A fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device and test method

Abstract

A fine-grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device, comprising an outer ring container for simulating temperature, humidity and wind speed conditions; an annular inner ring container with a multi-cavity membrane structure for applying lateral pressure, the open area formed inside the inner ring container is provided with a lower permeable plate; a sample is arranged above the lower permeable plate, the top surface of the sample is provided with an upper permeable plate, a pressurizing base and a top cover in sequence from bottom to top, a plurality of no-load displacement sensors are arranged on the lower end surface of the top cover, the upper end surface of the pressurizing base is connected to an external pressurizing mechanism, a pressure sensor and a loaded displacement sensor are arranged on the pressurizing base, a temperature, humidity and wind speed sensor is arranged on the inner wall of the outer ring container, and a moisture content sensor is arranged around the sample; various sensors, displacement meters, cameras are connected to a multi-channel data acquisition instrument; the invention also discloses a corresponding test method; more comprehensive evaluation of the changes in soil consolidation and swelling under different dry-wet cycle conditions; and improvement of test efficiency, flexibility, applicability and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of rock and soil mechanics and engineering, and in particular to a fine-grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device and a test method thereof, which are applicable to but not limited to studying the consolidation, swelling and shrinkage and dry-wet cycle characteristics of various types of soil. Background Art

[0002] The property of fine-grained soil that increases in volume due to an increase in water content is called expansion; the property of shrinking in volume due to the loss of water in the soil is called shrinkage. The increase and decrease in water content in fine-grained soil is mainly caused by external factors, such as precipitation, changes in surface water and groundwater, changes in temperature and humidity, etc. The expansion and contraction of fine-grained soil has a great impact on engineering buildings. The expansion and contraction of the soil not only reduces the strength of the soil, but also causes deformation of the soil, leading to the destruction of the building. Slopes composed of fine-grained soil often cause landslides due to the expansion of the soil, which brings harm to the project. Therefore, studying the expansion and contraction of fine-grained soil is of great significance in engineering practice. In engineering construction, structures built on expansive soil with constant water content will not suffer damage caused by expansion and contraction. When the water content of the soil changes, volume expansion in both vertical and horizontal directions will occur immediately. A slight change in water content, only 1% to 2%, is enough to cause harmful expansion. A deep understanding of the expansion and contraction characteristics of fine-grained soil is the key to solving engineering problems caused by the expansion and contraction of fine-grained soil. The swelling and shrinkage of fine-grained soil is greatly affected by its consolidation degree and dry-wet cycle changes. Studying the consolidation and swelling and shrinkage of fine-grained soil under different dry-wet cycle conditions is the key to understanding the swelling and shrinkage of fine-grained soil.

[0003] At present, the relevant test devices all have the following shortcomings:

[0004] (1) The fine-grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device of the present invention is that the consolidation test, swelling test, shrinkage test and dry-wet cycle test of fine-grained soil are all completed separately in different test equipments, and the tests are not continuous, and repeated sampling and loading are required, and the soil is disturbed many times, resulting in large errors in the test results;

[0005] (2) The current expansion test for fine-grained soil only measures the vertical changes of the specimen during the expansion process, but does not measure the horizontal changes;

[0006] (3) Currently, most shrinkage tests for fine-grained soils only measure the shrinkage in the vertical direction of the soil, but cannot measure the real-time volume changes during the shrinkage process;

[0007] (4) At present, most of the swelling and shrinkage test devices for fine-grained soil cannot adjust the size of the lateral pressure and cannot simulate the different stress states of the soil under different engineering conditions. Therefore, it is necessary to design an efficient fine-grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device to systematically complete the consolidation swelling and shrinkage and dry-wet cycle tests of fine-grained soil, measure the consolidation and swelling and shrinkage of the soil under different dry-wet cycle conditions, and thus provide further support for the research on the swelling and shrinkage of fine-grained soil. Summary of the invention

[0008] In order to solve the deficiencies or shortcomings of the prior art, the present invention provides an efficient fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device. The consolidation test, expansion test, contraction test and dry-wet cycle test are completed in the same device, which can more comprehensively reflect the changes in the consolidation and expansion and contraction of the soil under different dry-wet cycle conditions, avoid repeated tests, save test time, reduce the disturbance of the soil during the test, and can control the lateral pressure of the soil, and measure the volume changes of the soil in the vertical and horizontal directions in real time.

[0009] In order to achieve the above-mentioned purpose, the present invention relates to: a fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device, comprising an outer ring container for simulating temperature, humidity and wind speed conditions; the outer ring container is a cavity structure and is provided with an air inlet pipe with a No. 1 valve and an air outlet pipe with a No. 2 valve, the air inlet pipe is connected to a temperature, humidity and wind speed controller, an annular inner ring container for applying lateral pressure is provided on the inner bottom surface of the outer ring container, and the open area formed inside the inner ring container is provided with a lower water-permeable plate; a sample is provided above the lower water-permeable plate, and the top surface of the sample is provided with an upper water-permeable plate, a pressure cover plate in sequence from bottom to top. , a pressurized base and a top cover, a plurality of unloaded displacement sensors (including displacement sensor No. 1, displacement sensor No. 2, displacement sensor No. 3, and displacement sensor No. 4) are arranged on the lower end surface of the top cover, the upper end surface of the pressurized base is connected to the external pressurizing mechanism, a pressure sensor and a loaded displacement sensor are arranged on the pressurized base, a temperature, humidity and wind speed sensor is arranged on the inner wall of the outer ring container, a moisture content sensor is arranged around the sample, the sensor, displacement meter, camera are connected to a multi-channel data acquisition instrument, and the signal of the multi-channel data acquisition instrument is connected to a computer processing system through a data line;

[0010] The inner ring container includes a rigid multi-chamber structure, which includes an upper chamber, a middle chamber and a lower chamber arranged in sequence from top to bottom. The upper chamber, the middle chamber and the lower chamber are all open structures at one end close to the sample and are respectively covered with independent and sealed rubber membranes (including an upper chamber rubber membrane, a middle chamber rubber membrane and a lower chamber rubber membrane). An outer rubber membrane in direct contact with the sample is also arranged between the multi-chamber structure and the sample; the middle chamber is connected to a No. 1 pressure pipe, and the upper chamber and the lower chamber are connected to a No. 2 pressure pipe. The multi-chamber structure can be filled with water to apply lateral pressure to the sample; the outer rubber membrane is in direct contact with the sample, and the rubber membrane expands and contracts with the sample;

[0011] Furthermore, the temperature, humidity and wind speed controller includes a heater for adjusting air temperature, a humidifier for adjusting air humidity and a fan for adjusting air flow rate.

[0012] Furthermore, the upper cavity and the lower cavity are protection cavities, the middle cavity is a measurement cavity, and the height of the middle cavity is not greater than the height of the shrinkage limit of the sample.

[0013] Furthermore, the upper water-permeable plate and the lower water-permeable plate are made of alumina or non-corrosive metal materials, and their permeability coefficients should not be greater than the permeability coefficient of the sample. The diameter of the upper water-permeable plate should be 0.2 to 0.5 mm smaller than the diameter of the sample.

[0014] Furthermore, the moisture content sensor includes three probes, which are evenly spaced around the sample and located between the sample and the rubber membrane. Under the confining pressure applied by the inner circle container, one side is in close contact with the sample to measure the volumetric moisture content of the sample in a measurement range of 0-100%.

[0015] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0016] (1) The consolidation test, expansion test, shrinkage test and dry-wet cycle test of fine-grained soil can be completed in the same test equipment, and the continuity between tests is better; there is no need for repeated sampling and loading, the soil is basically not disturbed during the test, and the test results are more accurate;

[0017] (2) It can more comprehensively evaluate the changes in the consolidation and expansion and contraction properties of fine-grained soil under different drying and wetting cycles, and has broad application prospects;

[0018] (3) Different dry-wet cycle conditions, consolidation pressure and lateral pressure can be set according to test needs. The operation is simple and easy, which improves the test efficiency, flexibility, applicability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a preferred embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the local structure of the multi-cavity structure of a preferred embodiment of the present invention (sample 5 only shows part);

[0021] Figure 3 It is a schematic diagram of the local structure of the rubber membrane of a preferred embodiment of the present invention;

[0022] Figure 4 It is a partial top view of a sample of a preferred embodiment of the present invention;

[0023] In the figure: 1-top cover; 2-pressurized base; 3-pressurized cover plate; 4-upper permeable plate; 5-sample; 6-lower permeable plate; 7-outer container; 8-inner container; 9-No. 1 pressurized pipe; 10-vacuum pump; 11a-No. 1 valve, 11b-No. 2 valve, 11c-No. 3 valve, 11d-No. 4 valve; 12-heating machine; 13-humidifier; 14-fan; 15-temperature, humidity and wind speed controller; 16-multi-channel data acquisition instrument; 17-computer processing system; 18-pressure sensor; 19-load state displacement sensor; 20-no-load state displacement sensor; 20a-No. 1 position 1-displacement sensor, 20b-No. 2 displacement sensor, 20c-No. 3 displacement sensor, 20d-No. 4 displacement sensor; 21-temperature, humidity and wind speed sensor; 22a-No. 1 moisture content sensor probe, 22b-No. 2 moisture content sensor probe, 22c-No. 3 moisture content sensor probe; 23a-No. 1 flow sensor; 23b-No. 2 flow sensor; 24-camera; 25-multi-cavity structure; 26a-upper cavity rubber membrane, 26b-middle cavity rubber membrane, 26c-lower cavity rubber membrane; 26d-outer rubber membrane; 27-upper cavity; 28-middle cavity; 29-lower cavity; 30-No. 2 pressurized pipe. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Embodiment 1:

[0026] like Figures 1-2As shown, a fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device includes an outer ring container 7 for simulating temperature, humidity and wind speed conditions; the outer ring container 7 is a cavity structure and is provided with an air inlet pipe 71 with a No. 1 valve 11a and an air outlet pipe 72 with a No. 2 valve 11b, the air inlet pipe 71 is connected to a temperature, humidity and wind speed controller 15, an annular inner ring container 8 for applying lateral pressure is provided on the inner bottom surface of the outer ring container 7, and the open area formed inside the inner ring container 8 is provided with a lower permeable plate 6; a sample 5 is provided above the lower permeable plate 6, and the top surface of the sample 5 is arranged from bottom to top in order An upper water-permeable plate 4, a pressurizing base 2 and a top cover 1 are provided. A plurality of unloaded displacement sensors 20 are provided on the lower end surface of the top cover 1. The upper end surface of the pressurizing base 2 is connected to an external pressurizing mechanism. A pressure sensor 18 and a loaded displacement sensor 19 are provided on the pressurizing base 2. A temperature, humidity and wind speed sensor 21 is provided on the inner wall of the outer ring container 7. A moisture content sensor 22 is provided around the sample 5. Various sensors, displacement meters and cameras 24 are connected to a multi-channel data acquisition instrument 16. The signals of the multi-channel data acquisition instrument 16 are connected to a computer processing system 17 via a data line.

[0027] Preferably, the upper water-permeable plate 4 and the lower water-permeable plate 6 are made of alumina or non-corrosive metal materials, and their permeability coefficients should not be greater than the permeability coefficients of the sample, and the diameter of the upper water-permeable plate should be 0.2 to 0.5 mm smaller than the diameter of the sample;

[0028] Preferably, the accuracy of the loaded displacement sensor 19, the first displacement sensor 20a, the second displacement sensor 20b, the third displacement sensor 20c, and the fourth displacement sensor 20d is 0.2% of the full scale.

[0029] Please refer to Figure 2 , Figure 3 The inner container 8 includes a rigid multi-chamber structure 25, which includes an upper chamber 27, a middle chamber 28 and a lower chamber 29 arranged from top to bottom. The upper chamber 27, the middle chamber 28 and the lower chamber 29 are all open structures at one end close to the sample 5 and are each covered with an independent and sealed rubber membrane. An outer rubber membrane 26d in direct contact with the sample 5 is also provided between the multi-chamber structure and the sample 5, and the outer rubber membrane 26d expands and contracts with the sample 5; the middle chamber 28 is connected to the No. 1 pressure pipe 9 with a built-in or external pressure pump, and the upper chamber 27 and the lower chamber 29 are connected to the No. 2 pressure pipe 30. The multi-chamber structure can be filled with water to apply lateral pressure to the sample. Each chamber is connected to the No. 1 pressure pipe 9 (built-in or external pressure pump), and can be filled with water to apply lateral pressure to the sample. The upper chamber 27 and the lower chamber 29 are protection chambers, and the middle chamber 28 is a measuring chamber. The height of the middle chamber is not greater than the height of the sample's shrinkage limit.

[0030] Preferably, the temperature, humidity and wind speed controller 15 includes a heater 12 for adjusting air temperature, a humidifier 13 for adjusting air humidity and a fan 14 for adjusting air flow rate.

[0031] Please refer to Figure 4 The moisture content sensor 22 includes three probes: moisture content sensor probe No. 1 22a, moisture content sensor probe No. 22b, and moisture content sensor probe No. 3 22c, which are equally spaced around the sample 5 and located between the sample 5 and the rubber membrane 26. Under the confining pressure applied by the inner circle container 8, one side is in close contact with the sample 5 to measure the volumetric moisture content of the sample. The measurement range is 0-100% (such as Tiannuo Huanneng TDR-6A soil temperature and humidity sensor).

[0032] Preferably, the multi-channel data acquisition instrument 16 can sample multiple channels in parallel and can simultaneously correspond to multiple pressure sensors 18, load state displacement sensors 19, unload state displacement sensors 20, moisture content sensors 22, temperature, humidity and wind speed sensors 21, flow sensor No. 1 23a, flow sensor No. 2 23b and camera 24 for data acquisition and communication transmission (commercially available multi-channel data acquisition instruments have no less than 32 channels, such as AT4516 multi-channel data acquisition instrument).

[0033] Place the sample 5 in the circular position inside the inner circle container 8 of the device, and place permeable stones and filter paper on the top and bottom of the sample, in the order of lower permeable plate 6, filter paper, sample 5, filter paper, and upper permeable plate 4. Place the pressurized cover plate 3 and pressurized base 2 on the upper permeable plate 4 in sequence, and cover it with the top cover 1, which is connected to the external pressurization device. The pipe on one side of the outer circle container 7 is connected to the temperature, humidity and wind speed controller 15 as an air inlet, and the pipe on the other side is connected to the vacuum pump 10 as an air outlet. The pipes on both sides of the inner circle container 8 are connected to the No. 1 pressurized pipe 9. The camera 24 is installed on the top cover 1. The moisture content sensor 22 is placed between the rubber membrane 26 and the sample 5, and is in close contact with the sample 5.

[0034] Embodiment 2:

[0035] The sample to be tested is yellow-brown, hard plastic, and contains black iron-manganese nodules. It is a ring-shaped sample with a diameter of 61.8 mm and a height of 20 mm cut from the original soil. The moisture content is 17.0% and the dry density is 1.77 g / cm 3 .

[0036] Step 1: Place the device on the operating platform and connect each sensor to the multi-channel data acquisition device 16. The multi-channel data acquisition device 16 is connected to the computer processing system 17.

[0037] Step 2: Place a lower water-permeable plate 6 in the container, place the sample 5 on the lower water-permeable plate 6, place a thin filter paper between the sample 5 and the lower water-permeable plate 6, and place the thin filter paper and the upper water-permeable plate 4 on the sample 5 in sequence;

[0038] Step 3: Open valve No. 3 11c and valve No. 4 11d, fill the inner circle container with water, and keep the volume of water in the inner circle container unchanged according to the test conditions.

[0039] Step 4: Place the pressurized cover plate 3 and the pressurized base 2 on the upper permeable plate 4 so that the centers of the pressurized cover plate 3 and the pressurized base 2 are aligned.

[0040] Step 5: Connect the device to the pressurizing device, determine the consolidation pressures to be applied, and start consolidation. The height change of the sample is recorded by the load state displacement sensor 19, and the pressure sensor 18 records the applied pressure. After applying each level of pressure, when the deformation reaches 0.01mm per hour, the height change of the sample is measured as the stability standard. Pressurize step by step according to this step until the test is completed.

[0041] The above steps can complete the consolidation test.

[0042] Embodiment 3:

[0043] Step 1: Same as step 1 in Example 2.

[0044] Step 2: Same as step 2 in Example 2.

[0045] Step 3: Same as step 3 in Example 2.

[0046] Step 4: Cover the top cover 1 to make the first displacement sensor 20a, the second displacement sensor 20b, and the third displacement sensor 20c contact the upper water-permeable plate 4.

[0047] Step 5: Open valve No. 11a, close valve No. 2 11b, inject pure water into the container from bottom to top, and keep the water surface 5mm higher than the sample. The difference in displacement meter readings within 2 hours does not exceed 0.01mm, and the expansion is stable.

[0048] The above steps can complete the no-load expansion test.

[0049] Embodiment 4:

[0050] Step 1: Same as step 1 in Example 2.

[0051] Step 2: Same as step 2 in Example 2.

[0052] Step 3: Open valves 11c and 11d, fill the inner circle container with water, set a certain water pressure according to the test conditions, apply lateral pressure to the sample, and the water pressure in the upper and lower protection chambers is slightly greater than the water pressure in the middle chamber.

[0053] Step 4: Same as step 4 in Example 3.

[0054] Step 5: Open valve 11a and valve 11b. According to the test conditions, set the temperature, humidity and wind speed of the air. The pipe on one side connected to the temperature, humidity and wind speed controller 15 is the air inlet, and the pipe on the other side connected to the vacuum pump 10 is the air outlet to keep the air flowing inside the device.

[0055] During the test, the temperature, humidity and wind speed sensor 21 records the temperature, humidity and wind speed of the air actually passing through the device, the moisture content sensor 22 records the change in moisture content of the sample, the no-load displacement sensor 20 records the change in the vertical height of the sample, the camera 24 records the development of cracks on the surface of the sample, the No. 1 flow sensor 23a arranged in the No. 1 pressurized pipe 9 and the No. 2 flow sensor 23b arranged in the No. 2 pressurized pipe 30 record the radial volume change of the sample, and calculate the radius value of the sample at any time.

[0056] Calculation formulas involved in the test:

[0057] During the test, the radius value r of the sample at any time t :

[0058]

[0059] r t ——The radius of the sample at time t, cm;

[0060] r0——initial radius of the sample, cm;

[0061] ΔV——Volume change of the middle cavity measuring cavity within time t, cm 3 ;

[0062] h m ——Height of the middle cavity measuring cavity, cm.

[0063] Embodiment 5:

[0064] After carrying out Example 2, remove the pressurized base 2 and the pressurized cover plate 3, carry out Step 4 and Step 5 in Example 3, then open valve No. 11a and valve No. 2 11b to discharge the moisture in the device, and then carry out Step 5 in Example 4.

[0065] The above steps can be implemented to complete the consolidation expansion and contraction integrated test of the sample.

[0066] Embodiment 6:

[0067] While carrying out Example 4, the temperature, humidity and wind speed of the air at the air inlet are changed, and dry-wet cycle tests of the samples under different conditions and times can be carried out.

[0068] During the expansion test, the changes in the vertical and horizontal directions of the soil during the expansion process can be measured in real time; during the contraction test, the changes in the vertical direction and circumference of the soil during the contraction process can be measured in real time to obtain the volume change of the soil during the contraction process; during the expansion and contraction test of fine-grained soil, the size of the lateral pressure can be adjusted to simulate the ground stress levels at different depths.

[0069] The above-mentioned efficient fine-grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device is used, which can more comprehensively reflect the structural changes of the soil during the dry-wet cycle, avoid repeated tests, and reduce the test time. The device has a simple design structure, easy operation, good stability, each group of components is durable, not easy to wear, strong practicality, high precision, and one or more different test paths can be set according to the test needs. The operation is simple and easy, which significantly improves the test efficiency, flexibility, applicability and accuracy. It can more comprehensively evaluate the changes in soil moisture content, swelling and shrinkage, consolidation characteristics and surface crack development under different dry-wet cycle conditions, and has broad application prospects.

[0070] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A test method for a fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device, characterized in that: Including consolidation test method, no-load expansion test method, sample dry-wet cycle test method and consolidation expansion-contraction integrated test method; The fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device used in the above test method comprises an outer ring container (7) for simulating temperature, humidity and wind speed conditions; the outer ring container (7) is a cavity structure and is provided with an air inlet pipe (71) with a No. 1 valve (11a) and an air outlet pipe (72) with a No. 2 valve (11b), the air inlet pipe (71) is connected to a temperature, humidity and wind speed controller (15), an annular inner ring container (8) for applying lateral pressure is provided on the inner bottom surface of the outer ring container (7), and the open area formed inside the inner ring container (8) is provided with a lower water-permeable plate (6); a sample (5) is provided above the lower water-permeable plate (6), and the top surface of the sample (5) is arranged in order from bottom to top. An upper water-permeable plate (4), a pressurizing base (2) and a top cover (1) are provided. A plurality of unloaded displacement sensors (20) are provided on the lower end surface of the top cover (1). The upper end surface of the pressurizing base (2) is connected to an external pressurizing mechanism. A pressure sensor (18) and a loaded displacement sensor (19) are provided on the pressurizing base (2). A temperature, humidity and wind speed sensor (21) is provided on the inner wall of the outer ring container (7). A moisture content sensor (22) is provided around the sample (5). Various sensors, displacement meters and cameras (24) are connected to a multi-channel data acquisition instrument (16). The signals of the multi-channel data acquisition instrument (16) are connected to a computer processing system (17) via a data line. The inner ring container (8) includes a rigid multi-chamber structure (25), which includes an upper chamber (27), a middle chamber (28) and a lower chamber (29) arranged in sequence from top to bottom. The upper chamber (27), the middle chamber (28) and the lower chamber (29) are all open structures at one end close to the sample (5) and are each covered with an independent and sealed rubber film. An outer rubber film (26d) in direct contact with the sample (5) is also provided between the multi-chamber structure and the sample (5); the middle chamber (28) is connected to a No. 1 pressurized pipe (9), and the upper chamber (27) and the lower chamber (29) are connected to a No. 2 pressurized pipe (30). The multi-chamber structure can be filled with water to apply lateral pressure to the sample; the temperature, humidity and wind speed controller (15) includes a heater (12) for adjusting air temperature, a humidifier (13) for adjusting air humidity and a fan (14) for adjusting air flow rate; The sample dry-wet cycle test method comprises the following steps: Step 1: Place the device on an operating platform, connect each sensor to a multi-channel data acquisition device (16); the multi-channel data acquisition device (16) is connected to a computer processing system (17); Step 2: Place a lower water-permeable plate (6) in a container, place the sample (5) on the lower water-permeable plate (6), place a thin filter paper between the sample (5) and the lower water-permeable plate (6), and place the thin filter paper and the upper water-permeable plate (4) on the sample (5) in sequence; Step 3: Open the No. 3 valve (11c) on the No. 1 pressurized pipe (9) and the No. 4 valve (11d) on the No. 2 pressurized pipe (30), fill the inner circle container with water, set a certain water pressure according to the test conditions, apply lateral pressure to the sample, and the water pressure in the upper chamber (27) and the lower chamber (29) is slightly greater than the water pressure in the middle chamber; Step 4: Cover the top cover (1) to make the unloaded displacement sensor (20) contact the upper water-permeable plate (4); Step 5: Open valve No. 1 (11a) and valve No. 2 (11b); set the temperature, humidity and wind speed of the air according to the test conditions, the pipe on one side connected to the temperature, humidity and wind speed controller (15) is the air inlet, and the pipe on the other side connected to the vacuum pump (10) is the air outlet, so as to maintain air circulation inside the device; During the test, the temperature, humidity and wind speed sensor (21) records the temperature, humidity and wind speed of the air actually passing through the device, the moisture content sensor (22) records the change in moisture content of the sample, the load-free displacement sensor (20) records the change in the vertical height of the sample, the camera (24) arranged on the top cover (1) records the development of cracks on the surface of the sample, the No. 1 flow sensor (23a) arranged in the No. 1 pressurized pipe (9) and the No. 2 flow sensor (23b) arranged in the No. 2 pressurized pipe (30) record the change in radial volume of the sample, calculate the radius value of the sample at any time, and change the temperature, humidity and wind speed of the air at the air inlet, so as to carry out dry-wet cycle tests of the sample under different conditions and times; Calculation formulas involved in the test: During the test, the radius value r of the sample at any time t : r t ——The radius of the sample at time t, cm; r0——initial radius of the sample, cm; ΔV——Volume change of the middle cavity measuring cavity within time t, cm 3 ; h m ——Height of the middle cavity measuring cavity, cm; π——pi.

2. The test method of the fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device according to claim 1 is characterized in that: The upper cavity (27) and the lower cavity (29) are protection cavities, and the middle cavity (28) is a measurement cavity. The height of the middle cavity is not greater than the height of the shrinkage limit of the sample.

3. The test method of the fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device according to claim 1 is characterized in that: The moisture content sensor (22) comprises three probes which are equally spaced around the sample (5) and are located between the sample (5) and the rubber membrane (26). Under the confining pressure applied by the inner container (8), one side of the probe is in close contact with the sample (5) to measure the volumetric moisture content of the sample in a measurement range of 0-100%.

4. The test method of the fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device according to claim 1 is characterized in that: The consolidation test method comprises the following steps: Step 1: Place the device on an operating platform, connect each sensor to a multi-channel data acquisition device (16); the multi-channel data acquisition device (16) is connected to a computer processing system (17); Step 2: Place a lower water-permeable plate (6) in a container, place the sample (5) on the lower water-permeable plate (6), place a thin filter paper between the sample (5) and the lower water-permeable plate (6), and place the thin filter paper and the upper water-permeable plate (4) on the sample (5) in sequence; Step 3: Open valve No. 3 (11c) on pressure pipe No. 1 (9) and valve No. 4 (11d) on pressure pipe No. 2 (30), fill the inner container with water, and keep the volume of water in the inner container (8) unchanged according to the test conditions; Step 4: placing the pressurized cover plate (3) and the pressurized base (2) on the upper water-permeable plate (4) so ​​that the pressurized cover plate (3) and the pressurized base (2) are aligned in center; Step 5: Connect the device to the pressurizing device, determine the consolidation pressures to be applied at each level, and start consolidation; record the height change of the sample through the load state displacement sensor (19), and the pressure sensor (18) records the applied pressure. After applying each level of pressure, when the deformation reaches 0.01 mm per hour, measure the height change of the sample as a stability standard, and pressurize step by step according to this step until the test is completed.

5. The test method of the fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device according to claim 1 is characterized in that: The no-load expansion test method comprises the following steps: Step 1: Place the device on an operating platform, connect each sensor to a multi-channel data acquisition device (16); the multi-channel data acquisition device (16) is connected to a computer processing system (17); Step 2: Place a lower water-permeable plate (6) in a container, place the sample (5) on the lower water-permeable plate (6), place a thin filter paper between the sample (5) and the lower water-permeable plate (6), and place the thin filter paper and the upper water-permeable plate (4) on the sample (5) in sequence; Step 3: Open the No. 3 valve (11c) on the No. 1 pressurized pipe (9) and the No. 4 valve (11d) on the No. 2 pressurized pipe (30), fill the inner circle container with water, and keep the volume of water in the inner circle container unchanged according to the test conditions; Step 4: Cover the top cover (1) to make the unloaded displacement sensor (20) contact the upper water-permeable plate (4); Step 5: Open valve No. 1 (11a), close valve No. 2 (11b), inject pure water into the container from bottom to top, and keep the water surface 5mm higher than the sample. The reading difference of the displacement sensor (20) in the unloaded state does not exceed 0.01mm within 2 hours, and the expansion is stable.

6. The test method of the fine-grained soil consolidation expansion and contraction and dry-wet cycle integrated test device according to claim 1 is characterized in that: The consolidation expansion and contraction integrated test method comprises the following steps: Step 1: Place the device on an operating platform, connect each sensor to a multi-channel data acquisition device (16); the multi-channel data acquisition device (16) is connected to a computer processing system (17); Step 2: Place a lower water-permeable plate (6) in a container, place the sample (5) on the lower water-permeable plate (6), place a thin filter paper between the sample (5) and the lower water-permeable plate (6), and place the thin filter paper and the upper water-permeable plate (4) on the sample (5) in sequence; Step 3: Open the No. 3 valve (11c) on the No. 1 pressurized pipe (9) and the No. 4 valve (11d) on the No. 2 pressurized pipe (30), fill the inner circle container with water, and keep the volume of water in the inner circle container unchanged according to the test conditions; Step 4: placing the pressurized cover plate (3) and the pressurized base (2) on the upper water-permeable plate (4) so ​​that the pressurized cover plate (3) and the pressurized base (2) are aligned in center; Step 5: Connect the device to the pressurizing device, determine the consolidation pressures to be applied at each level, and start consolidation; record the height change of the sample by the load state displacement sensor (19), and record the applied pressure by the pressure sensor (18); after applying each level of pressure, when the deformation reaches 0.01 mm per hour, measure the height change of the sample as a stability standard, and pressurize step by step according to this step until the test is completed; Step 6: Remove the pressurized base (2) and the pressurized cover plate (3), cover the top cover (1), make the No. 1 displacement sensor (20a), the No. 2 displacement sensor (20b), and the No. 3 displacement sensor (20c) contact the upper permeable plate (4), open the No. 1 valve (11a), close the No. 2 valve (11b), inject pure water into the container from bottom to top, and keep the water surface 5mm higher than the sample. The difference in the displacement meter readings within 2 hours does not exceed 0.01mm, and the expansion is stable; then open the No. 1 valve (11a) and the No. 2 valve (11b) to discharge the moisture in the device. According to the test conditions, set the temperature, humidity and wind speed of the air. The pipe on one side connected to the temperature, humidity and wind speed controller (15) is the air inlet, and the pipe on the other side connected to the vacuum pump (10) is the air outlet to maintain air circulation inside the device; During the test, the temperature, humidity and wind speed sensor (21) records the temperature, humidity and wind speed of the air actually passing through the device, the moisture content sensor (22) records the change in moisture content of the sample, the load-free displacement sensor (20) records the change in the vertical height of the sample, the camera (24) arranged on the top cover (1) records the development of cracks on the surface of the sample, the No. 1 flow sensor (23a) arranged in the No. 1 pressurized pipe (9) and the No. 2 flow sensor (23b) arranged in the No. 2 pressurized pipe (30) record the change in the radial volume of the sample, and the radius value of the sample at any time is calculated; Calculation formulas involved in the test: During the test, the radius value r of the sample at any time t : r t ——The radius of the sample at time t, cm; r0——initial radius of the sample, cm; ΔV——Volume change of the middle cavity measuring cavity within time t, cm 3 ; h m ——Height of the middle cavity measuring cavity, cm.

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