the flow velocity gradient changes more significantly at h / L = 4.57 and 3.85 within the same elevation, and the flow velocity at the same depth position increases significantly.

[0121] In this embodiment, according to the on-site test situation, the calculation conditions shown in Table 3 are established.

[0122] Table 3 Test Conditions

[0123]

[0124]

[0125] Note: The exposed height of the barrel top is +; the embedded is -.

[0126] After the foregoing steps 1 - step 8, the following five-barrel scour depth prediction formula is obtained. It is applicable to the parameter range of -0.42 ≤ h b / L ≤ 0.42, 3.85 ≤ h / L ≤ 5.28, 0.12 ≤ Fr ≤ 0.17. And the coincidence between the proposed prediction formula and the measured values is compared and verified, and it is found that most of the data points are distributed within the error range of ±20%.

[0127]

[0128] After the foregoing step 9, the five-barrel scour range prediction formula under the same parameter range is obtained. And it is corrected. Taking k s and b can be taken as 2.52 and 0.7, and the final scour range prediction formula is as follows.

[0129]

[0130] Finally, the predicted formula of the scouring range was compared and analyzed with the measured values, and the dimensionless relationship between the scouring range and the scouring depth was summarized. As the scouring depth increases, the scouring range shows an upward trend, presenting a significant positive correlation. Based on the existing test data, this dimensionless relationship was compared and verified, and it was found that most of the data points are distributed within the range of ±20%, indicating that this dimensionless formula can better reflect the relationship between the scouring range and the scouring depth. In addition, the proposed scouring range prediction method was compared with the measured data, and it was also found that most of the data points are distributed within the range of ±20%, and the R 2 is 0.93. Therefore, the proposed scouring range prediction formula is reliable based on the current measured results.

[0131] In this embodiment, the scouring depth prediction and range formula of the five-connected cylinder are deduced and verified through a large amount of test data, which can be used for the rapid prediction of the scouring depth and range of subsequent similar foundation types, avoiding complicated test design and numerical simulation calculation work, and providing a theoretical basis and scientific support for the scouring depth and range prediction of similar foundation types of offshore wind turbines.

[0132] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0133] In this article, specific examples are used to elaborate on the principles and implementation methods of this application. The descriptions of the above embodiments are only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A device for predicting the scour depth and scour range of a five-tube jacket foundation, characterized in that: The five-tube jacket foundation scour depth and scour range prediction device comprises: The simulation end is used to simulate the scouring process of the five-tube jacket foundation model according to the determined test plan to obtain corresponding original scouring data, wherein the original scouring data includes original scouring depth data and original scouring range data; A control end connected to the simulation end, used to derive a model prediction formula according to the original scouring data and the working condition parameters in the test scheme, convert the model prediction formula into a prototype prediction formula by scale conversion, and calculate the scouring depth and scouring range of the five-tube jacket foundation object according to the prototype prediction formula; The analog terminal specifically includes: A water tank to simulate the water flow conditions of a real ocean environment; A five-tube jacket foundation model is arranged in the water tank; The acquisition device is used to acquire the flow velocity data around the five-tube jacket foundation model and the original scour data.

2. The device for predicting scour depth and scour range of a five-tube jacket foundation according to claim 1, characterized in that: The water tank is provided with a water stabilizing section, a first slope, a sand pool, a second slope and a water discharge section in sequence from one end to the other end; The water stabilization section is used to stabilize the water flow; The first slope is used for the inflow to transition to the sand pool; The sand pool is used to hold model sand to simulate the scouring morphology and evolution process around the five-tube jacket foundation model; The second slope is used for outflow transition to the discharge section; The discharge section is used to discharge all outflow into the water pool.

3. A method for predicting the scour depth and scour range of a five-tube jacket foundation, characterized in that: The method for predicting the scour depth and scour range of the foundation of a five-tube jacket is performed by using the device for predicting the scour depth and scour range of the foundation of a five-tube jacket according to any one of claims 1 to 2. The method for predicting the scour depth and scour range of the foundation of a five-tube jacket comprises: According to the determined test plan, the simulation end is used to simulate the scouring process of the five-tube jacket foundation model to obtain the corresponding original scouring data; A model prediction formula is derived based on the original scour data and the operating parameters in the test plan, the model prediction formula is converted into a prototype prediction formula through scale conversion, and the scour depth and scour range of the actual five-tube jacket foundation are calculated based on the prototype prediction formula.

4. The method for predicting the scour depth and scour range of a five-tube jacket foundation according to claim 3 is characterized in that: The process of determining the test plan includes: According to the physical parameters of the five-tube jacket foundation, the scale is determined based on geometric similarity, gravity similarity and motion similarity, wherein the scale includes a geometric scale, a flow rate scale, a flow rate scale and a time scale; Determine the model sand type based on the starting flow rate of the actual parameters of the five-tube jacket foundation; Adjust the inflow flow rate of the simulation end, and use the acquisition equipment to collect flow rate data under different scouring types, wherein the scouring types include moving bed scouring and clean water scouring, and the scouring type is determined based on the flow intensity, and the flow intensity is a variable determined according to the inflow flow rate of the simulation end and the critical starting flow rate of the model sand, and the critical starting flow rate of the model sand is a variable calculated according to the model sand parameters; Calculating the flushing time when static equilibrium is reached according to the flow rate data; The test plan is determined according to the scale, the model sand type and the flushing time.

5. The method for predicting the scour depth and scour range of a five-tube jacket foundation according to claim 3 is characterized in that: The working condition parameters include basic geometric dimension parameters, water flow parameters and model sand parameters of the five-tube jacket foundation model. The basic geometric dimension parameters include the side tube diameter, tube top height and tube height. The water flow parameters include average flow velocity, water depth and incoming flow angle. The model sand parameters include critical starting flow velocity of model sand, internal friction angle of model sand and median particle size of model sand. The model prediction formula includes scour depth prediction formula and scour range prediction formula. The derivation process of the scour depth prediction formula specifically includes: The scour depth prediction formula is established by multivariate regression analysis of the original data of scour depth, the side tube diameter, the tube top height, the tube height, the average flow velocity, the critical starting flow velocity of the model sand, the incoming flow angle, the water depth and the median particle size of the model sand.

6. The method for predicting the scour depth and scour range of a five-tube jacket foundation according to claim 5, characterized in that: The derivation process of the scour range prediction formula specifically includes: Determine a first scour range prediction formula according to the scour range original data, the side tube diameter, the tube height, the scour depth original data and the model sand internal friction angle; The first flushing range prediction formula is corrected using a correction coefficient to obtain the flushing range prediction formula.

7. The method for predicting scour depth and scour range of a five-tube jacket foundation according to claim 5, characterized in that: The expression of the scour depth prediction formula is: Among them, h s is the scouring depth; L is the cylinder height; a0~a5 are the correction coefficients; h b is the height of the cylinder top; is the average flow velocity; V cr is the critical starting velocity of model sand; h is the water depth; is the incoming flow angle; Fr is the Froude number; is the incremental angle of the incoming flow angle.

8. The method for predicting scour depth and scour range of a five-tube jacket foundation according to claim 6, characterized in that: The expression of the scour range prediction formula is: Where R is the maximum size of the protected scour range; D s is the diameter of the side tube; k s and b are correction coefficients; ψ is the internal friction angle of the model sand; a0~a5 are correction coefficients; h b is the height of the cylinder top; L is the cylinder height; is the average flow velocity; V cr is the critical starting velocity of model sand; h is the water depth; is the incoming flow angle; is the incremental angle of the incoming flow angle; Fr is the Froude number.

9. The method for predicting scour depth and scour range of a five-tube jacket foundation according to claim 4, characterized in that: The calculation formula of the critical starting velocity of the model sand is: Among them, V cr is the critical starting velocity of model sand; h is the water depth; d is the median particle size of model sand; γ s is the specific gravity of model sand; γ is the specific gravity of water.

10. The method for predicting scour depth and scour range of a five-tube jacket foundation according to claim 4, characterized in that: The calculation formula of the flushing time is: Where S(t) is the scouring depth that changes with time; S0 is the equilibrium scouring depth; t is the scouring time, T s is the time scale of flushing; T * is the dimensionless time scale; D is the horizontal scale of the side tube foundation; g is the gravitational acceleration; s is the specific gravity; d 50 is the median particle size of the model sand; δ is the boundary layer thickness; θ i is the local Shields number.

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