Submarine sediment three-dimensional mechanical parameter in-situ test device and working method thereof

Abstract

The invention discloses a submarine sediment three-dimensional mechanical parameter in-situ test device and a working method thereof, and belongs to the technical field of ocean engineering geological survey. The device comprises a penetration main rod module, a movable probe rod module, a replaceable probe module, a multi-dimensional sensing module and a control and data acquisition module. The device realizes a vertical penetration test through the penetration main rod, performs a horizontal loading and rotary disturbance test by using the movable probe rod, supports different-depth layered cycle tests, and integrates various sensors for pore water pressure and the like. The working method comprises the steps of device calibration, vertical penetration testing, target depth horizontal loading, rotation disturbance effect testing and layered cycle testing, and multi-dimensional mechanical parameters such as undrained shear strength, a p-y curve and pore water pressure can be synchronously obtained. According to the invention, multifunctional integrated in-situ testing is realized, data consistency and operation efficiency are improved, and comprehensive and efficient technical support is provided for oceanographic engineering geological survey and basic design.

Description

Technical Field

[0001] This invention relates to the field of marine engineering geological exploration technology, and more specifically, to an in-situ testing device for three-dimensional mechanical parameters of seabed sediments and its working method. Background Technology

[0002] Currently, in the construction of offshore wind power foundations, offshore oil and gas development, deep-sea mining, and various marine engineering projects, the load-bearing capacity, deformation, and stability of seabed sediments directly affect the safety and service performance of engineering structures such as pile foundations, anchorages, and pipeline laying. Therefore, the engineering survey stage typically requires the acquisition and evaluation of multiple mechanical properties of seabed sediments to support parameter inversion, design calculations, and construction control.

[0003] Among existing in-situ testing methods for marine sediments, the static cone penetration test (CPT) technique is widely used. It is typically used to measure indicators such as cone tip resistance, sidewall friction, and pore water pressure during the penetration process, thereby estimating sediment strength and state parameters. Meanwhile, devices with horizontal loading / displacement capabilities (such as modules for obtaining py curves) have emerged in recent years, enabling the characterization of lateral reaction forces in soil by applying horizontal displacement or loads, providing a basis for the design of offshore pile foundations.

[0004] In the field of marine soil mechanics testing, specialized devices for soft soil characteristics have also been proposed. For example, Chinese Patent CN 110824147 B (application number 201911297379.6, Dalian University of Technology) discloses a "fully fluid spherical penetration device and method for laboratory and shipboard testing," which uses a spherical probe to penetrate and integrate sensors such as pressure and pore water pressure. This allows for in-situ and shipboard testing of parameters such as undrained shear strength and pore water pressure in seabed soft soil. This type of technology improves the accuracy and applicability of testing weak sediments to a certain extent, and is particularly suitable for obtaining parameters of low-strength, high-water-content, and highly sensitive marine soft soils.

[0005] However, existing in-situ testing equipment still has certain limitations: First, the testing dimensions are often too singular, usually focusing on vertical penetration response or single-direction loading response, making it difficult to take into account multiple working conditions such as vertical, horizontal and disturbance effects within the same system; Second, when testing different parameters or different directions, it is often necessary to change the device, repeat the deployment or resampling, resulting in low operation efficiency and high cost, and may introduce spatial differences between different test points; Third, the ability to characterize the spatial continuity of sediments at different depths is insufficient, making it difficult to achieve simultaneous acquisition of multi-dimensional responses that change with depth on a single device, thus limiting the three-dimensional in-situ understanding and refined parameter modeling of the "vertical-horizontal-disturbance" coupled behavior of sediments.

[0006] Therefore, it is necessary to provide a technical solution that enables multi-dimensional in-situ testing of seabed sediments to improve testing efficiency and data consistency, and enhance the comprehensive characterization of the mechanical responses of sediments at different depths and in multiple directions. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides an in-situ experimental device for three-dimensional mechanical parameters of seabed sediments and its working method.

[0008] This invention is achieved through the following technical solution: an in-situ experimental device for three-dimensional mechanical parameters of seabed sediments, comprising: The penetrating main rod module includes a penetrating main rod and a rotating shaft, coupling, and geared motor placed inside the penetrating main rod. The penetrating main rod is a rigid hollow rod. A rotating shaft is installed inside the penetrating main rod, which is arranged along the axial direction of the penetrating main rod and can rotate relative to the penetrating main rod. The top end of the rotating shaft is connected to the output shaft of the geared motor through a coupling. A torque sensor is installed on the rotating shaft. An inclinometer is installed on the upper inner wall of the penetrating main rod. The rotating shaft and the inner wall of the penetrating main rod are mutually supported and connected by several support frames. The support frame includes a bearing. The inner ring of the bearing is fixedly fitted on the rotating shaft. One end of a support rod is fixedly connected to the outer wall of the outer ring of the bearing at equal intervals. The other end of the support rod is fixedly connected to the inner wall of the penetrating main rod. A movable probe module is located in the middle of the main rod. A cavity is opened in the middle of the main rod to accommodate the movable probe module. The movable probe module includes an electric telescopic rod, a first high-precision micro pressure sensor, a rigid cylindrical test section, two connecting rods, and a rotating filling section. The end of the electric telescopic rod is fixed on the rotating shaft. The end of the first high-precision micro pressure sensor is installed at the output end of the electric telescopic rod. The rigid cylindrical test section is fixedly installed at the front end of the first high-precision micro pressure sensor. The rotating filling section is a rigid hollow cylinder with an opening on one side to accommodate the electric telescopic rod, the first high-precision micro pressure sensor, and the rigid cylindrical test section. The inner wall of the rotating filling section is connected to the rotating shaft through two connecting rods. The replaceable probe module includes a replaceable probe, which is connected to the lower end of a rigid short rod at the bottom of the main rod via a quick-connect interface. The upper end of the rigid short rod is connected to a second high-precision micro pressure sensor. The two sides of the second high-precision micro pressure sensor are fixed to the inner wall of the main rod via fixing rods. The outer wall of the replaceable probe is in direct contact with the soil. It integrates a pore water pressure sensor inside. The nose of the replaceable probe is provided with a water inlet. The multi-dimensional sensing module includes an inclinometer, a torque sensor, a first high-precision miniature pressure sensor, a second high-precision miniature pressure sensor, and a pore water pressure sensor. The control and data acquisition module includes a data acquisition unit and a control driver; the data acquisition unit is communicatively connected to all sensors in the multi-dimensional sensing module, the data acquisition unit is communicatively connected to the control driver, and the control driver is communicatively connected to the electric telescopic rod and the geared motor.

[0009] As a preferred option, the material of the penetrating main rod is titanium alloy or duplex stainless steel, and the outer surface is coated with an anodized / ceramic coating + PTFE anti-fouling layer; the sliding surface is coated with DLC or MoS2 solid lubricant coating.

[0010] As a preferred option, the probe can be replaced with one of the following: a ball-shaped, cone-shaped, or T-shaped probe.

[0011] As a preferred option, a thrust washer is provided between the rotating filling section and the penetrating main rod.

[0012] Furthermore, the thrust washer is made of bronze-graphite composite material or PTFE composite material.

[0013] A method for operating a three-dimensional mechanical parameter in-situ testing device for seabed sediments includes the following steps: S1. Equipment preparation and calibration: Select and install replaceable probes according to the type of soil layer to be tested; calibrate the inclinometer, torque sensor, first high-precision miniature pressure sensor, second high-precision miniature pressure sensor and pore water pressure sensor; set up the equipment at the test point. S2. Vertical Penetration and Profile Test: Control the penetrating platform and penetrating main rod to press the device into the seabed sediment at a pre-set constant rate; during this process, the data acquisition instrument synchronously and continuously collects the penetration resistance measured by the second high-precision micro pressure sensor, the pore water pressure measured by the pore water pressure sensor, and the data from the inclinometer to obtain the undrained shear strength and pore water pressure profile. S3. Target Depth Horizontal Loading Test: After penetrating to the first target depth, stop vertical movement; start the electric telescopic rod to extend the rigid cylindrical test section horizontally to make it contact and squeeze the soil; then perform multi-stage displacement control loading, and simultaneously collect the horizontal resistance of the rigid cylindrical test section to obtain the py curve, undrained shear strength and pore pressure evolution data of the soil at this depth. S4. Rotational Disturbance Effect Test: After completing the horizontal loading test, keep the rigid cylindrical test section in a horizontal position, start the reduction motor, and drive it to rotate around its own axis according to the pre-set speed and number of revolutions; during the rotation and the holding phase after rotation, continuously collect data from the torque sensor and pore water pressure sensor to obtain the pore water pressure response of the soil before and after disturbance, as well as the undrained shear strength (one revolution), disturbance strength (multiple revolutions), and sensitivity (ratio of the two). S5. Layered Cyclic Test: Drive the main penetrator to continue penetrating downwards to the next target depth, repeating steps S3 and S4; to achieve layered, three-dimensional in-situ mechanical parameter testing of seabed sediments along the depth direction.

[0014] By employing the above technical solutions, this invention has the following beneficial effects compared to existing technologies: 1. It has a replaceable probe function, which allows the device to replace probes of different shapes (spherical, T-shaped, conical, etc.) according to the soil type to adapt to a variety of seabed sediments from ultra-soft soil to dense sand, thereby reliably testing their vertical penetration resistance and pore water pressure, and broadening the testing application range of the device.

[0015] 2. It has a horizontal movement function. After vertically penetrating to the target depth, the middle probe can be moved horizontally in a controllable manner. It can directly and in situ measure the py curve and the corresponding pore water pressure evolution process used for pile foundation design, realize the direct acquisition of the resistance characteristics of horizontal soil, and reduce the uncertainty of traditional indirect derivation methods.

[0016] 3. It features a rotational cyclic function. After the horizontal movement test is completed, the central probe can rotate along the original axis (including one or more cycles), thereby obtaining the changes in the horizontal penetration resistance and pore water pressure response of the soil under cyclic shear disturbance. This function provides a unique in-situ testing method for quantitatively studying the structural effects, thixotropy, and performance degradation of sediments under cyclic loading.

[0017] 4. It has a layered cyclic testing function. After completing the above functions, the device can drive the main penetrator to continue penetrating downwards, repeating the entire test process of "vertical testing - horizontal loading - rotational disturbance" at the new depth. This method can systematically form three-dimensional in-situ mechanical parameter profiles of sediments at different depths, realizing continuous and precise exploration from "point" to "volume", making the device essentially a mobile "seabed laboratory".

[0018] In summary, this invention integrates four major functions—replaceable probe, horizontal movement, rotational circulation, and stratified cyclic testing—into a single device, achieving multifunctional integration and replacing various traditional equipment, significantly improving on-site testing efficiency. It can directly acquire vertical and horizontal strength, stiffness, and pore water pressure variation curves, providing comprehensive and direct data. In particular, its rotational circulation function can study sediment structure effects through cyclic perturbation testing. Finally, its stratified testing mode supports stratified, three-dimensional continuous in-situ testing, providing an unprecedented comprehensive, in-situ, and efficient solution for marine engineering geological exploration and basic design.

[0019] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the in-situ experimental device for three-dimensional mechanical parameters of seabed sediments according to the present invention; Figure 2 A three-dimensional structural diagram of the main rod module; Figure 3 A schematic diagram of the three-dimensional structure after removing the main shaft from the main shaft module; Figure 4 A schematic diagram of the cross-sectional structure of the main rod module; Figure 5 A schematic diagram of the cross-sectional structure penetrating the lower part of the main rod module. Figure 6 This is a three-dimensional structural diagram of the movable probe module; Figure 7 This is a three-dimensional structural diagram of the interior of the movable probe module; Figure 8 This is a schematic diagram of the three-dimensional structure of the support frame; Figure 9 This is a three-dimensional structural diagram of the movable probe module when it is horizontally extended. Figure 10 This is a flowchart illustrating the working method of the present invention. in, Figures 1 to 10 The correspondence between the reference numerals and components in the attached drawings is as follows: 1. Penetrating main rod, 2. Rotating shaft, 3. Torque sensor, 4. Inclinometer, 5. Support frame, 5-1 bearing, 5-2 support rod, 6. Electric telescopic rod, 7. First high-precision miniature pressure sensor, 8. Rigid cylindrical test section, 9. Connecting rod, 10. Rotary filling section, 11. Replaceable probe, 12. Quick-change interface, 13. Rigid short rod, 14. Second high-precision miniature pressure sensor, 15. Pore water pressure sensor, 16. Inlet, 18. Data acquisition instrument, 19. Control driver, 20. Thrust washer, 21. Coupling, 22. Gear motor, 23. Fixed rod. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0023] The following is combined Figures 1 to 10 The in-situ experimental apparatus for three-dimensional mechanical parameters of seabed sediments and its working method according to embodiments of the present invention are described in detail.

[0024] like Figure 1 As shown, the present invention proposes a technical solution to achieve the present invention through the following: an in-situ experimental device for three-dimensional mechanical parameters of seabed sediments, comprising: The penetrating main rod module includes a penetrating main rod 1 and a rotating shaft 2, a coupling 21, and a geared motor 22 placed inside the penetrating main rod 1. The penetrating main rod 1 is a rigid hollow rod, and the material of the penetrating main rod 1 is titanium alloy or duplex stainless steel. The outer surface is coated with an anodized / ceramic coating + PTFE anti-fouling layer; the sliding surface is coated with DLC or MoS2 solid lubricant coating. A rotating shaft 2 is installed inside the main rod 1. The rotating shaft 2 is arranged along the axial direction of the main rod and can rotate relative to the main rod 1. The top end of the rotating shaft 2 is connected to the output shaft of the geared motor 22 through a coupling 21. A torque sensor 3 is installed on the rotating shaft 2 to obtain torque information during the engineering process. An inclinometer 4 is installed on the upper inner wall of the main rod 1. The rotating shaft 2 and the inner wall of the main rod 1 are supported and connected to each other by several support frames 5. The support frame 5 includes a bearing 5-1. The inner ring of the bearing 5-1 is fixedly fitted on the rotating shaft 2. One end of the support rod 5-2 is fixedly connected at equal intervals to the outer wall of the outer ring of the bearing 5-1. The other end of the support rod 5-2 is fixedly connected to the inner wall of the main rod 1. A movable probe module is located in the middle of the main rod 1. A cavity is formed in the middle of the main rod 1 to accommodate the movable probe module. The movable probe module includes an electric telescopic rod 6, a first high-precision miniature pressure sensor 7, a rigid cylindrical test section 8, two connecting rods 9, and a rotating filling section 10. The end of the electric telescopic rod 6 is fixed to a rotating shaft 2. The end of the first high-precision miniature pressure sensor 7 is installed at the output end of the electric telescopic rod 6. The rigid cylindrical test section 8 is fixedly installed at the front end of the first high-precision miniature pressure sensor 7. The rotating filling section 10 has a cavity on one side to accommodate the electric telescopic rod 6, the first high-precision miniature pressure sensor 7, a rigid cylindrical test section 8, two connecting rods 9, and a rotating filling section 10. The high-precision miniature pressure sensor 7 and the rigid cylindrical test section 8 are open, rigid hollow cylinders. The inner wall of the rotating filling section 10 is connected to the rotating shaft 2 through two connecting rods 9. Driven by the electric telescopic rod 6, the rigid cylindrical test section 8 extends or retracts horizontally in a direction perpendicular to the axis of the penetrating main rod 1. The rigid cylindrical test section 8 and the rotating filling section 10 can be driven by the rotating shaft 2 to rotate continuously around their own axis. A thrust washer 20 is provided between the rotating filling section 10 and the penetrating main rod 1. The thrust washer 20 is made of bronze-graphite composite material or PTFE composite material.

[0025] The replaceable probe module includes a replaceable probe 11, which is connected to the lower end of a rigid short rod 13 at the bottom of the main penetration rod 1 via a quick-change interface 12. The upper end of the rigid short rod 13 is connected to a second high-precision miniature pressure sensor 14. The two sides of the second high-precision miniature pressure sensor 14 are fixed to the inner wall of the main penetration rod 1 via fixing rods 23, achieving a working state of side-fixed cantilever at both ends. The rigid short rod is not in contact with the main penetration rod and is used to apply the penetration resistance experienced by the replaceable probe to the second high-precision miniature pressure sensor. The outer wall of the replaceable probe 11 is in direct contact with the soil, and a pore water pressure sensor 15 is integrated inside it. A water inlet 16 is opened at the nose of the replaceable probe 11, and the pore water pressure sensor tests the pore water pressure of the sample during the penetration process through the water inlet. The multi-dimensional sensing module includes an inclinometer 4, a torque sensor 3, a first high-precision miniature pressure sensor 7, a second high-precision miniature pressure sensor 14, and a pore water pressure sensor 15. The control and data acquisition module includes a data acquisition unit 18 and a control driver 19. The data acquisition unit 18 is communicatively connected to all sensors in the multi-dimensional sensing module, the data acquisition unit 18 is communicatively connected to the control driver 19, the control driver 19 is communicatively connected to the electric telescopic rod 6 and the geared motor 22, and the control driver 19 is also connected to the penetration platform.

[0026] A method for operating a three-dimensional mechanical parameter in-situ testing device for seabed sediments includes the following steps: S1. Device preparation and calibration: Select and install the replaceable probe 11 according to the type of soil layer to be tested; calibrate the inclinometer 4, torque sensor 3, first high-precision miniature pressure sensor 7, second high-precision miniature pressure sensor 14 and pore water pressure sensor 15; set up the device at the test point. S2. Vertical Penetration and Profile Test: Control the penetrating platform and penetrating main rod 1 to press the device into the seabed sediment at a pre-set constant rate; during this process, the data acquisition instrument synchronously and continuously collects the penetration resistance measured by the second high-precision micro pressure sensor 14, the pore water pressure measured by the pore water pressure sensor 15, and the data of the inclinometer 4 to obtain the undrained shear strength and pore water pressure profile. S3. Target Depth Horizontal Loading Test: After penetrating to the first target depth, stop the vertical movement; start the electric telescopic rod 6 to extend the rigid cylindrical test section 8 horizontally as a whole, so that it contacts and squeezes the soil; then perform multi-stage displacement control loading, and simultaneously collect the horizontal resistance of the rigid cylindrical test section 8 to obtain the py curve, undrained shear strength and pore pressure evolution data of the soil at this depth. S4. Rotational Disturbance Effect Test: After completing the horizontal loading test, keep the rigid cylindrical test section 8 in a horizontal position, start the reduction motor 22, and drive it to rotate around its own axis according to the pre-set speed and number of revolutions; during the rotation and the holding phase after rotation, continuously collect data from the torque sensor and pore water pressure sensor to obtain the pore water pressure response of the soil before and after disturbance, as well as the undrained shear strength (one revolution), disturbance strength (multiple revolutions), and sensitivity (ratio of the two). S5. Layered Cyclic Test: Drive the main penetrator to continue penetrating downwards to the next target depth, repeating steps S3 and S4; to achieve layered, three-dimensional in-situ mechanical parameter testing of seabed sediments along the depth direction.

[0027] In the description of this invention, the term "a plurality of" refers to two or more. Unless otherwise explicitly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0028] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An in-situ experimental device for three-dimensional mechanical parameters of seabed sediments, characterized in that... ,include: The main rod module includes a main rod (1) and a rotating shaft (2), a coupling (21), and a geared motor (22) placed inside the main rod (1). The main rod (1) is a rigid hollow rod. The rotating shaft (2) is installed inside the main rod (1). The rotating shaft (2) is arranged along the axial direction of the main rod and can rotate relative to the main rod (1). The top end of the rotating shaft (2) is connected to the output shaft of the geared motor (22) through the coupling (21). A torque sensor (3) is installed on the rotating shaft (2). An inclinometer (4) is installed on the upper inner wall of the main rod (1). The rotating shaft (2) and the inner wall of the main rod (1) are supported and connected to each other by several support frames (5). The support frame (5) includes a bearing (5-1). The inner ring of the bearing (5-1) is fixedly fitted on the rotating shaft (2). One end of the support rod (5-2) is fixedly connected at equal intervals on the outer wall of the outer ring of the bearing (5-1). The other end of the support rod (5-2) is fixedly connected to the inner wall of the main rod (1). The movable probe module is located in the middle of the main rod (1). The middle of the main rod (1) has a cavity to accommodate the movable probe module. The movable probe module includes an electric telescopic rod (6), a first high-precision micro pressure sensor (7), a rigid cylindrical test section (8), two connecting rods (9), and a rotating filling section (10). The end of the electric telescopic rod (6) is fixed on the rotating shaft (2). The end of the first high-precision micro pressure sensor (7) is installed at the output end of the electric telescopic rod (6). The rigid cylindrical test section (8) is fixedly installed at the front end of the first high-precision micro pressure sensor (7). The rotating filling section (10) is a rigid hollow cylinder with an opening on one side to accommodate the electric telescopic rod (6), the first high-precision micro pressure sensor (7), and the rigid cylindrical test section (8). The inner wall of the rotating filling section (10) is connected to the rotating shaft (2) through two connecting rods (9). The replaceable probe module includes a replaceable probe (11). The replaceable probe (11) is connected to the lower end of the rigid short rod (13) at the bottom of the main rod (1) via a quick-change interface (12). The upper end of the rigid short rod (13) is connected to a second high-precision micro pressure sensor (14). The two sides of the second high-precision micro pressure sensor (14) are fixed to the inner wall of the main rod (1) via a fixing rod (23). The outer wall of the replaceable probe (11) is in direct contact with the soil. A pore water pressure sensor (15) is integrated inside the replaceable probe (11). A water inlet (16) is opened at the nose of the replaceable probe (11). The multidimensional sensing module includes an inclinometer (4), a torque sensor (3), a first high-precision miniature pressure sensor (7), a second high-precision miniature pressure sensor (14), and a pore water pressure sensor (15). The control and data acquisition module includes a data acquisition unit (18) and a control driver (19); the data acquisition unit (18) is connected to all sensors in the multidimensional sensing module, the data acquisition unit (18) is connected to the control driver (19), and the control driver (19) is connected to the electric telescopic rod (6) and the geared motor (22).

2. The in-situ experimental apparatus for three-dimensional mechanical parameters of seabed sediments according to claim 1, characterized in that, The material of the penetrating main rod (1) is titanium alloy or duplex stainless steel, and the outer surface is coated with an anodized / ceramic coating + PTFE anti-fouling layer; the sliding surface is coated with DLC or MoS2 solid lubricating coating.

3. The in-situ experimental apparatus for three-dimensional mechanical parameters of seabed sediments according to claim 1, characterized in that, The replaceable probe (11) is one of a spherical, conical, or T-shaped probe.

4. The in-situ experimental apparatus for three-dimensional mechanical parameters of seabed sediments according to claim 1, characterized in that, A thrust washer (20) is provided between the rotating filling section (10) and the penetrating main rod (1).

5. The in-situ experimental apparatus for three-dimensional mechanical parameters of seabed sediments according to claim 4, characterized in that, The thrust washer (20) is made of bronze-graphite composite material or PTFE composite material.

6. A method for operating the in-situ testing apparatus for three-dimensional mechanical parameters of seabed sediments as described in any one of claims 1-5, characterized in that, Specifically, the following steps are included: S1. Device preparation and calibration: Select and install replaceable probes (11) according to the type of soil layer to be tested; calibrate the inclinometer (4), torque sensor (3), first high-precision micro pressure sensor (7), second high-precision micro pressure sensor (14) and pore water pressure sensor (15); set up the device at the test point. S2, Vertical Penetration and Profile Test: Control the penetrating platform and the main penetrating rod (1) to press the device into the seabed sediment at a pre-set constant rate; during this process, the data acquisition instrument synchronously and continuously collects the penetration resistance measured by the second high-precision micro pressure sensor (14), the pore water pressure measured by the pore water pressure sensor (15), and the data of the inclinometer (4) to obtain the undrained shear strength and pore water pressure profile; S3, Target Depth Horizontal Loading Test: After penetrating to the first target depth, stop vertical movement; start the electric telescopic rod (6) to extend the rigid cylindrical test section (8) horizontally as a whole, so that it contacts and squeezes the soil; then carry out multi-level displacement control loading, and simultaneously collect the horizontal resistance of the rigid cylindrical test section (8) to obtain the py curve, undrained shear strength and pore pressure evolution data of the soil at the depth; S4. Rotational disturbance effect test: After completing the horizontal loading test, keep the rigid cylindrical test section (8) in a horizontal position, start the deceleration motor (22), and drive it to rotate around its own axis according to the pre-set speed and number of revolutions; during the rotation and the holding stage after rotation, continuously collect data from the torque sensor and pore water pressure sensor to obtain the pore water pressure response of the soil before and after disturbance, as well as the undrained shear strength, disturbance strength and sensitivity. S5. Layered Cyclic Test: Drive the main penetrator to continue penetrating downwards to the next target depth, repeating steps S3 and S4; to achieve layered, three-dimensional in-situ mechanical parameter testing of seabed sediments along the depth direction.

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