A method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing

Abstract

The present invention proposes a method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing, which belongs to the technical field of simulated lunar soil preparation. It solves the problem that in the freezing process of water ice in the previous profile sample, the freezing rate of the sample boundary will be stronger than that of the sample interior, causing the sample boundary temperature to be lower than the sample center. Due to the principle of cold end migration of water, the water inside the sample will migrate to the surroundings, causing the water content of the sample boundary to be higher than that of the sample center. The water content of the entire sample is not uniform, and the strength and hardness of samples with different water contents are also different. As a result, the stress, drilling power and water content of each drill during the sample drilling process in the later test cannot be unified, and the variables cannot be controlled, resulting in the drilling test data obtained in the later stage having no reference value. Through the sample preparation process of the present invention, the ice is frozen and crushed separately and then evenly mixed with the dry and cooled simulated lunar soil sample, so that the water content of each part of the entire sample is relatively uniform and reaches a controllable level.

Description

Technical Field

[0001] The present invention belongs to the technical field of simulated lunar soil preparation, and in particular relates to a method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing. Background Art

[0002] In the past, during the freezing process of water ice in cross-section samples, the freezing rate at the sample boundary would be stronger than that inside the sample, causing the sample boundary temperature to be lower than the sample center. Due to the principle of cold-end migration of water, the water inside the sample would migrate to the surrounding area, causing the water content at the sample boundary to be higher than that in the sample center. The water content of the entire sample was uneven, and the strength and hardness of samples with different water contents were also different. As a result, the stress, drilling power and water content per drilled during the sample drilling process in later tests could not be unified, and the variables could not be controlled, resulting in the drilling test data obtained later having no reference value. Summary of the Invention

[0003] In view of this, in order to solve the problems mentioned in the above background technology, the present invention proposes a method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing, which is mainly used for the large-scale preparation of simulated lunar soil water ice profile samples in the field of deep space exploration and engineering tests.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing, specifically comprising the following steps:

[0005] Step S1: Preparation of dry soil raw materials: selecting the components and particle shapes of the raw materials, mixing the selected particles of different components in a certain proportion, and drying the mixed raw materials;

[0006] Step S2: pre-cooling each preparation device before preparation;

[0007] Step S3: Calculating the initial moisture content;

[0008] Step S4: ice particle preparation: quantitatively prepare water, freeze it, and then crush it into small particles for later use;

[0009] Step S5: mixing the ice particles with the dried soil raw material;

[0010] Step S6: presetting the dense attached barrel stress sensor in a low temperature environment;

[0011] Step S7: compacting the mixed sample layer by layer in a low temperature environment;

[0012] Step S8: Presetting the temperature sensor of the compacting barrel;

[0013] Step S9: Maintaining the sample under confining pressure for a long time under ultra-low temperature conditions.

[0014] Furthermore, in step S1, plagioclase and basalt are selected as raw materials for preparing simulated lunar soil based on the mineral composition of the polar lunar soil, and the particle size of the polar lunar soil is less than 1 mm.

[0015] Furthermore, in step S1, the mass of the sample after mixing and before drying is weighed and the temperature of the dryer is adjusted to 105° C. for more than 12 hours until the sample is dried to a constant weight.

[0016] Furthermore, in step S4, the required mass of water is calculated according to the corresponding water content, the water is placed in a container, the container is gradually evacuated and given a low-temperature environment to freeze and make ice. After the ice making is completed, the ice cubes are placed in a cold ice crusher to be evenly crushed into small particles for use.

[0017] Furthermore, in step S5, before the ice-soil mixing, the ice-soil mixing equipment and related equipment and the simulated lunar soil particles are pre-cooled with liquid nitrogen, and the ice particles and simulated lunar soil particles are poured into the pre-cooled mixing equipment. Under low temperature conditions, the sample is continuously stirred, and a slow-first-fast-then-fast operation method is implemented to achieve uniform mixing of the sample.

[0018] Furthermore, in step S6, before the dense container is filled, strain gauges are first attached to its side walls in an array and the strain gauges are calibrated at room temperature.

[0019] Furthermore, in step S7, the low-temperature shaping process adopts a static compaction method under a low-temperature environment.

[0020] Furthermore, in step S7, in order to ensure the uniformity of the density of the sample along the depth direction, the densification and shaping process needs to divide the sample evenly, fill and compact in batches, add layer by layer, and compact layer by layer.

[0021] Furthermore, in step S8, the placeholder bolts are pulled out, and sensors are arranged in an array by drilling holes at corresponding positions. The sensors are inserted into the sensor holes through the hollow bolts, wrapped with raw tape, and the bolts are tightened.

[0022] Furthermore, in step S9, the low-temperature environment is maintained after the low-temperature shaping, and a stress aging applying device is used to apply confining pressure to the sample, and corresponding pressure and temperature data are collected.

[0023] Compared with the prior art, the method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing described in the present invention has the following beneficial effects:

[0024] Through the sample preparation process of the present invention, the ice is frozen and crushed separately and then evenly mixed with the dry and cooled simulated lunar soil sample, so that the moisture content of each part of the entire sample is relatively uniform and reaches a controllable level. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a flow chart of the method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to the present invention;

[0027] Figure 2 This is a schematic diagram of the principle of the method for preparing polar water-containing simulated lunar soil based on ice-soil mixing described in the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0029] 1. Specific implementation method 1, see Figure 1-2 This embodiment is described as follows. Figure 1 As shown in the figure, the preparation process of polar region water-containing simulated lunar soil based on ice-soil mixing includes 11 steps: basic raw material preparation and selection, raw material mixing, drying, pre-cooling, moisture content detection, ice particle preparation, ice-soil mixing, stress sensing pre-setting, low-temperature shaping, low-temperature sensing pre-setting, and low-temperature stress aging. Specifically, they are:

[0030] Step S1: Preparation of dry soil raw materials: selecting the components and particle shapes of the raw materials, mixing the selected particles of different components in a certain proportion, and drying the mixed raw materials;

[0031] Step S2: pre-cooling each preparation device before preparation;

[0032] Step S3: Calculating the initial moisture content;

[0033] Step S4: ice particle preparation: quantitatively prepare water, freeze it, and then crush it into small particles for later use;

[0034] Step S5: mixing the ice particles with the dried soil raw material;

[0035] Step S6: presetting the dense attached barrel stress sensor in a low temperature environment;

[0036] Step S7: compacting the mixed sample layer by layer in a low temperature environment;

[0037] Step S8: Presetting the temperature sensor of the compacting barrel;

[0038] Step S9: Maintaining the sample under confining pressure for a long time under ultra-low temperature conditions.

[0039] The entire process requires careful selection of raw materials based on their mineral composition, particle size distribution, and micromorphology, followed by proportional mixing and drying of the base raw materials. Pre-cooling involves pre-cooling the dry soil particles and the entire experimental tooling. Ice particle preparation involves measuring the mass of water to be frozen based on its moisture content. Ice is then produced in a low-temperature vacuum environment. Once frozen, the ice is crushed using a cold crushing device. Ice-soil mixing must be performed at low temperatures, with uniform mixing achieved while controlling the stirring speed. Stress sensing pre-setting involves attaching strain gauges in an array to the inner wall of a compacting barrel and calibrating them at room temperature. The sample within the compacting barrel is then statically compacted at low temperatures. After compaction, low-temperature sensors are pre-placed on the barrel's sidewalls. Following pre-setting, the entire sample is subjected to a prolonged confining pressure.

[0040] Each sample processing device must be cooled before use to prevent the device temperature from being too high, which will affect the moisture content and sample temperature of the sample.

[0041] (1) Preparation of dry soil raw materials

[0042] Based on the mineral composition of polar lunar regolith, plagioclase and basalt were selected as the raw materials for preparing the simulated lunar regolith. Since polar lunar regolith is primarily less than 1 mm in particle size, angular and sub-angular shapes were selected, with a particle size of 0-1 mm. A certain amount of plagioclase and basalt were mixed in a specific proportion and blended uniformly using a blender. The sample was weighed before drying and the dryer temperature was set to 105°C for at least 12 hours until constant weight was achieved. The dried sample was weighed and the initial moisture content was calculated using the formula.

[0043] (2) Ice particle preparation

[0044] Calculate the required water mass according to the corresponding water content, put the water in a container, gradually evacuate the container and give it a low-temperature environment to freeze and make ice. After the ice making is completed, put the ice cubes in a cold ice crusher to evenly crush them into small particles for use.

[0045] (3) Ice-soil mixing

[0046] Before mixing the ice and soil, the mixing equipment, related equipment, and simulated lunar soil particles were pre-cooled with liquid nitrogen. The ice and simulated lunar soil particles were then poured into the pre-cooled mixing equipment. At low temperatures, the samples were continuously stirred, starting slowly and then accelerating to achieve uniform mixing.

[0047] (4) Stress sensor pre-setting and dense attachment

[0048] Before filling a dense container, strain gauges are first applied to its sidewalls in an array pattern and calibrated at room temperature. The low-temperature shaping process uses static compaction at low temperatures. To ensure uniform density along the depth of the sample, the sample is added and compacted layer by layer.

[0049] (5) Low temperature sensor preset

[0050] Pull out the placeholder bolts, drill holes in an array at the corresponding positions to arrange the sensors, insert the sensors through the hollow bolts into the sensor holes, wrap them with raw tape, and tighten the bolts.

[0051] (6) Low temperature stress aging

[0052] After low-temperature shaping, the low-temperature environment is maintained. A stress aging device is used to apply confining pressure to the sample, and the corresponding pressure and temperature data are collected. The confining pressure must be maintained for 24 hours during the stress aging process.

[0053] This invention primarily addresses sample preparation control points from the perspectives of moisture uniformity and defect control. The process flow and methods required for each step are planned. To provide conditions for subsequent sample collection, the uniform ice-soil mixed sample preparation process is divided into two major components: the first preparation and the second preparation. The first preparation results in an ice-soil mixed sample, a thorough blend of ice particles and dry soil. The second preparation results in a sample that has been given strength and density through layered compaction and stress aging.

[0054] The design principle of the present invention is to start from the perspective of large-scale engineering tests and aim to meet the sample conditions required for engineering tests. In the past, during the freezing process of water ice in cross-section samples, the freezing rate at the sample boundary would be stronger than that inside the sample, causing the sample boundary temperature to be lower than the sample center. Due to the principle of cold-end migration of moisture, the moisture inside the sample will migrate to the surrounding area, causing the moisture content at the sample boundary to be higher than that in the sample center. The moisture content of the entire sample is uneven, and the strength and hardness of samples with different moisture contents are also different. As a result, the stress, drilling power and moisture content per drilled during the sample drilling process in later tests cannot be unified, and the variables cannot be controlled, resulting in the drilling test data obtained later having no reference significance.

[0055] The method for preparing polar region water-containing simulated lunar soil mixed with ice and soil in the present invention is designed to meet the moisture uniformity of the entire sample. The process flow and method for preparing profile samples are designed. The preparation is convenient, the moisture content is controllable, and the measurability of the moisture content is also good. Compared with other methods for preparing simulated lunar soil water ice, it has a short cycle, a simple process, and a low cost, which can meet the controllability of variables at each sampling point of the profile sample in subsequent engineering tests.

[0056] The embodiments of the present invention disclosed above are intended only to illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A method for preparing polar region water-containing simulated lunar regolith based on ice-soil mixing, characterized by: The specific steps include: Step S1: Preparation of dry soil raw materials: selecting the components and particle shapes of the raw materials, mixing the selected particles of different components in a certain proportion, and drying the mixed raw materials; Step S2: pre-cooling each preparation device before preparation; Step S3: Calculating the initial moisture content; Step S4: ice particle preparation: quantitatively prepare water, freeze it, and then crush it into small particles for later use; Step S5: mixing the ice particles with the dried soil raw material; Step S6: presetting the dense attached barrel stress sensor in a low temperature environment; Step S7: compacting the mixed sample layer by layer in a low temperature environment; Step S8: Presetting the temperature sensor of the compacting barrel; Step S9: Under ultra-low temperature conditions, the sample is subjected to a long-term confining pressure maintenance using a stress aging device.

2. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S1, plagioclase and basalt are selected as raw materials for preparing simulated lunar soil based on the mineral composition of the polar lunar soil, and the particle size of the polar lunar soil is less than 1 mm.

3. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1 or 2, characterized in that: In step S1, the mass of the sample after mixing and before drying is weighed and the temperature of the dryer is adjusted to 105° C. for more than 12 hours until the sample is dried to a constant weight.

4. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S4, the required water mass is calculated according to the corresponding water content, the water is placed in a container, the container is gradually evacuated and given a low-temperature environment to freeze and make ice. After the ice making is completed, the ice cubes are placed in a cold ice crusher to be evenly crushed into small particles for use.

5. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S5, before mixing the ice and soil, liquid nitrogen is used to pre-cool the ice and soil mixing equipment, related equipment, and simulated lunar soil particles. The ice particles and simulated lunar soil particles are poured into the pre-cooled mixing equipment. Under low temperature conditions, the sample is continuously stirred, and a slow-first-fast-then operation method is implemented to achieve uniform mixing of the sample.

6. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S6, before the dense container is filled, strain gauges are first attached to its side walls in an array and the strain gauges are calibrated at room temperature.

7. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S7, the low-temperature shaping process adopts a static compaction method under a low-temperature environment.

8. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 7, characterized in that: In step S7, in order to ensure the uniformity of the density of the sample along the depth direction, the sample needs to be evenly divided into equal parts during the densification and shaping process, and filled and compacted in batches, added layer by layer, and compacted layer by layer.

9. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S8, the placeholder bolts are pulled out, and the sensors are arranged in an array by drilling holes at the corresponding positions. The sensors are inserted into the sensor holes through the hollow bolts, wrapped with raw tape, and the bolts are tightened.

10. The method for preparing polar region water-containing simulated lunar soil based on ice-soil mixing according to claim 1, characterized in that: In step S9, the low-temperature environment is maintained after the low-temperature shaping, and a stress aging applying device is used to apply confining pressure to the sample, and the corresponding pressure and temperature data are collected.

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