Temperature-controlled soil water retention-shrinkage curve combined testing device and method

Abstract

The present invention belongs to the technical field of unsaturated soil testing, and in particular relates to a temperature-controlled soil water retention and shrinkage curve combined testing device and method thereof, comprising a pressure chamber, the pressure chamber being sealed, the pressure chamber being externally connected to a water bath mechanism and a monitoring mechanism, the water bath mechanism being used to control the temperature inside the pressure chamber, the monitoring mechanism being used to observe changes in soil samples inside the pressure chamber, the pressure chamber being connected to an air supply system, a humidity control system, a flushing system, and a liquid collection system, the air supply system providing test pressure for the soil samples inside the pressure chamber, the humidity control system providing test humidity for the soil samples inside the pressure chamber, the flushing system removing bubbles from the base of the pressure chamber and providing test water for the soil samples inside the pressure chamber, and the liquid collection system collecting and measuring drainage of the soil samples inside the pressure chamber. The present application can obtain the water retention and shrinkage curves of soil in different temperature and humidity environments, effectively reducing errors during the test process without disturbing the soil, and improving test efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of unsaturated soil testing, and in particular relates to a temperature-controlled soil water retention-shrinkage curve combined testing device and method. Background Art

[0002] In recent years, global climate change has been extremely abnormal. Extreme climate events such as continuous heavy rainfall or prolonged droughts have occurred with increasing frequency, leading to frequent major geological and engineering disasters. In fact, both rainfall and drought directly alter the moisture content of the soil. As the soil absorbs or loses water during rainfall or drought, the moisture field redistributes, significantly altering the soil's physical, chemical, hydraulic, and mechanical properties, leading to a series of engineering and environmental geological problems such as landslides and soil cracking. Measuring soil water retention and shrinkage curves is fundamental to analyzing unsaturated processes and changes in the unsaturated zone. Existing testing equipment can only produce a single curve, and separate testing is required for low and high suction phases. This fails to account for real-world temperature and humidity variations, nor can it simultaneously obtain water retention and shrinkage characteristic curves across a wide suction range. This significantly restricts the study of the hydraulic behavior of unsaturated soils. Therefore, a temperature-controlled combined soil water retention and shrinkage curve testing device and method that can effectively improve test accuracy is urgently needed. Summary of the Invention

[0003] The purpose of the present invention is to provide a temperature-controlled soil water retention-shrinkage curve combined testing device and method to solve the above problems, achieve the purpose of integrated testing of soil water retention and shrinkage curve, and improve test accuracy.

[0004] To achieve the above-mentioned purpose, the present invention provides the following scheme: a temperature-controlled soil water retention-shrinkage curve combined testing device, comprising a pressure chamber, which is sealed and connected to a water bath mechanism and a monitoring mechanism. The water bath mechanism is used to control the temperature inside the pressure chamber, and the monitoring mechanism is used to observe changes in soil samples in the pressure chamber. The pressure chamber is connected to an air supply system, a humidity control system, a flushing system and a liquid collection system. The air supply system provides test pressure for the soil sample in the pressure chamber, the humidity control system provides test humidity for the soil sample in the pressure chamber, the flushing system removes bubbles from the base of the pressure chamber and provides test water for the soil sample in the pressure chamber, and the liquid collection system is used to collect and measure drainage of the soil sample in the pressure chamber.

[0005] Preferably, the air supply system includes an air compressor, which is connected to the pressure chamber through a first connecting pipe, and a first valve and a digital pressure gauge are connected to the connecting pipe. The pressure regulating unit is used to regulate the air pressure in the pressure chamber.

[0006] Preferably, the humidity control system includes an air compressor and a humidity regulating unit. The outlet end of the air compressor is connected to the humidity regulating unit. The humidity regulating unit is connected to the pressure chamber through a third connecting pipe. The connecting pipe is connected to a first temperature and humidity sensor and a digital pressure gauge. The humidity regulating unit is used to adjust the air humidity in the pressure chamber.

[0007] Preferably, the humidity regulating unit includes a humidifier and a dryer, and a flow meter and a third valve are connected in sequence between the inlet end of the humidifier and the air compressor, and between the inlet end of the dryer and the air compressor, and the outlet ends of the humidifier and the dryer are connected to the third connecting pipe.

[0008] Preferably, the flushing system includes a clay plate, a glass tube level gauge and a micro vacuum pump. The clay plate is placed at the inner bottom of the pressure chamber. Glass tube level gauges are respectively connected to both sides of the pressure chamber. The bottom outlets of the two groups of glass tube level gauges are respectively connected to the bottom of the clay plate. The inlet end of the micro vacuum pump is connected to the pressure chamber through a second connecting pipe. A fourth valve is provided on the connecting pipe to control the opening and closing of the micro vacuum pump.

[0009] Preferably, the liquid collecting system includes a liquid collecting bottle and a balance. The liquid collecting bottle is connected to the bottom of the pressure chamber through a second connecting pipe. The inlet end of the liquid collecting bottle is connected to a second valve. A balance is placed below the liquid collecting bottle.

[0010] Preferably, the water bath mechanism includes a temperature control chamber, which is arranged on the outside of the pressure chamber and is connected to a constant temperature water bath.

[0011] Preferably, the monitoring mechanism includes a fixed truss, a camera is fixedly connected to the top of the fixed truss, the camera is located above the pressure chamber, laser rangefinders are fixedly connected to both sides of the fixed truss, observation holes are symmetrically opened on both sides of the temperature control chamber, two groups of laser rangefinders are arranged corresponding to the pressure chamber through the two groups of observation holes, and a light source is connected to the top of the inner side of the pressure chamber.

[0012] Preferably, a porous plate is connected to the inner wall of the pressure chamber, and a weighing sensor is connected to the porous plate. The weighing sensor is used to detect the mass change of the soil sample on the porous plate. A second temperature and humidity sensor is also connected to the inner wall of the pressure chamber to monitor the ambient temperature and humidity in the pressure chamber.

[0013] The temperature-controlled soil water retention-shrinkage curve combined testing method is applied to the temperature-controlled soil water retention-shrinkage curve combined testing device, and includes the following steps:

[0014] S1. Connecting the air supply system, humidity control system, pressure chamber, water bath mechanism, and monitoring mechanism, adjusting the temperature and humidity in the pressure chamber through the water bath mechanism and humidity control system, observing the changes in the soil sample on the porous plate through the monitoring mechanism, and obtaining the soil shrinkage curve based on the changes in the volume and mass of the soil sample;

[0015] S2, low suction stage: connect the air supply system, pressure chamber, water bath mechanism, flushing system and liquid collection system, start low-pressure dehumidification, observe the change of soil sample volume on the clay plate in the pressure chamber through the monitoring mechanism, and measure the change of soil mass through the liquid collection system to obtain the water retention curve of the soil within the low suction range;

[0016] S3, high suction stage, connect the air supply system, humidity control system, pressure chamber, water bath mechanism and monitoring system, start dehumidification under high suction, observe the mass and volume changes of the soil sample on the porous plate in the pressure chamber through the monitoring mechanism, and obtain the water retention curve of the soil within the high suction range;

[0017] S4. Summarize the soil water retention-shrinkage curves of the above three stages.

[0018] The present invention has the following technical effects: the main function of the water bath mechanism is to adjust the temperature inside the pressure chamber so that the soil sample is in a temperature-stable environment; the main function of the air supply system is to deliver air of a certain pressure into the pressure chamber, so that the soil sample can be tested under low suction conditions; the main function of the humidity control system is to cooperate with the air supply system to deliver air of a certain humidity into the pressure chamber, so that the soil sample can be tested in different humidity environments; the main function of the flushing system is to remove bubbles from the base of the pressure chamber and provide test water for the soil sample on the clay plate in the pressure chamber during the moisture absorption process; the main function of the liquid collection system is to collect and measure the drainage of the soil sample during the dehumidification process in the low suction section, and connect it to the outside air in a timely manner; the main function of the monitoring mechanism is to obtain the change process of the soil sample under the test state. Overall, the present application can obtain the water holding and shrinkage curves of the soil under different temperature environments, effectively improve the test efficiency, and effectively reduce the error in the test process without disturbing the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a connection diagram of the overall testing device of the present invention;

[0021] Figure 2 Schematic diagram of the water bath mechanism of the present invention;

[0022] Figure 3 This is a schematic diagram of the shrinkage curve test of the present invention;

[0023] Figure 4 This is a schematic diagram of the water retention curve test in a wide suction range of the present invention;

[0024] Among them, 1. air compressor; 2. flow meter; 3. humidifier; 4. dryer; 5. first temperature and humidity sensor; 6. digital pressure gauge; 7. fixed truss; 8. constant temperature water bath; 9. temperature control chamber; 10. pressure chamber; 11. light source; 12. second temperature and humidity sensor; 13. weighing sensor; 14. porous plate; 15. clay plate; 16. camera; 17. laser rangefinder; 18. observation hole; 19. liquid collecting bottle; 20. computer; 21. glass tube liquid level gauge; 22. miniature vacuum pump; 23. balance; 24. first valve; 25. second valve; 26. third valve; 27. fourth valve; 28. first connecting pipe; 29. second connecting pipe; 30. third connecting pipe. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Reference Figure 1-4 As shown, the present invention provides a temperature-controlled soil water retention-shrinkage curve combined testing device, including a pressure chamber 10, which is sealed inside. A water bath mechanism and a monitoring mechanism are connected to the pressure chamber 10. The water bath mechanism is used to control the internal temperature of the pressure chamber 10, and the monitoring mechanism is used to observe the changes in the soil sample in the pressure chamber 10. The pressure chamber 10 is connected to an air supply system, a humidity control system, a flushing system and a liquid collection system. The air supply system provides test pressure for the soil sample in the pressure chamber 10, the humidity control system provides test humidity for the soil sample in the pressure chamber 10, the flushing system removes bubbles for the base in the pressure chamber 10 and provides test water for the soil sample in the pressure chamber 10, and the liquid collection system is used to collect and measure drainage of the soil sample in the pressure chamber 10.

[0028] The main function of the water bath mechanism is to adjust the internal temperature of the pressure chamber 10 so that the soil sample is in a temperature-stable environment; the main function of the air supply system is to deliver air of a certain pressure into the pressure chamber 10, so that the soil sample can be tested in different air pressures; the main function of the humidity control system is to cooperate with the air supply system to deliver air of a certain humidity into the pressure chamber 10, so that the soil sample can be tested in different humidity environments; the main function of the flushing system is to remove bubbles from the base of the pressure chamber 10 and provide test water for the soil sample on the clay plate in the pressure chamber 10 during the moisture absorption process; the main function of the liquid collection system is to collect and measure the drainage of the soil sample during the dehumidification process in the low suction section, and to connect it to the outside air in a timely manner; the main function of the monitoring mechanism is to obtain the change process of the soil sample under the test state. Overall, the present application can obtain the water holding and shrinkage curves of the soil under different temperature environments, effectively improve the test efficiency, and effectively reduce the error in the test process without disturbing the soil.

[0029] According to a further optimized solution, the air supply system includes an air compressor 1 , which is connected to the pressure chamber 10 through a first connecting pipe 28 , and a first valve 24 and a digital pressure gauge 6 are connected to the connecting pipe.

[0030] The air pressure in the pressure chamber 10 is adjusted by the air compressor 1 , and the pressure range provided by the air compressor 1 is 0-1500 kPa.

[0031] To further optimize the solution, the humidity control system includes an air compressor 1 and a humidity control unit. The outlet of the air compressor 1 is connected to the humidity control unit. The humidity control unit is connected to the pressure chamber 10 through a third connecting pipe 30. The connecting pipe is connected to a first temperature and humidity sensor 5 and a digital pressure gauge 6. The humidity control unit is used to adjust the air humidity in the pressure chamber 10, and the first temperature and humidity sensor 5 is used to monitor the air humidity coming out of the humidity control unit.

[0032] The humidity control unit includes a humidifier 3 and a dryer 4. A flow meter 2 and a third valve 26 are connected in sequence between the inlet end of the humidifier 3 and the air compressor 1, and between the inlet end of the dryer 4 and the air compressor 1. The outlet ends of the humidifier 3 and the dryer 4 are connected to the third connecting pipe 30.

[0033] The ratio of air passing through the humidifier 3 and the dryer 4 is controlled by the flow meter 2, so that air entering the pressure chamber 10 with a certain humidity requirement is obtained.

[0034] To further optimize the solution, the flushing system includes a clay plate 15, a glass tube liquid level gauge 21 and a micro vacuum pump 22. The clay plate 15 is placed at the inner bottom of the pressure chamber 10. Glass tube liquid level gauges 21 are connected to both sides of the pressure chamber 10. The bottom outlets of the two sets of glass tube liquid level gauges 21 are respectively connected to the bottom of the clay plate 15. The inlet end of the micro vacuum pump 22 is connected to the inner bottom of the pressure chamber 10 through a second connecting pipe 29. A fourth valve 27 is provided on the connecting pipe to control the opening and closing of the micro vacuum pump 22.

[0035] The glass tube level gauge 21 is used to flush the residual bubbles in the bottom of the inner side of the pressure chamber 10 and the pipeline, and the glass tube level gauge 21 can also be used to replenish the moisture required by the soil sample on the clay plate 15 during the moisture absorption process.

[0036] The water in the base of the pressure chamber 10 and the clay plate 15 can be drained by the micro vacuum pump 22 to avoid damage to the clay plate 15 during the water retention curve test in the high suction stage.

[0037] To further optimize the solution, the liquid collecting system includes a liquid collecting bottle 19 and a balance 23. The liquid collecting bottle 19 is connected to the bottom of the pressure chamber 10 through a second connecting pipe 29. The inlet end of the liquid collecting bottle 19 is connected to a second valve 25. A balance 23 is placed under the liquid collecting bottle 19.

[0038] The liquid collecting system can be used to measure the change in the mass of the soil sample without disturbing the soil sample on the clay plate 15 .

[0039] Through the liquid collecting bottle 19, the atmosphere can be connected in time to effectively protect the equipment.

[0040] According to a further optimization scheme, the water bath mechanism includes a temperature control chamber 9 , which is fitted on the outside of the pressure chamber 10 , and is connected to a constant temperature water bath 8 .

[0041] The water bath mechanism provides more accurate testing conditions than the traditional room temperature test, effectively improving the testing accuracy of the soil.

[0042] To further optimize the solution, the monitoring mechanism includes a fixed truss 7, a camera 16 is fixedly connected to the top of the fixed truss 7, the camera 16 is located above the pressure chamber 10, laser rangefinders 17 are fixedly connected to both sides of the fixed truss 7, observation holes 18 are symmetrically opened on both sides of the temperature control chamber 9, two groups of laser rangefinders 17 are arranged corresponding to the pressure chamber 10 through the two groups of observation holes 18, and a light source 11 is connected to the top inside the pressure chamber 10.

[0043] To further optimize the solution, a porous plate 14 is connected to the inner wall of the pressure chamber 10, and a weighing sensor 13 is connected to the porous plate 14. The weighing sensor 13 is used to detect the mass change of the porous plate 14. A second temperature and humidity sensor 12 is also connected to the inner wall of the pressure chamber 10 to monitor the ambient temperature and humidity in the pressure chamber 10.

[0044] The temperature-controlled soil water retention-shrinkage curve combined test method is applied to a temperature-controlled soil water retention-shrinkage curve combined test device, and includes the following steps:

[0045] S1. Connecting the air supply system, humidity control system, pressure chamber 10, water bath mechanism, and monitoring mechanism. Regulating the temperature and humidity in pressure chamber 10 through the water bath mechanism and humidity control system. Observing the changes in the soil sample on the porous plate through the monitoring mechanism. Obtaining the shrinkage curve of the soil based on the changes in the volume and mass of the soil sample.

[0046] Specifically, first, a saturated soil sample is placed on the porous plate 14, then the light source 11, the camera 16 and the two sets of laser rangefinders 17 are turned on to monitor the volume change process of the soil sample, the second temperature and humidity sensor 12 is turned on to monitor the ambient temperature and humidity in the pressure chamber 10, and the mass change of the soil sample is detected by the weighing sensor 13, the water bath mechanism is turned on, the air compressor 1 is started, and the liquid collecting bottle 19 is connected to the atmosphere, and then the flow meter and the third valve 26 on the passage of the humidifier 3 and the dryer 4 are adjusted respectively to adjust the ratio between dry air and moist air, and adjust the air humidity from high to low, and then the data of all the above steps are recorded by a computer, so that the shrinkage curve of the soil at different temperatures can be obtained without disturbing the soil.

[0047] S2, low suction stage, connect the air supply system, pressure chamber 10, water bath mechanism, flushing system and liquid collection system, start low-pressure dehumidification, observe the change of soil sample volume on the clay plate in the pressure chamber 10 through the monitoring mechanism, measure the change of soil mass through the liquid collection system, and obtain the water retention curve of the soil within the low suction range;

[0048] Specifically, a saturated soil sample is placed on a saturated clay plate 15 at the bottom inner side of the pressure chamber 10, and then the light source 11, the camera 16, and the two sets of laser rangefinders 17 are turned on. The laser rangefinder 17 is lowered to be flush with the surface of the clay plate 15 to monitor the volume change process of the soil sample. The water bath mechanism is turned on, and the second temperature and humidity sensor 12 is turned on to monitor the ambient temperature in the pressure chamber 10. A certain pressure of gas is introduced into the pressure chamber 10 through the air compressor 1. At this time, the pressure chamber 10 is not connected to the humidifier 3 and the dryer 4. The two sets of glass tube liquid level gauges 21 are connected to the clay plate 15. The second valve 25 is opened to connect the liquid collecting bottle 19 to the pressure chamber 1 through the second connecting pipe 29. 0 bottom, control the air pressure in the pressure chamber 10 to increase step by step from 0kPa to 1500kPa. This process is the dehumidification stage, allowing the water in the soil to be discharged into the liquid collecting bottle 19 through the clay plate 15, and the change in the mass of the soil sample under each level of suction is recorded by the balance 23; close the second valve 25, control the air pressure in the pressure chamber 10 to decrease step by step from 1500kPa to 0kPa. This is the moisture absorption stage. The water absorbed by the soil comes from the two sets of glass tube liquid levels 21. The change in the mass of the soil sample under each level of suction is measured by the falling water level height of the two sets of glass tube liquid level gauges 21, thereby obtaining the dehumidification and moisture absorption water retention curves of the soil in the low suction section at different temperatures.

[0049] S3, high suction stage, connecting the air supply system, humidity control system, pressure chamber 10, water bath mechanism and monitoring system, starting dehumidification under high suction, observing the mass and volume changes of the soil sample on the porous plate 14 in the pressure chamber 10 through the monitoring mechanism, and obtaining the water retention curve of the soil within the high suction range;

[0050] Specifically, first, after step S2, the micro vacuum pump 22 is started, the second valve 25 of the liquid collecting bottle 19 and the two sets of glass tube liquid level gauges 21 are closed, and the water in the base of the pressure chamber 10 and the clay plate 15 is drained by the micro vacuum pump 22 to prevent the clay plate 15 from being damaged in the high suction section; after the water in the base of the pressure chamber 10 and the clay plate 15 is drained, the micro vacuum pump 22 is turned off, the second valve 25 of the liquid collecting bottle 19 is opened and the liquid collecting bottle 19 is connected to the atmosphere, and the soil sample tested (or dried) in step S2 is placed on the porous plate 14, and the soil sample is monitored by the weighing sensor 13. To monitor the volume change of the soil sample, turn on the light source 11, camera 16 and two sets of laser rangefinders 17, monitor the volume change process of the soil sample, turn on the second temperature and humidity sensor 12 to monitor the ambient temperature and humidity in the pressure chamber 10, turn on the water bath mechanism, start the air compressor 1, and then adjust the flowmeter and the third valve 26 on the passages of the humidifier 3 and the dryer 4 respectively to adjust the ratio between dry air and moist air, and adjust the air humidity from high to low (or from low to high). Then, record the data of all the above steps through the computer to obtain the moisture loss and moisture retention curves of the soil at different temperatures.

[0051] Compared with the traditional steam balance method, the above process can greatly shorten the time. The humidity can be converted into suction through the Kelvin formula, so the moisture loss and moisture absorption curve of the soil can be obtained by changing the humidity.

[0052] S4. Summarize the soil water retention-shrinkage curves of the above three stages.

[0053] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0054] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. Temperature-controlled soil water retention-shrinkage curve combined testing device, characterized by: The invention comprises a pressure chamber (10), wherein the pressure chamber (10) is sealed, and a water bath mechanism and a monitoring mechanism are connected to the pressure chamber (10), wherein the water bath mechanism is used to control the internal temperature of the pressure chamber (10), and the monitoring mechanism is used to observe the changes of the soil sample in the pressure chamber (10), and the pressure chamber (10) is connected to an air supply system, wherein the air supply system provides a test pressure for the soil sample in the pressure chamber (10), and the pressure chamber (10) is connected to a humidity control system, wherein the humidity control system provides a test humidity for the soil sample in the pressure chamber (10), and the pressure chamber (10) is connected to a flushing system, wherein the flushing system removes bubbles from the base of the pressure chamber (10) and provides test water for the soil sample in the pressure chamber (10), and the pressure chamber (10) is also connected to a liquid collection system, wherein the liquid collection system is used to collect and measure drainage of the soil sample in the pressure chamber (10); The humidity control system comprises an air compressor (1) and a humidity regulating unit. The outlet end of the air compressor (1) is connected to the humidity regulating unit. The humidity regulating unit is connected to the pressure chamber (10) through a third connecting pipe (30). The third connecting pipe (30) is connected to a first temperature and humidity sensor (5) and a digital pressure gauge (6). The humidity regulating unit is used to regulate the air humidity in the pressure chamber (10). The flushing system comprises a clay plate (15), a glass tube level gauge (21) and a micro vacuum pump (22), wherein the clay plate (15) is placed at the inner bottom of the pressure chamber (10), and the two sides of the pressure chamber (10) are respectively connected to the glass tube level gauges (21), and the bottom outlets of the two groups of the glass tube level gauges (21) are respectively connected to the bottom of the clay plate (15), and the inlet end of the micro vacuum pump (22) is connected to the pressure chamber (10) through a second connecting pipe (29), and a fourth valve (27) is provided on the second connecting pipe (29) to control the opening and closing of the micro vacuum pump (22); The liquid collecting system comprises a liquid collecting bottle (19) and a balance (23); the liquid collecting bottle (19) is connected to the bottom of the pressure chamber (10) via a second connecting pipe (29); the inlet end of the liquid collecting bottle (19) is connected to a second valve (25); and a balance (23) is placed below the liquid collecting bottle (19); The water bath mechanism comprises a temperature control chamber (9), the temperature control chamber (9) being arranged on the outside of the pressure chamber (10), and the temperature control chamber (9) being connected to a constant temperature water bath (8); The monitoring mechanism comprises a fixed truss (7), a camera (16) is fixedly connected to the top of the fixed truss (7), the camera (16) is located above the pressure chamber (10), laser rangefinders (17) are fixedly connected to both sides of the fixed truss (7), observation holes (18) are symmetrically opened on both sides of the temperature control chamber (9), two groups of laser rangefinders (17) are arranged corresponding to the pressure chamber (10) through the two groups of observation holes (18), and a light source (11) is connected to the top of the inner side of the pressure chamber (10); A porous plate (14) is connected to the inner wall of the pressure chamber (10), and a weighing sensor (13) is connected to the porous plate (14). The weighing sensor (13) is used to detect the mass change of the soil sample on the porous plate (14). A second temperature and humidity sensor (12) is also connected to the inner wall of the pressure chamber (10) for monitoring the ambient temperature and humidity in the pressure chamber (10).

2. The temperature-controlled soil water retention-shrinkage curve combined testing device according to claim 1, characterized in that: The air supply system comprises an air compressor (1), the air compressor (1) being connected to the pressure chamber (10) via a first connecting pipe (28), the first connecting pipe (28) being connected to a first valve (24) and a digital pressure gauge (6) for regulating the air pressure in the pressure chamber (10).

3. The temperature-controlled soil water retention-shrinkage curve combined testing device according to claim 1, characterized in that: The humidity regulating unit comprises a humidifier (3) and a dryer (4); a flow meter (2) and a third valve (26) are connected in sequence between the inlet end of the humidifier (3) and the air compressor (1), and between the inlet end of the dryer (4) and the air compressor (1); the outlet ends of the humidifier (3) and the dryer (4) are connected to the third connecting pipe (30).

4. A temperature-controlled soil water retention-shrinkage curve combined testing method, applied to the temperature-controlled soil water retention-shrinkage curve combined testing device according to claim 1, characterized in that: The steps include: S1, connecting the air supply system, the humidity control system, the pressure chamber (10), the water bath mechanism and the monitoring mechanism, adjusting the temperature and humidity in the pressure chamber (10) through the water bath mechanism and the humidity control system, observing the changes of the soil sample on the porous plate (14) through the monitoring mechanism, and obtaining the shrinkage curve of the soil according to the changes in the volume and mass of the soil sample; S2, low suction stage, connecting the air supply system, the pressure chamber (10), the water bath mechanism, the flushing system and the liquid collection system, starting the low-pressure dehumidification, observing the change in the volume of the soil sample on the clay plate (15) in the pressure chamber (10) through the monitoring mechanism, measuring the change in the soil mass through the liquid collection system, and obtaining the water retention curve of the soil within the low suction range based on the change in the soil sample; S3, high suction stage, connecting the air supply system, the humidity control system, the pressure chamber (10), the water bath mechanism and the monitoring system, starting the dehumidification under high suction, observing the mass and volume changes of the soil sample on the porous plate (14) in the pressure chamber (10) through the monitoring mechanism, and obtaining the water retention curve of the soil within the high suction range; S4. Summarize the soil water retention-shrinkage curves of the above three stages.

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