A tester for the mechanical properties of soil under wet-dry or freeze-thaw cycles.

Abstract

A mechanical property testing instrument for soil under wet-dry or freeze-thaw cycles includes a test frame, a container, a water tank assembly, an upper loading component, a lower loading component, a circumferential loading component, a shear component, a displacement detection component, and a control device. The test frame is equipped with a base plate and several grooves. The bottom of the container is detachably sealed to the base plate. The water tank assembly is used to inject solution. The upper loading component compacts the sample in the container or applies axial loading. The lower loading component adjusts the axial position of the sample. The circumferential loading component applies radial pressure to the sample. The shear component shears and destroys the sample. The displacement detection component is mounted on the upper loading component, the circumferential loading component, and the shear component. The control device is connected to the upper loading component, the lower loading component, the circumferential loading component, the shear component, and the displacement detection component. This invention enables continuous testing of mechanical properties of a single sample and a single device without removing the sample, greatly simplifying the corresponding operation steps and equipment.

Description

Technical Field

[0001] This invention relates to the field of soil performance testing, and in particular to a tester for the mechanical properties of soil under wet-dry or freeze-thaw cycles. Background Technology

[0002] Environmental issues have a particularly significant impact on soil properties. In particular, the effects of various factors such as seasonal changes, surface runoff, rise or fall of groundwater levels, and diurnal temperature variations on soil properties, including the effects of wet-dry or freeze-thaw cycles, are worth studying. These cycles can degrade the mechanical properties of materials, leading to dangerous engineering situations such as slope instability, foundation pit collapse, soil liquefaction, and sudden drop in strength.

[0003] Currently, most experimental setups for testing the mechanical properties of geotechnical materials are designed for single-property testing, and these devices are large in size and expensive. They cannot achieve rapid testing of multiple mechanical properties in a unified manner. Furthermore, these methods are cumbersome and prone to disturbing the sample during the experiment, affecting measurement accuracy. Therefore, it is necessary to develop a new type of mechanical property testing equipment for soil to solve the above problems. Summary of the Invention

[0004] The main objective of this invention is to overcome the aforementioned deficiencies in the prior art and to propose a soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects, which can detect a variety of soil properties.

[0005] The present invention adopts the following technical solution:

[0006] A mechanical property testing instrument for soil under wet-dry or freeze-thaw cycle effects, characterized in that it includes a testing frame, a container, a water tank assembly, an upper loading component, a lower loading component, a circumferential loading component, a shear component, a displacement detection component, and a control device; the testing frame is provided with an experimental operation area, the bottom surface of which is provided with a movable base plate and several chutes, the chutes being located on the outer periphery of the base plate and extending along a first or second direction; the container is vertically continuous and its bottom is detachably sealed to the base plate for placing a sample; the water tank assembly is slidably fitted with the chutes and is provided with several water cavities surrounding the outer periphery of the container for injecting solution, the water cavities being communicative with the container; the upper loading component is vertically and vertically mounted on the test frame. The top of the container is used to compact or axially load the sample inside the container; the lower loading assembly is detachably connected to the bottom plate and can be raised and lowered to adjust the axial position of the sample; the circumferential loading assembly is movably inserted through the water tank assembly and can apply radial pressure to the sample; the shearing assembly is movably inserted through the water tank assembly and can shear and destroy the sample; the displacement detection assembly includes several displacement sensors, which are respectively disposed on the upper loading assembly, the circumferential loading assembly, and the shearing assembly to detect displacement information; the control device is connected to the upper loading assembly, the lower loading assembly, the circumferential loading assembly, the shearing assembly, and the displacement detection assembly.

[0007] The container includes two shells; the two shells are symmetrically arranged and detachably connected, the bottom of the shell is sealed to the base plate, and the sides of the shell are provided with a plurality of communicating holes and a plurality of connecting pieces; the test frame is provided with two retractable pull rod groups, and the two pull rod groups are detachably connected to the connecting pieces on the two shells; the control device is connected to the pull rod groups to control their movement to drive the two sleeves to move along the slide groove to achieve disassembly and assembly.

[0008] The container has several detachable first fixing pieces and several detachable second fixing pieces on its side. The several first fixing pieces are spaced apart along a first direction or a second direction of the test frame. The several second fixing pieces are spaced apart along the diagonal of the side of the container.

[0009] It also includes several sealing layers, which can be inserted axially into the inside of the water cavity to seal the connecting hole so as to facilitate non-drain shearing. A breathable and water-permeable layer can also be provided between the sealing layer and the inner wall of the water cavity; or the container is also provided with a filling layer, which fills the gap between the sample and the inside of the water cavity to control the shape of the sample.

[0010] The water tank assembly includes multiple water tanks, which are located on different sides of the container and slide in conjunction with the chute. Each water tank contains a water cavity, and each water tank has a removable cover plate on its top. An axially movable inner side plate is provided on the side of each water tank opposite to the container, and the inner side plate has the communicating hole. A drain hole and a vent hole are also provided on the side of each water tank opposite to the inner side plate. At least one water tank has a water injection hole and a temperature sensor on its cover plate, and the water injection hole has a removable sealing plug.

[0011] The base plate has a through slot in the middle, and the slot is equipped with a removable sealing sleeve; it also includes a number of support rods, one end of which is detachably connected to the base plate, and the other end is detachably connected to the test frame to support the base plate when it is raised to the design height.

[0012] The upper loading assembly includes an upper pressure plate, an upper telescopic rod, and an upper driving component. The upper pressure plate is located above the container and has an opening with a removable cover. A removable probe is also provided on the upper pressure plate to insert into the sample to detect moisture content or humidity. The upper telescopic rod passes through the upper pressure plate and has an upper drill bit at its end, which is located inside the opening of the upper pressure plate. The upper driving component connects and drives the upper pressure plate and the upper telescopic rod to rise or fall, and a displacement sensor is provided on the upper driving component.

[0013] The lower loading assembly includes a lower pressure plate, a lower telescopic rod, and a lower drive component; the lower pressure plate is detachably connected to the base plate and has an opening, with a detachable cover at the opening; the lower telescopic rod passes through the lower pressure plate and has a lower drill bit at its end, the lower drill bit being located within the opening of the lower pressure plate; the lower drive component connects and drives the lower pressure plate and the lower telescopic rod to rise or fall, and the lower drive component is equipped with the displacement sensor.

[0014] The circumferential loading assembly includes several side pressure plates and several side drive components. The several side pressure plates are respectively located in different water chambers of the water tank assembly. The several side drive components are respectively connected to drive the corresponding side pressure plates to move. The displacement sensor is provided on the side drive component.

[0015] The shearing assembly includes several shearing plates and several shearing drive components. The shearing plates are located in different water chambers of the water tank assembly, and the shearing drive components are respectively connected to drive the corresponding shearing plates to move. Several displacement sensors are provided on the shearing drive components.

[0016] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0017] This invention provides a mechanical property testing instrument for soil under dry-wet or freeze-thaw cycle effects, including a test frame, container, water tank assembly, upper loading component, lower loading component, circumferential loading component, shear component, displacement detection component, and control device. It realizes the function of continuously testing mechanical properties (compression resistance, crack resistance, and shear resistance) with a single sample and a single device without removing the sample, which greatly simplifies the corresponding operation steps and equipment, and eliminates the influence of sample loss caused by human factors or improper operation on the test results.

[0018] The testing instrument of this invention can be divided into two parts: the first part is the sample preparation part, and the second part is the core testing part of the device. Before the sample is formally loaded into the testing instrument, the mass of the sample needs to be controlled according to the optimal moisture content and maximum dry density obtained from the compaction test. A stainless steel container is fixed to the upper part of the lower pressure plate, and the sample is added into it. The upper pressure plate is moved down to the sample surface by computer-controlled hydraulic rods to hydraulically form the sample and hold it for 1-2 hours. The upper pressure plate is moved away as needed; and the annular water tank is moved around the stainless steel container as needed to saturate, wet-dry, or freeze-thaw the sample. Then, the relevant mechanical properties of the sample are tested by computer-controlled hydraulic rods.

[0019] This invention can be applied to compressive strength tests (unconfined or confined), crack strength tests (inducing crack development), conventional shear strength tests (drained or undrained), and oblique shear tests. Furthermore, consolidation tests can be performed using this instrument. Simultaneously, it can simulate wet-dry or freeze-thaw cycles during experiments, and can simulate the effects of different salt ions and varying solution pH values ​​in the natural environment on the mechanical properties of materials.

[0020] This device also has other testing functions, as follows:

[0021] (a) Mechanical property testing of materials under the coupled action of dry-wet-freeze-thaw cycles: Based on the basic process of a single dry-wet or freeze-thaw cycle, the relevant mechanical properties are tested after multiple cycles as needed.

[0022] (b) Depending on the experimental requirements, the experiment can control whether there is an overlying load to perform wet-dry or freeze-thaw cycles and to test the mechanical properties after solidification of different solutions. The force loading range in the experiment is between 0 and 3.0 MPa (which needs to be determined based on the pressure (push) in the experiment and the specific material of the experimental device). Attached Figure Description

[0023] Figure 1 This is an overall diagram of the device of the present invention;

[0024] Figure 2 This is a top view of the present invention;

[0025] Figure 3 Diagram showing the assembly of the water tank assembly and its various loading components;

[0026] Figure 4 Diagram showing the assembly of the water tank assembly with each loading component (displacement sensor);

[0027] Figure 5 This is a schematic diagram of a single water tank;

[0028] Figure 6 A schematic diagram showing the positions of each loading component and the sample;

[0029] Figure 7 For use with a single water tank and loading components Figure 1 ;

[0030] Figure 8 For use with a single water tank and loading components Figure 2 ;

[0031] Figure 9 This is a diagram of the container structure.

[0032] Figure 10 This is a side view of the container;

[0033] Figure 11 This is a structural diagram of the base plate;

[0034] Figure 12 Diagram showing the fit between the bottom of the water tank and the sliding groove;

[0035] Figure 13 Diagram showing the mating of the first fixing piece and the container;

[0036] Figure 14 This is a schematic diagram of the failure of a specimen in a crack strength test.

[0037] The components are as follows: 10. Test frame; 11. Iron support; 12. Experimental operation area; 13. Base plate; 14. Slide groove; 15. Tie rod assembly; 16. Groove; 17. Sealing sleeve; 18. Support rod; 19. Connecting hole; 20. Container; 20a. Bolt; 21. Shell; 22. Fixing plate; 23. Connecting hole; 24. Connecting plate; 25. First fixing plate; 26. Second fixing plate; 27. Positive shear surface; 28. Oblique shear surface; 29. ​​Filling layer; 30. Water tank assembly; 31. Water tank; 32. Inner side plate; 33. Sealing layer; 34. Breathable and water-permeable layer; 35. Water cavity; 36. 37. Cover plate; 38. Drain hole; 39. Vent hole; 40. Water injection hole; 41. Upper loading assembly; 42. Upper pressure plate; 43. Upper telescopic rod; 44. Upper drive component; 45. Opening; 46. Cover body; 47. Upper drill bit; 48. Probe; 49. Dial indicator; 50. Rubber sleeve; 51. Lower loading assembly; 52. Lower pressure plate; 53. Lower telescopic rod; 54. Lower drive component; 60. Circumferential loading assembly; 61. Side pressure plate; 62. Side drive component; 70. Shearing assembly; 71. Shearing plate; 72. Shearing drive component; 81. Displacement sensor; 82. Temperature sensor.

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0039] The present invention will be further described below through specific embodiments.

[0040] In this invention, the terms "first," "second," and "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. The use of terms such as "upper," "lower," "left," "right," "front," and "rear" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention, not to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the scope of protection of this invention. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0042] See Figures 1 to 13A soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects includes a test frame 10, a container 20, a water tank assembly 30, an upper loading component 40, a lower loading component 50, a circumferential loading component 60, a shear component 70, a displacement detection component, and a control device. The test frame 10 includes several iron supports 11 connected together to form an experimental operation area 12. The experimental operation area 12 is used for various testing experiments. The bottom iron supports 11 of the experimental operation area 12 are provided with a movable base plate 13 and several sliding grooves 14. The bottom iron supports 11 have clearance openings to allow space for the base plate 13. The sliding grooves 14 are located on the bottom iron supports 11 and extend along a first or second direction around the clearance opening. The first and second directions are perpendicular; that is, some sliding grooves 14 extend along the first direction, and some extend along the second direction. The specific number is not limited and is set according to actual needs.

[0043] The container 20 of this invention is the core container for the sample. It is made of stainless steel and has a through-structure. The bottom of the container 20 is detachably sealed to the base plate 13 for fixing and placing the sample. The container 20 is a split structure, comprising two shells 21. The two shells 21 are symmetrically arranged and detachably connected. The connection between the two shells 21 can be fixed by a fixing piece 22. To ensure sealing performance, a sealing strip can be provided at the connection between the two shells 21. The bottom of the shell 21 is sealed to the base plate 13. Several connecting holes 23 and several connecting pieces 24 are provided on the sides of the shell 21. The connecting holes 23 communicate with the interior of the container 20, and the connecting pieces 24 are detachably fixed to the shell 21.

[0044] Furthermore, the iron support 11 at the top of the test frame 10 is provided with a sliding groove 14. Two retractable tie rod assemblies 15 are slidably connected through the sliding groove 14. The two tie rod assemblies 15 are detachably connected to the connecting pieces 24 on the two housings 21. A control device is connected to the tie rod assemblies 15 to control their movement, thereby moving the two sets of components along the sliding groove 14 to achieve assembly and disassembly. That is, the two tie rod assemblies 15 drive the two sets of components to move relative to each other along the sliding groove 14 to the base plate 13 for splicing, or the two tie rod assemblies 15 drive the two sets of components to move away from the base plate 13 along the sliding groove 14, and then away from the experimental operation area 12 for disassembly. In practical applications, the tie rod assemblies 15 can be driven by a motor and a transmission structure to slide along the sliding groove 14.

[0045] The fixing piece 22 is embedded in the surface of the container 20, that is, it is set within the thickness of the side of the container 20. The surface of the fixing piece 22 is flush with the surface of the side of the container 20. The fixing piece 22 does not protrude from the outer surface of the container 20, so as to prevent the container 20 from not being in full contact with the water tank assembly 30. The pull rod assembly 15 can be extended or compressed, and can be moved and adjusted through its movable parts.

[0046] The connection point between the two bodies of container 20 serves as dividing line b, primarily used for disassembling container 20. When not conducting shear tests or directly performing compressive and crack resistance tests, the end of the tie rod assembly 15 is fixed to the connecting piece 24 of container 20. Container 20 is then disassembled and removed by operating the tie rod assembly 15. This ensures good sealing of container 20; even after alignment and assembly along dividing line b, good sealing is maintained, with no water or air leakage.

[0047] The container 20 has several detachable first fixing pieces 25 and several detachable second fixing pieces 26 on its sides. The first fixing pieces 25 are spaced apart along a first or second direction of the test frame 10 and can be located on the front and left and right sides of the container 20. The second fixing pieces 26 are spaced apart along the diagonal of the side of the container 20 and can be located on the left and right sides of the container 20. The front and back of the container 20 are positive shear surfaces 27, and the left and right sides of the container 20 are oblique shear surfaces 28.

[0048] In this invention, positive shear refers to the shear failure of the sample in container 20 under axial (i.e., vertical) pressure and radial thrust on the positive shear surface 27; oblique shear refers to the shear failure of the sample in container 20 under axial pressure and radial thrust on the oblique shear surface 28.

[0049] The first fixing piece 25 is used in the oblique shear test, that is, in the oblique shear test, the second fixing piece 26 is removed and the first fixing piece 25 is retained; the second fixing piece 26 is used in the normal shear test, that is, in the normal shear test, the first fixing piece 25 is removed and the second fixing piece 26 is retained; the first fixing piece 25 and the second fixing piece 26 are embedded in the surface of the container 20 and fixed by bolts 20a.

[0050] According to experimental needs, the present invention also includes several sealing layers 33, which can be inserted axially downward into the inner side of the water cavity 35 to seal the connecting hole 23. The sealing layers 33 are very thin and lightweight, possessing certain strength and rigidity, and are used to isolate the sample from the external solution. They can be used in undrained shear or consolidation undrained shear experiments with undrained measures. The sealing layers 33 can be moved upward and fixed in the desired position according to experimental needs. A breathable and water-permeable layer 34 (see [reference]) can also be provided between the sealing layers 33 and the inner wall of the water cavity 35. Figure 9 The orange part is breathable and water-permeable but not permeable to particles, preventing the sample placed in container 20 from being dispersed by the solution and lost from the connecting hole 23 during the experiment.

[0051] The container 20 of this invention can be configured as a cuboid, and a filling layer 29 is also provided inside the container 20. The filling layer 29 fills the gap between the sample and the inner side of the water cavity 35. The filling layer 29 is used to control the shape and size of the sample, keeping it as a cuboid or cylinder, etc. The filling layer 29 should be resistant to acid and alkali corrosion and chemical solvent corrosion, have air and water permeability, be not easily deformed, and have a certain rigidity and strength; the filling layer 29 may or may not be provided depending on the experimental requirements.

[0052] A fixing ring can also be set at the dividing line b of container 20. Two fixing rings can be set at the top and bottom of the front of container 20, and two fixing rings can also be set at the top and bottom of the opposite back. The main purpose is to fix and tightly connect the two sets of components that make up container 20 after container 20 is fixed, so as to ensure that container 20 is impermeable to water and air.

[0053] The water tank assembly 30 is slidably fitted with the chute 14 and has several water cavities 35 surrounding the outer periphery of the container 20 for injecting and storing solutions. The water cavities 35 can communicate with the container 20. The solutions can be solutions with different pH values, different salt ion concentrations and types, or even high-strength real filtrate. Specifically, the water tank assembly 30 adopts a split structure, comprising multiple water tanks 31, each located on a different side of the container 20 and slidably fitted with the chute 14. Each water tank 31 contains a water cavity 35, and a removable cover 36 is provided on the top of the water tank 31 to seal it. The cover 36 can be removed as needed for experiments. A movable inner side plate 32 is provided on one side of the water tank 31 relative to the container 20. The inner side plate 32 has a connecting hole 23, which communicates with a connecting hole 23 on the container 20 containing the sample to facilitate the solution to penetrate into the sample. The connecting holes 23 on the inner side plate 32 can be arranged in four rows, with four connecting holes 23 in each row, to facilitate the solution in the water tank 31 to enter the sample contained in the container 20. Connecting holes 23 can also be provided on other sides of the water tank 31 to communicate with adjacent water tanks 31. The inner side plate 32 of the water tank 31 can slide up and down and be fixed in the corresponding position, and can be operated during the experiment as needed.

[0054] On the side of the water tank 31 opposite to the inner side plate 32, there are also switchable drain holes 37 and switchable vent holes 38. The drain holes 37 are located at the bottom of the water tank 31, and each water tank 31 can have two drain holes 37 for draining the solution inside the water tank 31. Each water tank 31 can have two vent holes 38. When not in use, the valves of the vent holes 38 should be closed to prevent the solution in the water tank 31 from entering the equipment through the vent holes 38 and damaging the instrument. A venting line 30a is connected to the vent holes 38 of the water tank 31, and the other end of the venting line is connected to auxiliary equipment. The control device is connected to the auxiliary equipment to control the auxiliary equipment to blow out normal temperature air, hot air, or cold air.

[0055] At least one water tank 31 has a water inlet 39 and at least one temperature sensor 82 on its cover 36. The water inlet 39 is equipped with a removable sealing plug. The water inlet 39 can be located on the left or right side of the cover 36 of the water tank 31 of the container 20. The temperature sensor 82 can be located diagonally on the front or back of the cover 36 of the water tank 31 of the container 20. The temperature sensor 82 is connected to a control device and can monitor the temperature of the solution in the water tank 31 in real time. The temperature sensor 82 must also have appropriate waterproof, high-temperature resistant, and low-temperature resistant measures to ensure its normal use in experiments.

[0056] In the diagram, the water tank assembly 30 is divided into four water tanks 31 according to the four sides of the container 20. The bottom of each water tank 31 slides into the groove 14 to fix the position of the four different water tanks 31. The connection point between adjacent water tanks 31 serves as a disassembly line a, which allows the water tanks 31 to be disassembled. Depending on the experimental needs, when the water tank assembly 30 is not needed, the water tanks 31 can be disassembled according to the specific position of the disassembly line a and slid along the groove 14 to a position away from the experimental operation area 12.

[0057] In practical applications, the iron support 11 of the test frame 10 is used to support various parts of the experimental apparatus. It should have the corresponding strength and rigidity and appropriate protective measures to make it resistant to acid, alkali and chemical corrosion. The sliding groove 14 around the base on the iron support 11 is used to guide the movement and positioning of different water tanks 31 to different positions, and to guide the container 20 and the sample to different positions during the shearing process; the sliding groove 14 on the top iron support 11 of the test frame 10 is used to guide the multi-directional movement of the tie rod assembly 15.

[0058] The upper loading assembly 40 is vertically and vertically mounted on top of the container 20 to compact or axially load the sample inside the container 20. The upper loading assembly 40 includes an upper pressure plate 41, an upper telescopic rod 42, and an upper driving component 43. The upper pressure plate 41 is located above the container 20 and has an opening 44 with a removable cover 45. The upper telescopic rod 42 passes through the upper pressure plate 41 and has an upper drill bit 46 at its end, located within the opening 44 of the upper pressure plate 41. The upper driving component 43 is mounted on a top iron bracket 11 and connects to drive the upper pressure plate 41 and the upper telescopic rod 42 to rise or fall. The upper driving component 43 is equipped with a displacement sensor 81.

[0059] Furthermore, probe 47 is disposed in upper pressure plate 41, which has a small hole for storing probe 47. Probe 47 can be extended and retracted into the sample. The other end of probe 47 is connected to a control device, which uses related auxiliary equipment to monitor the moisture content inside the sample in real time.

[0060] A dial indicator 48 can also be installed on the upper pressure plate 41 of the upper loading component 40. It can be fixed in the corresponding position and zeroed according to experimental requirements. When the upper pressure plate 41 moves down to the preset position, it can be used to test the displacement and deformation of the sample or to monitor the degree of consolidation of the sample.

[0061] The lower loading assembly 50 is detachably connected to the base plate 13 and can be raised and lowered to adjust the axial position of the sample; the lower loading assembly 50 includes a lower pressure plate 51, a lower telescopic rod 52 and a lower driving component 53; the lower pressure plate 51 is detachably connected to the base plate 13 and is provided with an opening 44, and a detachable cover 45 is provided at the opening 44; the lower telescopic rod 52 passes through the lower pressure plate 51 and is provided with a lower drill bit 54 at its end, and the lower drill bit 54 is located in the opening 44 of the lower pressure plate 51; the lower driving component 53 connects and drives the lower pressure plate 51 and the lower telescopic rod 52 to rise or fall; a displacement sensor 81 is provided on the lower driving component 53.

[0062] In this invention, the upper and lower loading groups are used to apply axial pressure to the sample. The hydraulic rods of the upper drive member 43 and the lower drive member 53 are controlled by a control device to operate and monitor the axial deformation of the sample, thereby controlling the deformation of the sample and the magnitude of the applied axial force. The telescopic rod and drill bit are mounted on the upper pressure plate 41 and the lower pressure plate 51, primarily used for crack resistance testing to induce crack formation and sample failure. The upper drill bit 46 and the lower drill bit 54 are conical, their size determined by the diameter of the disc, and not exceeding the size of the opening 44 reserved in the upper and lower pressure plates 41. When crack resistance testing is not performed, the conical tip can be pressed into the upper pressure plate 41 via the telescopic rod, and a cover can be placed on top to ensure that the contact area between the pressure plate and the sample remains flat.

[0063] The circumferential loading assembly 60 is movably disposed within the water tank assembly 30 and can apply radial pressure to the sample. The circumferential loading assembly 60 includes several side pressure plates 61 and several side drive members 62. The side pressure plates 61 are respectively located in different water chambers 35 of the water tank assembly 30, and the several side drive members 62 are respectively connected to drive the corresponding side pressure plates 61 to move. Displacement sensors 81 are provided on the side drive members 62.

[0064] In this invention, multiple side pressure plates 61 are located in the front, back, left, and right water tanks 31 of the container 20, respectively, for applying radial pressure. The pressure is applied by controlling the hydraulic rod of the side drive member 62 through a control device, and confining pressure can also be applied through the solution in the water cavity 35 of the water tank assembly 30.

[0065] It also includes a shearing assembly 70, which is movably installed in the water tank assembly 30 and can shear and destroy the sample. The shearing assembly 70 includes several shearing plates 71 and several shearing drive members 72. The several shearing plates 71 are respectively located in different water chambers 35 of the water tank assembly 30, and the several shearing drive members 72 are respectively connected to drive the corresponding shearing plates 71 to move; several displacement sensors 81 are provided on the shearing drive members 72.

[0066] In this invention, shearing top plates 71 are installed in the water tanks 31 located on the front and back of the container 20 as forward shearing plates 71, and shearing plates 71 located in the water tanks 31 on the left and right sides of the container 20 as oblique shearing plates. In the shearing experiment, the second fixing plate 26 on the container 20 is fixed, the first fixing plate 25 is removed, and the forward shearing plate on the front or back is controlled to move in a specified direction so that the forward shearing surface 27 undergoes shearing failure. Alternatively, in the oblique shearing experiment, the first fixing plate 25 in the container 20 is fixed, the second fixing plate 26 is released or removed, and the oblique shearing plate is controlled to move so that the sample undergoes shearing failure along the oblique shearing surface 28. The shearing rate is controlled by the hydraulic rod of the shearing drive 72 via a control device.

[0067] Furthermore, the device of the present invention is also provided with rubber sleeves 49 for sealing the joints of different parts of the device to prevent water leakage. Specifically, rubber sleeves 49 are provided on the outer periphery of the cover plate 36 to seal the junction between the water tank 31 and the cover plate 36. Rubber sleeves 49 are provided at the joints between the hydraulic rods of each drive structure and the water tank 31 to prevent solution leakage, and at the same time to reduce the resistance of the hydraulic rods during extension and retraction.

[0068] The rubber sleeve 49 can also serve as a protective layer to protect the parts in contact with the solution in the water tank 31 from corrosion. It has strong elasticity, can be stretched and compressed, and is thin enough not to affect experimental operations. For example, the rubber sleeve 49 can be fitted over the side pressure plate 61 located inside the water cavity 35 of the water tank 31, and over the surface of the hydraulic rod located inside the water tank 31. The rubber sleeve 49 on the surface of the hydraulic rod can be compressed and stretched without plastic deformation or cracking.

[0069] The liftable base plate 13 is located above the lower pressure plate 51 and is the same size as the lower pressure plate 51, facilitating its upward movement with the lower pressure plate 51 during sample loading. In unconfined compressive and shear strength tests, the liftable base plate 13 is fixed to the surface of the lower pressure plate 51 by bolts 20a. A through slot 16 is provided in the middle of the base plate 13, and the slot 16 is equipped with a removable sealing sleeve 17. The size of the slot 16 is slightly larger than the maximum diameter of the lower drill bit 54 in the lower pressure plate 51, facilitating contact and loading of the lower drill bit 54 with the sample through the slot 16. During the crack resistance test, the sealing sleeve 17 can be pulled out to open the slot 16, but during the compressive and shear strength tests, the sealing sleeve 17 is used to block the slot 16, and the slot 16 remains closed throughout the sample preparation process, including saturation or consolidation.

[0070] In this invention, after the container 20 is placed on the base plate 13, a sealing rubber layer is provided at the bottom of the container 20, which has a good connection with the base plate 13 to ensure the airtightness (airtightness and water tightness) of the overall device. The base plate 13 has a certain thickness, and several connecting holes 19 are provided in the thickness direction around its perimeter. It also includes several support rods 18, one end of which is detachably connected to the connecting hole 19 of the base plate 13, and the other end is detachably connected to the test frame 10 to support the base plate 13 when it rises to the designed height. At this time, it is necessary to first disconnect the connection between the base plate 13 and the lower pressure plate 51. The lifting and lowering of the base plate 13 mainly relies on the driving of the lower pressure plate 51 and the lower driving component 53, and the support rods 18 are used to keep the position unchanged.

[0071] The displacement detection component includes several displacement sensors 81, which are respectively disposed on the upper loading component 40, the circumferential loading component 60, and the shear component 70 to detect displacement information. The control device is connected to the upper loading component 40, the lower loading component 50, the circumferential loading component 60, the shear component 70, and the displacement detection component to control the operation of each component and acquire displacement information.

[0072] The driving structure of the upper loading component 40, lower loading component 50, circumferential loading component 60, and shearing component 70 of this invention can be a hydraulic cylinder. Each hydraulic cylinder is equipped with a hydraulic rod, and each hydraulic rod is equipped with a displacement sensor 81 to detect displacement information. A control device is connected to each displacement sensor 81 to monitor the deformation (axial and radial) of the sample and the displacement of the hydraulic rod in real time, thereby determining whether the sample is damaged and stopping the experiment. Auxiliary equipment in this invention includes a vacuum pump, a blower dryer, and a small portable refrigerator.

[0073] Before testing, the device of the present invention requires the following operations:

[0074] 1) Disassemble the water tank assembly 30 into four water tanks 31 along the disassembly line a. Fix the position of the water tanks 31 by the slide groove 14 so that the water tanks 31 are far away from the center on the base plate 13. At the same time, the hydraulic rod in the water tank 31 changes with its position.

[0075] 2) Ensure that the first fixing piece 25 and the second fixing piece 26 on container 20 remain unchanged. Insert the sealing layer 33 downwards into container 20. Depending on experimental needs, a filling layer 29 may be added to control the shape of the sample. Divide container 20 into two sets along the dividing line b. Connect the connecting piece 24 of each set to the tie rod assembly 15. Use the control device to control the tie rod assembly 15 to move the two sets along the slide groove 14 and assemble them with the base plate 13. After container 20 is aligned and assembled, fix the fixing piece 22 on the dividing line b to ensure that container 20 becomes a complete unit.

[0076] 3) Control the movement of the lower pressure plate 51 of the loading component 50 to make it flush with the upper end of the slide groove 14 on the bottom iron bracket 11. Also control the telescopic rod in the lower pressure plate 51 to prevent the lower drill bit 54 from being pushed out (i.e., the surface of the lower pressure plate 51 is flat); similarly, control the telescopic rod in the upper pressure plate 41 to prevent the upper drill bit 46 from being pushed out (i.e., the surface of the upper pressure plate 41 is flat).

[0077] The probe 47 on the upper pressure plate 41 can be set or not, depending on the experimental requirements. When set, the probe 47 is inserted into the sample through the small hole of the upper pressure plate 41, and the changes in the moisture content and humidity inside the sample are observed in real time through auxiliary equipment. If not set, the probe 47 is removed and the small hole on the upper pressure plate 41 is closed.

[0078] 4) Calculate the required moisture content, dry density and compaction degree of the sample according to the experimental needs, pour the prepared material into container 20, and control the upper pressure plate 41 to descend and compact the sample.

[0079] Based on the above steps, the device of the present invention is used to perform an unconfined compressive strength test:

[0080] a1 controls the upper pressure plate 41 of the upper loading component 40 to perform hydraulic sample preparation on the sample in the container 20 through the control device, and controls the upper pressure plate 41 to rise back to its original position after the sample preparation is completed.

[0081] a2 connects the pull rod assembly 15 to the container 20, removes the fixing piece 22 on the surface of the container 20, and disassembles the container 20 into two sets (this process needs to be done slowly to avoid damaging the sample). Control the pull rod assembly 15 to move the container 20 out of the experimental operation area 12. At this time, the sample is completely exposed and placed on the lower pressure plate 51. The position of the sample can be adjusted to the appropriate position required for the experiment by the action of the lower pressure plate 51 of the lower loading assembly 50.

[0082] a3 controls the upper pressure plate 41 to move slowly downwards for loading test, and turns on the displacement sensor 81 on the hydraulic rod in advance before the test to detect and control the displacement of the sample.

[0083] The initial reading of the sample can also be determined by the position of the dial gauge 48. However, before that, the displacement sensor 81 and the control device must be used to ensure that the upper pressure plate 41 stops displacing and the axial pressure is stopped after it contacts the upper surface of the sample. The position of the dial gauge 48 is fixed in this gap, and then the control device is turned on again to start applying axial load to the sample until it fails.

[0084] a4 continues to apply axial pressure through the control device and monitors the axial deformation of the sample through the displacement sensor 81. The axial deformation of the sample is controlled according to the experimental needs (generally, the sample is considered to be damaged when the axial deformation is between 15% and 20%). The sample is considered to be fully damaged when the axial deformation is between 15% and 20%.

[0085] After the sample is destroyed, control the upper pressure plate 41 to stop its downward displacement and rise back to its initial state, thus ending the experiment.

[0086] The axial stress and axial strain of the specimen can be read, recorded and stored by displacement sensor 81 and related data acquisition device. The magnitude of the axial force of the specimen during the experiment can be monitored in real time by control device.

[0087] In this invention, the reference formula for unconfined compressive strength is as follows:

[0088] ① Axial strain of the specimen: ε=Δh / h0 Equation (1)

[0089] In the formula (1): ε is the axial strain, in %; Δh is the axial strain, and h0 is the initial height of the specimen, in mm;

[0090] ② Average area of ​​the sample: A a =A0 / (1-ε) Equation (2)

[0091] In equation (2): A a Cross-sectional area of ​​the sample after correction, initial area of ​​sample A0 before correction, in cm² 2 ;

[0092] ③ Axial stress of the specimen: σ=F / A a Equation (3)

[0093] In equation (3): σ is the axial stress, in kPa; F is the axial pressure, in kN; A a Cross-sectional area of ​​the sample after correction, in cm² 2 .

[0094] A σ-ε curve is typically plotted with axial stress σ as the ordinate and axial strain ε as the abscissa. The maximum axial stress is taken as the unconfined compressive strength. If the maximum axial stress is not significant, the stress at 15% of the axial strain is taken as the unconfined compressive strength of the specimen.

[0095] The device of the present invention can also be used to perform confined compressive strength tests:

[0096] The procedures for the confined compressive strength test are generally similar to those for the unconfined compressive strength test, with the following differences:

[0097] In hydraulic sample preparation, after the sample has fully solidified, the upper pressure plate 41 is not moved so that it contacts the sample surface but no axial pressure is applied; the slot 16 at the center of the bottom plate 13 under the container 20 is always closed by the sealing sleeve 17, and a rubber sleeve 49 is provided around the sealing sleeve 17 to ensure good airtightness of the device and prevent the sample from leaking out.

[0098] Without removing container 20, only the surface fixing plates of container 20 are removed, allowing container 20 to move during subsequent loading, thereby amplifying the deformation of the sample. At the same time, the connection between tie rod assembly 15 and container 20 is released.

[0099] The inner side plates 32 of the four water tanks 31 are moved upward to a suitable position and fixed, so that the side pressure plates 61 inside the water tanks 31 can extend out of the water tanks 31; the side pressure plates 61 of the circumferential loading assembly 60 are controlled to move to the four surfaces of the container 20, and a certain confining pressure is applied to the sample in the container 20 according to the experimental requirements.

[0100] Steps a3-a5 remain unchanged, but during this loading process, it is not necessary to use dial gauge 48 to monitor and control the deformation of the sample; instead, displacement sensor 81 on the hydraulic rod is used for real-time monitoring.

[0101] The lateral confined compressive strength is obtained directly from the corresponding data acquired by the control device, yielding the compressive strength of the specimen under different confining pressures.

[0102] Crack strength test operation

[0103] In the crack strength test, the operation steps before the test are the same as steps 1)-4); however, during the operation, the containers 20 on both sides of the sample need to be removed. At this time, the upper pressure plate 41 should be far away from the upper surface of the sample, that is, the sample is not subject to axial load.

[0104] b1 connects support rods 18 to the connecting holes 19 around the base plate 13, and after controlling the lower pressure plate 51 to rise to the designed height, fixes the support rods 18 around the base plate 13 to the test frame 10 to support the base plate 13 and the sample. Open the slot 16 of the base plate 13 to facilitate the lower drill bit 54 on the lower pressure plate 51 to contact the sample and apply load.

[0105] b2 controls the lower pressure plate 51 to move downwards and detach from the base plate 13. The detachment distance must ensure that the probe in the lower pressure plate 51 can extend smoothly without touching the sample (damaging the sample). Therefore, before preparing the sample for the crack strength test, the bolts fixing the base plate 13 and the lower pressure plate 51 must be unscrewed in advance to ensure that the base plate 13 and the lower pressure plate 51 can be separated smoothly.

[0106] b3 Open the slots 16 on the upper pressure plate 41 and the lower pressure plate 51, and slowly extend the upper drill bit 46 and the lower drill bit 54 from the upper pressure plate 41 and the lower pressure plate 51 through the telescopic rod to induce the generation of cracks and study the crack resistance of the sample.

[0107] According to the needs of the experiment, the extension rate of the drill bit carried by the telescopic rod can be controlled by the control device during this process; according to the needs of the experiment, the size of the drill bit in the upper pressure plate 41 and the lower pressure plate 51 can be changed in advance.

[0108] b4 controls the upper drill bit 46 tip of the upper pressure plate 41 to move to be flush with the sample surface (at this time, no axial pressure is applied to the sample), and stops the displacement of the upper pressure plate 41; controls the lower drill bit 54 tip of the lower pressure plate 51 to move to be flush with the sample surface, at which time the probe passes through the pre-reserved slot 16 at the center of the base plate 13 (at this time, no axial pressure is applied to the sample), and stops the displacement of the lower pressure plate 51. This process can realize the storage and recording of measured data through displacement sensor 81 and related signal data acquisition device, and combined with the remote control device to control the contact between the upper pressure plate 41 and the upper surface of the sample.

[0109] By fixing the position of the dial gauge 48 and recording its initial reading, and then ensuring that the fixed positions of the upper pressure plate 41 and the lower pressure plate 51 do not change, the sample is clamped between the upper pressure plate 41 and the lower pressure plate 51 without applying a load to it; this process can also be achieved by remote joint control of the displacement sensor 81 and its auxiliary equipment and control device.

[0110] b5 controls the upper pressure plate 41 and lower pressure plate 51 with drill bits to move relative to each other simultaneously. The two move at the same speed to load the sample, and at the same time monitor the displacement, stress, strain and ultimate load of the sample. It can also record the crack development on the surface of the sample during the experiment until the sample is destroyed.

[0111] See Figure 14 If, during the loading process, the displacement of the lower drill bit 54 in the lower pressure plate 51 exceeds the height reserved in advance by the base plate 13 before the experiment, and the sample still fails to reach the ultimate load, then the base plate 13 will move upward together with the lower pressure plate 51 until the sample fails.

[0112] The crack resistance of the specimen is calculated according to the following formula:

[0113]

[0114] In equation (4): δ w The relative velocity vector at each point along the surface of the cone; θ is the angle (°) formed by the relative velocity vector and the surface; q u α is the ultimate load of the specimen, in kN; b is the cone angle, in °; a and h are the specimen dimensions, in mm.

[0115] When α satisfies the condition бP / бα=0, the crack resistance strength of equation (4) can be simplified to:

[0116] σ t =P / [π(Mbh-b 2 Equation (5)

[0117] In formula (5) The value of M depends not only on the friction angle It also depends on the compressive-tensile strength ratio and the sample punch size ratio, where P is the axial load in kN.

[0118] Shear strength test procedure

[0119] Before the shear test, the specific experimental steps are the same as those described in steps 1)-4). According to the experimental requirements, the prepared sample can be consolidated before shearing. During the shear test, the container 20 is not disassembled, its bottom is connected to the bottom plate 13, and the airtightness (airtight and watertight) of the joint of the device is ensured. During the shearing process, the connection between the tie rod assembly 15 and the container 20 is disconnected.

[0120] Before the shearing process, the shearing top plate is first made to contact the surface of the container 20. At this time, the inner side plate 32 of the water tank 31 is first moved upward to a suitable position and fixed, so as to ensure that the shearing top plate can be moved to the surface of the container 20. The shearing test is divided into unconsolidated and undrained shearing test, consolidated and undrained shearing test, and consolidated and drained shearing test.

[0121] If unconsolidated and undrained shearing is performed, the sealing layer 33 is inserted downward into the container 20 so that water is not drained during the shearing process, and the upper pressure plate 41 is controlled by the control device to apply the corresponding axial load on the sample surface while directly shearing failure.

[0122] If a consolidation undrained shearing is performed, the upper pressure plate 41 is controlled to apply consolidation pressure to the sample, allowing it to fully consolidate under this pressure. At this time, the sealing layer 33 is moved upward to the corresponding position and fixed to ensure that the material is fully consolidated before shearing. After the sample is fully consolidated, the sealing layer 33 is moved downward and fixed in the container 20, and shearing is performed on it. During this process, the moisture in the sample is not allowed to be discharged.

[0123] If consolidation and drainage shearing are to be performed, fix the position of dial gauge 48 and record its initial reading. Then, ensure that the fixed positions of the upper pressure plate 41 and the lower pressure plate 51 do not change, allowing the sample to be clamped between the upper and lower pressure plates without applying any load. This process can also be achieved by combining the information detected by displacement sensor 13 with the control device. The difference is that during the consolidation and shearing process, the position of the sealing layer 33 is always moved to the outside of the container 20 and fixed, ensuring that the sample is fully drained, consolidated, and sheared throughout the process.

[0124] During the consolidation process, the axial deformation of the sample was monitored using a dial gauge 48, and relevant parameters such as the soil sample's compression coefficient, compression modulus, resilient modulus, and porosity were calculated.

[0125] After the sample consolidation process is completed and before the shear test begins, a suitable shear direction is selected to shear the sample. If it is necessary to break the sample along the normal shear plane 27, the first fixing plate 25 is opened and the second fixing plate 26 is tightened. If it is necessary to break the sample along the oblique shear plane 28, the second fixing plate 26 is opened and the first fixing plate 25 is tightened.

[0126] After consolidation is completed, the required shear direction is selected according to the experimental needs. The shear plate is controlled by the control device to conduct shear tests on the specimen under various loads. The displacement, stress and strain of the specimen during the shearing process are monitored by the information detected by the displacement sensor 81 on the shear assembly 70. Combined with the information from the remote end of the control device, the ultimate load that the specimen can withstand when shear failure occurs is obtained.

[0127] The shear strength of the specimen is calculated using the following formula:

[0128] W = P x Equation (6)

[0129] In equation (6), P is the failure load in kN; x represents the displacement of the specimen when it fails in the direction of P in mm.

[0130] The shear strength of the specimen is calculated using the following formula:

[0131]

[0132] In equation (7), σ is the normal stress, in kPa. θ is the internal friction angle, in degrees (°), and c is the soil cohesion, in kPa.

[0133] Procedure for saturation test of sample

[0134] For the above-mentioned strength issues, if the corresponding strength test is carried out after the material is saturated or cured, the following basic operation can be combined with various strength tests.

[0135] c1. According to steps 1)-4), place the prepared sample in container 20 and keep it stationary. At the point where the upper pressure plate 41 contacts the top surface of the sample, disconnect the connection between container 20 and pull rod assembly 15; and check whether the sealing performance of the device is good.

[0136] Check if the water tank 31 is airtight. Cover the upper part of the water tank 31 with the cover plate 36 and ensure good airtightness. Keep the inner side plate 32 of the water tank 31 in place. Close the drain hole 37 at the bottom of the water tank 31 and the vent hole 38 at the top.

[0137] After the side pressure plates 61 on the front, back, and left and right sides of the device are slowly brought into contact with the partition of the water tank 31, the movement of the side pressure plates 61 drives the four water tanks 31 to move towards the container 20 and make them in close contact with the container 20. The movement stops, and the side pressure plates 61 are forced to retract so as not to block the connecting holes 23 on the inner side plate 32. The alignment of the connecting holes 23 of adjacent water tanks 31 is checked, and the airtightness of the device is checked again.

[0138] Before filling the water tank 31 with water, ensure that the sealing layer 33 in the container 20 is inserted into the bottom of the container 20. Fill the water tank 31 with solution through the water injection hole 39 (the solution is designed according to the needs), and then close the water injection hole 39. Remove the sealing layer 33 to saturate the sample (the saturation time is designed according to the experimental needs).

[0139] c4 For the sample after saturation, first reinsert the sealing layer 33 to the bottom of the container 20, open the drain hole 37 and connect the corresponding collection container 20 to completely drain the solution in the water tank 31.

[0140] c5 controls the hydraulic rod through the control device to slowly bring the side pressure plate 61 into contact with the outside of the water tank 31, and then continues to use the control device to move the surrounding water tanks 31 away from the container 20 so as to completely separate them from the container 20.

[0141] After c6, the unconfined compressive strength test of the saturated specimen can be completed by using the unconfined compressive strength test procedure described above; the confined compressive strength test of the saturated specimen can be completed by combining the confined compressive strength test procedure; the crack strength test of the saturated specimen can be completed by combining the crack strength test procedure; and the shear strength test of the saturated specimen can be completed by combining the shear strength test procedure.

[0142] Procedure for wet-dry or freeze-thaw cycle testing of samples

[0143] Before performing the wet-dry cycle operation on the sample, install and fix the container 20 containing the sample according to steps 1)-4); move the water tank 31 to the outer surface of the container 20 and make it in close contact with it according to the above steps c1-c2.

[0144] During the d1 dry-wet cycle, first check whether the airtightness of the device is good, and ensure that the cover plate 36 on the water tank 31 is airtight; check that the water injection hole 39 on the cover plate 36 is closed; ensure that the drain hole 37 of the water tank 31 is closed; ensure that the vent hole 38 is closed; check whether the contact point between the water tank 31 and the container 20 is wrapped with a rubber sleeve (to ensure airtightness); ensure that the lower pressure plate 51 is in full contact with the bottom plate 13 under the container 20.

[0145] After the sealing layer 33 is removed from the container 20, a rubber sleeve 49 is put on the upper pressure plate 41 at the junction with the container 20 and on the surface of the container 20 in the circumferential direction to ensure the airtightness of the device.

[0146] d 3 Open the vent 38 (sideways), and control the external blower dryer of the vent 38 (sideways) to blow dry the sample. Hot air enters the sample through the communication hole 23 between the water tank 31 and the container 20. The wind speed and temperature of the hot air are adjusted by the control device and monitored in real time by the temperature sensor 82 on the cover plate 36 of the water tank 31. At the same time, the change of moisture content of the sample can be monitored by the probe 47 on the upper pressure plate 41, and the drying state is controlled in combination with the moisture content of the sample.

[0147] d 4 After the test drying is completed, turn off the power to the vent 38 (upper part) and the blower dryer; evacuate the sample in the test through the vent 38 and the external vacuum pump, and close the vent 38 (upper part) after the evacuation is completed.

[0148] d 5 Then, the solution (designed as needed) is injected into the water tank 31 through the water injection hole 39 to saturate the sample; after the sample is saturated, the solution is discharged through the drain hole 37.

[0149] The steps in the freeze-thaw cycle are basically the same as those in the wet-dry cycle above, with only a slight modification in step d3: during the freezing process, the cover plate 36 is opened and a small portable cooler is placed in the water tank 31, and then the cover plate 36 is resealed with the water tank 31.

[0150] The sample is dried in conjunction with a forced-air drying oven via vent 38 (sideways), with the forced-air temperature set to approximately 0°C. The cooler is turned on and, in conjunction with vent 38, cold air is blown into the sample through the connecting hole 23 to complete the freezing process. Temperature monitoring can be achieved during this process using the temperature sensor 82 at the cover plate 36. The melting process of the sample is the same as step d4, but the step of using a vacuum pump to remove air is omitted.

[0151] The above steps are a single dry-wet or freeze-thaw cycle process. Different numbers of dry-wet or freeze-thaw cycles can be set according to experimental needs. The relevant mechanical properties can be tested according to step c6.

[0152] The testing instrument of this invention integrates the compressive strength, crack resistance, and shear strength that are currently the main focus of soil research, and realizes the unification and simplification of the relevant mechanical property testing of materials under dry-wet or freeze-thaw cycle effects or simulated different complex environmental conditions.

[0153] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A tester for the mechanical properties of soil under wet-dry or freeze-thaw cycles, characterized in that, The system includes a test frame, a container, a water tank assembly, an upper loading component, a lower loading component, a circumferential loading component, a shearing component, a displacement detection component, and a control device. The test frame contains an experimental operation area, the bottom of which has a movable base plate and several sliding grooves. The sliding grooves are located on the outer periphery of the base plate and extend along a first or second direction. The container is vertically continuous and its bottom is detachably sealed to the base plate for placing a sample. The water tank assembly is slidably fitted with the sliding grooves and has several water cavities surrounding the outer periphery of the container for injecting solution; these water cavities can communicate with the container. The upper loading component is vertically and vertically mounted on top of the container to compact the sample or apply axial loading. The lower loading component is detachably connected to the base plate and can be raised and lowered to adjust the axial position of the sample. The circumferential loading component is movably inserted through the water tank assembly and can... Radial pressure is applied to the sample; the shearing assembly is movably inserted through the water tank assembly and can shear and destroy the sample; the displacement detection assembly includes several displacement sensors, which are respectively disposed on the upper loading assembly, the circumferential loading assembly, and the shearing assembly to detect displacement information; the control device is connected to the upper loading assembly, the lower loading assembly, the circumferential loading assembly, the shearing assembly, and the displacement detection assembly; the container includes two shells; the two shells are symmetrically arranged and detachably connected, the bottom of the shell is sealed to the base plate, and the sides of the shell are provided with several connecting holes and several connecting pieces; the test frame is provided with two retractable tie rod assemblies, which are detachably connected to the connecting pieces on the two shells; the control device is connected to the tie rod assemblies to control their movement to drive the two shells to move along the slide groove to achieve disassembly and assembly.

2. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The container has several detachable first fixing pieces and several detachable second fixing pieces on its side. The several first fixing pieces are spaced apart along a first direction or a second direction of the test frame. The several second fixing pieces are spaced apart along the diagonal of the side of the container.

3. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 2, characterized in that, It also includes several sealing layers, which can be inserted axially into the inside of the water cavity to seal the connecting hole so as to facilitate non-drain shearing. A breathable and water-permeable layer can also be provided between the sealing layer and the inner wall of the water cavity; or the container is also provided with a filling layer, which fills the gap between the sample and the inside of the water cavity to control the shape of the sample.

4. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The water tank assembly includes multiple water tanks, which are located on different sides of the container and slide in conjunction with the chute. Each water tank contains a water cavity, and each water tank has a removable cover plate on its top. An axially movable inner side plate is provided on the side of each water tank opposite to the container, and the inner side plate has the communicating hole. A drain hole and a vent hole are also provided on the side of each water tank opposite to the inner side plate. At least one water tank has a water injection hole and a temperature sensor on its cover plate, and the water injection hole has a removable sealing plug.

5. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 3, characterized in that, The base plate has a through slot in the middle, and the slot is equipped with a removable sealing sleeve; it also includes a number of support rods, one end of which is detachably connected to the base plate, and the other end is detachably connected to the test frame to support the base plate when it is raised to the design height.

6. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The upper loading assembly includes an upper pressure plate, an upper telescopic rod, and an upper driving component. The upper pressure plate is located above the container and has an opening with a removable cover. A removable probe is also provided on the upper pressure plate to insert into the sample to detect moisture content or humidity. The upper telescopic rod passes through the upper pressure plate and has an upper drill bit at its end, which is located inside the opening of the upper pressure plate. The upper driving component connects and drives the upper pressure plate and the upper telescopic rod to rise or fall, and a displacement sensor is provided on the upper driving component.

7. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The lower loading assembly includes a lower pressure plate, a lower telescopic rod, and a lower drive component; the lower pressure plate is detachably connected to the base plate and has an opening, with a detachable cover at the opening; the lower telescopic rod passes through the lower pressure plate and has a lower drill bit at its end, the lower drill bit being located within the opening of the lower pressure plate; the lower drive component connects and drives the lower pressure plate and the lower telescopic rod to rise or fall, and the lower drive component is equipped with the displacement sensor.

8. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The circumferential loading assembly includes several side pressure plates and several side drive components. The several side pressure plates are respectively located in different water chambers of the water tank assembly. The several side drive components are respectively connected to drive the corresponding side pressure plates to move. The displacement sensor is provided on the side drive component.

9. The soil mechanical property testing instrument under wet-dry or freeze-thaw cycle effects as described in claim 1, characterized in that, The shearing assembly includes several shearing plates and several shearing drive components. The shearing plates are located in different water chambers of the water tank assembly, and the shearing drive components are respectively connected to drive the corresponding shearing plates to move. Several displacement sensors are provided on the shearing drive components.

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