Experimental device and method for simulating transportation of seasonal frozen soil hydrothermal salt

Abstract

The invention discloses an experimental device and method for simulating transportation of seasonal frozen soil hydrothermal salt. The experimental device comprises a water supply simulation system, a soil sample section simulation device, an auxiliary device and a data acquisition and control system which are fixed on a steel structure frame, according to the scheme, through the water supply simulation system, the soil sample profile simulation device, the auxiliary device and the data acquisition and control system, main experimental parameters such as an infiltration water head, underground water level occurrence, freezing and thawing temperature and time, illumination intensity, irrigation amount and the like are monitored and controlled, and the purpose of simulating the outdoor soil environment is achieved; meanwhile, parameters such as moisture, temperature, salinity and conductivity of different layers of the soil are obtained, and then the desalting effect of hydrothermal salt migration and salt-reducing and water-retaining materials in the soil in a single state or multiple combined states of normal freezing, infiltration, evaporation and freeze thawing is evaluated, so that a mode suitable for predicting and controlling soil salinization is selected; powerful technical support is provided for soil water and salt treatment.

Description

Technical Field

[0001] The invention relates to the technical field of soil environment simulation, and in particular to an experimental device and method for simulating the water, heat and salt migration of seasonal frozen soil. Background Art

[0002] In the process of saline soil and water resource utilization in seasonally frozen areas, the salinization process is closely related to the soil water-temperature-salt dynamics. Soil moisture and temperature are the main driving forces for salt migration, and the salt dynamics in the soil are complex and difficult to estimate. Therefore, understanding the soil water-heat-salt dynamics is an important prerequisite for predicting and controlling salinization. It is necessary to test the water and salt migration state in seasonally frozen areas. At present, the test is generally divided into stages of constant freezing, infiltration, evaporation, and freeze-thaw. The sample preparation error is large, time-consuming and labor-intensive, and there are too many uncertain factors in the experimental process, resulting in a low reference value of the test results.

[0003] Therefore, there is an urgent need for an indoor simulation device and method that can simulate the water and salt migration of seasonal frozen soil, and by detecting or controlling the main experimental parameters such as infiltration head, groundwater level, freeze-thaw temperature and time, light intensity, irrigation volume, etc., to qualitatively and quantitatively evaluate the water, heat and salt migration and the desalination effect of salt-reducing and water-retaining materials, so as to select a suitable method for predicting and controlling soil salinization. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides an experimental device and method for simulating the migration of water, heat and salt in seasonal frozen soil, which solves the problem that the existing simulation devices are difficult to achieve single-state simulation and combined-state cyclic simulation of the four states of normal freezing, infiltration, evaporation and freeze-thaw for seasonal frozen soil.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] In a first aspect, an experimental device for simulating the migration of water, heat and salt in seasonal frozen soil is provided, which includes: a soil sample profile simulation device, which includes a base, on which a soil column shell for configuring soil samples is fixedly arranged, the outer side of the soil column shell is wrapped with an insulation layer, and a refrigeration plate is arranged at the upper end of the soil column shell; a water supply simulation system, which includes a static water tank, the static water tank is connected to the water inlet at the upper end of the Martens flask through a peristaltic pump, the water outlet at the lower end of the Martens flask is respectively connected to one end of an upper water inlet pipe and a lower water inlet pipe through a three-way reversing valve, the other ends of the upper water inlet pipe and the lower water inlet pipe are respectively arranged at the upper and lower ends of the soil column shell, and the lower end of the soil column shell is also provided with a static water tank. a drainage pipe connected to a water tank; an auxiliary device, which includes red and ultraviolet lamps for irradiating soil samples, an electric cylinder for adjusting the height of a soil sample profile simulation device, and a synchronous belt module for adjusting the height of a Martens flask; a data acquisition and control system, which includes an electrically connected controller, a touch control console, and an acquisition system, the acquisition system including a number of water level sensors and soil parameter sensors vertically arranged on the soil column shell, a temperature sensor and a light intensity sensor for detecting the temperature and light intensity of the soil sample, a flow meter for detecting the pumping flow, an encoder for detecting the stroke of the synchronous belt module, and scale lines arranged on the soil column shell and the Martens flask.

[0007] Furthermore, a needle water injection cap connected to the upper water inlet pipe is fixedly provided at the upper end of the soil column shell, a number of soil extraction pipes are vertically arranged on the side wall of the soil column shell, a drainage pipe is also provided at the lower end of the soil column shell, and the static water tank includes a clean water tank connected to the peristaltic pump and a seepage tank connected to the drainage pipe.

[0008] Furthermore, the upper water inlet pipe, the lower water inlet pipe, the pipeline between the peristaltic pump and the Malchnitz flask, and the drainage pipe are all flexible pipelines with a surplus length.

[0009] Furthermore, the synchronous belt module includes a moving platform for mounting the Martens flask, and the moving platform is provided with sliders respectively slidably matched with the two vertical guide rails, and the sliders are connected to the servo motor through a synchronous belt.

[0010] Furthermore, the touch control console includes a single setting module and a combination setting module for single selection and combination selection of the four states of soil samples, namely, constant freezing, infiltration, evaporation, and freeze-thaw, a soil parameter setting module, a water supply condition setting module, and an experimental environment parameter setting module.

[0011] In a second aspect, a method for simulating seasonal frozen soil water, heat and salt migration is provided, which comprises the following steps:

[0012] S1: Configure the soil sample in the soil column shell and input the soil sample type into the touch operation console;

[0013] S2: select the four states of soil sample, i.e., constant freezing, infiltration, evaporation, and freeze-thaw, in a single setting module or in a combined setting module, and set a single simulation duration or a combined simulation single cycle duration and the number of cycles;

[0014] S3: According to the simulation requirements of the soil sample for the four states of constant freezing, infiltration, evaporation, and freeze-thaw, the parameters of the four states are set respectively through the soil parameter setting module, the water supply condition setting module, and the experimental environment parameter setting module, including: the fixed head height range is 0-10.0cm, the groundwater level is -1.0-0m, the freeze-thaw temperature is -20-30.0℃, the light intensity parameter is 0-50000lx, the pumping water pressure is 0-0.2MPa, and the frequency is 0-1500 times / min; and the soil sample is subjected to environmental simulation;

[0015] S4: The moisture, temperature and salt content of each layer of soil sample are collected in real time through soil parameter sensors and displayed on the touch operation console;

[0016] S5: Take out 3-5g of soil samples regularly through the soil sampling tube, and measure the content of eight major salt ions and soil pH in the soil samples. After sampling, prepare soil samples with equal water content, salt content and weight and fill them back into the soil column shell;

[0017] S6: After the simulation experiment is completed, the soil samples are extracted in layers by using a soil ring cutter, the particle gradation of each layer of soil samples is dried and screened, and the particle gradation curve of the soil samples is drawn, and the fine particle migration of the soil samples is analyzed;

[0018] S7: After the experiment, the water is drained through the drain pipe at the bottom of the standing water tank, and the soil column shell and the standing water tank are cleaned for the next use.

[0019] Furthermore, in step S1, a salt-reducing and water-retaining material is added to the upper layer of the soil sample, the funnel viscosity of the salt-reducing and water-retaining material is 16-22P, and the salt-reducing and water-retaining material is an organic high molecular polymer solution prepared by mixing a non-ionic polyacrylamide aqueous solution, modified coal gangue powder and crushed straw in proportion at room temperature, and the preparation method thereof comprises the following steps:

[0020] S11. Pre-configured 20% concentration of non-ionic polyacrylamide aqueous solution;

[0021] S12. Add modified coal gangue powder with an improved soil content of 10.0-20.0% and crushed straw with an improved soil content of 1.0-1.5%, and dilute the organic polymer solution to 1.45-1.87%.

[0022] Furthermore, the soil sample type in step S1 includes the type and content of the soil sample, the type of the soil sample includes gravel soil, topsoil, sandy soil and mud, and the content of the soil sample includes the content of clay particles, silt particles and sand particles.

[0023] Furthermore, the simulation method of the four states of constant freezing, infiltration, evaporation, and freeze-thaw of the soil sample in step S3 is:

[0024] S31: when the frozen state and freeze-thaw state simulation is required, step S32 is executed; when the infiltration state simulation is required, step S33 is executed; when the evaporation state simulation is required, step S34 is executed;

[0025] S32: disconnecting the water outlet at the lower end of the Martens flask from the upper water inlet pipe and the lower water inlet pipe through the three-way reversing valve;

[0026] S33: connecting the water outlet at the lower end of the flask with the upper water inlet pipe through a three-way reversing valve;

[0027] S34: Connect the water outlet at the lower end of the flask with the lower water inlet pipe through the three-way reversing valve.

[0028] The beneficial effects of the present invention are:

[0029] 1. This scheme uses a water supply simulation system, a soil sample profile simulation device, auxiliary devices, and a data acquisition and control system to monitor and control the main experimental parameters such as infiltration head, groundwater level, freeze-thaw temperature and time, light intensity, and irrigation volume, so as to achieve the purpose of simulating the outdoor soil environment; at the same time, it obtains parameters such as moisture, temperature, salinity, and electrical conductivity in different soil layers, and then evaluates the water, heat, and salt migration and the desalination effect of salt-reducing and water-retaining materials in the single state or multiple combined states of constant freezing, infiltration, evaporation, and freeze-thaw in the soil, so as to select a method suitable for predicting and controlling soil salinization, and provide strong technical support for soil water and salt management.

[0030] 2. The soil sample profile simulation device of this scheme can simulate the outdoor soil profile. The electric cylinder can raise the height of the soil sample profile simulation device. The insulation layer wraps the soil column shell for insulation. The refrigeration coil in the insulation layer surrounds the unfilled part of the upper part of the soil column shell to realize one-dimensional unidirectional frozen soil surface environment simulation. The temperature of the soil column shell is controlled by the cooperation of the temperature sensor and the refrigerator.

[0031] 3. The water supply simulation system of this scheme cooperates with auxiliary devices to realize the lifting and lowering adjustment of the Malchnitz flask and the soil column shell respectively. The principle of constant water head of the Malchnitz flask is used to realize the regulation of fixed water head under infiltration state and the regulation of groundwater level under evaporation state; the synchronous belt module and the electric cylinder jointly realize the controllable up and down movement of the Malchnitz flask and the soil column shell, the encoder can collect and calculate the height between the Malchnitz flask and the soil column shell, and control the water level of the soil column shell together with the Malchnitz flask, and the water outlet at the lower end of the Malchnitz flask can be selectively connected to the upper water inlet pipe and the lower water inlet pipe through a three-way reversing valve to facilitate the switching of the four simulation states of constant freezing, infiltration, evaporation, and freeze-thaw.

[0032] 4. Two modes of operation interfaces are designed on the touch console of this scheme, including a single setting module and a combined setting module, to realize indoor continuous research on the water, heat and salt migration inside the soil before and after simulating various natural environment changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the experimental device for simulating water, heat and salt migration in seasonal frozen soil.

[0034] Figure 2 It is a structural schematic diagram of the soil sample profile simulation device.

[0035] Figure 3 Schematic diagram of the structure of a Martens flask.

[0036] Figure 4 Schematic diagram of the single experiment mode operation interface.

[0037] Figure 5 Schematic diagram of the combined experiment mode operation interface.

[0038] Among them, 1-steel structure frame; 2-transmission shaft; 3-upper limit sensor; 4-arc toothed synchronous belt; 5-slider; 6-mobile platform; 7-buckle; 8-Marshmallow flask; 9-linear guide; 10-upper water inlet pipe; 11-red and ultraviolet lamps; 12-touch operation table; 13-soil column shell; 14-electric cylinder; 15-encoder; 16-lower limit sensor; 17-arc toothed synchronous belt; 18-coupling; 19-servo motor; 20-reducer; 21-flow meter; 23-light intensity sensor; 24-peristaltic pump; 25-servo motor; 26-lower water inlet pipe; 27-static water tank; 28-drain pipe; 29-refrigerator; 30-universal wheel; 31-upper water inlet switch; 32-needle water filling cover; 33-refrigeration coil; 34-insulation layer; 35-scale line; 36-exhaust chamber; 37-base; 38-plug; 39-temperature sensor; 40-soil sampling pipe; 41-water level sensor; 42-soil parameter sensor; 43-lower water inlet switch; 44-drain switch; 45-water inlet of Martens flask; 46-scale line; 47-water outlet of Martens flask; 48-air guide tube; 49-fixing plate. DETAILED DESCRIPTION

[0039] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0040] like Figures 1 to 3 As shown, the experimental device for simulating seasonal frozen soil water, heat and salt migration of the present scheme includes a water supply simulation system fixed on a steel structure frame 1, a soil sample profile simulation device, auxiliary devices and a data acquisition and control system.

[0041] The soil sample profile simulation device includes a soil column shell 13, a refrigeration plate 33, an insulation layer 34, a refrigerator 29, and a base 37. The insulation layer 34 wraps the soil column shell 13, and a refrigeration plate 33 is arranged in the insulation layer 34. The refrigeration plate 33 surrounds the upper part of the soil column shell 13. The refrigerator 29 is connected to the refrigeration plate 33 through a pipeline, and the base 37 is connected to the soil column shell 13. The soil sample profile simulation device can realize the simulation of outdoor soil profiles. The electric cylinder 14 can increase the height of the soil sample profile simulation device. The insulation layer 34 wraps the soil column shell 13 for insulation. The refrigeration coil 33 in the insulation layer 34 surrounds the upper unfilled part of the soil column shell 13, thereby realizing one-dimensional unidirectional frozen soil surface environment simulation. The temperature of the soil column shell is controlled by the cooperation of the temperature sensor 39 and the refrigerator 29.

[0042] The water supply simulation system includes a stationary water tank 27, a servo motor 25, a peristaltic pump 24, a Martens flask 8, and a three-way reversing valve. The stationary water tank 27 includes a clean water tank connected to the peristaltic pump 24 and a seepage water tank connected to the drain pipe 28. The stationary water tank 27 is connected to the water inlet of the peristaltic pump 24, the Martens flask water inlet 45 is connected to the water outlet of the peristaltic pump 24, the Martens flask water outlet 47 is connected to the three-way reversing valve, the three-way reversing valve is respectively connected to one end of the upper water inlet pipe 10 and the lower water inlet pipe 26, the other ends of the upper water inlet pipe 10 and the lower water inlet pipe 26 are respectively arranged at the upper and lower ends of the soil column shell, the servo motor 25 is transmission-connected to the peristaltic pump 24; the Martens flask 8 is installed on the mobile platform 6 through a fixing plate 49, and an air guide tube 48 is arranged in the Martens flask 8.

[0043] The auxiliary device includes red and ultraviolet lamps 11 for irradiating soil samples, an electric cylinder 14 for adjusting the height of the soil sample profile simulation device and a synchronous belt module for adjusting the height of the Martens flask. The red and ultraviolet lamps 11 and the synchronous belt module are fixed on the steel structure frame 1, the fixed end of the electric cylinder 14 is flange-connected to the steel structure frame 1, the telescopic end of the electric cylinder 14 is flange-connected to the base 37, the electric cylinder 14 and the touch control console 12 are both electrically connected to the PLC controller; the synchronous belt module includes a servo motor 19, a reducer 20, a coupling 18, a transmission shaft 2, an arc toothed synchronous belt 17, a slider 5, a linear guide 9 and a moving platform 6.

[0044] The water supply simulation system can realize water level control during the experiment. The synchronous belt module and the electric cylinder 14 jointly realize the controllable up and down movement of the middle Malchnitz flask 8 and the soil column shell 13. The encoder 15 can collect and calculate the height between the Malchnitz flask 8 and the soil column shell 13, and control the water level of the soil column shell 13 together with the Malchnitz flask 8. The outlet water pipe of the Malchnitz flask 8 can be adjusted to enter the upper and lower water inlet pipes of the soil column through the reversing valve 10 to switch the evaporation and infiltration processes.

[0045] The water supply simulation system of the present scheme cooperates with auxiliary devices to realize the lifting and lowering adjustment of the Malchnitz flask 8 and the soil column shell 13 respectively, and utilizes the principle of constant water head of the Malchnitz flask 8 to realize the regulation of fixed water head under infiltration state and the regulation of groundwater level under evaporation state; wherein the synchronous belt module and the electric cylinder 14 jointly realize the controllable up and down movement of the middle Malchnitz flask and the soil column shell 13, the encoder 15 can collect and calculate the height between the Malchnitz flask 8 and the soil column shell 13, and control the water level of the soil column shell 13 together with the Malchnitz flask 8, and the water outlet at the lower end of the Malchnitz flask 8 can be selectively connected to the upper water inlet pipe 10 and the lower water inlet pipe 26 through a three-way reversing valve to facilitate the switching of the four simulation states of constant freezing, infiltration, evaporation, and freeze-thaw.

[0046] The data acquisition and control system includes an upper limit sensor 3, a lower limit sensor 16, an encoder 15, a flow meter 21, a scale line 35 on the soil column shell and a scale line 46 on the Martens flask, a water level sensor 41, a soil parameter sensor 42, a temperature sensor 39, a light intensity sensor 23, and a touch control console 12. The upper limit sensor 3, the lower limit sensor 16, and the rotary encoder 15 are fixed on the steel structure frame 1, the encoder 15 is connected to the arc toothed synchronous belt 4, the arc toothed synchronous belt 4 is connected to the buckle 7, the buckle 7 is connected to the mobile platform 6, the flow meter 22 is connected to the outlet pipe of the peristaltic pump 24, the water level sensor 41 and the soil parameter sensor 42 are installed through holes on the soil column shell 13, the light intensity sensor 23 is fixed on the steel structure frame 1, the upper limit sensor 3, the lower limit sensor 16, the rotary encoder 15, the flow meter 21, the water level sensor 41, the soil parameter sensor 42, and the light intensity sensor 23 are all electrically connected to the PLC controller to realize programmable control data acquisition and regulation.

[0047] In this solution, when the water level is lower than the set value, the water level sensor 41 responds, and the peristaltic pump 24 pumps water to the Malchnitz flask 8 for water replenishment regulation, and stops the water supply when it reaches the specified position.

[0048] like Figure 4 and Figure 5 As shown, two modes of operation interfaces are displayed on the touch console 12, namely, a single experiment mode operation interface and a combined experiment mode operation interface, which include a single setting module and a combined setting module for single selection and combined selection of the four states of constant freezing, infiltration, evaporation, and freeze-thaw of soil samples, a soil parameter setting module, a water supply condition setting module, and an experimental environment parameter setting module, so as to realize indoor research on the water, heat, and salt migration of the soil before and after various natural environment changes by simulating one device, and realize intelligent regulation of parameters such as water supply conditions and environmental simulation parameters.

[0049] In order to truly simulate the outdoor environment, the investigated soil profile is laid in the soil column before the experiment. In-situ soil or disturbed soil samples can be taken, and the disturbed soil samples are compacted in layers according to the maximum dry density; from top to bottom, there are 25 cm of sodium alkaline soil and 25 cm of basalt waste from the spoil yard. The sodium alkaline soil is dried and passed through a 2 mm sieve, and the basalt waste is passed through a 2 cm sieve. From bottom to top, the interlayer is scraped every 5 cm, and the soil is laid in layers in the soil column shell 13.

[0050] This scheme provides a method for simulating seasonal frozen soil water, heat and salt migration, which includes the following steps:

[0051] S1: placing a soil sample in the soil column housing 13 and inputting the soil sample type into the touch control console 12;

[0052] S2: select the four states of soil sample, i.e., constant freezing, infiltration, evaporation, and freeze-thaw, in a single setting module or in a combined setting module, and set a single simulation duration or a combined simulation single cycle duration and the number of cycles;

[0053] S3: According to the simulation requirements of the soil sample for the four states of constant freezing, infiltration, evaporation, and freeze-thaw, the parameters of the four states are set respectively through the soil parameter setting module, the water supply condition setting module, and the experimental environment parameter setting module, including: the fixed head height range is 0-10.0cm, the groundwater level is -1.0-0m, the freeze-thaw temperature is -20-30.0℃, the light intensity parameter is 0-50000lx, the pumping water pressure is 0-0.2MPa, and the frequency is 0-1500 times / min; and the soil sample is subjected to environmental simulation;

[0054] S4: The moisture, temperature and salt content of each layer of soil sample are collected in real time through the soil parameter sensor 42 and displayed on the touch control console 12;

[0055] S5: regularly taking out 3-5g of soil samples through the soil sampling tube 40, and measuring the contents of eight major salt ions and soil pH in the soil samples, and after sampling, preparing soil samples with equal water content, salt content and weight and refilling them into the soil column shell;

[0056] S6: After the simulation experiment is completed, the soil samples are extracted in layers by using a soil ring cutter, the particle gradation of each layer of soil samples is dried and screened, and the particle gradation curve of the soil samples is drawn, and the fine particle migration of the soil samples is analyzed;

[0057] S7: After the experiment is over, the water is drained through the drain pipe 28 at the bottom of the static water tank 27, and the soil column shell 13 and the static water tank 27 are cleaned for next use.

[0058] During specific implementation, the type of soil is input into the touch control console 12, and gravel soil, topsoil, sand and mud are selected, and the content of clay, silt and sand is input, and samples can be taken from the field; the relative height of the Martens flask 8 and the soil column shell 13 is jointly controlled by the synchronous belt module and the electric cylinder 14, and the water flow direction is controlled by the three-way reversing valve; the infiltration head is set according to the experimental requirements, and the peristaltic pump 24, the flow meter 21, the Martens flask 8, the three-way reversing valve, the water level sensor 41 and the PLC controller are electrically connected to jointly regulate the water head and groundwater level during the infiltration and evaporation process.

[0059] From the experimental point of view, the relative height difference between the outlet 47 and the base 37 of the Malchnitz flask can be adjusted between -1.0m and 1.5m; according to the requirements of field condition simulation, the main water and environmental simulation parameters are designed as follows: head height range 0-10.0cm, groundwater level -1.0-0m, freeze-thaw temperature -20-0-30.0℃, light intensity parameter 0-50000lx; pumped water should meet fine regulation, and the pumping water pressure meets the pumping height according to the maximum height of the Malchnitz flask 8, and the pumping water pressure is required to be 0-0.2MPa. The pumping water volume should meet the principle of multiple small amounts. The faster the water replenishment speed, the greater the pumping frequency, which should not be lower than the frequency of 0-1500 times / min; the pumping volume range should not be lower than 0-15L / min; the temperature in the soil column is jointly controlled by the room temperature, the refrigeration coil 33, and the insulation layer 34, the refrigeration temperature is between 0 and -20℃, and the room temperature is regulated by the indoor air-conditioned room at 0-30℃.

[0060] The simulation method of this scheme is used to study the soil water, heat and salt migration under single and combined modes of infiltration, freeze-thaw and evaporation, and the performance of saline soil salt reduction and water conservation materials. By detecting and controlling the main experimental parameters such as infiltration head, groundwater level, freeze-thaw temperature and time, light intensity, and irrigation volume, the purpose of simulating the outdoor soil environment is achieved, and the parameters such as moisture, temperature, salinity, and electrical conductivity in different soil layers are obtained, and then the water, heat and salt migration and the desalination effect of salt reduction and water conservation materials are evaluated, so as to select a suitable method for predicting and controlling soil salinization.

[0061] In step S1, a salt-reducing and water-retaining material is added to the upper layer of the soil sample, the funnel viscosity of the salt-reducing and water-retaining material is 16-22P, and the salt-reducing and water-retaining material is an organic high molecular polymer solution mixed in proportion at room temperature with a non-ionic polyacrylamide aqueous solution, modified coal gangue powder and crushed straw. The preparation method thereof comprises the following steps:

[0062] S11. Pre-configured 20% concentration of non-ionic polyacrylamide aqueous solution;

[0063] S12. Add modified coal gangue powder with an improved soil content of 10.0-20.0% and crushed straw with an improved soil content of 1.0-1.5%, and dilute the organic polymer solution to 1.45-1.87%.

[0064] Among them, non-ionic polyacrylamide aqueous solution can improve soil structure, retain water, reduce soil bulk density, and increase soil aggregates. Modified coal gangue powder can adjust soil pH and regulate the rheology of the material. Crushed straw can improve soil structure, loosen the soil, and reduce salt.

[0065] The simulation method of the four states of soil sample in step S3, namely, constant freezing, infiltration, evaporation, and freeze-thaw, is as follows:

[0066] S31: when the frozen state and freeze-thaw state simulation is required, step S32 is executed; when the infiltration state simulation is required, step S33 is executed; when the evaporation state simulation is required, step S34 is executed;

[0067] S32: disconnecting the water outlet at the lower end of the Martens flask from the upper water inlet pipe and the lower water inlet pipe through the three-way reversing valve;

[0068] S33: connecting the water outlet at the lower end of the flask to the upper water inlet pipe through the three-way reversing valve, and turning on the upper water inlet switch 31;

[0069] S34: connect the water outlet at the lower end of the flask to the lower water inlet pipe through the three-way reversing valve, and turn on the lower water inlet switch 43.

[0070] In summary, the present invention has a simple structure and reliable operation, can accurately obtain experimental data, can adjust parameters such as infiltration head, groundwater level, freeze-thaw temperature and time, light intensity, etc. as needed, and data such as irrigation amount, wetting front, soil moisture content, soil exchangeable salt ion content, pH, etc. can be collected and regulated, thereby realizing intelligent simulation control.

Claims

1. An experimental device for simulating seasonal frozen soil water, heat and salt migration, characterized in that: include: A soil sample profile simulation device comprises a base, on which a soil column shell for configuring soil samples is fixedly arranged, the outer side of the soil column shell is wrapped with a heat preservation layer, and a refrigeration plate is arranged at the upper end of the soil column shell; A water supply simulation system, comprising a stationary water tank, wherein the stationary water tank is connected to a water inlet at the upper end of a Martens flask through a peristaltic pump, and a water outlet at the lower end of the Martens flask is respectively connected to one end of an upper water inlet pipe and a lower water inlet pipe through a three-way reversing valve, and the other ends of the upper water inlet pipe and the lower water inlet pipe are respectively arranged at the upper and lower ends of a soil column shell, and a drainage pipe connected to the stationary water tank is also arranged at the lower end of the soil column shell; Auxiliary devices, including red and ultraviolet lamps for irradiating soil samples, electric cylinders for adjusting the height of the soil sample profile simulation device, and a synchronous belt module for adjusting the height of the Martens flask; A data acquisition and control system, comprising an electrically connected controller, a touch control console and an acquisition system, wherein the acquisition system comprises a plurality of water level sensors and soil parameter sensors arranged vertically on a soil column shell, a temperature sensor and a light intensity sensor for detecting soil sample temperature and light intensity, a flow meter for detecting pumping flow, an encoder for detecting the travel of a synchronous belt module, and scale lines arranged on the soil column shell and a Martens flask.

2. The experimental device for simulating seasonal frozen soil water, heat and salt migration according to claim 1, characterized in that: A needle water injection cap connected to an upper water inlet pipe is fixedly provided at the upper end of the soil column shell, a plurality of soil extraction pipes are vertically arranged on the side wall of the soil column shell, a drainage pipe is also provided at the lower end of the soil column shell, and the static water tank includes a clean water tank connected to a peristaltic pump and a seepage water tank connected to a drainage pipe.

3. The experimental device for simulating seasonal frozen soil water, heat and salt migration according to claim 1, characterized in that: The upper water inlet pipe, the lower water inlet pipe, the pipeline between the peristaltic pump and the Malvern flask, and the drainage pipe are all flexible pipelines with a surplus length.

4. The experimental device for simulating seasonal frozen soil water, heat and salt migration according to claim 1, characterized in that: The synchronous belt module comprises a mobile platform for mounting the Martens flask, on which a slider which is respectively slidably matched with two vertical guide rails is arranged, and the slider is transmission-connected with the servo motor via a synchronous belt.

5. The experimental device for simulating seasonal frozen soil water, heat and salt migration according to claim 1, characterized in that: The touch control console includes a single setting module and a combined setting module for performing single selection and combined selection of the four states of soil samples, namely, constant freezing, infiltration, evaporation, and freeze-thaw, a soil parameter setting module, a water supply condition setting module, and an experimental environment parameter setting module.

6. A method for simulating seasonal frozen soil water, heat and salt migration, based on the experimental device for simulating seasonal frozen soil water, heat and salt migration according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Configure the soil sample in the soil column shell and input the soil sample type into the touch operation console; S2: select the four states of soil sample, i.e., constant freezing, infiltration, evaporation, and freeze-thaw, in a single setting module or in a combined setting module, and set a single simulation duration or a combined simulation single cycle duration and the number of cycles; S3: According to the simulation requirements of the soil sample for the four states of constant freezing, infiltration, evaporation, and freeze-thaw, the parameters of the four states are set respectively through the soil parameter setting module, the water supply condition setting module, and the experimental environment parameter setting module, including: the fixed head height range is 0-10.0cm, the groundwater level is -1.0-0m, the freeze-thaw temperature is -20-30.0℃, the light intensity parameter is 0-50000lx, the pumping water pressure is 0-0.2MPa, and the frequency is 0-1500 times / min; and the soil sample is subjected to environmental simulation; S4: The moisture, temperature and salt content of each layer of soil sample are collected in real time through soil parameter sensors and displayed on the touch operation console; S5: Take out 3-5g of soil samples regularly through the soil sampling tube, and measure the content of eight major salt ions and soil pH in the soil samples. After sampling, prepare soil samples with equal water content, salt content and weight and fill them back into the soil column shell; S6: After the simulation experiment is completed, the soil samples are extracted in layers by using a soil ring cutter, the particle gradation of each layer of soil samples is dried and screened, and the particle gradation curve of the soil samples is drawn, and the fine particle migration of the soil samples is analyzed; S7: After the experiment, the water is drained through the drain pipe at the bottom of the standing water tank, and the soil column shell and the standing water tank are cleaned for the next use.

7. The method for simulating seasonal frozen soil water, heat and salt migration according to claim 6, characterized in that: In step S1, a salt-reducing and water-retaining material is added to the upper layer of the soil sample, the funnel viscosity of the salt-reducing and water-retaining material is 16-22P, and the salt-reducing and water-retaining material is an organic high molecular polymer solution mixed in proportion at room temperature with a non-ionic polyacrylamide aqueous solution, modified coal gangue powder and crushed straw. The preparation method thereof comprises the following steps: S11. Pre-configured 20% concentration of non-ionic polyacrylamide aqueous solution; S12. Add modified coal gangue powder with an improved soil content of 10.0-20.0% and crushed straw with an improved soil content of 1.0-1.5%, and dilute the organic polymer solution to 1.45-1.87%.

8. The method for simulating seasonal frozen soil water, heat and salt migration according to claim 6, characterized in that: In step S1, the soil sample type includes the type and content of the soil sample. The type of the soil sample includes gravel soil, topsoil, sandy soil and mud. The content of the soil sample includes the content of clay particles, silt particles and sand particles.

9. The method for simulating seasonal frozen soil water, heat and salt migration according to claim 6, characterized in that: The simulation method of the four states of soil sample in step S3, namely, constant freezing, infiltration, evaporation, and freeze-thaw, is as follows: S31: When the frozen state and freeze-thaw state simulation is required, step S32 is executed; when the infiltration state simulation is required, step S33 is executed; when the evaporation state simulation is required, step S34 is executed; S32: disconnecting the water outlet at the lower end of the Martens flask from the upper water inlet pipe and the lower water inlet pipe through the three-way reversing valve; S33: connecting the water outlet at the lower end of the flask with the upper water inlet pipe through a three-way reversing valve; S34: connect the water outlet at the lower end of the flask with the lower water inlet pipe through the three-way reversing valve.

Images