Calcareous sand saturation device for triaxial test

Abstract

The utility model discloses a calcareous sand saturation device for a triaxial test, and relates to the technical field of indoor geotechnical tests of geotechnical engineering. The device comprises a supporting sample bearing structure, a sealing sample preparation structure, a hydraulic pneumatic structure and a gas-liquid supply structure. The supporting sample bearing structure consists of a base, a sliding rod, an upper sliding table, a lower sliding table and a top table; the sealed sample preparation structure comprises a sealing assembly and a sample preparation assembly; the hydraulic pneumatic structure comprises a hydraulic assembly and a pneumatic assembly and is used for controlling lifting of the sliding table and pressure maintaining and air exhausting of the sealing assembly. The gas-liquid supply structure provides CO2 gas and gas-free water for sample saturation and discharges redundant gas and liquid. According to the utility model, through the lifting type sealing assembly structure and the stepped sealing design, and the sequential action of the negative pressure pump, carbon dioxide gas and gas-free water, air in a calcareous sand sample is effectively discharged, a highly saturated state is quickly achieved, the accuracy of a subsequent triaxial test result is remarkably improved, and the test efficiency is improved. The sealing performance is excellent, the operation is simple, and the structure is stable.

Description

Technical Field

[0001] This utility model relates to the field of indoor geotechnical testing technology in geotechnical engineering, specifically to a calcareous sand saturation device for triaxial testing. Background Technology

[0002] In the field of geotechnical engineering, triaxial testing is a classic testing method widely used to determine the mechanical properties of materials. Calcareous sand, a special type of soil and rock material widely distributed in the South China Sea, has physical and mechanical properties that are of great significance for island and reef engineering construction. However, current research on triaxial testing of calcareous sand still has some shortcomings.

[0003] In traditional triaxial tests, the saturation process for calcareous sand samples is cumbersome and it is difficult to ensure a high degree of saturation. Existing techniques mostly employ single head saturation or back pressure saturation methods, but these methods often fail to achieve the desired saturation for calcareous sand with abundant internal porosity. Although some studies have attempted to combine carbon dioxide with back pressure saturation, the lack of pre-reserved ports in the instrument's piping makes the operation cumbersome, requiring repeated disassembly and reassembly of pipe joints, increasing the complexity and time cost of the experiment.

[0004] In summary, existing technologies have many problems in the sample saturation process of triaxial tests on calcareous sand. There is an urgent need for a device and method that can efficiently and accurately achieve sample saturation of calcareous sand in order to improve the reliability of test results and test efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a calcium sand saturation device for triaxial testing to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides a triaxial test calcareous sand saturation device, comprising:

[0007] Support structure: includes a base, two sliding rods are spaced apart on the top of the base, an upper sliding platform and a lower sliding platform are slidably arranged on the two sliding rods, and a top platform is fixed between the top ends of the sliding rods;

[0008] Sealed sample preparation structure: includes a sealing assembly, the sealing assembly includes a cover platform and a cover body, the cover platform is fixed to the top of the lower slide platform, the top of the cover body is fixed to the bottom of the upper slide platform, and a sample preparation component is provided inside the sealing assembly;

[0009] Hydraulic-pneumatic structure: including hydraulic components for controlling the lifting and lowering of the upper and lower slides, and pneumatic components for maintaining pressure and evacuating air from the sealing components;

[0010] Gas-liquid supply structure: The gas-liquid supply structure provides CO2 gas and degassing water to the sample saturation and discharges excess gas and liquid from the sealing assembly.

[0011] Preferably, the cover is a transparent cover, which allows for easy observation of the internal condition of the sealing assembly.

[0012] Preferably, the bottom of the cover is provided with locking teeth, and the top outer ring of the cover platform is provided with locking grooves that cooperate with the locking teeth.

[0013] Preferably, the locking teeth are stepped locking teeth. The matching design of the locking teeth and the locking groove makes the connection between the cover and the cover platform tighter and more stable, effectively enhancing the sealing performance, preventing gas leakage, and ensuring the smooth progress of the saturation process.

[0014] Preferably, the sample preparation component includes a sample preparation component base, on which a three-lobed membrane is installed. Fastening clamps are provided at both the upper and lower ends of the outer wall of the three-lobed membrane. A calcareous sand sample is placed inside the three-lobed membrane. A rubber membrane is fitted onto the inner wall of the three-lobed membrane. Filter stones are provided at the top and bottom of the three-lobed membrane. Filter paper is provided between the three-lobed membrane and the filter stones. A filter stone groove is opened at the top of the base, and the filter stones and filter paper at the bottom of the three-lobed membrane are located within the filter stone groove.

[0015] Preferably, the hydraulic assembly includes a lower slide hydraulic press and an upper slide hydraulic press. The lower slide hydraulic press is located on the top of the base, and its telescopic end is fixedly connected to the bottom of the lower slide. The upper slide hydraulic press is located on the top of the top platform, and its telescopic end passes through the top platform and is fixedly connected to the top of the upper slide. Precise control of the upper and lower slides via the hydraulic presses enables smooth lifting and lowering movements, ensuring accurate installation and sealing of the sealing components, and improving operational stability and reliability.

[0016] Preferably, the pneumatic assembly includes a pressure-holding cylinder and a negative pressure pump, both located on the top of the upper slide. The telescopic end of the pressure-holding cylinder passes through the upper slide and the sealing assembly to compress the calcareous sand sample placed inside the sample preparation assembly. The negative pressure pump is equipped with a negative suction tube, the other end of which passes through the upper slide and is located inside the sealing assembly. The pressure-holding cylinder can apply stable pressure to the sample, ensuring its shape and position during the saturation process, while the negative pressure pump can effectively extract air from the sealing assembly, creating a negative pressure environment, which is beneficial for the introduction of carbon dioxide gas and the saturation of the sample.

[0017] Preferably, a pressure gauge is installed on the top of the upper slide, and the pressure gauge is used to display the air pressure status inside the sealing assembly.

[0018] Preferably, the gas-liquid supply structure includes a bracket mounted on a base, on which a CO2 delivery tank and a degassing water delivery tank are mounted. A confluence tee connects the gas outlet of the CO2 delivery tank and the water outlet of the degassing water delivery tank. A flexible conduit connects the confluence end of the confluence tee to the sample preparation assembly, and the other end of the flexible conduit connects to the sample preparation assembly. A first valve and a second valve are respectively installed on the gas outlet of the CO2 delivery tank and the water outlet of the degassing water delivery tank. This design enables a stable supply of CO2 gas and degassing water, and controls their flow rate and pressure through valves to meet the requirements of different stages of sample saturation, thereby improving the saturation effect.

[0019] Preferably, the gas-liquid supply structure includes a booster pump located at the top of the platform, with a booster pipe installed on the booster pump and connected to the degassing water delivery tank. The booster pump provides additional pressure for the degassing water delivery, ensuring that the degassing water can be smoothly forced into the sealing assembly, improving the efficiency and effectiveness of liquid saturation.

[0020] Preferably, the CO2 conveying tank is provided with an air inlet pipe, and the air inlet pipe is provided with an air inlet valve.

[0021] Preferably, the gas-liquid supply structure includes a drain hose located at the bottom of the sealing assembly, and the drain hose is provided with a drain valve.

[0022] Preferably, the triaxial test calcareous sand saturation device further includes a control panel, which is mounted on the side wall of the base. The signal output terminal of the control panel is connected to the signal receiving terminals of the lower slide hydraulic press, the upper slide hydraulic press, the pressure holding cylinder, and the negative pressure pump. The control panel enables centralized control of the entire device, allowing operators to conveniently operate various components, thus improving the convenience and automation of the test.

[0023] The beneficial effects of this utility model are:

[0024] 1. This utility model, through its innovative lifting-type sealing component structure and unique stepped sealing design, combined with the sequential action of a negative pressure pump, carbon dioxide gas, and degassed water, effectively removes air from the interior of calcareous sand samples, rapidly achieving a highly saturated state. During operation, the negative pressure pump first extracts air from the sealing component to create a negative pressure environment. Then, carbon dioxide gas is introduced, allowing it to fully penetrate the pores within the calcareous sand from the bottom upwards, expelling the air. Subsequently, degassed water is pressurized into the sealing component to maintain pressure and saturation, causing the carbon dioxide gas in the calcareous sand to dissolve in the degassed water, effectively eliminating porosity and ensuring the sample quickly reaches a highly saturated state, significantly improving the accuracy of subsequent triaxial test results.

[0025] 2. This invention boasts excellent sealing performance and is easy to operate. The saturated negative pressure transparent cover employs a stepped structure that is squeezed into the sealing component platform, with sealing gaskets added at the joints. Sealing is achieved through compression, resulting in not only excellent airtightness but also a more efficient sample preparation process for saturated specimens. The entire sealing process requires no complex operations, significantly shortening test preparation time and improving overall test efficiency. Simultaneously, this sealing method effectively prevents gas and liquid leakage, ensuring a stable environment for the sample during saturation, further enhancing test reliability.

[0026] 3. The sample support structure of this utility model is stable, the hydraulic and pneumatic structure precisely controls the lifting and lowering of the slide table and the pressure holding and gas extraction of the sealing components, and the gas-liquid supply structure stably supplies gas and liquid and discharges excess. All structures work together to ensure a stable and efficient sample preparation process. The combination of the base, slide rod, upper slide table, lower slide table, and top platform provides a stable support platform for the entire device, ensuring that the sample will not be affected by structural instability during operation. The hydraulic components, specifically the lower and upper slide table hydraulic presses, can precisely control the lifting and lowering of the slide table, while the pressure holding cylinder and negative pressure pump in the pneumatic components ensure pressure control and gas extraction during the sample saturation process. The gas-liquid supply structure, through the cooperation of the CO2 delivery tank and the degassing water delivery tank on the support, as well as the confluence tee pipe, flexible conduit, and other components, achieves precise delivery and control of gas and liquid, ensuring the smooth progress of the sample saturation process. Attached Figure Description

[0027] Figure 1 This is a structural diagram of the present invention;

[0028] Figure 2 This is a structural diagram of the sealing assembly of this utility model;

[0029] Figure 3 This is an exploded view of the sample preparation component of this utility model;

[0030] Figure label:

[0031] 1. Support structure, 11. Base, 12. Slide rod, 13. Upper slide, 14. Lower slide, 15. Top platform.

[0032] 2 sealing components, 21 cover platform, 211 slot, 22 cover body, 221 retaining teeth,

[0033] 3 Sample preparation assembly, 31 Sample preparation assembly base, 311 Filter stone tank, 32 Three-lobed membrane, 321 Fastening clamp, 322 Rubber membrane, 33 Filter stone, 34 Filter paper,

[0034] 4. Hydraulic and pneumatic structure; 41. Lower slide hydraulic press; 42. Upper slide hydraulic press; 43. Pressure holding cylinder; 44. Negative pressure pump; 441. Negative suction pipe.

[0035] 5. Gas-liquid supply structure; 51. Support frame; 52. CO2 delivery tank; 521. First valve; 522. Inlet pipe; 523. Inlet valve; 53. Airless water delivery tank; 531. Second valve; 54. Combination tee pipe; 55. Flexible conduit; 56. Booster pump; 561. Booster pipe; 57. Inlet pipe; 571. Inlet valve; 58. Drain hose; 581. Drain valve.

[0036] 6 control panels

[0037] 7. Calcareous sand samples. Detailed Implementation

[0038] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0039] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0040] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0042] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] Example

[0045] like Figures 1-3 The triaxial test calcareous sand saturation apparatus shown includes:

[0046] Support structure 1: includes a base 11, two sliding rods 12 are spaced apart on the top of the base 11, an upper sliding platform 13 and a lower sliding platform 14 are slidably arranged on the two sliding rods 12, and a top platform 15 is fixed between the top ends of the sliding rods 12.

[0047] Sealed sample preparation structure: includes a sealing component 2, which includes a platform 21 and a cover 22. The platform 21 is fixed to the top of the lower slide 14, and the top of the cover 22 is fixed to the bottom of the upper slide 13. A sample preparation component 3 is provided inside the sealing component 2. The bottom of the cover 22 is provided with a locking tooth 221, and the top outer ring of the platform 21 is provided with a locking groove 211 that cooperates with the locking tooth 221. The sample preparation component 3 includes a sample preparation component base 31, on which a three-lobed membrane 32 is installed. The upper and lower ends of the outer wall of the three-lobed membrane 32 are provided with fastening clamps 321. A calcium sand sample 7 is placed inside the three-lobed membrane 32. A rubber membrane 322 is fitted on the inner wall of the three-lobed membrane 32. Filter stones 33 are provided at the top and bottom of the three-lobed membrane 32. Filter paper 34 is provided between the three-lobed membrane 32 and the filter stones 33. A filter stone groove 311 is opened at the top of the base 31. The filter stones 33 and filter paper 34 at the bottom of the three-lobed membrane 32 are located in the filter stone groove 311.

[0048] Hydraulic-pneumatic structure 4: includes a hydraulic assembly for controlling the lifting and lowering of the upper slide 13 and the lower slide 14, and a pneumatic assembly for pressure holding and air extraction of the sealing assembly 2; the hydraulic assembly includes a lower slide hydraulic press 41 and an upper slide hydraulic press 42, the lower slide hydraulic press 41 is located on the top of the base 11, and the telescopic end of the lower slide hydraulic press 41 is fixedly connected to the bottom of the lower slide 14; the top of the top platform 15 is equipped with the upper slide hydraulic press 42, and the telescopic end of the upper slide hydraulic press 42 passes through the top platform 15 and is fixedly connected to the top of the upper slide 13. The pneumatic assembly includes a pressure holding cylinder 43 and a negative pressure pump 44, both of which are located on the top of the upper slide 13. The telescopic end of the pressure holding cylinder 43 passes through the upper slide 13 and the sealing assembly 2 to compress the calcareous sand sample placed inside the sample preparation assembly 3; a negative suction pipe 441 is installed on the negative pressure pump 44, and the other end of the negative suction pipe 441 passes through the upper slide 13 and is located inside the sealing assembly 2.

[0049] Gas-liquid supply structure 5: The gas-liquid supply structure 5 provides CO2 gas and degassing water to saturate the sample and discharges excess gas and liquid from the sealing assembly 2. The gas-liquid supply structure 5 includes a bracket 51 mounted on the base 11. The bracket 51 is equipped with a CO2 delivery tank 52 and a degassing water delivery tank 53. The gas outlet of the CO2 delivery tank 52 and the water outlet of the degassing water delivery tank 53 are connected by a confluence tee pipe 54. The confluence end of the confluence tee pipe 54 is connected to a flexible conduit 55, and the other end of the flexible conduit 55 is connected to the sample preparation assembly 3. A first valve 521 and a second valve 531 are respectively provided on the gas outlet of the CO2 delivery tank 52 and the water outlet of the degassing water delivery tank 53. The gas-liquid supply structure 5 includes a booster pump 56 mounted on the top of the top platform 15. A booster pipe 561 is installed on the booster pump 56 and is connected to the degassing water delivery tank 53. The CO2 delivery tank 52 is equipped with an inlet pipe 57, and an inlet valve 571 is provided on the inlet pipe 57. The gas-liquid supply structure 5 includes a drain hose 58 located at the bottom of the sealing assembly 2, and a drain valve 581 is provided on the drain hose 58.

[0050] The triaxial test calcium sand saturation device also includes a control panel 6, which is installed on the side wall of the base 11. The signal output terminal of the control panel 6 is connected to the signal receiving terminals of the lower slide hydraulic press 41, the upper slide hydraulic press 42, the pressure holding cylinder 43, and the negative pressure pump 44.

[0051] The following describes the process flow for the experiment of this utility model:

[0052] I. Sample Preparation

[0053] Three-valve assembly and installation: Assemble the three-valve diaphragm 32 completely, ensuring its sealing and integrity. The three-valve diaphragm 32 is a tubular structure formed by three arc-shaped plates. The rubber diaphragm 322 is evenly fitted into the interior of the three-valve diaphragm 32, making it fit tightly.

[0054] Calcareous sand sample loading: The calcareous sand sample is loaded into the three-lobed membrane 32 in 7 portions, and vibrated and compacted after each loading to ensure that the sample is uniformly filled and dense. By using the layered loading and vibration compaction method, voids or unevenness inside the sample are avoided, thus improving the sample quality.

[0055] Top Filter Paper and Filter Stone Covering: A layer of filter paper 34 is placed on top of the three-lobe membrane 32 to further ensure the purity and permeability of the sample. Finally, a filter stone 33 is placed on top to form the complete sample preparation assembly 3.

[0056] Installation of the sample preparation assembly: First, place a layer of filter stones 33 in the filter stone tank 311 to prevent calcareous sand particles from clogging the pores, while allowing liquids and gases to pass through. Cover the filter stones with a layer of filter paper 34. Insert the assembled three-lobe membrane 32 into the sample preparation assembly base 31, ensuring its accurate positioning.

[0057] II. Operation of the sealing assembly

[0058] Forming a seal: By controlling the switches on the control panel 6, the lower slide hydraulic press 41 and the upper slide hydraulic press 42 are operated until the cover 22 accurately covers the cover platform 21. When the cover 22 is on the cover platform 21, the retaining teeth 221 at the bottom of the cover 22 engage with the retaining groove 211 at the top of the cover platform 21. This structural design increases the contact area and improves the reliability of the seal.

[0059] Pressure holding block clamping: The pressure holding switch on the control panel 6 controls the extension of the telescopic end of the pressure holding cylinder 43. Finally, it presses down on the filter stone 33 above the sample preparation assembly 3. The function of the pressure holding cylinder 43 is to apply a certain pressure to the calcareous sand sample 7, ensuring that the calcareous sand sample 7 remains stable during the saturation process.

[0060] III. Gas Saturation Stage

[0061] Negative pressure environment formation: The negative pressure pump 44 is activated, continuously drawing air from inside the sealing assembly 2 through the negative suction pipe 441. As the internal air is continuously expelled, a relatively negative pressure environment gradually forms inside the sealing assembly 2. During this process, the internal pressure change is monitored in real time by a pressure gauge to ensure that the negative pressure reaches the set value.

[0062] Carbon dioxide gas introduction: Once the display shows that the internal pressure of the sealing assembly 2 has stabilized at a negative pressure state, CO2 gas is introduced into the CO2 delivery tank 52 through the inlet pipe 57. The first valve 521 on the confluence tee pipe 54 is opened, allowing CO2 gas to enter the sealing assembly 2 from the CO2 delivery tank 52 via the confluence tee pipe 54 and the flexible conduit 55, ultimately reaching the bottom of the sample. Because the interior is under negative pressure at this time, the CO2 gas will be evenly introduced into the voids inside the sample.

[0063] IV. Liquid Saturation Stage

[0064] Airless water injection: After the gas saturation reaches a certain level, the negative pressure pump 44 is turned off, and airless water is injected into the sealing assembly 2 through the airless water delivery tank 53. Under pressure, the airless water slowly rises from the bottom, gradually filling the voids inside the sample. As the airless water is continuously injected, carbon dioxide gas gradually dissolves in the water, further eliminating pores in the sample and making the sample more compact.

[0065] Pressure Holding Saturation: During the injection of degassing water, the pressure holding cylinder 43 continuously applies pressure to the sample to ensure its stability during liquid saturation. Simultaneously, a pressure gauge monitors internal pressure changes in real time, adjusting the injection volume and pressure of the degassing water as needed to ensure the sample reaches saturation under appropriate pressure holding conditions.

[0066] V. Drainage and Sample Removal

[0067] Excess airless water discharge: After the sample is saturated, first open the drain valve 581 on the drain hose 58 to discharge the excess airless water in the sealing assembly 2 through the drain hose 58. During the discharge process, pay attention to controlling the drainage speed to avoid sudden changes in the internal pressure of the sample due to excessive drainage, which could affect the integrity of the sample.

[0068] Device Reset and Sample Removal: After the sealing assembly 2 is completely emptied of air and water, the lower slide hydraulic press 41, upper slide hydraulic press 42, and pressure holding cylinder 43 are reset via the lifting switch and pressure holding switch on the control panel 6. At this time, the saturated calcareous sand sample 7 is removed from the sample preparation assembly 3, yielding a highly saturated sample for subsequent triaxial testing.

[0069] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A calcareous sand saturation device for triaxial testing, characterized by, The application relates to a sample preparation device. The support sample loading structure (1) comprises a base (11), two slide rods (12) are arranged on the top of the base (11) at intervals, an upper slide table (13) and a lower slide table (14) are arranged on the two slide rods (12) to slide, and a top table (15) is fixed between the top ends of the two slide rods (12). The sealing sample preparation structure comprises a sealing assembly (2), the sealing assembly (2) comprises a cover table (21) and a cover body (22), the cover table (21) is fixed on the top of the lower slide table (14), the cover body (22) is fixed on the bottom of the upper slide table (13), and a sample preparation assembly (3) is arranged in the sealing assembly (2). The hydraulic pneumatic structure (4) comprises a hydraulic assembly for controlling the lifting of the upper slide table (13) and the lower slide table (14) and a pneumatic assembly for pressure maintaining and air extraction of the sealing assembly (2). The gas-liquid supply structure (5) provides CO2 gas and gas-free water for sample saturation and discharges excess gas and liquid in the sealing assembly (2).

2. The calcareous sand saturator for triaxial testing of claim 1, wherein: The bottom of the cover body (22) is provided with a clamping tooth (221), and the top outer ring of the cover table (21) is provided with a clamping groove (211) matched with the clamping tooth (221).

3. The calcareous sand saturator for triaxial testing of claim 1, wherein: The sample preparation assembly (3) comprises a sample preparation assembly base (31), three membrane valves (32) are arranged on the sample preparation assembly base (31), fastening clamps (321) are arranged on the outer walls of the three membrane valves (32) at the upper and lower ends, a calcareous sand sample (7) is arranged in the three membrane valves (32), rubber membranes (322) are arranged on the inner walls of the three membrane valves (32), filter stones (33) are arranged on the top and bottom of the three membrane valves (32), filter papers (34) are arranged between the three membrane valves (32) and the filter stones (33), a filter stone groove (311) is formed in the top of the base (31), and the filter stones (33) and the filter papers (34) at the bottom of the three membrane valves (32) are arranged in the filter stone groove (311).

4. The calcareous sand saturator for triaxial testing of claim 1, wherein: The hydraulic assembly comprises a lower slide table hydraulic machine (41) and an upper slide table hydraulic machine (42), the lower slide table hydraulic machine (41) is arranged on the top of the base (11), and the telescopic end of the lower slide table hydraulic machine (41) is fixedly connected to the bottom of the lower slide table (14); the top of the top table (15) is provided with the upper slide table hydraulic machine (42), and the telescopic end of the upper slide table hydraulic machine (42) is fixedly connected to the top of the upper slide table (13) through the top table (15).

5. The calcareous sand saturator for triaxial testing of claim 1, wherein: The pneumatic assembly comprises a pressure maintaining cylinder (43) and a negative pressure pump (44), the pressure maintaining cylinder (43) and the negative pressure pump (44) are arranged on the top of the upper slide table (13), the telescopic end of the pressure maintaining cylinder (43) penetrates through the upper slide table (13) and the sealing assembly (2) and is used for extruding the calcareous sand sample arranged in the sample preparation assembly (3); the negative pressure pump (44) is provided with a negative suction pipe (441), and the other end of the negative suction pipe (441) penetrates through the upper slide table (13) and is arranged in the sealing assembly (2).

6. The calcareous sand saturator for triaxial testing of claim 1, wherein: The gas-liquid supply structure (5) comprises a support (51) arranged on the base (11), and the support (51) is provided with a CO2 delivery tank (52) and a still water delivery tank (53); the gas outlet end of the CO2 delivery tank (52) and the water outlet end of the still water delivery tank (53) are communicated with a converging tee pipe (54); the converging end of the converging tee pipe (54) is communicated with a soft conduit (55); the other end of the soft conduit (55) is communicated into the sample preparation assembly (3); and the gas outlet end of the CO2 delivery tank (52) and the water outlet end of the still water delivery tank (53) are respectively provided with a first valve (521) and a second valve (531).

7. The calcareous sand saturation device for triaxial testing of claim 6, wherein: The gas-liquid supply structure (5) comprises a booster air pump (56) arranged on the top of the top table (15), and the booster air pump (56) is provided with a booster pipe (561); and the booster pipe (561) is communicated with the still water delivery tank (53).

8. The calcareous sand saturator for triaxial testing of claim 6, wherein: The CO2 delivery tank (52) is provided with an air inlet pipe (57), and the air inlet pipe (57) is provided with an air inlet valve (571).

9. The calcareous sand saturator for triaxial testing of claim 1, wherein: The gas-liquid supply structure (5) comprises a drainage soft pipe (58) arranged on the bottom of the sealing assembly (2), and the drainage soft pipe (58) is provided with a drainage pipe valve (581).

10. The calcareous sand saturator for triaxial testing according to any one of claims 1 to 9, characterized in that: The triaxial test calcareous sand saturation device further comprises a control console (6) installed on the side wall of the base (11), and the signal output end of the control console (6) is communicated with the signal receiving end of the lower sliding table hydraulic machine (41), the upper sliding table hydraulic machine (42), the pressure maintaining air cylinder (43) and the negative pressure pump (44).

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