Test device and test method for simulating multi-direction and multi-angle loading of suction anchor foundation in centrifugal model test

Abstract

The invention discloses a test device for simulating multi-direction and multi-angle loading of a suction anchor foundation in a centrifugal model test, which comprises a test box, a bracket is arranged at the top of the test box, transparent soft clay is arranged at the bottom of the test box, a suction anchor test sample is arranged in the transparent soft clay, and an annular guide rail is connected below the bracket; at least two groups of loading devices are arranged on the annular guide rail, movable fixed pulleys are mounted on the loading devices, anchor points on the suction anchor test sample are connected with steel wire ropes, the other ends of the steel wire ropes penetrate through the fixed pulleys and are connected with loading motors in the loading devices, and the loading devices are connected with the annular guide rail through movable parts. At least three layers of evenly-distributed tracing soil belts different from the soil body in color are arranged in the transparent soft clay under the support, the tracing soil belts are located within the buried depth range of the suction anchor, and the distribution condition of the tracing soil belts is recorded through a miniature camera. According to the invention, the overall displacement deformation condition of the suction anchor under different combination conditions can be more intuitively observed, and important test data is provided for the research of the suction anchor in practical engineering.

Description

Technical Field

[0001] The invention relates to a test device and a test method for simulating multi-directional and multi-angle loading of a suction anchor foundation in a centrifugal model test, and belongs to the field of mechanical performance testing of indoor suction anchor tests. Background Art

[0002] Under the background of the global energy crisis and increasingly serious environmental pollution, the development and utilization of marine energy has become an important development direction. With the accelerated development of marine oil and gas resource exploitation, suction anchor foundation, as a new type of offshore foundation structure, is widely used in marine engineering such as offshore oil and gas, wind power platforms and submarine cables due to its convenient construction and fast construction speed. Suction anchors are widely used, and the force characteristics of suction anchors are varied. The suction anchor foundation is subjected to complex loads, including multi-directional and multi-angle forces generated by environmental factors such as wind, waves, and currents. Its stability and bearing capacity are directly related to the safety and reliable operation of the entire marine engineering structure.

[0003] Previous research and tests on suction anchor foundations have mostly focused on mechanical performance analysis under single-direction loading or simple working conditions. However, the actual marine environment is extremely complex, and single-direction loading tests are difficult to fully reflect the mechanical response of the suction anchor foundation under actual working conditions. Therefore, it is necessary to propose a method to study the situation of non-coplanar loads, which can more realistically simulate the actual marine environment loads and provide key data support for the design and optimization of suction anchor foundations.

[0004] On the other hand, in recent years, the concept of shared suction anchors has been proposed. It is a new type of anchor foundation for floating marine engineering structures. Compared with traditional single-line suction anchors, shared suction anchors can connect multiple offshore structures, reduce the number of suction anchors and save costs. The shared suction anchor points are evenly arranged in the plane at 360°, and some loads can offset each other, reducing the load peak. Its structure with multiple anchor points means that loads in multiple directions act at the same time, and in actual engineering, a slotting effect will occur: floating wind turbines are also prone to grooves in the surrounding soil under the action of long-term wind and wave cycle loads, which will result in changes in the stress performance of the suction anchor foundation. Therefore, it is necessary to study the mechanical properties of suction anchors with multiple anchor points loaded simultaneously for this situation.

[0005] The test is an important method to obtain key data such as the carrying capacity, cumulative displacement, cumulative rotation angle, and overall motion status of the suction anchor in the actual marine environment, which can provide verification basis for theoretical research and numerical simulation. In order to obtain the force performance of the suction anchor / shared suction anchor under multi-directional loads, it is necessary to develop a control system or test device that can realize multi-directional and multi-angle loading in the plane and on the surface. Summary of the invention

[0006] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a test device and a test method for simulating multi-directional and multi-angle loading of a suction anchor foundation in a centrifugal model test, which can more intuitively show the overall displacement and deformation of the suction anchor under different combinations, and provide important test data for the study of suction anchors in actual engineering.

[0007] Technical solution: To solve the above technical problems, the present invention provides a test device for simulating multi-directional and multi-angle loading of a suction anchor foundation in a centrifugal model test, comprising a test box, a bracket is provided on the top of the test box, and transparent soft clay is provided on the bottom. A suction anchor test sample is arranged in the transparent soft clay, and an annular guide rail is connected under the bracket. At least two sets of loading devices are arranged on the annular guide rail. A movable fixed pulley is installed on the loading device. A steel wire rope is connected to the anchor point on the suction anchor test sample, and the other end of the steel wire rope passes through the fixed pulley and is connected to a loading motor in the loading device. The loading device is connected to the annular guide rail through a movable component. A tracer soil belt is arranged in the transparent soft clay directly below the bracket, and at least three layers of uniformly distributed tracer soil belts with different colors from the soil body are arranged. The tracer soil belt is located within the burial depth range of the suction anchor, and the distribution of the tracer soil belt is recorded by a miniature camera.

[0008] Preferably, the loading device comprises a loading rod, on which an axial force meter is mounted, the loading rod is connected to the loading motor via a base, and the top of the loading rod is connected to the movable component.

[0009] Preferably, the movable component includes a stator mounted on an annular guide rail and a mover mounted on the top of the loading rod, the stator is composed of magnets, and the magnets are staggered to form a fixed annular track. A wireless power supply is connected under the mover. When the system uses the wireless power supply to pass current, the magnetic field generated by it will interact with the magnetic field generated by the stator, pushing the mover to move in a straight line or curve along a predetermined track, thereby converting electrical energy into mechanical energy, so that the loading rod moves with the mover.

[0010] Preferably, the mover contains three groups of coils, and the width of the three coils is equal to one-third and one-fourth of the width of the stator.

[0011] Preferably, the annular guide rail is provided with a socket at each fixed distance of the ring, and the mover is provided with an electric latch lock that cooperates with the socket. When the mover needs to be fixed, the electric latch lock on the mover is powered on and inserted into the socket on the annular guide rail.

[0012] Preferably, the loading rod is provided with a slider, the fixed pulley is installed on the slider, the slider is located in the sliding guide rail, a moving motor is installed on the slider, a rack is installed on the sliding guide rail, and the moving motor is engaged with the rack through the gear, thereby driving the slider to move along the sliding guide rail.

[0013] Beneficial effects: The test device and method for simulating multi-directional and multi-angle loading of suction anchor foundations in centrifuge model tests of the present invention. First, the vertical loading angle is manually adjusted and fixed to simulate the loading angle of the suction anchor chain in actual engineering. Then, the horizontal loading angle is controlled by a remote computer to simulate the combined loading of multi-directional winds, waves, and currents in the ocean, and subsequent simulations of combined conditions do not require manual adjustment. Displacement gauges on both sides of the top of the suction anchor can measure the vertical displacement, horizontal displacement, and rotation angle under different angle combination loadings. The axial force gauge on the loading rod can measure the change in the force on the suction anchor. Finally, a micro camera can record the shape of the colored soil strip placed at a certain distance in the transparent soil at the bottom of the suction anchor, aiming to more intuitively observe the overall displacement and deformation of the suction anchor under different combination conditions, providing important test data for the research of suction anchors in actual engineering. Description of the Drawings

[0014] Figure 1 It is a top view of different positions of the loading rod when a single anchor point of the present invention is loaded.

[0015] Figure 2 It is a top view of different positions of the loading rod when multiple anchor points of the present invention are loaded.

[0016] Figure 3 It is a front view of the present invention.

[0017] Figure 4 It is a longitudinal sectional view of the annular guide rail of the present invention.

[0018] Figure 5 It is a partial view of the annular guide rail of the present invention.

[0019] Figure 6 It is a schematic principle diagram of the annular guide rail of the present invention.

[0020] Figure 7 It is a schematic top view of the annular guide rail of the present invention.

[0021] In the figure: support 1, rigid connecting rod 2, annular guide rail 3, loading rod 4, loading motor 5, steel wire 6, movable fixed pulley 7, axial force gauge 8, displacement sensor 9, electric plug lock 10, suction anchor test sample 11, loading anchor point 12, tracer soil strip 13, stator 3.1, rotor 3.2, smooth track 3.3, coil 3.4, plug lock 3.5, jack 3.6, wireless power supply 3.7. Detailed Embodiment

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] As Figures 1 to 7As shown, the test device for simulating multi-directional and multi-angle loading of a suction anchor foundation in a centrifugal model test comprises a bracket 1, a rigid connecting rod 2, a circular guide rail 3, a loading rod 4, a loading motor 5, a steel wire 6, a movable fixed pulley 7, an axial force meter 8, a displacement sensor 9, an electric latch lock 10, a suction anchor test sample 11, a loading anchor point 12, and a tracer soil belt 13.

[0024] Among them, the bracket 1 mainly plays the role of connecting the loading equipment in the test, spanning the entire test box, providing equal and opposite reaction forces to ensure the stability of the test loading system. The rigid connecting rod 2 is mainly used to connect the bracket and the annular guide rail, so that the annular guide rail is firmly fixed under the bracket to facilitate subsequent loading tests. The annular guide rail 3 is mainly designed to change the loading angle of the suction anchor in the horizontal direction, so as to provide a circular motion path for the loading rod, allowing the loading rod to rotate 360° around the central suction anchor model to any position. The loading rod 4 is an important connecting component, and many key components are attached to it to work together. The loading motor 5 on it is connected to the anchor point of the suction anchor model in the middle of the annular guide rail through the steel wire 6, so that the loading motor rotates to drive the steel wire, so that the steel wire is stressed and transmitted to the suction anchor model, simulating the stress of the suction anchor submarine anchor chain. The movable fixed pulley 7 below can move up and down on the loading rod, so that the steel wire that simulates the force of the suction anchor changes the vertical loading angle. The axial force meter 8 on the loading rod and the displacement sensors 9 on both sides of the top of the anchor can monitor the force magnitude and vertical, vertical displacement, and rotation angle on the steel wire connected to the suction anchor. Finally, the distribution of the tracer soil belt is recorded by a micro camera to obtain the overall movement of the suction anchor under load.

[0025] The internal operation system of the circular guide in the system mainly includes the stator 3.1, which is essentially composed of magnets, and the stators are staggered to form a fixed shape track. The magnetic field generated by the stator interacts with the mover to generate electromagnetic force, driving the mover to move along the track, which can provide precise guidance for the mover to ensure the movement trajectory of the mover. The mover 3.2 is the movable part of the motor. The mover contains three sets of coils. When the system uses the wireless power supply 3.7 to pass current, the magnetic field generated by it will interact with the magnetic field generated by the stator, and electromagnetic force will be generated according to the left-hand rule. This force will push the mover to move in a straight line or curve along the artificially predetermined track, thereby converting electrical energy into mechanical energy. A loading rod is embedded under the mover, which allows the loading rod to move with the mover. The smooth track 3.3 is where the mover moves in contact. In order to ensure the accuracy and stability of its movement, the moving surface it contacts must be smooth to ensure minimum friction. The smooth track 3.3 is a dovetail guide rail, and the mover 3.2 is installed on the guide rail slider. The guide rail slider is a dovetail block. Through the cooperation of the dovetail block and the dovetail groove, the mover 3.2 is driven to move along the smooth track 3.3. In addition to being able to generate a magnetic field and interact with the magnetic poles of the stator, the width of the three coils arranged in the mover is equal to one-third of the width of the stator arrangement. Its function is to allow the coil inside the mover to better cover the magnetic field area generated by the stator, enhance the magnetic field coupling efficiency, and then improve the electromagnetic force output and improve the motor efficiency. The electric latch lock 3.5 is designed to ensure the stability of the loading when the loading rod moves on the circular guide rail and stops at any position for loading. A socket 3.6 is designed on the circular guide rail at each fixed distance of the ring. When it is necessary to fix its position, the electric latch lock can immediately extend the latch and insert it into the socket to ensure that its loading will not be affected by structural shaking. In order to ensure the coordination with the movement of its mover, the function of the electric bolt lock is set as follows: when the wireless power supply 3.7 supplies power to it, the bolt does not move, ensuring the smooth movement of its mover; when it is powered off, the electrical energy is converted into mechanical energy, and the bolt is driven to move in a straight line through gear rotation, chain transmission or screw transmission, so as to achieve the extension and retraction of the bolt, so that the bolt can be inserted into the socket 3.6 to clamp the loading rod and thus stable loading can be carried out.

[0026] 1. Vertical loading

[0027] After the suction anchor test model foundation is placed in the center of the test box, one end of the steel wire is connected to the anchor point of the suction anchor loading, and the other end is connected upward to the inside of the loading motor by bypassing the movable fixed pulley. After that, the height of the movable fixed pulley can be adjusted to simulate the vertical loading angle under various working conditions. After the adjustment, the movable fixed pulley is fixed, and the number of coils of the loading motor is controlled on the computer to simulate the size and change of the load.

[0028] 2. Horizontal loading

[0029] After the implementation of vertical loading is completed, the coils in the linear motor mover can be energized in a certain order on the computer according to the structure in the above figure. First, energize the second coil, and the mover will move to the left. Then, energize the first coil, and the mover will continue to move to the left. Next, energize the third coil, and the mover will still move to the left. In this way, a cycle can be carried out. It is also possible to achieve precise movement through a combined energization method. After the electric plug lock on the mover is energized, the plug is pulled out from the jack on the annular guide rail. Then, after the mover is energized, it moves to the position of the horizontal loading angle of the specified working condition under the interaction of the magnetic field. After determining the position of the horizontal angle to be loaded, the current is turned off. The electric plug lock drives the plug to move linearly through methods such as gear rotation, chain drive, or screw drive. The plug extends into the jack of the annular guide rail to lock the mover and also fixes the loading rod on the mover together, facilitating the stable loading of the subsequent loading motor.

[0030] 3. Subsequent automatic loading

[0031] After the combination of horizontal loading and vertical loading is completed, the displacement load conditions corresponding to the combined loading angles can be recorded through the displacement sensor and force sensor on the loading rod. If it is necessary to simulate the next set of working conditions, the operation steps of horizontal loading can be repeated. The mover is energized through the computer, the electric plug lock on the mover is de-energized, the mover moves to the angle loading position of the next working condition, and then the power is turned off. The electric plug lock inserts into the jack to lock the loading rod, so as to continue the loading of the next working condition.

[0032] 4. Multiple anchor points loading simultaneously

[0033] When it is necessary to simulate the situation of multiple anchor points of the shared suction anchor loading simultaneously subsequently, several loading rods can be newly added on the annular guide rail. The same as the single anchor point loading situation, the steel wire is connected to the anchor points of the sample suction anchor in the laboratory and bypasses the movable fixed pulley on the loading rod, and finally is connected to the loading motor. Multiple loading rods can be controlled to move in the remote computer, and loading can be carried out when they move to the specified positions.

[0034] The test device for simulating multi-directional and multi-angle loading of suction anchor foundations in centrifugal model tests of the present invention has the following advantages:

[0035] 1. Angle adjustment innovation: On the basis of traditional vertical loading in a plane, a structure of an annular guide rail is provided, enabling the loading angle of the suction anchor to move beyond the plane, allowing adjustment of different loading positions and actual working conditions, and being able to achieve angle loading tests at any position and any plane of the suction anchor, effectively filling the gap that previous test devices could not or were difficult to conduct such tests.

[0036] 2. Innovation of loading system: The circular guide rail used to adjust the horizontal angle realizes the change of the horizontal angle through electromagnetic induction technology. The stators are staggered in the circular guide rail. Combined with the energized coils in the mover, the movement of the mover can be precisely controlled on the computer, thereby realizing the adjustment of the horizontal loading angle and achieving precise control of the loading angle.

[0037] 3. Innovation in operating system: Compared with the traditional centrifuge test, in which manual operation is required for each loading of a working condition, the operating system proposed in the present invention not only ensures sufficient precision in angle control adjustment, but also facilitates the remote automatic adjustment to simulate the next working condition after the suction anchor foundation working condition test is completed, thereby greatly improving the test efficiency of the suction anchor foundation test.

[0038] 4. Innovation in loading conditions: Compared with previous suction anchors, the shared suction anchor has significant advantages in terms of cost-effectiveness, construction efficiency, and environmental safety. Its multiple anchor points connect multiple offshore floating wind turbines and are subjected to multi-directional wind, wave, and current combined loading conditions, which cannot be simulated by the traditional suction anchor indoor test method. As the shared suction anchor is gradually used on a large scale, its method of simulating multiple anchor point loading is of great significance to actual engineering.

[0039] 5. Simulation of slotting effect: In actual engineering, the anchor-anchor chain-seabed will interact under the combined load of wind, waves and currents. The suction anchor relies on the friction and soil pressure of the seabed soil to provide anchoring force. The seabed soil will deform and redistribute stress under the action of the anchor body, which will affect its strength and stability. The displacement and rotation of the suction anchor under the action of wind, waves and currents will drive the anchor chain to move, and the shape and tension distribution of the anchor chain will change accordingly. At the same time, the tension of the anchor chain will also react to the suction anchor, affecting its movement and stress state. The anchor chain contacts the seabed under tension, generating pressure and friction on the seabed, which may cause local depression or scouring of the seabed surface. Under the action of water flow, the seabed soil around the anchor chain may be washed away, changing the seabed topography, thereby affecting the stability of the suction anchor and the stress of the anchor chain. In summary, the three factors form a complex interactive system. Under this interactive system, floating wind turbines are prone to grooves in the soil around the foundation under the influence of long-term wind, wave and current cyclic loads. The soil loss and stress state changes around the suction anchor foundation caused by the grooves will further lead to changes in the foundation's mechanical properties, which will have an adverse effect on the bearing capacity. For the soil in the experiment, the steel wire buried in the soil and the water in the saturated soil can simulate the interaction of the three factors in actual engineering.

[0040] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A test device for simulating multi-directional and multi-angle loading of a suction anchor foundation in a centrifugal model test, characterized in that: The invention comprises a test box, wherein a bracket is provided on the top of the test box, transparent soft clay is provided on the bottom, a suction anchor test sample is arranged in the transparent soft clay, an annular guide rail is connected under the bracket, at least two groups of loading devices are arranged on the annular guide rail, a movable fixed pulley is installed on the loading device, a steel wire rope is connected to the anchor point on the suction anchor test sample, the other end of the steel wire rope passes through the fixed pulley and is connected to the loading motor in the loading device, the loading device is connected to the annular guide rail through a movable component, a tracer soil belt is arranged in the transparent soft clay directly below the bracket, at least three layers of tracer soil belts evenly distributed and different in color from the soil body are arranged, the tracer soil belts are located within the burial depth range of the suction anchor, and the distribution of the tracer soil belts is recorded by a miniature camera.

2. The test device for simulating multi-directional and multi-angle loading of suction anchor foundation in centrifugal model test according to claim 1 is characterized in that: The loading device comprises a loading rod, on which an axial force meter is installed. The loading rod is connected to a loading motor through a base, and the top of the loading rod is connected to a movable component.

3. The test device for simulating multi-directional and multi-angle loading of suction anchor foundation in centrifugal model test according to claim 1 or 2, characterized in that: The movable component includes a stator installed on a circular guide rail and a mover installed on the top of the loading rod. The stator is composed of magnets, which are staggered to form a fixed circular track. A wireless power supply is connected under the mover. When the system uses the wireless power supply to pass current, the magnetic field generated by it will interact with the magnetic field generated by the stator, pushing the mover to move in a straight line or curve along a predetermined track, thereby converting electrical energy into mechanical energy, so that the loading rod moves with the mover.

4. The test device for simulating multi-directional and multi-angle loading of suction anchor foundation in centrifugal model test according to claim 3 is characterized in that: The mover contains three groups of coils, and the width of the three coils is equal to one-third and one-fourth of the width of the stator.

5. The test device for simulating multi-directional and multi-angle loading of suction anchor foundation in centrifugal model test according to claim 3 is characterized in that: The annular guide rail is provided with a socket at each fixed distance of the ring, and the mover is provided with an electric latch lock matched with the socket. When the mover needs to be fixed, the electric latch lock on the mover is powered on and inserted into the socket on the annular guide rail.

6. The test device for simulating multi-directional and multi-angle loading of suction anchor foundation in centrifugal model test according to claim 1 or 2, characterized in that: The loading rod is provided with a slider, a fixed pulley is installed on the slider, the slider is located in the sliding guide rail, a moving motor is installed on the slider, a rack is installed on the sliding guide rail, and the moving motor is engaged with the rack through a gear, thereby driving the slider to move along the sliding guide rail.

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