Unsaturated soil triaxial test system and test method

Abstract

The present invention discloses a triaxial test system and a test method for unsaturated soil, wherein a pressure chamber defines a test space; a clay plate base, a permeable stone, and a top cap are all arranged in the test space; a liquid storage container is placed on a measuring device, a first suction loading chamber is arranged on the measuring device and covers the liquid storage container, the first suction loading chamber is connected to the second suction loading chamber by a first pipeline, the second suction loading chamber is connected to the third suction loading chamber by a second pipeline, and the setting heights of the second suction loading chamber and the third suction loading chamber are both adjustable; thus, by setting the first suction loading chamber, the second suction loading chamber, and the third suction loading chamber, the suction can be accurately adjusted and controlled by adjusting the setting heights of the second suction loading chamber and the third suction loading chamber, so that precise control can be performed within a low suction range, which can improve the test accuracy, and the unsaturated soil triaxial test system proposed in the present application can perform various types of tests, which is conducive to improving the reliability of use.

Description

Technical Field

[0001] The present invention relates to the field of geotechnical engineering, and in particular to an unsaturated soil triaxial test system and a test method. Background Art

[0002] Unsaturated soil triaxial testing can simulate the stress state encountered in actual projects to test the deformation and strength characteristics of unsaturated soil. This test provides a deeper understanding of the mechanical behavior of unsaturated soil and provides an important reference for engineering design and construction. However, current unsaturated soil triaxial testing systems suffer from inaccurate control within the low suction range, resulting in low accuracy. Furthermore, current unsaturated soil triaxial testing systems are limited in functionality and can only perform one type of test, severely impacting their reliability. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide an unsaturated soil triaxial testing system that has high accuracy and is capable of performing various types of tests.

[0004] The present invention further provides a test method.

[0005] The unsaturated soil triaxial test system according to the present invention includes: a pressure chamber, which defines a test space; a top cap, a permeable stone, and a clay plate base, wherein the clay plate base, the permeable stone, and the top cap are all arranged in the test space and the clay plate base, the sample, the permeable stone, and the top cap are stacked in sequence from bottom to top; a measuring instrument, a liquid storage container, a first suction loading chamber, a second suction loading chamber, a third suction loading chamber, a first pipeline, and a second pipeline, wherein the liquid storage container is placed on the measuring instrument, the first suction loading chamber is arranged on the measuring instrument and covers the liquid storage container, and the first suction loading chamber and the second suction loading chamber are connected. The force loading chamber is connected through the first pipeline, the second suction loading chamber is connected to the third suction loading chamber through the second pipeline, and the setting heights of the second suction loading chamber and the third suction loading chamber are adjustable; the third pipeline, the fourth pipeline and the connecting pipeline, the third pipeline and the fourth pipeline are both connected between the clay plate base and the connecting pipeline, and the connecting pipeline is connected to the liquid storage container; the air pressure controller, the confining pressure controller, the fifth pipeline and the sixth pipeline, the air pressure controller is connected to the top cap through the fifth pipeline, and the confining pressure controller is connected to the test space through the sixth pipeline.

[0006] According to the unsaturated soil triaxial test system of the present invention, by setting a first suction loading chamber, a second suction loading chamber and a third suction loading chamber, the suction can be precisely adjusted and controlled by adjusting the setting heights of the second suction loading chamber and the third suction loading chamber, thereby improving the test accuracy. Moreover, the unsaturated soil triaxial test system proposed in this application can carry out various types of tests, which is conducive to improving the reliability of use.

[0007] In some examples of the present invention, the unsaturated soil triaxial testing system further includes: an axial loading rod and a force sensor, wherein the axial loading rod is used to apply an axial load to the top cap, and the force sensor is arranged between the axial loading rod and the top cap and is used to detect the loading force of the axial loading rod.

[0008] In some examples of the present invention, the unsaturated soil triaxial test system further includes: a temperature controller and a temperature sensor, the pressure chamber includes: an outer shell and an inner shell, the inner shell is arranged on the inner side of the outer shell and together with the outer shell defines a temperature cavity, the temperature controller and the temperature cavity form a heat exchange medium flow path, and the temperature sensor is arranged in the test space and is used to detect the temperature in the test space.

[0009] In some examples of the present invention, the unsaturated soil triaxial testing system also includes: a first lifting platform and a second lifting platform, the second suction loading chamber is arranged on the first lifting platform, and the third suction loading chamber is arranged on the second lifting platform, and the first lifting platform and the second lifting platform can both be raised and lowered so that the setting heights of the second suction loading chamber and the third suction loading chamber can be adjusted.

[0010] In some examples of the present invention, the top of the first suction loading chamber has a first interface, the top of the second suction loading chamber has a second interface, the first interface and the second interface are connected through the first pipeline, the bottom of the second suction loading chamber has a third interface, the bottom of the third suction loading chamber has a fourth interface, and the third interface and the fourth interface are connected through the second pipeline.

[0011] In some examples of the present invention, the unsaturated soil triaxial testing system further includes: a first pressure sensor and a second pressure sensor, the first pressure sensor being connected to the fifth pipeline and the air pressure controller, and the second pressure sensor being connected to the sixth pipeline and the confining pressure controller.

[0012] In some examples of the present invention, the unsaturated soil triaxial test system further includes: a pump, the connecting pipeline is constructed as a double U-shaped pipeline, and the pump is provided in the third pipeline or the fourth pipeline.

[0013] According to the test method of the unsaturated soil triaxial test system of the present invention, the unsaturated soil triaxial test system is the above-mentioned unsaturated soil triaxial test system, and the test method includes: applying confining pressure through the confining pressure controller; applying air pressure through the air pressure controller, adjusting the setting heights of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to perform suction balance; measuring the suction and drainage volume of the sample through the measuring instrument; obtaining the volume change of the sample according to the suction and drainage volume of the sample, and obtaining the water content, porosity and saturation of the sample according to the volume change of the sample; adjusting the setting heights of the second suction loading chamber and the third suction loading chamber multiple times to perform multiple suction balance processes, and obtaining the water content, porosity and saturation of the sample after each suction balance to obtain the soil-water characteristics of the sample.

[0014] According to the test method of the unsaturated soil triaxial test system of the present invention, the unsaturated soil triaxial test system is the above-mentioned unsaturated soil triaxial test system, and the test method includes: applying confining pressure through the confining pressure controller; applying air pressure through the air pressure controller, adjusting the setting height of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to perform suction balance; increasing the confining pressure to perform equal suction consolidation.

[0015] In some examples of the present invention, the unsaturated soil triaxial testing system also includes: an axial loading rod and a force sensor, the axial loading rod is used to apply an axial load to the top cap, the force sensor is arranged between the axial loading rod and the top cap and is used to detect the loading force of the axial loading rod, and the testing method also includes: after the suction consolidation is completed, applying force to the specimen through the axial loading rod to perform a triaxial shear test.

[0016] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0018] Figure 1 is a schematic diagram of an unsaturated soil triaxial test system according to an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of a permeable stone according to an embodiment of the present invention;

[0020] Figure 3is a flow chart of a test method of an unsaturated soil triaxial test system according to an embodiment of the present invention (soil-water property test);

[0021] Figure 4 4 is a flow chart of a test method of an unsaturated soil triaxial test system according to an embodiment of the present invention (isosuppression consolidation).

[0022] Reference numerals:

[0023] Unsaturated soil triaxial test system 100; specimen 99;

[0024] Pressure chamber 10; test space 111; outer shell 11; inner shell 12; top cap 13; permeable stone 14; clay plate base 15; measuring device 16; liquid storage container 17;

[0025] First suction loading chamber 21; first interface 211; second suction loading chamber 22; second interface 221; third interface 222; third suction loading chamber 23; fourth interface 231; first exhaust port 241; second exhaust port 242;

[0026] First pipeline 31; second pipeline 32; third pipeline 33; fourth pipeline 34; fifth pipeline 35; sixth pipeline 36; seventh pipeline 37; eighth pipeline 38;

[0027] Connecting pipeline 41; air pressure controller 42; confining pressure controller 43; axial loading rod 44; force sensor 45; pump 46;

[0028] Thermostat 51 ; temperature sensor 52 ; first lifting platform 53 ; second lifting platform 54 ; first pressure sensor 55 ; second pressure sensor 56 ; temperature chamber 57 ; heat exchange medium flow path 58 ; first communicating hole 59 ; second communicating hole 60 . DETAILED DESCRIPTION

[0029] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0030] Reference below Figure 1 An unsaturated soil triaxial testing system 100 according to an embodiment of the present invention is described.

[0031] like Figure 1As shown, the unsaturated soil triaxial testing system 100 according to an embodiment of the present invention includes: a pressure chamber 10, a top cap 13, a permeable stone 14, a clay plate base 15, a measuring device 16, a liquid storage container 17, a first suction loading chamber 21, a second suction loading chamber 22, a third suction loading chamber 23, a first pipeline 31, a second pipeline 32, a third pipeline 33, a fourth pipeline 34, a connecting pipeline 41, an air pressure controller 42, a confining pressure controller 43, a fifth pipeline 35 and a sixth pipeline 36.

[0032] The pressure chamber 10 defines a test space 111; the clay plate base 15, the permeable stone 14, and the top cap 13 are all arranged in the test space 111, and the clay plate base 15, the sample 99, the permeable stone 14, and the top cap 13 are stacked in order from bottom to top; the liquid storage container 17 is placed on the measuring device 16, the first suction loading chamber 21 is arranged on the measuring device 16 and the liquid storage container 17 is covered, the first suction loading chamber 21 is connected to the second suction loading chamber 22 through the first pipe 31, and the second suction loading chamber 22 is connected to the first suction loading chamber 21 through the second pipe 31. The loading chamber 22 is connected to the third suction loading chamber 23 via a second pipeline 32, and the heights of the second and third suction loading chambers 22, 23 are adjustable. The third and fourth pipelines 33, 34 are both connected between the clay plate base 15 and the connecting pipeline 41, and the connecting pipeline 41 is connected to the liquid storage container 17. The air pressure controller 42 is connected to the top cap 13 via a fifth pipeline 35, and the confining pressure controller 43 is connected to the test space 111 via a sixth pipeline 36.

[0033] The pressure chamber 10 defines a test space 111 for placing experimental items such as a sample 99 in the test space 111. The clay plate base 15, the permeable stone 14, and the top cap 13 are all located in the test space 111. The sample 99 is located in the test space 111. Moreover, the clay plate base 15, the sample 99, the permeable stone 14, and the top cap 13 are stacked in sequence from bottom to top along the height direction of the unsaturated soil triaxial test system 100. That is, the sample 99 is placed on the clay plate base 15, the permeable stone 14 is placed on the sample 99, and the top cap 13 is placed on the permeable stone 14.

[0034] The measurer 16 can measure weight. In some embodiments of the present application, the measurer 16 is a high-precision electronic balance.

[0035] The liquid storage container 17 is placed on the measuring device 16 to hold liquid. In some embodiments of the present application, the liquid held by the liquid storage container 17 is water. In some embodiments of the present application, the liquid storage container 17 is a beaker.

[0036] The first suction loading chamber 21 is provided in the measuring device 16 and can house the liquid storage container 17. The first suction loading chamber 21 and the measuring device 16 can form a sealed cavity. The first suction loading chamber 21 is connected to the second suction loading chamber 22 via a first pipe 31, and the second suction loading chamber 22 is connected to the third suction loading chamber 23 via a second pipe 32. In some embodiments of the present application, the first suction loading chamber 21 and the second suction loading chamber 22, and the second suction loading chamber 22 and the third suction loading chamber 23 are selectively connected.

[0037] The second suction loading chamber 22 and the third suction loading chamber 23 are both adjustable in height. That is, the second suction loading chamber 22 and the third suction loading chamber 23 are both adjustable in height. The third and fourth pipes 33 and 34 are both connected between the clay plate base 15 and the connecting pipe 41. That is, the clay plate base 15 is connected to the connecting pipe 41 via the third and fourth pipes 33 and 34. In some embodiments of the present application, the clay plate base 15 is provided with two connecting holes, and the third and fourth pipes 33 and 34 are respectively connected to the two connecting holes of the clay plate base 15, and both the third and fourth pipes 33 and 34 are connected to the connecting pipe. The connecting pipe 41 is connected to the liquid storage container 17. In some embodiments of the present application, the connecting pipe 41 is constructed as a double U-shaped water outlet pipe.

[0038] The air pressure controller 42 is connected to the top cap 13 through the fifth pipeline 35 to provide gas pressure above the sample 99. As some embodiments of the present application, the air pressure controller 42 can be connected to the gas source to control the pressure of the gas flowing out of the gas source.

[0039] The confining pressure controller 43 is connected to the test space 111 through the sixth pipeline 36 to provide pressure around the sample 99. As some embodiments of the present application, the confining pressure controller 43 can be connected to an air source or a water source to control the pressure of the fluid flowing out of the air source or the water source to apply pressure to the test space 111.

[0040] As some embodiments of the present application, the pressure chamber 10 is disposed on a reaction support.

[0041] As some embodiments of the present application, the soil-water properties of the sample 99 can be tested by the unsaturated soil triaxial test system 100 proposed in the present application, the equal suction consolidation test can be performed by the unsaturated soil triaxial test system 100 proposed in the present application, and the triaxial shear test can be performed by the unsaturated soil triaxial test system 100 proposed in the present application.

[0042] The clay plate base 15 can be saturated in advance, and the liquid storage container 17 can be filled with water so that the water level does not exceed the connecting pipe 41. The exhaust port of the first suction loading chamber 21 is closed, and the second suction loading chamber 22 and the third suction loading chamber 23 are filled with water to about 2 / 3 of their capacity in advance. The second exhaust port 242 of the third suction loading chamber 23 is closed, and the pipeline valve between the second suction loading chamber 22 and the third suction loading chamber 23 is closed, so that the second pipeline 32 between the second suction loading chamber 22 and the third suction loading chamber 23 is disconnected (not conductive). The air inside all pipes of the unsaturated soil triaxial test system 100 is removed, and the clay plate base 15, the specimen 99, the permeable stone 14, and the top cap 13 are stacked in order from bottom to top along the height direction of the unsaturated soil triaxial test system 100. The pressure chamber 10 is filled with water, and the confining pressure is applied by the confining pressure controller 43 and the air pressure is applied by the air pressure controller 42. The setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 are adjusted to control the height difference between the second suction loading chamber 22 and the third suction loading chamber 23, so as to achieve suction balance.

[0043] After the suction balance is performed, if it is necessary to obtain the soil and water characteristics of the sample 99, the suction and drainage volume of the sample 99 is measured by the measuring device 16; the volume change of the sample 99 is obtained according to the suction and drainage volume of the sample 99, and the water content, porosity and saturation of the sample 99 are obtained according to the volume change of the sample 99; the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 are adjusted multiple times to perform multiple suction balance processes, and after each suction balance, the water content, porosity and saturation of the sample 99 are obtained to obtain the soil and water characteristics of the sample 99.

[0044] After the suction balance is achieved, isotropic consolidation can be performed by increasing the confining pressure.

[0045] After suction balance is performed, if a triaxial shear test is required, the confining pressure can be increased first to perform constant suction consolidation, and then a force is applied to the specimen 99 through the axial loading rod 44 to perform the triaxial shear test.

[0046] It should be noted that the unsaturated soil triaxial testing system 100 of the present application can precisely adjust and control suction by adjusting the height of the second suction loading chamber 22 and the third suction loading chamber 23, thereby enabling precise control within a low suction range. Furthermore, the unsaturated soil triaxial testing system 100 proposed in the present application can perform, but is not limited to, soil-water property tests, constant suction consolidation tests, and triaxial shear tests.

[0047] Therefore, by setting the first suction loading chamber 21, the second suction loading chamber 22 and the third suction loading chamber 23, the suction can be precisely adjusted and controlled by adjusting the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23, thereby improving the test accuracy. Moreover, the unsaturated soil triaxial test system 100 proposed in this application can carry out various types of tests, which is conducive to improving the reliability of use.

[0048] In some embodiments of the present invention, Figure 1 As shown, the unsaturated soil triaxial test system 100 also includes: an axial loading rod 44 and a force sensor 45. The axial loading rod 44 is used to apply an axial load to the top cap 13. The force sensor 45 is arranged between the axial loading rod 44 and the top cap 13 and is used to detect the loading force of the axial loading rod 44.

[0049] The unsaturated soil triaxial test system 100 further includes an axial loading rod 44 and a force sensor 45. The axial loading rod 44 is used to apply an axial load to the top cap 13, thereby applying an axial load to the specimen 99 through the top cap 13. The force sensor 45 is disposed between the axial loading rod 44 and the top cap 13, and the force sensor 45 is capable of detecting the loading force of the axial loading rod 44. It will be understood that by applying an axial load to the specimen 99 through the axial loading rod 44, a triaxial shear test can be performed.

[0050] By making the unsaturated soil triaxial test system 100 also include an axial loading rod 44 and a force sensor 45, it is possible to facilitate the application of axial load to the specimen 99 to test the specimen 99. In addition, such an arrangement can facilitate the detection of the loading force of the axial loading rod 44, has a simple structure, and is conducive to the reliability of the unsaturated soil triaxial test system 100.

[0051] In some embodiments of the present invention, Figure 1 As shown, the unsaturated soil triaxial test system 100 further includes: a temperature controller 51 and a temperature sensor 52. The pressure chamber 10 includes: an outer shell 11 and an inner shell 12. The inner shell 12 is arranged on the inner side of the outer shell 11 and defines a temperature chamber 57 together with the outer shell 11. The temperature controller 51 and the temperature chamber 57 form a heat exchange medium flow path 58. The temperature sensor 52 is arranged in the test space 111 and is used to detect the temperature in the test space 111.

[0052] Among them, the unsaturated soil triaxial test system 100 also includes a temperature controller 51 and a temperature sensor 52, the pressure chamber 10 includes an outer shell 11 and an inner shell 12, the inner shell 12 is arranged on the inner side of the outer shell 11, and the inner shell 12 and the outer shell 11 jointly define a temperature chamber 57, the temperature controller 51 and the temperature chamber 57 form a heat exchange medium flow path 58, the temperature sensor 52 is arranged in the test space 111, and the temperature sensor 52 is used to detect the temperature in the test space 111. As some embodiments of the present application, the temperature sensor 52 is electrically connected to the temperature controller 51, and the temperature sensor 52 can detect the temperature in the test space 111 and feed the temperature back to the temperature controller 51. The temperature controller 51 can adjust the temperature of the temperature chamber 57 according to the temperature information fed back by the temperature sensor 52. As some embodiments of the present application, the heat exchange medium can be water.

[0053] By making the unsaturated soil triaxial test system 100 also include a temperature controller 51 and a temperature sensor 52, it is possible to facilitate the adjustment of the temperature of the test space 111, facilitate the detection of the sample 99 at different temperatures, and also facilitate the maintenance of a constant temperature during the test, which is beneficial to the accuracy of the test.

[0054] As some embodiments of the present application, the unsaturated soil triaxial test system 100 also includes: a seventh pipeline 37 and an eighth pipeline 38, the shell 11 has a first connecting hole 59 and a second connecting hole 60, the seventh pipeline 37 is connected between the first connecting hole 59 and the temperature controller 51, and the eighth pipeline 38 is connected between the second connecting hole 60 and the temperature controller 51. The temperature controller 51, the seventh pipeline 37, the temperature chamber 57, and the eighth pipeline 38 form a heat exchange medium flow path 58.

[0055] In some embodiments of the present invention, Figure 1 As shown, the unsaturated soil triaxial test system 100 also includes: a first lifting platform 53 and a second lifting platform 54, the second suction loading chamber 22 is arranged on the first lifting platform 53, and the third suction loading chamber 23 is arranged on the second lifting platform 54, and the first lifting platform 53 and the second lifting platform 54 can both be raised and lowered so that the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 can be adjusted.

[0056] Among them, the unsaturated soil triaxial test system 100 also includes a first lifting platform 53 and a second lifting platform 54. The second suction loading chamber 22 is arranged on the first lifting platform 53, and the third suction loading chamber 23 is arranged on the second lifting platform 54. The first lifting platform 53 and the second lifting platform 54 can both be raised and lowered so that the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 can be adjusted. As some embodiments of the present application, the first lifting platform 53 and the second lifting platform 54 can be driven respectively by two driving members so that the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 can be adjusted.

[0057] By making the unsaturated soil triaxial test system 100 also include a first lifting platform 53 and a second lifting platform 54, the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 can be adjusted, and the setting heights of the second suction loading chamber 22 and the third suction loading chamber 23 can be easily adjusted, so that the suction can be accurately adjusted and controlled, and precise control can be performed within a low suction range, which is conducive to improving the accuracy of the test.

[0058] In some embodiments of the present invention, Figure 1 As shown, the top of the first suction loading chamber 21 has a first interface 211, the top of the second suction loading chamber 22 has a second interface 221, the first interface 211 and the second interface 221 are connected through a first pipeline 31, the bottom of the second suction loading chamber 22 has a third interface 222, the bottom of the third suction loading chamber 23 has a fourth interface 231, and the third interface 222 and the fourth interface 231 are connected through a second pipeline 32.

[0059] Among them, the top of the first suction loading chamber 21 has a first interface 211, and the top of the second suction loading chamber 22 has a second interface 221. The first interface 211 and the second interface 221 are connected through a first pipeline 31, so that the first suction loading chamber 21 and the second suction loading chamber 22 are connected through the first pipeline 31.

[0060] The bottom of the second suction loading chamber 22 has a third interface 222, and the bottom of the third suction loading chamber 23 has a fourth interface 231. The third interface 222 and the fourth interface 231 are connected through the second pipeline 32, so that the third suction loading chamber 23 and the fourth suction loading chamber are connected through the second pipeline 32.

[0061] As some embodiments of the present application, the top of the second suction loading chamber 22 has a first exhaust port 241, which is connected to the outside world, and the top of the third suction loading chamber 23 has a second exhaust port 242, which is connected to the outside world.

[0062] Such an arrangement enables reasonable connection among the first suction loading chamber 21 , the second suction loading chamber 22 and the third suction loading chamber 23 , facilitates precise control within a low suction range through the first suction loading chamber 21 , the second suction loading chamber 22 and the third suction loading chamber 23 , and can improve test accuracy.

[0063] In some embodiments of the present invention, Figure 1As shown, the unsaturated soil triaxial test system 100 further includes: a first pressure sensor 55 and a second pressure sensor 56 . The first pressure sensor 55 is connected to the fifth pipeline 35 and the air pressure controller 42 , and the second pressure sensor 56 is connected to the sixth pipeline 36 and the confining pressure controller 43 .

[0064] Among them, the unsaturated soil triaxial test system 100 also includes a first pressure sensor 55 and a second pressure sensor 56. The first pressure sensor 55 is connected to the fifth pipeline 35 and the air pressure controller 42. The first pressure sensor 55 can detect the pressure information in the fifth pipeline 35 and feed back the pressure information in the fifth pipeline 35 to the air pressure controller 42.

[0065] The second pressure sensor 56 is connected to both the sixth pipeline 36 and the confining pressure controller 43 . The second pressure sensor 56 can detect pressure information in the sixth pipeline 36 and feed the pressure information in the sixth pipeline 36 back to the confining pressure controller 43 .

[0066] As some embodiments of the present application, the first pressure sensor 55 and the second pressure sensor 56 can also display volume readings.

[0067] By making the unsaturated soil triaxial test system 100 also include a first pressure sensor 55 and a second pressure sensor 56, the detected pressure information can be fed back to the air pressure controller 42 through the first pressure sensor 55, and the detected pressure information can be fed back to the confining pressure controller 43 through the second pressure sensor 56, so that the air pressure controller 42 can accurately control the air pressure, and the confining pressure controller 43 can accurately control the confining pressure, thereby improving the test accuracy of the unsaturated soil triaxial test system 100.

[0068] In some embodiments of the present invention, Figure 1 As shown, the unsaturated soil triaxial test system 100 further includes a pump 46 . The connecting pipeline 41 is constructed as a double U-shaped pipeline. The pump 46 is provided in the third pipeline 33 or the fourth pipeline 34 .

[0069] Among them, the unsaturated soil triaxial test system 100 also includes a pump 46, and the connecting pipeline 41 is constructed as a double U-shaped pipeline, wherein one U-shaped pipeline is connected to the third pipeline 33, and the other U-shaped pipeline is connected to the fourth pipeline 34. The pump 46 is arranged in the third pipeline 33 or the fourth pipeline 34, that is, the pump 46 is arranged in the third pipeline 33, or the pump 46 is arranged in the fourth pipeline 34.

[0070] As some embodiments of the present application, the pump member 46 may be configured as a peristaltic pump.

[0071] By making the unsaturated soil triaxial test system 100 further include the pump member 46 , the unsaturated soil triaxial test system 100 can flush out the bubbles at the bottom of the clay plate base 15 through the pump member 46 , which is beneficial to improving the test accuracy of the unsaturated soil triaxial test system 100 .

[0072] Refer to the following Figure 3 The present invention introduces a test method for an unsaturated soil triaxial test system, wherein the unsaturated soil triaxial test system is the unsaturated soil triaxial test system described above. The test method includes the following steps:

[0073] S1, applying confining pressure through the confining pressure controller;

[0074] The confining pressure is applied by a confining pressure controller, that is, the confining pressure is applied to the sample in the test space by the confining pressure controller.

[0075] S2, applying air pressure through an air pressure controller to adjust the setting heights of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to achieve suction balance;

[0076] Among them, air pressure is applied to the top cap above the sample in the test space through an air pressure controller, and by adjusting the heights of the first lifting platform and the second lifting platform, the setting heights of the second suction loading chamber and the third suction loading chamber can be adjusted to control the height difference between the second suction loading chamber and the third suction loading chamber for suction balance.

[0077] S3, measuring the amount of water absorbed and discharged by the sample through a measuring device; it can be understood that if the sample absorbs water, the liquid in the liquid storage container will decrease, and if the sample discharges water, the liquid in the liquid storage container will increase. By measuring the weight of the liquid in the liquid storage container that decreases or increases through a measuring device, the amount of water absorbed and discharged by the sample can be obtained.

[0078] S4, obtaining a volume change of the sample according to the amount of water absorbed and discharged by the sample, and obtaining a water content, a porosity, and a saturation degree of the sample according to the volume change of the sample;

[0079] That is to say, the volume change of the sample can be obtained according to the amount of water absorbed and discharged by the sample, and further the water content, porosity and saturation of the sample can be obtained according to the volume change of the sample.

[0080] S5, adjust the setting heights of the second suction loading chamber and the third suction loading chamber multiple times to perform multiple suction balance processes, and after each suction balance, obtain the moisture content, porosity and saturation of the sample to obtain the soil and water characteristics of the sample.

[0081] Among them, by adjusting the setting heights of the second suction loading chamber and the third suction loading chamber multiple times, the height difference between the second suction loading chamber 22 and the third suction loading chamber 23 is controlled multiple times, and by adjusting the air pressure controller multiple times to match the different height differences between the second suction loading chamber and the third suction loading chamber, multiple suction balance processes are performed, and after each suction balance, the moisture content, porosity and saturation of the sample are obtained to obtain the soil-water characteristics of the unsaturated soil sample.

[0082] As some embodiments of the present application, before applying confining pressure through the confining pressure controller, the base of the clay plate is saturated in advance, and water is filled into the liquid storage container so that the water level does not exceed the connecting pipeline, the exhaust port of the first suction loading chamber is closed, and the second suction loading chamber and the third suction loading chamber are filled with about 2 / 3 of the capacity of water in advance, the second exhaust port of the third suction loading chamber is closed, and the pipeline valve between the second suction loading chamber and the third suction loading chamber is closed to disconnect the second pipeline between the second suction loading chamber and the third suction loading chamber (not conducting).

[0083] Expel the air from all pipes of the unsaturated soil triaxial test system and open the pump to flush out the air bubbles in the cavity at the bottom of the clay plate base.

[0084] Place the prepared sample on the clay plate base and fix it to the sample through a top cap embedded with permeable stone. Fill the pressure chamber with water, tighten the sealing bolts of the pressure chamber, and reset the readings of the first pressure sensor and the second pressure sensor to zero.

[0085] Finally, turn on the thermostat and adjust the pressure chamber to the temperature required for the test. After the reading of the built-in temperature sensor in the pressure chamber stabilizes, apply confining pressure through the confining pressure controller to carry out the test.

[0086] Therefore, the soil-water characteristics of the sample can be accurately obtained through the test method of the unsaturated soil triaxial test system of the present application.

[0087] Refer to the following Figure 4 The test method of the unsaturated soil triaxial test system of the present invention is introduced. The unsaturated soil triaxial test system is the unsaturated soil triaxial test system mentioned above. The test method includes:

[0088] S01, applying confining pressure through the confining pressure controller;

[0089] The confining pressure is applied by a confining pressure controller, that is, the confining pressure is applied to the sample in the test space by the confining pressure controller.

[0090] S02, applying air pressure through an air pressure controller to adjust the setting heights of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to achieve suction balance;

[0091] Among them, air pressure is applied to the top cap above the sample in the test space through an air pressure controller, and by adjusting the heights of the first lifting platform and the second lifting platform, the setting heights of the second suction loading chamber and the third suction loading chamber can be adjusted to control the height difference between the second suction loading chamber and the third suction loading chamber for suction balance.

[0092] S03, increase the confining pressure and perform isotropic consolidation.

[0093] The confining pressure can be increased by a confining pressure controller to perform isotropic consolidation. In some embodiments of the present application, the reading of the second pressure sensor indicates that the isotropic consolidation is completed.

[0094] As some embodiments of the present application, before applying confining pressure through the confining pressure controller, the base of the clay plate is saturated in advance, and water is filled into the liquid storage container so that the water level does not exceed the connecting pipeline, the exhaust port of the first suction loading chamber is closed, and the second suction loading chamber and the third suction loading chamber are filled with about 2 / 3 of the capacity of water in advance, the second exhaust port of the third suction loading chamber is closed, and the pipeline valve between the second suction loading chamber and the third suction loading chamber is closed to disconnect the second pipeline between the second suction loading chamber and the third suction loading chamber (not conducting).

[0095] Expel the air from all pipes of the unsaturated soil triaxial test system and open the pump to flush out the air bubbles in the cavity at the bottom of the clay plate base.

[0096] Place the prepared sample on the clay plate base and fix it to the sample through a top cap embedded with permeable stone. Fill the pressure chamber with water, tighten the sealing bolts of the pressure chamber, and reset the readings of the first pressure sensor and the second pressure sensor to zero.

[0097] Finally, turn on the thermostat and adjust the pressure chamber to the temperature required for the test. After the reading of the built-in temperature sensor in the pressure chamber stabilizes, apply confining pressure through the confining pressure controller to carry out the test.

[0098] Therefore, through the test method of the unsaturated soil triaxial test system of the present application, isotropic consolidation can be performed accurately, stably and reliably.

[0099] In some embodiments of the present invention, the unsaturated soil triaxial testing system further includes: an axial loading rod and a force sensor, wherein the axial loading rod is used to apply an axial load to the top cap, and the force sensor is arranged between the axial loading rod and the top cap and is used to detect the loading force of the axial loading rod.

[0100] Among them, the unsaturated soil triaxial test system also includes an axial loading rod and a force sensor. The axial loading rod is used to apply an axial load to the top cap so as to apply an axial load to the specimen through the top cap. The force sensor is arranged between the axial loading rod and the top cap, and the force sensor can detect the loading force of the axial loading rod.

[0101] The test method of the unsaturated soil triaxial test system also includes: after the suction consolidation is completed, a force is applied to the specimen through an axial loading rod to perform a triaxial shear test.

[0102] Therefore, the triaxial shear test can be accurately performed through the unsaturated soil triaxial test system proposed in this application.

[0103] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0104] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0105] In the description of the present invention, "plurality" means two or more.

[0106] In the description of the present invention, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact with each other, or the first and second features not being in direct contact with each other but being in contact with each other via another feature therebetween.

[0107] In the description of the present invention, “on”, “above” and “above” a first feature of a second feature include the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0108] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0109] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. An unsaturated soil triaxial test system, characterized in that: It includes a pressure chamber, a top cap, a permeable stone, a clay plate base, a measuring device, a liquid storage container, a first suction loading chamber, a second suction loading chamber, a third suction loading chamber, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a connecting pipeline, an air pressure controller, a confining pressure controller, a fifth pipeline, and a sixth pipeline; The pressure chamber defines a test space, the clay plate base, the permeable stone, and the top cap are all arranged in the test space, and the clay plate base, the sample, the permeable stone, and the top cap are stacked in sequence from bottom to top, the liquid storage container is placed on the measuring instrument, the first suction loading chamber is arranged on the measuring instrument and covers the liquid storage container, the first suction loading chamber is connected to the second suction loading chamber through the first pipeline, the second suction loading chamber is connected to the third suction loading chamber through the second pipeline, the setting heights of the second suction loading chamber and the third suction loading chamber are adjustable, the third pipeline and the fourth The pipelines are all connected between the clay plate base and the connecting pipeline, and the connecting pipeline is connected to the liquid storage container, the air pressure controller is connected to the top cap through the fifth pipeline, and the confining pressure controller is connected to the test space through the sixth pipeline. The top of the first suction loading chamber has a first interface, the top of the second suction loading chamber has a second interface, the first interface and the second interface are connected through the first pipeline, the bottom of the second suction loading chamber has a third interface, the bottom of the third suction loading chamber has a fourth interface, and the third interface and the fourth interface are connected through the second pipeline.

2. The unsaturated soil triaxial testing system according to claim 1, characterized in that: The unsaturated soil triaxial test system also includes: an axial loading rod and a force sensor, wherein the axial loading rod is used to apply an axial load to the top cap, and the force sensor is arranged between the axial loading rod and the top cap and is used to detect the loading force of the axial loading rod.

3. The unsaturated soil triaxial testing system according to claim 1, characterized in that: The unsaturated soil triaxial test system also includes: a temperature controller and a temperature sensor. The pressure chamber includes: an outer shell and an inner shell. The inner shell is arranged on the inner side of the outer shell and together with the outer shell defines a temperature chamber. The temperature controller and the temperature chamber form a heat exchange medium flow path. The temperature sensor is arranged in the test space and is used to detect the temperature in the test space.

4. The unsaturated soil triaxial testing system according to claim 1, characterized in that: The unsaturated soil triaxial test system also includes: a first lifting platform and a second lifting platform, the second suction loading chamber is arranged on the first lifting platform, and the third suction loading chamber is arranged on the second lifting platform, and the first lifting platform and the second lifting platform can both be raised and lowered so that the setting heights of the second suction loading chamber and the third suction loading chamber can be adjusted.

5. The unsaturated soil triaxial testing system according to claim 1, characterized in that: The unsaturated soil triaxial test system further includes: a first pressure sensor and a second pressure sensor, wherein the first pressure sensor is connected to both the fifth pipeline and the air pressure controller, and the second pressure sensor is connected to both the sixth pipeline and the confining pressure controller.

6. The unsaturated soil triaxial testing system according to claim 1, characterized in that: The unsaturated soil triaxial test system further includes a pump component. The connecting pipeline is constructed as a double U-shaped pipeline. The pump component is provided in the third pipeline or the fourth pipeline.

7. A test method for an unsaturated soil triaxial test system, characterized in that: The unsaturated soil triaxial test system is an unsaturated soil triaxial test system according to any one of claims 1 to 6, and the test method includes: applying confining pressure via the confining pressure controller; Applying air pressure through the air pressure controller to adjust the setting heights of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to achieve suction balance; measuring the amount of water absorbed and discharged by the sample by the measuring device; Obtaining a volume change of the sample according to the amount of water absorbed and discharged by the sample, and obtaining a water content, a porosity ratio, and a saturation degree of the sample according to the volume change of the sample; The setting heights of the second suction loading chamber and the third suction loading chamber are adjusted multiple times to perform multiple suction balancing processes, and after each suction balancing, the moisture content, porosity and saturation of the sample are obtained to obtain the soil and water properties of the sample.

8. A test method for an unsaturated soil triaxial test system, characterized in that: The unsaturated soil triaxial test system is an unsaturated soil triaxial test system according to any one of claims 1 to 6, and the test method includes: applying confining pressure via the confining pressure controller; Applying air pressure through the air pressure controller to adjust the setting heights of the second suction loading chamber and the third suction loading chamber to control the height difference between the second suction loading chamber and the third suction loading chamber to achieve suction balance; Increase the confining pressure and carry out isotropic consolidation.

9. The test method of the unsaturated soil triaxial test system according to claim 8, characterized in that: The unsaturated soil triaxial test system further includes: an axial loading rod and a force sensor, wherein the axial loading rod is used to apply an axial load to the top cap, and the force sensor is provided between the axial loading rod and the top cap and is used to detect the loading force of the axial loading rod. The test method further includes: After the suction consolidation is completed, a force is applied to the specimen through the axial loading rod to perform a triaxial shear test.

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