Test system and test method for water vapor migration in soil freezing and thawing process

Abstract

The invention provides a test system and a test method for water vapor migration in a soil freezing and thawing process, and the test system is provided with a soil sample loading device, a refrigeration system, a water supplementing system, a traffic load simulation system, an air pressure control system and a data analysis system. The influence of contact water replenishing, non-contact water replenishing and non-water replenishing on water vapor migration in the one-dimensional freezing and thawing process of the soil can be realized; the influence of different temperatures and different freezing times on water vapor migration in the soil freezing and thawing process is researched by adjusting the temperature and the freezing time of the refrigerating device; by adjusting the frequency and the size of the output load, the influence of the traffic load effect on the water vapor migration of the soil body in the soil freezing and thawing process is researched. The device is simple, and research and visual display of the influence of soil moisture migration under different water replenishing conditions, freezing and thawing temperatures, freezing and thawing time and traffic load conditions can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field related to soil freeze-thaw water vapor migration test, and in particular relates to a test system and a test method for water vapor migration during soil freeze-thaw process. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The frost heave and thaw settlement of soil in permafrost areas can easily induce cracks and uneven settlement of pavements of airports, railways and highways, posing a serious threat to the long-term service performance of infrastructure in permafrost areas. Scholars have found that the migration of water vapor during the freezing and thawing of soil is the main cause of frost heave and thaw settlement of soil. At the same time, traffic loads also have a great impact on the temperature and structural characteristics of frozen soil, thereby changing the migration of water vapor during the freezing and thawing of soil.

[0004] Patent 202223324553.1 discloses a test system for unidirectional freezing water vapor migration in soil. The device has a complex structure and a cumbersome process. It has not yet considered the impact of traffic load and air pressure environment on soil water vapor migration, and cannot achieve visualization of the soil freezing and thawing process.

[0005] Therefore, in order to explore the water vapor migration law of soil freezing and thawing process under traffic load and air pressure environment, and to realize the data monitoring and visualization of water vapor migration during soil freezing and thawing process under complex environment, it is necessary to design a set of water vapor migration test equipment during soil freezing and thawing process, so as to reveal the influence of various influencing factors on water vapor migration during soil freezing and thawing process. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a test system and test method for water vapor migration during soil freezing and thawing. The device is simple and can realize the research and visualization of the influence of soil water vapor migration under different water replenishment conditions, freezing and thawing temperatures, freezing and thawing times, and traffic load conditions, so as to better serve the research on roadbed engineering diseases in frozen soil areas.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a test system for water vapor migration during soil freezing and thawing, comprising: a soil sample loading device, a refrigeration system, a water replenishment system, a traffic load simulation system, an air pressure control system, and a data analysis system;

[0009] The soil sample loading device comprises a light-transmitting box, a porous steel plate is arranged in the light-transmitting box, and soil is filled in the light-transmitting box and above the porous steel plate;

[0010] The refrigeration system includes a refrigeration device, which provides temperature conduction with adjustable temperature and freezing time for the soil in the light-transmitting box in a non-contact manner, thereby simulating the freezing and thawing state of the soil;

[0011] The water replenishment system includes a liquid supply bottle, which provides liquid to the space enclosed by the light-transmitting box and the porous steel plate, and switches between contact water replenishment, non-contact water replenishment and no water replenishment for the soil by controlling the height of the liquid supply bottle; the liquid in the liquid supply bottle uses a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is achieved by tracking the fluorescent tracer solution;

[0012] The traffic load simulation system includes a pressure plate and a driving servo motor, and the driving servo motor outputs a load to the soil through the pressure plate to achieve traffic load simulation with adjustable frequency and size;

[0013] The air pressure control system includes a vacuum pump, and the vacuum pump is used to change the air pressure environment of the soil;

[0014] The data analysis system is used to analyze the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process, and study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

[0015] In a second aspect, the present invention provides a test method for water vapor migration during soil freezing and thawing, comprising:

[0016] The refrigeration system provides temperature conduction with adjustable temperature and freezing time to the soil in the soil sample loading device, so as to simulate the freezing and thawing state of the soil;

[0017] Liquid is supplied to the space enclosed by the light-transmitting box and the porous steel plate through a water supply system, and the switching of different states of contact water supply, non-contact water supply and no water supply to the soil is realized by controlling the height of the liquid supply bottle; wherein the liquid in the liquid supply bottle adopts a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is realized by tracking the fluorescent tracer solution;

[0018] The traffic load simulation system provides the soil with an output load with adjustable frequency and size to simulate the soil traffic load.

[0019] Change the air pressure environment of the soil through the air pressure control system;

[0020] Through the data analysis system, the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process are analyzed to study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

[0021] One or more of the above technical solutions have the following beneficial effects:

[0022] In the present invention, by setting up a soil sample loading device, a refrigeration system, a water replenishment system, a traffic load simulation system, an air pressure control system, and a data analysis system, the influence of contact water replenishment, non-contact water replenishment, and no water replenishment on water vapor migration during one-dimensional freezing and thawing of soil can be realized; by adjusting the temperature and freezing time of the refrigeration device, the influence of different temperatures and different freezing times on water vapor migration during freezing and thawing of soil can be studied; by adjusting the frequency and size of the output load, the influence of traffic load on soil water vapor migration during freezing and thawing of soil can be studied. The device of the present invention is simple, and can realize the research and visualization display of the influence of soil water vapor migration under different water replenishment conditions, freezing and thawing temperatures, freezing and thawing times, and traffic load conditions, so as to better serve the research on roadbed engineering diseases in frozen soil areas.

[0023] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 This is a schematic diagram of the overall structure of a test system for water vapor migration during soil freezing and thawing in Example 1 of the present invention;

[0026] In the figure, 11, top refrigeration device; 12, bottom refrigeration device; 13, bottom circulating cold bath plate; 14, top circulating cold bath plate; 21, Martens flask; 22, water outlet; 23, porous steel plate; 31, first thermo-TDR sensor; 32, second thermo-TDR sensor; 33, third thermo-TDR sensor; 34, fourth thermo-TDR sensor; 35, fifth thermo-TDR sensor; 41, pressure plate; 42, screw drive servo motor; 43, power supply; 51, vacuum pump; 61, first ultraviolet lamp; 62, second ultraviolet lamp; 63, high-speed camera equipment; 7, acrylic cylinder; 8, displacement meter; 91, data acquisition device; 92, computer. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0028] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0029] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0030] Embodiment 1

[0031] This embodiment discloses a test system for water vapor migration during soil freezing and thawing, comprising:

[0032] Soil sampling device, refrigeration system, water supply system, traffic load simulation system, air pressure control system and data analysis system;

[0033] The soil sample loading device comprises a light-transmitting box, a porous steel plate is arranged in the light-transmitting box, and soil is filled in the light-transmitting box and above the porous steel plate;

[0034] The refrigeration system includes a refrigeration device, which provides temperature conduction with adjustable temperature and freezing time for the soil in the light-transmitting box in a non-contact manner, thereby simulating the freezing and thawing state of the soil;

[0035] The water replenishment system includes a liquid supply bottle, which provides liquid to the space enclosed by the light-transmitting box and the porous steel plate, and switches between contact water replenishment, non-contact water replenishment and no water replenishment for the soil by controlling the height of the liquid supply bottle; the liquid in the liquid supply bottle uses a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is achieved by tracking the fluorescent tracer solution;

[0036] The traffic load simulation system includes a pressure plate and a driving servo motor, and the driving servo motor outputs a load to the soil through the pressure plate to achieve traffic load simulation with adjustable frequency and size;

[0037] The air pressure control system includes a vacuum pump, and the vacuum pump is used to change the air pressure environment of the soil;

[0038] The data analysis system is used to analyze the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process, and study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

[0039] Combine the following Figure 1 The test system proposed in this embodiment is described in detail.

[0040] In this embodiment, the refrigeration system, water supply system, and traffic load simulation system are respectively located at both ends, the bottom, and the top of the soil sampling device, the thermo-TDR sensor is located inside the soil sampling device, the fluorescent tracing technology is located on the right side of the soil sample, and the data analysis system is connected to the data acquisition system and the fluorescent tracing system.

[0041] In this embodiment, the soil sampling device includes a light-transmitting box and thermal insulation cotton. The light-transmitting box can be specifically made of an acrylic cylinder 7. A side hole is drilled on the same side of the acrylic cylinder 7 to reserve a position for arranging a thermo-TDR sensor. A porous steel plate 23 is installed near the bottom of the acrylic cylinder 7. The space formed by the acrylic cylinder 7 under the porous steel plate 23 is connected to the water replenishment system, and water is supplied to the space above the porous steel plate 23.

[0042] The acrylic cylinder 7 can provide lateral constraints for the soil, ensure the shape characteristics of the soil, and at the same time ensure that the ultraviolet light can penetrate the acrylic cylinder 7 to realize the visualization of the migration of liquid water in the soil. The thermal insulation cotton is used to fill some of the holes in the acrylic cylinder 7 and wrap the entire acrylic cylinder 7 to reduce the heat diffusion of the soil to the outside.

[0043] Optionally, refer to the triaxial test and resonant column test specimen standards of the "Standard for Geotechnical Test Methods" GB / T 50123-2019, and the soil column height h / diameter D meets 2.5-3.0. The soil sample of this model has a diameter of 30 cm and a height of 90 cm.

[0044] Optionally, the holes of the acrylic cylinder 7 are drilled at a spacing of 15 cm.

[0045] Optionally, the light transmittance of the acrylic cylinder 7 exceeds 95%.

[0046] In this embodiment, the refrigeration system includes a top refrigeration device 11 and a bottom refrigeration device 12. The top refrigeration device 11 is connected to the top circulating cold bath plate 14, and the bottom refrigeration device 12 is connected to the bottom circulating cold bath plate 13. The top circulating cold bath plate 14 and the bottom circulating cold bath plate 13 are respectively in non-direct contact with the top and bottom of the soil sample, and use non-contact heat conduction to circulate input and output of low-temperature gas, thereby changing the temperature of the soil sample. By controlling the input temperature and time of the bottom refrigeration device 12 and the top refrigeration device 11, the freezing and thawing state simulation of the soil sample is realized.

[0047] Optionally, the temperature input range of the bottom refrigeration device 12 and the top refrigeration device 11 is -25°C to 150°C, meeting the freezing and thawing requirements of the soil.

[0048] Optionally, the top circulating cold bath plate 14 and the bottom circulating cold bath plate 13 are made of heat-conducting copper tubes.

[0049] In this embodiment, the water replenishment system includes a Martens flask 21, a rubber-plastic hose, a water outlet 22, and a porous steel plate 23. The position of the Martens flask 21 is fixed by a fixed bracket, and the Martens flask 21 is connected to the water outlet 22 at the bottom of the acrylic cylinder 7 through a rubber-plastic hose. A porous steel plate 23 is arranged near the bottom of the acrylic cylinder 7, and a soil sample is arranged above the porous steel plate 23. The porous steel plate 23 can guide water to evenly replenish the soil sample and reduce capillary phenomena. Among them, a unidirectional permeable membrane is laid between the porous steel plate 23 and the soil sample to achieve unidirectional water replenishment of the soil sample.

[0050] By adjusting the height of the Martens flask 21 and controlling whether the water level in the acrylic cylinder 7 contacts the porous steel plate 23, the influence of soil contact hydration, non-contact hydration and no hydration on the migration of water vapor inside the soil can be studied.

[0051] In this embodiment, the monitoring system includes a thermo-TDR sensor, which is arranged inside the soil sample. The thermo-TDR sensor is arranged longitudinally inside the soil sample. A thermocouple and a resistance wire are arranged inside the probe of the thermo-TDR sensor. The accurate measurement of the water content, ice content, compaction degree, soil temperature and freeze-thaw curve of the soil can be achieved by detecting the dielectric constant, conductivity, heat capacity parameters and temperature of the soil.

[0052] Optional, the probe of the thermo-TDR sensor is 20 cm long and 0.4 cm in diameter. The thermo-TDR sensors are spaced 15 cm apart.

[0053] Optionally, five holes are arranged at equal intervals on the same side of the acrylic cylinder 7 , and the first thermo-TDR sensor 31 , the second thermo-TDR sensor 32 , the third thermo-TDR sensor 33 , the fourth thermo-TDR sensor 34 and the fifth thermo-TDR sensor 35 are placed therein respectively.

[0054] In this embodiment, the traffic load simulation system includes a pressure plate 41, a screw-driven servo motor 42, and a power supply 43. The bottom of the pressure plate 41 is in direct contact with the soil sample; the power supply 43 can further control the output load of the screw-driven servo motor 42 by adjusting the input voltage, and the pressure plate 41 evenly transfers the stress to the soil sample to eliminate the uneven depression on the surface of the soil sample caused by the stress.

[0055] Optionally, the pressure plate 41 has a thickness of 1 cm.

[0056] Optionally, the screw-driven servo motor 42 has an inner diameter of 10 cm and a maximum output load of 30 KN, meeting the requirements of the load simulation test.

[0057] Optionally, the input value of the power supply 43 can be programmably controlled to adjust the output load of the screw drive servo motor 42 to achieve indoor simulation of sinusoidal traffic loads.

[0058] In this embodiment, the air pressure control system includes a vacuum pump 51 and a rubber-plastic hose. One end of the rubber-plastic hose is connected to the top of the soil sample, and the other end of the rubber-plastic hose is connected to the vacuum pump 51. By controlling the input value of the vacuum pump 51, the air pressure environment of the soil is changed.

[0059] In this embodiment, the fluorescent tracer system includes a fluorescent tracer, a first ultraviolet lamp 61, a second ultraviolet lamp 62, and a high-speed camera 63. The fluorescent tracer and distilled water are prepared into a fluorescent tracer solvent, and are injected into the Malchnitz flask 21 in advance, that is, the fluorescent tracer solution is used in subsequent water replenishment tests; the fluorescent tracer solvent is bright green under the irradiation of the first ultraviolet lamp 61 and the second ultraviolet lamp 62 with a wavelength of 365nm, that is, when liquid water exists, the fluorescent tracer solution is bright green under the irradiation of the ultraviolet lamp, and when the liquid water turns into ice, the bright green disappears, realizing the visualization of liquid water migration during the freezing and thawing process of the soil; through the high-speed camera 63, the real-time image of soil fluorescence changes is obtained, and the changing trend of fluorescent spots during the freezing and thawing process of the soil is recorded.

[0060] In this embodiment, the top of the displacement meter 8 is constrained by the top circulating cold bath plate 14, and the bottom is in contact with the pressure plate 41. When the soil sample is subjected to the stress of the screw-driven servo motor 42 and the freezing and thawing process, the soil sample will produce a certain deformation. The deformation process of the soil under the coupling of multiple physical fields is collected through the displacement meter 8.

[0061] In this embodiment, the data acquisition and processing system includes a data acquisition device 91 and a computer 92. The data acquisition device 91 can collect data such as temperature, dielectric constant, conductivity, etc. collected by the first thermo-TDR sensor 31, the second thermo-TDR sensor 32, the third thermo-TDR sensor 33, the fourth thermo-TDR sensor 34, and the fifth thermo-TDR sensor 35 in real time, and the image taken by the high-speed camera 63, and transmit them to the computer 92, and through thermo-TDR software processing and water vapor migration image processing, the accurate detection of moisture content, ice content, compaction degree, temperature, freeze-thaw curve and visualization of water vapor migration in the soil freezing and thawing process under the coupling of multiple physical fields can be realized.

[0062] In terms of soil sample preparation, a pre-established test plan is used and multi-layer filling is performed, with each layer being 15 cm thick. The sensor layers need to be roughened and the thermo-TDR sensors are laid. When everything is ready, soil freezing water vapor migration and visualization tests with controllable loads (dynamic loads, static loads, no loads), controllable water replenishment (contact water replenishment, non-contact water replenishment, no water replenishment), controllable temperature, controllable one-dimensional freezing methods (one-way freezing, two-way freezing), and controllable air pressure (positive pressure, negative pressure, normal pressure) can be carried out according to the test requirements. The moisture content, ice content, compaction degree, temperature and other data during the freezing and thawing process of the soil can also be obtained, as well as freeze-thaw curves, moisture content distribution diagrams, etc.

[0063] A method for conducting a water vapor migration test during soil freezing and thawing using the above test system comprises the following steps:

[0064] Step 1: Pass the soil collected on site through a 1mm sieve, dry it, and prepare the wet soil according to the optimal moisture content.

[0065] Step 2: Close the reserved holes of the soil sampling device, load the wet soil into the soil sampling device, and fill it in layers. Each layer is 15 cm thick. The sensor layers need to be roughened and thermo-TDR sensors are laid to ensure the overall uniformity of the soil sample and complete the soil sample preparation.

[0066] Step 3: Connect the refrigeration system, adjust the refrigeration temperature according to the test conditions, and turn on the refrigeration device after the test begins.

[0067] Step 4: Pour the fluorescent tracer solution into the Martens flask, install the Martens flask on the bracket, ensure that it is connected to the box through a rubber hose, and switch the test conditions between contact water replenishment, non-contact water replenishment or no water replenishment by controlling the height of the Martens flask.

[0068] Step 5: Adjust the position of the pressure plate so that the bottom of the pressure plate is in full contact with the soil sample to ensure uniform load transfer. Set the load size and frequency required for the test through computer software to simulate traffic load.

[0069] Step 6: Adjust the air pressure control system, ensure that the vacuum pump is correctly installed and leak-free, control the air pressure value according to the test requirements, and use a barometer to monitor the air pressure changes to ensure that it is within the preset range.

[0070] Step 7: Record the changes of relevant parameters of soil during the freeze-thaw test through the data analysis system.

[0071] Step 8: After the test, gradually reduce the vacuum pump input intensity to ensure that the air pressure gradually returns to normal pressure to ensure the safety of the test personnel.

[0072] In this embodiment, by adjusting the vertical height of the Mach flask, the effects of contact water replenishment, non-contact water replenishment and no water replenishment on water vapor migration during one-dimensional freezing and thawing of the soil can be studied; by controlling the input refrigeration temperature and freezing time of the refrigeration system, the effects of different positive temperatures, negative temperatures, and top temperature gradients on water vapor migration during freezing and thawing of the soil can be studied; by running the refrigeration system set at the top and shutting down the refrigeration system set at the bottom, the freezing depth, moisture content, and ice content distribution of different soil types under different freezing conditions can be studied; by adjusting the size and frequency of the traffic load, the effect of the traffic load on the water vapor migration of the soil during freezing and thawing of the soil can be studied; by setting the input value of the vacuum pump, the air pressure environment in the soil sample test environment can be controlled; by controlling the cold air input time, the effect of freezing and thawing time on the migration of water vapor inside the soil can be studied; by changing the soil's own parameters, the effects of soil type, initial moisture content, soil grading and other factors on water vapor migration can be studied.

[0073] Embodiment 2

[0074] The purpose of this embodiment is to provide a test method for water vapor migration during soil freezing and thawing, including:

[0075] The refrigeration system provides temperature conduction with adjustable temperature and freezing time to the soil in the soil sample loading device, so as to simulate the freezing and thawing state of the soil;

[0076] Liquid is supplied to the space enclosed by the light-transmitting box and the porous steel plate through a water supply system, and the switching of different states of contact water supply, non-contact water supply and no water supply to the soil is realized by controlling the height of the liquid supply bottle; wherein the liquid in the liquid supply bottle adopts a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is realized by tracking the fluorescent tracer solution;

[0077] The traffic load simulation system provides the soil with an output load with adjustable frequency and size to simulate the soil traffic load.

[0078] Change the air pressure environment of the soil through the air pressure control system;

[0079] Through the data analysis system, the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process are analyzed to study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

[0080] In this embodiment, according to the adjustment of the size and frequency of traffic load, the influence of traffic load on soil water vapor migration during soil freezing and thawing is studied; according to the different states of contact water replenishment, non-contact water replenishment and no water replenishment during soil one-dimensional freezing and thawing, the influence on water vapor migration is studied; according to the different refrigeration temperatures and freezing times input by the refrigeration device, the influence of different positive temperatures, negative temperatures and top temperature gradients on water vapor migration during soil freezing and thawing, as well as the influence of different freezing and thawing times on soil internal water vapor migration are studied. By changing the working mode of the refrigeration device at different positions, the influence of the freezing depth, water content and ice content distribution of different soil types under different freezing conditions is studied.

[0081] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A test system for water vapor migration during soil freezing and thawing, characterized in that: include: Soil sampling device, refrigeration system, water supply system, traffic load simulation system, air pressure control system and data analysis system; The soil sample loading device comprises a light-transmitting box, a porous steel plate is arranged in the light-transmitting box, and soil is filled in the light-transmitting box and above the porous steel plate; The refrigeration system includes a refrigeration device, which provides temperature conduction with adjustable temperature and freezing time for the soil in the light-transmitting box in a non-contact manner, thereby simulating the freezing and thawing state of the soil; The water replenishment system includes a liquid supply bottle, which provides liquid to the space enclosed by the light-transmitting box and the porous steel plate, and switches between contact water replenishment, non-contact water replenishment and no water replenishment for the soil by controlling the height of the liquid supply bottle; the liquid in the liquid supply bottle uses a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is achieved by tracking the fluorescent tracer solution; The traffic load simulation system includes a pressure plate and a driving servo motor, and the driving servo motor outputs a load to the soil through the pressure plate to achieve traffic load simulation with adjustable frequency and size; The air pressure control system includes a vacuum pump, and the vacuum pump is used to change the air pressure environment of the soil; The data analysis system is used to analyze the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process, and study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

2. A test system for water vapor migration during soil freezing and thawing as claimed in claim 1, characterized in that: It also includes a data acquisition system, which is communicatively connected to the data analysis system. The data acquisition system includes a thermo-TDR sensor and an image acquisition device. The thermo-TDR sensor is arranged at different positions in the light-transmitting box and is used to collect dynamic characteristic parameters during soil freezing and thawing; the image acquisition device is used to collect visual images during soil freezing and thawing.

3. A test system for water vapor migration during soil freezing and thawing as claimed in claim 1, characterized in that: The refrigeration system also includes a circulating cold bath plate, the refrigeration device is connected to the circulating cold bath plate, and the circulating cold bath plates are respectively arranged on the top and bottom of the soil and are arranged in non-contact with the soil.

4. A test system for water vapor migration during soil freezing and thawing as claimed in claim 1, characterized in that: It also includes a violet lamp, which is used to irradiate the soil containing the fluorescent tracer solvent to achieve a visual display of liquid water migration during soil freezing and thawing.

5. A test system for water vapor migration during soil freezing and thawing as claimed in claim 3, characterized in that: It also includes a displacement meter, one end of which is arranged on the circulating cold bath plate, and the other end of which is arranged on the pressure plate. The displacement meter is used to measure the deformation process of the soil under the coupling of multiple physical fields.

6. A test system for water vapor migration during soil freezing and thawing as claimed in claim 1, characterized in that: A one-way permeable membrane is laid between the porous steel plate and the soil to achieve one-way replenishment of soil moisture.

7. A test system for water vapor migration during soil freezing and thawing as claimed in claim 2, characterized in that: A plurality of side holes are arranged at equal intervals on the same side of the light-transmitting box body, the thermo-TDR sensor is arranged at the position of each side hole, and thermal insulation cotton is filled between the side hole and the thermo-TDR sensor.

8. A test method for water vapor migration during soil freezing and thawing, characterized in that: include: The refrigeration system provides temperature conduction with adjustable temperature and freezing time to the soil in the soil sample loading device, so as to simulate the freezing and thawing state of the soil; Liquid is supplied to the space enclosed by the light-transmitting box and the porous steel plate through a water supply system, and the switching of different states of contact water supply, non-contact water supply and no water supply to the soil is realized by controlling the height of the liquid supply bottle; wherein the liquid in the liquid supply bottle adopts a fluorescent tracer solution, and the visualization of liquid water migration during soil freezing and thawing is realized by tracking the fluorescent tracer solution; The traffic load simulation system provides the soil with an output load with adjustable frequency and size to simulate the soil traffic load. Change the air pressure environment of the soil through the air pressure control system; Through the data analysis system, the dynamic characteristic parameters and visual images collected during the soil freezing and thawing process are analyzed to study the water vapor migration law during the soil freezing and thawing process under different loads, water replenishment conditions, freezing methods and air pressures.

9. A test method for water vapor migration during soil freezing and thawing as claimed in claim 8, characterized in that: Also includes: According to the size and frequency of traffic load, the influence of traffic load on soil water vapor migration during soil freezing and thawing is studied; According to the different states of contact water replenishment, non-contact water replenishment and no water replenishment during the one-dimensional freezing and thawing process of soil, the influence on water vapor migration is studied; According to the different refrigeration temperatures and freezing times input by the refrigeration device, the effects of different positive temperatures, negative temperatures, and top temperature gradients on water vapor migration during soil freezing and thawing, as well as the effects of different freezing and thawing times on water vapor migration inside the soil are studied.

10. A test method for water vapor migration during soil freezing and thawing as claimed in claim 8, characterized in that: By changing the working mode of the refrigeration device at different locations, the influence of freezing depth, moisture content and ice content distribution of different soil types under different freezing conditions is studied.

Images