A hypergravity centrifuge test and observation system suitable for suction anchors

Abstract

This invention discloses a centrifuge testing and observation system suitable for suction anchors. The system includes a test foundation and a suction anchor model housed inside a model box, a pulley support assembly on the upper part of the model box, a camera support, a laser displacement measurement assembly, a horizontal loading mechanism, and a support frame. The horizontal loading mechanism connects to the anchor point of the suction anchor model via rigging and the pulley guide frame, thereby achieving model loading. This experimental device has wide applicability, is not limited to any type of test foundation, and the height and position of various support components can be adjusted at any time according to the soil height of the model box and the required loading angle. The system is equipped with a T-bar or CPTu, a laser displacement sensor, a pore pressure gauge, and an accelerometer, enabling precise and diverse measurements of soil strength, soil settlement, pore pressure within the test foundation soil, and model movement. It can efficiently and conveniently observe the dynamic response of the suction anchor and the response of the test foundation soil.

Description

Technical Field

[0001] This invention belongs to the field of marine anchoring foundation technology, specifically relating to a centrifuge testing and observation system suitable for suction anchors. Background Technology

[0002] Floating platforms typically require a mooring system consisting of mooring lines and mooring foundations for positioning, with suction anchors being the most widely used type of anchorage foundation. A suction anchor is a large, thin-walled cylindrical steel structure with an open bottom and a closed top equipped with a pumping port. It features precise positioning, cost-effectiveness, ease of construction, and reusability, providing substantial vertical loads and exhibiting good applicability in sandy, clay, or layered soil seabeds.

[0003] The harsh environment of the deep ocean, under extreme sea conditions, causes floating platforms to exhibit complex six-degree-of-freedom spatial motion characteristics, such as wave frequency oscillations and slow low-frequency drift. Consequently, the connecting mooring lines also undergo cyclical changes in different states, including slack, tension, dynamic bottoming, and rapid lifting. This leads to dynamic evolution of the magnitude and angle of the anchor chain tension load acting on the anchorage foundation anchorhole. Furthermore, to reduce construction and installation costs and achieve efficient mooring, deep-water mooring has gradually abandoned traditional catenary mooring systems, instead adopting tensioned or semi-tensioned mooring systems using multi-component mooring lines (steel chains, metal cables, and synthetic fiber ropes, etc.). In this case, the angle of the load acting on the suction anchor generally exceeds 30° above the seabed, making load transfer more complex. Therefore, developing an efficient and reliable suction anchor load-bearing capacity testing system and studying the catastrophe mechanism of suction anchors under complex loads are of significant engineering application value for the safety and economy of anchoring systems, and are also key to the optimized design and operation and maintenance of large-scale offshore floating platforms in deep waters. Summary of the Invention

[0004] To address the problems existing in the background technology, this invention proposes a centrifuge testing and observation system suitable for suction anchors. The entire system can conveniently and efficiently adjust the loading angle of the suction anchor, realize the loading process of the suction anchor foundation in a real marine environment, and can monitor the anchor chain stress state, the three-dimensional displacement and rotation of the suction anchor, soil settlement, and water pressure state in real time during the loading process.

[0005] A centrifuge testing and observation system for suction anchors is disclosed. The entire system is placed on the centrifuge basket and includes a model box, a suction anchor model, rigging, a vertical loading mechanism, a horizontal loading mechanism, a pulley support assembly, a camera bracket, and a laser displacement measurement assembly. The model box contains a test foundation, and the suction anchor model is placed within the test foundation. One end of the rigging is connected to the suction anchor model, and the other end is connected to the horizontal loading mechanism. The vertical loading mechanism is used for vertical loading tests of the soil strength of the test foundation. The horizontal loading mechanism is used to apply static and cyclic loads to the suction anchor model. The pulley support assembly is used to change the force direction of the rigging. The camera bracket is used to monitor the loading state of the suction anchor model in real time, and the laser displacement measurement assembly is used to monitor the displacement of the suction anchor model in real time.

[0006] Furthermore, the suction anchor model is equipped with a bottom pore pressure gauge bracket, threaded mounting holes, an accelerometer mounting slot, a model anchor point, a bottom pore pressure gauge, a top pore pressure gauge, and an accelerometer. The suction anchor model is a cylindrical hollow structure. The bottom pore pressure gauge bracket is fixed to the bottom inner side of the suction anchor model for mounting the bottom pore pressure gauge. The threaded mounting holes are located at the top of the suction anchor model and include: a water pumping valve hole, a pore pressure gauge mounting hole, a pore pressure gauge outlet hole, and a drainage hole. The water pumping valve hole is used for installing an external water pumping device on the suction anchor model. The pore pressure gauge mounting hole is used for mounting the top pore pressure gauge. The pore pressure gauge outlet hole is used for the pore pressure gauge to exit. The drainage hole is used for drainage during installation and is sealed after completion. The accelerometer mounting slot is located at the top of the suction anchor model for mounting an accelerometer. The accelerometer is used to measure the motion response of the suction anchor model during loading. The model anchor point is the suction anchor loading point, located on the outer wall of the suction anchor model, and is used to connect to the rigging.

[0007] Furthermore, the rigging is one or more of anchor chains and wire ropes.

[0008] Furthermore, the vertical loading mechanism includes a first servo motor, a first right-angle reducer, a first top plate, a sensor connector, a transition push plate, a first bottom plate, a guide rod, a guide shaft, a first ball screw, and a probe rod; The first base plate is fixed to the model box. The first top plate is fixedly connected to the first base plate via a guide rod. The first servo motor and the first right-angle reducer are fixed to the first top plate. The output end of the first servo motor is connected to the input end of the first right-angle reducer. One end of the first ball screw passes through the first top plate and is connected to the output end of the first right-angle reducer. The transition push plate is located between the first top plate and the first base plate, and is sleeved on the guide rod and threadedly connected to the first ball screw. The rotation of the first ball screw drives the transition push plate to move. The sensor connecting seat is fixed to the transition push plate. One end of the probe rod is connected to the sensor connecting seat, and the other end is equipped with a probe for detecting soil strength. The guide shaft is used to fix the signal line of the probe.

[0009] Furthermore, the horizontal loading mechanism includes a second servo motor, a second right-angle reducer, a second ball screw, a guide rod, a second base plate, a frame, a load sensor, a slide plate, and a loading head; The slide plate is fixed to the model box, the second base plate is fixed to the slide plate, the second servo motor and the second right-angle reducer are fixed on the second base plate, the output end of the second servo motor is connected to the input end of the second right-angle reducer, one end of the second ball screw is connected to the output end of the second right-angle reducer, and the other end is movably connected to the frame, one end of the guide rod is sleeved on the second threaded screw, the second threaded screw rotates, pushing the guide rod assembly to move, the load sensor and the loading head are fixed to the other end of the guide rod, and the loading head is fixedly connected to the end of the rigging.

[0010] Furthermore, the pulley support assembly includes a first fixed pulley, a second fixed pulley, two fixed pulley blocks, a first fixed pulley mounting frame, a second fixed pulley mounting frame, four slide rail columns, two third base plates, a third top plate, a first beam plate, a second beam plate, and two movable frames; The third base plate is symmetrically fixed to the top of the model box. Slide columns are fixed to the four corners of the third top plate, and the slide columns are fixed to the third base plate. The two ends of the first beam plate are connected to the slide columns on both sides. Movable frames are movably connected to the slide columns. The two ends of the second beam plate are connected to the movable frames on both sides. The first fixed pulley mounting frame is fixed to the first beam plate, and the first fixed pulley is mounted on the first fixed pulley mounting frame. The second fixed pulley mounting frame is fixed to the second beam plate, and the second fixed pulley is mounted on the second fixed pulley mounting frame. Fixed pulley blocks are used to fix the first and second fixed pulleys respectively. The pulley bracket assembly as a whole serves as a guide device for the rigging, used to change the direction of force on the rigging.

[0011] Furthermore, the camera bracket includes a camera, a camera assembly, a support rod, an upright plate, a hanging beam, and a fourth base plate. The camera is connected to a computer in the control room via a network cable through the optical transceiver of the centrifuge. The computer monitors the loading status of the suction anchor model in real time. The camera assembly is used to mount the camera and is slidably connected to the hanging beam. The hanging beam has a slide rail for the camera assembly to slide. Both ends of the hanging beam are slidably connected to the upright plate. One end of the support rod is connected to the hanging beam, and the other end is connected to the fourth base plate, which is used to support the hanging beam to be adjusted to different heights. The fourth base plate is fixed to the top of the model box and is fixedly connected to the upright plate.

[0012] Furthermore, the laser displacement measurement assembly includes a positioning beam, a lead screw, a displacement sensor connecting sleeve, a laser displacement sensor, and a displacement sensor connecting plate; the positioning beam is fixed on the model box and has a slide rail with a hollow center, one end of the lead screw is fixed on the slide rail, and the displacement sensor is connected to the other end of the lead screw in sequence through the displacement sensor connecting plate and the displacement sensor connecting sleeve.

[0013] A method for testing and observing a centrifuge based on any of the above-described suction anchors for use with gravity includes the following steps: Step 1: Determine the installation position and angle of the suction anchor model and prepare the test foundation; Step 2: After the test foundation is prepared, install the pulley support assembly, camera support, laser displacement measurement assembly, vertical loading mechanism, horizontal loading mechanism and horizontal loading mechanism support frame one by one, and fix them to the model box with bolts according to the marked installation position; Step 3: Connect the suction anchor model to the loading head of the horizontal loading mechanism via a rigging system and pulley support assembly; adjust the position and height of the pulley support assembly, and tension the rigging loading angle to the design value; Step 4: Connect all sensors in the system to the centrifuge's data acquisition system, arrange the light source, and connect the camera; connect the vertical loading mechanism and the horizontal loading mechanism controller.

[0014] Step 5: Start the centrifuge. For sandy soil foundations, start the vertical loading mechanism to test the soil strength. Step 6: After the soil strength test is completed, start the horizontal loading mechanism to pull the rigging and apply static or cyclic load to the suction anchor model according to the preset working conditions; record the sensor data according to the centrifuge data until the horizontal loading mechanism shrinks to its minimum.

[0015] Furthermore, in step 1, for sandy soil foundations, the speed of sand falling is controlled according to the preset funnel opening and drop distance to obtain a sandy seabed with a set density; for clay soil foundations, drainage pipes and sand cushions are laid at the bottom of the model box, and mud is prepared and poured into the model box. In step 2, for sandy soil foundations, a CPTu probe is installed in the vertical loading mechanism; for clay soil foundations, a T-bar probe is installed in the vertical loading mechanism. In step 5, the soil strength is tested: for sandy soil foundations, the vertical loading mechanism is activated to test the soil strength using CPTu; for clay soil foundations, after the pore pressure dissipates from the consolidation test foundation, the vertical loading mechanism is activated to test the soil strength using T-bar.

[0016] The beneficial effects of this invention are: (1) This invention is also applicable to suction anchor loading tests on sandy clay foundation types. Since the pulley support assembly can adjust the pulley height, there is no need to consider the influence of the soil height inside the model box. The loading angle of the model can be adjusted arbitrarily, and static and cyclic loads can be applied to simulate real marine environmental loads to the greatest extent. After the invention is installed, all other operations can be performed on the centrifuge industrial computer without stopping the machine for adjustments, which is very convenient.

[0017] (2) The observation system of this invention contains multiple types of sensors, which improves the observation dimension of the suction anchor from two-dimensional to three-dimensional. It can observe the multi-degree-of-freedom motion of the suction anchor and the soil state in real time, thereby effectively analyzing the failure mode and failure mechanism of the suction anchor model. Attached Figure Description

[0018] Figure 1 This is a front view of a centrifuge test and observation system for suction anchors according to an embodiment of the present invention.

[0019] Figure 2 This is a top view of a centrifuge test and observation system for suction anchors according to an embodiment of the present invention.

[0020] Figure 3 This is a three-dimensional schematic diagram of a centrifuge test and observation system for suction anchors according to an embodiment of the present invention.

[0021] Figure 4 This is a front view of a suction anchor model according to an embodiment of the present invention.

[0022] Figure 5 This is a top view of a suction anchor model according to an embodiment of the present invention.

[0023] Figure 6 This is a three-dimensional schematic diagram of a suction anchor model according to an embodiment of the present invention.

[0024] Figure 7 This is a front view of a pulley bracket assembly according to an embodiment of the present invention.

[0025] Figure 8 This is a side view of a pulley bracket assembly according to an embodiment of the present invention.

[0026] Figure 9 This is a three-dimensional schematic diagram of a pulley bracket assembly according to an embodiment of the present invention.

[0027] Figure 10 This is a front view of a camera bracket assembly according to an embodiment of the present invention.

[0028] Figure 11 This is a top view of a camera bracket assembly according to an embodiment of the present invention.

[0029] Figure 12 This is a three-dimensional schematic diagram of a camera bracket assembly according to an embodiment of the present invention.

[0030] Figure 13 This is a front view of a laser displacement measurement component according to an embodiment of the present invention.

[0031] Figure 14 This is a three-dimensional schematic diagram of a laser displacement measurement component according to an embodiment of the present invention.

[0032] Figure 15 This is a front view of a horizontal loading mechanism component according to an embodiment of the present invention.

[0033] Figure 16 This is a front view of a vertical loading mechanism component according to an embodiment of the present invention.

[0034] Figure 17 This is a top view of a vertical loading mechanism component according to an embodiment of the present invention.

[0035] Figure 18 This is a three-dimensional layout diagram of the vertical loading mechanism components according to an embodiment of the present invention.

[0036] In the diagram: 1 is the test foundation, 2 is the suction anchor model, 3 is the pulley support assembly, 4 is the camera support, 5 is the laser displacement measurement assembly, 6 is the horizontal loading mechanism, 7 is the horizontal loading mechanism support frame, 8 is the vertical loading mechanism, 9 is the threaded mounting hole, 9a is the water pumping valve hole, 9b is the orifice pressure gauge mounting hole, 9c is the orifice pressure gauge outlet hole, 9d is the drainage hole, 10 is the accelerometer mounting slot, 11 is the bottom orifice pressure gauge support, 12 is the model anchor point, 13 is the rigging, 14 is the buckle, 15 is the first fixed pulley, 16 is the fixed pulley plug, 17 is the first fixed pulley mounting frame, 18 is the slide column, 19 is the third base plate, 20 is the third top plate, 21 is the first beam plate, 22 is the movable frame, 23 is the camera assembly, 24 is the strut, 25 is the upright plate, 26 is the... 27 is the lifting beam, 28 is the fourth base plate, 29 is the pad plate, 30 is the positioning crossbeam, 31 is the lead screw, 32 is the displacement sensor connecting sleeve, 33 is the laser displacement sensor, 34 is the displacement sensor connecting plate, 35 is the second servo motor, 36 is the second right-angle reducer, 37 is the second ball screw, 38 is the guide rod, 39 is the second base plate, 40 is the frame, 41 is the load sensor, 42 is the loading head, 43 is the slide plate, 44 is the first servo motor, 45 is the first right-angle reducer, 46 is the first top plate, 47 is the sensor connecting seat, 48 is the transition push plate, 49 is the guide rod, 50 is the guide shaft, 51 is the first ball screw, 52 is the probe rod, 53 is the second fixed pulley, 54 is the second fixed pulley mounting frame, and 55 is the second beam plate. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to specific implementation examples and accompanying drawings: Example 1: like Figure 1-3 As shown, a suction anchor-based centrifuge oblique loading test device and observation system are disclosed. The device includes a test foundation 1 inside a model box, a suction anchor model 2, rigging 13, a pulley support assembly 3, a camera bracket 4, a laser displacement measurement assembly 5, a horizontal loading mechanism 6, a horizontal loading mechanism support frame 7, and a vertical loading mechanism 8. The entire system is placed on the centrifuge basket. Specifically, the suction anchor model 2 is installed in the test foundation 1 by pumping water or static pressure. The model anchor point 12 is connected to the horizontal loading mechanism 6 via the rigging 13 and the pulley support assembly 3. The pulley support assembly 3, camera bracket 4, laser displacement measurement assembly 5, vertical loading mechanism 8, horizontal loading mechanism 6, and horizontal loading mechanism support frame 7 are all bolted to the top or side of the model box.

[0038] The test foundation 1 is the soil used for the suction anchor model 2. In practice, this device is applicable to soils of any type, including sand, silt, or clay. The test foundation 1 can be prepared using general soil mechanics methods, such as using the rain method for sandy soil or the mud method for clay soil. In practice, depending on the experimental requirements, an appropriate height for the test foundation 1 can be reserved inside the model box, typically 0.5 to 0.7 times the height of the model box.

[0039] like Figure 4-6 As shown, the suction anchor model 2 is a cylindrical hollow structure with an opening at the top, and is made entirely of aluminum alloy or Q235B structural steel. The suction anchor model 2 is designed as a detachable structure, including a threaded mounting hole 9, an accelerometer mounting slot 10, a bottom bore gauge bracket 11, a model anchor point 12, and a buckle 14.

[0040] The threaded mounting holes 9 include a water pump valve hole 9a, a pore pressure gauge mounting hole 9b, a pore pressure gauge outlet hole 9c, and a drain hole 9d. The water pump valve hole 9a is used for installing an external water pumping device on the suction anchor model 2. The pore pressure gauge mounting hole 9b is used for installing a top pore pressure gauge. The pore pressure gauge outlet hole 9c is used for the pore pressure gauge outlet. The drain hole 9d is used for drainage during installation and is sealed after completion. The accelerometer mounting slot 10 is located at the top center of the suction anchor model 2 and has threaded holes around it for installing and fixing accelerometers to measure the motion response of the suction anchor model during loading. The bottom pore pressure gauge bracket 11 is located on the bottom side wall of the suction anchor model 2 and is connected to the outer wall of the suction anchor model 2 by screws. It is used to install the pore pressure gauge on the inner bottom of the suction anchor model 2 to measure the pore pressure inside the suction anchor model. After all sensors are installed, the other end is connected to an aerial plug and then connected to the data acquisition system.

[0041] Model anchor point 12 is the loading point of the suction anchor model 2, located on the outer wall of the suction anchor model 2, and is a circular hanging lug. Model anchor point 12 is connected to one end of the rigging 13 via buckle 14. The height of model anchor point 12 can be adjusted arbitrarily according to experimental needs, usually at 0.5~0.7 times the height of the suction anchor model 2 from the top.

[0042] like Figure 7-9As shown, the pulley support assembly 3 includes a first fixed pulley 15, a second fixed pulley 53, a fixed pulley block 16, a first fixed pulley mounting frame 17, a second fixed pulley mounting frame 54, a slide column 18, a third base plate 19, a third top plate 20, a first beam plate 21, a second beam plate 55, and a movable frame 22, all made of Q235B steel. The rigging 13 extends from the model anchor point 12, is wound twice around the second fixed pulley 53 and the first fixed pulley 15, and then exits. Based on the working principle of the fixed pulley, it can be used to change the direction of the loading force twice; if only one change is needed, one fixed pulley can be removed. Setting up two sets of fixed pulleys, one above the other, also increases the vertical force transmission process, saving space in the model box caused by the oblique pulling of the suction anchor model.

[0043] The third base plate 19 is symmetrically fixed to the top of the model box. The four corners of the third top plate 20 are fixed with slide rail columns 18, which are then fixed to the third base plate 19. The two ends of the first beam plate 21 are connected to the slide rail columns 18 on both sides. Movable frames 22 are movably connected to the slide rails of the slide rail columns 18. The two ends of the second beam plate 55 are connected to the movable frames 22 on both sides. The first fixed pulley mounting frame 17 is fixed to the first beam plate 21, and the first fixed pulley 15 is mounted on the first fixed pulley. The first fixed pulley 15 is mounted on the first fixed pulley 15, and the second fixed pulley 53 is mounted on the second fixed pulley mounting frame 17. The second fixed pulley 15 is fixed on the second beam plate 55, and the second fixed pulley 53 is mounted on the second fixed pulley mounting frame 54. The fixed pulley block 16 is used to fix the first fixed pulley 15 and the second fixed pulley 53 respectively, and to limit the lateral displacement of the first fixed pulley 15 and the second fixed pulley 53. The pulley bracket assembly as a whole serves as a guide device for the rigging 13 and is used to change the force direction of the rigging 13. The top of the first fixed pulley mounting frame 17 is connected to the third top plate 20 by bolts.

[0044] The length of the slide column 18 can be adjusted according to experimental requirements, thereby adjusting the height of the second fixed pulley 53 from the test foundation 1 inside the model box. The adjustable test foundation height is usually set to 40~60 cm. Especially for clay, this can fully avoid the influence of uncertain or unstable foundation settlement height caused by soil consolidation, and facilitate the adjustment of the loading angle of the suction anchor model 2.

[0045] like Figure 10-12As shown, the camera bracket 4 includes a camera assembly 23, a support rod 24, a vertical plate 25, a suspension beam 26, a fourth base plate 27, and a pad 28, all made of Q235B steel. The vertical plate 25 and the fourth base plate 27 are symmetrically arranged and connected by bolts through the pad 28. The vertical plate 25 has a central slide rail connected to the suspension beam 26 by bolts, allowing adjustment of the camera assembly 23's height to suit different focal lengths, especially fixed-focus lenses. The suspension beam 26 also has a hollowed-out slide rail in the middle, and the camera assembly 23 is connected to it by bolts, allowing adjustment of its lateral position. The support rod 24 supports the suspension beam 26, increasing structural strength. The camera assembly 23 is the camera mounting component; its structure can be adjusted according to the camera model and is used to protect the camera. The camera is connected to a computer in the control room via a network cable through the optical transceiver of a centrifuge.

[0046] like Figure 13-14 As shown, the laser displacement measurement assembly 5 includes a positioning beam 29, a lead screw 30, a displacement sensor connecting sleeve 31, a laser displacement sensor 32, and a displacement sensor connecting plate 33. The laser displacement sensor 32 and the displacement sensor connecting plate 33 are bolted together and secured by the upper displacement sensor connecting sleeve 31. The bottom of the lead screw 30 and the displacement sensor connecting sleeve 31 are fixed with nuts and washers, and the top is connected to the positioning beam 29 with nuts and washers. The positioning beam 29 has a slide rail in the middle, which can adjust the lateral position of the lead screw 30. The length of the slide rail in the middle of the positioning beam 29 can be set according to the test requirements, thereby installing different numbers of lead screws 30.

[0047] like Figure 15 As shown, the horizontal loading mechanism 6 includes a second servo motor 34, a second right-angle reducer 35, a second ball screw 36, a guide rod 37, a second base plate 38, a frame 39, a load sensor 40, a loading head 41, and a slide plate 42. The slide plate 42 is fixed to the model box with bolts. The second base plate 38 is fixed to the slide plate 42 with screws. The slide plate 42, along with the entire device, is hoisted onto the model box. Based on the position of the suction anchor model 2, the position of the horizontal loading mechanism 6 on the slide plate 42 is moved so that the loading head 41 and the suction anchor model 2 are on the same axis. The second servo motor 34 and the second right-angle reducer 35 are connected to an external data acquisition instrument or industrial control computer, driving the second ball screw 36 to rotate, converting the rotational motion into linear motion, and pushing the guide rod 37 to displacement. The end of the guide rod 37 is connected to the load sensor 40 and the loading head 41. The loading head 41 is connected to the anchor chain and tightened with screws. The second servo motor 34 and the second right-angle reducer 35 are connected to an external data acquisition instrument, driving the second ball screw 36 to rotate, converting the rotational motion into linear motion, and pushing the guide rod 37 to move. The loading head at the end of the guide rod 37 can be designed with different connecting accessories according to the experimental model. The load sensor 40 realizes the displacement or force loading simulation required by the experiment through the negative feedback control principle.

[0048] The horizontal loading mechanism 6 support frame includes a screw and a diagonal brace, serving as an auxiliary device for installing the horizontal loading mechanism. If the model box is not long enough, the diagonal brace can be used as an extension mechanism to support the horizontal loading mechanism.

[0049] like Figure 16-18 As shown, the vertical loading mechanism 8 includes a first servo motor 43, a first right-angle reducer 44, a first top plate 45, a sensor connector 46, a transition push plate 47, a first bottom plate 48, a guide rod 49, a guide shaft 50, a first ball screw 51, and a probe 52. The first bottom plate 48 is bolted to the top of the model box. The first servo motor 43 and the first right-angle reducer 44 are fixed to the first top plate 45 by I-beams and are connected to an external data acquisition instrument or industrial control computer. Holes are symmetrically arranged around the first top plate 45, which is connected to the transition push plate 47 and the first bottom plate 48 via the guide rod 49. The first right-angle reducer 44 and the first top plate 45 are connected to the first ball screw 51 and to the transition push plate 47 and the first bottom plate 48, converting the rotational displacement driven by the first servo motor 43 into vertical displacement to move the transition push plate 47. A threaded hole is provided in the center of the transition push plate 47 for connecting the probe 52. The probe rod 52 can be fitted with a suitable probe or connector at its end according to the test requirements. The guide spool 50 is used to fix the signal line of the probe or connector. In specific implementations, for sandy soil foundations, the probe is a CPTu; for clay soil foundations, the probe is a T-bar. In addition, if used for vertical loading tests, a suitable loading head can be used.

[0050] A laser displacement sensor, a pore pressure gauge, and an accelerometer were mounted on the laser displacement measurement component 5 and the suction anchor model 2 to observe the motion response of the suction anchor model and the evolution characteristics of pore pressure at different locations. A camera was arranged on the camera bracket assembly to monitor the experimental status of the model in real time, and the failure modes and failure mechanisms of the suction anchor model were identified by combining PIV technology.

[0051] Example 2: The specific process of conducting a suction anchor oblique loading test on a centrifuge based on the system described in Example 1 is as follows: Step 1: Calibrate the installation position and angle of the suction anchor model 2, and prepare the test foundation 1. For sandy soil foundations, control the sand falling speed according to the calibrated funnel opening and drop distance to obtain a sandy seabed with a set density; for clay soil foundations, lay drainage pipes and sand cushions at the bottom of the model box, and pour mud into the model box after preparation.

[0052] Step 2: After the test foundation 1 is prepared, install the pulley support assembly 3, camera support 4, laser displacement measurement assembly 5, vertical loading mechanism 8, horizontal loading mechanism 6, and horizontal loading mechanism support frame 7 one by one, and fix them to the model box with bolts according to the marked installation positions. For sandy soil foundations, install CPTu probes on vertical loading mechanism 8; for sandy soil foundations, install T-bar probes on vertical loading mechanism 8.

[0053] Step 3: Connect the model anchor point 12 of the suction anchor model 2, where the sensor is installed, to the loading head 41 of the horizontal loading mechanism 6 via the anchor chain through the pulley bracket assembly 3. Adjust the position and height of the pulley bracket assembly 3, and tension the anchor chain to the design value.

[0054] Step 4: Connect all sensor data acquisition, arrange the light source, and connect the camera. Connect the controllers for the vertical loading mechanism 8 and the horizontal loading mechanism 6.

[0055] Step 5: Start the centrifuge. For sandy soil foundations, start the vertical loading mechanism 8 to test the soil strength using CPTu; for clay soil foundations, after the consolidation test foundation 1 has dissipated the pore pressure, start the vertical loading mechanism 8 to test the soil strength using T-bar.

[0056] Step 6: After the soil strength test is completed, activate the horizontal loading mechanism 6 to pull the anchor chain and apply static or cyclic loads to the suction anchor model 2 according to the preset working conditions. Record the sensor data from the centrifuge until the loading is complete.

[0057] As can be seen from this embodiment, the present invention can: 1. Enable suction anchor loading tests for different foundation types and working conditions through a single system. Furthermore, the problem of uncertain soil height after foundation settlement or consolidation can be avoided by adjusting the height of the second fixed pulley. Setting the loading angle is very convenient, and it can simulate various loading conditions. 2. Capture the multi-degree-of-freedom motion response and soil state of the suction anchor model through multiple types of sensors, increasing the observation dimension of the suction anchor from two-dimensional to three-dimensional, thereby effectively analyzing the failure mode and failure mechanism of the suction anchor model.

Claims

1. A centrifuge testing and observation system suitable for suction anchors, wherein the entire system is placed on the centrifuge's basket, characterized in that, The system includes a model box, a suction anchor model, rigging, a vertical loading mechanism, a horizontal loading mechanism, a pulley support assembly, a camera bracket, and a laser displacement measurement assembly. The model box contains a test foundation, within which the suction anchor model is placed. One end of the rigging is connected to the suction anchor model, and the other end is connected to the horizontal loading mechanism. The vertical loading mechanism is used for vertical loading tests of the foundation soil strength. The horizontal loading mechanism is used to apply static and cyclic loads to the suction anchor model. The pulley support assembly is used to change the force direction of the rigging. The camera bracket is used to monitor the loading status of the suction anchor model in real time, and the laser displacement measurement assembly is used to monitor the displacement of the suction anchor model in real time.

2. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The suction anchor model is equipped with a bottom pore pressure gauge bracket, threaded mounting holes, an accelerometer mounting slot, a model anchor point, a bottom pore pressure gauge, a top pore pressure gauge, and an accelerometer. The suction anchor model is a cylindrical hollow structure. The bottom pore pressure gauge bracket is fixed to the bottom inner side of the suction anchor model for mounting the bottom pore pressure gauge. The threaded mounting holes are located at the top of the suction anchor model and include: a water pumping valve hole, a pore pressure gauge mounting hole, a pore pressure gauge outlet hole, and a drainage hole. The water pumping valve hole is used for installing an external water pumping device on the suction anchor model. The pore pressure gauge mounting hole is used for mounting the top pore pressure gauge. The pore pressure gauge outlet hole is used for the pore pressure gauge to exit. The drainage hole is used for drainage during installation and is sealed after completion. The accelerometer mounting slot is located at the top of the suction anchor model for mounting the accelerometer. The accelerometer is used to measure the motion response of the suction anchor model during loading. The model anchor point is the suction anchor loading point, located on the outer wall of the suction anchor model, and is used to connect to the rigging.

3. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The rigging is one or more of anchor chains and wire ropes.

4. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The vertical loading mechanism includes a first servo motor, a first right-angle reducer, a first top plate, a sensor connector, a transition push plate, a first bottom plate, a guide rod, a guide shaft, a first ball screw, and a probe rod. The first base plate is fixed to the model box. The first top plate is fixedly connected to the first base plate via a guide rod. The first servo motor and the first right-angle reducer are fixed to the first top plate. The output end of the first servo motor is connected to the input end of the first right-angle reducer. One end of the first ball screw passes through the first top plate and is connected to the output end of the first right-angle reducer. The transition push plate is located between the first top plate and the first base plate, and is sleeved on the guide rod and threadedly connected to the first ball screw. The rotation of the first ball screw drives the transition push plate to move. The sensor connecting seat is fixed to the transition push plate. One end of the probe rod is connected to the sensor connecting seat, and the other end is equipped with a probe for detecting soil strength. The guide shaft is used to fix the signal line of the probe.

5. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The horizontal loading mechanism includes a second servo motor, a second right-angle reducer, a second ball screw, a guide rod, a second base plate, a frame, a load sensor, a slide plate, and a loading head; The slide plate is fixed to the model box, the second base plate is fixed to the slide plate, the second servo motor and the second right-angle reducer are fixed on the second base plate, the output end of the second servo motor is connected to the input end of the second right-angle reducer, one end of the second ball screw is connected to the output end of the second right-angle reducer, and the other end is movably connected to the frame, one end of the guide rod is sleeved on the second threaded screw, the second threaded screw rotates, pushing the guide rod assembly to move, the load sensor and the loading head are fixed to the other end of the guide rod, and the loading head is fixedly connected to the end of the rigging.

6. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The pulley support assembly includes a first fixed pulley, a second fixed pulley, two fixed pulley blocks, a first fixed pulley mounting frame, a second fixed pulley mounting frame, four slide rail columns, two third base plates, a third top plate, a first beam plate, a second beam plate, and two movable frames; The third base plate is symmetrically fixed to the top of the model box. Slide columns are fixed to the four corners of the third top plate, and the slide columns are fixed to the third base plate. The two ends of the first beam plate are connected to the slide columns on both sides. Movable frames are movably connected to the slide columns. The two ends of the second beam plate are connected to the movable frames on both sides. The first fixed pulley mounting frame is fixed to the first beam plate, and the first fixed pulley is mounted on the first fixed pulley mounting frame. The second fixed pulley mounting frame is fixed to the second beam plate, and the second fixed pulley is mounted on the second fixed pulley mounting frame. Fixed pulley blocks are used to fix the first and second fixed pulleys respectively. The pulley bracket assembly as a whole serves as a guide device for the rigging, used to change the direction of force on the rigging.

7. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The camera support includes a camera, a camera assembly, a support rod, a vertical plate, a hanging beam, and a fourth base plate. The camera is connected to a computer in the control room via a network cable through the optical transceiver of a centrifuge. The computer monitors the loading status of the suction anchor model in real time. The camera assembly is used to mount the camera and is slidably connected to the hanging beam. The hanging beam has a slide rail for the camera assembly to slide. Both ends of the hanging beam are slidably connected to the vertical plate. One end of the support rod is connected to the hanging beam, and the other end is connected to the fourth base plate, which is used to support the hanging beam to adjust to different heights. The fourth base plate is fixed to the top of the model box and is fixedly connected to the vertical plate.

8. The centrifuge testing and observation system for suction anchors according to claim 1, characterized in that, The laser displacement measurement assembly includes a positioning beam, a lead screw, a displacement sensor connecting sleeve, a laser displacement sensor, and a displacement sensor connecting plate. The positioning beam is fixed to the model box and has a slide rail with a central hollow section. One end of the lead screw is fixed to the slide rail, and the displacement sensor is connected to the other end of the lead screw in sequence through the displacement sensor connecting plate and the displacement sensor connecting sleeve.

9. A method for testing and observing a centrifuge system for suction anchors based on any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Determine the installation position and angle of the suction anchor model and prepare the test foundation; Step 2: After the test foundation is prepared, install the pulley support assembly, camera support, laser displacement measurement assembly, vertical loading mechanism, horizontal loading mechanism and horizontal loading mechanism support frame one by one, and fix them to the model box with bolts according to the marked installation position; Step 3: Connect the suction anchor model to the loading head of the horizontal loading mechanism via a rigging system and pulley support assembly; adjust the position and height of the pulley support assembly, and tension the rigging loading angle to the design value; Step 4: Connect the sensors in the system to the centrifuge's data acquisition, arrange the light source, and connect the camera; connect the vertical loading mechanism and the horizontal loading mechanism controller; Step 5: Start the centrifuge. For sandy soil foundations, start the vertical loading mechanism to test the soil strength. Step 6: After the soil strength test is completed, start the horizontal loading mechanism to pull the rigging and apply static or cyclic load to the suction anchor model according to the preset working conditions; record the sensor data according to the centrifuge data until the horizontal loading mechanism shrinks to its minimum.

10. The method for a centrifuge test and observation system for suction anchors according to claim 9, characterized in that, In step 1, for sandy soil foundations, the sand falling speed is controlled according to the preset funnel opening and falling distance to obtain a sandy seabed with a set density; for clay soil foundations, drainage pipes and sand cushion layers are laid at the bottom of the model box, and mud is prepared and poured into the model box. In step 2, for sandy soil foundations, a CPTu probe is installed in the vertical loading mechanism; for clay soil foundations, a T-bar probe is installed in the vertical loading mechanism. In step 5, the soil strength is tested: for sandy soil foundations, the vertical loading mechanism is activated to test the soil strength using CPTu; for clay soil foundations, after the pore pressure dissipates from the consolidation test foundation, the vertical loading mechanism is activated to test the soil strength using T-bar.

Images