Device for manufacturing frozen sand sample with high ice content and non-uniform particle size and use method

Abstract

The invention relates to a device for manufacturing a frozen sand sample with high ice content and non-uniform particle size and a use method. The device comprises a mold assembly, a rotary driving assembly, a mold fixing assembly and a uniform vibration assembly, the method comprises the following steps: preparing a dry sand sample and ice particles, and freezing in a refrigeration house; uniformly mixing the dry sand sample and the ice particles according to a certain mass ratio, and loading the mixture into a mold assembly; the mold assembly is put into a glass jar containing ice water to be supplemented with water, and the glass jar is rapidly vacuumized; after water replenishing is completed, a water stop valve on the mold assembly is closed and installed on the device, the device is put into a refrigeration house to be frozen after being powered on, and after freezing is completed, the sample is disassembled to obtain a high-ice-content frozen sand sample; according to the invention, a dry sand sample and ice particles are uniformly mixed and then loaded into a mold assembly, water is supplemented by using a vacuum saturation method, and when the sand particles, the ice particles and water molecules in the sample are frozen, spatial uniform distribution of a three-phase medium is realized and pores are reduced through a vibration-rotation coupling effect.

Description

Technical Field

[0001] The invention relates to the technical field of frozen soil sample preparation, and in particular to a device and a method for preparing frozen sandy soil samples with high ice content and uneven particle size. Background Art

[0002] In recent years, with the rapid growth of the global economy and the intensification of resource consumption, the forests, minerals, land, tourism and other resources in cold regions have gradually attracted widespread attention. In the future, the construction scenarios of cold region projects will increase. Whether it is the early construction or the later operation of cold region projects, it is inevitable to involve the problem of high ice content frozen soil. Therefore, understanding the mechanical properties, thermophysical behavior and changing laws of high ice content frozen soil has become a key factor in ensuring the safety and stability of engineering structures.

[0003] The first step in studying high-ice-content frozen soil is to restore high-ice-content frozen soil samples, which provides a basis for subsequent research. High-ice-content frozen soil refers to frozen soil with an ice content of more than 25% by volume. Compared with conventional frozen soil, its most notable feature is its higher ice content. Therefore, a series of technical difficulties are inevitably encountered during the preparation process.

[0004] In the natural environment, the soil in many areas forms a thick layer of ice in cold seasons, or produces frozen soil with a high ice content under the action of groundwater. These phenomena directly affect the strength and deformation properties of frozen soil. When studying the impact of high ice content frozen soil on soil structure, different soil types (such as sandy soil, clay, etc.) will have different effects under low temperature conditions. Therefore, in addition to the need to study high ice content frozen clay, high ice content frozen sand is also crucial.

[0005] At present, the method of making frozen sand with high ice content is relatively mature. It is usually to mix soil particles, ice particles and unfrozen water and directly press them into samples. However, when the pressed sample is frozen, the sample will contain unfrozen water and small sand particles due to the uneven particle size distribution of sand. Since small sand particles tend to accumulate downward in water, it is difficult to ensure that the three-phase medium space inside the sample is evenly distributed and saturated without pores.

[0006] Therefore, it is particularly important to invent a device and a method for preparing frozen sand samples with high ice content and uneven particle size, so as to achieve the purpose of preparing relatively uniform and saturated frozen sand samples with high ice content. Summary of the invention

[0007] The present invention aims to solve the problems of insufficient sample uniformity and saturation existing in the prior art in the method of preparing frozen sandy soil samples with high ice content, and provides a device and a use method for making frozen sandy soil samples with high ice content and uneven particle sizes. This device and method can prepare frozen soil samples with high ice content that meet the test requirements under laboratory conditions, and have the characteristics of simple operation, strong practicability and high reliability.

[0008] To achieve the above object, the technical solution of the present invention is realized as follows:

[0009] A device for making frozen sandy soil samples with high ice content and uneven particle sizes, characterized in that the device is composed of a mold assembly, a rotary drive assembly, a mold fixing assembly and a uniform vibration assembly. The mold assembly is located between the rotary drive assembly and the mold fixing assembly. The rotary drive assembly and the mold fixing assembly are connected by a guide rail. The uniform vibration assembly is located below the rotary drive assembly.

[0010] Specifically, the mold assembly includes: a left outer shell, a permeable plate, a permeable stone, an iron mold, a right outer shell and a clamp. The permeable plate, the permeable stone and the iron mold are sequentially placed in the left outer shell, and the right outer shell is closed with the left outer shell. After the right outer shell and the left outer shell are closed, the limit semi-cylinders on the outer shells are aligned in pairs, and fixed with two clamps. Among them, a water replenishing cavity and a water guiding hole are arranged inside the permeable plate, which are communicated with the water replenishing holes on the water replenishing pipe and the permeable stone respectively. The right square column on the right outer shell of the mold assembly is inserted into the right square hole bearing in the mold fixing assembly, and the left square column on the left outer shell is inserted into the left square hole bearing in the rotary drive assembly. Among them, a spring is installed inside the right square hole bearing.

[0011] Preferably, a sealing rubber ring is arranged between the left outer shell and the right outer shell of the mold assembly.

[0012] The bottom of the rotary drive assembly is provided with a concave guide rail, and the bottom of the mold fixing assembly is provided with a convex slider. Among them, two through holes are arranged at the bottom of the concave guide rail, and two screw holes are arranged at the same position of the through holes at the bottom of the convex slider. After the through holes and the screw holes are aligned in pairs, they are fixed with screws.

[0013] Specifically, a servo rotary motor is installed inside the rotary drive assembly, and the servo rotary motor is connected to the left square hole bearing in the rotary drive assembly.

[0014] Specifically, four connecting seats and a uniform vibration assembly are installed below the rotary drive assembly. A linear vibration motor is installed inside the uniform vibration assembly. The four connecting seats below the rotary drive assembly are connected to the four connecting seats above the bottom plate through four springs respectively.

[0015] A method for using a device to produce frozen sandy soil specimens with a high ice content and uneven particle sizes, based on the device for producing frozen sandy soil specimens with a high ice content and uneven particle sizes described above, the method includes:

[0016] In the first step, prepare dry sand samples and place them in a cold storage for freezing;

[0017] In the second step, prepare ice particles;

[0018] In the third step, uniformly mix the dry sand samples and ice particles according to a certain mass ratio and load them into the mold assembly;

[0019] In the fourth step, place the mold assembly into a glass cylinder filled with ice water for water replenishment, and quickly evacuate the glass cylinder;

[0020] In the fifth step, after the water replenishment is completed, close the water stop valve on the mold assembly and install the mold assembly on the device. After the device is powered on, place it in the cold storage for freezing;

[0021] In the sixth step, after the freezing is completed, disassemble the sample to obtain a frozen sandy soil specimen with a high ice content.

[0022] Preferably, after the freezing is completed, disassemble the sample to obtain a frozen sandy soil specimen with a high ice content, and determine the final ice content w of the specimen: m1 is the total mass of the dry sand sample and ice particles, m2 is the mass of the frozen soil specimen, and ν is the mass ratio of the dry sand sample and ice particles.

[0023] Preferably, the method for obtaining the ice particles is: place pure water in the cold storage for freezing for 24 hours, then take out the ice cubes and shave them into small particle ice with a professional ice shaver, and then pass through a sieve with a diameter of 2 mm to remove large-sized ice particles to obtain ice particles with the same particle size range as the sandy soil particles.

[0024] Preferably, after the dry sand samples and ice particles are stirred evenly, they are loaded into the mold assembly by the method of one-time compaction, and the specimen production process is carried out in a cold storage with the cold storage door open, and the freezing time of the specimen after the water replenishment is completed is 24 hours.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] In the present invention, dry sand samples and ice particles are mixed evenly and then loaded into the mold assembly, initially ensuring the uniform distribution of the ice and soil phases in the sample. The vacuum saturation method is used to replenish water in the sample, reducing the internal pores of the sample and ensuring its saturation. Then, when the mold assembly is installed on the device and placed in the cold storage for freezing, under the coordinated operation of the rotary drive assembly and the uniform vibration assembly, through the vibration-rotation coupling effect, the sand particles, ice particles, and water molecules in the frozen soil sample in the mold assembly undergo random motion, further reducing the problems of uneven distribution of the three-phase medium and the existence of pores inside the sample while ensuring that the sample is frozen from the outside to the inside. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings illustrate exemplary embodiments of the present invention and are used, together with the description thereof, to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention, and the drawings are included in this specification and form a part of this specification, and do not constitute a limitation on the embodiments of the present invention.

[0028] Figure 1 is a schematic structural diagram of the device for fabricating a frozen sand sample with a high ice content and uneven particle sizes according to the present invention;

[0029] Figure 2 is a side view of the structure of the device for fabricating a frozen sand sample with a high ice content and uneven particle sizes according to the present invention;

[0030] Figure 3 is a schematic structural diagram of each component of the mold assembly according to the present invention;

[0031] Figure 4 is a schematic structural diagram of the water-permeable plate according to the present invention;

[0032] Reference numerals: 1 - mold assembly, 2 - rotary drive assembly, 3 - mold fixing assembly, 4 - uniform vibration assembly, 5 - right square-hole bearing, 6 - left square-hole bearing, 7 - connecting seat, 8 - spring, 9 - connecting seat, 10 - bottom plate, 11 - left outer shell, 12 - right outer shell, 13 - water-permeable plate, 14 - water-permeable stone, 15 - iron mold, 16 - limiting semi-cylinder, 17 - clamp, 18 - right square column, 19 - left square column, 20 - water supply pipe, 21 - water stop valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other

[0034] All embodiments fall within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] As Figure 1 shown, a device for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes is provided. The device consists of four parts: a mold assembly 1, a rotary drive assembly 2, a mold fixing assembly 3, and a uniform vibration assembly 4. The mold assembly 1 is located between the rotary drive assembly 2 and the mold fixing assembly 3. The rotary drive assembly 2 and the mold fixing assembly 3 are connected by a guide rail. The uniform vibration assembly 4 is located below the rotary drive assembly 2.

[0037] The mold assembly 1 includes: a left outer shell 11, a water permeable plate 13, a water permeable stone 14, an iron mold 15, a right outer shell 12, and a clamp 17. The water permeable plate 13, the water permeable stone 14, and the iron mold 15 are sequentially placed into the left outer shell 11, and the right outer shell 12 is used to close the left outer shell 11. After the right outer shell 12 and the left outer shell 11 are closed, the limit semi-cylinders 16 on the outer shells are aligned in pairs and fixed with two clamps 17. A water replenishing cavity and water guiding holes are provided inside the water permeable plate 13, which are respectively communicated with the water replenishing holes on the water replenishing pipe 20 and the water permeable stone 14. The right square column 18 on the right outer shell 12 of the mold assembly 1 is inserted into the right square hole bearing 5 in the mold fixing assembly 3, and the left square column 19 on the left outer shell 11 is inserted into the left square hole bearing 6 in the rotary drive assembly 2. A spring is installed inside the right square hole bearing 5.

[0038] As Figure 3 shown, the iron mold 15 is mainly used for filling the ice-soil mixture. All components in the mold assembly 1, except the iron mold 15 and the water permeable stone 14, are made of epoxy resin.

[0039] As Figure 4 shown, a water replenishing cavity and water guiding holes are provided inside the water permeable plate 13. Through the water replenishing cavity and water guiding holes of the water permeable plate 13, the liquid water can be dispersed once, and then the liquid water is dispersed a second time through the water permeable stone 14, so that when replenishing water, the ice-soil mixture can be evenly penetrated.

[0040] The bottom of the rotary drive assembly 2 is provided with a concave guide rail, and the bottom of the mold fixing assembly 3 is provided with a convex slider. Two through holes are provided at the bottom of the concave guide rail, and two screw holes are provided at the same positions of the through holes at the bottom of the convex slider. After the through holes and the screw holes are aligned in pairs, they are fixed with screws.

[0041] When installing the mold assembly 1 onto the device, insert the right square column 18 on the right housing 12 into the right square-hole bearing 5 in the mold fixing assembly 3. There is a spring inside the right square-hole bearing 5. Press the mold assembly 1 forcefully to insert the right square column 18 on the right housing 12 completely into the right square-hole bearing 5. At the same time, push the convex slider at the bottom of the mold fixing assembly 3 into the concave guide rail at the bottom of the rotary drive assembly 2, and then release the mold assembly 1. The spring inside the right square-hole bearing 5 is unloaded, and then the left square column 19 on the left housing 11 is pushed into the left square-hole bearing 6 in the rotary drive assembly 2 to complete the installation of the mold assembly 1.

[0042] After completing the installation of the mold assembly 1, the convex slider at the bottom of the mold fixing assembly 3 is completely pushed into the concave guide rail at the bottom of the rotary drive assembly 2. At this time, the screw holes at the bottom of the convex slider and the through holes at the bottom of the concave guide rail are aligned in pairs. Use two screws to connect the mold fixing assembly 3 and the rotary drive assembly 2 to further ensure the stable operation of the device.

[0043] A servo rotary motor is installed inside the rotary drive assembly 2, and the servo rotary motor is connected to the left square-hole bearing 6 in the rotary drive assembly 2.

[0044] Since the left square-hole bearing 6 and the left square column 19 conduct torque through a matching shape, when the servo rotary motor works, it drives the left square-hole bearing 6 to rotate, and then indirectly drives the mold assembly 1 to rotate, and the rotation speed should not be too fast.

[0045] Four connecting seats 7 and a uniform vibration assembly 4 are installed below the rotary drive assembly 2. A linear vibration motor is installed inside the uniform vibration assembly 4. The four connecting seats 7 below the rotary drive assembly 2 are respectively connected to the four connecting seats 9 above the bottom plate 10 through four springs 8.

[0046] The uniform vibration assembly 4 and the rotary drive assembly 2 achieve multi-dimensional homogenization treatment of the frozen soil specimen through a collaborative working mechanism. The linear vibration motor built into the uniform vibration assembly 4 effectively eliminates the air bubbles inside the specimen through high-frequency micro-amplitude vibration, but various particles inside the specimen are prone to accumulate downward, forming a situation where it is dense at the bottom and sparse at the top. The servo rotary motor built into the rotary drive assembly 2 uses the left square column 19 of the mold assembly 1 as the rotation axis to drive the specimen to perform a ±180° reciprocating rotation motion. This composite motion mechanism overcomes the phenomenon of particle longitudinal segregation (i.e., the structural defect of the specimen being dense at the bottom and loose at the top) caused by gravity sedimentation in the traditional vibration process through the vibration-rotation coupling effect, and realizes the spatial uniform distribution of the three-phase medium (sand particles, ice particles, unfrozen water).

[0047] A sealing rubber ring is provided between the left housing 11 and the right housing 12 in the mold assembly 1 to prevent the mold assembly 1 from leaking water to the outside when the device is working.

[0048] Example 2

[0049] This embodiment provides a method for using a device for producing a frozen sandy soil specimen with a high ice content and uneven particle sizes. The method includes:

[0050] First step, prepare dry sand samples and place them in a cold storage for freezing.

[0051] Second step, prepare ice particles. The method for obtaining ice particles is as follows: Put pure water into the cold storage and freeze it for 24 hours, then take out the ice cubes and shave them into small particle ice with a professional ice shaver, and then pass them through a sieve with a diameter of 2 mm to remove large-sized ice particles, obtaining ice particles with the same particle size range as the sandy soil particles.

[0052] Third step, uniformly mix the dry sand samples and ice particles according to a certain mass ratio and load them into the mold assembly; The uniform mixing is achieved by an electric stirrer, avoiding the problem of insufficient manual stirring. After stirring the dry sand samples and ice particles evenly, they are loaded into the mold assembly by the method of single compaction.

[0053] Fourth step, place the mold assembly into a glass cylinder filled with ice water for water replenishment, and quickly evacuate the glass cylinder; The ice water in the glass cylinder should completely submerge the mold assembly, and the mold assembly can be taken out after a short water replenishment.

[0054] Fifth step, after the water replenishment is completed, close the water stop valve on the mold assembly and install the mold assembly on the device. After the device is powered on, it is placed in the cold storage for freezing.

[0055] Sixth step, after the freezing is completed, disassemble the sample to obtain a frozen sandy soil specimen with a high ice content.

[0056] After the freezing is completed, disassemble the sample to obtain a frozen sandy soil specimen with a high ice content, and determine the final ice content w of the specimen: m1 is the total mass of the dry sand samples and ice particles, m2 is the mass of the frozen soil specimen, and ν is the mass ratio of the dry sand samples and ice particles.

[0057] The specimen production process needs to be carried out in a cold storage with the cold storage door open. The freezing time of the specimen after the water replenishment is completed is 24 hours.

[0058] In the description of this specification, the descriptions referring to terms such as "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / ways or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments / ways or examples described in this specification and the features of different embodiments / ways or examples.

[0059] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0060] Those skilled in the art should understand that the above embodiments are only for clearly explaining the present invention and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications can be made based on the above invention, and these changes or modifications are still within the scope of the present invention.

Claims

1. An apparatus for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes, characterized in that, The device is composed of four parts: a mold assembly (1), a rotary drive assembly (2), a mold fixing assembly (3), and a uniform vibration assembly (4). The mold assembly (1) is located between the rotary drive assembly (2) and the mold fixing assembly (3). The rotary drive assembly (2) and the mold fixing assembly (3) are connected by a guide rail. The uniform vibration assembly (4) is located below the rotary drive assembly (2).

2. The device for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes according to claim 1, wherein The mold assembly (1) includes: a left outer shell (11), a water permeable plate (13), a water permeable stone (14), an iron mold (15), a right outer shell (12), and a clamp (17). The water permeable plate (13), the water permeable stone (14), and the iron mold (15) are sequentially placed into the left outer shell (11), and the right outer shell (12) is used to close the left outer shell (11). After the right outer shell (12) and the left outer shell (11) are closed, the limit semi-cylinders (16) on the outer shells are aligned in pairs, and fixed with two clamps (17). Among them, a water replenishing cavity and water guiding holes are arranged inside the water permeable plate (13), which are respectively communicated with the water replenishing holes on the water replenishing pipe (20) and the water permeable stone (14). The right square column (18) on the right outer shell (12) of the mold assembly (1) is inserted into the right square hole bearing (5) in the mold fixing assembly (3), and the left square column (19) on the left outer shell (11) is inserted into the left square hole bearing (6) in the rotary drive assembly (2). Among them, a spring is installed inside the right square hole bearing (5).

3. The device for making a frozen sandy soil specimen with high ice content and uneven particle sizes according to claim 2, wherein a sealing rubber ring is arranged between the left outer shell (11) and the right outer shell (12) of the mold assembly (1).

4. The device for fabricating a frozen sandy soil specimen with high ice content and non-uniform particle sizes according to claim 1, characterized in that, A concave guide rail is provided at the bottom of the rotary drive assembly (2), and a convex slider is provided at the bottom of the mold fixing assembly (3). Among them, two through holes are provided at the bottom of the concave guide rail, and two screw holes are provided at the same positions of the through holes at the bottom of the convex slider. After the through holes and the screw holes are aligned in pairs, they are fixed with screws.

5. The device for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes according to claim 1, characterized in that, A servo rotary motor is installed inside the rotary drive assembly (2), and the servo rotary motor is connected to the left square hole bearing (6) in the rotary drive assembly (2).

6. The device for fabricating a frozen sandy soil specimen with a high ice content and uneven particle sizes according to claim 1, wherein Four connecting seats (7) and a uniform vibration assembly (4) are installed below the rotary drive assembly (2). Among them, a linear vibration motor is installed inside the uniform vibration assembly (4). The four connecting seats (7) below the rotary drive assembly (2) are respectively connected to the four connecting seats (9) above the bottom plate (10) through four springs (8).

7. A method for using a device for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes, characterized in that, Based on the device for making a frozen sandy soil specimen with high ice content and uneven particle sizes according to any one of claims 1-6, the method includes: The first step is to prepare dry sand samples and freeze them in a cold storage. The second step is to prepare ice particles. The third step is to uniformly mix the dry sand samples and the ice particles according to a certain mass ratio and load them into the mold assembly. The fourth step is to place the mold assembly into a glass cylinder filled with ice water for water replenishment, and quickly evacuate the glass cylinder. In the fifth step, after the water replenishment is completed, close the water stop valve on the mold assembly and install the mold assembly onto the device. After the device is powered on, place it in a cold storage for freezing; In the sixth step, after the freezing is completed, disassemble the sample to obtain a frozen sandy soil sample with a high ice content.

8. The method of using the device for fabricating a frozen sandy soil specimen with high ice content and non-uniform particle sizes according to claim 7, characterized in that, After the freezing is completed, the frozen sandy soil specimen with a high ice content is obtained by disassembling the sample, and the final ice content w of the specimen is determined: m1 is the total mass of the dry sand sample and ice particles, m2 is the mass of the frozen soil specimen, and ν is the mass ratio of the dry sand sample to ice particles.

9. The method of using the device for fabricating a frozen sandy soil specimen with a high ice content and non-uniform particle sizes according to claim 7, characterized in that, The method for obtaining ice particles is as follows: Place pure water in a cold storage for 24 hours and then take out the ice cubes. Use a professional ice shaver to shave them into small ice particles, and then pass them through a sieve with a diameter of 2 mm to remove large-sized ice particles, obtaining ice particles with the same particle size range as the sandy soil particles.

10. The method for using the device for producing a frozen sandy soil sample with a high ice content and non-uniform particle sizes according to claim 7, characterized in that, After uniformly mixing the dry sand sample and the ice particles, use the method of single compaction to load them into the mold assembly, and the sample preparation process is carried out in a cold storage with the cold storage door open. The freezing time of the sample after the water replenishment is completed is 24 hours.

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