Soil dry-wet cycle device with hydrodynamic pressure regulation function and test method

Abstract

The application provides a soil dry-wet cycle device with hydrodynamic pressure regulation function and a test method, wherein the soil dry-wet cycle device comprises a test table, a support, a water pump, a water storage tank and an automatic dry-wet cycle mechanism, the automatic dry-wet cycle mechanism comprises a sealing top cover, a dry-wet cycle chamber, a dryer, a soil sample mounting unit and a controller, the soil sample mounting unit comprises a fixing structure, a microporous diaphragm bottom plate, a soil ring knife positioning sleeve frame and a microporous diaphragm top plate, the microporous diaphragm top plate and the microporous diaphragm bottom plate both have water-permeable and air-permeable structures, a first electromagnetic valve is installed on a water inlet pipe, a second electromagnetic valve is installed on a lower drain pipe, dryers are fixedly arranged at air inlets, and the controller is connected with the water pump, the dryers, the first electromagnetic valve and the second electromagnetic valve; and the application further provides a test method. The application can realize automatic quantitative research on the influence of dry-wet cycles on soil characteristics under different conditions in large quantities, and can also research the influence of different ions on soil characteristics in dry-wet cycles.

Description

Technical Field

[0001] This invention relates to a soil wet-dry circulation device in the field of geotechnical engineering, specifically to a soil wet-dry circulation device and test method with dynamic water pressure regulation function. Background Technology

[0002] In geotechnical engineering, soil undergoes changes in its physical structure and mechanical properties when subjected to long-term wet-dry cycles, leading to further geological hazards and engineering instability. Conducting wet-dry cycle tests on soil allows for a deeper understanding of its mechanical and deformation characteristics, guiding engineering practice and ensuring the safety and reliability of projects.

[0003] In conventional soil wetting-drying cycle tests, after preparing ring-shaped soil samples, different saturation times, drying temperatures, and the number of cycles are set to treat the soil through wetting-drying cycles. However, test devices such as stacked saturators and vacuum saturators can typically only saturate a limited number of soil samples, and no additional water pressure is applied during the saturation process, resulting in problems such as long saturation times and inconsistent saturation levels. Different types of water bodies in nature have significantly different ionic compositions, which also have varying effects on the geotechnical properties of soil during wetting-drying cycles. Existing test devices struggle to accurately measure changes in water ionic composition during soil wetting-drying cycle tests. Furthermore, in traditional tests, the saturation and drying processes are conducted in separate devices, potentially causing additional disturbance to the soil samples during transport. Therefore, achieving a saturation-wetting-drying cycle process for batches of soil samples under dynamic water pressure remains a theoretical and technical challenge that requires further in-depth research in the field of geotechnical engineering. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of prior art by providing a testing apparatus and method for soil wet-dry cycle testing under dynamic water pressure. This apparatus can accurately perform the following testing process: after the soil samples are installed, the apparatus can be automatically set to conduct multi-cycle wet-dry cycle tests on batch soil samples according to the testing requirements, maintaining a constant dynamic water pressure for soil sample saturation. It is equipped with upper and lower water taps for water sample collection and subsequent ionic composition determination. The process is automated, simplifying the testing procedure and controlling the influence of human factors on the test results.

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

[0006] A soil wet-dry circulation device with dynamic water pressure regulation function includes a test bench, a support fixed on the test bench, a water pump, a water storage tank, and an automatic wet-dry circulation mechanism. The automatic wet-dry circulation mechanism includes a sealed top cover, a wet-dry circulation chamber that seals with the sealed top cover, a dryer, a soil sample installation unit located in the wet-dry circulation chamber, and a controller. The wet-dry circulation chamber is fixed to the test bench by the support. The soil sample installation unit divides the wet-dry circulation chamber into upper and lower parts. The soil sample installation unit includes a microporous diaphragm bottom plate arranged from bottom to top by a fixing structure, a soil ring positioning sleeve frame for placing multiple soil ring cutters, and a microporous diaphragm top plate. The microporous diaphragm top plate and the microporous diaphragm bottom plate are all sealed to the inner wall of the wet-dry circulation chamber. The plate and the corresponding position of the soil ring cutter both have water-permeable and air-permeable structures. The bottom of the wet-dry circulation chamber is provided with a water inlet channel, which is connected to a water pump through a water inlet pipe. A first solenoid valve is installed on the end of the water inlet pipe near the wet-dry circulation chamber. Both the sealed top cover and the bottom of the wet-dry circulation chamber have drainage channels. The drainage channel on the sealed top cover is connected to a water storage tank through an upper drainage pipe. The drainage channel at the bottom of the wet-dry circulation chamber is connected to a water storage tank through a lower drainage pipe. A second solenoid valve is installed on the end of the lower drainage pipe near the wet-dry circulation chamber. The water pump and the water storage tank are connected by a pipe. The top of the sealed top cover and the bottom of the wet-dry circulation chamber both have air inlets, and a dryer is fixed at each air inlet. The controller is connected to the water pump, the dryer, the first solenoid valve, and the second solenoid valve, respectively.

[0007] Preferably, the fixing structure includes multiple threaded vertical support rods fixed to the upper part of the bottom of the wet-dry circulation chamber and two self-tightening nuts screwed onto the corresponding vertical support rods. The microporous diaphragm bottom plate, the soil ring positioning sleeve frame, and the microporous diaphragm top plate, arranged from bottom to top, are all inserted into each vertical support rod. The two self-tightening nuts are an upper positioning nut and a lower positioning nut. The upper positioning nut is located above the microporous diaphragm top plate, and the lower positioning nut is located below the microporous diaphragm bottom plate.

[0008] Preferably, a sealing rubber ring is provided between the sealing top cover and the dry-wet circulation chamber, and a fixing bolt passes through the sealing top cover and the sealing rubber ring from top to bottom and is screwed onto the dry-wet circulation chamber. The sealing top cover and the dry-wet circulation chamber are sealed together by the fixing bolt and the sealing rubber ring.

[0009] Preferably, two water taps are provided on the side of the wet-dry circulation chamber, with the two water taps positioned above and below the soil sample installation unit, respectively.

[0010] Preferably, a temperature sensor is also provided in the wet-dry circulation chamber. The temperature sensor is fixed on the inner side of the bottom plate of the wet-dry circulation chamber and connected to the controller.

[0011] Preferably, both the microporous membrane top plate and the microporous membrane bottom plate are made of impermeable material, and the water-permeable and air-permeable structure is a high-temperature resistant multilayer microporous membrane fixed in the through holes of the corresponding microporous membrane top plate and microporous membrane bottom plate. The high-temperature resistant multilayer microporous membrane is directly opposite the soil ring cutter, and the diameter of the high-temperature resistant multilayer microporous membrane is the same as the inner diameter of the soil ring cutter.

[0012] The test method using the aforementioned soil wet-dry cycle device includes the following steps:

[0013] Step 1: Using a pre-experiment approach, adjust the power of the dryer, the pressure of the water pump, and the opening of the first solenoid valve to test whether the water flow entering the automatic dry-wet circulation device and the drying conditions meet the requirements, and make corresponding adjustments; based on the results of the pre-experiment, set the dynamic water pressure, water flow rate, water flow time, drying temperature, drying time, and number of dry-wet cycles in each dry-wet cycle process through the controller.

[0014] Open the sealing top cover, adjust the position of the lower positioning nut, and place the microporous diaphragm base plate and soil ring cutter positioning sleeve frame in sequence. Then, place multiple soil ring cutters with soil samples in the soil ring cutter positioning sleeve frame. Next, place the microporous diaphragm top plate and fix it with the upper positioning nut. The thickness of the soil ring cutter positioning sleeve frame should be less than or equal to the height of the soil ring cutter to ensure that the microporous diaphragm top plate and the soil ring cutter are in close contact, and water will only flow into and out of the soil sample from the high-temperature resistant multilayer microporous diaphragm.

[0015] Step 2: The fixing bolts pass through the sealing top cover and the sealing rubber ring from top to bottom, and are screwed onto the dry and wet circulation chamber to seal and press the sealing top cover and the dry and wet circulation chamber tightly; thereby ensuring good airtightness of the internal space formed by the dry and wet circulation chamber and the sealing top cover.

[0016] Step 3: During the soil sample saturation process, the first solenoid valve is opened as needed, and the second solenoid valve is closed. Circulating water passes through the soil sample from bottom to top and then is discharged from the corresponding upper drain pipe. After the soil sample is saturated, the controller closes the first solenoid valve, closes the upper drain pipe through the third solenoid valve (not shown in the figure), and opens the second solenoid valve to drain the water.

[0017] Step 4: After drainage is completed, the soil sample is dried. During the drying process, the controller turns on the upper and lower dryers to dry the soil sample and controls the dryers according to the temperature sensor to keep the drying temperature constant at the temperature required by the test plan. The simultaneous operation of the upper and lower dryers can speed up the heating and drying process of the soil sample.

[0018] Step 5: Repeat steps 3 and 4 until the set number of wet-dry cycles is reached. The wet-dry cycle experiment is then complete.

[0019] Preferably, in step 3, water is collected from the top and bottom sides of the soil sample installation unit using two water taps for testing.

[0020] Preferably, in step 1, water samples containing different ionic components can be added to the water storage tank.

[0021] Compared with existing experimental devices, the beneficial effects of the present invention are as follows:

[0022] (1) In the process of soil wet-dry cycle test, the present invention can be set by the controller, such as quantitatively simulating different water pressure, flow rate and different drying time and temperature, and performing multiple wet-dry cycles;

[0023] (2) The soil sample installation unit of this invention can fix a large number of ring cutter soil samples at one time through its ingenious and simple structure. It divides the wet-dry cycle chamber into upper and lower parts, which provides conditions for setting dynamic water pressure. It adopts a high-temperature resistant multilayer microporous membrane, which can fix the soil sample during the wetting process, so that the soil sample particles are not washed away by the water flow, and does not affect the exhaust of air in the soil sample and the normal passage of water flow. It also allows water ions to pass through the microporous membrane and enter the soil sample normally, so as to study the effect of wet-dry cycle on the soil sample under dynamic water pressure, and the effect of different ions in the water on the soil sample. During the drying process, high-temperature drying can be carried out directly, avoiding the operation of removing the soil sample from the soil ring cutter and then drying it. It realizes repeated wet-dry cycle, avoids the tediousness of manual operation, speeds up the experimental process, effectively controls the error caused by manual operation, and realizes the fully automated control of the soil sample soaking-drying process. It can realize automated large-scale quantitative study of the effect of wet-dry cycle on soil properties under different conditions, and at the same time, it can study the effect of different ions on soil properties in wet-dry cycle.

[0024] (3) The test device provided by the present invention has a simple mechanical structure, is easy to adjust and convenient to operate, and can realize the simultaneous dry and wet cycle test of a large number of soils, which reduces the manual repetition of the test and improves the efficiency of the test.

[0025] (4) The fixed structure can adjust the vertical position of the soil sample installation unit according to the test requirements, which is very convenient.

[0026] (5) Two water taps are installed on the side of the wet and dry circulation chamber. The height of the two water taps is located above and below the soil sample installation unit, respectively, to collect water from the upper and lower sides of the soil sample installation unit and to determine the ion absorption of the soil sample. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the main structure of the soil wet-dry cycle device of the present invention;

[0028] Figure 2This is a schematic diagram of the main structure of the dry and wet circulation chamber provided by the present invention;

[0029] Figure 3 A top view of the dry and wet circulation chamber provided by the present invention;

[0030] Figure 4 This is a schematic diagram of a single test section in the dry-wet cycle chamber provided by the present invention.

[0031] In the diagram: 1-Dryer, 2-Sealed top cover, 3-Water tap, 4-Dry-wet circulation chamber, 5-Vertical support rod, 6-Self-tightening nut, 7-Microporous diaphragm top plate, 8-Soil ring cutter, 9-Soil ring cutter positioning sleeve frame, 10-Microporous diaphragm bottom plate, 11-Support, 12-Test bench, 13-Air inlet, 14-Drainage channel, 15-Drainage pipe, 15'-Lower drainage pipe, 16-Temperature sensor, 17-Water inlet channel, 18-Solenoid valve, 18'-Second solenoid valve, 19-Controller, 20-Water inlet pipe, 21-Water pump, 22-Water storage tank, 23-Fixing bolt, 24-Sealing rubber ring, 25-High temperature resistant multilayer microporous membrane, 26-Soil sample, 27-Water delivery pipe. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the following embodiments.

[0033] Example 1

[0034] A soil wet-dry circulation device with dynamic water pressure regulation function, such as Figure 1-4 As shown, the system includes a test bench 12, a support 11 fixed on the test bench, a water pump 21, a water storage tank 22, and an automatic wet-dry circulation mechanism. The automatic wet-dry circulation mechanism includes a sealed top cover 2, a wet-dry circulation chamber 4 that is sealed to the sealed top cover, a dryer 1, a soil sample installation unit located in the wet-dry circulation chamber, and a controller. A sealing rubber ring 24 is provided between the sealed top cover and the wet-dry circulation chamber. Fixing bolts 23 pass through the sealed top cover and the sealing rubber ring from top to bottom and are screwed onto the wet-dry circulation chamber. The sealed top cover and the wet-dry circulation chamber are sealed together by the fixing bolts and the sealing rubber ring. The wet-dry circulation chamber is fixed to the test bench 12 by the support 11. The soil sample installation unit divides the wet-dry circulation chamber into upper and lower parts.

[0035] The soil sample installation unit includes a microporous diaphragm base plate 10, a soil ring positioning sleeve frame 9 for placing multiple soil ring cutters 8, and a microporous diaphragm top plate 7, which are fixed from bottom to top by a fixed structure. The top and bottom microporous diaphragm plates are sealed to the inner wall of the wet-dry circulation chamber. The top and bottom microporous diaphragm plates have water-permeable and air-permeable structures at the positions corresponding to the soil ring cutters 8. In this embodiment, the top and bottom microporous diaphragm plates are made of impermeable materials, such as steel plates or plastic plates. The water-permeable and air-permeable structures are high-temperature resistant multilayer microporous diaphragms 25 fixed in the through holes of the corresponding microporous diaphragm top and bottom plates. The high-temperature resistant multilayer microporous diaphragms are directly opposite the soil ring cutters, and the diameter of the high-temperature resistant multilayer microporous diaphragms is the same as the inner diameter of the soil ring cutters. The fixed structure includes multiple threaded vertical support rods 5 fixed to the upper part of the bottom of the wet and dry circulation chamber, and two self-tightening nuts 6 screwed onto the corresponding vertical support rods. The microporous diaphragm bottom plate, soil ring positioning sleeve frame and microporous diaphragm top plate arranged from bottom to top are all inserted on each vertical support rod. The two self-tightening nuts are an upper positioning nut and a lower positioning nut. The upper positioning nut is located above the microporous diaphragm top plate and the lower positioning nut is located below the microporous diaphragm bottom plate.

[0036] A water inlet channel 17 is provided at the bottom of the wet and dry circulation chamber. The water inlet channel is connected to the water pump 21 through the water inlet pipe 20. A first solenoid valve 18 is installed on the end of the water inlet pipe near the wet and dry circulation chamber. Both the sealed top cover and the bottom of the wet and dry circulation chamber have drainage channels 14. The drainage channel on the sealed top cover is connected to the water storage tank 22 through the upper drainage pipe 15. The drainage channel 14 at the bottom of the wet and dry circulation chamber is connected to the water storage tank through the lower drainage pipe 15'. A second solenoid valve 18' is installed on the end of the lower drainage pipe near the wet and dry circulation chamber. The water pump and the water storage tank are connected through a pipe 27. Both the top of the sealed top cover and the bottom of the wet and dry circulation chamber have air inlets 13. A dryer 1 is fixed at each air inlet. The controller 19 is connected to the water pump 21, the dryer 1, the first solenoid valve 18, and the second solenoid valve 18', respectively.

[0037] In this embodiment, two water taps 3 are installed on the side of the wet-dry circulation chamber, with the two water taps positioned above and below the soil sample installation unit, respectively. These taps are used to collect water from both sides of the soil sample installation unit, and the ion absorption of the soil sample is measured.

[0038] A temperature sensor 16 is also installed in the wet-dry circulation chamber. The temperature sensor is fixed on the inner side of the bottom plate of the wet-dry circulation chamber and connected to the controller. During operation, the temperature sensor 16 senses the temperature of the sealed space formed by the wet-dry circulation chamber 4 and the sealed top cover 2 and transmits the data to the controller 19. The controller 19 controls the heating temperature of the dryer 1 according to the temperature data, so as to achieve the function of keeping the temperature constant during the drying process of the soil sample 26.

[0039] Example 2

[0040] The test method using the above-mentioned soil wet-dry cycle device includes the following steps:

[0041] Step 1: Using a pre-experiment method, adjust the power of dryer 1, the pressure of water pump 21, and the opening of the first solenoid valve 18 to test whether the water flow entering the automatic dry and wet circulation device and the drying conditions meet the requirements, and make corresponding adjustments; based on the results of the pre-experiment, set the dynamic water pressure, water flow rate, water flow time, drying temperature, drying time, and number of dry and wet cycles in each dry and wet cycle process through the controller.

[0042] Open the sealing top cover, adjust the position of the lower positioning nut, and place the microporous diaphragm bottom plate and the soil ring cutter positioning sleeve frame in sequence. Then, place multiple soil ring cutters with soil samples in the soil ring cutter positioning sleeve frame. Next, place the microporous diaphragm top plate and fix it with the upper positioning nut. The thickness of the soil ring cutter positioning sleeve frame is less than or equal to the height of the soil ring cutter to ensure that the microporous diaphragm top plate 7 and the soil ring cutter 8 are in close contact, and the water flow will only flow into and out of the soil sample 26 from the high-temperature resistant multilayer microporous diaphragm 25.

[0043] Step 2: The fixing bolts pass through the sealing top cover and the sealing rubber ring from top to bottom and are screwed onto the dry and wet circulation chamber to seal and press the sealing top cover and the dry and wet circulation chamber tightly; thereby ensuring good airtightness of the internal space formed by the dry and wet circulation chamber 4 and the sealing top cover 2.

[0044] Step 3: During the soil sample saturation process, the first solenoid valve is opened as needed, and the second solenoid valve is closed. Circulating water passes through the soil sample from bottom to top and is then discharged from the corresponding upper drain pipe 15. After the soil sample is saturated, the controller closes the first solenoid valve, closes the upper drain pipe 15 through the third solenoid valve (not shown in the figure), and opens the second solenoid valve to drain the water.

[0045] Step 4: After drainage is completed, the soil sample is dried. During the drying process, the controller turns on the upper and lower dryers to dry the soil sample and controls the dryer 1 according to the temperature sensor 16 to keep the drying temperature constant at the temperature required by the test plan. The simultaneous operation of the upper and lower dryers can speed up the heating and drying process of the soil sample 26.

[0046] Step 5: Repeat steps 3 and 4 until the set number of wet-dry cycles is reached. The wet-dry cycle experiment is then complete.

[0047] In step 3, water is collected from the top and bottom sides of the soil sample installation unit using two water taps for testing.

[0048] In step 1, water samples containing different ionic components can be added to the water storage tank.

Claims

1. A soil wet-dry circulation device with dynamic water pressure regulation function, comprising a test bench, a support fixed on the test bench, a water pump, a water storage tank, and an automatic wet-dry circulation mechanism, characterized in that: The automatic wet-dry circulation mechanism includes a sealed top cover, a wet-dry circulation chamber that seals with the top cover, a dryer, a soil sample installation unit located in the wet-dry circulation chamber, and a controller. The wet-dry circulation chamber is fixed to the test bench by supports. The soil sample installation unit divides the wet-dry circulation chamber into upper and lower parts. The soil sample installation unit includes a microporous diaphragm bottom plate, a soil ring positioning sleeve for placing multiple soil ring cutters, and a microporous diaphragm top plate, all arranged from bottom to top by a fixing structure. The microporous diaphragm top plate and the microporous diaphragm bottom plate are sealed to the inner wall of the wet-dry circulation chamber on all four sides. The positions of the microporous diaphragm top plate and the microporous diaphragm bottom plate corresponding to the soil ring cutters have water-permeable and air-permeable structures. A water inlet channel is provided at the bottom, which is connected to a water pump via an inlet pipe. A first solenoid valve is installed on the end of the inlet pipe near the dry-wet circulation chamber. Both the sealed top cover and the bottom of the dry-wet circulation chamber have drainage channels. The drainage channel on the sealed top cover is connected to a water storage tank via an upper drainage pipe, and the drainage channel at the bottom of the dry-wet circulation chamber is connected to the water storage tank via a lower drainage pipe. A second solenoid valve is installed on the end of the lower drainage pipe near the dry-wet circulation chamber. The water pump and the water storage tank are connected via a pipe. Both the top of the sealed top cover and the bottom of the dry-wet circulation chamber have air inlets, and a dryer is fixed at each air inlet. The controller is connected to the water pump, the dryer, the first solenoid valve, and the second solenoid valve, respectively.

2. The soil wet-dry circulation device with dynamic water pressure regulation function according to claim 1, characterized in that: The fixing structure includes multiple threaded vertical support rods fixed to the upper part of the bottom of the wet-dry circulation chamber and two self-tightening nuts screwed onto the corresponding vertical support rods. The microporous diaphragm bottom plate, soil ring positioning sleeve frame and microporous diaphragm top plate arranged from bottom to top are all inserted on each vertical support rod. The two self-tightening nuts are an upper positioning nut and a lower positioning nut. The upper positioning nut is located above the microporous diaphragm top plate and the lower positioning nut is located below the microporous diaphragm bottom plate.

3. The soil wet-dry circulation device with dynamic water pressure regulation function according to claim 2, characterized in that: A sealing rubber ring is provided between the sealing top cover and the dry-wet circulation chamber. The fixing bolt passes through the sealing top cover and the sealing rubber ring from top to bottom and is screwed onto the dry-wet circulation chamber. The sealing top cover and the dry-wet circulation chamber are sealed together by the fixing bolt and the sealing rubber ring.

4. The soil wet-dry circulation device with dynamic water pressure regulation function according to claim 3, characterized in that: Two water taps are installed on the side of the wet-dry circulation chamber, with the two water taps positioned above and below the soil sample installation unit, respectively.

5. The soil wet-dry circulation device with dynamic water pressure regulation function according to claim 4, characterized in that: A temperature sensor is also installed in the wet-dry circulation chamber. The temperature sensor is fixed to the inside of the bottom plate of the wet-dry circulation chamber and connected to the controller.

6. The soil wet-dry circulation device with dynamic water pressure regulation function according to claim 5, characterized in that: Both the top and bottom plates of the microporous membrane are made of impermeable materials. The permeable and breathable structure is a high-temperature resistant multilayer microporous membrane fixed in the through holes of the corresponding top and bottom plates. The high-temperature resistant multilayer microporous membrane is directly opposite the soil ring cutter, and the diameter of the high-temperature resistant multilayer microporous membrane is the same as the inner diameter of the soil ring cutter.

7. A soil wet-dry cycle test method with dynamic water pressure regulation function, using the soil wet-dry cycle device according to claim 6, characterized in that... Includes the following steps: Step 1: Using a pre-experiment approach, adjust the power of the dryer, the pressure of the water pump, and the opening of the first solenoid valve to test whether the water flow entering the automatic dry-wet circulation device and the drying conditions meet the requirements, and make corresponding adjustments; based on the results of the pre-experiment, set the dynamic water pressure, water flow rate, water flow time, drying temperature, drying time, and number of dry-wet cycles in each dry-wet cycle process through the controller. Open the sealing top cover, adjust the position of the lower positioning nut, and place the microporous diaphragm base plate and soil ring cutter positioning sleeve frame in sequence. Then, place multiple soil ring cutters with soil samples in the soil ring cutter positioning sleeve frame. Next, place the microporous diaphragm top plate and fix it with the upper positioning nut. The thickness of the soil ring cutter positioning sleeve frame should be less than or equal to the height of the soil ring cutter to ensure that the microporous diaphragm top plate and the soil ring cutter are in close contact, and water will only flow into and out of the soil sample from the high-temperature resistant multilayer microporous diaphragm. Step 2: The fixing bolts pass through the sealing top cover and the sealing rubber ring from top to bottom, and are screwed onto the dry and wet circulation chamber to seal and press the sealing top cover and the dry and wet circulation chamber tightly; thereby ensuring good airtightness of the internal space formed by the dry and wet circulation chamber and the sealing top cover. Step 3: During the soil sample saturation process, the first solenoid valve is opened as needed, and the second solenoid valve is closed. Circulating water passes through the soil sample from bottom to top and is then discharged from the corresponding upper drain pipe. Once the soil sample is saturated, the controller closes the first solenoid valve, closes the upper drain pipe through the third solenoid valve, and opens the second solenoid valve to drain the water. Step 4: After drainage is completed, drying is carried out. During the drying process, the controller turns on the upper and lower dryers to dry the soil sample and controls the dryers according to the temperature sensor to keep the drying temperature constant at the temperature required by the test plan. The upper and lower dryers work at the same time. Step 5: Repeat steps 3 and 4 until the set number of wet-dry cycles is reached. The wet-dry cycle experiment is then complete.

8. The soil wet-dry cycle test method with dynamic water pressure regulation function according to claim 7, characterized in that: In step 3, water is collected from the top and bottom sides of the soil sample installation unit using two water taps for testing.

9. The soil wet-dry cycle test method with dynamic water pressure regulation function according to claim 7, characterized in that: In step 1, water samples containing different ionic components are added to the water storage tank.

Images