A device for preparing a coarse-grained undisturbed soil triaxial specimen

Abstract

The utility model relates to coarse granular undisturbed soil triaxial sample preparation technical field, concretely relates to a kind of coarse granular undisturbed soil triaxial sample preparation devices of preventing particle peeling, including frame, propulsion mechanism, cutting mechanism and negative pressure film covering component, frame includes base, top plate is arranged in parallel in base directly above, multiple linear guide posts are equipped between base and top plate;The coarse granular undisturbed soil triaxial sample preparation device adopts double-wall decoupling cutting and negative pressure in situ film covering structure, outer sleeve high-speed grinding cuts off hard coarse grain, avoids particle peeling and soil skeleton disturbance;Inner layer stationary constraint protection cylinder pre-isolation core soil sample, guarantee sample size accuracy;Negative pressure film covering adsorbs latex film in advance, shaping is coated, eliminate surface gap, prevent film breakage and stress unevenness;Automatic cutting greatly improves efficiency, effective inhibition stress release, lateral expansion and moisture loss throughout lateral restraint, realize coarse granular undisturbed soil low disturbance, high accuracy, high fidelity sample preparation, satisfy triaxial test requirement.

Description

Technical Field

[0001] This utility model relates to the field of triaxial sample preparation technology for coarse-grained undisturbed soil, specifically to a device for preparing triaxial samples of coarse-grained undisturbed soil that prevents particle shedding. Background Technology

[0002] In the fields of geotechnical engineering investigation and laboratory soil mechanics testing, triaxial compression testing is the core method for determining the shear strength parameters, deformation modulus, and pore water pressure dissipation characteristics of natural soil. To ensure that the test results can truly reflect the mechanical response of the in-situ strata, the specifications require the use of undisturbed soil samples that retain their natural structure and initial moisture content, and to process them into standard cylindrical specimens for testing.

[0003] Currently, the preparation of undisturbed triaxial soil samples is mostly done manually or semi-manually, typically using a fine wire saw or soil cutter to shape the sample in a cutting pan or split-type circular mold. However, existing methods have significant drawbacks when preparing coarse-grained undisturbed soil samples such as glacial till, loess containing calcareous nodules, and marine sediments containing shells.

[0004] Firstly, the cutting blade applies static compression and shear tearing action, while the wire saw relies on reciprocating friction cutting. Neither of them can effectively cut hard coarse particles. Forced cutting easily causes the boundary particles to be unbalanced in force. After the interfacial bonding force is broken, the whole particle peels off, causing holes and dimensional deviations on the sample surface. At the same time, it tears the soil skeleton and induces internal microcracks, so that the triaxial test cannot accurately reflect the true peak shear strength of the soil.

[0005] Secondly, the flaking of particles creates pitted surfaces, which can easily lead to irregular gaps after the latex film is applied. When confining pressure is applied, the fluid pushes the film into the pits, which can easily cause the film to tensile and break, leak water, and form a non-uniform additional stress field at the boundary of the sample, which violates the basic assumption of uniform boundary stress in triaxial tests.

[0006] Third, manual cutting is inefficient and time-consuming, and the side of the sample is exposed without lateral confinement for a long time, which leads to the rapid release of effective stress in the soil, lateral expansion and water loss, further reducing the reliability of the test.

[0007] In summary, existing sample preparation methods suffer from low automation, high risk of particle stripping, and significant soil disturbance, making it difficult to meet the requirements for low-disturbance and high-precision sample preparation of coarse-grained undisturbed soil. There is an urgent need for an automated, low-disturbance, particle-stripping-proof triaxial sample preparation device for coarse-grained undisturbed soil. Utility Model Content

[0008] To achieve the above objectives, this utility model adopts the following technical solution: This utility model provides a triaxial sample preparation device for coarse-grained undisturbed soil with anti-particle-stripping properties. It employs a double-walled decoupled cutting and negative pressure in-situ membrane structure. The outer sleeve uses high-speed grinding to cut hard coarse particles, preventing particle stripping and disturbance of the soil skeleton. The inner static constraint sleeve pre-isolates the core soil sample, ensuring sample dimensional accuracy. The negative pressure membrane pre-absorbs latex film, forming and covering the sample, eliminating surface voids and preventing film damage and stress unevenness. Automated cutting significantly improves efficiency, and lateral constraint throughout the process effectively suppresses stress release, lateral expansion, and moisture loss, achieving low-disturbance, high-precision, and high-fidelity sample preparation of coarse-grained undisturbed soil, meeting the requirements of triaxial testing.

[0009] To address the problems of existing technologies, this utility model provides a triaxial sample preparation device for coarse-grained undisturbed soil with anti-particle-shedding properties, comprising a frame, a propulsion mechanism, a cutting mechanism, and a negative pressure membrane assembly. The frame includes a base, with a top plate arranged parallel to the base. Multiple linear guide columns are fixed between the base and the top plate, and a lifting beam that can slide along its axis is sleeved on the outer side of the multiple linear guide columns. The propulsion mechanism is installed on the top of the top plate, and the driving end of the propulsion mechanism vertically penetrates the top plate and is fixedly connected to the top of the lifting beam. The cutting mechanism is vertically centered at the bottom of the lifting beam and is used to descend and cut the shaped soil sample under the drive of the propulsion mechanism. The cutting mechanism includes a coaxial... The system comprises a nested outer rotary cutting power sleeve and an inner static constraint sleeve. The outer rotary cutting power sleeve has equally spaced, annularly distributed cutting teeth at its bottom end. The inner static constraint sleeve has an anti-rotation component at its top, which is vertically slidably connected to a lifting beam. The inner static constraint sleeve is circumferentially decoupled from the inner cavity of the outer rotary cutting power sleeve via bearings and achieves axial floating through the vertical sliding cooperation between the anti-rotation component and the lifting beam. A motor drive assembly is installed at the top of the lifting beam, and its output end is connected to the outer rotary cutting power sleeve. A negative pressure film-coating assembly is integrated into the inner static constraint sleeve and is used to coat the cut and shaped soil sample.

[0010] Preferably, a sample fixing and centering gimbal is installed at the center of the top of the base to anchor the undisturbed soil sample to be cut; the inner static constraint casing is kept circumferentially static with the lifting beam through the anti-rotation component, and the bottom end of the inner static constraint casing is provided with an inner chamfered static cutting edge.

[0011] Preferably, the inner chamfered stationary cutting edge protrudes downwards from the working surface of the cutting tooth at the bottom end of the outer rotary cutting power sleeve in vertical height, with a downward protrusion difference of 0.5mm to 1.0mm.

[0012] Preferably, the outer cylindrical surface of the outer rotary cutting power sleeve is provided with a spiral chip removal groove; the cutting teeth are formed by alternating diamond composite sheets and cemented carbide wear-resistant blocks.

[0013] Preferably, it also includes a chip removal system; the chip removal system includes an annular dust collection hood sleeved outside the outer rotary cutting power sleeve, and the annular dust collection hood is connected to an external negative pressure suction chip removal pipe.

[0014] Preferably, the inner static constraint sleeve has a hollow negative pressure interlayer air chamber inside, and the inner sidewall of the inner static constraint sleeve has micropores that connect the hollow negative pressure interlayer air chamber to the inner cavity of the sleeve; the hollow negative pressure interlayer air chamber is connected to an external negative pressure source through a connecting pipe, and is used to adsorb the latex film onto the inner sidewall of the inner static constraint sleeve through negative pressure; the hollow negative pressure interlayer air chamber, micropores, connecting pipe, and external negative pressure source together constitute the negative pressure sleeve assembly.

[0015] Preferably, a deep groove ball ceramic bearing is provided in the gap between the inner static constraint sleeve and the outer rotary cutting power sleeve; the anti-rotation component includes an anti-rotation guide rod, one end of which is connected to the inner static constraint sleeve, and the other end is inserted through the lifting beam; the lifting beam is vertically provided with a vertical limiting hole for the anti-rotation guide rod to slide vertically.

[0016] Preferably, a mechanical sensor is installed in series at the force-bearing node connecting the propulsion mechanism and the lifting beam; the mechanical sensor is used to detect the cutting reaction force of the sample and is connected in communication with the controller to adaptively adjust the propulsion speed of the propulsion mechanism.

[0017] The advantages of this utility model compared to the prior art are:

[0018] 1. A double-wall structure is adopted, with an outer rotary cutting power sleeve for high-speed grinding and an inner static constraint sleeve for pre-isolation. High-frequency micro-grinding replaces static shearing to smoothly cut hard coarse particles. At the same time, the inner static constraint sleeve defines the sample boundary in advance to ensure dimensional accuracy and strength test accuracy.

[0019] 2. By integrating a negative pressure membrane assembly with an inner static constraint sleeve, the latex film is pre-adsorbed onto the inner wall before cutting, and the formed soil sample is immediately covered to eliminate pits and voids.

[0020] 3. Servo propulsion and spindle drive enable fully automatic cutting, significantly shortening sample preparation time. During the molding process, the soil sample is continuously subjected to lateral constraint and film sealing, which inhibits stress release, lateral expansion and moisture loss, significantly improving sample fidelity and test reliability. Attached Figure Description

[0021] Figure 1 This is a front-view three-dimensional structural schematic diagram of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0022] Figure 2This is a rear-view three-dimensional structural diagram of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0023] Figure 3 This is a schematic diagram of the front view three-dimensional cross-section of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0024] Figure 4 yes Figure 3 A magnified structural diagram at point A.

[0025] Figure 5 This is a schematic diagram of the front view of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0026] Figure 6 yes Figure 5 A magnified structural diagram at point B.

[0027] Figure 7 This is a three-dimensional schematic diagram of the cutting mechanism of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0028] Figure 8 This is a three-dimensional disassembled schematic diagram of the cutting mechanism of a triaxial sample preparation device for coarse-grained undisturbed soil that prevents particle stripping.

[0029] The diagram is labeled as follows: 1. Frame; 1a. Base; 1b. Top plate; 1c. Linear guide column; 1d. Lifting beam; 1d1. Motor drive assembly; 2. Propulsion mechanism; 3. Cutting mechanism; 3a. Outer rotary cutting power sleeve; 3a1. Cutting teeth; 3a2. Deep groove ball ceramic bearing; 3b. Inner static constraint sleeve; 3b1. Inner chamfered static cutting edge; 3b2. Hollow negative pressure interlayer air chamber; 3b3. Anti-rotation guide rod; 4. Negative pressure membrane assembly; 5. Sample fixing and self-aligning gimbal; 6. Chip removal system; 6a. Annular dust collection hood; 6a1. External negative pressure suction chip removal pipe; 7. Mechanical sensor. Detailed Implementation

[0030] To further understand the features, technical means, and specific objectives and functions achieved by this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments.

[0031] See Figures 1 to 8 As shown, a triaxial sample preparation device for coarse-grained undisturbed soil with anti-particle stripping includes a frame 1, a propulsion mechanism 2, a cutting mechanism 3, and a negative pressure membrane assembly 4.

[0032] The frame 1 includes a base 1a, a top plate 1b is arranged parallel to the top of the base 1a, and multiple linear guide posts 1c are fixed between the base 1a and the top plate 1b. A lifting beam 1d that can slide along its axis is sleeved on the outside of the multiple linear guide posts 1c.

[0033] The aforementioned base 1a is used to support the entire machine and soil sample, the top plate 1b is used to install the drive components, the linear guide column 1c ensures that the lifting beam 1d moves smoothly, and the lifting beam 1d is used to install the cutting mechanism 3 and drive its lifting.

[0034] See Figure 1 , Figure 3 and Figure 5 As shown, the propulsion mechanism 2 is installed on the top of the top plate 1b, and the driving end of the propulsion mechanism 2 extends vertically through the top plate 1b and is fixedly connected to the top of the lifting beam 1d.

[0035] Among them, the propulsion mechanism 2 provides vertical power to realize the lifting and feeding of the cutting mechanism 3. The drive end is fixedly connected to the lifting beam 1d to ensure stable power transmission.

[0036] See Figures 1 to 3 and Figure 5 As shown, the cutting mechanism 3 is vertically centered at the bottom of the lifting beam 1d, and is used to descend and cut the shaped soil sample under the drive of the propulsion mechanism 2.

[0037] The aforementioned cutting mechanism 3 is the core processing component. Its central installation ensures that the cutting center is aligned with the soil sample center, thereby improving the coaxiality of the sample preparation.

[0038] See Figure 2 , Figure 3 , Figure 5 and Figure 7 As shown, the cutting mechanism 3 includes an outer rotary cutting power sleeve 3a and an inner static constraint sleeve 3b, which are coaxially nested.

[0039] The outer rotary cutting power sleeve 3a has cutting teeth 3a1 arranged in a ring at equal intervals at its bottom end.

[0040] The inner static constraint sleeve 3b is provided with an anti-rotation component at its top. The anti-rotation component is vertically slidably connected to the lifting beam 1d. The inner static constraint sleeve 3b is circumferentially decoupled from the inner cavity of the outer rotary cutting power sleeve 3a by a bearing, and axial floating is achieved through the vertical sliding cooperation between the anti-rotation component and the lifting beam 1d.

[0041] The outer rotary cutting power sleeve 3a has an extension plate protruding from its top. The bottom of the lifting beam 1d is bolted with a clamping seat for rotating and holding the extension plate. The outer rotary cutting power sleeve 3a is rotatably mounted on the bottom of the lifting beam 1d with the clamping seat via bolts.

[0042] The cutting mechanism 3 adopts a decoupled arrangement of inner and outer double walls. During operation, the outer rotary cutting power sleeve 3a rotates and cuts through the bottom cutting teeth 3a1, while the inner static constraint sleeve 3b remains fixed and stationary. The inner chamfered static cutting edge 3b1 protects the core soil sample, significantly reducing soil shear disturbance caused by torque during rotary cutting and effectively preserving the original soil sample structure. The inner static constraint sleeve 3b is suspended inside the outer rotary cutting power sleeve 3a by a deep groove ball ceramic bearing 3a2. There is no rigid connection between the two, achieving circumferential rotational decoupling. The deep groove ball ceramic bearing 3a2 adopts a bidirectional axial limiting structure. The inner ring of the bearing is positioned by the sleeve shoulder and locking retainer ring, while the outer ring is limited by the sleeve bearing seat step and fastening end cap. This effectively restricts axial movement, retaining only circumferential rotational capability, ensuring the independent working state of the outer sleeve's rotary cutting and the inner static constraint sleeve 3b's static protection, avoiding motion interference. Meanwhile, the anti-rotation guide rod 3b3 of the inner static constraint casing 3b, together with the linear guide column 1c and the lifting beam 1d of the frame 1, forms a vertical sliding structure, which completes the overall vertical lifting under the drive of the propulsion mechanism 2. The bearing as a whole does not have a rigid locking structure, and can adaptively float axially with drilling, cutting, and retraction processes to compensate for operational displacement deviations, buffer axial impact loads, and prevent bearing damage under pressure. It works in conjunction with the frame 1 and the propulsion mechanism 2 to ensure the stable operation of soil sampling.

[0043] The circularly arranged cutting teeth 3a1 achieve uniform and continuous cutting, avoiding local stress concentration.

[0044] High-speed grinding generates low tangential force, which can smoothly cut hard, large soil particles, eliminate problems such as sidewall holes and skeleton tearing in soil samples, and significantly reduce sample size tolerance.

[0045] See Figure 2 and Figure 7 As shown, a motor drive assembly 1d1 is installed on the top of the lifting beam 1d, and the output end of the motor drive assembly 1d1 is connected to the outer rotary cutting power sleeve 3a.

[0046] It should be noted that the motor drive component 1d1 provides rotational power, which drives the outer rotary cutting power sleeve 3a to rotate at high speed, realizing the grinding operation of the cutting teeth 3a1, achieving the effect of high-frequency rotation combined with micro-cutting depth, and greatly reducing the shear disturbance to the soil.

[0047] See Figure 3 , Figure 5 and Figure 7 As shown, the negative pressure membrane assembly 4 is integrated into the inner static constraint sleeve 3b and is used to cover the soil sample after cutting and shaping.

[0048] The negative pressure membrane assembly 4 and the inner static constraint casing 3b are integrated into one design, and the cutting and membrane installation are carried out simultaneously to reduce the soil sample exposure time.

[0049] The integrated negative pressure-assisted in-situ membrane technology preserves the initial stress and moisture state of the soil, preventing stress relaxation, lateral expansion, and moisture loss caused by long-term unconfined exposure of soil samples.

[0050] See Figure 1 , Figure 3 and Figure 5 As shown, a sample fixing and self-aligning gimbal 5 is installed at the center of the top of the base 1a to anchor the undisturbed soil sample to be cut.

[0051] The soil sample is securely clamped by the sample fixing and centering gimbal 5 to prevent displacement during cutting and ensure that the center of the soil sample is aligned with the center of the cutting mechanism 3.

[0052] Stable clamping reduces vibration disturbance, providing a foundation for low-disturbance cutting.

[0053] See Figures 3 to 7 As shown, the inner static constraint sleeve 3b is circumferentially statically connected to the lifting beam 1d through the anti-rotation component, and the bottom end of the inner static constraint sleeve 3b is provided with an inner chamfered static cutting edge 3b1.

[0054] When in use, the anti-rotation component makes the inner static constraint sleeve 3b and the lifting beam 1d rise and fall synchronously without rotation, and the inner chamfered static cutting edge 3b1 is used to pre-cut into the soil to define the sample boundary.

[0055] During the feed descent, the inner chamfered stationary cutting edge 3b1 first cuts into the soil along the theoretical cylindrical boundary with a minimal displacement volume, physically isolating the core undisturbed soil. The outer cutting teeth 3a1 then cut the outer soil and large particles, maintaining the physical and mechanical properties of the undisturbed soil.

[0056] See Figure 4 and Figure 6 As shown, the inner chamfered stationary cutting edge 3b1 protrudes downwards from the working surface of the cutting tooth 3a1 at the bottom of the outer rotary cutting power sleeve 3a in vertical height, with a downward protrusion difference of 0.5mm to 1.0mm.

[0057] During operation, the cutting edge should be inserted into the soil in advance to isolate the core soil sample and define the cylindrical boundary to avoid disturbing the internal soil with the outer cutting teeth 3a1 and reduce particle shedding.

[0058] See Figure 3 , Figure 6 and Figure 8 As shown, the outer cylindrical surface of the outer rotary cutting power sleeve 3a is provided with a spiral chip removal groove.

[0059] The cutting teeth 3a1 are formed by alternating diamond composite sheets and cemented carbide wear-resistant blocks.

[0060] During operation, the spiral chip removal groove facilitates the removal of cutting chips, and the diamond and cemented carbide materials enhance the hardness and wear resistance of the cutting teeth 3a1, making it suitable for cutting coarse-grained soil.

[0061] The spiral chip removal trough, combined with negative pressure suction, achieves air-cooled pneumatic chip removal, preventing external fluids from entering the soil and maintaining the initial moisture content and matrix suction.

[0062] See Figure 1 , Figures 3 to 8 As shown, the coarse-grained undisturbed soil triaxial sample preparation device also includes a chip removal system 6.

[0063] The chip removal system 6 includes an annular dust collection hood 6a sleeved outside the outer rotary cutting power sleeve 3a, and the annular dust collection hood 6a is connected to an external negative pressure suction chip removal pipe 6a1.

[0064] It should be noted that the chip removal system 6 uses negative pressure suction to promptly remove cutting chips, keeping the cutting area clean and preventing chips from affecting the surface quality of the sample.

[0065] The pure pneumatic discharge scheme, which combines negative pressure suction with a spiral chip removal trough, can remove frictional heat and prevent unsaturated soil from absorbing water and softening, and saline soil from dissolving salt.

[0066] See Figures 3 to 6 As shown, the inner static constraint sleeve 3b has a hollow negative pressure interlayer air chamber 3b2 inside, and the inner sidewall of the inner static constraint sleeve 3b has micropores that connect the hollow negative pressure interlayer air chamber 3b2 with the inner cavity of the sleeve.

[0067] The hollow negative pressure interlayer air chamber 3b2 is connected to an external negative pressure source through a connecting pipe, and is used to adsorb the latex film onto the inner wall of the inner static constraint sleeve 3b through negative pressure.

[0068] The hollow negative pressure interlayer air chamber 3b2, micropores, connecting pipes, and external negative pressure source together constitute the negative pressure membrane assembly 4.

[0069] The above structure utilizes microporous negative pressure technology to pre-absorb and expand the latex film onto the inner wall of the casing. When the soil sample slides in, it is immediately surrounded by the film. After the negative pressure is released, the film elastically retracts and fits evenly, providing lateral stress compensation and improving the sample preparation qualification rate of highly sensitive soil samples.

[0070] See Figures 3 to 6 and Figure 8 As shown, a deep groove ball ceramic bearing 3a2 is provided in the gap between the inner static constraint sleeve 3b and the outer rotary cutting power sleeve 3a.

[0071] The anti-rotation component includes an anti-rotation guide rod 3b3, one end of which is connected to the inner static constraint sleeve 3b, and the other end is inserted through the lifting beam 1d.

[0072] The lifting beam 1d is vertically provided with a vertical limiting hole for the anti-slip guide rod 3b3.

[0073] During operation, the deep groove ball ceramic bearing 3a2 reduces friction between the inner and outer sleeves, and the anti-rotation guide rod 3b3 restricts the rotation of the inner static constraint sleeve 3b, shields the transmission of rotational torque, and ensures that the inner static constraint sleeve 3b remains stationary.

[0074] See Figure 1 , Figure 3 and Figure 5 As shown, a mechanical sensor 7 is installed in series at the force-bearing node connecting the propulsion mechanism 2 and the lifting beam 1d.

[0075] The mechanical sensor 7 is used to detect the cutting reaction force of the sample and is connected to the controller to adaptively adjust the propulsion speed of the propulsion mechanism 2, wherein the controller is a programmable logic controller or a microcontroller.

[0076] It should be added that the propulsion mechanism 2 can be a propulsion cylinder.

[0077] Alternatively, the propulsion mechanism comprises a servo motor, a reducer, a ball screw, and a screw connecting sleeve. In this structure, the servo motor is mounted on the top of the top plate 1b, and its output end is connected to one end of the ball screw via the reducer. The outer side of the ball screw is connected to the screw connecting sleeve, and the bottom of the screw connecting sleeve is connected to the lifting beam 1d. The aforementioned servo motor, reducer, and ball screw constitute a conventional high-precision feed transmission chain in the art, facilitating the realization of micro-feed and closed-loop force feedback control.

[0078] In use, the output of the servo motor is reduced in speed by the reducer and drives the ball screw to rotate. The ball screw and the screw connecting sleeve are threaded together, and then the lifting beam 1d moves down under the guidance of the linear guide column 1c.

[0079] A mechanical sensor 7 is installed in series at the force-bearing node connecting the ball screw and the lifting beam 1d.

[0080] The mechanical sensor 7 is used to detect the cutting reaction force of the sample and feed it back to the controller to adjust the propulsion speed to adapt to soils of different hardness.

[0081] Relying on a high-precision dynamic mechanical sensor 7 and a controller to form a closed-loop feedback system, the system senses changes in soil hardness. When encountering hard particles, it automatically reduces the feed speed and enters a fine grinding mode. After the obstacle is removed, the speed is restored, thus achieving adaptive closed-loop control and improving the standardization and high reproducibility of sample preparation.

[0082] The above embodiments only illustrate one or more implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

Claims

1. A device for preparing triaxial samples of coarse-grained undisturbed soil to prevent particle stripping, characterized in that, It includes a frame (1), a propulsion mechanism (2), a cutting mechanism (3), and a negative pressure membrane assembly (4). The frame (1) includes a base (1a), a top plate (1b) is arranged parallel to the top of the base (1a), and multiple linear guide posts (1c) are fixed between the base (1a) and the top plate (1b). A lifting beam (1d) that can slide along its axis is sleeved on the outside of the multiple linear guide posts (1c). The propulsion mechanism (2) is installed on the top of the top plate (1b), and the driving end of the propulsion mechanism (2) penetrates vertically through the top plate (1b) and is fixedly connected to the top of the lifting beam (1d); The cutting mechanism (3) is vertically and centrally installed at the bottom of the lifting beam (1d) and is used to descend and cut the shaped soil sample under the drive of the propulsion mechanism (2). The cutting mechanism (3) includes an outer layer rotary cutting power sleeve (3a) and an inner layer static constraint sleeve (3b) nested on the same axis. The bottom end of the outer layer rotary cutting power sleeve (3a) is provided with cutting teeth (3a1) arranged in a ring at equal intervals. The top of the inner layer static constraint sleeve (3b) is provided with an anti-rotation component. The anti-rotation component is vertically slidably connected to the lifting beam (1d). The inner layer static constraint sleeve (3b) is circumferentially decoupled from the inner cavity of the outer layer rotary cutting power sleeve (3a) by a bearing and achieves axial floating by vertical sliding cooperation with the lifting beam (1d) through the anti-rotation component. The top of the lifting beam (1d) is equipped with a motor drive component (1d1). The output end of the motor drive component (1d1) is connected to the outer layer rotary cutting power sleeve (3a) through transmission. The negative pressure membrane assembly (4) is integrated into the inner static constraint sleeve (3b) and is used to cover the soil sample after cutting and shaping.

2. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 1, characterized in that, The base (1a) is centrally mounted with a sample fixing and centering gimbal (5) for anchoring the undisturbed soil sample to be cut. The inner static constraint sleeve (3b) is kept circumferentially static with the lifting beam (1d) by the anti-rotation component, and the bottom end of the inner static constraint sleeve (3b) is provided with an inner chamfered static cutting edge (3b1).

3. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 2, characterized in that, The inner chamfered stationary cutting edge (3b1) protrudes downward in vertical height from the working surface of the bottom cutting tooth (3a1) of the outer rotary cutting power sleeve (3a), with a downward protrusion difference of 0.5mm to 1.0mm.

4. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 3, characterized in that, The outer cylindrical surface of the outer rotary cutting power sleeve (3a) is provided with a spiral chip removal groove; The cutting teeth (3a1) are formed by alternating diamond composite sheets and cemented carbide wear-resistant blocks.

5. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 4, characterized in that, It also includes a chip removal system (6); The chip removal system (6) includes an annular dust collection hood (6a) sleeved outside the outer rotary cutting power sleeve (3a), and the annular dust collection hood (6a) is connected to an external negative pressure suction chip removal pipe (6a1).

6. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 3, characterized in that, The inner static constraint sleeve (3b) has a hollow negative pressure interlayer air chamber (3b2) inside, and the inner side wall of the inner static constraint sleeve (3b) has micropores that connect the hollow negative pressure interlayer air chamber (3b2) with the inner cavity of the sleeve. The hollow negative pressure interlayer air chamber (3b2) is connected to an external negative pressure source through a connecting pipe, and is used to adsorb the latex film onto the inner wall of the inner static constraint sleeve (3b) through negative pressure; The hollow negative pressure interlayer air chamber (3b2), micropores, connecting pipes and external negative pressure source together constitute the negative pressure membrane assembly (4).

7. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 6, characterized in that, A deep groove ball ceramic bearing (3a2) is provided in the gap between the inner static constraint sleeve (3b) and the outer rotary cutting power sleeve (3a). The anti-rotation component includes an anti-rotation guide rod (3b3), one end of which is connected to the inner static restraint sleeve (3b), and the other end is inserted through the lifting beam (1d). The lifting beam (1d) is vertically provided with a vertical limiting hole for the anti-slip guide rod (3b3).

8. The apparatus for preparing coarse-grained undisturbed soil triaxial samples to prevent particle stripping according to claim 1, characterized in that, A mechanical sensor (7) is installed in series at the force-bearing node connecting the propulsion mechanism (2) and the lifting beam (1d). The mechanical sensor (7) is used to detect the cutting reaction force of the sample and is connected to the controller to adaptively adjust the propulsion speed of the propulsion mechanism (2).

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