Dynamic rotary shear testing device and method for evaluating crawler-soil shear action of deep-sea mining crawler

Abstract

The invention relates to a dynamic rotary shear testing device and a dynamic rotary shear testing method for evaluating a crawler-soil shear effect of a deep-sea mining crawler. Comprising a four-state environmental control system which is composed of different-state soil and an annular structure and simulates the surface characteristics of deep-sea soft soil in transition from a flow state to a plastic shape along with depth increase; the soil stress simulation system is composed of an air bag and a sand cushion layer and accurately reproduces the stress state of the crawler teeth in the deep sea environment; the soil body loading system is composed of a sand cushion layer, an air bag and a high-pressure air cylinder and is used for simulating deep sea soil environments with different burial depths; the track tooth dynamic rotary shear test system is composed of a blade, a torsion bar and a variable frequency motor, and simulates the influence of multiple types of track teeth on the shear strength of deep sea soil; and the data acquisition system consists of a pressure sensor and a dynamic torque sensor. According to the invention, the shear failure process of multiple types of crawler teeth to soil under different deep-sea working conditions is simulated with high precision, the device is simple and easy to operate, and technical support is provided for design optimization of a deep-sea crawler and a crawler-soil action mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of deep - sea mining, and specifically, to a dynamic rotary shear test device and method for evaluating the shear action between the track and soil of a deep - sea mining tracked vehicle. Background Art

[0002] With the increasing depletion of land resources, the development and utilization of seabed mineral resources have become the focus of global attention. In China, the research on deep - sea mining technology started relatively late and mainly focused on the overall design of deep - sea mining systems. Among them, the mining vehicle that undertakes the tasks of walking, collecting, and transporting on the seabed is the core equipment of the entire seabed operation system, and the track is the key component to ensure the continuous, safe, and efficient operation of the vehicle body on deep - sea sediments.

[0003] Deep - sea sedimentary soil exhibits unique physical and mechanical properties under high - pressure and high - salt environments, such as low shear strength and obvious rheological properties, which are significantly different from most terrestrial soils and shallow - sea soils. When the mining vehicle travels on the seabed, the torque generated by the engine is transmitted to the deep - sea sedimentary soil through the track, and shear action occurs at the interface between the track teeth and the sedimentary soil.

[0004] The geometric parameters of the track teeth, such as the height, shape, and speed of the track teeth, directly affect the shear mechanism of the track teeth on the deep - sea sedimentary soil, and then change the failure mode of the deep - sea sedimentary soil, resulting in a significant decrease in the traction force provided, making it difficult for the mining vehicle to travel and even possibly causing serious consequences such as slipping or overturning.

[0005] Therefore, developing a dynamic rotary shear test device and method that can simulate the evaluation of the shear action between the track and soil of a deep - sea mining tracked vehicle and studying the influence of different track - tooth geometric parameters on the shear strength of deep - sea sedimentary soil has important theoretical value and engineering significance. Through this research, a scientific basis can be provided for the track design and operation parameter optimization of deep - sea mining vehicles, and the adaptability and operation efficiency of mining vehicles in complex seabed environments can be improved. Summary of the Invention

[0006] To overcome the deficiencies of the prior art, the present invention provides a dynamic rotary shear test device and method for evaluating the shear action between the track and soil of a deep - sea mining tracked vehicle, aiming to accurately simulate the shear action between the track teeth and the deep - sea sedimentary soil and provide technical means and a scientific basis for the design and optimization of tracked vehicles.

[0007] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions:

[0008] A dynamic rotary shear test device and method for evaluating the shear action between the track and soil of a deep-sea mining crawler vehicle. The test device mainly includes a four-state environmental control system, a soil stress simulation system, a soil loading system, a track tooth dynamic rotary shear test system, and a data acquisition system. The four-state environmental control system consists of simulated soil in four different states and a ring structure, simulating the surface characteristics of deep-sea soft soil transitioning from a fluid state to a plastic state with increasing depth; the soil stress simulation system consists of four sidewall airbags, a bottom center airbag, and a top sand cushion layer, accurately reproducing the stress state of the track teeth in the deep-sea environment; the soil loading system consists of a top sand cushion layer surcharge, four sidewall airbags, a bottom center airbag, and a high-pressure gas cylinder, simulating the deep-sea soil environment at different burial depths; the track tooth dynamic rotary shear test system consists of blades, torsion bars, and variable-frequency motors, simulating the influence of various types of track teeth on the shear strength of deep-sea soil; the data acquisition system consists of pressure sensors and dynamic torque sensors. Based on the test device, a multi-step test method is used to accurately simulate the shear failure process of various types of track teeth on soil under different deep-sea working conditions.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. High degree of simulation: The test device can accurately simulate the shear process of track teeth on deep-sea sedimentary soil when the mining vehicle is walking under actual working conditions, providing reliable data support for the design of crawler vehicles;

[0011] 2. Multi-parameter research: The test device can study the influence of different shear rates, track tooth heights, and track tooth shapes on the shear effect of deep-sea sedimentary soil, providing a theoretical basis for optimizing the performance of crawler vehicles;

[0012] 3. Wide applicability: The method of the present invention is not only applicable to the field of deep-sea mining, but can also be widely applied to the research of geotechnical mechanical properties in fields such as civil engineering, hydropower engineering, transportation engineering, and energy development, and has broad application prospects. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the abstract drawing of the dynamic rotary shear test device for evaluating the shear action between the track and soil of a deep-sea mining crawler vehicle.

[0014] Figure 2 It is a schematic diagram of the front view of the dynamic rotary shear test device for evaluating the shear action between the track and soil of a deep-sea mining crawler vehicle.

[0015] Figure 3 It is a schematic diagram of the left view of the dynamic rotary shear test device for evaluating the shear action between the track and soil of a deep-sea mining crawler vehicle.

[0016] Figure 4 It is a schematic diagram of the top view of the dynamic rotary shear test device for evaluating the shear action between the track and soil of a deep-sea mining crawler vehicle.

[0017] In the figure: 1. Airbag 1, 2. Airbag 2, 3. Airbag 3, 4. Airbag 4, 5. Pressure sensor 1, 6. Pressure sensor 2, 7. Pressure sensor 3, 8. Pressure sensor 4, 9. Vane 1, 10. Vane 2, 11. Vane 3, 12. Vane 4, 13. Pressure sensor 5, 14. Pressure sensor 6, 15. Pressure sensor 7, 16. Pressure sensor 8, 17. Torsion bar, 18. Airbag 5, 19. Sand cushion layer, 20. Device plate.

[0018] Figure 5 It is a schematic diagram for the force analysis of vane 1 in the test device.

[0019] Figure 6 It is a schematic diagram of the grounding pressure at different positions when the mining vehicle is moving under actual working conditions.

[0020] In the figure: 21. Driving wheel, 22. Track tooth, 23. Idler wheel, 24. Crawler belt, 25. Driven wheel.

[0021] Figure 7 It is a schematic diagram of the effect of the side wall 1 of the track tooth when the mining vehicle is moving under actual working conditions.

[0022] Figure 8 It is a schematic diagram of the effect of the side wall 2 of the track tooth when the mining vehicle is moving under actual working conditions.

[0023] Figure 9 It is a schematic diagram of different track tooth shapes. Specific implementation mode

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] This test device includes a soil sample container, a pressurizing airbag, a torsion bar, vanes, a sand cushion layer, a test plate and pressure sensors. The soil sample container consists of four annular structures, the height of each ring is 50 mm, the total height is 200 mm, and the diameter is 150 mm. The four vanes in the device are used to simulate the track teeth in actual working conditions, the vane height is 50 mm, and the diameter is 25 mm. The torsion bar has a diameter of 6 mm and is connected to the motor. The motor drives the torsion bar to rotate, driving the vanes to apply a shearing force to the soil sample, thereby simulating the shearing effect of the track teeth on the deep-sea sediment soil during the driving process of the crawler vehicle. There are 5 pressurizing airbags in the test device, and 4 of them (Airbag 1, Airbag 2, Airbag 3, Airbag 4) are closely attached to the inner wall of the soil sample container, used to simulate the uneven distribution of the grounding pressure caused by the change of the center of gravity during the driving process of the crawler vehicle. The pressure values generated by each airbag in the vertical direction are equal, and their values are respectively denoted as σ 11 , σ 12 , σ 13 , σ 14。The airbag 5 is closely attached to the bottom of the soil sample container and is used to simulate the pressure on the side wall 2 of the track tooth. The pressure value is calculated by the formula where w is the weight of the mining vehicle, b is the width of the crawler, and h is the height of the track tooth. Since the influence of the ground pressure distribution on the side wall effect is relatively small, the change is ignored in this test device and method and is denoted as σ 31 , σ 32 , σ 33 , σ 34 . Small pressure sensors with a diameter of 20 mm are buried in the device and are arranged around and above and below the blade respectively for real-time measurement of the ground pressure and lateral pressure. In addition, a standard sand cushion layer is laid outside the device to simulate the pressure on the side wall 1 of the track tooth, denoted as σ 21 , σ22, σ23, σ24.

[0026] As Figure 1 shown, the dynamic rotary shear test device for evaluating the shear action between the deep-sea mining crawler and the soil includes 1. airbag 1, 2. airbag 2, 3. airbag 3, 4. airbag 4, 5. pressure sensor 1, 6. pressure sensor 2, 7. pressure sensor 3, 8. pressure sensor 4, 9. blade 1, 10. blade 2, 11. blade 3, 12. blade 4, 13. pressure sensor 5, 14. pressure sensor 6, 15. pressure sensor 7, 16. pressure sensor 8, 17. torsion bar, 18. airbag 5, 19. sand cushion layer, 20. device plate.

[0027] Due to the great difficulty in sampling deep-sea soft bottom soil, the present invention uses simulated soil to replace the deep-sea soft bottom soil as the test soil sample. The preparation method of the simulated soil is as follows:

[0028] Select bentonite, and determine its mineral composition, particle size and specific surface area through a diffractometer, a laser diffraction particle size analyzer and a full-automatic specific surface area analyzer to ensure its similarity to the deep-sea soft bottom soil; mix bentonite and water in different proportions and configure simulated soils in different states according to the difference between the liquid limit and the plastic limit. Use the ring knife method, the direct quick shear method and other methods to measure the physical and mechanical parameters of the simulated soil (including wet density, moisture content, liquid limit, plastic limit, cohesion, internal friction angle and penetration resistance, etc.), and compare them with the deep-sea soft bottom soil to ensure a high degree of matching of the physical and chemical properties with the deep-sea soft bottom soil.

[0029] The simulated soil is loaded into the soil sample container by the layered filling method. The specific steps are as follows:

[0030] 1. Place the first ring on the horizontal base and temporarily fix it with flange bolts. Apply a thin layer of vaseline (with a thickness of 1 mm) evenly on the inner wall of the ring to reduce the friction between the soil and the ring wall.

[0031] 2. Pour the rock-like soil into the ring in three times, and statically press it with a hydraulic compactor for 5 minutes each time. After compaction, measure the actual height. If it is less than 50 mm, fill the soil to the marked line. Use a screed to scrape off the excess soil along the ring opening to ensure a flat surface (flatness error ≤ 1 mm). Sprinkle silane water repellent on the compacted surface to simulate the low permeability after the deep-sea soil becomes rock. Use a toothed scraper (tooth depth 2 mm) to draw a mesh groove on the compacted surface to enhance the interlayer bonding.

[0032] 3. When filling the second layer, remove the temporary fixing bolts of the first ring, align the ring 2 with the flange, and pre-tighten the bolts. Check the gap between the rings. If there is a gap, apply Vaseline for sealing.

[0033] 4. Repeat the filling of ring 1, where the plastic soil in ring 2 is compacted with an impact rammer, the fluid plastic soil in ring 3 is compacted with a low-impact rammer, and the flowing soil in ring 4 settles by its own weight.

[0034] Four sidewall airbags (airbag 1, airbag 2, airbag 3, airbag 4) are evenly distributed along the circumferential direction on the inner wall of the soil sample container, and the central angle between adjacent airbags is 90°. Each sidewall airbag is divided into 4 sections, each section is 50 mm high, corresponding to 4 soil sample container rings; each section of the sidewall airbag is provided with a quick interface to ensure the air circuit connection between the upper and lower layers. The bottom airbag (airbag 5) is coaxially installed at the center of the bottom of the soil sample container. The airbag type is selected as rubber material, the inflation medium is air, and a high-pressure gas cylinder is used to inflate the airbag. The airbag is subjected to a airtightness test before inflation, and the surface of the airbag is coated with an anti-sticking coating to avoid adhesion to the soil.

[0035] In the test device for layered filling of soil, to ensure effective contact between the airbag and the soil and achieve uniform pressure increase, the installation of the airbag adopts a phased synchronous installation method, and the specific steps are as follows:

[0036] 1. First, pre-fix the bottom airbag 5. Place the bottom airbag at the center of the container base and temporarily fix it by vacuum adsorption.

[0037] 2. Perform interface treatment on the airbag. Coat a silicon-based friction-increasing coating (friction coefficient μ≥0.7) on the airbag contact surface, and the coating thickness is 0.3±0.05 mm; connect the airbag to the inflation pipe (4 mm inner diameter polyurethane pipe), and the pipeline is led out along the groove at the bottom of the container, and the interface adopts a double-sealing structure.

[0038] 3. Temporarily fix the first section of the sidewall airbag on the inner wall of ring 1 with double-sided tape in advance. At this time, the sidewall airbag is in an uninflated state. A 5 mm flange is reserved at the upper edge of the first section of the airbag for overlapping with the adjacent airbag section. The first section of the airbag is independently connected to the inflation pipe (4 mm inner diameter polyurethane pipe), and the pipeline is led out along the groove on the outer wall of the container, and the interface adopts a double-sealing structure.

[0039] 4. Fill the soil body according to the above steps of layered filling of simulated soil, and compact it to a height of 50 mm. Avoid the position of the airbag during filling to ensure natural contact between the airbag and the side of the soil body.

[0040] 5. Set the ring 2 above the ring 1, align the flange bolt holes, leave a 5-mm flange at the upper and lower edges of the second-stage airbag, and connect the lower flange of the second-stage sidewall airbag to the upper flange of the first-stage airbag through a joint; fill the soil body and compact it. Avoid colliding with the airbag during operation. After filling the soil, check the contact surface between the airbag and the soil body to ensure no voids.

[0041] 6. Repeat the above steps to install the ring 3 and ring 4, install the sidewall airbags layer by layer, and finally conduct a seal check.

[0042] The airbag inflation adopts a staged inflation process, and the specific steps are as follows:

[0043] 1. All airbags are simultaneously inflated to the initial pressure P0 (5 kPa) to eliminate the installation gap and maintain it for 60 s.

[0044] 2. The four sidewall airbags rise to 50% of the design pressure (P d ×50%) at a rate of ΔP1 = 2 kPa / s and maintain the pressure for 120 s.

[0045] 3. Inflate alternately and diagonally, increasing by 10% P d each time, with a step interval of 30 s.

[0046] 4. The bottom airbag is inflated laggingly. When the sidewall pressure reaches 70% of P d ×70%, it linearly increases the pressure to 80% of P d ×80% at a rate of ΔP2 = 1 kPa / s.

[0047] 5. Enter the balance and pressure stabilization stage, and increase the airbag pressure to the design value after the airbag pressure is stable.

[0048] The pressure sensors are buried after the soil sample filling is completed. The specific burial positions are as follows:

[0049] The axes of the pressure sensors (pressure sensor 1, pressure sensor 2, pressure sensor 3, pressure sensor 4) around the blade are parallel to the upper surface of the soil sample container. The midpoint is 75 mm above the soil sample container and 25 mm away from the outer edge of the blade; the axes of the pressure sensors (pressure sensor 5, pressure sensor 6) above the blade are perpendicular to the upper surface of the soil sample container. The center point is 25 mm above the soil sample container, and the center lines are perpendicular to the midpoints of blade 1 and blade 3 respectively; the axes of the pressure sensors (pressure sensor 7, pressure sensor 8) below the blade are perpendicular to the lower surface of the soil sample container. The center point is 75 mm below the soil sample container, and the center lines are perpendicular to the midpoints of blade 1 and blade 3 respectively; the diameter of all pressure sensors is 20 mm and the thickness is 8 mm.

[0050] When the pressure sensors are buried, the specific steps are as follows:

[0051] 1. Mark the sensors according to the numbers (1 - 8), pre - calibrate and record the initial zero value, and ensure that the cable length is sufficient to lead out of the container.

[0052] 2. Locate the specific positions of the above - mentioned pressure sensors (1 - 8) respectively and mark the burial points.

[0053] 3. Use a micro - drill (with a diameter of 30 - 40 mm) to drill holes horizontally around the sensors (1 - 4) on the four sides of the blade at the marked points. The axis of the drill hole is parallel to the surface of the container; push the sensor horizontally into the hole to ensure that its axis is consistent with the drilling direction and the force - receiving surface faces the edge of the blade; the outer surface of the sensor is flush with the hole opening to avoid protrusion or depression.

[0054] 4. Use a drill with a diameter of 30 mm to drill vertically downward with a drilling depth of 29 mm and a hole diameter of 30 - 40 mm; place the pressure sensors (5 - 6) vertically in the hole with the center point coinciding with the marked point.

[0055] 5. Drill a hole upward from the lower surface of the container (leave an operation opening at the bottom of the container) with a drilling depth of 79 mm and a hole diameter of 30 - 40 mm; push the sensor vertically into the hole with the center point 75 mm away from the lower surface, the axis perpendicular to the bottom surface of the container, and the force - receiving surface facing upward the blade.

[0056] 6. When backfilling, the material used is simulated soil that matches the properties of the soil sample to ensure consistent stress transfer; all the sensor cables are led out along the container wall or the reserved channel, and are sheathed with a flexible hose to prevent abrasion and avoid cross - interference.

[0057] The pressure exerted by the four side - wall airbags installed on the inner wall of the soil - sample container is used to simulate the ground pressure received by the track teeth in the actual working condition. Due to the existence of lateral and longitudinal eccentricity when the mining vehicle is moving, the offset of its center of gravity causes the ground pressure to be unevenly distributed in the track length direction. In the test device, the 4 side - wall airbags respectively correspond to the ground pressure values σ 11 、σ 12 、σ 13 、σ 14 (see Figure 6 ), and non - uniform pressure loading is achieved by independently controlling the pressure values of each airbag. Taking blade 1 (track tooth 1) as an example, its corresponding pressure value is σ 11 (see Figure 5 ).

[0058] The pressure exerted by the airbag 5 installed at the bottom of the soil sample container is used to simulate the lateral pressure on the side of the track tooth. In actual working conditions, the unevenness of the ground pressure distribution has little effect on the sidewall effect of the track tooth, and the calculation complexity of the lateral pressure under non-uniform pressure is relatively high. Therefore, in this test device, the influence of only the weight (w) of the mining vehicle, the track width (b), and the track tooth height (h) is considered for the lateral pressure, and the calculation formula is The lateral pressure values σ 21 、σ 22 、σ 23 、σ 24 and σ 31 、σ 32 、σ 33 、σ 34 on both sides of the track tooth in actual working conditions are obtained Figure 7 、 Figure 8 . Taking blade 1 (track tooth 1) as an example, the corresponding values are σ 21 and σ 31 (see Figure 5 ).

[0059] In this test device, a sand cushion surcharge is used to simulate the lateral pressure σ 21 、σ 22 、σ 23 、σ 24 . The sand gradation is selected as uniform medium sand with a particle size of 0.1 - 2 mm, and the coefficient of uniformity C u <5. The moisture content of the sand and soil is adjusted to 5% - 8% by drying or spraying water to avoid liquefaction or looseness. The sand cushion surcharge adopts a layered surcharge process, with each layer laid with a thickness of 10 - 15 cm to prevent uneven compaction due to excessive thickness. In the middle area, a light vibrating plate is used for compaction (vibrating force 2 - 5 kN, frequency 30 - 50 Hz), and in the corner area, manual ramming is used (drop hammer height ≤ 30 cm); after each layer is compacted, the dry density is measured by the core cutter method to ensure that the degree of compaction ≥ 95%.

[0060] This test device simulates the shear rate of the track tooth corresponding to different driving speeds of the mining vehicle by adjusting the angular velocity (ω) of the motor-driven torsion bar. Blades with diameters of 25 mm, 28 mm, and 30 mm are designed to study the influence of the track tooth height on the shear effect; parabolic, triangular, trapezoidal and other blade shapes are adopted (see Figure 9 ) to analyze the shear performance differences of different track tooth shapes.

[0061] The test method of the dynamic rotary shear test device for evaluating the track-soil shear action of the deep-sea mining tracked vehicle is as follows:

[0062] 1. Prepare simulated soil samples in different states by mixing bentonite and water in a certain proportion, layer the simulated soil samples into the soil sample container, and at the same time embed the segmented airbag at the set position;

[0063] 2. The hydraulic servo system is adopted to drive the blade shearing device to penetrate the soil sample at a uniform speed of 0.5 - 1.2 mm / s until the critical distance of 100 ± 2 mm from the bottom of the container is maintained; the pressure sensor is buried at the set position by the drilling method, and graded sand and gravel are laid on the surface of the test plate to form a load transfer layer with a thickness of 30 - 50 mm;

[0064] 3. The segmented airbag is subjected to gradient pressure increase through an independent gas path control system, and pressure closed-loop control is achieved based on the feedback data of the pressure sensor, so that the internal stress field of the soil reaches the designed distribution state;

[0065] 4. Start the variable-frequency motor, drive the shearing device to run at an initial speed of 0.5 - 2 r / min, continuously collect torque-time series data through the dynamic torque sensor, synchronously record the real-time parameters of the blade angular velocity ω = 2πn and the displacement field distribution on the soil surface until the torque fluctuation amplitude ≤ 5% is determined as the stable state; gradually increase the speed to the medium-speed section (3 - 8 r / min) at a gradient of 10 - 15%, and focus on monitoring the crack evolution characteristics on the soil surface at the torque peak; after entering the high-speed shearing stage (≥ 10 r / min), record the dynamic response data in real time, and monitor phenomena such as sudden torque drop and abnormal fluctuation of the pressure sensor;

[0066] 5. On the basis of the above tests, change the blade geometric parameters, repeat the above experimental steps and record the test data;

[0067] 6. Based on the recorded test data, calculate the dynamic shear strength based on the torque extreme value M, Combined with the shear strain rate Establish dimensional relationship curves, including: torque - speed curve, shear strength - strain rate curve, three-dimensional stress field distribution cloud map, shear band morphology - rate relationship curve, speed - shear strength curve, tooth height - shear strength curve, and tooth shape - shear strength curve, etc.

Claims

1. A dynamic rotary shear test device and method for evaluating the shearing effect of crawler-soil of deep-sea mining crawler vehicles. The test device mainly includes a four-state environmental control system, a soil stress simulation system, a soil loading system, a dynamic rotary shear test system for grousers, and a data acquisition system. The four-state environmental control system consists of simulated soil and annular structures in four different states, simulating the surface characteristics of deep-sea soft soil transitioning from a flow state to a plastic state as the depth increases; the soil stress simulation system consists of four side wall airbags, a bottom center airbag, and a top sand cushion layer, accurately reproducing the stress state of the grouser in the deep-sea environment; the soil loading system consists of a top sand cushion layer, four side wall airbags, a bottom center airbag, and a high-pressure gas cylinder, simulating different buried deep-sea soil environments; the dynamic rotary shear test system for grousers consists of blades, torsion bars, and variable frequency motors, simulating the effects of multiple types of grousers on the shear strength of deep-sea soil; the data acquisition system consists of pressure sensors and dynamic torque sensors. Based on the test device, a multi-step test method is used to accurately simulate the shear failure process of multiple types of grousers on soil under different deep-sea working conditions.

2. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: The four-state environmental control system consists of four 50mm high annular structures stacked together, with a total height of 200mm and a diameter of 150mm. The four annular structures are filled with deep-sea soft soil in flow state, flow-plastic state, plastic state and rock state from top to bottom, respectively, simulating the surface characteristics of deep-sea soft soil transitioning from flow state to plastic state with increasing depth.

3. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: In the soil stress simulation system, four side wall airbags are evenly distributed on the inner wall of the cylindrical soil sample container along the circumferential direction. The center angle of adjacent airbags is 90°. Each side wall airbag is divided into four sections along the height direction. Each section corresponds to a single-layer annular structure. The applied pressure is used to simulate the ground pressure σ of the grouser in actual working conditions. 11 , σ 12 , σ 13 , σ 14 The bottom airbag is coaxially installed at the center of the bottom of the soil sample container, and the pressure applied is used to simulate the lateral pressure σ on the side wall 2 of the grouser in actual working conditions 31 , σ 32 , σ 33 , σ 34 The airbags are installed in stages and synchronously. The bottom airbag is temporarily fixed by vacuum adsorption, and the side wall airbags are temporarily fixed in advance with double-sided tape. Each side wall airbag is equipped with a quick interface to ensure that the air path between the upper and lower layers is connected. The surface of the airbag is coated with an anti-stick coating to avoid adhesion with the soil. A sand cushion layer is laid on the top of the test plate to simulate the lateral pressure σ on the side wall 1 of the grouser in actual working conditions. 21 , σ 22 , σ 23 , σ 24 .

4. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: The airbag type in the soil loading system is made of rubber material, the inflation medium is air, and the airbag is inflated by a high-pressure gas cylinder; the sand cushion layer adopts a layered loading process, the compaction degree is ≥95%, and the laying thickness of each layer is 10-15cm. The middle area is compacted by a vibration plate with an exciting force of 2-5kN and a frequency of 30-50Hz, and the corner area is compacted manually with a drop hammer height of ≤30cm; by controlling different target values ​​when the airbag is inflated and changing the laying thickness and compaction degree of the sand cushion layer, different deep sea soil environments are simulated.

5. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: The torsion bar diameter in the dynamic rotary shear test system of the grouser is 6mm, which is connected to the variable frequency motor and driven to rotate by the motor; the four blades are 50mm high and 25mm in diameter, which are used to simulate the shearing effect of the grouser on the soil; the stress σ 11 , σ 21 , σ 31 They correspond to the stresses on the grouser when the mining vehicle is moving in actual working conditions; the blade diameter can be replaced with 25mm, 28mm or 30mm, and the shape can be replaced with parabola, triangle or trapezoid. The shear rate is changed and controlled by a variable frequency motor to simulate the influence of multiple types of grousers and shear rates on the shear strength of deep-sea soft soil.

6. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: The pressure sensors in the data acquisition system are 20mm in diameter and 8mm thick; the axis of the pressure sensors around the blades is parallel to the upper surface of the soil sample container, the center point is 75mm above the soil sample container and 25mm from the outer edge of the blade; the axis of the pressure sensor above the blade is perpendicular to the upper surface of the soil sample container, the center point is 25mm above the soil sample container, and the center line is perpendicular to the midpoints of blade 1 and blade 3 respectively; the axis of the pressure sensor below the blade is perpendicular to the lower surface of the soil sample container, the center point is 75mm below the soil sample container, and the center line is perpendicular to the midpoints of blade 1 and blade 3 respectively; after the soil sample is filled, a micro-drilling machine is used to drill holes at the designed position of the soil sample container and bury it. All sensor cables are led out along the container wall or reserved grooves, and the outer jacket hose prevents wear and avoids cross interference.

7. The dynamic rotary shear test device for evaluating the shear effect of deep-sea mining crawler vehicles on soil according to claim 1, characterized in that: The test method of the dynamic rotary shear test device based on the evaluation of the deep-sea mining crawler-soil shearing effect is as follows:

1. Prepare simulated soil samples in different states by mixing bentonite and water in a certain proportion, and load the simulated soil samples into the soil sample container in layers, while pre-burying the segmented airbags at the set positions; 2. Use the hydraulic servo system to drive the blade shearing device to penetrate the soil sample at a uniform speed of 0.5-1.2mm / s until it maintains a critical distance of 100±2mm from the bottom of the container; use the drilling method to bury the pressure sensor at the set position, and lay graded sand and gravel on the surface of the test plate to form a load transfer layer with a thickness of 30-50mm; 3. Gradual pressurization is implemented on the segmented airbags through an independent air circuit control system, and pressure closed-loop control is achieved based on the feedback data from the pressure sensor, so that the stress field inside the soil reaches the designed distribution state; 4. Start the variable frequency motor and drive the shearing device to run at an initial speed of 0.5-2r / min. Use the dynamic torque sensor to continuously collect torque-time series data, and synchronously record the real-time parameters of the blade angular velocity ω=2πn and the displacement field distribution on the soil surface until the torque fluctuation amplitude is ≤5% and it is determined to be a stable state; gradually increase the speed to the medium speed section (3-8r / min) at a gradient of 10-15%, focusing on monitoring the crack evolution characteristics on the soil surface at the torque peak; After entering the high-speed shear stage (≥10r / min), the dynamic response data is recorded in real time, and phenomena such as torque drop and abnormal fluctuation of pressure sensor are monitored; 5. Based on the above test, change the blade geometric parameters, repeat the above experimental steps and record the test data; 6. According to the recorded test data, the dynamic shear strength is calculated based on the torque extreme value M. Combined shear strain rate Establish dimensional relationship curves, including: torque-speed curve, shear strength-strain rate curve, three-dimensional stress field distribution cloud map, shear band morphology-rate relationship curve, speed-shear strength curve, grouser height-shear strength curve and grouser shape-shear strength curve, etc.

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