Method for manufacturing cohesive soil frozen saturated sample

Abstract

The invention discloses a method for manufacturing a cohesive soil frozen saturated sample. An organic glass sample tank is fixed between an upper baffle and a lower baffle; the upper permeable stone and the lower permeable stone can be tightly contacted with the upper surface and the lower surface of the cohesive soil sample by screwing and pressing the upper stud and the lower stud, so that the cohesive soil sample is tightly pressed; the extraction opening in the vacuum barrel cover is connected with the vacuum pump, so that the vacuum barrel can be subjected to vacuum extraction; the water inlet in the vacuum barrel cover is connected with the distilled water tank, so that the cohesive soil sample can be saturated; a cold source can be provided for quick freezing of a cohesive soil sample by winding a copper pipe on the side wall of the vacuum barrel and a copper pipe arranged in an S shape at the bottom and connecting the copper pipes with a constant-temperature cold bath device; through the arrangement of the side wall and the bottom heat preservation layer of the vacuum barrel, heat exchange between the interior of the vacuum barrel and the outside can be effectively prevented, and the heat insulation effect can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical testing, in particular to a method for preparing a frozen saturated sample of clay soil. Background Art

[0002] Frozen soil is a unique type of rock and soil characterized by two key characteristics: first, its temperature must not exceed zero degrees Celsius; second, ice must be present and the soil particles must be cemented by ice. These unique characteristics preclude the use of undisturbed clay samples in laboratory studies of frozen soil, necessitating the use of reshaped, frozen clay samples. The commonly used method for reshaping frozen saturated clay samples is to first use a sample preparation machine to produce the clay sample to the required test dimensions. The clay sample is then placed in a saturated mold and saturated by vacuum extraction. Once saturated, the clay sample is removed and frozen in situ at -30°C. Once frozen, the sample is removed for further research. However, frozen saturated clay samples prepared using this method exhibit uneven internal structure and moisture distribution, leading to significant errors in studies of frozen soil mechanics, thawing consolidation deformation, and high-temperature frozen soil properties.

[0003] The invention patent, publication number CN109085048A, discloses a non-cohesive soil freezing sample preparation device, which has the following problems:

[0004] 1. When using this equipment to freeze saturated samples, the temperature is low at -4°C and cannot be frozen quickly. As a result, water migration occurs inside the sample due to the temperature gradient, resulting in uneven internal structure and moisture content of the sample.

[0005] 2. When conducting subsequent related tests on frozen samples made with this equipment, the frozen samples need to be taken out, so the ambient temperature and the temperature of the related test equipment itself will have an impact on them.

[0006] 3. This equipment can only produce loose specimens: This is because when freezing saturated, non-viscous specimens, the frost heave deformation is small and the freezing force between them and the inner wall of the sample preparation chamber support tube is small, making the specimen easy to remove with the axial drive. However, when freezing saturated specimens made of cohesive soil, the frost heave deformation is large and the freezing force between them and the inner wall of the sample preparation chamber support tube is strong, making specimen removal more difficult. Even if removal is possible, the surface structure of the saturated, frozen specimen will be damaged.

[0007] 4. When the equipment is saturating the sample, moisture can only enter the sample through the pore channels on both sides of the sample preparation chamber base and the linear pore channels of the sample bottom cap. This does not ensure that the moisture inside the sample is saturated. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for preparing a frozen saturated sample of clay soil in order to address the technical defects in the prior art.

[0009] The technical solution adopted to achieve the purpose of the present invention is:

[0010] A method for preparing a frozen saturated sample of clay soil is accomplished by a preparation device, the preparation device comprising a sample fixing component, a vacuum saturation component, and a cooling component, the sample fixing component being located within the vacuum saturation component, and the cooling component being used to cool a vacuum barrel in the vacuum saturation component;

[0011] The sample fixing assembly includes an upper stud, an upper baffle, an organic glass sample jar with openings at both ends, an upper permeable stone, a lower permeable stone, a lower baffle and a lower stud. The upper permeable stone and the lower permeable stone are installed in the organic glass sample jar, and the outer edges of the upper permeable stone and the lower permeable stone fit the inner wall of the organic glass sample jar. The upper permeable stone and the lower permeable stone are used to clamp the clay soil sample. An upper pad is placed on the upper permeable stone. The upper stud passes through the upper baffle and enters the organic glass sample jar. The lower end of the upper stud contacts the upper pad. The upper permeable stone is pressed by pressing the upper pad. A lower pad is set between the upper and lower baffles, the lower stud passes through the lower baffle and enters the organic glass sample jar, the upper end of the lower stud contacts the lower pad, and the lower permeable stone is pressed by pressing the lower pad. The upper stud and the lower stud clamp the clay soil sample between the upper permeable stone and the lower permeable stone. The lower baffle is provided with a plurality of stainless steel screws along its circumference. The upper baffle is placed on the organic glass sample jar and is provided with screw holes. The stainless steel screws pass through the screw holes, and nuts are provided on the upper part of the stainless steel screws, and the organic glass sample jar is clamped between the upper baffle and the lower baffle through the nuts. The upper baffle and the lower baffle are both orifice plates.

[0012] The vacuum saturation assembly includes a vacuum barrel, a vacuum pump and a distilled water tank, the sample fixing assembly is placed in the vacuum barrel, a vacuum barrel cover is sealed on the vacuum barrel, an air extraction port and a water inlet are provided on the vacuum barrel cover, the air extraction port is connected to the vacuum pump through a silicone tube, an upper air stop clamp is provided on the silicone tube, the water inlet is connected to the distilled water tank through a silicone tube, an upper water stop clamp is provided on the silicone tube, a drain port is provided at the bottom of the vacuum barrel, the drain port is connected to the outside through a silicone tube, and a lower water stop clamp is provided on the silicone tube;

[0013] The cooling assembly includes a vacuum barrel side wall cooling assembly and a vacuum barrel bottom cooling assembly; the vacuum barrel side wall cooling assembly includes a side wall constant temperature cold bath device, a vacuum barrel side wall copper pipe is wound on the side wall of the vacuum barrel, and the vacuum barrel side wall copper pipe is connected to the side wall constant temperature cold bath device;

[0014] The vacuum barrel bottom cooling assembly includes a bottom constant temperature cold bath device, a vacuum barrel bottom copper pipe is arranged on the bottom of the vacuum barrel, and the vacuum barrel bottom copper pipe is connected to the bottom constant temperature cold bath device;

[0015] The method for preparing a frozen saturated sample comprises the following steps:

[0016] Step 1: Evenly apply vaseline on the inner wall of the organic glass sample jar. After the vaseline is applied, the clay sample is compacted layer by layer and placed into the organic glass sample jar. The sample is made into the size required for the test using a sample making machine.

[0017] Step 2: Install the lower stud on the lower baffle, screw the lower stud to an appropriate height, place a lower pad on the top of the lower stud, place a lower permeable stone on the lower pad, place the organic glass sample jar with the clay soil sample in step 1 on the lower baffle so that the lower part of the clay soil sample contacts the lower permeable stone, place the upper permeable stone on the upper surface of the clay soil sample, place the upper pad on the upper permeable stone, place the upper baffle on the organic glass sample jar, set multiple stainless steel screws along the circumference of the lower baffle, pass the stainless steel screws through the screw holes of the upper baffle, fix the organic glass sample jar between the upper baffle and the lower baffle by screwing the nuts, and screw the upper and lower studs at the same time so that the upper permeable stone is in full contact with the upper surface of the clay soil sample and the lower permeable stone is in full contact with the lower surface of the clay soil sample. After the assembly is completed, place it in a vacuum barrel and seal the vacuum barrel.

[0018] Step 3: Open the upper air stop clamp, close the upper water stop clamp and the lower water stop clamp, turn on the vacuum pump, and start vacuuming the vacuum barrel. After vacuuming, open the upper water stop clamp, and the distilled water in the distilled water tank enters the vacuum barrel through the silicone tube until the distilled water overflows the upper baffle. Turn off the vacuum pump, close the upper air stop clamp and the upper water stop clamp, and keep the clay soil sample immersed in distilled water.

[0019] Step 4: Open the lower water stop clamp to drain the water. After all the distilled water in the vacuum barrel is drained, set the temperature of the side wall constant temperature cold bath device and the bottom constant temperature cold bath device. The side wall constant temperature cold bath device cools the vacuum barrel through the copper tube on the side wall of the vacuum barrel, and the bottom constant temperature cold bath device cools the vacuum barrel through the copper tube at the bottom of the vacuum barrel to achieve rapid freezing of the clay soil sample.

[0020] In the above technical solution, a sealing ring is provided between the vacuum barrel and the vacuum barrel cover.

[0021] In the above technical solution, in step 2, the clay soil sample is assembled and placed in a vacuum barrel, and the vacuum barrel is sealed by covering it with a vacuum barrel cover.

[0022] In the above technical solution, a vacuum barrel side wall copper tube is vertically wound in an S shape on the outer wall of the vacuum barrel, a vacuum barrel bottom copper tube is arranged at the bottom of the vacuum barrel, and both ends of the vacuum barrel side wall copper tube are connected to the side wall constant temperature cold bath device through silicone tubes, and both ends of the vacuum barrel bottom copper tube are connected to the bottom constant temperature cold bath device through silicone tubes.

[0023] In the above technical solution, two drain ports are provided at the bottom of the vacuum barrel, namely the first drain port and the second drain port. The first drain port and the second drain port are connected to the outside world through silicone tubes respectively, and lower water stop clamps are provided on both silicone tubes.

[0024] In the above technical solution, the vacuum barrel insulation layer is wrapped around the copper tubes on the side walls of the vacuum barrel and the copper tubes on the bottom of the vacuum barrel.

[0025] In the above technical solution, the lower baffle is fixed on the stainless steel bracket.

[0026] In the above technical solution, a bottom support frame is installed at the bottom of the vacuum barrel.

[0027] In the above technical solution, three stainless steel screws are provided along the circumference of the lower baffle.

[0028] In the above technical solution, a vacuum bucket cover handle is provided on the vacuum bucket cover.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention fixes the organic glass sample jar between the upper baffle and the lower baffle by screwing the nut; the upper and lower studs are pressed and twisted to make the upper and lower permeable stones closely contact the upper and lower surfaces of the clay sample, thereby compacting the clay sample; the vacuum barrel can be vacuumed by connecting the air exhaust port on the vacuum barrel cover to the vacuum pump; the clay sample can be saturated by connecting the water inlet on the vacuum barrel cover to the distilled water tank; the clay sample can be quickly frozen by wrapping the copper tube around the side wall of the vacuum barrel and the copper tube arranged in an S shape at the bottom, and the two ends of the copper tube are connected to a constant temperature cold bath device to provide a cold source; the arrangement of the insulation layer on the side wall and the bottom of the vacuum barrel can effectively prevent heat exchange between the vacuum barrel and the outside world, and can achieve a heat insulation effect; the present invention can solve the test error caused by the uneven internal structure of the frozen clay sample, the device has good sealing performance, and the equipment is simple and convenient to operate.

[0031] 2. The device of the present invention is provided with an upper stud and a lower stud, which are used to suppress the deformation of the clay soil sample during the freezing process, that is, the deformation of the sample is prevented by applying pressure at both ends; at the same time, the present invention provides copper tubes on the barrel body and the bottom of the vacuum barrel for refrigeration, which can freeze the sample in three dimensions and freeze it quickly at -30°C; the synergistic effect of the above two methods makes the internal moisture of the prepared frozen saturated sample uniform, and the internal moisture is not easy to migrate during the freezing process.

[0032] 3. The vacuum barrel of the present invention is connected to the distilled water tank. By putting distilled water into the vacuum barrel, the clay soil sample is directly immersed in the distilled water for 24 hours, thereby ensuring the saturation of the sample.

[0033] 4. The present invention applies pressure to both ends of the frozen saturated sample through the upper stud and the lower stud to prevent deformation. At the same time, the organic glass sample jar provides pressure to the frozen saturated sample in the radial direction to prevent deformation. The two pressures work together to prevent the frozen saturated sample from being deformed. Moreover, when conducting subsequent tests on the frozen saturated sample, it is only necessary to take out the organic glass sample jar containing the frozen saturated sample. Therefore, it can ensure the radial deformation of the frozen saturated sample and solve the problem that the frozen saturated sample of clay soil is difficult to take out. Moreover, the frozen saturated sample will not be affected by the surrounding environment and the temperature of the relevant test equipment itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the overall structure of the device of Example 1.

[0035] Figure 2 This is a schematic structural diagram of the device of Example 1.

[0036] Figure 3 This is a cross-sectional view of the device of Example 1.

[0037] Figure 4 This is a schematic structural diagram of the device of Example 1.

[0038] Among them, 1.1: upper stud, 1.2: nut, 1.3: upper baffle, 1.4: organic glass sample jar, 1.5: upper spacer, 1.6: upper permeable stone, 1.7: lower permeable stone, 1.8: lower spacer, 1.9: lower baffle, 1.10: lower stud, 1.11: stainless steel bracket, 1.12: stainless steel screw, 2.1: vacuum barrel, 2.2: vacuum barrel cover, 2.3: vacuum pump, 2.4: distilled water tank, 2.5: bottom support frame, 2.6 : Sealing ring, 2.7: Air extraction port, 2.8: Water inlet, 2.9: Upper air stop clamp, 2.10: Upper water stop clamp, 2.11: Vacuum barrel lid handle, 2.12: First drain port, 2.13: Second drain port, 2.14: Lower water stop clamp, 3.1: Copper tube on the side wall of vacuum barrel, 3.2: Constant temperature cold bath device on the side wall, 3.3: Copper tube on the bottom of vacuum barrel, 3.4: Constant temperature cold bath device on the bottom, 3.5: Insulation layer of vacuum barrel, 4: Clay sample, 5: Silicone tube. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] like Figures 1-4 As shown, a method for preparing a frozen saturated sample of clay soil comprises the following steps:

[0042] Step 1, assemble the sample fixing assembly: evenly apply vaseline on the inner wall of the organic glass sample jar 1.4. The purpose is to enhance the sealing between the clay sample and the inner wall of the organic glass sample jar 1.4, and to enhance the lubricity between the clay sample and the inner wall of the organic glass sample jar 1.4. After the vaseline is applied, the clay sample 4 is layered and compacted and placed in the organic glass sample jar 1.4, and a sample making machine is used to make it into the size required for the test.

[0043] Step 2: Install the lower stud 1.10 on the lower baffle 1.9, screw the lower stud 1.10 to the appropriate height, place the lower pad 1.8 on the top of the lower stud 1.10, place the lower permeable stone 1.7 on the lower pad 1.8, place the organic glass sample jar 1.4 with the clay sample 4 in step 1 on the lower baffle 1.9, and install the lower baffle 1.9 on the stainless steel bracket 1.11. After the organic glass sample jar 1.4 is placed stably, place the upper permeable stone 1.6 on the upper surface of the clay sample 4, and place the upper pad on the upper permeable stone 1.6. Block 1.5, place the upper baffle 1.3 on the organic glass sample jar 1.4, and set three stainless steel screws 1.12 along the circumference of the lower baffle 1.9. The stainless steel screws 1.12 pass through the screw holes of the upper baffle 1.3. By tightening the nuts 1.2, the organic glass sample jar 1.4 is fixed between the upper baffle 1.3 and the lower baffle 1.9. At the same time, tighten the upper studs 1.1 and the lower studs 1.10 to ensure that the upper permeable stone 1.6 is in full contact with the upper surface of the clay soil sample 4 and the lower permeable stone 1.7 is in full contact with the lower surface of the clay soil sample 4.

[0044] Step 3. Place the sample fixing assembly into the vacuum barrel 2.1, cover the vacuum barrel cover 2.2, open the upper air stop clamp 2.9, close the upper water stop clamp 2.10 and the lower water stop clamp 2.14, turn on the vacuum pump 2.3, and start vacuum pumping the vacuum barrel 2.1. After vacuum pumping for 6 hours, open the upper water stop clamp 2.10, and the distilled water in the distilled water tank 2.4 enters the vacuum barrel 2.1 through the silicone tube 5 until the distilled water overflows the upper baffle 1.3. Turn off the vacuum pump 2.3, close the upper air stop clamp 2.9 and the upper water stop clamp 2.10, and soak the clay sample 4 in distilled water for 24 hours.

[0045] Step 4: Open the lower water stop clamp 2.14 to drain the water. After all the distilled water in the vacuum barrel 2.1 is drained, start freezing the clay soil sample 4. To prevent the migration of water inside the saturated clay soil sample 4 during the freezing process, a rapid freezing method is adopted. Therefore, the temperature of the side wall constant temperature cold bath device 3.2 and the bottom constant temperature cold bath device 3.4 is set to -30°C. Finally, after the clay soil sample 4 is completely frozen, it is taken out and relevant tests are carried out.

[0046] The method for preparing a frozen saturated sample of clay soil is completed by a preparation device, which includes a sample fixing component, a vacuum saturation component and a cooling component. The sample fixing component is located in the vacuum saturation component, and the cooling component is connected to the vacuum saturation component. The sample fixing component is used to fix the clay soil sample 4, and the vacuum saturation component is used to vacuum the clay soil sample 4 and inject distilled water to saturate the clay soil sample 4. The cooling component provides a cold source for the clay soil sample 4.

[0047] The sample fixing assembly includes an upper stud 1.1, a nut 1.2, an upper baffle 1.3, an organic glass sample jar 1.4 with openings at both ends, an upper pad 1.5, an upper permeable stone 1.6, a lower permeable stone 1.7, a lower pad 1.8, a lower baffle 1.9, a lower stud 1.10, a stainless steel bracket 1.11 and a stainless steel screw 1.12. The upper pad 1.5, the upper permeable stone 1.6, the lower permeable stone 1.7 and the lower pad 1.8 are arranged in sequence in the organic glass sample jar 1.4. The upper permeable stone 1.6 and the lower permeable stone 1.7 are used to clamp the clay sample 4. The outer edges of the upper permeable stone 1.6 and the lower permeable stone 1.7 are in contact with the inner wall of the organic glass sample jar 1.4. The upper baffle 1.3 is placed on the organic glass sample jar 1.4. The lower baffle 1.9 is arranged along its circumference. Three stainless steel screws 1.12, the stainless steel screw 1.12 passes through the screw hole of the upper baffle 1.3, and a nut 1.2 is set on the upper part thereof, and by screwing the nut 1.2, the organic glass sample jar 1.4 is fixed between the upper baffle 1.3 and the lower baffle 1.9, the upper baffle 1.3 and the lower baffle 1.9 are both orifice plates, the upper stud 1.1 passes through the upper baffle 1.3 and enters the organic glass sample jar 1.4, and its lower end contacts the upper pad 1.5, and the upper permeable stone 1.6 is pressed by pressing the upper pad 1.5, the lower stud 1.10 passes through the lower baffle 1.9 and enters the organic glass sample jar 1.4, and its upper end contacts the lower pad 1.8, and the lower permeable stone 1.7 is pressed by pressing the lower pad 1.8, and the lower baffle 1.9 is fixedly mounted on the stainless steel bracket 1.11.

[0048] The vacuum saturation assembly includes a vacuum barrel 2.1, a vacuum barrel cover 2.2, a vacuum pump 2.3, a distilled water tank 2.4 and a bottom support frame 2.5. The sample fixing assembly is placed in the vacuum barrel 2.1. The vacuum barrel cover 2.2 is sealed on the vacuum barrel 2.1, and a sealing ring 2.6 is provided between the two (further, in this embodiment, the vacuum barrel cover 2.2 and the vacuum barrel 2.1 are threadedly connected). An air extraction port 2.7 and a water inlet 2.8 are provided on the vacuum barrel cover 2.2. The air extraction port 2.7 is connected to the vacuum pump 2.3 through a silicone tube 5. An upper air stop clamp 2.9 is provided on the rubber hose 5, the water inlet 2.8 is connected to the distilled water tank 2.4 through the silicone tube 5, an upper water stop clamp 2.10 is provided on the silicone tube 5, a vacuum bucket cover handle 2.11 is provided on the vacuum bucket cover 2.2, a first drain port 2.12 and a second drain port 2.13 are opened at the bottom of the vacuum bucket 2.1, the first drain port 2.12 and the second drain port 2.13 are respectively connected to the outside world through the silicone tube 5, a lower water stop clamp 2.14 is provided on both silicone tubes 5, and the bottom support frame 2.5 is installed at the bottom of the vacuum bucket 2.1.

[0049] The cooling assembly includes a vacuum barrel side wall cooling assembly and a vacuum barrel bottom cooling assembly. The vacuum barrel side wall cooling assembly includes a vacuum barrel side wall copper tube 3.1 and a side wall constant temperature cold bath device 3.2. The vacuum barrel side wall copper tube 3.1 is vertically wound on the outer wall of the vacuum barrel 2.1 in an S shape, and both ends of the vacuum barrel side wall copper tube 3.1 are connected to the side wall constant temperature cold bath device 3.2 through a silicone tube 5; the vacuum barrel bottom cooling assembly includes a vacuum barrel bottom copper tube 3.3 and a bottom constant temperature cold bath device 3.4. The vacuum barrel bottom copper tube 3.3 is arranged at the bottom of the vacuum barrel 2.1, and both ends of the vacuum barrel bottom copper tube 3.3 are connected to the bottom constant temperature cold bath device 3.4 through a silicone tube 5; a vacuum barrel insulation layer 3.5 is wrapped around the vacuum barrel side wall copper tube 3.1 and the vacuum barrel bottom copper tube 3.3.

[0050] Furthermore, the upper water stop clamps 2.9, 2.10 and the lower water stop clamp 2.14 can be switched on and off by electrical control.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a frozen saturated sample of clay soil, characterized in that: The manufacturing device is completed by the manufacturing device, which includes a sample fixing component, a vacuum saturation component and a cooling component. The sample fixing component is located in the vacuum saturation component, and the cooling component is used to cool the vacuum barrel in the vacuum saturation component; The sample fixing assembly includes an upper stud, an upper baffle, an organic glass sample jar with openings at both ends, an upper permeable stone, a lower permeable stone, a lower baffle and a lower stud. The upper permeable stone and the lower permeable stone are installed in the organic glass sample jar, and the outer edges of the upper permeable stone and the lower permeable stone fit the inner wall of the organic glass sample jar. The upper permeable stone and the lower permeable stone are used to clamp the clay soil sample. An upper pad is placed on the upper permeable stone. The upper stud passes through the upper baffle and enters the organic glass sample jar. The lower end of the upper stud contacts the upper pad. The upper permeable stone is pressed by pressing the upper pad. A lower pad is set between the upper and lower baffles, the lower stud passes through the lower baffle and enters the organic glass sample jar, the upper end of the lower stud contacts the lower pad, and the lower permeable stone is pressed by pressing the lower pad. The upper stud and the lower stud clamp the clay soil sample between the upper permeable stone and the lower permeable stone. The lower baffle is provided with a plurality of stainless steel screws along its circumference. The upper baffle is placed on the organic glass sample jar and is provided with screw holes. The stainless steel screws pass through the screw holes, and nuts are provided on the upper part of the stainless steel screws, and the organic glass sample jar is clamped between the upper baffle and the lower baffle through the nuts. The upper baffle and the lower baffle are both orifice plates. The vacuum saturation assembly includes a vacuum barrel, a vacuum pump and a distilled water tank, the sample fixing assembly is placed in the vacuum barrel, a vacuum barrel cover is sealed on the vacuum barrel, an air extraction port and a water inlet are provided on the vacuum barrel cover, the air extraction port is connected to the vacuum pump through a silicone tube, an upper air stop clamp is provided on the silicone tube, the water inlet is connected to the distilled water tank through a silicone tube, an upper water stop clamp is provided on the silicone tube, a drain port is provided at the bottom of the vacuum barrel, the drain port is connected to the outside through a silicone tube, and a lower water stop clamp is provided on the silicone tube; The cooling assembly includes a vacuum barrel side wall cooling assembly and a vacuum barrel bottom cooling assembly; the vacuum barrel side wall cooling assembly includes a side wall constant temperature cold bath device, a vacuum barrel side wall copper tube is wound on the side wall of the vacuum barrel, and the vacuum barrel side wall copper tube is connected to the side wall constant temperature cold bath device; The vacuum barrel bottom cooling assembly includes a bottom constant temperature cold bath device, a vacuum barrel bottom copper pipe is arranged on the bottom of the vacuum barrel, and the vacuum barrel bottom copper pipe is connected to the bottom constant temperature cold bath device; A sealing ring is provided between the vacuum barrel and the vacuum barrel cover; a vacuum barrel side wall copper tube is vertically wound in an S-shape on the outer wall of the vacuum barrel, and a vacuum barrel bottom copper tube is arranged at the bottom of the vacuum barrel. Both ends of the vacuum barrel side wall copper tube are connected to the side wall constant temperature cold bath device through silicone tubes, and both ends of the vacuum barrel bottom copper tube are connected to the bottom constant temperature cold bath device through silicone tubes; a vacuum barrel insulation layer is wrapped around the vacuum barrel side wall copper tube and the vacuum barrel bottom copper tube; The method for preparing a frozen saturated clay soil sample comprises the following steps: Step 1: Evenly apply vaseline on the inner wall of the organic glass sample jar. After the vaseline is applied, the clay sample is compacted layer by layer and placed into the organic glass sample jar. The sample is made into the size required for the test using a sample making machine. Step 2: Install the lower stud on the lower baffle, screw the lower stud to an appropriate height, place a lower pad on the top of the lower stud, place a lower permeable stone on the lower pad, place the organic glass sample jar with the clay soil sample in step 1 on the lower baffle, place the upper permeable stone on the upper surface of the clay soil sample, place the upper pad on the upper permeable stone, place the upper baffle on the organic glass sample jar, set multiple stainless steel screws along the circumference of the lower baffle, pass the stainless steel screws through the screw holes of the upper baffle, fix the organic glass sample jar between the upper baffle and the lower baffle by screwing the nuts, and screw the upper and lower studs at the same time so that the upper permeable stone is in full contact with the upper surface of the clay soil sample and the lower permeable stone is in full contact with the lower surface of the clay soil sample. After the assembly is completed, place it in a vacuum barrel and seal the vacuum barrel. Step 3: Open the upper air stop clamp, close the upper water stop clamp and the lower water stop clamp, turn on the vacuum pump, and start vacuum pumping the vacuum barrel. After vacuum pumping, open the upper water stop clamp, and the distilled water in the distilled water tank enters the vacuum barrel through the silicone tube until the distilled water overflows the upper baffle. Turn off the vacuum pump, close the upper air stop clamp and the upper water stop clamp, and keep the clay soil sample immersed in distilled water. Step 4: Open the lower water stop clamp to drain the water. After all the distilled water in the vacuum barrel is drained, set the temperature of the side wall constant temperature cold bath device and the bottom constant temperature cold bath device to -30°C. The side wall constant temperature cold bath device cools the vacuum barrel through the copper tube on the side wall of the vacuum barrel, and the bottom constant temperature cold bath device cools the vacuum barrel through the copper tube on the bottom of the vacuum barrel to achieve rapid freezing of the clay soil sample.

2. The method according to claim 1, characterized in that In step 2, the clay soil sample is assembled and placed in a vacuum barrel, and the vacuum barrel is sealed by covering it with a vacuum barrel cover.

3. The method according to claim 1, characterized in that Two drain ports are provided at the bottom of the vacuum barrel, namely a first drain port and a second drain port. The first drain port and the second drain port are connected to the outside world through silicone tubes respectively, and lower water stop clamps are provided on both silicone tubes.

4. The method according to claim 1, wherein The lower baffle is fixed on the stainless steel bracket.

5. The method according to claim 1, wherein Install the bottom support frame on the bottom of the vacuum tank.

6. The method according to claim 1, characterized in that The lower baffle is provided with three stainless steel screws along its circumference.

7. The method according to claim 1, characterized in that A vacuum bucket cover handle is provided on the vacuum bucket cover.

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