A method and apparatus for determining wetting deformation of a soil

Abstract

The application discloses a kind of test device and its using method for determining soil body humidification deformation, the device includes sealed container, ring knife sample consolidation container placed in the bottom of sealed container, vertical loading device, micrometer and saturated salt solution storage device;The upper portion of the ring knife sample consolidation container is connected with vertical loading rod, and the vertical loading device is circumscribed to the loading rod, and the micrometer is installed on the loading rod;The saturated salt solution storage device is communicated with the bottom of sealed container.The application injects saturated salt solution in the bottom of closed container, accurately controls the suction of soil sample by using saturated salt solution vapor equilibrium, gradually humidifies soil sample by replacing saturated salt solution type under the condition that upper load remains constant, and determines the humidification deformation of soil under different humidification degrees by using the same sample;Meanwhile, the application can also gradually increase vertical load while keeping saturated salt solution type unchanged, to determine the compression deformation characteristics of soil under certain suction condition.

Description

[0001] The present application is a divisional application, the original application is entitled "Test device for measuring wetting deformation of soil body and its use method", the application number is 202110844769.1, and the application date is July 26, 2021. TECHNICAL FIELD

[0002] The present application belongs to the technical field of geotechnical engineering test instruments and equipment, and relates to a geotechnical engineering test device, in particular to a sample device for measuring wetting deformation of soil body and its use method. BACKGROUND

[0003] In the southern region of China, heavy rainfall occurs during the plum rain season, and rainwater penetrates into the soil body of slopes, roadbeds, embankments, etc., causing the water content of the soil body to gradually increase. Studies have shown that under the influence of infiltration, rainfall, evaporation and groundwater, water migration and humidity redistribution occur in the roadbed, and the water content increases by 2% to 10% compared to the construction time. Under the coupling effect of wetting and rainfall, the roadbed, embankment, etc. will deform and cause the road surface structure to crack, affecting driving safety. Therefore, it is necessary to study the deformation characteristics of the soil body under the coupling effect of wetting and rainfall, to provide a theoretical basis for the deformation prediction of roadbeds, embankments, and the prevention and control of natural disasters such as landslides.

[0004] Currently, strength is often used as an indicator in the design of roadbeds, embankments, etc., and less attention is paid to wetting deformation. In addition, the water content is generally low during the rolling construction of roadbeds, embankments, etc., and there is a large suction in the soil body. The current pressure plate apparatus is only suitable for measuring the wetting deformation of soil body with low suction, and there is currently no related instrument and equipment that can accurately measure the wetting deformation of soil body with high suction. Therefore, it is of great significance to develop a test device that can measure the deformation of soil body under the coupling effect of load and wetting, to accurately evaluate the wetting deformation of soil body and predict the settlement of roadbeds. SUMMARY

[0005] The technical problem to be solved is to overcome the shortcomings of the prior art, to measure the deformation of soil body under the coupling effect of load and wetting, and to measure the wetting deformation of soil body under different wetting degrees using the same sample without disassembling the sample. The present application provides a test device for measuring wetting deformation of soil body and its use method.

[0006] Technical solution: the test device for determining soil wetting deformation, the test device comprises a sealed container, a ring knife sample consolidation container, a vertical loading device, a micrometer and a saturated salt solution storage device; the ring knife sample consolidation container sequentially places water-permeable stones, filter paper, a ring knife sample, filter paper, water-permeable stones, a pressure transmission plate, the pressure transmission plate is connected with a vertical loading rod, the loading rod is connected with the vertical loading device, and the loading rod is provided with a micrometer; the saturated salt solution storage device is connected with the bottom of the sealed container through a plastic hose, and the inflow and outflow of the saturated salt solution are controlled through a three-way valve; the test device for determining soil wetting deformation applies vertical load on the upper part of the ring knife sample through the pressure transmission plate, changes different types of saturated salt solutions, accurately controls the suction (water content) of the soil sample by using the vapor equilibrium of the saturated salt solution, makes the sample wet gradually, determines the wetting deformation of the soil under different wetting degrees by using the same sample, and realizes the determination of the wetting deformation of the soil in the high suction (low water content) section; the test device for determining soil wetting deformation can gradually increase the vertical load under the condition that the type of the saturated salt solution is unchanged, and determine the compression deformation characteristics of the soil under a certain suction (water content) condition.

[0007] Preferably, the sealed container is composed of a base with a cylindrical protrusion at the center, a cylindrical plexiglass sealing cavity and a cover plate, the diameter of the cylindrical base is the same as that of the ring knife sample consolidation container, and the height is 5-10 cm; the bottom of the sealed container is injected with saturated salt solution, and the liquid level is slightly lower than the top surface of the cylindrical base.

[0008] Preferably, the bottom of the ring knife sample consolidation container and the pressure transmission plate are uniformly distributed with air permeable holes, so that the bottom and the top of the ring knife sample can be in contact with the saturated vapor in the sealed container, and the ring knife sample reaches vapor equilibrium.

[0009] Preferably, the type of the saturated salt solution is one or more of potassium sulfate, sodium sulfate, potassium chloride, sodium chloride, potassium iodide, sodium bromide, potassium carbonate, magnesium chloride, acetic acid, lithium chloride and lithium bromide; the suction values corresponding to the above-mentioned saturated salt solutions are 3.29, 12.9, 21.82, 38.0, 48.42, 71.12, 113.5, 149.51, 198.14, 286.7 and 367.54 MPa.

[0010] Preferably, the ring knife sample consolidation container sequentially places water-permeable stones, filter paper, a ring knife sample, filter paper and water-permeable stones.

[0011] Preferably, the vertical loading device can be any one of lever loading or air pressure loading.

[0012] Preferably, the bottom of the sealed container is connected with the saturated salt solution storage container through a plastic hose, and the inflow and outflow of the saturated salt solution are controlled through a three-way valve.

[0013] Preferably, the test device for determining the wetting deformation of soil can realize the following functions:

[0014] (1) By replacing different kinds of saturated salt solution while keeping the vertical load constant, the wetting deformation of soil under the coupling of load and wetting is determined by using the vapor equilibrium of saturated salt solution to accurately control the suction (water content) of the sample and wet the sample step by step, and the wetting deformation of soil under different wetting degrees can be determined by using the same sample.

[0015] (2) The saturated salt solution is injected at the bottom of the sealed container, the suction (water content) of the sample is controlled by using the vapor equilibrium of the saturated salt solution, and then the vertical load is gradually increased to determine the compression deformation characteristics of the soil under a certain suction (water content) condition, and the compression index and resilience index of the soil under a specific water content condition are obtained.

[0016] The use method of any of the above-mentioned test devices for determining the wetting deformation of soil comprises the following steps:

[0017] Step 1, open the sealed container, place the cutting ring sample consolidation container on the cylindrical base in the center of the sealed container and align it with the center of the cylindrical base;

[0018] Step 2, determine the water content of the soil sample, then place the permeable stone, filter paper, cutting ring sample, filter paper, and permeable stone in the cutting ring sample consolidation container in order, place the pressure transmission plate on the top of the permeable stone, install the cylindrical organic glass sealing cavity and the cover plate in order, and tightly contact the loading rod with the pressure transmission plate;

[0019] Step 3, install the dial gauge on the pressure transmission rod and contact the expansion needle of the dial gauge with the cover plate, adjust the dial gauge pointer to zero, start the vertical loading device to apply a predetermined load to the sample, record the dial gauge reading, and perform the wetting deformation test after the reading is stable;

[0020] Step 4, calculate the initial suction of the sample according to the water content of the sample combined with the soil water characteristic curve of the sample, compare the calculated initial suction with the suction of various saturated salt solutions, pour the saturated salt solution with a suction value slightly lower than the calculated initial suction into the saturated salt solution storage container, open the three-way valve and the exhaust valve to inject the saturated salt solution into the sealed container until the liquid level is slightly lower than the top surface of the cylindrical base, close the three-way valve and the exhaust valve, record the dial gauge reading, and keep the reading stable.

[0021] Step 5, open the three-way valve and the exhaust valve, so that the sealed container is communicated with the saturated salt solution storage container, and saturated salt solution in the sealed container is discharged; then saturated salt solution with lower suction is injected into the sealed container through the saturated salt solution storage container and the three-way valve, until the liquid level is slightly lower than the top surface of the cylindrical base, the three-way valve and the exhaust valve are closed, the dial gauge reading is recorded until the reading remains stable, the above steps are repeated, and the suction is gradually reduced until the wetting deformation is stable under the lowest suction;

[0022] Step 6, open the three-way valve and the exhaust valve, so that the sealed container is communicated with the saturated salt solution storage container, and saturated salt solution in the sealed container is discharged; then steam-free water is injected into the sealed container, and the ring knife sample is submerged, and the dial gauge reading is recorded to determine the wetting deformation of the sample under the water immersion condition.

[0023] Beneficial effects: (1) the present application can apply different vertical pressures to the soil sample, simulate wetting of the soil under different overburden loads, and accurately control the suction (water content) of the soil sample through saturated salt solution vapor equilibrium, so that the wetting deformation of the soil under different wetting degrees is determined by using the same sample without disassembling the sample, and the deformation law of the soil under the coupling action of load and wetting is determined; (2) in the present application, the saturated salt solution is used to control the suction, different types of saturated salt solution are replaced to realize step-by-step wetting of the sample, the wetting deformation of the soil in the high suction (low water content) range can be determined, and the deficiency that the pressure plate instrument cannot determine the wetting deformation of the soil in the high suction range is made up; (3) in the present application, the suction (water content) of the sample can be controlled by the vapor equilibrium of the saturated salt solution, the sample is loaded step by step under the condition that the suction (water content) is kept constant, the compression deformation characteristics of the soil under a certain suction (water content) condition are determined, and the compression index, the resilience index and other indexes of the soil under low water content condition are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the direct shear sample device of the dry-wet cycle test according to the present application;

[0025] wherein, 1 is a sealed container, 2 is a ring knife sample consolidation container, 3 is a loading rod, 4 is a dial gauge, 5 is a saturated salt solution, 6 is a water-permeable stone, 7 is filter paper, 8 is a ring knife sample, 9 is a pressure transmission plate, 10 is a water-permeable hole at the bottom of the ring knife sample consolidation container, 11 is a water-permeable hole of the pressure transmission plate, 12 is a plastic hose, 13 is a saturated salt solution storage container, 14 is a three-way valve, 15 is a saturated salt solution storage container, 16 is a sealed container base, 17 is a cylindrical organic glass sealed cavity, 18 is a cover plate, and 19 is an exhaust valve. DETAILED DESCRIPTION

[0026] The following examples further illustrate the present application but should not be construed as limiting the application. Modifications and adaptations of the method, steps or conditions of the application described herein are within the skill of the art and, in light thereof, the application should not be construed as limited to the application described herein.

[0027] The technical means used in the examples are conventional ones known to those skilled in the art, unless otherwise specified.

[0028] Example 1

[0029] The test device for measuring the wetting deformation of soil body comprises a sealed container 1, a ring knife sample consolidation container 2 placed at the bottom of the sealed container, a vertical loading device, a micrometer 4, saturated salt solution storage devices 13, 15; the ring knife sample consolidation container sequentially contains water-permeable stones 6, filter paper 7, ring knife sample 8, filter paper 7, water-permeable stones 6, and a pressure transmission plate 9, the pressure transmission plate 9 is connected with a vertical loading rod 3, the vertical loading rod 3 is connected with the vertical loading device, and the vertical loading rod 3 is installed with the micrometer 4; the saturated salt solution storage devices 13, 15 are communicated with the bottom of the sealed container 1 through a plastic hose 12, and the inflow and outflow of the saturated salt solution are controlled through a three-way valve 14; the test device for measuring the wetting deformation of soil body applies the vertical load on the upper part of the ring knife sample 8 through the pressure transmission plate 9, changes the types of the saturated salt solution to accurately control the suction (water content) of the soil sample through the vapor equilibrium of the saturated salt solution, and measures the wetting deformation of the soil body under different wetting degrees by using the same sample, so as to measure the wetting deformation of the soil body in the high suction (low water content) section; the test device for measuring the wetting deformation of soil body can gradually increase the vertical load under the condition that the types of the saturated salt solution are unchanged, and measure the compression deformation characteristics of the soil body under a certain suction (water content) condition.

[0030] The sealed container 1 is composed of a base 16 with a cylindrical protrusion at the center, a cylindrical plexiglass sealing cavity 17, and a cover plate 18, the diameter of the cylindrical base 16 is the same as that of the ring knife sample consolidation container 2, and the height is 5-10 cm; the saturated salt solution 5 is injected into the bottom of the sealed container 1, and the liquid level is slightly lower than the top surface of the cylindrical base 16.

[0031] The bottom of the ring knife sample consolidation container 2 and the pressure transmission plate 9 are uniformly distributed with air-permeable holes, so that the bottom and the top of the ring knife sample can be in contact with the saturated vapor in the sealed container, and the ring knife sample can reach vapor equilibrium.

[0032] The saturated salt solution is one or more of potassium sulfate, sodium sulfate, potassium chloride, sodium chloride, potassium iodide, sodium bromide, potassium carbonate, magnesium chloride, acetic acid, lithium chloride, and lithium bromide; and the corresponding suction values of the saturated salt solutions are 3.29, 12.9, 21.82, 38.0, 48.42, 71.12, 113.5, 149.51, 198.14, 286.7, and 367.54 MPa, respectively.

[0033] The ring knife sample consolidation container 2 is sequentially placed with water-permeable stones, filter paper, a ring knife sample, filter paper, and water-permeable stones.

[0034] The vertical loading device can be any one of a lever loading device or an air pressure loading device.

[0035] The bottom of the sealed container 1 is connected to saturated salt solution storage containers 13 and 15 through plastic hoses 12, and the inflow and outflow of the saturated salt solution is controlled through a three-way valve 14.

[0036] The test device for measuring the wetting deformation of soil bodies can achieve the following functions:

[0037] (1) By replacing different types of saturated salt solutions while keeping the vertical load constant, the suction (water content) of the sample is accurately controlled using the vapor equilibrium of the saturated salt solution to gradually wet the sample, and the wetting deformation of the soil body under the coupling action of the load and wetting is measured, and the wetting deformation of the soil body under different wetting degrees can be measured using the same sample.

[0038] (2) The saturated salt solution is injected into the bottom of the sealed container, the suction (water content) of the sample is controlled using the vapor equilibrium of the saturated salt solution, and then the vertical load is gradually increased to measure the compression deformation characteristics of the soil body under a certain suction (water content) condition, and obtain the compression index and resilience index of the soil body under a specific water content condition.

[0039] The test device for measuring the wetting deformation of soil bodies is used to measure the wetting deformation characteristics of the same sample under different wetting degrees, and the method comprises the following steps:

[0040] Step 1: Open the sealed container 1, place the ring knife sample consolidation container 2 on the cylindrical base 16 in the center of the sealed container 1 and align it with the center of the cylindrical base 16.

[0041] Step 2: Measure the water content of the soil sample, then sequentially place water-permeable stones 6, filter paper 7, a ring knife sample 8, filter paper 7, and water-permeable stones 6 in the ring knife sample consolidation container 2, place a pressure transmission plate 9 on the top of the water-permeable stones, and sequentially install a cylindrical organic glass sealing cavity 17 and a cover plate 18, and tightly contact the loading rod 3 with the pressure transmission plate 9.

[0042] Step 3, install the dial gauge 4 on the pressure transmission rod 3 and make the dial gauge 4 contact with the cover plate 18, adjust the dial gauge 4 to zero, start the vertical loading device to apply a predetermined load on the sample, record the reading of the dial gauge 4, and then carry out the wetting deformation test after the reading is stable;

[0043] Step 4, calculate the initial suction of the sample according to the water content of the sample combined with the soil-water characteristic curve of the sample, compare the calculated initial suction with the suction of various saturated salt solutions, pour the saturated salt solution with a suction value slightly lower than the calculated initial suction into the saturated salt solution storage container 13, open the three-way valve 14 and the exhaust valve 19 to inject the saturated salt solution into the sealed container 1 until the liquid level is slightly lower than the top surface of the cylindrical base 16, close the three-way valve 14 and the exhaust valve 19, and record the reading of the dial gauge 4 until the reading remains stable;

[0044] Step 5, open the three-way valve 14 and the exhaust valve 19 to connect the sealed container 1 with the saturated salt solution storage container 15, and then discharge the saturated salt solution in the sealed container 1; after that, inject the saturated salt solution with a lower suction level into the sealed container 1 through the saturated salt solution storage container 13 and the three-way valve 14 until the liquid level is slightly lower than the top surface of the cylindrical base 16, close the three-way valve 14 and the exhaust valve 19, and record the reading of the dial gauge 4 until the reading remains stable, repeat the above steps to gradually reduce the suction until the wetting deformation is stable under the lowest suction level;

[0045] Step 6, open the three-way valve 14 and the exhaust valve 19 to connect the sealed container 1 with the saturated salt solution storage container 15, and then discharge the saturated salt solution in the sealed container 1; after that, inject the non-steam water into the sealed container 1 to submerge the ring knife sample, record the reading of the dial gauge 4, and measure the wetting deformation of the sample under the immersion condition.

[0046] The test device for measuring the wetting deformation of soil bodies is used for measuring the compression deformation characteristics of soil bodies under a certain suction condition, and includes the following steps:

[0047] Step 1, open the sealed container 1, place the ring knife sample consolidation container 2 on the cylindrical base 16 in the center of the sealed container 1 and align with the center of the cylindrical base 16;

[0048] Step 2, place the water-permeable stones 6, filter paper 7, ring knife sample 8, filter paper 7, and water-permeable stones 6 in the ring knife sample consolidation container 2 in sequence, place the pressure transmission plate 9 on the upper part of the water-permeable stones, and then install the cylindrical organic glass sealing cavity 17 and the cover plate 18 in sequence, and make the loading rod 3 tightly contact with the pressure transmission plate 9;

[0049] Step 3, pour the saturated salt solution corresponding to the selected suction into the saturated salt solution storage container 13, open the three-way valve 14 and the exhaust valve 19 to inject the saturated salt solution into the sealed container 1 until the liquid level is slightly lower than the top surface of the cylindrical base 16, close the three-way valve 14 and the exhaust valve 19, and stand still until the saturated salt solution vapor is balanced;

[0050] Step 4, install the dial gauge 4 on the pressure transmission rod 3 and contact the dial gauge 4 with the cover plate 18, adjust the dial gauge 4 to zero, start the vertical loading device to apply load to the sample, record the dial gauge 4 reading, and apply the next level of load after the reading is stable, the level of each load is determined according to the requirements of the consolidation test in the Soil Test Procedures SL237-2019;

[0051] Step 5, after the last level of load is consolidated and stable, remove the sample to determine the moisture content, process the test results, draw the consolidation curve, and obtain the compression index, resilience index and other indicators of the soil under the condition of a certain level of suction (specific moisture content).

Claims

1. A method for determining soil wetting deformation, characterized in that, include: The ring cutter sample was placed in a sealed container (1); A constant vertical load is applied to the sample, and the saturated salt solution is dynamically replaced through a three-way valve (14) so ​​that the suction force of the sample gradually decreases from the initial value to the target value. The wet deformation of each level is continuously measured without disassembling the sample. The saturated salt solution is one or more of the following: potassium sulfate, sodium sulfate, potassium chloride, sodium chloride, potassium iodide, sodium bromide, potassium carbonate, magnesium chloride, acetic acid, lithium chloride, and lithium bromide.

2. The method according to claim 1, characterized in that, The step of placing the ring sample in a sealed container (1) specifically includes: Open the sealed container (1), place the ring cutter sample consolidation container (2) on the cylindrical base (16) in the center of the sealed container (1) and align it with the center of the cylindrical base (16); The moisture content of the soil sample was determined. Then, permeable stone (6), filter paper (7), ring sample (8), filter paper (7), and permeable stone (6) were placed in the ring sample consolidation container (2) in sequence. A pressure plate (9) was placed on top of the permeable stone. A cylindrical plexiglass sealing cavity (17) and a cover plate (18) were installed in sequence. The loading rod (3) was brought into close contact with the pressure plate (9).

3. The method according to claim 1, characterized in that, The continuous measurement of wetting deformation at various levels of the non-disassembly sample specifically includes: Install the dial indicator (4) on the pressure transmission rod (3) and make the telescopic needle of the dial indicator (4) contact the cover plate (18). Zero the pointer of the dial indicator (4), start the vertical loading device to apply a predetermined load to the sample, record the reading of the dial indicator (4), and carry out the wet deformation test after the reading stabilizes. Based on the moisture content of the sample and the soil-water characteristic curve of the sample, the initial suction force of the sample is calculated; the calculated initial suction force is compared with the suction force of various saturated salt solutions, and the saturated salt solution with a suction force value slightly lower than the calculated initial suction force is poured into the saturated salt solution storage container (13). The three-way valve (14) and the exhaust valve (19) are opened to inject the saturated salt solution into the sealed container (1) until the liquid level is slightly lower than the top surface of the cylindrical base (16). The three-way valve (14) and the exhaust valve (19) are closed, and the reading of the dial gauge (4) is recorded until the reading remains stable. Open the three-way valve (14) and the exhaust valve (19) to connect the sealed container (1) with the saturated salt solution storage container (15) and drain the saturated salt solution in the sealed container (1); then inject a saturated salt solution with a lower suction level into the sealed container (1) through the saturated salt solution storage container (13) and the three-way valve (14) until the liquid level is slightly lower than the top surface of the cylindrical base (16). Close the three-way valve (14) and the exhaust valve (19), record the reading of the dial gauge (4) until the reading remains stable, and repeat the above steps to gradually reduce the suction level until the humidification deformation is stable under the lowest suction level. Open the three-way valve (14) and the exhaust valve (19) to connect the sealed container (1) with the saturated salt solution storage container (15) and drain the saturated salt solution from the sealed container (1); then inject desaturated water into the sealed container (1) to submerge the ring cutter sample, record the reading of the dial gauge (4), and determine the wet deformation of the sample under immersion conditions.

4. An apparatus for measuring soil wetting deformation, used to implement the method according to any one of claims 1-3, characterized in that, The system includes a sealed container (1), a ring sample consolidation container (2) placed at the bottom of the sealed container, a vertical loading device, a dial gauge (4), and saturated salt solution storage devices (13) and (15); the ring sample consolidation container contains, in sequence, permeable stone (6), filter paper (7), ring sample (8), filter paper (7), permeable stone (6), and pressure plate (9); the pressure plate (9) is connected above to a vertical loading rod (3), the loading rod (3) is connected to a vertical loading device, and a dial gauge (4) is installed on the loading rod (3); the saturated salt solution storage device (13) and (15) are also included. (15) is connected to the bottom of the sealed container (1) through the plastic hose (12), and the inflow and outflow of saturated salt solution is controlled by the three-way valve (14); the test device for measuring soil wetting deformation applies vertical load to the upper part of the ring sample (8) through the pressure plate (9), and by changing different types of saturated salt solution, the suction of the soil sample is precisely controlled by the vapor balance of the saturated salt solution to make the sample wetted step by step. The same sample is used to measure the wetting deformation of the soil under different degrees of wetting, so as to realize the measurement of the wetting deformation of the soil in the high suction, i.e. low water content range. The sealed container (1) consists of a base (16) with a cylindrical protrusion at the center, a cylindrical organic glass sealed cavity (17) and a cover plate (18). The diameter of the cylindrical base (16) is the same as the diameter of the ring sample consolidation container (2), and the height is 5-10 cm. The bottom of the sealed container (1) is filled with a saturated salt solution (5), and the liquid level is slightly lower than the top surface of the cylindrical base (16). The saturated salt solution is one or more of potassium sulfate, sodium sulfate, potassium chloride, sodium chloride, potassium iodide, sodium bromide, potassium carbonate, magnesium chloride, acetic acid, lithium chloride, and lithium bromide; the suction values ​​corresponding to the above saturated salt solutions are 3.29, 12.9, 21.82, 38.0, 48.42, 71.12, 113.5, 149.51, 198.14, 286.7, and 367.54 MPa, respectively.

5. The apparatus according to claim 4, characterized in that, The bottom of the ring cutter sample consolidation container (2) and the pressure plate (9) are evenly distributed with vent holes, so that the bottom and top of the ring cutter sample can contact the saturated steam in the sealed container and achieve steam balance of the ring cutter sample.

6. The apparatus according to claim 4, characterized in that, The vertical loading device can be either lever loading or pneumatic loading.

7. The apparatus according to claim 4, characterized in that, The bottom of the sealed container (1) is connected to the saturated salt solution storage containers (13) and (15) via a plastic hose (12), and the inflow and outflow of the saturated salt solution are controlled by a three-way valve (14).

8. The apparatus according to claim 4, characterized in that, The device can gradually increase the vertical load while keeping the type of saturated salt solution constant, and measure the compression deformation characteristics of soil under a certain suction condition.

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