Hydrothermal salt migration determination test device and method for simulating external environment

Abstract

The invention discloses a hydrothermal salt migration determination test device and method for simulating an external environment, and the device comprises a constant temperature box which is used for providing a constant temperature test environment; the rainfall simulation device is arranged at the top of the constant-temperature box and used for simulating an external rainfall environment, and the rainfall simulation device controls the rainfall capacity, the rainfall speed and the rainfall duration through an external controller; the soil column model device is arranged on the inner side of the constant-temperature box and used for containing a test soil sample, a soil column model is arranged in the soil column model device and serves as the test soil sample, a heat preservation layer is arranged on the outer surface of the soil column model, and a glass cover covers the outer side of the soil column model in an attached mode. By integrating the rainfall simulation device, the solar radiation simulation device and the water level simulation device, comprehensive simulation of various external environment factors is realized, the limitation that only a single environment factor can be simulated in the prior art is overcome, the test condition is closer to the actual engineering environment, and the test efficiency is improved. And the reliability and the practical value of a test result are improved.

Description

Technical Field

[0001] The invention relates to the technical field of rock and soil model tests, and in particular to a water, heat and salt migration test device and method for simulating an external environment. Background Art

[0002] Rainfall and solar radiation are common natural phenomena. These changes in the external environment can cause physical and chemical phenomena such as water infiltration and radiation evaporation in the soil, thereby affecting the distribution of water, temperature and salt in the soil, and thus causing changes in the stability and safety of the soil structure. In engineering fields such as earthen site protection, slope stability analysis, and roadbed strength and stability analysis, accurately understanding the changes in water, heat and salt over time is of great significance to engineering practice.

[0003] At present, most of the devices for measuring soil water, heat and salt focus on the control of a single condition, such as studying only a single factor such as temperature change or water infiltration, and lack consideration of the combined effects of multiple environmental factors. In addition, the existing simulation of the water, heat and salt migration process lacks unified standards, and its measurement method often uses small soil-taking tools to take soil from bottom to top in different ranges. This method is easy to cause disturbance to the soil and affect the accuracy of the measurement results. At the same time, the existing technology is also difficult to achieve real-time monitoring of water, heat and salt migration under multiple environmental conditions, and cannot meet the needs of dynamic monitoring and analysis of water, heat and salt inside the soil under long-term conditions.

[0004] At present, there are few devices for studying soil water, heat and salt migration under various external environments such as rainfall and solar radiation, making it difficult to achieve more effective indoor test simulations and understand the internal migration laws of soil. In view of this, there is an urgent need for a device and method that is conducive to measuring soil water, heat and salt migration under multiple environments, which is of great significance for the stability and safety countermeasures of later actual projects. Summary of the invention

[0005] The purpose of the present invention is to provide a water-heat-salt migration test device and method for simulating the external environment, so as to solve the problems existing in the existing soil water-heat-salt measurement device mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution, a water-heat-salt migration test device and method for simulating an external environment, comprising: Constant temperature box, used to provide a constant temperature test environment; A rainfall simulation device is arranged on the top of the thermostatic box and is used to simulate an external rainfall environment. The rainfall simulation device controls the rainfall amount, rainfall speed and rainfall duration through an external controller; A soil column model device is arranged inside the constant temperature box and is used to place the test soil sample. The soil column model device is provided with a soil column model as the test soil sample. The outer surface of the soil column model is provided with a heat preservation layer, and the outer fitting cover of the soil column model is provided with a glass cover. A solar radiation simulation device is arranged on the top of the constant temperature box, and includes at least one group of infrared irradiation lamps, which are symmetrically arranged on both sides of the soil column model device. By adjusting the light intensity, irradiation time and radiation angle of the irradiation lamps, the temperature gradient of the soil column model in the soil column model device is regulated to simulate the influence of solar radiation on the soil column model; A water-heat-salt migration monitoring device is arranged on the glass cover, and is used to monitor the distribution and changes of moisture, temperature and salt in the soil column model along the height of the soil column in real time. The water-heat-salt migration monitoring device includes several groups of mounting ports on the glass cover, temperature sensors, humidity sensors and salt sensors. The several groups of mounting ports are arranged at equal intervals along the axis direction of the soil column model, and the temperature sensors, humidity sensors and salt sensors are connected to the several groups of mounting ports; A water level simulation device is arranged at the inner bottom of the thermostatic box, and is used to simulate the groundwater level and water replenishment. The water level simulation device comprises a push-pull chassis and a water tank arranged on the top of the push-pull chassis. The water level in the water tank is adjustable, and is used to simulate the dynamic change of water in the process of groundwater replenishment and evaporation; The data acquisition and analysis device is connected to the temperature sensor, humidity sensor and salinity sensor and is used to collect data from the monitoring device. The data acquisition and analysis device processes the collected data and outputs the change data of moisture content, temperature and salinity.

[0007] Preferably, the rainfall simulation device comprises rainfall output ports, which are symmetrically distributed above the soil column model device, and the external controller is used to control the rainfall to be adjustable within the range of 0-100 mm / h.

[0008] Preferably, the soil column model is cylindrical, with a height of 50-100 cm and a diameter of 10-20 cm. The insulation layer is made of insulation cotton, and the glass cover is made of organic glass.

[0009] Preferably, a double-leaf door is provided on the front of the thermostat, and a wiring hole for passing the sensor data line is reserved on the double-leaf door.

[0010] Preferably, the height of the water trough does not exceed 1 / 6 of the height of the soil column model, and a circular base for placing the soil column model is provided in the middle of the water trough.

[0011] Preferably, the data acquisition and analysis device converts the measured dielectric constant and conductivity according to the following calibration equation: The calibration equation for volumetric water content θv is: θv = a1·Ka + b1 Among them, Ka is the dielectric constant, a1 and b1 are calibration coefficients; The calibration equation for soil salt content S is: S = a2·σb + b2 Among them, σb is the soil volume conductivity, a2 and b2 are calibration coefficients; The calibration coefficients are obtained by the following steps: A1) Measure the dielectric constant Ka and volume conductivity σb in a standard soil sample with known volume moisture content and salt content; A2) Taking the measured dielectric constant Ka as the independent variable and the volumetric water content θv as the dependent variable, the coefficients a1 and b1 are obtained by the least squares fitting method; A3) Taking the measured volume conductivity σb as the independent variable and the salt content S as the dependent variable, the coefficients a2 and b2 are obtained by the least squares fitting method.

[0012] A method for measuring hydrothermal salt migration in a simulated external environment comprises the following steps: S1) Place the test soil sample into the soil column model, and wrap the soil column model with an insulation layer and a glass cover in sequence; S2) placing the assembled soil column model device on the circular base of the water level simulation device, and injecting water at a predetermined water level into the water tank; S3) Install a temperature sensor, a humidity sensor and a salinity sensor at the installation opening of the glass cover; S4) Start the rainfall simulation device and the solar radiation simulation device, and control the rainfall amount, rainfall speed, rainfall duration and the light intensity of the infrared irradiation lamp through an external controller; S5) Use the water-heat-salt migration monitoring device to monitor the changes in moisture, temperature and salt in the soil column model in real time; S6) Use data acquisition and analysis equipment to collect and analyze monitoring data to determine the laws of water, heat and salt migration.

[0013] Preferably, the data analysis in step S6 includes: S61) Calculate the temperature variation with soil column height under specified rainfall and solar radiation conditions; S62) Calculate the change of volumetric water content with soil column height under specified rainfall and solar radiation conditions; S63) Calculate the variation of salt content with soil column height under specified rainfall and solar radiation conditions; S64) Analyze the variation patterns of the above parameters with and without groundwater recharge.

[0014] Preferably, in step S4, the control range of rainfall is 0-100 mm / h, and the radiation intensity of the infrared irradiation lamp is 0-1000 W / m².

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1) This application realizes the comprehensive simulation of multiple external environmental factors by integrating a rainfall simulation device, a solar radiation simulation device and a water level simulation device. This application overcomes the limitation of the prior art that only a single environmental factor can be simulated, making the test conditions closer to the actual engineering environment and improving the reliability and practical value of the test results; 2) This application uses temperature sensors, humidity sensors and salt sensors arranged at equal intervals along the axis of the soil column to achieve real-time monitoring of water, heat and salt changes inside the soil. This non-destructive measurement method avoids the disturbance of the soil structure by traditional sampling methods. At the same time, the dynamic change process of water, heat and salt migration is obtained through continuous monitoring, providing reliable data support for in-depth research on the migration law inside the soil; 3) This application innovatively uses a calibration equation to calculate the salt content. By measuring the dielectric constant and conductivity and combining the calibration coefficient obtained by the least squares method, the indirect measurement of the salt content is achieved. This method not only improves the measurement accuracy, but also realizes real-time monitoring of the salt content, overcomes the disadvantage of the traditional method that requires destructive sampling, and provides the possibility for long-term monitoring; 4) The overall structure of the present application is reasonably designed, each functional module can be independently controlled, and the operation is convenient. Parameters such as rainfall and radiation intensity can be accurately adjusted through an external controller. The equipment is easy to disassemble and assemble, and easy to maintain. At the same time, it has good environmental protection and economy. These characteristics make the present invention not only suitable for scientific research experiments, but also can be promoted and applied to monitoring and analysis in actual engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a front structural cross-sectional view of the present application; Figure 2 This is the front view of the application; Figure 3 A top view of the present application; Figure 4 This is a front view of the glass cover of this application; Figure 5 This is a schematic diagram of the connection between the data acquisition and analysis device of the present application and the hydrothermal salt migration monitoring device; Figure 6 This is a flow chart of the hydrothermal salt migration determination method of the present application.

[0017] In the figure: 1. Rainfall simulation device; 11. Rainfall output port; 2. Solar radiation simulation device; 21. Infrared irradiation lamp; 3. Soil column model device; 31. Soil column model; 32. Insulation layer; 33. Glass cover; 4. Constant temperature box; 41. Double doors; 42. Wiring hole; 5. Water, heat and salt migration monitoring device; 51. Temperature sensor; 52. Humidity sensor; 53. Salt sensor; 6. Water level simulation device; 61. Pushable chassis; 62. Water tank; 63. Round base; 7. Data acquisition and analysis device. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the description of the invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0020] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the description of the invention, it should be noted that the execution order of the steps is not limited by the serial numbers, and the order of some steps can be changed, the steps can be executed simultaneously, the steps can be executed separately, etc., all of which are within the protection scope of this application.

[0022] See also Figure 1-6The present invention provides a technical solution: a water-heat-salt migration test device and method for simulating an external environment, comprising: Constant temperature box 4, used to provide a constant temperature test environment; The rainfall simulation device 1 is arranged on the top of the thermostatic box 4 and is used to simulate the external rainfall environment. The rainfall simulation device 1 controls the rainfall amount, rainfall speed and rainfall duration through an external controller; The soil column model device 3 is arranged inside the constant temperature box 4 and is used to place the test soil sample. The soil column model device 3 is provided with a soil column model 31 as the test soil sample. The outer surface of the soil column model 31 is provided with a heat preservation layer 32. The outer side of the soil column model 31 is provided with a glass cover 33. The solar radiation simulation device 2 is arranged on the top of the constant temperature box 4, and includes at least one group of infrared irradiation lamps 21. The infrared irradiation lamps 21 are symmetrically arranged on both sides of the soil column model device 3. By adjusting the light intensity, irradiation time and radiation angle of the irradiation lamps 21, the temperature gradient of the soil column model 31 in the soil column model device 3 is regulated to simulate the influence of solar radiation on the soil column model 31; The water-heat-salt migration monitoring device 5 is arranged on the glass cover 33, and is used to monitor the distribution and changes of moisture, temperature and salt along the height of the soil column in the soil column model 31 in real time. The water-heat-salt migration monitoring device 5 includes several groups of mounting ports on the glass cover 33, a temperature sensor 51, a humidity sensor 52 and a salt sensor 53. The several groups of mounting ports are arranged at equal intervals along the axis direction of the soil column model 31, and the temperature sensor 51, the humidity sensor 52 and the salt sensor 53 are connected to the several groups of mounting ports; The water level simulation device 6 is arranged at the inner bottom of the thermostatic box 4, and is used to simulate the groundwater level and water replenishment. The water level simulation device 6 includes a push-pull chassis 61 and a water tank 62 arranged on the top of the push-pull chassis 61. The water level in the water tank 62 is adjustable, and is used to simulate the dynamic change of water in the process of groundwater replenishment and evaporation. The data acquisition and analysis device 7 is connected to the temperature sensor 51, the humidity sensor 52 and the salinity sensor 53, and is used to collect data from the monitoring device 5. The data acquisition and analysis device 7 processes the collected data and outputs the change data of moisture content, temperature and salinity.

[0023] Specifically, the device realizes the comprehensive simulation of multiple external environmental factors by integrating a rainfall simulation device 1, a solar radiation simulation device 2 and a water level simulation device 6, overcoming the limitation of the prior art that only a single environmental factor can be simulated, making the test conditions closer to the actual engineering environment and improving the reliability and practical value of the test results.

[0024] Specifically, the soil column model device 3 is placed inside the constant temperature box 4, and a heat preservation layer 32 and a glass cover 33 are provided outside the soil column model device 3, so that the stability of the test environment is effectively guaranteed.

[0025] Specifically, the water, heat and salt migration monitoring device 5 adopts the method of arranging temperature sensors 51, humidity sensors 52 and salt sensors 53 at equal intervals along the axis of the soil column, thereby realizing real-time, non-destructive monitoring of the changes in water, heat and salt inside the soil, overcoming the disturbance problem of traditional sampling methods on the soil structure, and providing reliable data support for in-depth research on the migration laws inside the soil.

[0026] Specifically, the overall structure of the present application is reasonably designed, each functional module can be independently controlled and easy to operate, and parameters such as rainfall and radiation intensity can be accurately adjusted through an external controller. The equipment is easy to disassemble and assemble, and easy to maintain. It also has good environmental protection and economy. These characteristics make the present invention not only suitable for scientific research experiments, but also can be promoted and applied to monitoring and analysis in actual engineering projects.

[0027] The rainfall simulation device 1 includes a rainfall output port 11, which is symmetrically distributed above the soil column model device 3, and an external controller is used to control the rainfall to be adjustable within the range of 0-100 mm / h. Specifically, by setting symmetrically distributed rainfall output ports 11 in the rainfall simulation device 1 and controlling the rainfall to be adjustable within the range of 0-100 mm / h through an external controller, an accurate simulation of the natural rainfall process is achieved. This design not only ensures the uniformity of rainfall distribution, but also can adjust the rainfall intensity according to actual needs, so that the test conditions are closer to the actual engineering environment, and the reliability and practical value of the test results are improved.

[0028] Specifically, the rainfall and solar radiation simulation system is located on the thermostat 4 as a whole, and the rainfall output port 11 and the infrared irradiation lamp 21 are symmetrically distributed to simulate the external rainfall environment as much as possible. The amount of water can be controlled by an external controller to achieve multi-case rainfall simulation. The infrared irradiation lamp 21 can adjust the required target temperature to adjust the light intensity. When the light intensity is high, the soil column heats up quickly and the temperature gradient is large; when the light intensity is low, the soil column heats up slowly and the temperature gradient is small. The rainfall and solar radiation simulation system is controlled by an external controller, specifically including the amount of rainfall, rainfall speed, rainfall duration, radiation intensity, number of radiation lamps, radiation duration, etc. The device is mainly used to simulate the external environment, including rainfall and solar radiation, and provide the soil column test with rainfall infiltration and the temperature difference caused by solar radiation.

[0029] The soil column model 31 is cylindrical, with a height of 50-100 cm and a diameter of 10-20 cm. The insulation layer 32 is made of insulation cotton, and the glass cover 33 is made of organic glass. Specifically, by designing the soil column model 31 into a cylindrical shape of a specific size, and using the insulation layer 32 made of insulation cotton and the glass cover 33 made of organic glass, it is ensured that the test sample is sufficiently representative and a good insulation and observation effect is achieved. This structural design makes the temperature field distribution during the test more uniform, and it is convenient to observe the changes inside the soil.

[0030] Specifically, the soil column model device 3 is located as a whole in a constant temperature box 4, and the lower part is located in a water level simulation device 6. The glass cover 33 is used to fix the soil column model 31. The sensor reserved opening provided on the glass cover 33 facilitates the access of the sensor. Insulation material can be added to the outermost layer of the soil column as an insulation layer 32, and the specific setting is selected according to the needs of the test and simulation conditions.

[0031] Reference Manual Attached Figure 2 The front of the thermostat 4 is provided with a double-leaf door 41, and a wiring hole 42 for passing the sensor data line is reserved on the double-leaf door 41. Specifically, the design of setting the double-leaf door 41 and reserving the wiring hole 42 on the front of the thermostat 4 not only facilitates the installation and maintenance of the equipment and the replacement of soil samples, but also solves the problem of laying the sensor data line, thereby greatly improving the practicality and operational convenience of the device, while ensuring the reliability of the sensor connection. The soil column and water level simulation system are pushed in, which is convenient and fast.

[0032] The height of the water tank 62 does not exceed 1 / 6 of the height of the soil column model 31 , and a circular base 63 for placing the soil column model 31 is provided in the middle of the water tank 62 .

[0033] Specifically, according to actual use requirements, the circular base 63 can be made of hydrophobic, mesh, breathable or other materials.

[0034] Specifically, by controlling the height of the water tank 62 to not exceed 1 / 6 of the height of the soil column model 31 and providing a circular base 63, the rationality of the groundwater level simulation is ensured and stable support is provided, making the groundwater recharge process closer to the natural state, while also facilitating the installation and fixation of the soil column model device.

[0035] The data acquisition and analysis device 7 converts the measured dielectric constant and conductivity according to the following calibration equation: The calibration equation for volumetric water content θv is: θv = a1·Ka + b1 Among them, Ka is the dielectric constant, a1 and b1 are calibration coefficients; The calibration equation for soil salt content S is: S = a2·σb + b2 Among them, σb is the soil volume conductivity, a2 and b2 are calibration coefficients; The calibration coefficients are obtained by the following steps: A1) Measure the dielectric constant Ka and volume conductivity σb in a standard soil sample with known volume moisture content and salt content; A2) Taking the measured dielectric constant Ka as the independent variable and the volumetric water content θv as the dependent variable, the coefficients a1 and b1 are obtained by the least squares fitting method; A3) Taking the measured volume conductivity σb as the independent variable and the salt content S as the dependent variable, the coefficients a2 and b2 are obtained by the least squares fitting method.

[0036] Specifically, this application innovatively uses a calibration equation to calculate the salt content, measures the dielectric constant and conductivity, and obtains the calibration coefficient by fitting with the least squares method, thus realizing indirect measurement of the salt content. This method not only improves the measurement accuracy, but also realizes real-time monitoring of the salt content, overcomes the disadvantage of destructive sampling in traditional methods, and provides the possibility for long-term monitoring.

[0037] A method for measuring hydrothermal salt migration in a simulated external environment comprises the following steps: S1) placing the test soil sample into a soil column model 31, and wrapping the soil column model 31 with a thermal insulation layer 32 and a glass cover 33 in sequence; S2) placing the assembled soil column model device 3 on the circular base 63 of the water level simulation device 6, and injecting water of a predetermined water level into the water tank 62; S3) installing a temperature sensor 51, a humidity sensor 52 and a salt sensor 53 at the installation opening of the glass cover 33; S4) starting the rainfall simulation device 1 and the solar radiation simulation device 2, and controlling the rainfall amount, rainfall speed, rainfall duration and the illumination intensity of the infrared irradiation lamp 21 through an external controller; S5) using the water-heat-salt migration monitoring device 5 to monitor the changes in moisture, temperature and salt in the soil column model 31 in real time; S6) Using the data acquisition and analysis device 7 to collect and analyze the monitoring data, determine the water, heat and salt migration law.

[0038] Specifically, this method achieves full process control from soil sample preparation to data collection and analysis through systematic step design, ensuring the standardization of the test process and the reliability of the data. The standardized operating procedures not only improve the test efficiency, but also make the test results have good repeatability.

[0039] The data analysis in step S6 includes: S61) Calculate the temperature variation with soil column height under specified rainfall and solar radiation conditions; S62) Calculate the change of volumetric water content with soil column height under specified rainfall and solar radiation conditions; S63) Calculate the variation of salt content with soil column height under specified rainfall and solar radiation conditions; S64) Analyze the variation patterns of the above parameters with and without groundwater recharge.

[0040] Specifically, by refining the data analysis steps, a comprehensive analysis of the changes in parameters such as temperature, moisture content, and salt content with the height of the soil column was achieved. The systematic analysis method not only revealed the migration laws of hydrothermal salts in the soil, but also provided a reliable theoretical basis for engineering practice.

[0041] In step S4, the control range of rainfall is 0-100 mm / h, and the radiation intensity of the infrared irradiation lamp 21 is 0-1000 W / m².

[0042] Specifically, by clearly stipulating that the control range of rainfall is 0-100mm / h and the radiation intensity of the infrared lamp 21 is 0-1000W / m², the controllability of the test conditions is ensured and various working conditions that may be encountered in actual projects are met. The setting of these parameter ranges enables the test to simulate a wider range of environmental conditions and improves the applicability of the research results. Example 1

[0043] Taking the underground soil of a construction site as the research object, the water, heat and salt migration law was studied. The specific implementation steps are as follows: S1: Take a soil sample from the surface layer of the site from 0 to 100 cm, pass it through a 2 mm sieve, and place it into a cylindrical soil column model 31 with a height of 80 cm and a diameter of 15 cm. Use the layered compaction method to control the dry density to 1.65 g / cm³. Wrap the soil column model 31 with a 2 cm thick insulation layer 32 made of insulation cotton and a 3 mm thick glass cover 33 made of organic glass. S2: Place the assembled soil column model device 3 on the circular base 63 of the water level simulation device 6, and inject deionized water with a water level of 8 cm into the water tank 62 with a height of 10 cm; S3: An installation opening is set every 10 cm along the height of the soil column on the glass cover 33, and a total of 8 monitoring points are set from the bottom to the top. A temperature sensor 51, a humidity sensor 52 and a salt sensor 53 are installed at each installation opening; S4: Set the rainfall of the rainfall simulation device 1 to 50 mm / h and the rainfall duration to 2 hours; start the infrared irradiation lamp 21 in the solar radiation simulation device 2, set the radiation intensity to 600 W / m² and the irradiation duration to 6 hours; S5: Collect data every 30 minutes using the hydrothermal salt migration monitoring device 5; S6: Use the data acquisition and analysis device 7 to collect and analyze the monitoring data. The calculation process is as follows: First, obtain the calibration coefficient: A1) Select 5 standard soil samples with known volume moisture content (10%, 15%, 20%, 25%, 30%) and 5 standard soil samples with known salt content (0.5%, 1.0%, 1.5%, 2.0%, 2.5%), and measure their dielectric constant Ka and volume conductivity σb; A2) The measured data obtained are as follows: Dielectric constant Ka: 8.5, 12.3, 16.8, 21.5, 26.2 Corresponding volume moisture content θv: 10%, 15%, 20%, 25%, 30% The least squares fitting method yields: a1 = 1.12, b1 = 0.48 A3) Volume conductivity σb: 0.15, 0.32, 0.48, 0.65, 0.82 mS / cm Corresponding salt content S: 0.5%, 1.0%, 1.5%, 2.0%, 2.5% The least squares fitting method yields: a2 = 3.05, b2 = 0.04 Then conduct specific data analysis: S61) After 6 hours of testing, the temperature at 20 cm from the bottom increased from the initial 20°C to 28.5°C; S62) The dielectric constant Ka measured at this position is 18.5, which is substituted into the calibration equation: θv = 1.12 × 18.5 + 0.48 = 21.2% This indicates that the volumetric water content at this location is 21.2%; S63) The volume conductivity σb measured at this position is 0.45 mS / cm, which is substituted into the calibration equation: S = 3.05 × 0.45 + 0.04 = 1.41% It shows that the salt content there is 1.41%; S64) By comparing the situations with and without groundwater recharge, it was found that: When there is groundwater recharge, the water content at the bottom 20 cm increases by 5.8% within 6 hours; Without groundwater recharge, the water content at the bottom 20 cm increased by only 2.3%.

[0044] Therefore, the test results of Example 1 show that under the combined effect of simulated rainfall and solar radiation, the moisture, temperature and salinity in the soil column all show a clear gradient distribution. The presence of groundwater significantly affects the migration rate of moisture, which provides an important reference for the prediction of moisture migration in actual engineering.

[0045] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A water-heat-salt migration test device simulating an external environment, characterized in that: include: A constant temperature box (4), used to provide a constant temperature test environment; A rainfall simulation device (1) is arranged on the top of the constant temperature box (4) and is used to simulate an external rainfall environment. The rainfall simulation device (1) controls the rainfall amount, rainfall speed and rainfall duration through an external controller; A soil column model device (3) is arranged inside the constant temperature box (4) and is used to place a test soil sample. A soil column model (31) is arranged inside the soil column model device (3) as the test soil sample. The outer surface of the soil column model (31) is provided with a heat-insulating layer (32). The outer side of the soil column model (31) is provided with a glass cover (33). A solar radiation simulation device (2) is arranged on the top of the constant temperature box (4), and comprises at least one group of infrared irradiation lamps (21), wherein the infrared irradiation lamps (21) are symmetrically arranged on both sides of the soil column model device (3), and the temperature gradient of the soil column model (31) in the soil column model device (3) is regulated by adjusting the light intensity, irradiation time and radiation angle of the irradiation lamps (21), so as to simulate the influence of solar radiation on the soil column model (31); A water-heat-salt migration monitoring device (5) is arranged on the glass cover (33) and is used to monitor in real time the distribution and changes of moisture, temperature and salt along the height of the soil column in the soil column model (31). The water-heat-salt migration monitoring device (5) comprises a plurality of groups of mounting openings on the glass cover (33), a temperature sensor (51), a humidity sensor (52) and a salt sensor (53). The plurality of groups of mounting openings are arranged at equal intervals along the axis direction of the soil column model (31). The temperature sensor (51), the humidity sensor (52) and the salt sensor (53) are connected to the plurality of groups of mounting openings. A water level simulation device (6) is arranged at the inner bottom of the thermostatic box (4) and is used to simulate the groundwater level and water replenishment. The water level simulation device (6) comprises a push-pull chassis (61) and a water tank (62) arranged on the top of the push-pull chassis (61). The water level in the water tank (62) is adjustable and is used to simulate the dynamic change of water during the groundwater replenishment and evaporation process. A data acquisition and analysis device (7) is connected to the temperature sensor (51), the humidity sensor (52) and the salinity sensor (53) and is used to collect data from the monitoring device (5). The data acquisition and analysis device (7) processes the collected data and outputs data on changes in moisture content, temperature and salinity.

2. The hydrothermal salt migration test device for simulating external environment according to claim 1, characterized in that: The rainfall simulation device (1) comprises rainfall output ports (11), wherein the rainfall output ports (11) are symmetrically distributed above the soil column model device (3), and the external controller is used to control the rainfall to be adjustable within the range of 0-100 mm / h.

3. The hydrothermal salt migration test device for simulating external environment according to claim 1, characterized in that: The soil column model (31) is cylindrical, with a height of 50-100 cm and a diameter of 10-20 cm. The thermal insulation layer (32) is made of thermal insulation cotton, and the glass cover (33) is made of organic glass.

4. The hydrothermal salt migration test device for simulating external environment according to claim 1, characterized in that: The front of the thermostatic box (4) is provided with a double-leaf door (41), and the double-leaf door (41) is provided with a wiring hole (42) for passing the sensor data line.

5. The hydrothermal salt migration test device for simulating external environment according to claim 1, characterized in that: The height of the water trough (62) does not exceed 1 / 6 of the height of the soil column model (31), and a circular base (63) for placing the soil column model (31) is provided in the middle of the water trough (62).

6. The hydrothermal salt migration test device for simulating external environment according to claim 1, characterized in that: The data acquisition and analysis device (7) converts the measured dielectric constant and conductivity according to the following calibration equation: The calibration equation for volumetric water content θv is: θv = a1·Ka + b1 Among them, Ka is the dielectric constant, a1 and b1 are calibration coefficients; The calibration equation for soil salt content S is: S = a2·σb + b2 Among them, σb is the soil volume conductivity, a2 and b2 are calibration coefficients; The calibration coefficients are obtained by the following steps: A1) Measure the dielectric constant Ka and volume conductivity σb in a standard soil sample with known volume moisture content and salt content; A2) Taking the measured dielectric constant Ka as the independent variable and the volumetric water content θv as the dependent variable, the coefficients a1 and b1 are obtained by the least squares fitting method; A3) Taking the measured volume conductivity σb as the independent variable and the salt content S as the dependent variable, the coefficients a2 and b2 are obtained by the least squares fitting method.

7. A method for measuring hydrothermal salt migration in a simulated external environment, characterized in that: The following steps are involved: S1) placing the test soil sample into a soil column model (31), and sequentially wrapping the soil column model (31) with a thermal insulation layer (32) and a glass cover (33); S2) placing the assembled soil column model device (3) on the circular base (63) of the water level simulation device (6), and injecting water of a predetermined water level into the water tank (62); S3) installing a temperature sensor (51), a humidity sensor (52) and a salinity sensor (53) at the installation opening of the glass cover (33); S4) starting the rainfall simulation device (1) and the solar radiation simulation device (2), and controlling the rainfall amount, rainfall speed, rainfall duration and the light intensity of the infrared irradiation lamp (21) through an external controller; S5) using a water-heat-salt migration monitoring device (5) to monitor the changes in water, temperature and salt content in the soil column model (31) in real time; S6) Use the data acquisition and analysis device (7) to collect and analyze the monitoring data to determine the laws of water, heat and salt migration.

8. The method for determining the hydrothermal salt migration in a simulated external environment according to claim 7, characterized in that: The data analysis in step S6 includes: S61) Calculate the temperature variation with soil column height under specified rainfall and solar radiation conditions; S62) Calculate the change of volumetric water content with soil column height under specified rainfall and solar radiation conditions; S63) Calculate the variation of salt content with soil column height under specified rainfall and solar radiation conditions; S64) Analyze the variation patterns of the above parameters with and without groundwater recharge.

9. The method for measuring hydrothermal salt migration in a simulated external environment according to claim 7, characterized in that: In step S4, the control range of rainfall is 0-100 mm / h, and the radiation intensity of the infrared irradiation lamp (21) is 0-1000 W / m².

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