Dry-wet cycle soil sample test device and method based on electroosmosis

Abstract

The invention discloses a dry-wet cycle soil sample test device and method based on the electro-osmosis method, belonging to the technical field of road engineering. The technical problem to be solved by the invention is the softening of the end of the specimen and the uneven moisture content of the inner and outer parts of the specimen during the dry-wet cycle process. The technical scheme adopted is: its structure includes an electronic balance base, a water collecting trough is arranged on the electronic balance base, a plurality of water collecting holes are arranged on the upper side of the water collecting trough, and a sample mold is arranged on the upper side of the water collecting trough, a positive plate is arranged on the upper inner wall of the sample mold, a negative plate is arranged on the lower inner wall of the sample mold, a wire is arranged between the positive plate and the negative plate, and a DC power supply is arranged on the wire; a water inlet unit is arranged on the positive plate, and a drainage unit is connected to the water collecting trough.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, in particular to a dry-wet cycle soil sample testing device and method based on an electroosmosis method. Background Art

[0002] In the study of the change of soil moisture content, the method of directly preparing samples with different moisture contents is generally adopted. However, this sample preparation method does not conform to the actual process of the roadbed being filled at the optimal moisture content and then undergoing humidity cycle changes. In addition, different sample moisture contents will lead to different soil structures and cannot accurately reflect the influence of moisture content on the mechanical properties of roadbed soil. At present, some improvement methods have been proposed for the humidification and dehumidification process of soil specimens in the dry-wet cycle, but there are still some problems. For example, by using simple immersion or water spraying to humidify, the change process of sample moisture content and the test target moisture content are not easy to quantitatively control, uneven humidification causes softening at both ends of the specimen, and uneven dehumidification causes large cracks in the specimen. These problems are crucial to truly reflect the impact of repeated wetting on roadbed performance.

[0003] Therefore, how to avoid the softening of the specimen ends and the uneven moisture content inside and outside the specimen during the dry-wet cycle is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The technical task of the present invention is to provide a dry-wet cycle soil sample testing device and method based on the electroosmosis method to solve the problems of softening of the specimen ends and uneven moisture content inside and outside the specimen during the dry-wet cycle process.

[0005] The technical task of the present invention is achieved in the following way: a dry-wet cycle soil sample testing device based on the electro-osmosis method, the device comprising an electronic balance base, a water collecting trough is arranged on the electronic balance base, a plurality of water collecting holes are arranged on the upper side of the water collecting trough and a sample mold is arranged on the upper side of the water collecting trough, a positive electrode plate is arranged on the upper inner wall of the sample mold, a negative electrode plate is arranged on the lower inner wall of the sample mold, a wire is arranged between the positive electrode plate and the negative electrode plate, and a DC power supply is arranged on the wire; a water inlet unit is arranged on the positive electrode plate, and the water collecting trough is connected to a drainage unit.

[0006] Preferably, the water inlet unit includes a water reservoir, a water pump 1 and a water inlet pipe 2. The water reservoir is connected to the inlet end of the water pump 1 through the water pumping pipe. The outlet end of the water pump 1 is provided with a water inlet pipe 1. The water inlet pipe 1 is divided into two paths: one path is connected to one end of the water inlet pipe 2, and the other end of the water inlet pipe 2 is connected to the positive plate; the other path is connected to a drainage main.

[0007] More preferably, the water inlet pipe one is provided with a water inlet valve one, and the water inlet pipe two is provided with a water inlet valve two.

[0008] Preferably, the drainage unit comprises a drainage trough, a water pump 2, a drainage branch pipe 1 and a drainage branch pipe 2, one end of the drainage branch pipe 2 is connected to the sump, the other end of the drainage branch pipe 2 is connected to the inlet end of the water pump 2, and the outlet end of the water pump 2 is divided into two paths: one path is connected to the drainage main pipe, and the other path is connected to one end of the drainage branch pipe 1, and the other end of the drainage branch pipe 1 is connected to the drainage trough.

[0009] More preferably, the main drainage pipe is provided with a first drainage valve, and the first drainage branch pipe is provided with a second drainage valve.

[0010] Preferably, a transparent sealing cover is arranged outside the water collection tank, a movable cover is arranged at the upper end of the transparent sealing cover, the lower end of the transparent sealing cover is installed on the electronic balance base, and the sample mold, positive plate and negative plate are all arranged in the transparent sealing cover.

[0011] Preferably, the positive plate and the negative plate are both provided with a plurality of water-permeable holes, which are distributed in a circular pattern at the center of the positive plate or the negative plate, and are distributed in a linear scattered pattern from the center to the edge.

[0012] A dry-wet cycle soil sample test method based on electroosmosis, the method is as follows:

[0013] S1. Prepare soil samples according to requirements, calculate the initial mass m0, initial moisture content ω0 and porosity n of the soil samples, insert the test soil samples into the sample mold, place one end of the test soil samples on the negative electrode plate, and place the positive electrode plate on the other end of the test soil samples;

[0014] S2. Calculate the water mass Δm required for the humidification process ω , the formula is as follows:

[0015]

[0016] Among them, ω1 represents the moisture content after humidification;

[0017] S3. Determine the test DC voltage U0, the formula is as follows:

[0018] U0=1.25h;

[0019] Where, h represents the height of the soil sample;

[0020] S4. Determine the electrical permeability coefficient k e , the formula is as follows:

[0021]

[0022] Where D is the dielectric constant of water, in units of E / m; ζ is the electromotive force, in units of V; υ is the dynamic viscosity of water, in units of Pa·s;

[0023] S5. Determine the electroosmotic drainage rate υ e , the formula is as follows:

[0024]

[0025] Where S represents the cross-sectional area of ​​the specimen;

[0026] S6. Estimate the time t required for humidification, the formula is as follows:

[0027]

[0028] Among them, ρ ω Indicates the density of water;

[0029] S7, moistening the test soil sample according to the acquisition time;

[0030] S8. Dehumidify the test soil sample according to the acquisition time.

[0031] As a preferred embodiment, the humidification treatment process of the test soil sample is as follows:

[0032] (1) Open the water inlet unit, turn on the water pump 1, unscrew the water inlet valve 1 and the water inlet valve 2, and add the water required for humidification to the top of the test soil sample; after the water is added, turn off the water pump 1 and the water inlet valve 1, and open the drain valve 1 and the water pump 2;

[0033] (2) Turn on the DC power supply, set the voltage to U0, start humidification, and make the moisture at the top of the test soil sample migrate to the bottom. At the same time, the moisture at the bottom is collected into the water collection tank through the negative plate and the water collection hole, and circulated to the top of the test soil sample through the drainage system unit. After time t, turn off the DC power supply;

[0034] (3) Close the movable cover on the transparent sealing cover and let the test soil sample stand for more than 24 hours to complete a humidification treatment process.

[0035] Preferably, the dehumidification process of the test soil sample is as follows:

[0036] (1) Close water inlet valve 1, water inlet valve 2 and drain valve 1, and open drain valve 2;

[0037] (2) Turn on the DC power supply and the second pump to start dehumidification, so that the moisture on the top of the test soil sample migrates to the bottom. At the same time, the moisture at the bottom is collected into the water collection tank through the negative plate and the water collection hole, and discharged into the external drainage tank through the drainage branch pipe 2 and the drainage branch pipe 1. At the same time, pay attention to the mass loss of the electronic balance. After time t, turn off the DC power supply;

[0038] (3) Close the movable cover on the transparent sealing cover and let the test soil sample stand for more than 24 hours to complete the dehumidification process.

[0039] The dry-wet cycle soil sample test device and method based on the electroosmotic method of the present invention have the following advantages:

[0040] (1) The present invention is simple and easy to operate, avoiding the need to move the test piece during the test, which may damage the test piece;

[0041] (ii) The present invention ensures that each part of the specimen reaches the target moisture content state during the dry-wet cycle;

[0042] (III) The present invention avoids the occurrence of situations such as softening of both ends of the specimen due to uneven humidification and large cracks in the specimen due to uneven dehumidification.

[0043] Therefore, the invention has the characteristics of reasonable design, simple structure, easy processing, small size, convenient use, multi-purpose, etc., and thus has good promotion and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention is further described below in conjunction with the accompanying drawings.

[0045] Attached Figure 1 It is a schematic diagram of the structure of the dry-wet cycle soil sample test device based on the electroosmosis method;

[0046] Attached Figure 2 For attachment Figure 1 A schematic diagram of the structure of the positive plate or the negative plate;

[0047] Attached Figure 3 This is a schematic diagram of the structure of the water collection tank.

[0048] In the figure: 1. electronic balance base, 2. water collecting tank, 3. water collecting hole, 4. sample mold, 5. positive plate, 6. negative plate, 7. wire, 8. DC power supply, 9. water storage tank, 10. water pump 1, 11. water inlet pipe 1, 12. water inlet pipe 2, 13. water pump, 14. water inlet valve 1, 15. water inlet valve 2, 16. drainage tank, 17. water pump 2, 18. drainage branch pipe 1, 19. drainage branch pipe 2, 20. drainage main pipe, 21. drainage valve 1, 22. drainage valve 2, 23. transparent sealing cover, 24. movable cover plate, 25. water permeable hole. DETAILED DESCRIPTION

[0049] The dry-wet cycle soil sample testing device and method based on the electroosmosis method of the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] Embodiment 1:

[0053] As attached Figure 1 As shown, this embodiment provides a dry-wet cycle soil sample test device based on the electro-osmosis method, and its structure includes an electronic balance base 1, a water collecting tank 2 is installed on the electronic balance base 1, a plurality of water collecting holes 3 are opened on the upper side of the water collecting tank 2, and a sample mold 4 is installed on the upper side of the water collecting tank 2, a positive electrode plate 5 is installed on the upper inner wall of the sample mold 4, a negative electrode plate 6 is installed on the lower inner wall of the sample mold 4, a wire 7 is installed between the positive electrode plate 5 and the negative electrode plate 6, and a DC power supply 8 is installed on the wire 7; a water inlet unit is installed on the positive electrode plate 5, and the water collecting tank is connected to a drainage unit.

[0054] The water inlet unit in this embodiment includes a water reservoir 9, a water pump 10 and a water inlet pipe 12. The water reservoir 9 is connected to the inlet end of the water pump 10 through a water pump 13. The outlet end of the water pump 10 is connected to a water inlet pipe 11. The water inlet pipe 11 is divided into two paths: one path is connected to one end of the water inlet pipe 12, and the other end of the water inlet pipe 12 is connected to the positive plate 5; the other path is connected to the drainage main pipe 20.

[0055] In this embodiment, a water inlet valve 14 is installed on the water inlet pipe 11, and a water inlet valve 2 15 is installed on the water inlet pipe 2 12.

[0056] The drainage unit in this embodiment includes a drainage trough 16, a water pump 17, a drainage branch pipe 18 and a drainage branch pipe 19. One end of the drainage branch pipe 19 is connected to the water collecting trough 2, and the other end of the drainage branch pipe 19 is connected to the inlet end of the water pump 17. The outlet end of the water pump 17 is divided into two paths: one path is connected to the drainage main pipe 20, and the other path is connected to one end of the drainage branch pipe 18. The other end of the drainage branch pipe 18 is connected to the drainage trough 16.

[0057] In this embodiment, a drain valve 21 is installed on the drain main pipe 20, and a drain valve 22 is installed on the drain branch pipe 18.

[0058] A transparent sealing cover 23 is installed on the outside of the water collection tank 2 in this embodiment. A movable cover 24 is provided on the upper end of the transparent sealing cover 23. The lower end of the transparent sealing cover 23 is installed on the electronic balance base 1. The sample mold 4, the positive plate 5 and the negative plate 6 are all installed in the transparent sealing cover 23.

[0059] In this embodiment, a plurality of water-permeable holes 25 are provided on the positive plate 4 and the negative plate 5 . The water-permeable holes 25 are distributed in a circular pattern at the center of the positive plate 4 or the negative plate 5 , and are distributed in a linear scattered pattern from the center to the edge.

[0060] In this embodiment, the voltage of the DC power supply 8 is selected according to the height of the sample, which is 1-1.5V / cm, preferably 1.25V / cm, and is connected to the positive plate 5 and the negative plate 6 through the wire 7. The material of the positive plate 5 is preferably a rubber graphite electrode, which is a circular structure with a honeycomb structure inside to facilitate the circulation of water. The thickness is 0.5-1.5cm, preferably 1cm, and the diameter is determined according to the diameter of the specimen, generally not exceeding 15cm. The material of the negative plate 6 is preferably copper, which is a circular structure with a honeycomb structure permeable hole inside to facilitate the circulation of water. The thickness is 0.5-1.5cm, preferably 1cm, and the diameter is determined according to the diameter of the specimen, generally not exceeding 15cm.

[0061] The sample mold 4 in this embodiment is made of non-conductive material, preferably plastic, which can wrap the sides of the sample to prevent moisture from flowing out from the sides. The thickness is 1-2 cm, preferably 1.5 cm, and the height is 2 cm higher than the sample height. The diameter is determined according to the diameter of the specimen.

[0062] The purpose of the water inlet unit and the drainage unit in this embodiment is to add water to the sample and drain water during the humidification and dehumidification process of the sample.

[0063] The function of the electronic balance base 1 in this embodiment is to monitor the quality of the test piece in real time. The upper part of the electronic balance base 1 is a water collecting tank 2. A plurality of water collecting holes 3 are provided on the upper side of the plastic water collecting tank 2 to collect the water discharged from the test soil sample.

[0064] The transparent sealing cover 23 in this embodiment is a rectangular parallelepiped, the lower part of which is connected to the electronic balance base 1, and the upper part of which is a movable cover 24. After the test piece is installed, the upper movable cover 24 of the transparent sealing cover 23 is closed to form a closed space inside. The transparent sealing cover 23 is used to observe the internal operation of the equipment and ensure that the internal humidity is in a stable state.

[0065] Embodiment 2:

[0066] This embodiment provides a dry-wet cycle soil sample test method based on the electroosmotic method, and the method is specifically as follows:

[0067] S1. Prepare soil samples according to requirements, calculate the initial mass m0, initial moisture content ω0 and porosity n of the soil samples, insert the test soil samples into the sample mold 4, place one end of the test soil samples on the negative electrode plate 6, and place the positive electrode plate 5 on the other end of the test soil samples;

[0068] S2. Calculate the water mass Δm required for the humidification process ω , the formula is as follows:

[0069]

[0070] Among them, ω1 represents the moisture content after humidification;

[0071] S3. Determine the test DC voltage U0, the formula is as follows:

[0072] U0=1.25h;

[0073] Where, h represents the height of the soil sample;

[0074] S4. Determine the electrical permeability coefficient k e , the formula is as follows:

[0075]

[0076] Where D is the dielectric constant of water, in units of E / m; ζ is the electromotive force, in units of V; υ is the dynamic viscosity of water, in units of Pa·s;

[0077] S5. Determine the electroosmotic drainage rate υ e , the formula is as follows:

[0078]

[0079] Where S represents the cross-sectional area of ​​the specimen;

[0080] S6. Estimate the time t required for humidification, the formula is as follows:

[0081]

[0082] Among them, ρω Indicates the density of water;

[0083] S7, moistening the test soil sample according to the acquisition time;

[0084] S8. Dehumidify the test soil sample according to the acquisition time.

[0085] The humidification treatment process of the test soil sample in step S7 of this embodiment is specifically as follows:

[0086] (1) Open the water inlet unit, turn on the water pump 10, unscrew the water inlet valve 14 and the water inlet valve 2 15, and add the water required for humidification to the top of the test soil sample; after the water is added, turn off the water pump 10 and the water inlet valve 14, and open the drain valve 21 and the water pump 2 17;

[0087] (2) Turn on the DC power supply 8, set the voltage to U0, start humidification, so that the moisture at the top of the test soil sample migrates to the bottom inside, and at the same time, the moisture at the bottom is collected into the water collection tank 2 through the negative plate 6 and the water collection hole 3, and circulates to the top of the test soil sample through the drainage system unit. After time t, turn off the DC power supply 8;

[0088] (3) Close the movable cover plate 24 on the transparent sealing cover 23 and let the test soil sample stand for more than 24 hours to complete a humidification treatment process.

[0089] The dehumidification process of the test soil sample in step S7 of this embodiment is specifically as follows:

[0090] (1) Close the water inlet valve 14, water inlet valve 2 15 and drain valve 1 21, and open drain valve 2 22;

[0091] (2) Turn on the DC power supply 8 and the second pump 17 to start dehumidification, so that the moisture on the top of the test soil sample migrates to the bottom. At the same time, the moisture at the bottom is collected into the water collection tank 2 through the negative plate 6 and the water collection hole 3, and discharged into the external drainage tank 16 through the drainage branch pipe 2 19 and the drainage branch pipe 1 18. At the same time, pay attention to the mass loss of the electronic balance. After time t, turn off the DC power supply 8;

[0092] (3) Close the movable cover plate 24 on the transparent sealing cover 23 and let the test soil sample stand for more than 24 hours to complete a dehumidification process.

[0093] Embodiment 3:

[0094] A cylindrical test piece with a diameter of 50 mm and a height of 100 mm was prepared. The mass of the soil sample was m0 = 400 g, the initial moisture content ω0 = 14.3%, and the porosity n = 0.9. The test piece was inserted into the sample mold 4, so that one end of the test soil sample was placed on the negative electrode plate 6, and the positive electrode plate 5 was placed on the other end of the test soil sample. The dry-wet cycle process of the test soil sample was: the humidification process was from a moisture content of 14.3% to a moisture content of 19.3%, and the dehumidification process was from a moisture content of 19.3% to a moisture content of 14.3%.

[0095] Determine the test DC voltage U0 to be 12.5V and calculate the electrical permeability coefficient k e 8.7×10 -5 cm 2 / sV, the estimated humidification time is about 19.2h. Open the water inlet unit, turn on the water pump 10, unscrew the water inlet valve 14 and the water inlet valve 2 15, and add the water required for humidification to the top of the test soil sample. After the water is added, turn off the water pump 10 and the water inlet valve 14, and open the drainage valve 21 and the water pump 2 17.

[0096] Turn on the DC power supply 8, set the voltage to 12.5V, start humidification, and make the moisture on the top of the test soil sample migrate to the bottom inside. At the same time, the moisture at the bottom is collected into the water collection tank 2 through the negative plate 6 and the water collection hole 3, and circulated to the top of the test soil sample through the drainage unit. After 19.2 hours, turn off the DC power supply 8. Then close the movable cover 24 on the transparent sealing cover 23, and let the test soil sample stand for more than 24 hours. The humidification process is completed.

[0097] Close the water inlet valve 14, water inlet valve 2 15 and drain valve 1 21, open drain valve 2 22, turn on the DC power supply 8 and pump 2 17, start dehumidification, and make the moisture on the top of the test soil sample migrate to the bottom internally. At the same time, the moisture at the bottom is collected into the water collection tank 2 through the negative plate 6 and the water collection hole 3, and discharged into the external drainage tank 16 through the drainage branch pipe 2 19 and the drainage branch pipe 1 18. At the same time, pay attention to the mass loss of the electronic balance. After 19.2 hours, turn off the DC power supply. Then close the upper movable cover 24 of the transparent sealing cover 23, and let the test soil sample stand for more than 24 hours. The dehumidification process is completed.

[0098] After humidification and dehumidification, the uniformity of moisture content inside the test soil sample was verified. The test soil sample was divided into 5 parts with a height of 20 mm, and the moisture content of each part was tested respectively. The results showed that the moisture content at different heights of the specimen was evenly distributed, and there was no softening phenomenon at the end.

[0099] The moisture content of the specimens at different heights is shown in Table 1:

[0100] Table 1 Moisture content of specimens at different heights

[0101] Height range Moisture content after humidification / % Moisture content after dehumidification / % 0-20mm 19.2 14.4 20-40mm 19.4 14.3 40-60mm 19.3 14.4 60-80mm 19.4 14.2 80-100mm 19.3 14.3

[0102] Comparative Example:

[0103] The wet-dry cycle specimen was prepared by the method in the embodiment, and a permeable stone was placed at the top and bottom of the specimen. The wet-dry cycle process of the specimen was: the moisture content was from 14.3% to 19.3% during the humidification process, and the moisture content was from 19.3% to 14.3% during the dehumidification process.

[0104] The required amount of water is evenly infiltrated into the sample through the permeable stone on the top surface, and the sample is placed in a closed humidifier for no less than 48 hours. After humidification, the sample is taken out of the humidifier, placed in an oven, and dried at a constant temperature of 40°C with blowing air for no less than 24 hours, until it is air-dried to the required quality.

[0105] After humidification and dehumidification, the uniformity of the moisture content inside the sample was verified. The sample was divided into 5 parts with a height of 20 mm, and the moisture content of each part was tested separately. The results showed that the moisture content at different heights of the specimen was unevenly distributed, and softening occurred at the end. During the humidification process, the moisture content in the middle part was significantly lower than that at the end, and during the dehumidification process, the moisture content in the middle part was significantly higher than that at the end. This indicates that during the dry-wet cycle, moisture gathered at the end and did not evenly penetrate the middle of the specimen, resulting in poor humidification and dehumidification effects.

[0106] The moisture content of the specimens at different heights is shown in Table 2:

[0107] Table 2 Moisture content of specimens at different heights

[0108] Height range Moisture content after humidification / % Moisture content after dehumidification / % 0-20mm 20.4 13.5 20-40mm 19.4 14.6 40-60mm 18.6 15.3 60-80mm 18.8 14.4 80-100mm 20.7 13.6

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dry-wet cycle soil sample test device based on electroosmosis method, characterized in that: The device comprises an electronic balance base, a water collecting tank is arranged on the electronic balance base, a plurality of water collecting holes are arranged on the upper side of the water collecting tank, and a sample mold is arranged on the upper side of the water collecting tank, a positive plate is arranged on the upper inner side wall of the sample mold, a negative plate is arranged on the lower inner side wall of the sample mold, a wire is arranged between the positive plate and the negative plate, and a DC power supply is arranged on the wire; a water inlet unit is arranged on the positive plate, and the water collecting tank is connected to a drainage unit; The water inlet unit includes a water reservoir, a water pump 1 and a water inlet pipe 2. The water reservoir is connected to the inlet end of the water pump 1 through the water pumping pipe. The outlet end of the water pump 1 is provided with a water inlet pipe 1. The water inlet pipe 1 is divided into two paths: one path is connected to one end of the water inlet pipe 2, and the other end of the water inlet pipe 2 is connected to the positive plate; the other path is connected to the drainage main pipe; a water inlet valve 1 is provided on the water inlet pipe 1, and a water inlet valve 2 is provided on the water inlet pipe 2; The drainage unit comprises a drainage trough, a water pump 2, a drainage branch pipe 1 and a drainage branch pipe 2, one end of the drainage branch pipe 2 is connected to the water collection trough, the other end of the drainage branch pipe 2 is connected to the inlet end of the water pump 2, and the outlet end of the water pump 2 is divided into two paths: one path is connected to the drainage main pipe, and the other path is connected to one end of the drainage branch pipe 1, and the other end of the drainage branch pipe 1 is connected to the drainage trough; a drainage valve 1 is arranged on the drainage main pipe, and a drainage valve 2 is arranged on the drainage branch pipe 1; A plurality of water-permeable holes are arranged on both the positive plate and the negative plate. The water-permeable holes are distributed in a circular pattern at the center of the positive plate or the negative plate, and are distributed in a linear scattered pattern from the center to the edge.

2. The dry-wet cycle soil sample test device based on the electroosmotic method according to claim 1 is characterized in that: A transparent sealing cover is arranged outside the water collecting tank, a movable cover is arranged on the upper end of the transparent sealing cover, the lower end of the transparent sealing cover is installed on the electronic balance base, and the sample mold, positive plate and negative plate are all arranged in the transparent sealing cover.

3. A test method using the dry-wet cycle soil sample test device based on electroosmosis method according to claim 1 or 2, characterized in that: The method is as follows: S1. Prepare soil samples according to requirements and calculate the initial mass of soil samples , initial moisture content and porosity , put the test soil sample into the sample mold, place one end of the test soil sample on the negative electrode plate, and place the positive electrode plate on the other end of the test soil sample; S2. Calculate the water mass required for the humidification process , the formula is as follows: ； in, Indicates the moisture content after humidification; S3. Determine the test DC voltage , the formula is as follows: ； Where, h represents the height of the soil sample; S4. Determine the electrical permeability coefficient , the formula is as follows: ； in, Represents the dielectric constant of water, in E / m; Represents electromotive force, unit is V; It represents the dynamic viscosity of water, in Pa·s; S5. Determine the electroosmotic drainage rate , the formula is as follows: ； in, Indicates the cross-sectional area of ​​the specimen; S6. Estimate the time required for humidification , the formula is as follows: ； in, Indicates the density of water; S7, moistening the test soil sample according to the acquisition time; S8. Dehumidify the test soil sample according to the acquisition time; Among them, the humidification treatment process of the test soil sample is as follows: (1) Open the water inlet unit, turn on the pump 1, unscrew the water inlet valve 1 and the water inlet valve 2, and add the water required for humidification to the top of the test soil sample; after the water is added, close the pump 1 and the water inlet valve 1, and open the drain valve 1 and the pump 2; (2) Turn on the DC power supply, set the voltage to U0, start humidification, and make the moisture at the top of the test soil sample migrate to the bottom. At the same time, the moisture at the bottom is collected into the water collection tank through the negative plate and the water collection hole, and circulated to the top of the test soil sample through the drainage system unit. After time t, turn off the DC power supply; (3) Close the movable cover on the transparent sealing cover and let the test soil sample stand for more than 24 hours to complete the humidification treatment process; The dehumidification process of the test soil sample is as follows: (1) Close water inlet valve 1, water inlet valve 2 and drain valve 1, and open drain valve 2; (2) Turn on the DC power supply and pump 2 to start dehumidification, so that the moisture on the top of the test soil sample migrates to the bottom. At the same time, the moisture at the bottom is collected into the water collection tank through the negative plate and the water collection hole, and discharged into the external drainage tank through drainage branch pipe 2 and drainage branch pipe 1. At the same time, pay attention to the mass loss of the electronic balance. After time t, turn off the DC power supply; (3) Close the movable cover on the transparent sealing cover and let the test soil sample stand for more than 24 hours to complete the dehumidification process.

Images