A device for simulating suction bucket foundation penetration in centrifugal model tests

Abstract

The present invention provides a device for simulating the penetration of a suction bucket foundation in a centrifugal model test, comprising a model box, a suction bucket model disposed therein, the suction bucket model comprising a suction bucket and a connecting rod, a penetration device disposed on the top of the model box, the top end of the connecting rod being movably connected to the penetration device; the suction bucket being connected to a vacuum system, soil being disposed at the bottom of the suction bucket, and water being disposed at the top of the soil; the penetration device comprising a limiting groove located outside the model box, a driving rod being disposed within the limiting groove, the driving rod being connected to an electromagnetic adsorption device located within the model box after passing through the top of the model box, a guide cover being connected below the electromagnetic adsorption device, and the top end of the connecting rod being located within the guide cover. By providing the penetration device, displacement deviations during the penetration process can be dynamically corrected, enabling the device of the present invention to continuously perform tests in a centrifugal state.

Description

Technical Field

[0001] The invention relates to the field of offshore wind power foundation structures, in particular to a device for simulating suction bucket foundation penetration in a centrifugal model test. Background Art

[0002] Wind energy, a clean, renewable energy source, is widely distributed and holds enormous development potential. Wind power generation is currently a key form of wind energy utilization. In recent years, my country has rapidly accelerated the construction of offshore wind farms, with an estimated 8 to 10 GW of new offshore wind power grid-connected capacity expected between 2021 and 2025. Offshore wind farm construction requires significant investment, and cost control has always been a key challenge in the offshore wind power industry. Turbine foundations account for approximately 20% to 30% of the total project cost. Compared to conventional large-diameter monopile foundations, suction bucket foundations offer a cost-effective alternative suitable for soft clay and sandy soils. However, unlike large-diameter monopile foundations, suction bucket foundations can lead to excessive soil surface bulging within the bucket due to suction penetration, creating a "soil plug." The suction applied in non-cohesive soils can further induce seepage within and outside the bucket, exacerbating the soil plug. Numerous studies have shown that during the combined process of deadweight and suction penetration, approximately 30% to 50% of the soil displaced by the bucket wall enters the bucket. The soil squeezing effect and suction during penetration cause irreversible plastic deformation in the soil, further altering pore water pressure and the effective stress in the soil, which in turn affects the mechanical properties of the suction bucket foundation. However, these results are mostly based on 1g laboratory model tests, where the stress generated by deadweight is relatively low, and may differ from the soil plugging phenomenon and soil stress variation under real-world conditions. A more realistic representation of soil plugging and soil stress-strain behavior can be obtained through vacuum pump testing. However, conventional centrifugal model tests have not yet effectively implemented suction bucket penetration. The challenge lies in simulating penetration by placing the foundation on the soil surface and controlling verticality without stopping the vacuum pump. Therefore, how to effectively implement penetration in centrifuge model tests, monitor and record the changes in foundation and soil properties during the penetration process, and then use this to analyze the impact of the penetration effect on the static and dynamic working characteristics of the suction bucket in actual engineering is of great significance to engineering practice.

[0003] A Chinese patent application (publication number: CN114894510A) discloses a "vacuum pump test model for the installation and operation process of a suction bucket foundation." This test model has the following problems when used:

[0004] 1. The test model uses a counterweight structure, which has poor stability and usability during the continuous rotation of the centrifuge, thus affecting the test results;

[0005] 2. This test model can only ensure the verticality of the suction bucket sinking in a non-centrifugal state, but cannot be guaranteed in a centrifugal state, and therefore cannot be tested under a greater centrifugal force;

[0006] 3. This test model cannot directly observe the displacement of the suction bucket and the deformation of the soil inside and outside the bucket, and the operation is complicated. Summary of the Invention

[0007] Purpose of the invention: In order to solve the above technical problems, the present invention provides a device for simulating the penetration of a suction bucket foundation in a centrifugal model test.

[0008] Technical solution: The present invention provides a device for simulating suction bucket foundation penetration in a centrifugal model test, comprising a model box, a suction bucket model disposed within the model box, the suction bucket model comprising a suction bucket connected to a vacuum system, soil disposed below the suction bucket, and water disposed above the soil; a penetration device disposed on the top of the model box;

[0009] The suction barrel includes a semicircular side wall, a semicircular top plate is provided at the upper end of the side wall, and the top plate is connected to the penetration device via a connecting rod; the top plate and the side wall form a semicircular barrel-shaped structure with open sides and a bottom, and a sealing structure is provided on the upper side and the side of the side opening; the interior of the model box is divided into a first area and a second area by tempered glass, and the suction barrel model and the penetration device are arranged in the first area; the side of the suction barrel contacts one side of the tempered glass, and the contact part is sealed by the sealing structure.

[0010] Furthermore, the penetration device includes a bracket located at the top of the model box, a guide rail is provided on the bracket, a driving rod is provided in the guide rail, the driving rod passes through the top of the model box and is connected to the electromagnetic adsorption device located in the model box, a guide cover is connected below the electromagnetic adsorption device, and the top of the connecting rod is located in the guide cover; the guide rail is connected to a horizontal driving device that can cause it to move laterally, and the top of the driving rod is connected to a vertical driving device.

[0011] Furthermore, a long strip chute is provided at the portion of the model box through which the driving rod passes, and the guide rail extends into the chute and can move within the chute.

[0012] Furthermore, the transverse driving device includes a transverse transmission rack connected to the guide rail, and a gear connected to the bracket and meshing with the transverse transmission rack, and the gear is connected to the driving device.

[0013] Furthermore, a limiting mass block is provided at the top end of the connecting rod. The limiting mass block is located in the guide cover and is limited by the inner wall of the guide cover, and can move up and down along the inner wall of the guide cover.

[0014] Furthermore, a plurality of sensors are arranged in the soil, with the position after the suction bucket is completely sunk into the soil being used as a reference, and the plurality of sensors are distributed in the soil inside and outside the side wall of the suction bucket.

[0015] Furthermore, at least three layers of evenly distributed tracer soil belts with different colors from the soil are provided in the soil body. The tracer soil belts are located within a burial depth twice that of the suction bucket and are used to display soil deformation.

[0016] Furthermore, a plurality of laser displacement meters are provided in the model box, and the laser displacement meters are used to monitor the displacement of the suction bucket in various directions.

[0017] Furthermore, the vacuum system includes a conduit with one end connected to the suction bucket, the other end of the conduit is connected to a water-gas conversion device, and the water-gas conversion device is connected to a vacuum pump.

[0018] Furthermore, a camera is provided in the second area.

[0019] Beneficial effects: The device for simulating the penetration of a suction bucket foundation in a centrifugal model test of the present invention has the following advantages:

[0020] Beneficial effects:

[0021] 1. The present invention does not have a counterweight structure, which ensures high stability and availability during the continuous rotation of the centrifuge, ensuring accurate test results;

[0022] 2. By setting up transparent tempered glass and camera, the test status can be observed in real time under centrifugal state;

[0023] 3. By providing a penetration device, the displacement deviation during the penetration process can be dynamically corrected, so that the device of the present invention can continue to perform tests in a centrifugal state;

[0024] 4. The soil pressure gauge and piezometer record the soil characteristics and displacement state changes around the suction bucket, realize the suction bucket penetration simulation and penetration effect analysis, and provide a theoretical basis for the subsequent static and dynamic working characteristics analysis of the suction bucket foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention;

[0026] Figure 2 for Figure 1 AA sectional view;

[0027] Figure 3 It is a schematic diagram of the local structure of the penetration device;

[0028] Figure 4 for Figure 3 AA sectional view;

[0029] Figure 5 This is a structural diagram of the suction bucket model. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0031] like Figure 1 、 Figure 2 and Figure 5 As shown, the present invention includes a model box 1, in which a suction bucket model is arranged. The suction bucket model includes a suction bucket 2 and a connecting rod 3. A penetration device 4 is arranged on the top of the model box 1, and the top end of the connecting rod 3 is movably connected to the penetration device 4. The suction bucket 2 is connected to the vacuum system 30, and a soil body 5 is arranged at the bottom of the suction bucket, and a water body 6 is arranged at the top of the soil body 5. A plurality of sensors 51 are arranged in the soil body 5. With the position after the suction bucket is completely sunk into the soil body as a reference, the plurality of sensors 51 are distributed in the soil body inside and outside the side walls of the suction bucket. In addition, at least three layers of tracer soil strips 52 of different colors from the soil body are arranged in the soil body 5. The tracer soil strips 52 are used to display the deformation of the soil body. A plurality of laser displacement meters 101 are arranged in the model box 1. The laser displacement meters 101 are used to monitor the displacement of the suction bucket in various directions. A T-type penetrometer 53 is also provided in the soil 5 , and the sensor 51 is a soil pressure gauge and / or a piezometer. The sensor 51 can detect the changes in the surrounding soil pressure and / or pore water pressure during the penetration of the suction bucket 2 .

[0032] The suction barrel 2 includes a semicircular sidewall 21, with a semicircular top plate 22 positioned above the sidewall 21. The top plate 22 is connected to the penetration device 4 via a connecting rod 3. The top plate 22 and the sidewall 21 form a semicircular barrel-shaped structure with open sides and a bottom. Sealing structures 201, which can be rubber sealing strips, are positioned above and on the sides of the side openings. The interior of the model box 1 is divided into a first area and a second area by tempered glass 10. The suction barrel model and the penetration device are positioned within the first area. The side of the suction barrel contacts one side of the tempered glass, and the sealing structure seals the contact area. The sealing structure 201 prevents water within the model box 1 from entering the suction barrel 2 through the gap between the suction barrel 2 and the tempered glass 10 during the penetration test. A camera 100 is positioned within the second area to facilitate real-time observation of the suction barrel penetration.

[0033] The vacuum system 30 includes a conduit 31 connected to the suction bucket 2 at one end, and the other end of the conduit 31 is connected to a water-gas conversion device 32, and the water-gas conversion device 32 is connected to a vacuum pump 33. Specifically, the vacuum system 30 can select other existing devices or systems that can achieve the same functions as the present invention. The vacuum pump 33 is used to extract vacuum to form negative pressure. The vacuum system also includes common vacuum system devices such as a vacuum control valve and a vacuum gauge. The vacuum control valve is used to adjust the size of the suction force, and the vacuum gauge monitors the actual size of the negative pressure. The water-gas conversion device is used to convert the negative pressure generated by the vacuum pump into the sinking negative pressure of the suction bucket, and at the same time, it receives the water extracted by vacuum, and is used to relieve pressure after the test.

[0034] like Figure 3 As shown, the penetration device 4 includes a bracket 41 located at the top of the mold box 1. A guide rail 42 is provided on the bracket 41, and a drive rod 43 is disposed within the guide rail 42. The drive rod 43 passes through the top of the mold box 1 and connects to an electromagnetic adsorption device 7 located within the mold box. A guide hood 8 is connected below the electromagnetic adsorption device 7. The top end of the connecting rod 3 is located within the guide hood. The guide rail 42 is connected to a lateral drive device that enables lateral displacement of the drive rod 43, and the top end of the drive rod 43 is connected to a vertical drive device. Specifically, the lateral drive device includes a lateral transmission rack 44 connected to the guide rail 42, and a gear 45 connected to the bracket 41 and meshing with the lateral transmission rack 44. This gear 45 is connected to the drive device, which can be an electric motor. The vertical drive device connected to the top end of the drive rod 43 can generally be a hydraulic drive device or other existing device or structure capable of pushing or pulling the drive rod 43. A limit mass 301 is provided at the top end of the connecting rod 3. The limit mass 301 is located within the guide hood 8 and is restrained by the inner wall of the guide hood 8, enabling up and down movement along the inner wall of the guide hood 8.

[0035] like Figure 4 As shown, a long strip chute 11 is provided at the portion of the model box 1 through which the driving rod 43 passes, and the guide rail 42 extends into the chute 11 and can move within the chute 11 .

[0036] When conducting a simulation test, the device of the present invention is placed on a centrifuge and the centrifuge is started to run to the centrifugal acceleration designed for the test (which can be 50G). A penetration test is then carried out using a T-type probe 53 to measure the penetration resistance of the soft clay and estimate the penetration force. The penetration device 4 above the control bracket 41 is controlled to lower the suction bucket model adsorbed on the electromagnetic adsorption device along the drive rod 43. After the bottom of the suction bucket is lowered to the soil surface, the electromagnetic adsorption device is disconnected, allowing the foundation to sink under its own weight first. The vacuum system 30 is then turned on to simulate negative pressure penetration. To ensure verticality during the self-weight and suction penetration process, a laser displacement meter is used to monitor the displacement and angular changes of the suction bucket 2 during the negative pressure penetration process. Smaller angular and horizontal displacements can be limited by the side walls of the rectangular guide cover on the penetration device 4. When the data recorded by the laser displacement meter shows a large displacement deviation, the penetration device 4 can be corrected by the transverse drive device and the longitudinal drive device.

[0037] During the penetration process, a miniature high-definition camera 100 captures real-time images of the continuous displacement changes of the soil and suction bucket. Particle image velocimetry (PIV) is used to capture moving soil particles and segment them into image pixels for analysis. This allows the displacement trends of the soil inside and outside the suction bucket to be determined as the penetration progresses. To facilitate observation of soil deformation around the suction bucket foundation, the soil is dyed with carbon powder to form dark stripes. Simultaneously, soil pressure gauges, pore pressure gauges, and laser displacement meters are deployed to monitor and record the horizontal and depth variations of soil pressure and pore water pressure, the suction bucket foundation penetration velocity, and the vertical and horizontal displacements.

Claims

1. A device for simulating suction bucket foundation penetration in a centrifugal model test, comprising a model box, a suction bucket model disposed within the model box, the suction bucket model including a suction bucket connected to a vacuum system, soil disposed below the suction bucket, and water disposed above the soil; a penetration device disposed on top of the model box; and characterized in that: The suction barrel includes a semicircular side wall, a semicircular top plate is provided at the upper end of the side wall, and the top plate is connected to the penetration device via a connecting rod; the top plate and the side wall form a semicircular barrel-shaped structure with open sides and a bottom, and a sealing structure is provided on the upper side and the side of the side opening; the interior of the model box is divided into a first area and a second area by tempered glass, and the suction barrel model and the penetration device are arranged in the first area; the side of the suction barrel contacts one side of the tempered glass, and the contact part is sealed by the sealing structure.

2. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 1, characterized in that: The penetration device includes a bracket located at the top of the model box, a guide rail is provided on the bracket, a driving rod is provided in the guide rail, the driving rod passes through the top of the model box and is connected to an electromagnetic adsorption device located in the model box, a guide cover is connected below the electromagnetic adsorption device, and the top of the connecting rod is located in the guide cover; the guide rail is connected to a horizontal driving device that can cause it to move laterally, and the top of the driving rod is connected to a vertical driving device.

3. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 2, characterized in that: A long strip chute is provided on the model box at a position through which the driving rod passes, and the guide rail extends into the chute and can move in the chute.

4. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 2, characterized in that: The transverse driving device includes a transverse transmission rack connected to the guide rail, and a gear connected to the bracket and meshing with the transverse transmission rack, and the gear is connected to the driving device.

5. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 2, characterized in that: A limiting mass block is provided at the top end of the connecting rod. The limiting mass block is located in the guide cover and is limited by the inner wall of the guide cover, and can move up and down along the inner wall of the guide cover.

6. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 1, characterized in that: A plurality of sensors are arranged in the soil, with the position of the suction bucket completely sunk into the soil being used as a reference, and the plurality of sensors are distributed in the soil inside and outside the side wall of the suction bucket.

7. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 1, characterized in that: At least three layers of evenly distributed tracer soil belts with different colors from the soil are provided in the soil body. The tracer soil belts are located within a burial depth twice that of the suction bucket and are used to display soil deformation.

8. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 1, characterized in that: A plurality of laser displacement meters are arranged in the model box, and the laser displacement meters are used to monitor the displacement of the suction bucket in various directions.

9. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 1, characterized in that: The vacuum system includes a conduit with one end connected to the suction bucket, the other end of the conduit is connected to a water-gas conversion device, and the water-gas conversion device is connected to a vacuum pump.

10. The device for simulating suction bucket foundation penetration in a centrifugal model test according to claim 4, characterized in that: A camera is disposed in the second area.

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