Deep-sea soft clay triaxial sample preparation device and preparation method

Abstract

The invention discloses a deep-sea soft clay triaxial sample preparation device and a preparation method, the deep-sea soft clay triaxial sample preparation device comprises a frame, a sample cylinder, and a compaction debristling module and a pressurization module which are mounted on the frame, the sample cylinder is detachably and fixedly connected to the bottom of the inner side of the frame and is used for loading a sample; the compaction and debristling module is arranged to be capable of automatically performing compaction operation on a sample in the sample barrel and performing debristling operation on the compacted sample to form a sample, and the pressurization module is arranged to be capable of applying surrounding pressure to the sample and applying pressure to the interior of the sample so as to enable the sample to reach a saturated and consolidated state; the compacted and debristled test sample is saturated and consolidated through the pressurizing module, so that the test sample can reach a saturated state under a high-pressure condition, the real state of the deep-sea soft clay triaxial test sample in a deep-sea environment can be simulated, and the quality of the test sample is improved; the driver drives the pressing plate to move up and down and cooperates with real-time detection of the first displacement sensor, and automatic and accurate control over the compaction strength and the compaction height is achieved.

Description

Technical Field

[0001] The present invention relates to the field of marine geotechnical engineering technology, and in particular to a deep-sea soft clay triaxial sample preparation device and a preparation method. Background Art

[0002] The triaxial test simulates the pressure conditions in the deep sea environment and measures the stress-strain relationship, shear strength, pore water pressure and other parameters of the soil sample, which can accurately evaluate the mechanical properties and deformation behavior of deep-sea soft clay. A deep understanding of these properties is of guiding significance for the construction of marine structures.

[0003] Due to the complex sedimentary environment, deep-sea soft clay has the characteristics of high water content, high porosity and high liquid and plastic limits. It is often difficult for the original deep-sea soft clay samples to maintain their natural structure and moisture state during collection and transportation, and they are prone to structural damage and water loss. Remolded soil can obtain a more stable and uniform physical state, which is conducive to ensuring the repeatability of the test and the accuracy of the results. Therefore, choosing remolded soil for triaxial testing can effectively eliminate the difficulties and uncertainties in obtaining the original state of deep-sea soft clay samples, while ensuring the reliability of the test data.

[0004] The triaxial test using remolded soil requires the preparation of triaxial specimens, and the preparation quality of triaxial specimens has a significant impact on the test results. The existing triaxial specimen preparation device is difficult to simulate the stress state of deep-sea soft clay in the real seabed environment, and cannot maintain the high-pressure environment of deep-sea soft clay, which affects the quality of triaxial specimen preparation. In addition, although the traditional layered compaction sample preparation is simple to operate, there are many problems. The impact force generated by the compaction hammer may produce sealed bubbles and excess pore water pressure in the soil body, resulting in uneven sample density and stratification. Before adding the next layer of soil sample, it is necessary to plane the soil. The current planing method is mostly manual planing, which is time-consuming, labor-intensive, and inconvenient. There are also large deviations in the planing depth and area. In addition, the original soil layer surface is not over-planed before adding the next layer of soil sample, which is easy to cause the sample to break or stratify, and it is also easy to cause different interlayer contact areas and bonding viscosities, affecting the quality of the triaxial specimen. In addition, in order to control the compaction thickness of each layer, the manual sample mold needs to be repeatedly measured and carefully operated during sample preparation, resulting in low sample preparation efficiency.

[0005] Therefore, a deep-sea soft clay triaxial specimen preparation device and preparation method are urgently needed to solve the above technical problems. Summary of the invention

[0006] The present invention aims to solve the above-mentioned technical problems, namely, to solve the following problems: first, the existing triaxial sample preparation device is difficult to simulate the stress state of deep-sea soft clay in a real seabed environment, and cannot maintain the high-pressure environment of deep-sea soft clay; second, the impact force generated by the compaction hammer may generate sealed bubbles and excess pore water pressure in the soil body, resulting in uneven density and stratification of the sample; third, the current manual planing is time-consuming and labor-intensive, and there are also large deviations in the planing depth and area, which can easily lead to sample fracture or stratification, and also easily lead to different contact areas and bonding viscosities between layers, affecting the quality of the triaxial sample; fourth, in order to control the compaction thickness of each layer, the manual sample making mold needs to be repeatedly measured and carefully operated when making the sample, resulting in the problem of low sample making efficiency.

[0007] To this end, in a first aspect, the present invention provides a deep-sea soft clay triaxial sample preparation device, comprising a frame, a sample barrel, a compaction and shaving module and a pressurizing module installed on the frame, wherein the sample barrel is detachably and fixedly connected to the bottom of the inner side of the frame for loading the sample, the compaction and shaving module is configured to automatically compact the sample in the sample barrel and shave the compacted sample to form a sample, and the pressurizing module is configured to apply ambient pressure to the sample and apply pressure to the inside of the sample to make the sample reach a saturated and consolidated state.

[0008] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial specimen preparation device, the pressurization module includes a base and a surrounding pressure pressurization system, the base is detachably fixedly connected to the bottom inside the frame, the base is used to place the sample with the outer periphery wrapped by the rubber film, the surrounding pressurization system includes a pressure chamber, a confining pressure controller and a confining pressure pipeline, the pressure chamber is detachably fixedly connected to the bottom inside the frame and covers the base, the top of the pressure chamber is provided with an openable and closable exhaust hole, the confining pressure controller is connected to the inside of the pressure chamber through the confining pressure pipeline, and the confining pressure pipeline is provided with a confining pressure valve.

[0009] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, a drainage pipe that penetrates the bottom wall of the frame and extends to the outside is provided on the base, a pore pressure sensor and a drainage valve are installed on the drainage pipe, the pressurization module also includes a back-pressure pressurization system, the back-pressure pressurization system includes a back-pressure controller, a back-pressure pipe, and a top cap, the back-pressure controller is connected to the back-pressure water inlet in the top cap through the back-pressure pipe, a back-pressure valve is installed on the back-pressure pipe, a lower permeable stone, a sample, an upper permeable stone and a top cap are placed on the base from bottom to top, the top and bottom ends of the rubber membrane on the periphery of the sample are respectively bound to the top cap and the base, and filter paper is arranged between the upper permeable stone and the sample and between the lower permeable stone and the sample.

[0010] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, the compaction and haircutting module includes a driver, a pressure plate and a haircutting assembly, the driver is installed at the top of the frame, the interior of the pressure plate is a hollow structure, the pressure plate is sleeved on the outside of the haircutting assembly, the haircutting assembly is connected to the driver, and the driver is configured to drive the pressure plate to move up and down for compaction operations and drive the haircutting assembly to move up and down and rotate relative to the pressure plate so as to extend out of the pressure plate for haircutting operations.

[0011] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, the driver is connected to the planing assembly through a force transmission rod, and the planing assembly includes a rotating rod, a planing plate and a planing tip, the rotating rod is detachably fixed to the bottom end of the force transmission rod, the bottom end of the rotating rod extends into the interior of the pressure plate and is fixed with a planing plate, and a plurality of evenly distributed planing tips are fixed to the bottom end of the planing plate, the planing plate and the pressure plate are connected by at least two telescopic rods, the bottom end of the pressure plate is provided with a planing opening that enables the planing tip to extend to the outside of the pressure plate, and an insertion rod that passes through the force transmission rod and the rotating rod is provided above the pressure plate, and during the compaction operation, the insertion rod is in contact with the top of the pressure plate.

[0012] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, the compaction planing module also includes a first displacement sensor for detecting the compaction height, and the first displacement sensor is installed in the frame at a position corresponding to the pressure plate.

[0013] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, a sample loading module is arranged on the frame, and the sample loading module includes a sample loader and a conveying channel. The sample loader is fixed at the top end of the frame and the bottom end extends into the inner side of the frame. A discharge port is arranged at the bottom end of the sample loader, and a first solenoid valve is installed on the discharge port. The conveying channel is detachably connected to the frame and is located on one side of the sample barrel. The conveying channel is inclined toward the direction of the sample barrel. The sample in the sample loader falls on the conveying channel and can slide into the sample barrel under the action of gravity.

[0014] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, the sample loading module also includes two support rods, the two support rods are fixed in parallel to the bottom of the frame, and the conveying channel is clamped on the two support rods through a clamping assembly.

[0015] In a specific embodiment of the above-mentioned deep-sea soft clay triaxial sample preparation device, the deep-sea soft clay triaxial sample preparation device also includes a control module, which is respectively connected to the compaction and planing module, the pressurization module and the loading module to control the corresponding compaction, planing, application of ambient pressure, application of pressure to the inside of the sample and automatic loading operations.

[0016] In a second aspect, the present invention further provides a method for preparing a deep-sea soft clay triaxial sample, which is prepared using the deep-sea soft clay triaxial sample preparation device as described in any one of the first aspects, and the preparation method comprises the following steps: Prepare deep-sea soft clay samples according to dry density requirements, and divide the prepared samples into corresponding portions according to the preset total compaction times; After the first sample is added into the sample tube, the compaction and depilation module is controlled to first perform a compaction operation. After the compaction operation is completed, the compaction and depilation module is controlled to perform a depilation operation on the compacted sample. After the depilation operation is completed, the second sample is added into the sample tube, and the compaction and depilation operations are repeated until the last sample is loaded into the sample tube and the compaction and depilation operations are completed. The sample is evacuated to achieve primary saturation using the evacuation saturation method; When the drainage pipe is filled with water and the specimen and the pressure chamber are installed, the confining pressure valve on the confining pressure pipe is controlled to open and the confining pressure controller is controlled to inject water into the pressure chamber until the water fills the entire pressure chamber and the confining pressure reaches the initial confining pressure value; When the initial confining pressure value is reached, the back pressure valve is opened, and the back pressure controller and the confining pressure controller are controlled to apply confining pressure and back pressure to the sample step by step from small to large according to the preset multi-level pressure values, until the ratio of the pore pressure increment to the confining pressure increment of the sample is greater than or equal to the set value, then it is considered that the saturation state is reached; wherein, the pressure value of each level of back pressure is always smaller than the pressure value of the confining pressure, and the difference is the set difference value; When the saturation state is reached, the back pressure controller is controlled to keep the back pressure value of the sample unchanged, and the confining pressure controller is controlled to apply a confining pressure value corresponding to the actual engineering stress to the sample. Then the volume change of water in the back pressure controller is detected in real time. When the volume change in the back pressure controller is less than or equal to the set volume value within the set time, it is considered that the drainage and consolidation of the sample are completed. At this time, the confining pressure valve and the back pressure valve are closed, and the sample production is completed.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The compacted and planed samples are saturated and consolidated through the pressurization module to ensure that the samples can reach a saturated state under high pressure conditions, which can simulate the real state of deep-sea soft clay triaxial samples in the deep-sea environment and improve the sample quality.

[0018] 2. The driver drives the pressing plate to move up and down and cooperates with the real-time detection of the first displacement sensor to realize automatic and accurate control of the compaction strength and compaction height, ensuring that the compaction height of each layer of soil sample is consistent with the overall sample density, avoiding errors caused by manual operations and the occurrence of sample stratification, and ensuring the reliability and consistency of the quality of different batches of samples; in addition, the present invention arranges a bottom plate and a planing tip to automatically plan the surface of the soil sample, avoiding the problem of inconsistent planing depth and area of ​​different layers caused by manual planing, and saving manpower, and the planing tip is arranged on the inner side of the pressing plate, and only extends from the inside of the pressing plate during planing, thereby reducing space occupancy.

[0019] 3. The present invention uses the first displacement sensor to automatically determine the compaction height. Under the premise of ensuring that the compaction height of each layer is the same, there is no need for manual repeated measurement, thereby improving the sample preparation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which: Figure 1 It is a schematic diagram of the overall structure of the compaction planing module in the deep-sea soft clay triaxial sample preparation device provided by the present invention; Figure 2 It is a schematic diagram of the overall structure of the pressurizing module in the deep-sea soft clay triaxial sample preparation device provided by the present invention; Figure 3 yes Figure 1 A partial cross-sectional view of the middle rotating rod and the pressing plate in a compacted state; Figure 4 yes Figure 1 A partial cross-sectional view of the middle rotating rod, the planing assembly and the pressing plate in the planing state; Figure 5 yes Figure 1 The structural diagram of the middle conveying channel; Figure 6 It is a structural diagram of the planing tip in the present invention; Figure 7 It is a schematic diagram of the control module structure of the present invention.

[0021] List of reference numerals: 1. Driver; 2. Force transmission rod; 3. First displacement sensor; 4. Rotating rod; 5. Pressing plate; 6. Sample tube; 7. Sample; 8. Display; 9. Electric control box; 10. Bottom plate; 11. Support rod; 12. Sample loader; 13. Conveying channel; 14. Frame; 15. Drainage pipe; 16. Back pressure controller; 17. Confining pressure controller; 18. Confining pressure valve; 19. Pore pressure sensor; 20. Drainage valve; 21. Base; 22. Permeable stone; 23. Pressure chamber; 24. Sample; 25. Back pressure pipe; 26. Top cap; 27. Exhaust hole; 28 , back pressure valve; 29, confining pressure pipeline; 30, plug rod; 31, telescopic rod; 32, planing board; 33, planing tip; 34, planing mouth; 35, radial hole; 36, limit block; 37, limit groove; 38, first adjusting knob; 39, second adjusting knob; 40, back pressure signal transmitter; 401, back pressure signal connector; 41, confining pressure signal transmitter; 411, confining pressure signal connector; 42, third adjusting knob; 43, fourth adjusting knob; 44, fifth adjusting knob; 45, first solenoid valve; 46, second solenoid valve; 47, solenoid switch. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are used to define components, only for the convenience of distinguishing the above components, and unless otherwise stated, the above terms have no special meanings and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The present invention relates to the field of marine geotechnical engineering technology, and in particular to a deep-sea soft clay triaxial sample preparation device and preparation method. The purpose is to solve the following problems: First, the existing triaxial sample preparation device is difficult to simulate the stress state of deep-sea soft clay in a real seabed environment, and cannot maintain the high-pressure environment of deep-sea soft clay; second, the impact force generated by the compacting hammer may generate sealed bubbles and excess pore water pressure in the soil body, resulting in uneven sample density and stratification; third, the current manual planing is time-consuming and labor-intensive, and there are also large deviations in the planing depth and area, which can easily lead to sample fracture or stratification, and also easily lead to different interlayer contact areas and bonding viscosities, affecting the quality of the triaxial sample; fourth, in order to control the compaction thickness of each layer, the manual sample mold needs to be repeatedly measured and carefully operated when preparing the sample, resulting in the problem of low sample preparation efficiency. For this purpose, the present invention provides a deep-sea soft clay triaxial sample preparation device and preparation method, including a frame, a sample tube, a compaction and shaving module installed on the frame, and a pressurizing module, wherein the sample tube is detachably fixedly connected to the bottom of the inner side of the frame for loading the sample, the compaction and shaving module is configured to automatically compact the sample in the sample tube and shave the compacted sample to form a sample, and the pressurizing module is configured to apply ambient pressure to the sample and apply pressure to the inside of the sample so that the sample reaches a saturated and consolidated state, and the sample after compaction and shaving is saturated and consolidated by the pressurizing module to ensure that the sample can reach a saturated state under high pressure conditions, and can simulate the real state of the deep-sea soft clay triaxial sample in the deep-sea environment, thereby improving the quality of the triaxial sample. The driver drives the pressing plate to move up and down and cooperates with the first displacement sensor to implement detection, so as to realize automatic and precise control of the compaction strength and compaction height, ensure that the compaction height of each layer of soil sample is consistent with the overall sample density, avoid errors caused by manual operation and the occurrence of sample stratification, and ensure the reliability and consistency of the quality of different batches of samples.

[0026] Below, the deep-sea soft clay triaxial specimen preparation device and preparation method provided by the embodiment of the present invention are described in detail with reference to the accompanying drawings.

[0027] See also Figure 1-2 The present invention provides a deep-sea soft clay triaxial sample 24 preparation device, comprising a frame 14, a sample tube 6, a compaction and shaving module and a pressurizing module installed on the frame 14, the sample tube 6 is detachably fixedly connected to the bottom of the inner side of the frame 14 for loading the sample 7, the compaction and shaving module is configured to automatically compact the sample 7 in the sample tube 6 and shave the compacted sample 7 to form the sample 24, and the pressurizing module is configured to apply ambient pressure to the sample 24 and apply pressure to the inside of the sample 24 to make the sample 24 reach a saturated and consolidated state.

[0028] Specifically, the frame 14 is a hollow steel structure frame 14, and the four side walls of the frame 14 are designed to be open, that is, there is no side wall wrapping, the top of the frame 14 is sealed by the top plate, and the bottom of the frame 14 is sealed by the bottom plate 10. The pressurization module and the compaction and depilation module are distributed in parallel on the bottom plate 10 inside the frame 14, and the frame 14 corresponding to the pressurization module is provided with holes to facilitate the pressurization module to enter and exit the frame 14.

[0029] In one embodiment, a loading module is provided on the frame 14, and the loading module includes a loading device 12 and a conveying channel 13. The loading device 12 is fixed on the top of the frame 14 and the bottom end extends into the inner side of the frame 14, that is, the loading device 12 is fixed on the top plate, and a discharge port is provided at the bottom end of the loading device 12, and a first solenoid valve 45 is installed on the discharge port. The conveying channel 13 is detachably connected in the frame 14 and is located on one side of the sample tube 6. The conveying channel 13 is inclined toward the sample tube 6, and the sample 7 in the loading device 12 falls on the conveying channel 13 and can slide into the sample tube 6 under the action of gravity.

[0030] In a specific implementation of the above embodiment, the connection between the conveying channel 13 and the frame 14 is: the sample loading module also includes two support rods 11, and the two support rods 11 are fixed in parallel at the bottom of the frame 14, and the branch conveying channel 13 is clamped on the two support rods 11 through a clamping assembly.

[0031] Specifically, the support rods 11 and the bottom plate 10 of the frame 14 are detachably fixedly connected by bolts. The heights of the two support rods 11 are different so that the delivery channel 13 can be tilted toward the sample tube 6 when it is stuck on them. Figure 1 As shown, the angle between the central axis of the conveying channel 13 and the horizontal line can be 30°. The clamping assembly includes a limit groove 37 and a limit plug. Two limit grooves 37 arranged in parallel are fixed at the bottom of the conveying channel 13 along the conveying direction. Each limit groove 37 is composed of two limit blocks 36. The two limit blocks 36 are fixed at the bottom end of the conveying channel 13, and there is a gap between the two limit blocks 36 to form the limit groove 37. Figure 5 As shown, a limiting plug that can be inserted into the limiting groove 37 is fixed on the opposite side walls of the two support rods 11, so that when the conveying channel 13 is placed on the two support rods 11, the limiting groove 37 is stuck on the limiting plug, limiting the displacement of the conveying channel 13 along the conveying direction. When disassembling, it is only necessary to lift the conveying channel 13 upward. The support rods 11 realize a detachable connection with the bottom end of the frame 14. In this way, the conveying channel 13 is disassembled before taking out the sample 24 in the sample tube 6 to avoid affecting the removal of the sample 24 in the sample tube 6.

[0032] In one embodiment, see Figure 1 , Figure 3-4The compaction and dehairing module includes a driver 1, a pressing plate 5 and a dehairing assembly. The driver 1 is installed at the top of the frame 14. The interior of the pressing plate 5 is a hollow structure. The pressing plate 5 is sleeved on the outside of the dehairing assembly. The dehairing assembly is connected to the driver 1. The driver 1 is configured to drive the pressing plate 5 to move up and down for compaction operations and drive the dehairing assembly to move up and down and rotate relative to the pressing plate 5 so as to extend from the pressing plate 5 for dehairing operations.

[0033] Specifically, the driver 1 is connected to the planing assembly through a force transmission rod 2, see Figure 3 , Figure 4 and Figure 6 The planing assembly includes a rotating rod 4, a planing plate 32 and a planing tip 33. The rotating rod 4 is detachably fixed to the bottom end of the force transmission rod 2. The bottom end of the rotating rod 4 extends into the interior of the pressing plate 5 and is fixed with a planing plate 32. The bottom end of the planing plate 32 is fixed with a plurality of evenly distributed planing tips 33. The planing plate 32 is connected to the pressing plate 5 by at least two telescopic rods 31. The bottom end of the pressing plate 5 is provided with a planing opening 34 that enables the planing tip 33 to extend to the outside of the pressing plate 5. The top of the pressing plate 5 is provided with an insertion rod 30 that passes through the force transmission rod 2 and the rotating rod 4. The axis of the insertion rod 30 is perpendicular to the axis of the force transmission rod 2. The axis of the force transmission rod 2 coincides with the axis of the rotating rod 4. During the compaction operation, the insertion rod 30 fits with the top end of the pressing plate 5. The force transmission rod 2 drives the insertion rod 30 to apply downward pressure to the pressing plate 5 to achieve the compaction operation of the pressing plate 5 on the sample 7. The rotating rod 4 and the force transmission rod 2 are provided with a communicating radial hole 35 for inserting the insertion rod 30 , and the center line of the radial hole 35 is perpendicular to the axis of the rotating rod 4 .

[0034] More specifically, the top of the pressing plate 5 is provided with a through hole communicating with the inside, and the rotating rod 4 passes through the through hole and extends into the inside of the pressing plate 5, and the rotating rod 4 and the planing plate 32 can be an integrated structure. The length of the insertion rod 30 is greater than the diameter of the through hole. The top of the rotating rod 4 is provided with a slot, and the bottom end of the force transmission rod 2 is inserted into the slot and fixed by bolts. The driver 1 includes a cylinder, a motor, a first bevel gear and a second bevel gear. The force transmission rod is a spline shaft. The second bevel gear is rotatably connected to the top of the frame, and the second bevel gear is provided with a through internal spline hole for meshing with the spline shaft. The force transmission rod passes through the internal spline hole. The motor and the cylinder are both installed at the top of the frame. The force transmission rod 2 is fixedly connected to the piston rod on the cylinder. The cylinder drives the force transmission rod 2 to move up and down. The output shaft of the motor is installed with a rotating shaft. The axis of the rotating shaft is perpendicular to the axis of the force transmission rod. The end of the rotating shaft is fixed with the first bevel gear. The first bevel gear is meshed with the second bevel gear. The motor drives the first bevel gear to rotate so that the second bevel gear drives the force transmission rod to rotate, thereby driving the rotating rod to rotate. The planing tip 33 includes a cylinder and a cone. The top of the cylinder is fixedly connected to the planing board 32, and the bottom of the cylinder is fixedly connected to the cone. The insertion rod 30 can be a pin.

[0035] In addition, in this application, see Figure 1 The compaction and hair removal module also includes a first displacement sensor 3 for detecting the compaction height. The first displacement sensor 3 is installed in the frame 14 at a position corresponding to the pressing plate 5. Exemplarily, the first displacement sensor 3 is a contact displacement sensor. When the cylinder drives the pressing plate 5 to the initial position, the lower end of the first displacement sensor 3 contacts the top of the pressing plate 5. The compaction height of the sample 7 in the sample tube 6 is calculated by detecting the descending height of the pressing plate 5, thereby achieving the purpose of automatically detecting and controlling the compaction height. Automatic and precise control of the compaction strength and compaction height is achieved, ensuring that the compaction height of each layer of soil sample is consistent with the density of the overall sample 24, avoiding errors caused by manual operations and the occurrence of stratification of the sample 24, and ensuring the reliability and consistency of the quality of different batches of samples 24.

[0036] The specific operation process of the compaction and depilation module is as follows: the compaction operation is that the driver 1 drives the force transmission rod 2 to move the rotating rod 4 and the pressure plate 5 downward, so that the pressure plate 5 contacts the sample 7 in the sample tube 6 and performs the compaction operation. The compaction height is detected by the first displacement sensor 3. When the required compaction height is reached, the compaction operation is stopped. At this time, the driver 1 drives the force transmission rod 2 to contract so that the pressure plate 5 moves upward to leave the sample tube 6, and then the depilation operation is performed, specifically, the insertion rod 30 is pulled out. At this time, the rotating rod 4 can move up and down relative to the pressure plate 5, and then the driver 1 drives the pressure plate 5 and the rotating rod 4 to move downward until the pressure plate 5 contacts the sample 7 in the sample tube 6. At this time, the pressure plate 5 does not move, and the depilation plate 32 drives the depilation tip 33 to continue to move downward, so that the depilation tip 33 extends out from the depilation port 34. After reaching the required extension length, the driver 1 drives the rotating rod 4 to rotate the depilation tip 33 on the depilation plate 32, thereby realizing the depilation operation. After the dehairing is completed, the driver 1 drives the pressing plate 5 and the dehairing assembly to move upward to separate from the sample tube 6, and continue the operation of adding the next layer of sample 7. After the sample 7 is compacted and dehaired by the compaction and dehairing module, it forms a sample 24 for the operation of the pressurizing module.

[0037] In one embodiment, see Figure 2 The pressurization module includes a base 21 and a surrounding pressure pressurization system. The base 21 is detachably fixedly connected to the bottom of the frame 14, that is, it is installed on the bottom plate 10 of the frame 14. The base 21 is used to place a sample 24 wrapped by a rubber film on the periphery. The surrounding pressurization system includes a pressure chamber 23, a confining pressure controller 17 and a confining pressure pipeline 29. The pressure chamber 23 is detachably fixedly connected to the bottom of the frame 14 and covers the base 21. An openable and closable exhaust hole 27 is provided at the top of the pressure chamber 23. The confining pressure controller 17 is connected to the inside of the pressure chamber 23 through the confining pressure pipeline 29. The confining pressure pipeline 29 is provided with a confining pressure valve 18.

[0038] In the above embodiment, the top of the pressure chamber 23 is provided with an exhaust hole 27 to ensure that the water can fill the entire pressure chamber 23. After the pressure chamber 23 is filled, the exhaust hole 27 can be closed. The switch of the exhaust hole 27 can be controlled by a valve, or a sealing plug can be screwed on the pressure chamber 23. These methods are all within the protection scope of this application. A hole is set at the top of the frame 14 corresponding to the pressure chamber 23 for the installation and removal of the pressure chamber 23. The confining pressure controller 17 injects water into the pressure chamber 23 through the confining pressure pipe 29 to increase the surrounding pressure of the sample 24.

[0039] In one embodiment, a drainage pipe 15 is provided on the base 21 and extends to the outside through the bottom wall of the frame 14. A pore pressure sensor 19 and a drainage valve 20 are installed on the drainage pipe 15. The pressurization module also includes a back-pressure pressurization system, which includes a back-pressure controller 16, a back-pressure pipe 25, and a top cap 26. The back-pressure controller 16 is connected to the back-pressure water inlet in the top cap 26 through the back-pressure pipe 25. A back-pressure valve 28 is installed on the back-pressure pipe 25. A lower permeable stone 22, a sample 24, an upper permeable stone 22 and a top cap 26 are placed on the base 21 in the pressure chamber 23 from bottom to top. The back-pressure pipe 25 extends into the pressure chamber 23. The top and bottom ends of the rubber membrane on the periphery of the sample 24 are respectively bound to the top cap 26 and the base 21. Filter paper is arranged between the upper permeable stone 22 and the sample 24 and between the lower permeable stone 22 and the sample 24. The back pressure controller 16 injects water into the sample 24 through the back pressure water inlet to achieve the purpose of applying pressure to the inside of the sample 24, which is referred to as back pressure operation in the subsequent description of this application.

[0040] In the present application, the bottom wall of the frame 14 refers to the bottom plate 10 of the frame 14. When the drain valve 20 is closed, the pore pressure sensor 19 is directly connected to the sample 24 and is consistent with the pressure inside the sample 24. Therefore, the pressure monitored by the pore pressure sensor 19 is the pore water pressure of the sample 24. The rubber membrane can be bound to the top cap 26 and the base 21 by a rubber ring to play a sealing role. The pressure chamber 23 can provide a closed environment, maintain the stability of the confining pressure and the back pressure, and ensure that the sample 24 is not disturbed by the outside world when it is saturated and consolidated.

[0041] The confining pressure controller 17 and the back pressure controller 16 are existing mature devices. The confining pressure controller 17 and the back pressure controller 16 can be generally composed of a stepper motor, a gear box, a push rod, a piston, a water storage chamber, a pressure sensor, and a second displacement sensor, and a display module. During the water absorption process, the stepper motor runs, controls the gear box to pull the push rod and the piston backward, the volume of the water storage chamber increases, and the water storage chamber forms a negative pressure, and the water is sucked into the water storage chamber. In the process of releasing water, the stepper motor controls the gear box to move the pull rod and the piston forward, squeeze the water in the water storage chamber, and discharge the water from the controller according to a predetermined pressure. The pressure sensor can detect the pressure value in the water storage chamber, and the second displacement sensor can detect the displacement of the push rod, and then calculate the volume of discharged or inhaled water; the display module can display the working status of the equipment, pressure, and water volume change and other information. Since the confining pressure controller 17 and the back pressure controller 16 are known mature equipment, they are prior art for those skilled in the art, so they will not be described in detail here.

[0042] In this application, see Figure 7 The deep-sea soft clay triaxial sample 24 preparation device also includes a control module, which is respectively connected to the compaction and planing module, the pressurization module and the loading module to control the corresponding compaction, planing, application of ambient pressure, application of pressure to the inside of the sample 24 and automatic loading operations.

[0043] Specifically, the control module includes an electric control box 9 and a display 8. The electric control box 9 is provided with a first adjustment knob 38, a second adjustment knob 39, a third adjustment knob 42, a fourth adjustment knob 43, a fifth adjustment knob 44, a back pressure signal transmitter 40 and a confining pressure signal transmitter 41. The display 8 is used to observe the compaction height of the sample 7 monitored by the first displacement sensor 3, the monitoring value of the pore water pressure sensor, the water pressure value and volume change injected into the pressure chamber 23 by the confining pressure controller 17, the water pressure value and volume change injected into the sample 24 by the back pressure controller 16, and the state of each adjustment knob. A control panel is installed inside the electric control box 9, which is used to receive the displacement monitored by the first displacement sensor 3, the pressure value monitored by the pore pressure sensor 19, and the control of the sample loader 12, the force transmission rod 2, the back pressure controller 16 and the confining pressure controller 17. The control panel converts the analog signals sent by the first displacement sensor 3 and the pore pressure sensor 19 into digital signals that can be received by the display 8, so that the display 8 displays the displacement monitored by the first displacement sensor 3 and the pressure value monitored by the pore pressure sensor 19.

[0044] like Figure 5 As shown, the first adjusting knob 38 is electrically connected to the first solenoid valve 45 through the control panel. The opening of the first solenoid valve 45 is controlled by rotating the first adjusting knob 38, thereby controlling the opening and closing of the discharge port of the sample loader 12.

[0045] The second adjusting knob 39 is electrically connected to the second electromagnetic valve 46 on the driver 1 for controlling the up and down movement of the pressing plate 5 through the control panel. The second electromagnetic valve is installed on the air pipe connected to the cylinder. The height of the pressing plate 5 can be controlled by turning the second adjusting knob 39. The third adjusting knob 42 is electrically connected to the electromagnetic switch 47 on the driver 1 for controlling the rotation of the force transmission rod 2 through the control panel. When the electromagnetic switch is turned on, the motor is powered on to drive the force transmission rod to rotate. When the electromagnetic switch is broken, the motor is powered off and the rotation stops.

[0046] The fourth adjusting knob 43 is electrically connected to the back pressure signal transmitter 40 through the control panel, and the back pressure signal transmitter 40 is connected to the back pressure controller 16 through the back pressure signal connector 401. The pressure value released or sucked by the back pressure controller 16 is controlled by the rotation angle of the fourth adjusting knob 43. The fourth adjusting knob 43 is rotated clockwise to change the pressure value released by the back pressure controller 16, and the fourth adjusting knob 43 is rotated counterclockwise to change the pressure value sucked by the back pressure controller 16. The released pressure value: water flows from the back pressure controller 16 to the inside of the sample 24 according to a predetermined pressure value, and the pressure of the back pressure controller 16 is transmitted to the sample 24. The pressure value released from the back pressure controller 16 can be controlled by the fourth adjusting knob 43. The absorbed pressure value: when the amount of water in the back pressure controller 16 is too little, water needs to be sucked from the outside. At this time, the water absorption pressure value of the back pressure controller 16 can be controlled by the fourth adjusting knob 43.

[0047] The fifth adjusting knob 44 is electrically connected to the confining pressure signal transmitter 41 through the control panel, and the confining pressure signal transmitter 41 is connected to the confining pressure controller 17 through the confining pressure signal connector 411. The pressure value released or inhaled by the confining pressure controller 17 is controlled by the rotation angle of the fifth adjusting knob 44. Rotating the fifth adjusting knob 44 clockwise changes the pressure value released by the confining pressure controller 17, and rotating the fifth adjusting knob 44 counterclockwise changes the pressure value inhaled by the confining pressure controller 17.

[0048] On the other hand, the present application also provides a method for preparing a deep-sea soft clay triaxial sample, which is prepared using the deep-sea soft clay triaxial sample preparation device in the above various embodiments. The preparation method comprises the following steps: S1, preparing a deep-sea soft clay sample 7 according to the dry density requirement, and dividing the prepared sample 7 into corresponding portions according to a preset total number of compaction times; In step S1 , the preset total number of compaction times is set according to the experimental requirements. For example, the configured sample 7 is divided into five equal parts, that is, the sample 7 is added into the sample tube 6 in five times.

[0049] S2, after adding the first sample 7 into the sample tube 6, the compaction and planing module is controlled to first perform a compaction operation, and after the compaction operation is completed, the compaction and planing module is controlled to perform a planing operation on the compacted sample 7, and after the planing operation is completed, the second sample 7 is added into the sample tube 6, and the compaction and planing operations are repeated until the last sample 7 is loaded into the sample tube 6 and the compaction and planing operations are completed; In step S2, after the compaction operation is completed, the material is left to stand for a preset time, and then the planing operation is performed. The preset time can be set to 5 to 10 minutes. For example, the preset time is 5 minutes or 7 minutes.

[0050] S3, using the air saturation method to evacuate the sample 24 to achieve primary saturation; Specifically, the sample 24 is taken out of the sample tube 6 and placed in the vacuum cylinder for vacuum saturation. When the vacuum time reaches the set vacuum time, it stops, that is, the sample 24 reaches the primary saturation state. The vacuum saturation method is implemented in accordance with the "Standard for Geotechnical Test Methods" (GB / T50123-2019).

[0051] S4, when the drainage pipe 15 is filled with water and the sample 24 and the pressure chamber 23 are installed, the confining pressure valve 18 on the confining pressure pipe 29 is controlled to open and the confining pressure controller 17 is controlled to inject water into the pressure chamber 23 until the water fills the entire pressure chamber 23 and the confining pressure reaches the initial confining pressure value; the filter paper is moistened with water before being placed; The specific installation steps of the sample 24 are as follows: place the lower permeable stone 22, filter paper, the primary saturated sample 24, filter paper, the upper permeable stone 22 and the top cap 26 on the base 21 in sequence, wrap the rubber membrane around the outer axis of the sample 24 and tie the top end of the rubber membrane to the top cap 26, and tie the bottom end of the rubber membrane to the base 21.

[0052] S5, when the initial confining pressure value is reached, the back pressure valve 28 is opened, and the back pressure controller 16 and the confining pressure controller 17 are controlled to apply confining pressure and back pressure to the sample 24 step by step from small to large according to the preset multi-level pressure values, until the ratio of the pore pressure increment to the confining pressure increment of the sample 24 is greater than or equal to the set value, then it is considered that the saturation state is reached; wherein, the pressure value of each level of back pressure operation is always smaller than the pressure value of the confining pressure, and differs by a set difference, and after each level of confining pressure and back pressure is applied, the next level of confining pressure and back pressure value are applied after the pore pressure value is stabilized; the back pressure controller 16 injects water into the sample 24 through the back pressure water inlet to adjust the pressure value of the back pressure.

[0053] The specific value of the difference is not limited in this application. It is designed according to actual requirements. In this application, the difference is set to 20KPa by way of example. The purpose of graded saturation (gradual application of confining pressure and back pressure) is to reduce the disturbance of the saturation process to the sample 24 and avoid the influence of excessive pressure on the morphology of the sample 24. This is a relatively safe and reliable saturation method. After each level of pore pressure is stable, it indicates that the saturation of this level has been completed and the next level of saturation (i.e., the application of the next level of confining pressure and back pressure) can be carried out. Exemplarily, the initial confining pressure value is set to 20 kPa. When the confining pressure and back pressure are applied in stages, the back pressure value increases from 50 kPa by 50 kPa at each stage until it reaches 400 kPa. The corresponding confining pressure value increases from 70 kPa by 50 kPa at each stage until it reaches 420 kPa. After the pore pressure of each stage is stabilized, the confining pressure and back pressure of the next stage are applied.

[0054] S6, when the saturation state is reached, the back pressure controller 16 is controlled to keep the back pressure value of the sample 24 unchanged, and the confining pressure controller 17 is controlled to apply the confining pressure value corresponding to the actual engineering stress to the sample 24, and then the volume change of the water in the back pressure controller 16 is detected in real time. When the volume change in the back pressure controller 16 is less than or equal to the set volume value within the set time, it is considered that the drainage and consolidation of the sample 24 is completed, and the confining pressure valve 18 and the back pressure valve 28 are closed at this time, and the sample 24 is completed. The purpose of drainage consolidation is to simulate the stress state of the sample 24 under the real seabed environment conditions.

[0055] Before executing step S4, some water is sucked into the confining pressure controller 17 and the back pressure controller 16 to ensure that sufficient water pressure can be provided when the back pressure is saturated and consolidated. The ratio of the pore pressure increment to the confining pressure increment can be calculated through the control panel inside the electric control box 9, and the change trend of the drainage consolidation amount over time in step S6 is obtained through the volume change of the back pressure controller 16. During the drainage consolidation process, water flows from the inside of the sample 24 to the back pressure controller 16, causing the volume of the water storage chamber in the back pressure controller 16 to increase and the displacement of the push rod to decrease. The volume change of the back pressure controller 16 is calculated by the reduction in the displacement of the push rod detected by the second displacement sensor installed on the back pressure controller 16.

[0056] In the present application, the step of adding the sample 7 into the sample tube 6 in step S2 is specifically as follows: the first electromagnetic valve 45 is controlled by the control module to open the discharge port of the sample loader 12, and then the sample 7 falls onto the conveying channel 13, slides into the sample tube 6 through the conveying channel 13, and achieves the first loading. After the loading is completed, the first electromagnetic valve 45 is controlled to close the discharge port, the conveying channel 13 is removed, and then the compaction operation is performed. A sample 7 is pre-loaded in the sample loader 12.

[0057] The specific steps of the compaction operation are as follows: the driver 1 drives the force transmission rod 2 to move the rotating rod 4 and the pressure plate 5 downward. During the downward movement of the pressure plate 5, the sample 7 in the sample tube 6 is contacted to perform the compaction operation. During the downward movement of the pressure plate 5, the first displacement sensor 3 detects the downward movement height. The control panel calculates the compaction height through the downward movement height information detected by the first displacement sensor 3. When the required compaction height is reached, the compaction operation is stopped. At this time, the driver 1 drives the force transmission rod 2 to contract and the pressure plate 5 moves upward to leave the sample tube 6, and stands for a preset time. During the standing period, the insertion rod 30 is moved from the rotating The rod 4 is pulled out, so that the rotating rod 4 can move up and down relative to the pressing plate 5. After the static time is reached, the planing operation is performed. Specifically, the driver 1 drives the force transmission rod 2 to move the rotating rod 4 and the pressing plate 5 downward until the pressing plate 5 contacts the sample 7 in the sample tube 6. After that, the pressing plate 5 does not continue to move downward, and the planing plate 32 drives the planing tip 33 to continue to move downward, so that the planing tip 33 extends out of the planing port 34. After the required extension length is reached, the driver 1 drives the rotating rod 4 to rotate the planing tip 33 on the planing plate 32, thereby realizing the planing operation, and planing is performed according to the preset planing time. After the planing is completed, the driver 1 drives the pressing plate 5 and the planing assembly to move upward to separate from the sample tube 6, and continues the next layer of sample 7 addition, compaction and planing operations until the last compaction and planing operations are completed to form a sample 24 for use by the pressurization module.

[0058] The length of the planing tip 33 extending out of the planing mouth 34 can be detected by a pressure sensor. A pressure sensor is installed at the center of the bottom end of the planing board 32. When the planing board 32 contacts the bottom of the pressing plate 5 and continues to move downward, the pressure sensor will detect the pressure information. When the pressure information changes, it means that the planing tip 33 has reached the required length. At this time, the downward movement operation is stopped, and the driver 1 can drive the planing tip 33 to rotate in a circumferential direction.

[0059] It should be noted that before the sample 7 is loaded into the sample tube 6 , a thin layer of vaseline is applied to the inner wall of the sample tube 6 . The vaseline can ensure that the pressing plate 5 can move up and down smoothly and fill the gap between the pressing plate 5 and the sample tube 6 .

[0060] In step S4, before the specimen 24 is installed on the base 21, the drain valve 20 is opened, water is introduced from the drain valve 20, and flows out from the top of the base 21. This step can completely exhaust the air in the drain pipe 15 to ensure that the drain pipe 15 is full of water. Since the subsequent saturation process is saturated with water, if there is air in the drain pipe 15, it will affect the saturation speed and effect of the triaxial specimen 24, and further affect the quality of the specimen 24. The exhaust hole 27 of the pressure chamber 23 is in an open state before water is injected. When water fills the pressure chamber 23 and overflows from the exhaust hole 27, the exhaust hole 27 is closed. At this time, the pressure chamber 23 is in a closed state, and water injection continues until the initial confining pressure value is reached.

[0061] In the application, the compacted and shaved samples were saturated and consolidated through a pressurization module to ensure that the samples could reach a saturated state under high-pressure conditions. This can simulate the actual state of deep-sea soft clay triaxial samples in a deep-sea environment and improve the quality of the samples.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deep-sea soft clay triaxial sample preparation device, characterized in that: It includes a frame, a sample tube, a compaction and depilation module and a pressurizing module installed on the frame. The sample tube is detachably fixedly connected to the bottom of the inner side of the frame for loading samples. The compaction and depilation module is configured to automatically compact the sample in the sample tube and depilate the compacted sample to form a sample. The pressurizing module is configured to apply ambient pressure to the sample and apply pressure to the inside of the sample to make the sample reach a saturated and consolidated state.

2. The deep-sea soft clay triaxial sample preparation device according to claim 1, characterized in that: The pressurization module includes a base and a surrounding pressure pressurization system, wherein the base is detachably fixedly connected to the bottom of the frame, and the base is used to place a sample whose outer periphery is wrapped by a rubber film. The surrounding pressurization system includes a pressure chamber, a confining pressure controller and a confining pressure pipeline, wherein the pressure chamber is detachably fixedly connected to the bottom of the frame and covers the base, and an openable and closable exhaust hole is provided at the top of the pressure chamber, and the confining pressure controller is connected to the interior of the pressure chamber through the confining pressure pipeline, and a confining pressure valve is provided on the confining pressure pipeline.

3. The deep-sea soft clay triaxial sample preparation device according to claim 2, characterized in that: The base is provided with a drainage pipe which passes through the bottom wall of the frame and extends to the outside, and a pore pressure sensor and a drainage valve are installed on the drainage pipe. The pressurization module also includes a back-pressure pressurization system, which includes a back-pressure controller, a back-pressure pipe, and a top cap. The back-pressure controller is connected to the back-pressure water inlet in the top cap through the back-pressure pipe, and a back-pressure valve is installed on the back-pressure pipe. A lower permeable stone, a sample, an upper permeable stone and a top cap are placed on the base from bottom to top, and the top and bottom ends of the rubber membrane on the periphery of the sample are respectively bound to the top cap and the base, and filter paper is arranged between the upper permeable stone and the sample and between the lower permeable stone and the sample.

4. The deep-sea soft clay triaxial sample preparation device according to claim 1, characterized in that: The compaction and dehairing module includes a driver, a pressure plate and a dehairing assembly. The driver is installed at the top of the frame. The interior of the pressure plate is a hollow structure. The pressure plate is sleeved on the outside of the dehairing assembly. The dehairing assembly is connected to the driver. The driver is configured to drive the pressure plate to move up and down for compaction operations and drive the dehairing assembly to move up and down and rotate relative to the pressure plate so as to extend out of the pressure plate for dehairing operations.

5. The deep-sea soft clay triaxial sample preparation device according to claim 4, characterized in that: The driver is connected to the planing assembly through a force transmission rod, and the planing assembly includes a rotating rod, a planing board and a planing tip. The rotating rod is detachably fixed to the bottom end of the force transmission rod, and the bottom end of the rotating rod extends into the interior of the pressure plate and is fixed with a planing board, and a plurality of evenly distributed planing tips are fixed to the bottom end of the planing board. The planing board and the pressure plate are connected by at least two telescopic rods, and the bottom end of the pressure plate is provided with a planing opening that enables the planing tip to extend to the outside of the pressure plate, and an insertion rod that passes through the force transmission rod and the rotating rod is provided above the pressure plate. During the compaction operation, the insertion rod fits with the top end of the pressure plate.

6. The deep-sea soft clay triaxial sample preparation device according to claim 4, characterized in that: The compaction and shaving module further comprises a first displacement sensor for detecting the compaction height, wherein the first displacement sensor is installed in a position corresponding to the pressing plate in the frame.

7. The deep-sea soft clay triaxial sample preparation device according to claim 1, characterized in that: A sample loading module is arranged on the frame, and the sample loading module includes a sample loader and a conveying channel. The sample loader is fixed on the top of the frame and the bottom end extends into the inner side of the frame. A discharge port is arranged at the bottom end of the sample loader, and a first solenoid valve is installed on the discharge port. The conveying channel is detachably connected to the frame and is located on one side of the sample barrel. The conveying channel is inclined toward the sample barrel. The sample in the sample loader falls onto the conveying channel and can slide into the sample barrel under the action of gravity.

8. The deep-sea soft clay triaxial sample preparation device according to claim 7, characterized in that: The sample loading module further comprises two support rods, which are fixed in parallel to the bottom of the frame, and the conveying channel is clamped on the two support rods through a clamping assembly.

9. The deep-sea soft clay triaxial sample preparation device according to claim 7, characterized in that: The deep-sea soft clay triaxial sample preparation device also includes a control module, which is respectively connected to the compaction and planing module, the pressurization module and the sample loading module to control the corresponding compaction, planing, application of ambient pressure, application of pressure to the inside of the sample and automatic loading operations.

10. A method for preparing triaxial specimens of deep-sea soft clay, characterized in that: The preparation is performed using the deep-sea soft clay triaxial specimen preparation device as described in any one of claims 3 to 9, and the preparation method comprises the following steps: Prepare deep-sea soft clay samples according to dry density requirements, and divide the prepared samples into corresponding portions according to the preset total compaction times; After the first sample is added into the sample tube, the compaction and depilation module is controlled to first perform a compaction operation. After the compaction operation is completed, the compaction and depilation module is controlled to perform a depilation operation on the compacted sample. After the depilation operation is completed, the second sample is added into the sample tube, and the compaction and depilation operations are repeated until the last sample is loaded into the sample tube and the compaction and depilation operations are completed. The sample is evacuated to achieve primary saturation using the saturation method; When the drainage pipe is filled with water and the specimen and the pressure chamber are installed, the confining pressure valve on the confining pressure pipe is controlled to open and the confining pressure controller is controlled to inject water into the pressure chamber until the water fills the entire pressure chamber and the confining pressure reaches the initial confining pressure value; When the initial confining pressure value is reached, the back pressure valve is opened, and the back pressure controller and the confining pressure controller are controlled to apply confining pressure and back pressure to the sample step by step from small to large according to the preset multi-level pressure values, until the ratio of the pore pressure increment to the confining pressure increment of the sample is greater than or equal to the set value, then it is considered that the saturation state is reached; wherein, the pressure value of each level of back pressure is always smaller than the pressure value of the confining pressure, and the difference is the set difference value; When the saturation state is reached, the back pressure controller is controlled to keep the back pressure value of the sample unchanged, and the confining pressure controller is controlled to apply a confining pressure value corresponding to the actual engineering stress to the sample. Then the volume change of water in the back pressure controller is detected in real time. When the volume change in the back pressure controller is less than or equal to the set volume value within the set time, it is considered that the drainage and consolidation of the sample are completed. At this time, the confining pressure valve and the back pressure valve are closed, and the sample production is completed.

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