Device for simulating migration of water and salt in soil body under freeze-thaw cycle

Abstract

The utility model discloses a simulation device for water and salt migration in a soil body under freeze-thaw cycle, which relates to the technical field of water and salt migration simulation devices and comprises a visual acrylic test barrel, an upper temperature conducting disc, a lower temperature conducting disc, a water and salt supply device, a fluorescent agent, a blue light lamp, a data acquisition instrument, a plurality of hydrothermal salt sensors, a water level monitor and two low-temperature thermostatic baths. According to the design, the problem that the accuracy of a water and salt migration simulation test in a soil body is influenced because the original device cannot observe the soil column change in the freezing and thawing process of the salinized soil from a macroscopic angle is solved. According to the utility model, the vacuum layer is adopted to achieve a heat preservation effect, a fluorescent agent is added into the replenishment liquid, and an internal freezing frontal surface, ice crystals and salt crystals can be observed through the acrylic glass barrel. When water and salt migration in the soil body is simulated, data are more accurate, the reliability of a test result is improved, and the water and salt migration process in the soil column is more visually observed.

Description

Technical Field

[0001] This utility model relates to the technical field of water-salt migration simulation devices, and in particular to a water-salt migration simulation device under freeze-thaw cycles of water-salt migration, ice crystals, salt crystallization, and freezing fronts. Background Technology

[0002] Saline soil, as a special type of soil, possesses unique engineering properties such as collapsibility, salt frost heave, and corrosivity. In Northwest China, with its low average annual rainfall, significant high-temperature evaporation, and large diurnal temperature range, coupled with the gradual rise in groundwater levels in recent years, the combined effects of temperature and water lead to increased capillary rise and significant salt accumulation on the surface. This alters the water-salt environment at the subgrade and the interface between the subgrade and road base, resulting in varying degrees of salt corrosion damage and significantly reducing the service life of road projects. Therefore, simulating water-salt migration in saline soil is crucial. Seasonally frozen soil areas account for 53.5% of my country's total area, and these regions are often accompanied by soil salinization. To address soil salinization, domestic and international scholars have conducted numerous indoor experiments to simulate temperature changes in seasonally frozen zones.

[0003] Current technologies utilize large-scale test chambers for indoor water-salt migration experiments to observe changes in soil hydrothermal salt content. However, these large chambers cannot effectively isolate temperature transfer, necessitating insulation to prevent temperature exchange with the external environment during unidirectional heat transfer. Furthermore, the presence of insulation prevents macroscopic observation of water-salt migration, ice crystal formation, salt crystallization, and moisture changes within the test chamber. The migration of water and salt in the soil column must be assessed using a three-parameter instrument sensor.

[0004] Therefore, this utility model proposes a test device that can maintain its insulation effect in a unidirectional temperature transfer freeze-thaw test and also allow for real-time observation of changes inside the soil column from a macroscopic perspective. Utility Model Content

[0005] The purpose of this invention is to address the deficiencies in the existing technology by proposing a device for simulating the migration of water and salt in soil under freeze-thaw cycles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A device for simulating water and salt migration in soil under freeze-thaw cycles includes a visualization test barrel. An upper temperature-conducting plate is located at the top of the test barrel, and a lower temperature-conducting plate is located at the bottom. Both the upper and lower temperature-conducting plates are connected to a low-temperature constant-temperature bath. Sensor channels are provided on both sides of the test barrel, and hydrothermal and salt sensors are adapted and connected within these channels. The hydrothermal and salt sensors are connected to a computer via a data acquisition instrument. A blue light is installed on one side of the test barrel.

[0008] Furthermore, a vacuum layer is provided on the outer wall of the visualization test barrel.

[0009] Furthermore, the visualization test chamber is filled with a sample.

[0010] Furthermore, the low-temperature constant temperature bath is provided with two sets of liquid inlets and two sets of liquid outlets. The upper temperature guide plate is provided with a receiving cavity, which is connected to one set of liquid inlets and one set of liquid outlets through two rubber tubes. The lower temperature guide plate is provided with a receiving cavity, which is connected to another set of liquid inlets and another set of liquid outlets through two rubber tubes.

[0011] Furthermore, an insulation cotton layer is provided on the outside of the rubber tube.

[0012] Furthermore, it also includes a water and salt supply device, which includes a Marshall flask and a water level detector. The water level detector is located inside the Marshall flask and connected to a computer. The Marshall flask contains a salt solution containing a fluorescent agent. The Marshall flask is connected to the upper cavity of the lower temperature guide plate through an inlet pipe. The upper cavity is connected to the interior of the visualization test barrel.

[0013] Beneficial effects

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] (1) The forming system can compact soil columns of different sizes. A channel for placing sensors is set every 10cm. By arranging the channels with the required size and spacing in advance, it is convenient to bury the hydrothermal and salt sensors and ensure the accuracy of the test.

[0016] (2) This utility model can simulate saline soil test of environmental changes and groundwater recharge. It simulates different environmental changes by controlling different temperatures and simulates groundwater salinity by setting water content under different salt levels, thus providing good test conditions for water-salt migration test.

[0017] (3) The present invention is equipped with software to control the temperature rise and fall rate in the low temperature constant temperature bath. The temperature rise and fall rate of the temperature guide plate is controlled by the computer, and the temperature change curve of the temperature guide plate is recorded in the computer.

[0018] (4) This utility model achieves the effect of isolating temperature by adding a vacuum layer on the acrylic glass barrel. Using this acrylic glass barrel, the changes inside the soil column can be observed directly. By combining fluorescent agent and blue light, the migration of water and salt inside the soil column can be observed from a macroscopic perspective.

[0019] (5) The combination of temperature control system, visual test barrel and water and salt supply device realizes a more realistic test environment that simulates the temperature changes of natural environment and the salinity changes of different groundwater.

[0020] (6) The combination of sensors, data acquisition instruments and computers has enabled the automated acquisition and processing of test data, ensuring the reliability of the data. Attached Figure Description

[0021] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0022] Figure 1 A schematic diagram of the overall simulation device.

[0023] Figure 2 A schematic diagram of the visual test barrel in the simulation device.

[0024] Figure 3 Schematic diagram of the temperature control device for the simulation device.

[0025] Figure 4 Schematic diagram of the water and salt supply device for the simulation apparatus.

[0026] In the figure: 1. Low temperature constant temperature bath; 2. Hydrothermal salt sensor; 3. Vacuum layer; 4. Upper temperature guide plate; 5. Lower temperature guide plate; 6. Sensor channel; 7. Marshall flask; 8. Data acquisition instrument; 9. Computer; 10. Visual test barrel; 11. Blue light lamp; 12. Water level detector; 13. Sample. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0028] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] Figure 1 This is a schematic diagram of the overall system. The overall structure consists of a visual test tank, a temperature control device, a computer, a water and salt supply device, and a data acquisition device.

[0030] Figure 2 The visualization test chamber 10 is an acrylic glass barrel with a vacuum layer. The outer wall of the visualization test chamber is provided with a vacuum layer 3, which can achieve the effects of heat preservation and visualization. Channels for placing sensors are opened on both sides of the test chamber. The sensor channels 6 are adapted to the external dimensions of the hydrothermal salt sensor. After the hydrothermal salt sensor is installed, the sensor channels can be sealed to prevent material leakage inside the visualization test chamber. The visualization test chamber 10 is marked with scales inside. A blue light 11 is set on one side of the visualization test chamber to illuminate the visualization test chamber and facilitate the observation of the water and salt migration process during the experiment.

[0031] Figure 3 As a temperature control device, the inlet and outlet of the low-temperature constant temperature bath 1 are connected by rubber tubes that are resistant to freezing and corrosion. The low-temperature constant temperature bath 1 is filled with antifreeze. There are two sets of rubber tubes, which supply the coolant to the lower temperature guide plate 5 and the upper temperature guide plate 4 respectively. The lower temperature guide plate 5 and the upper temperature guide plate 4 have similar structures and are provided with a receiving cavity inside. The receiving cavity is provided with a channel for the coolant to enter and flow out. The temperature control component of the low-temperature constant temperature bath 1 is connected to a computer and indirectly controls the temperature of the temperature guide plate through a program. The rubber tubes in the temperature control device are also covered with a layer of heat insulation cotton.

[0032] Figure 4 The water and salt supply device consists of a Marshall bottle 7 and a water level monitor 12. The water inlet on the right side of the lower temperature guide plate 5 is connected by a rubber tube, and the other end of the rubber tube is connected to the Marshall bottle 7. The water level monitor 12 is connected to a computer to transmit the water and salt supply status to the computer in real time. A fluorescent agent is added to the Marshall bottle 7, and with the help of a blue light lamp 11, the water and salt migration in the sample can be observed in real time and intuitively.

[0033] The data acquisition device includes several water, heat and salt sensors 2, which are placed in the preset sensor channels 6. After the sensors are installed, sealant is injected into the gap between the sensors and the sensor channels. The sensors are connected to the data acquisition instrument 8, and the data acquisition instrument 8 is connected to the computer 9.

[0034] This utility model embodiment provides a test method for a soil water and salt migration test device system under freeze-thaw cycles, including the following steps:

[0035] Step 1: Prepare the test materials according to different experimental requirements, and compact the test soil sample into the visual test bucket in layers.

[0036] Step 2: Based on the groundwater recharge salinity requirements of different simulated regions, prepare solutions with different salinities and add them to the Marshall flask. Add fluorescent agent to the Marshall flask, connect the Marshall flask and the lower temperature conduction plate using a rubber tube, monitor the water-salt recharge rate using a water level monitor, and transmit the data to the computer in real time.

[0037] Step 3: Set the temperature control device according to the changes in ambient temperature in different simulated regions.

[0038] Step 4: Insert the hydrothermal salt sensor into the soil column through the sensor channel, and seal the gap between the sensor and the channel with sealant. Turn on the data acquisition instrument to start collecting the initial state of each layer of hydrothermal salt in the test soil column.

[0039] Step 5: Connect the low-temperature constant temperature bath and the upper and lower temperature guide plates through the rubber tube, add a layer of insulation cotton to the outside of the rubber tube, add antifreeze to the low-temperature constant temperature bath, turn on the low-temperature constant temperature bath, run it for half an hour, and after the instrument is running normally, adjust the temperature according to different test requirements.

[0040] Step 6: After connecting the system, turn on the blue light to observe the changes in water and salt in the test soil column in real time.

[0041] Step 7: Using a computer, set the lower temperature guide plate to a constant 5℃ to simulate the underground soil temperature. Set the initial temperature of the upper temperature guide plate to 5℃. After 24 hours of static setting to allow the soil column to stabilize, lower the upper temperature guide plate to -25℃ to simulate winter nighttime temperatures. After 12 hours, set the upper temperature guide plate back to 5℃ to simulate winter daytime temperatures. Wait another 12 hours, then set the upper temperature guide plate back to -25℃. This 24-hour cycle constitutes one test. Repeat this process 7 times to conduct 7 freeze-thaw cycle tests.

[0042] Step 8: When conducting the soil freeze-thaw cycle test, the number of freeze-thaw cycles and the rate of temperature rise and fall are adjusted by computer according to the requirements.

[0043] Step 9: Turn on the blue light to reduce the indoor brightness. This allows for real-time observation of the migration of fluorescent agents in the test soil during the freeze-thaw cycle, and the data can be transmitted to the computer in real time.

[0044] Step 10: The data acquisition and control system acquires and stores temperature, moisture, and salinity data in the soil in real time. The data processing software on the workstation analyzes and images the acquired data to obtain the dynamic changes of water, heat, and salt in the soil during the freeze-thaw process.

[0045] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A device for simulating water and salt migration in soil under freeze-thaw cycles, characterized in that, The visual test barrel is provided with an upper temperature guide disc at the top and a lower temperature guide disc at the bottom, and the upper temperature guide disc and the lower temperature guide disc are connected with a low-temperature constant-temperature tank; sensor channels are formed in the two sides of the visual test barrel, and a hydrothermal salt sensor is adaptively connected in the sensor channels; the hydrothermal salt sensor is connected with a computer through a data acquisition instrument; and a blue light lamp is arranged on one side of the visual test barrel.

2. The device for simulating water and salt migration in soil under freeze-thaw cycles according to claim 1, characterized in that, The outer wall of the visual test barrel is provided with a vacuum layer.

3. The device for simulating water and salt migration in soil under freeze-thaw cycles according to claim 1, characterized in that, The visual test barrel is filled with a test sample.

4. The device for simulating water and salt migration in soil under freeze-thaw cycles according to claim 1, characterized in that, Two groups of liquid inlets and two groups of liquid outlets are arranged on the low-temperature constant-temperature tank, an accommodating cavity is arranged in the upper temperature guide disc, and the accommodating cavity is connected with one group of liquid inlets and one group of liquid outlets through two rubber tubes; an accommodating cavity is arranged in the lower temperature guide disc, and the accommodating cavity is connected with the other group of liquid inlets and the other group of liquid outlets through two rubber tubes.

5. The device for simulating water and salt migration in soil under freeze-thaw cycles according to claim 4, characterized in that, The rubber tube is externally provided with a heat preservation cotton layer.

6. The device for simulating water and salt migration in soil under freeze-thaw cycles according to claim 1, characterized in that, The water salt supplement device comprises a marshall bottle and a water level detector, the water level detector is arranged on the inner side of the marshall bottle and connected with the computer; the marshall bottle is internally provided with a salt-containing solution, the salt-containing solution contains a fluorescent agent, the marshall bottle is communicated with the upper cavity of the lower temperature guide disc through a liquid inlet pipe, and the upper cavity is communicated with the inside of the visual test barrel.

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