A method and apparatus for sampling a borehole in a soft subsea formation

Abstract

The present application belongs to the technical field of seabed geological exploration, and discloses a hole collapse prevention multilayer sampling device and method for soft seabed geology, which comprises: a submarine sampling platform, comprising a machine body part, a traveling mechanism part fixed below the machine body part, a grabbing mechanism part connected above the machine body part, and a soil storage and transfer part for walking positioning on the seabed; and a submarine sampling device, comprising a soil sampling pile part, which is lowered to a predetermined station through a mother ship steel cable and used for the penetration of the soil sampling pile part and the successive sampling of the soil storage part. The present application is used in combination with a mother ship, is locally positioned on the sea through the mother ship, is sunk into the seabed to perform sampling, can realize small-range multilayer soil sampling, can be used in combination with multiple ships, does not need a separate ship body, has low cost, realizes multiple multilayer successive sampling in the same area, and effectively restores the real stratification state of sediments.

Description

Technical Field

[0001] This invention relates to the technical field of seabed geological exploration, and in particular to a multi-layer sampling device and method for preventing collapse of soft seabed geology, applicable to sampling of soft seabed geology in some marine areas. Background Technology

[0002] Seafloor sediments serve as a natural archive of Earth's history, preserving complete stratigraphic sequences, fossils, and chemical signals. They reveal millions of years of paleoclimate evolution, paleoenvironmental changes, and major geological events, while the mineral resource information they contain is strategically significant for resource exploration. Therefore, achieving high-quality, low-disturbance sampling of seafloor sediments has always been a crucial research direction in the field of marine geological exploration.

[0003] Traditional seabed drilling and sampling equipment often uses rotary cutting devices to drill into the seabed soil layer. However, this method is not suitable for some soft seabed sediments because the rotary cutting equipment tends to disturb the sediments during operation, making it impossible to collect true, original samples, which is detrimental to sample analysis. To address this problem, several improved solutions have been developed in the existing technology.

[0004] Currently, publicly available seabed sampling devices can be mainly divided into two categories. One type focuses on preventing borehole collapse and ensuring drilling stability. It uses a casing to support the borehole wall and employs appropriate straightening or vibration damping mechanisms to reduce drill rod sway, thus preventing borehole collapse during sampling. This type of device addresses borehole collapse issues to some extent under soft geological conditions. However, its casing and sampling tube are usually an integrated, linked structure. The sampling tube completes drilling and sampling inside the casing and then exits with it, allowing only a single sampling operation per deployment, which cannot meet the need for multi-layer, sequential sampling at the same site. The other type focuses on stratified sample collection and fidelity. It uses a sampling tube inserted into the sediment to extract samples from different layers or utilizes negative pressure principles. This type of device has made valuable explorations in the stratified acquisition of pore water or sediments, but most still operate on a single deployment and single sampling model. Furthermore, when applied to loose sandy sediments, the negative pressure extraction method is prone to a sorting effect, preferentially attracting fine particles and affecting the representativeness of the samples. In addition, the existing devices generally adopt a single-function architecture and lack a design concept that organically integrates the three functions of anti-collapse hole support, independent replacement and multiple sampling of sampling containers, and small-scale underwater walking and positioning.

[0005] Seafloor sediments are typically formed through layered accumulation over time, and the internal composition of different layers can vary significantly, including mineral composition, organic matter types, microfossils, and biological communities. Therefore, when exploring seafloor sediments, it is best to take multiple, layer-by-layer samples to reconstruct the true depositional process. However, current technologies often fall short of expectations when applied to these needs. They are limited by the geological characteristics of soft sediments, leading to potential borehole collapse during sampling, and making it difficult to conduct multiple independent layer-by-layer sampling operations in the same area.

[0006] Furthermore, existing seabed sampling devices mostly adopt a single-function architecture, focusing either on drilling sampling or pore water collection, lacking a design concept that organically integrates the three functions of "anti-collapse hole support," "replaceable sampling container," and "seabed small-scale walking and positioning." When it is necessary to complete stratified sampling at multiple depths within the same small area on the seabed, operators often need to deploy and retrieve the sampling device multiple times, resulting in low operational efficiency, high costs, and positioning deviations during each deployment affecting the spatial correspondence between samples at different depths. Summary of the Invention

[0007] Based on the shortcomings of the existing technology, the technical problem to be solved by the present invention is to provide a multi-layer sampling device and method for soft seabed geology with anti-collapse holes. It can be used in conjunction with a mother ship at sea. After the mother ship is partially positioned at sea, the device is sunk and placed on the seabed for sampling. It can achieve multi-layer soil sampling in a small area, and can be used in conjunction with multiple ships without the need for a separate ship hull, and the cost is low.

[0008] To achieve the above objectives, the present invention employs the following technical measures: The multi-layer sampling device for preventing collapse in soft seabed geology of the present invention comprises: a subsea sampling platform, including a body, a traveling mechanism fixed below the body, and a gripping mechanism connected above the body, used for seabed positioning and for storing and transporting the soil sample bin; a subsea sampling device, including a soil sample pile, lowered to a predetermined station via a mother ship's steel cable, used for the penetration of the soil sample pile and the sequential sampling of the soil sample bin; the soil sample pile has a hollow cylindrical structure with a cutting edge at its lower end; a stabilizing mechanism is provided on the outside of the soil sample pile, the stabilizing mechanism including multiple stabilizing supports evenly distributed along the circumference of the pile, one end of each stabilizing support being hinged to a sliding block sliding on a linear guide rail provided on the outer wall of the pile, and the other end being a free end; the upper part of the soil sample pile is provided with... The independent vacuum chamber is equipped with an eccentric vibration mechanism to generate high-frequency, low-amplitude vibrations in the entire soil sampling pile, causing the cutting edge at the lower end of the pile to gradually cut into the seabed sediment, allowing the pile to be smoothly inserted into the ground. The soil sampling pile itself is equipped with a pressing mechanism, which includes a motor fixedly mounted on an upper support inside the pile, a gear connected to the motor's output shaft, and a rack meshing with the gear. The rack extends vertically, and its lower end is fixedly connected to an electromagnet. The soil sampling chamber includes a chamber body for containing collected sediment samples, an electromagnet fixed to the upper end of the chamber body, a closing mechanism located at the lower end of the chamber body, and a cleaning mechanism located outside the chamber body to scrape and remove loose soil adhering to the inner wall of the pile. When energized, the electromagnet generates magnetic force and attracts the opposite magnetic poles of the electromagnet at the lower part of the pressing mechanism.

[0009] Preferably, the closing mechanism includes a hinge and closing plates. The closing plates are multi-triangular structures, and multiple closing plates are connected to the lower periphery of the inner wall of the chamber via hinges. When soil is collected, the closing mechanism is in the open state, and the closing plates are vertically attached to the inner wall of the chamber under the action of gravity or elastic elements, without obstructing the entry of sediment. After soil collection is completed, the closing plates are rotated to a horizontal state by the torsion spring built into the hinge or by electromagnetic drive. Multiple closing plates are joined together to form a closed circular bottom surface, sealing the bottom of the chamber and preventing the sample from falling off during the transfer process.

[0010] Furthermore, the cleaning mechanism includes support rods and elastic cloth. The support rods are multiple elastic rods hinged circumferentially along the outer wall of the silo. The free end of the support rod is connected to an annular elastic cloth, which is fitted onto the outer wall of the silo and can slide up and down along the outer wall. When the soil sampling silo is removed from the soil sampling pile, the support rod opens outward under its own elasticity, causing the elastic cloth to expand outward and adhere to the inner wall of the pile. As the soil sampling silo is lifted, the elastic cloth slides tightly against the inner wall of the pile, scraping off and carrying away the loose soil attached to the inner wall of the pile. A soil discharge port is provided in the middle and lower part of the pile. Excess loose soil carried out by the elastic cloth can be discharged from the outside of the pile through the soil discharge port, thereby maintaining the cleanliness of the internal environment of the pile and reducing the contamination and interference of residual loose soil on the next sampling sample.

[0011] Preferably, the upper side wall of the soil sampling pile is provided with a replacement opening and closing chamber, which is located below the independent vacuum chamber and at the window opened on the side wall of the pile body. The replacement opening and closing chamber includes an opening and closing chamber, a movable door, and a guide rail. The opening and closing chamber is integrated with the side wall of the pile body, forming an internal receiving space. This receiving space is connected to or isolated from the hollow area inside the pile body through the opening and closing of the movable door. The guide rail is fixed horizontally on the upper and lower sides of the opening and closing chamber. The movable door is embedded in the guide rail and is driven by a micro motor to slide horizontally on the guide rail, thereby realizing the opening and closing of the opening and closing chamber window. When it is necessary to put in or take out the soil sampling chamber, the movable door is opened. When soil sampling is performed, the movable door is closed to prevent external sediments or seawater from entering the pile body and interfering with sampling.

[0012] Furthermore, the stabilizing support is connected to the pile body via a spring. The spring is sleeved on the outside of the linear guide rail, with one end abutting against the stabilizing support and the other end abutting against the limiting protrusion on the pile body. Thus, under the elastic force of the spring, the free end of the stabilizing support always tends to open outward and conform to the ground. During the lowering of the soil extraction pile, the stabilizing support unfolds and conforms to the seabed surface under the action of the spring, forming multi-point support for the pile body. As the pile body gradually inserts into the ground under the action of eccentric vibration, the free end of the stabilizing support always remains in close contact with the ground under the pressure of the spring, thereby effectively absorbing the vibration reaction force and keeping the soil extraction pile part as a whole in a vertical and stable posture, preventing the pile body from tilting due to eccentric vibration.

[0013] Furthermore, the main body includes a chassis and a water storage tank. The water storage tank has a water storage chamber inside. One end of the water storage chamber is connected to a hydraulic device. The output end of the hydraulic device is connected to a piston, which drives the piston to move back and forth within the water storage chamber, thereby realizing the water supply and drainage function. The other end of the water storage chamber is connected to a water supply and drainage pipe, which is connected to the water inlet of the chassis. Both ends of the water inlet are equipped with inlet filters to perform secondary filtration on the water flowing into the water storage chamber, preventing fine particles from entering the hydraulic system and causing wear. When the hydraulic device drives the piston to move into the water storage chamber, seawater enters the inlet through the inlet filter and is then sucked into the water storage chamber through the water supply and drainage pipe, achieving sinking counterweight. When the piston moves in the reverse direction, the seawater in the water storage chamber is discharged through the water supply and drainage pipe and the inlet, achieving buoyancy or attitude adjustment.

[0014] Furthermore, the traveling mechanism is connected to the main body via a rotary steering mechanism. The rotary steering mechanism includes a rotating platform driven by a stepper motor, capable of horizontal rotation within a range of 0° to 120°. A propulsion worm is fixed to the lower part of the rotary steering mechanism. The propulsion worm is driven by an independent waterproof motor. When its helical blades rotate, they generate propulsion force with the soft sediment on the seabed. The propulsion worm is fixed to a fixed base, which has a flat plate structure to increase the contact area with the seabed and prevent the device from sinking in soft geological conditions. The propulsion worm, in conjunction with the rotary steering mechanism, enables the underwater sampling platform to move freely forward, backward, and turn under soft geological conditions on the seabed.

[0015] Furthermore, the gripping mechanism includes a robotic arm and a gripping stabilization mechanism. The lower end of the robotic arm is equipped with a rotating base, which is connected to the chassis. The rotating base has a built-in servo motor and reducer, allowing the robotic arm to rotate freely and flexibly around the vertical axis. The robotic arm has a multi-joint structure, with a gripper at its front end. The gripper is driven by a micro servo motor to open and close, used to grip and transfer the soil sampling chamber. There are eight gripping stabilization mechanisms in total, arranged in an alternating pattern on the upper and lower parts of the upper outer shell of the chassis. Each gripping stabilization mechanism includes a pair of gripping arms that can move in opposite directions, with a rubber pad layer on the inner side of the gripping arms. When the robotic arm takes out the soil sampling chamber that has been sampled from the soil sampling pile section, it transfers it to the gripping stabilization mechanism. The gripping arms of the gripping stabilization mechanism move in opposite directions to lock the soil sampling chamber, preventing the soil sampling chamber from falling off or shaking during the movement of the device.

[0016] Accordingly, the present invention also provides a multi-layer sampling method for anti-collapse boreholes in soft seabed geology, employing the aforementioned multi-layer sampling device for anti-collapse boreholes in soft seabed geology, the steps of which are as follows: S1. The underwater sampling platform is lowered to the sea surface by the mother ship. The hydraulic device drives the piston to draw water. After the water storage chamber is filled with water, the device sinks. The underwater sampling device is lowered from the mother ship to the vicinity of the same station via steel cable winch. After the underwater sampling platform reaches the seabed, it moves to the vicinity of the sampling station on the soft geological surface of the seabed through the cooperation of the propulsion worm and the rotation steering mechanism. It meets the underwater sampling device on the seabed and maintains a safe distance. S2. The soil sampling pile is lowered to the predetermined position. The stabilizing support is deployed and placed against the ground under the action of the spring. Then, the eccentric vibration mechanism is activated. The eccentric wheel rotates and generates vibration, which causes the cutting edge at the lower end of the pile to gradually cut into the seabed. During the vibration penetration process, the stabilizing support continuously provides support and alignment to ensure that the pile is inserted into the sediment in a vertical position. After the pile is fully inserted to the predetermined depth, it forms support and protection for the surrounding soft sediment to prevent the hole from collapsing during subsequent sampling. S3. The movable door of the interchangeable opening and closing chamber opens, and the robotic arm takes an empty soil sampling chamber section from the gripping and stabilizing mechanism. It is then placed inside the soil sampling pile section through the window of the interchangeable opening and closing chamber. The movable door closes, and the soil sampling chamber section descends inside the pile body to the working position of the pressing mechanism. The electromagnet is energized and attracts and connects with the electromagnet at the upper end of the soil sampling chamber section. At this time, the closing mechanism is in the closed state, and the closing plate is in a horizontal closed state, keeping the bottom of the soil sampling chamber section closed to prevent foreign objects from entering the chamber during the descent. The motor of the pressing mechanism drives the gear to rotate, and the gear drives the rack to move downward, so that the soil sampling chamber section is pushed down along the inside of the pile body to the predetermined sampling depth. After reaching the predetermined depth, the closing mechanism opens, the closing plate rotates to the vertical state, and the bottom of the soil sampling chamber section is open. After pressing down a certain distance, the sediment sample enters the chamber body, and the original seawater and interstitial water inside the chamber body are discharged from the drain outlet. After the sampling volume is reached, the closing mechanism closes again to seal the bottom of the chamber body, completing the sampling at this depth. S4. Then, the electromagnet of the pressing mechanism is de-energized, the soil sampling chamber separates from the pressing mechanism, the movable door of the interchangeable opening and closing chamber opens, and the robotic arm takes out the soil sampling chamber that has completed sampling from inside the soil sampling pile and transfers it to the idle grasping and stabilizing mechanism on the underwater sampling platform and locks it in place. During this process, the support rod of the cleaning mechanism opens, and the elastic cloth adheres to the inner wall of the pile to carry out the attached loose soil. Excess loose soil is discharged from the soil discharge port on the side wall of the pile. The movable door of the interchangeable opening and closing chamber closes, and the robotic arm takes a new empty soil sampling chamber and puts it into the soil sampling pile through the interchangeable opening and closing chamber. The electromagnet is re-energized to attract the soil, and the pressing mechanism drives the new soil sampling chamber to descend. This time, the descent depth is increased by a predetermined interval compared to the previous one. The above soil sampling operation is repeated. By repeatedly changing the soil sampling chamber and gradually increasing the pressing depth, sampling at different depths can be completed at the same station to obtain a true sequence of stratigraphic samples. S5. After sampling of all predetermined layers is completed, the underwater sampling platform floats up by draining water from the storage chamber. The underwater sampling device is retrieved by the mother ship's winch via steel cable. The operators remove each soil sampling chamber from the grabbing and stabilizing mechanism in sequence, mark the corresponding sampling depth, and then take out sediment samples from each layer for analysis.

[0017] Therefore, the multi-layer sampling device and method for preventing collapse in soft seabed geology of the present invention has at least the following beneficial effects: 1. Strong multi-layer sampling capability: Through the coordinated operation of the underwater sampling platform and the underwater sampling device, the grabbing mechanism can take out the soil sampled in the replacement opening and closing chamber and transfer it to the grabbing stabilizing mechanism on the machine body for temporary storage. At the same time, a new soil sampled in the chamber can be replaced to continue sampling, realizing multiple multi-layer sampling in the same area and effectively restoring the true stratification of sediments.

[0018] 2. Excellent anti-collapse effect: The design of the support pipe combined with the eccentric vibration mechanism ensures that the vibration generated by the rotation of the eccentric wheel promotes the smooth insertion of the support pipe and the cutting edge into the seabed. The support pipe provides support and protection for the surrounding soft sediments, effectively preventing the collapse of the borehole during the sampling process.

[0019] 3. Strong adaptability to soft geological conditions: The bottom of the underwater sampling platform is equipped with a worm gear traveling mechanism, which, together with a rotatable steering mechanism, enables it to move freely within a small range and achieve precise positioning under soft geological conditions on the seabed, adapting to the sampling needs of different areas.

[0020] 4. Low disturbance during sampling: After the support pipe is pre-inserted into the stratum to form an isolation space, the soil sampling chamber completes the soil sampling operation within the isolation space, minimizing disturbance to the sediment samples and improving sampling fidelity.

[0021] 5. Low cost and wide applicability: This device can independently complete sampling operations after being deployed by the mother ship, without the need for a dedicated sampling vessel. It can be used in conjunction with various mother ships, significantly reducing operating costs. Attached Figure Description

[0022] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0023] Figure 1 This is a schematic diagram of the underwater sampling platform of the present invention; Figure 2 This is a schematic cross-sectional view of the internal structure of the chassis of the present invention; Figure 3 This is a schematic diagram of the structure of the inlet filter screen of the present invention; Figure 4 This is a schematic diagram of the bottom cross-section of the body part of the present invention; Figure 5 This is a schematic diagram of the traveling mechanism portion of the present invention; Figure 6 This is a schematic diagram of the upper stabilizing mechanism of the present invention; Figure 7 This is a schematic diagram of the lower stabilizing mechanism of the present invention; Figure 8 This is a schematic diagram of the soil extraction chamber portion of the present invention; Figure 9 This is a cross-sectional schematic diagram of the soil extraction chamber portion of the present invention; Figure 10 This is a schematic diagram of the underwater sampling device of the present invention; Figure 11 This is a schematic diagram of the interchangeable opening and closing compartment of the present invention; Figure 12 This is a schematic diagram of the pressing mechanism of the present invention.

[0024] Explanation of reference numerals in the attached figures: 100 - Body; 110 - Chassis; 111 - Bracket; 112 - Filter plate; 113 - Water inlet; 114 - Water inlet filter screen; 120 - Water tank; 121 - Water storage chamber; 122 - Water supply and drainage pipe; 123 - Piston; 124 - Hydraulic device; 125 - Slide rail; 126 - Rotary resistor; 127 - Positioning slider; 128 - Spiral slide bar; 200 - Traveling mechanism; 210 - Rotary steering mechanism; 220 - Propulsion worm; 230 - Fixed base; 300 - Gripping mechanism; 310 - Robotic arm; 311 - Rotating base; 312 - Gripper; 320 - Gripping stabilizing mechanism; 321 - Upper stabilizing mechanism; 322 - Lower stabilizing mechanism; 400 - Soil intake chamber section; 410 - Electromagnet; 420 - Chamber body; 421 - Drainage outlet; 430 - Closing mechanism; 431 - Hinge; 432 - Closing plate; 440 - Cleaning mechanism; 441 - Support rod; 442 - Elastic cloth; 500 - Soil sampling pile section; 510 - Pile body; 511 - Cutting edge; 512 - Steel cable; 513 - Independent vacuum chamber; 520 - Stabilizing mechanism; 521 - Stabilizing support; 522 - Spring; 530 - Pressing mechanism; 531 - Motor; 532 - Gear; 533 - Rack; 534 - Electromagnet; 540 - Eccentric vibration mechanism; 541 - Eccentric wheel; 550 - Replacement opening and closing chamber; 551 - Opening and closing chamber; 552 - Sliding door; 553 - Guide rail. Detailed Implementation

[0025] Below, in conjunction with Figures 1 to 12This invention provides a detailed description of a multi-layer sampling device and method for preventing collapse in soft seabed geology.

[0026] Depend on Figures 1 to 12 As shown, the multi-layer sampling device for preventing collapse of seabed soft geology of the present invention mainly includes two parts: an underwater sampling platform and an underwater sampling device.

[0027] The underwater sampling platform is used for seabed positioning and for the storage and transfer of the soil sampling chamber 400. The underwater sampling device is lowered to the predetermined station via the mother ship's steel cable. It is used for the penetration of the support pipe (soil sampling pile 500) and the sequential sampling of the soil sampling chamber 400. The two main parts are deployed independently and work together to complete the multi-layer sampling operation of the soft seabed geology.

[0028] The underwater sampling platform includes a main body 100 and a traveling mechanism 200. The main body 100 includes a casing 110 and a water tank 120. Filter plates 112 are installed on the front and rear sides of the casing 110 to prevent larger impurities from entering the main body and clogging the water passages. A support frame 111 is installed inside the casing 110 to support and secure the water tank 120, ensuring its stability during changes in the device's orientation. The water storage tank 120 has a water storage chamber 121 inside. One end of the water storage chamber 121 is connected to a hydraulic device 124. The output end of the hydraulic device 124 is connected to a piston 123 and can drive the piston 123 to move back and forth in the water storage chamber 121, thereby realizing the water supply and drainage function. The other end of the water storage chamber 121 is connected to a water supply and drainage pipe 122. The water supply and drainage pipe 122 is connected to the water inlet 113 of the casing 110. Both ends of the water inlet 113 are equipped with water inlet filter screens 114 to perform secondary filtration on the water flowing into the water storage chamber 121, preventing fine particles from entering the hydraulic system and causing wear. When the hydraulic device 124 drives the piston 123 to move into the water storage chamber 121, seawater enters the inlet 113 through the inlet filter screen 114 and is then sucked into the water storage chamber 121 through the water supply and drainage pipe 122, achieving a sinking counterweight. When the piston 123 moves in the opposite direction, the seawater in the water storage chamber 121 is discharged through the water supply and drainage pipe 122 and the inlet 113, achieving buoyancy or attitude adjustment.

[0029] The upper end of the water storage tank 120 is provided with a slide rail 125, and a positioning slider 127 is provided on the slide rail 125. The positioning slider 127 can slide freely along the slide rail 125. A rotating resistor 126 is fixed to one end of the water storage tank 120. A spiral slide bar 128 is connected to the rotating shaft of the rotating resistor 126. The spiral slide bar 128 passes through a mating hole opened on the positioning slider 127. When the piston 123 moves under the drive of the hydraulic device 124, the positioning slider 127 moves synchronously with the piston 123 through magnetic linkage. The positioning slider 127 is embedded with a permanent magnet, and a permanent magnet is also embedded at the corresponding position on the piston 123. The two have opposite polarities and form magnetic coupling, so that when the piston 123 moves, it drives the positioning slider 127 to move synchronously on the slide rail 125. When the positioning slider 127 moves, it drives the spiral slide bar 128 to rotate. The spiral slide bar 128 then drives the rotating shaft of the rotating resistor 126 to rotate, causing the resistance value to change linearly. By measuring the change in this resistance value, the real-time water storage volume in the water storage tank 120 can be accurately determined, thereby achieving precise water supply and drainage control and avoiding loss of control of the device posture due to excessive water supply or drainage.

[0030] The traveling mechanism 200 is fixed below the chassis 110 and connected to the body 100 via a rotary steering mechanism 210. The rotary steering mechanism 210 includes a rotating platform driven by a stepper motor, capable of horizontal rotation within a range of 0° to 120°. A propulsion worm 220 is fixed to the lower part of the rotary steering mechanism 210. Driven by an independent waterproof motor, the propulsion worm 220 generates propulsion force by rotating its helical blades against soft seabed sediment. The propulsion worm 220 is fixed to a fixed base 230, which has a flat plate structure to increase the contact area with the seabed and prevent the device from sinking in soft geological conditions. The propulsion worm 220, in conjunction with the rotary steering mechanism 210, enables the underwater sampling platform to move freely forward, backward, and turn in soft seabed conditions, thus achieving precise multi-point positioning within a small area after the mother ship's initial positioning.

[0031] A gripping mechanism 300 is connected to the upper part of the main body 100. The gripping mechanism 300 includes a robotic arm 310 and a gripping stabilizing mechanism 320. The lower end of the robotic arm 310 is provided with a rotating base 311, which is connected to the housing 110. The rotating base 311 has a built-in servo motor and reducer, allowing the robotic arm 310 to rotate freely and flexibly around a vertical axis. The robotic arm 310 has a multi-joint structure, and its front end is provided with a gripper 312. The gripper 312 is driven by a micro servo motor and can realize opening and closing actions for gripping and transferring the soil collection chamber 400.

[0032] There are eight gripping and stabilizing mechanisms 320, arranged in a staggered pattern on the upper and lower parts of the upper outer shell of the housing 110. Each gripping and stabilizing mechanism 320 includes a pair of gripping arms that can move in opposite directions, and the inner side of the gripping arms is provided with a rubber pad. After the robotic arm 310 removes the sampled soil collection chamber 400 from the replacement opening and closing chamber 550 of the soil collection pile section 500, it transfers it to the gripping and stabilizing mechanism 320. The gripping arms of the gripping and stabilizing mechanism 320 move in opposite directions to lock the soil collection chamber 400, preventing the soil collection chamber 400 from falling off or shaking during the movement of the device.

[0033] The underwater sampling device mainly consists of a sampling pile section 500 (support pipe). The pile body 510 of the sampling pile section 500 is a hollow cylindrical structure with a cutting edge 511 at its lower end. The cutting edge 511 has a beveled design to facilitate smooth cutting into the seabed under eccentric vibration. A steel cable 512 is connected to the upper end of the pile body 510. One end of the steel cable 512 is fixedly connected to the pile body 510 by a shackle, and the other end extends upward and connects to the winch system of the mother ship. The sampling pile section 500 is lowered and retrieved underwater by the raising and lowering of the mother ship's winch.

[0034] A stabilizing mechanism 520 is provided on the outside of the soil extraction pile section 500. The stabilizing mechanism 520 includes multiple stabilizing supports 521, which are evenly distributed around the circumference of the pile body 510. One end of each stabilizing support 521 is hinged to the pile body 510, and the other end is a free end. The sliding block slides on a linear guide rail provided on the outer wall of the pile body 510. The stabilizing support 521 is connected to the pile body 510 by a spring 522. The spring 522 is sleeved on the outside of the linear guide rail, with one end abutting against the stabilizing support 521 and the other end abutting against the limiting boss on the pile body 510. Thus, under the elastic force of the spring 522, the free end of the stabilizing support 521 always tends to open outward and conform to the ground. During the lowering of the soil extraction pile 500, the stabilizing support 521 unfolds and fits against the seabed under the action of the spring 522, providing multi-point support for the pile body 510. As the pile body 510 gradually inserts into the ground under the action of eccentric vibration, the free end of the stabilizing support 521 remains in close contact with the ground under the pressure of the spring 522, thereby effectively absorbing the vibration reaction force and keeping the soil extraction pile 500 in a vertical and stable posture, preventing the pile body 510 from tilting due to eccentric vibration.

[0035] The upper part of the soil sampling pile section 500 is equipped with an independent vacuum chamber 513, which is a sealed cavity structure containing an eccentric vibration mechanism 540. The eccentric vibration mechanism 540 includes an eccentric wheel 541 driven by a waterproof motor. The center of mass distribution of the eccentric wheel 541 is offset from its axis of rotation. When the waterproof motor drives the eccentric wheel 541 to rotate at high speed, it generates periodic centrifugal force. This centrifugal force is transmitted to the pile body 510, causing the entire soil sampling pile section 500 to produce a slight, high-frequency, low-amplitude vibration. This vibration causes the cutting edge 511 at the lower end of the pile body 510 to gradually cut into the seabed sediment, allowing the pile body 510 to be smoothly inserted into the ground. The independent vacuum chamber 513 isolates the eccentric vibration mechanism 540 from the external seawater, ensuring its normal operating environment, and also prevents excessive dissipation of vibration energy into the seawater, ensuring that the vibration energy is concentrated and transmitted to the lower end of the pile body 510.

[0036] The soil sampling pile section 500 is equipped with a pressing mechanism 530. The pressing mechanism 530 includes a motor 531, a gear 532, a rack 533, and an electromagnet 534. The motor 531 is fixedly mounted on the upper support inside the soil sampling pile section 500, and its output shaft is connected to the gear 532. The gear 532 meshes with the rack 533, which extends vertically, and its lower end is fixedly connected to the electromagnet 534. When the motor 531 drives the gear 532 to rotate, the gear 532 drives the rack 533 to move vertically, thereby providing a downward linear thrust to the electromagnet 534 and the soil sampling chamber section 400 connected to it. The stroke of the pressing mechanism 530 can be controlled in real time by an encoder, thereby precisely controlling the pressing depth of the soil sampling chamber section 400 and achieving stratified sampling at different depths.

[0037] The upper side wall of the soil extraction pile 500 is equipped with a replacement opening and closing chamber 550, located below the independent vacuum chamber 513 and at the window opened in the side wall of the pile body 510. The replacement opening and closing chamber 550 includes an opening and closing chamber 551, a sliding door 552, and a guide rail 553. The opening and closing chamber 551 is integrated with the side wall of the pile body 510, forming an internal receiving space. This receiving space is connected to or isolated from the hollow area inside the pile body 510 through the opening and closing of the sliding door 552. The guide rail 553 is fixed horizontally to the upper and lower sides of the opening and closing chamber 551. The sliding door 552 is embedded in the guide rail 553 and can be driven by a micro motor to slide horizontally on the guide rail 553, thereby realizing the opening and closing of the window of the opening and closing chamber 551. When it is necessary to put in or take out the soil sampling chamber 400, the movable door 552 is opened. When the soil sampling operation is carried out, the movable door 552 is closed to prevent external sediments or seawater from entering the pile body 510 and interfering with the sampling.

[0038] The soil sampling chamber 400 includes an electromagnet 410, a chamber body 420, a closing mechanism 430, and a cleaning mechanism 440. The chamber body 420 is a cylindrical container with an open top, used to hold the collected sediment samples. An electromagnet 410 is fixed to the upper end of the chamber body 420. The electromagnet 410 has a ring structure. When energized, it generates magnetic force, which attracts the opposite magnetic poles of the electromagnet 534 at the lower part of the pressing mechanism 530, thereby achieving a tight magnetic adsorption connection. When the electromagnet 534 is de-energized or the current direction is changed, the magnetic force disappears or reverses, and the soil sampling chamber 400 separates from the pressing mechanism 530. The upper side wall of the chamber 420 is provided with a drainage port 421. The drainage port 421 consists of multiple through holes evenly distributed along the circumference of the chamber 420. During the soil sampling process, the sediment sample enters the chamber from the lower end of the chamber 420. The original seawater inside the chamber 420 and the interstitial water carried in the sample can be discharged from the drainage port 421, thereby reducing the pressure inside the chamber 420 and preventing the sample from being unable to enter normally or the sample sequence from being compressed and destroyed due to pressure accumulation.

[0039] The closing mechanism 430 is located at the lower end inside the chamber 420 and includes a hinge 431 and closing plates 432. The closing plates 432 are multi-triangular structures, and multiple closing plates 432 are connected to the lower periphery of the inner wall of the chamber 420 via the hinge 431. During soil sampling, the closing mechanism 430 is in the open state, and the closing plates 432 are vertically attached to the inner wall of the chamber 420 under the action of gravity or elastic elements, without obstructing the entry of sediment. After soil sampling is completed, the closing plates 432 are rotated to a horizontal state by the torsion spring built into the hinge 431 or by electromagnetic drive. Multiple closing plates 432 are assembled to form a closed circular bottom surface, sealing the bottom of the chamber 420 and preventing the sample from falling off during transfer.

[0040] The cleaning mechanism 440 is located outside the silo body 420 and includes a support rod 441 and an elastic cloth 442. The support rod 441 consists of multiple elastic rods hinged circumferentially along the outer wall of the silo body 420. The free end of the support rod 441 is connected to an annular elastic cloth 442, which is fitted onto the outer wall of the silo body 420 and can slide up and down along the outer wall. When the soil-borrowing silo part 400 is removed from the soil-borrowing pile part 500, the support rod 441 expands outward under its own elasticity, causing the elastic cloth 442 to expand outward and adhere to the inner wall of the pile body 510. As the soil-borrowing silo part 400 is lifted, the elastic cloth 442 slides tightly against the inner wall of the pile body 510, scraping away and removing the loose soil adhering to the inner wall of the pile body 510. The lower middle part of the pile body 510 is provided with a soil discharge port. Excess loose soil carried out by the elastic cloth 442 can be discharged from the outside of the pile body 510 through the soil discharge port, thereby keeping the internal environment of the pile body 510 clean and reducing the pollution interference of residual loose soil to the next sampling sample.

[0041] The following describes the steps of the multi-layer sampling method for preventing collapse in soft seabed geology according to the present invention, in conjunction with this device: The underwater sampling platform is lowered to the sea surface by the mother ship. Hydraulic device 124 drives piston 123 to draw in water. After the water storage chamber 121 is filled with water, the platform sinks. The underwater sampling device is then lowered from the mother ship via steel cable 512 to a location near the sampling station. After reaching the seabed, the underwater sampling platform moves along the soft geological surface of the seabed to the vicinity of the sampling station through the cooperation of propulsion worm gear 220 and rotary steering mechanism 210, meeting the underwater sampling device on the seabed and maintaining a safe distance.

[0042] The soil sampling pile 500 is lowered to the predetermined position. The stabilizing support 521 unfolds and fits against the ground under the action of the spring 522. Then, the eccentric vibration mechanism 540 is activated. The eccentric wheel 541 rotates and generates vibration, causing the cutting edge 511 at the lower end of the pile 510 to gradually cut into the seabed. During the vibration penetration process, the stabilizing support 521 continuously provides support and straightens the pile 510 to ensure that it is inserted into the sediment in a vertical position. After the pile 510 is fully inserted to the predetermined depth, it forms support and protection for the surrounding soft sediment, preventing the hole from collapsing during subsequent sampling.

[0043] The movable door 552 of the interchangeable opening and closing chamber 550 is opened, and the robotic arm 310 takes an empty soil-collecting chamber section 400 from the gripping and stabilizing mechanism 320 and puts it into the soil-collecting pile section 500 through the window of the interchangeable opening and closing chamber 550. The movable door 552 is closed, and the soil-collecting chamber section 400 is lowered inside the pile body 510 to the working position of the pressing mechanism 530. The electromagnet 534 is energized and is attracted and connected to the electromagnet 410 at the upper end of the soil-collecting chamber section 400. At this time, the closing mechanism 430 is in the closed state, and the closing plate 432 is in a horizontal closed state, keeping the bottom of the soil sampling chamber 400 closed to prevent foreign objects from entering the chamber 420 during the descent. The motor 531 of the pressing mechanism 530 drives the gear 532 to rotate, and the gear 532 drives the rack 533 to move downward, so that the soil sampling chamber 400 is pushed down along the inside of the pile body 510 to the predetermined sampling depth. After reaching the predetermined depth, the closing mechanism 430 opens, the closing plate 432 rotates to the vertical state, and the bottom of the soil sampling chamber 400 is open. After pressing down a certain distance, the sediment sample enters the chamber 420. The original seawater and interstitial water inside the chamber 420 are discharged from the drain outlet 421. After the sampling volume is reached, the closing mechanism 430 closes again to seal the bottom of the chamber 420, completing the sampling at this depth.

[0044] Then, the electromagnet 534 of the pressing mechanism 530 is de-energized, the soil sampling chamber 400 separates from the pressing mechanism 530, the moving door 552 of the interchangeable opening and closing chamber 550 opens, and the robotic arm 310 takes out the soil sampling chamber 400 that has completed sampling from inside the soil sampling pile 500 and transfers it to the idle grasping and stabilizing mechanism 320 on the underwater sampling platform and locks it in place. During this process, the support rod 441 of the cleaning mechanism 440 opens, and the elastic cloth 442 adheres to the inner wall of the pile body 510 to carry out the attached loose soil. The excess loose soil is discharged from the soil discharge port on the side wall of the pile body 510. The movable door 552 of the replacement opening and closing chamber 550 closes, and the robotic arm 310 picks up the new empty soil sampling chamber section 400 and places it into the soil sampling pile section 500 through the replacement opening and closing chamber 550. The electromagnet 534 is re-energized to attract the soil, and the pressing mechanism 530 drives the new soil sampling chamber section 400 to descend. This descent depth is increased by a predetermined interval compared to the previous one. The above soil sampling operation is repeated. By repeatedly replacing the soil sampling chamber section 400 and gradually increasing the pressing depth, different depth layers can be sampled sequentially at the same station to obtain a true sequence of stratigraphic samples.

[0045] After sampling of all predetermined layers is completed, the underwater sampling platform floats up by draining water from the water storage chamber 121. The underwater sampling device is retrieved by the mother ship winch via steel cable 512. The operators remove each soil sampling chamber 400 from the grabbing and stabilizing mechanism 320 in sequence, mark the corresponding sampling depth, and then take out sediment samples from each layer for analysis.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any transformations or substitutions that can be understood by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention.

Claims

1. A multi-layer sampling device for preventing collapse in soft seabed geology, characterized in that, include: The underwater sampling platform includes a body part (100), a traveling mechanism part (200) fixed below the body part (100), and a gripping mechanism part (300) connected above the body part (100), for walking and positioning on the seabed and for storing and transporting the soil hopper part (400). The underwater sampling device includes a soil sampling pile (500), which is lowered to a predetermined station via a mother ship's steel cable for the penetration of the soil sampling pile (500) and the sequential sampling of the soil sampling chamber (400). The pile body (510) of the soil extraction pile part (500) is a hollow cylindrical structure with a cutting edge (511) at its lower end. The soil extraction pile part (500) is provided with a stabilizing mechanism (520) on its exterior. The stabilizing mechanism (520) includes a plurality of stabilizing supports (521) evenly distributed along the circumference of the pile body (510). One end of each stabilizing support (521) is hinged to a sliding block that slides on a linear guide rail provided on the outer wall of the pile body (510), and the other end is a free end. The upper part of the soil sampling pile (500) is provided with an independent vacuum chamber (513), and the interior of the independent vacuum chamber (513) is provided with an eccentric vibration mechanism (540) to make the soil sampling pile (500) generate high-frequency low-amplitude vibration, so that the cutting edge (511) at the lower end of the pile body (510) gradually cuts into the seabed sediment, so that the pile body (510) is smoothly inserted into the ground. The soil sampling pile section (500) is provided with a pressing mechanism (530). The pressing mechanism (530) includes a motor (531) fixedly installed on the upper support inside the soil sampling pile section (500), a gear (532) connected to the output shaft of the motor (531), and a rack (533) meshing with the gear (532). The rack (533) extends vertically and its lower end is fixedly connected to an electromagnet (534). The soil sampling chamber (400) includes a chamber (420) for accommodating the collected sediment samples, an electromagnet (410) fixed to the upper end of the chamber (420), a closing mechanism (430) located at the lower end of the chamber (420), and a cleaning mechanism (440) located outside the chamber (420) to scrape and remove loose soil adhering to the inner wall of the pile (510). When the electromagnet (410) is energized, it generates magnetic force and attracts the opposite magnetic poles of the electromagnet (534) at the lower part of the pressing mechanism (530).

2. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 1, characterized in that, The closing mechanism (430) includes a hinge (431) and a closing plate (432). The closing plate (432) is a multi-triangular structure. Multiple closing plates (432) are connected to the lower periphery of the inner wall of the chamber (420) through the hinge (431). When the soil is taken, the closing mechanism (430) is in the open state. Under the action of gravity or elastic element, the closing plate (432) is in a state of vertically adhering to the inner wall of the chamber (420) and does not hinder the entry of sediment. After the soil is taken, the closing plate (432) is rotated to a horizontal state by the torsion spring built into the hinge (431) or electromagnetic drive. Multiple closing plates (432) are spliced ​​together to form a closed circular bottom surface, which seals the bottom of the chamber (420) and prevents the sample from falling off during the transfer process.

3. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 2, characterized in that, The cleaning mechanism (440) includes a support rod (441) and an elastic cloth (442). The support rod (441) consists of multiple elastic rods that are hinged circumferentially along the outer wall of the chamber (420). The free end of the support rod (441) is connected to an annular elastic cloth (442). The elastic cloth (442) is sleeved on the outer wall of the chamber (420) and can slide up and down along the outer wall. When the soil sampling chamber (400) is removed from the soil sampling pile (500), the support rod (441) opens outward under its own elasticity, causing the elastic cloth (442) to expand outward and adhere to the inner wall of the pile body (510). As the soil sampling chamber (400) is lifted, the elastic cloth (442) slides tightly against the inner wall of the pile body (510), scraping off and carrying away the loose soil attached to the inner wall of the pile body (510). The middle and lower part of the pile body (510) is provided with a soil discharge port. The excess loose soil carried out by the elastic cloth (442) can be discharged from the outside of the pile body (510) through the soil discharge port, thereby keeping the internal environment of the pile body (510) clean and reducing the pollution interference of residual loose soil to the next sampling sample.

4. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 3, characterized in that, The upper side wall of the soil extraction pile (500) is provided with a replacement opening and closing chamber (550), which is located below the independent vacuum chamber (513) and at the window opened on the side wall of the pile body (510). The interchangeable opening and closing chamber (550) includes an opening and closing chamber (551), a movable door (552), and a guide rail (553). The opening and closing chamber (551) is integrated with the side wall of the pile body (510), forming an internal accommodating space. This accommodating space is connected to or isolated from the hollow area inside the pile body (510) by opening and closing the movable door (552). The guide rail (553) is fixed horizontally on the upper and lower sides of the opening and closing chamber (551). The movable door (552) is embedded in the guide rail (553) and is driven by a micro motor to slide horizontally on the guide rail (553), thereby realizing the opening and closing of the window of the opening and closing chamber (551). When it is necessary to put in or take out the soil sampling chamber (400), the movable door (552) is opened. When the soil sampling operation is performed, the movable door (552) is closed to prevent external sediments or seawater from entering the pile body (510) and interfering with the sampling.

5. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 4, characterized in that, The stabilizing bracket (521) is connected to the pile body (510) by a spring (522). The spring (522) is sleeved on the outside of the linear guide rail, with one end abutting against the stabilizing bracket (521) and the other end abutting against the limiting boss on the pile body (510). Thus, under the elastic force of the spring (522), the free end of the stabilizing bracket (521) always tends to open outward and fit against the ground. During the lowering of the soil extraction pile (500), the stabilizing support (521) unfolds and fits against the seabed under the action of the spring (522), forming multi-point support for the pile body (510). When the pile body (510) is gradually inserted into the ground under the action of eccentric vibration, the free end of the stabilizing support (521) always remains in close contact with the ground under the pressure of the spring (522), thereby effectively absorbing the vibration reaction force and keeping the soil extraction pile (500) in a vertical and stable posture, preventing the pile body (510) from tilting due to eccentric vibration.

6. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 5, characterized in that, The main body (100) includes a chassis (110) and a water storage tank (120). The water storage tank (120) has a water storage chamber (121) inside. One end of the water storage chamber (121) is connected to a hydraulic device (124). The output end of the hydraulic device (124) is connected to a piston (123) and drives the piston (123) to move back and forth in the water storage chamber (121) to realize the water supply and drainage function. The other end of the water storage chamber (121) is connected to a water supply and drainage pipe (122). The water supply and drainage pipe (122) is connected to the water inlet (113) of the chassis (110). The two ends of the water inlet (113) are provided with water inlet filter screens (114) to perform secondary filtration on the water flow entering the water storage chamber (121) to prevent fine particles from entering the hydraulic system and causing wear. When the hydraulic device (124) drives the piston (123) to move into the water storage chamber (121), seawater enters the inlet (113) through the inlet filter screen (114) and is then sucked into the water storage chamber (121) through the water supply and drainage pipe (122) to achieve sinking counterweight. When the piston (123) moves in the opposite direction, the seawater in the water storage chamber (121) is discharged through the water supply and drainage pipe (122) and the inlet (113) to achieve floating or attitude adjustment.

7. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 6, characterized in that, The traveling mechanism (200) is connected to the body (100) via a rotary steering mechanism (210). The rotary steering mechanism (210) includes a rotating platform driven by a stepper motor, which can achieve horizontal rotation in the range of 0° to 120°. The lower part of the rotary steering mechanism (210) is fixed with a propulsion worm (220). The propulsion worm (220) is driven by an independent waterproof motor. When its spiral blades rotate, they generate propulsion force with the soft sediment on the seabed. The propulsion worm (220) is fixed on a fixed base (230). The fixed base (230) has a flat plate structure, which increases the contact area with the seabed and prevents the device from sinking in soft geological conditions. The propulsion worm (220) works in conjunction with the rotary steering mechanism (210) to enable the underwater sampling platform to move forward, backward and turn freely under soft geological conditions on the seabed.

8. The multi-layer sampling device for preventing collapse in soft seabed geology according to claim 7, characterized in that, The gripping mechanism (300) includes a robotic arm (310) and a gripping stabilizing mechanism (320). The lower end of the robotic arm (310) is provided with a rotating base (311). The rotating base (311) is connected to the chassis (110). The rotating base (311) has a built-in servo motor and reducer, which allows the robotic arm (310) to rotate freely and flexibly around the vertical axis. The robotic arm (310) is a multi-joint structure with a gripper (312) at its front end. The gripper (312) is driven by a micro servo motor to open and close, and is used to grip and transfer the soil collection chamber (400). There are eight gripping and stabilizing mechanisms (320) in total, which are arranged in an alternating manner on the upper and lower parts of the upper shell of the chassis (110). Each gripping and stabilizing mechanism (320) includes a pair of gripping arms that can move in opposite directions. The inner side of the gripping arms is provided with a rubber pad. When the robotic arm (310) takes out the soil sampled section (400) from the replacement opening and closing chamber (550) of the soil sampled pile section (500), it transfers it to the gripping and stabilizing mechanism (320). The gripping arms of the gripping and stabilizing mechanism (320) move in opposite directions to lock the soil sampled section (400) to prevent the soil sampled section (400) from falling off or shaking during the movement of the device.

9. A method for multi-layer sampling of seabed soft geology using the apparatus described in claim 8, characterized in that, The steps are as follows: S1. The underwater sampling platform is hoisted to the sea surface by the mother ship. The hydraulic device (124) drives the piston (123) to draw water. After the water storage chamber (121) is filled with water, the device sinks. The underwater sampling device is lowered from the mother ship winch to the vicinity of the same station via steel cable (512). After the underwater sampling platform reaches the seabed, it moves to the vicinity of the sampling station on the soft geological surface of the seabed through the cooperation of the propulsion worm (220) and the rotation steering mechanism (210), and meets the underwater sampling device on the seabed and maintains a safe distance. S2. The soil sampling pile (500) is lowered to the predetermined station. The stabilizing support (521) unfolds and fits against the ground under the action of the spring (522). Then, the eccentric vibration mechanism (540) is activated. The eccentric wheel (541) rotates and generates vibration, causing the cutting edge (511) at the lower end of the pile (510) to gradually cut into the seabed. During the vibration penetration process, the stabilizing support (521) continuously provides support and straightening to ensure that the pile (510) is inserted into the sediment in a vertical posture. After the pile (510) is completely inserted to the predetermined depth, it forms support and protection for the surrounding soft sediment to prevent the hole from collapsing during subsequent sampling. S3. The movable door (552) of the interchangeable opening and closing chamber (550) opens, and the robotic arm (310) takes an empty soil sampling chamber section (400) from the gripping and stabilizing mechanism (320) and places it into the soil sampling pile section (500) through the window of the interchangeable opening and closing chamber (550). The movable door (552) closes, and the soil sampling chamber section (400) descends inside the pile body (510) to the working position of the pressing mechanism (530). The electromagnet (534) is energized and attracts and connects with the electromagnet (410) at the upper end of the soil sampling chamber section (400). At this time, the closing mechanism (430) is in the closed state, and the closing plate (432) is in a horizontal closed state, keeping the bottom of the soil sampling chamber section (400) closed to prevent foreign objects from entering during the descent. The sample is inserted into the chamber (420). The motor (531) of the pressing mechanism (530) drives the gear (532) to rotate. The gear (532) drives the rack (533) to move downward, so that the soil sampling chamber (400) is pushed down along the inside of the pile (510) to the predetermined sampling depth. After reaching the predetermined depth, the closing mechanism (430) opens, and the closing plate (432) rotates to the vertical position. The bottom of the soil sampling chamber (400) is open. After pressing down a certain distance, the sediment sample enters the chamber (420). The original seawater and interstitial water inside the chamber (420) are discharged from the drain (421). After the sampling amount is reached, the closing mechanism (430) closes again to seal the bottom of the chamber (420), completing the sampling at this depth. S4. Then the electromagnet (534) of the pressing mechanism (530) is de-energized, the soil sampling chamber (400) separates from the pressing mechanism (530), the moving door (552) of the interchangeable opening and closing chamber (550) opens, and the robotic arm (310) takes out the soil sampling chamber (400) that has completed sampling from inside the soil sampling pile (500), and transfers it to the idle grasping and stabilizing mechanism (320) on the underwater sampling platform and locks it in place. During this process, the support rod (441) of the cleaning mechanism (440) opens, and the elastic cloth (442) adheres to the inner wall of the pile body (510) to carry out the attached loose soil. Excess loose soil is removed from the pile body (510). 0) Soil is discharged from the side wall outlet; the moving door (552) of the replacement opening and closing chamber (550) is closed, the robotic arm (310) takes the new empty soil sampling chamber part (400) and puts it into the soil sampling pile part (500) through the replacement opening and closing chamber (550), the electromagnet (534) is re-energized and attracted, and the pressing mechanism (530) drives the new soil sampling chamber part (400) to descend. The descent depth this time is increased by a predetermined interval compared with the previous time. The above soil sampling operation is repeated. By repeatedly replacing the soil sampling chamber part (400) and increasing the pressing depth step by step, sampling at different depth levels can be completed at the same station to obtain a real sequence of strata samples. S5. After sampling of all predetermined layers is completed, the underwater sampling platform floats up by draining water from the water storage chamber (121). The underwater sampling device is retrieved by the mother ship winch via steel cable (512). The operator removes each soil sampling chamber (400) from the grabbing and stabilizing mechanism (320) in sequence, marks the corresponding sampling depth, and then takes out sediment samples from each layer for analysis.

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