Mechanical property tester for soil body under dry-wet or freeze-thaw cycle effect

Abstract

The invention discloses a mechanical property tester for a soil body under a dry-wet or freeze-thaw cycle effect. The mechanical property tester comprises a test frame, a container, a water tank group, an upper loading assembly, a lower loading assembly, an annular loading assembly, a shearing assembly, a displacement detection assembly, a control device and the like, the testing frame is provided with a bottom plate and a plurality of sliding grooves. The bottom of the container is in detachable sealing fit with the bottom plate; the water tank group is used for injecting a solution; the upper loading assembly is used for carrying out compaction sample preparation or axial loading on the sample in the container; the lower loading assembly adjusts the axial position of the sample; the annular loading assembly applies radial pressure to the sample; the shearing assembly is used for shearing and damaging the sample; the displacement detection assembly is arranged on the upper loading assembly, the annular loading assembly and the shearing assembly; the control device is connected with the upper loading assembly, the lower loading assembly, the annular loading assembly, the shearing assembly and the displacement detection assembly. According to the invention, the function of continuously testing the mechanical properties by using a single sample and single equipment without taking out the sample is realized, and the corresponding operation steps and equipment are greatly simplified.

Description

Technical Field

[0001] The invention relates to the field of soil performance testing, in particular to a soil mechanical performance testing instrument under dry-wet or freeze-thaw cycle effects. Background Art

[0002] The impact of environmental issues on soil performance is particularly obvious, especially the dry-wet or freeze-thaw cycle effects on soil caused by multiple factors such as seasonal changes, surface runoff, the rise or fall of groundwater levels, and the temperature difference between day and night. It is worth studying. The dry-wet or freeze-thaw cycle effects will deteriorate the mechanical properties of the material and cause dangerous engineering situations such as slope instability, foundation pit collapse, sand liquefaction, and sudden drop in strength.

[0003] At present, most of the experimental devices for testing the mechanical properties of geotechnical materials are single-performance tests, and the equipment occupies a large area and is expensive. It is impossible to achieve rapid testing of multiple mechanical properties in one. In addition, these methods are cumbersome and the samples are easily disturbed during the experiment, affecting the measurement accuracy. Therefore, it is necessary to develop a new type of soil mechanical properties testing equipment to solve the above problems. Summary of the invention

[0004] The main purpose of the present invention is to overcome the above-mentioned defects in the prior art and to provide a mechanical property tester for soil under dry-wet or freeze-thaw cycle effects, which can detect various properties of the soil.

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

[0006] A mechanical property tester for soil under the effects of dry-wet or freeze-thaw cycles, characterized in that it comprises a test frame, a container, a water tank group, an upper loading component, a lower loading component, a circumferential loading component, a shearing component, a displacement detection component and a control device; an experimental operation area is arranged in the test frame, and a movable bottom plate and a plurality of slide grooves are arranged on the bottom surface of the experimental operation area, and the slide grooves are located on the periphery of the bottom plate and extend along a first direction or a second direction; the container is connected from top to bottom and the bottom and the bottom plate are detachably sealed to place a sample; the water tank group and the slide groove are slidably matched and are provided with a plurality of water cavities surrounding the periphery of the container for injecting a solution, and the water cavity can be connected to the container; the upper loading component can be raised and lowered and arranged on the bottom of ... The top of the container is used to compact the sample in the container or to perform axial loading; the lower loading component is detachably connected to the bottom plate and can be raised and lowered to adjust the axial position of the sample; the annular loading component is movably arranged in the water tank group and can apply radial pressure to the sample; the shearing component is movably arranged in the water tank group and can perform shear damage on the sample; the displacement detection component includes a plurality of displacement sensors, and the plurality of displacement sensors are respectively arranged on the upper loading component, the annular loading component and the shearing component to detect displacement information; the control device is connected to the upper loading component, the lower loading component, the annular loading component, the shearing component and the displacement detection component.

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

[0008] The side of the container is provided with a plurality of detachable first fixing plates and a plurality of detachable second fixing plates, wherein the plurality of first fixing plates are distributed at intervals along the first direction or the second direction of the test frame; and the plurality of second fixing plates are distributed at intervals along the diagonal line of the side of the container.

[0009] It also includes a plurality of sealing layers, which can be axially inserted into the inner side of the water cavity to close the connecting hole to facilitate non-drainage shearing, and a breathable and water-permeable layer can be arranged between the sealing layer and the inner wall of the water cavity; or a filling layer is also arranged in the container, and the filling layer fills the gap between the sample and the inner side of the water cavity to control the shape of the sample.

[0010] The water tank group includes a plurality of water tanks, which are respectively located on different sides of the container and slidingly cooperate with the slide groove; the water cavity is arranged in the water tank, a removable cover plate is arranged on the top of the water tank, an axially movable inner plate is arranged on the side of the water tank opposite to the container, the inner plate is provided with the connecting hole, and a switchable drainage hole and a switchable ventilation hole are also arranged on the side of the water tank opposite to the inner plate; a water injection hole and a temperature sensor are arranged on the cover plate of at least one of the water tanks, and a removable sealing plug is arranged on the water injection hole.

[0011] The bottom plate is provided with a through slot in the middle, and a detachable sealing sleeve is provided in the slot; a plurality of support rods are also provided, one end of each support rod is detachably connected to the bottom plate, and the other end is detachably connected to the test stand to support the bottom plate when the bottom plate rises to a designed height.

[0012] The upper loading assembly includes an upper pressure plate, an upper telescopic rod and an upper driving member; the upper pressure plate is located above the container and is provided with an opening, a detachable cover is provided at the opening, and a detachable probe is also provided on the upper pressure plate to insert the sample to detect the moisture content or humidity; the upper telescopic rod is passed through the upper pressure plate and an upper drill bit is provided at the end, and the upper drill bit is located in the opening of the upper pressure plate; the upper driving member is connected to drive the upper pressure plate and the upper telescopic rod to rise or fall, and the upper driving member is provided with the displacement sensor.

[0013] The lower loading assembly includes a lower pressure plate, a lower telescopic rod and a lower driving member; the lower pressure plate is detachably connected to the base plate and is provided with an opening, and a detachable cover is provided at the opening; the lower telescopic rod is passed through the lower pressure plate and a lower drill bit is provided at the end thereof, and the lower drill bit is located in the opening of the lower pressure plate; the lower driving member is connected to drive the lower pressure plate and the lower telescopic rod to rise or fall, and the lower driving member is provided with the displacement sensor.

[0014] The annular loading assembly includes a plurality of side pressure plates and a plurality of side driving members, wherein the plurality of side pressure plates are respectively located in different water chambers of the water tank group, and the plurality of side driving members are respectively connected to drive the corresponding side pressure plates to move, and the side driving members are provided with the displacement sensors.

[0015] The shearing assembly includes a plurality of shearing plates and a plurality of shearing driving members, wherein the plurality of shearing plates are respectively located in different water chambers of the water tank group, and the plurality of shearing driving members are respectively connected to drive the corresponding shearing plates to move, and the shearing driving members are provided with a plurality of displacement sensors.

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

[0017] The invention provides a mechanical property tester for soil under dry-wet or freeze-thaw cycle effects, comprising a test frame, a container, a water tank group, an upper loading component, a lower loading component, a circumferential loading component, a shear component, a displacement detection component and a control device, etc., realizing the function of continuously testing mechanical properties (compression resistance, crack resistance and shear resistance) of a single sample and a single device without taking out the sample, greatly simplifying the corresponding operation steps and equipment, and eliminating the influence of sample loss caused by human factors or improper operation on the test results.

[0018] The tester of the present invention can be divided into two parts: the first part is the sample making part of the sample, and the second part is the core testing part of the device. Before the sample is formally loaded into the test instrument, it is necessary to control the quality of the sample based on the optimal moisture content and maximum dry density obtained by the compaction test. Fix the stainless steel container on the upper part of the lower pressure plate and add the sample into it. Control the hydraulic rod through the computer to move the upper pressure plate down to the surface of the sample to hydraulically form the sample for 1 to 2 hours. Ensure whether the upper pressure plate is removed as needed; and ensure whether the annular water tank is moved around the stainless steel container as needed to saturate the sample, dry-wet or freeze-thaw cycle; then control the hydraulic rod through the computer to test the relevant mechanical properties of the sample.

[0019] The present invention can be applied to compressive strength test (unconfined or confined), crack strength test (degree of induced crack development), conventional shear strength test (drained or undrained), oblique shear test, and consolidation test. At the same time, dry-wet or freeze-thaw cycles can be simulated in the experiment, and the influence of different salt ions and different degrees of solution pH values ​​on the mechanical properties of materials in the natural environment can be simulated.

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

[0021] (a) Testing of mechanical properties 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, and testing of relevant mechanical properties after multiple cycles as needed;

[0022] (b) According to the experimental requirements, whether to conduct dry-wet or freeze-thaw cycles under the action of overlying loads and to conduct mechanical property tests after solidification of different solutions can be controlled. The force loading range in the experiment is between 0 and 3.0 MPa (depending on the pressure (thrust) in the experiment and the specific material of the experimental device). BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 A top view of the present invention;

[0025] Figure 3 It is the coordination diagram of the water tank group and each loading component;

[0026] Figure 4 It is the coordination diagram of the water tank group and each loading component (displacement sensor);

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

[0028] Figure 6 It is a schematic diagram of the positions of each loading component and the specimen;

[0029] Figure 7 For single tank and loading assembly Figure 1 ;

[0030] Figure 8 For single tank and loading assembly Figure 2 ;

[0031] Fig. 9 It is a container structure diagram;

[0032] Fig.10 It is a side view of the container;

[0033] Fig.11 The bottom plate structure diagram;

[0034] Fig.12 This is the coordination diagram between the bottom of the water tank and the chute;

[0035] Fig.13 This is a diagram showing the cooperation between the first fixing plate and the container;

[0036] Fig.14 This is a schematic diagram of the failure of the specimen in the cracking strength test;

[0037] Among them: 10, test frame; 11, iron bracket, 12, experimental operation area; 13, bottom plate; 14, slide groove, 15, pull rod group; 16, notch; 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 group, 31, water tank, 32, inner plate, 33, sealing layer; 34, air-permeable and water-permeable layer; 35, water cavity; 36, Cover plate; 37, drainage hole; 38, vent hole; 39, water injection hole; 40, upper loading assembly; 41, upper pressure plate; 42, upper telescopic rod; 43, upper drive member; 44, opening, 45, cover body; 46, upper drill bit; 47, probe; 48, dial indicator; 49, rubber sleeve; 50, lower loading assembly; 51, lower pressure plate; 52, lower telescopic rod; 53, lower drive member; 54, lower drill bit; 60, circumferential loading assembly; 61, side pressure plate; 62, side drive member; 70, shear assembly; 71, shear plate; 72, shear drive member; 81, displacement sensor, 82, temperature sensor.

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0039] The present invention is further described below through specific implementation modes.

[0040] In the present invention, the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. In the description, the directions or positional relationships indicated by "upper", "lower", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and are not intended to indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In addition, in the description of this application, unless otherwise specified, "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0042] See also Figures 1 to 13A mechanical property tester of soil under dry-wet or freeze-thaw cycle effects, comprising a test frame 10, a container 20, a water tank group 30, an upper loading assembly 40, a lower loading assembly 50, a circumferential loading assembly 60, a shear assembly 70, a displacement detection assembly and a control device. The test frame 10 comprises a plurality of iron brackets 11, which are connected to form an experimental operation area 12. The experimental operation area 12 is used to perform various test experiments. The iron brackets 11 on the bottom of the experimental operation area 12 are provided with a movable bottom plate 13 and a plurality of chutes 14. The iron brackets 11 on the bottom are provided with a clearance opening to make way for the bottom plate 13. The chutes 14 are located on the iron brackets 11 on the bottom. The chutes 14 are located on the periphery of the clearance opening and extend along the first direction or the second direction. The first direction and the second direction are perpendicular, that is, part of the chutes 14 extend along the first direction, and part of the chutes 14 extend along the second direction. The specific number is not limited and is set according to actual needs.

[0043] The container 20 of the present invention is the core container 20 of the sample, which is made of stainless steel and has a through structure. The bottom of the container 20 is detachably sealed with the bottom plate 13 for fixing and placing the sample. The container 20 is arranged as a separate structure, which includes two shells 21. The two shells 21 are symmetrically arranged and detachably connected. The connection between the two shells 21 can be fixedly connected by a fixing plate 22. In order to ensure the sealing performance, a sealing strip can be set at the connection between the two shells 21 for sealing. The bottom of the shell 21 is sealed with the bottom plate 13. The side of the shell 21 is provided with a plurality of connecting holes 23 and a plurality of connecting plates 24. The connecting holes 23 are connected to the inside of the container 20, and the connecting plates 24 are detachably fixedly connected with the shell 21.

[0044] Furthermore, the iron bracket 11 at the top of the test stand 10 is provided with a slide groove 14, through which two retractable tie rod groups 15 are slidably connected, and the two tie rod groups 15 are detachably connected to the connecting pieces 24 on the two shells 21. The control device is connected to the tie rod group 15 to control its movement to drive the two sets of bodies to move along the slide groove 14 to achieve disassembly and assembly, that is, the two tie rod groups 15 drive the two sets of bodies to move relatively along the slide groove 14 to the bottom plate 13 to achieve splicing, or the two tie rod groups 15 drive the two sets of bodies to leave the bottom plate 13 along the slide groove 14, and then leave the experimental operation area 12 to achieve disassembly. In actual applications, the tie rod group 15 can be driven by a motor in conjunction with a transmission structure to slide along the slide 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 cannot protrude from the outer surface of the container 20 to prevent the container 20 from not being able to fully contact the water tank assembly 30. The pull rod assembly 15 can be extended or compressed, and can be moved and adjusted through the movable parts therein.

[0046] The connection between the two sets of the container 20 is used as a dividing line b, which is mainly used to disassemble the container 20. When the shear test is not performed or the compression and crack resistance test is performed directly, the end of the tie rod group 15 is fixed on the connecting piece 24 of the container 20, and the container 20 is disassembled and removed by operating the tie rod group 15. Ensure that the container 20 has good sealing performance, and the container 20 can still maintain good sealing performance after being aligned and assembled along the dividing line b of the container 20, and it is watertight and airtight.

[0047] The side of the container 20 is provided with a plurality of detachable first fixing plates 25 and a plurality of detachable second fixing plates 26. The plurality of first fixing plates 25 are spaced apart along the first direction or the second direction of the test frame 10, and the plurality of first fixing plates 25 can be located on the front and left and right sides of the container 20. The plurality of second fixing plates 26 are spaced apart along the diagonal lines of the side of the container 20, and the plurality of second fixing plates 26 can be located on the left and right sides of the container 20. The front and back sides 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 the present invention, forward shear refers to the shear failure of the sample in the container 20 at the forward shear surface 27 under axial, i.e., vertical pressure and radial thrust; oblique shear refers to the shear failure of the sample in the container 20 at the oblique shear surface 28 under axial pressure and radial thrust.

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

[0050] According to the experimental needs, the present invention also includes a plurality of sealing layers 33, which can be inserted axially downward into the inner side of the water cavity 35 to close the connecting hole 23. The sealing layer 33 is very thin and lightweight and has a certain strength and rigidity, and is used to isolate the sample from the external solution. It can be used in the undrained shear or consolidated undrained shear test. The sealing layer 33 can be moved upward and fixed at the desired position according to the experimental needs. A breathable and water-permeable layer 34 can also be set between the sealing layer 33 and the inner wall of the water cavity 35 (see Fig. 9 The orange part in the middle is permeable to air and water but not to particles, so as to prevent the sample placed in the container 20 from being dispersed by the solution and lost from the connecting hole 23 during the experiment.

[0051] The container 20 of the present invention can be set to be a rectangular parallelepiped, and a filling layer 29 is also provided in the container 20, and 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, so that it remains a rectangular parallelepiped or a cylinder, etc. The filling layer 29 should have acid and alkali resistance and chemical solvent corrosion resistance, have air and water permeability, not easy to deform, and have a certain rigidity and strength; the filling layer 29 can be set or not according to experimental needs.

[0052] A fixing ring can also be provided at the dividing line b of the container 20. Two fixing rings can be provided at the upper and lower ends of the front side of the container 20, and two fixing rings are also provided at the upper and lower ends of the opposite back side. They are mainly used to fix and tightly combine the two sets of bodies constituting the container 20 after the container 20 is fixed, so as to ensure that the container 20 is waterproof and airtight.

[0053] The water tank group 30 is slidably matched with the chute 14 and is provided with a plurality of water chambers 35 surrounding the outer periphery of the container 20 for injecting and storing solutions. The water chambers 35 can be connected with the container 20. The solutions can be solutions of different pH values ​​or different salt ion concentrations and types, and can also be high-strength real filtrate. The specific water tank group 30 adopts a split structure, which includes a plurality of water tanks 31. The plurality of water tanks 31 are respectively located on different sides of the container 20 and are slidably matched with the chute 14. A water chamber 35 is provided in the water tank 31, and a detachable cover plate 36 is provided on the top of the water tank 31. The cover plate 36 is used to seal the water tank 31, and it can be disassembled according to experimental needs. An axially movable inner plate 32 is provided on one side of the water tank 31 relative to the container 20. The inner plate 32 is provided with a communication hole 23, which is connected to the communication hole 23 on the container 20 containing the sample to facilitate the solution to penetrate into the sample. The communication holes 23 on the inner plate 32 can be arranged in 4 rows, with 4 communication holes 23 in each row, so that the solution in the water tank 31 can enter the sample contained in the container 20. Communication holes 23 can also be provided on the other side of the water tank 31 to communicate with the adjacent water tank 31. The inner 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 according to the experimental needs.

[0054] A drain hole 37 and a vent hole 38 that can be switched are also provided on the side of the water tank 31 opposite to the inner plate 32. The drain hole 37 is located at the lower part of the water tank 31. Each water tank 31 can be provided with two drain holes 37 for draining the solution inside the water tank 31. Each water tank 31 can be provided with two vent holes 38. When the vent holes 38 are 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 equipment. A vent line 30a is connected to the vent hole 38 of the water tank 31, and the other end of the vent line is connected to the 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] A water injection hole 39 and at least one temperature sensor 82 are provided on the cover plate 36 of at least one water tank 31, and a detachable sealing plug is provided on the water injection hole 39. The water injection hole 39 can be located on the cover plate 36 of the water tank 31 on the left or right side of the container 20. The temperature sensor 82 can be located on the diagonal line of the cover plate 36 of the water tank 31 on the front or back side of the container 20. The temperature sensor 82 is connected to the control device and can monitor the temperature of the solution in the water tank 31 in real time. At the same time, the temperature sensor 82 must have corresponding waterproof, high temperature and low temperature protection measures to protect it so that it can be used normally in the experiment.

[0056] In the figure, the water tank group 30 is divided into four water tanks 31 according to the four sides of the container 20, and the bottom of the water tank 31 is slidably matched with the chute 14 to fix the positions of the four different water tanks 31. The connection between adjacent water tanks 31 can be used as a disassembly line a to disassemble the water tanks 31. According to experimental needs, when the water tank group 30 is not needed, the water tank 31 can be disassembled according to the specific position of the disassembly line a and slide along the chute 14 to a position away from the experimental operation area 12.

[0057] In practical applications, the iron bracket 11 of the test stand 10 is used to support various parts of the experimental device. It should have corresponding strength and rigidity and have corresponding protection measures to make it resistant to acid, alkali and chemical reagents. The chute 14 around the base of the iron bracket 11 is used to guide the different water tanks 31 to move and position to different positions, and to guide the container 20 and the sample to move to different positions during the shearing process; the chute 14 on the top iron bracket 11 of the test stand 10 is used to guide the multi-directional movement of the pull rod group 15.

[0058] The upper loading assembly 40 can be lifted and lowered on the top of the container 20 to compact the sample in the container 20 or to perform axial loading. The upper loading assembly 40 includes an upper pressing plate 41, an upper telescopic rod 42 and an upper driving member 43; the upper pressing plate 41 is located above the container 20 and is provided with an opening 44, and a detachable cover 45 is provided at the opening 44; the upper telescopic rod 42 is passed through the upper pressing plate 41 and an upper drill bit 46 is provided at the end thereof, and the upper drill bit 46 is located in the opening 44 of the upper pressing plate 41; the upper driving member 43 is installed on the top iron bracket 11 and is connected to drive the upper pressing plate 41 and the upper telescopic rod 42 to rise or fall. The upper driving member 43 is provided with a displacement sensor 81.

[0059] Furthermore, the probe 47 is arranged in the upper pressing plate 41, and a small hole is left on the upper pressing plate 41 for storing the probe 47, and the probe 47 can be extended into the sample. The other end of the probe 47 is connected to the control device, and the control device realizes real-time monitoring of the moisture content inside the sample through relevant auxiliary equipment.

[0060] A dial gauge 48 may also be provided on the upper pressing plate 41 of the upper loading assembly 40, which is fixed and zeroed after being fixed at a corresponding position according to the experimental requirements. When the upper pressing plate 41 moves downward to a preset position, it can be used to test the displacement and deformation of the sample by the amount of pressure or to monitor the consolidation degree 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 member 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 body 45 is provided at the opening 44; the lower telescopic rod 52 is passed through the lower pressure plate 51 and a lower drill bit 54 is provided at the end thereof, and the lower drill bit 54 is located in the opening 44 of the lower pressure plate 51; the lower driving member 53 is connected to drive 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 member 53.

[0062] In the present invention, the upper loading group and the lower loading group are used to apply axial pressure to the sample. The control device controls the hydraulic rod movement of the upper driving member 43 and the lower driving member 53 and monitors the axial deformation of the sample, so as to control the deformation of the sample and apply the magnitude of the axial force. Among them, the telescopic rod and the drill bit are arranged on the upper pressing plate 41 and the lower pressing plate 51, which are mainly used for crack resistance performance experiments, and are used to induce the generation of cracks and the destruction of the sample. The upper drill bit 46 and the lower drill bit 54 are conical, and their size is determined according to the diameter of the disc, and the maximum size does not exceed the size of the opening 44 reserved by the upper pressing plate 41 and the lower pressing plate 51; when the crack resistance performance experiment is not carried out, the circular cone head can be pressed into the upper pressing plate 41 by the telescopic rod and a lid can be covered on the upper part to ensure that the contact between the pressing plate and the sample is flat and unchanged.

[0063] The annular loading assembly 60 is movably disposed in the water tank assembly 30 and can apply radial pressure to the sample. The annular loading assembly 60 includes a plurality of side pressure plates 61 and a plurality of side driving members 62. The plurality of side pressure plates 61 are respectively located in different water chambers 35 of the water tank assembly 30, and the plurality of side driving members 62 are respectively connected to drive the corresponding side pressure plates 61 to move. A displacement sensor 81 is disposed on the side driving member 62.

[0064] In the present invention, a plurality of side pressure plates 61 are respectively located in the water tank 31 on the front, back, left and right sides of the container 20 to apply radial pressure. The pressure is applied by controlling the hydraulic rod of the side driving member 62 through the control device, and the confining pressure can also be applied through the solution in the water cavity 35 of the water tank group 30.

[0065] The shearing assembly 70 is also included. The shearing assembly 70 is movably arranged in the water tank assembly 30 and can shear and destroy the sample. The shearing assembly 70 includes a plurality of shearing plates 71 and a plurality of shearing driving members 72. The plurality of shearing plates 71 are respectively located in different water chambers 35 of the water tank assembly 30. The plurality of shearing driving members 72 are respectively connected to drive the corresponding shearing plates 71 to move. The shearing driving members 72 are provided with a plurality of displacement sensors 81.

[0066] In the present invention, shear top plates are provided in the water tanks 31 located at the front and back of the container 20 as forward shear plates 71, and the shear plates 71 in the water tanks 31 located at the left and right sides of the container 20 serve as oblique shear plates. In the shearing experiment, the second fixing plate 26 on the container 20 is fixed, the first fixing plate 25 is taken out, the movement of the forward shear plate on the front or back is controlled, and a specified direction is selected so that shear failure occurs on the forward shear surface 27. Alternatively, in the experiment of oblique shearing of the specimen, the first fixing plate 25 in the container 20 is fixed, the second fixing plate 26 is loosened or removed, and the movement of the oblique shear plate is controlled so that the specimen is sheared along the oblique shear surface 28. In the experiment, the movement of the hydraulic rod of the shear drive 72 is controlled by the control device and the shear rate is set.

[0067] Furthermore, the device of the present invention is also provided with a rubber sleeve 49 for sealing the joints of different parts of the device to prevent water leakage. Specifically, a rubber sleeve 49 is provided on the outer periphery of the cover plate 36 to seal the junction between the water tank 31 and the cover plate 36. A rubber sleeve 49 is provided at the junction of the hydraulic rod of each driving structure and the water tank 31 to prevent solution leakage and to protect the hydraulic rod from greater resistance during the extension and retraction process.

[0068] The rubber sleeve 49 can also be used as a protective layer to protect the part in contact with the solution in the water tank 31 from corrosion. It has strong elasticity and can be stretched or compressed. It is thin and does not affect the experimental operation. For example, the rubber sleeve 49 can be sleeved on the side pressure plate 61 located in the water cavity 35 of the water tank 31 and the surface of the hydraulic rod located in 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 bottom plate 13 is located above the lower pressing plate 51, and its size is the same as that of the lower pressing plate 51, so that it can move upward with the lower pressing plate 51 when the sample is loaded. In the unconfined compression and shear strength test, the liftable bottom plate 13 is fixed to the surface of the lower pressing plate 51 by bolts 20a. A through slot 16 is provided in the middle of the bottom plate 13, and a detachable sealing sleeve 17 is provided in the slot 16. The size of the slot 16 is slightly larger than the maximum diameter of the lower drill bit 54 in the lower pressing plate 51, so that the lower drill bit 54 in the lower pressing plate 51 can contact and load 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 in the compression and shear strength tests, the sealing sleeve 17 is used to block the slot 16, and the slot 16 is always kept closed during the sample preparation process such as saturation or consolidation of the sample.

[0070] In the present invention, when the container 20 is placed on the bottom plate 13, a sealing rubber layer is provided at the bottom end of the container 20, and a good connection between the sealing rubber layer and the bottom plate 13 is provided to ensure the air tightness (airtightness and watertightness) of the whole device. The bottom plate 13 has a certain thickness, and a plurality of connecting holes 19 are provided in the thickness direction around it. It also includes a plurality of support rods 18, one end of the support rods 18 is detachably connected to the connecting hole 19 of the bottom plate 13, and the other end is detachably connected to the test frame 10 to support the bottom plate 13 when the bottom plate 13 rises to the designed height. At this time, it is necessary to first remove the connection between the bottom plate 13 and the lower pressing plate 51. The lifting and lowering of the bottom plate 13 mainly depends on the drive of the lower pressing plate 51 and the lower driving member 53, and the support rods 18 are used to keep the position unchanged.

[0071] The displacement detection assembly includes a plurality of displacement sensors 81, which are respectively arranged on the upper loading assembly 40, the annular loading assembly 60 and the shearing assembly 70 to detect displacement information. The control device is connected to the upper loading assembly 40, the lower loading assembly 50, the annular loading assembly 60, the shearing assembly 70 and the displacement detection assembly to control the operation of each assembly and obtain displacement information.

[0072] The driving structure of the upper loading assembly 40, the lower loading assembly 50, the annular loading assembly 60, and the shearing assembly 70 of the present invention can adopt a hydraulic cylinder, the hydraulic cylinder is provided with a hydraulic rod, each hydraulic rod is provided with a displacement sensor 81 to detect displacement information, and the control device is connected to each displacement sensor 81, and is used to monitor the deformation (axial and radial) of the sample and the displacement of the hydraulic rod in real time, so as to judge whether the sample is damaged and stop the experiment. The auxiliary equipment in the present invention includes a vacuum pump, a blast dryer, a small portable refrigerator, etc.

[0073] Before testing the device of the present invention, the following operations need to be performed:

[0074] 1) The water tank group 30 is disassembled into four water tanks 31 along the disassembly and assembly line a, and the position of the water tank 31 is fixed by the slide 14, so that the water tank 31 is away from the center on the bottom plate 13, and the hydraulic rod in the water tank 31 changes with the change of its position.

[0075] 2) Ensure that the first fixing plate 25 and the second fixing plate 26 on the container 20 remain unchanged, insert the sealing layer 33 downward into the container 20, and set the filling layer 29 according to the experimental needs to control the shape of the sample. Divide the container 20 into two sets along the dividing line b, connect the connecting plates 24 of the two sets to the tie rod group 15 respectively, and control the tie rod group 15 through the control device to move the two sets along the slide groove 14 and splice with the bottom plate 13. After the container 20 is aligned and assembled, fix the fixing plate 22 on the dividing line b to ensure that the container 20 is a complete whole.

[0076] 3) Control the lower pressing plate 51 of the lower loading assembly 50 to move so that it is flush with the upper end of the slide groove 14 on the bottom iron bracket 11. And control the telescopic rod in the lower pressing plate 51 so that the lower drill bit 54 does not push out (i.e., the surface of the lower pressing plate 51 is flat); similarly, control the telescopic rod in the upper pressing plate 41 so that the upper drill bit 46 does not push out (i.e., the surface of the upper pressing plate 41 is flat).

[0077] The probe 47 on the upper pressing plate 41 can be set or not according to the experimental requirements. When setting, the probe 47 is inserted into the sample through the small hole of the upper pressing plate 41, and the changes in the moisture content and humidity inside the sample are observed in real time through auxiliary equipment; if the setting is not considered, the probe 47 is taken out and the small hole on the upper pressing plate 41 is closed.

[0078] 4) The required moisture content, dry density and compaction degree of the sample are calculated according to the experimental requirements, and the prepared material is poured into the container 20. The control device controls the upper pressing plate 41 to descend to compact the sample.

[0079] Based on the above steps, the unconfined compressive strength test is carried out using the device of the present invention:

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

[0081] a2 Connect the tie rod assembly 15 to the container 20, remove the fixing plate 22 on the surface of the container 20, separate the container 20 into two sets (this process needs to be separated slowly to avoid damaging the sample), and control the tie 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 pressing plate 51, and the position of the sample can be adjusted to the appropriate position required by the experiment through the action of the lower pressing plate 51 of the lower loading assembly 50.

[0082] a3 controls the upper pressing plate 41 to move slowly downward to perform the loading test, and turns on the switch of the displacement sensor 81 on the hydraulic rod in advance before the experiment to detect and control the displacement of the sample.

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

[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 (it is generally believed that the sample is damaged when the axial deformation is between 15% and 20%). The sample is considered to be fully damaged.

[0085] a5 After the sample is destroyed, the upper pressing plate 41 is controlled to stop moving downward and rise to return to the initial state, thus ending the experiment.

[0086] The axial stress and axial strain of the sample can be read and recorded and stored through the displacement sensor 81 and the relevant data collector, and the magnitude of the axial force of the sample during the experiment can be monitored in real time through the control device.

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

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

[0089] Where (1): ε is the axial strain, unit: %; Δh is the axial strain, h0 is the initial height of the specimen, unit: mm;

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

[0091] In formula (2): A a The cross-sectional area of ​​the sample after correction, A0 is the initial area of ​​the sample before correction, in cm 2 ;

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

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

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

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

[0096] The steps in the confined compressive strength test are similar to those in the unconfined compressive strength test, except that:

[0097] In hydraulic sample preparation, after the sample is fully solidified, the upper pressure plate 41 is not moved, so that it contacts the sample surface but does not apply axial pressure; the notch 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 arranged around the sealing sleeve 17 to ensure the good air tightness of the device and prevent the sample from leaking.

[0098] The container 20 is not removed and only the fixing sheet on the surface of the container 20 is removed, so that during subsequent loading, the container 20 can move to amplify the deformation of the sample. At the same time, the connection between the tie rod assembly 15 and the container 20 is released.

[0099] Move the inner side plates 32 of the four water tanks 31 upward to a suitable position and fix them, so that the side pressure plates 61 in the water tanks 31 can extend out of the water tanks 31; control the side pressure plates 61 of the annular loading assembly 60 to move to the four surfaces of the container 20, and apply a certain confining pressure to the sample in the container 20 according to experimental requirements.

[0100] Steps a3-a5 remain unchanged, but during this loading process, the dial gauge 48 is not needed to monitor and control the deformation of the specimen, and all real-time monitoring is performed using the displacement sensor 81 on the hydraulic rod.

[0101] The confined compressive strength is directly obtained according to the corresponding data obtained by the control device to obtain the compressive strength of the sample under different confining pressures.

[0102] Cracking strength test operation

[0103] In the cracking 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, and at this time, the upper pressure plate 41 should be away from the upper surface of the sample, that is, the sample is not subjected to axial load.

[0104] b1 After connecting the connecting holes 19 around the bottom plate 13 and controlling the lower pressing plate 51 to rise to the designed height, the supporting rods 18 around the bottom plate 13 are fixed on the test frame 10 to support the bottom plate 13 and the specimen. The notch 16 of the bottom plate 13 is opened to facilitate the lower drill bit 54 on the lower pressing plate 51 to contact the specimen and apply load.

[0105] b2 controls the lower pressing plate 51 to move downward and away from the bottom plate 13. The distance of separation needs to ensure that the probe in the lower pressing plate 51 can be smoothly extended without touching the sample (damaging the sample). Therefore, before preparing the sample for the cracking strength test, the bolts fixing the bottom plate 13 and the lower pressing plate 51 need to be unscrewed in advance to ensure that the bottom plate 13 and the lower pressing plate 51 can be separated smoothly.

[0106] b3 Open the slots 16 on the upper pressing plate 41 and the lower pressing plate 51, and let the upper drill bit 46 and the lower drill bit 54 slowly extend from the upper pressing plate 41 and the lower pressing 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 replaced in advance.

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

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

[0110] b5 controls the upper pressing plate 41 and the lower pressing plate 51 with the drill bit extended therefrom to move relative to each other at the same time. The two move at the same speed to load the sample. At the same time, the displacement, stress, strain and ultimate load size of the sample are monitored. The development of cracks on the surface of the sample during the experiment can also be recorded until the sample is destroyed.

[0111] See also Fig.14 During the loading process, when the displacement of the lower drill bit 54 in the lower pressing plate 51 exceeds the height reserved for the bottom plate 13 before the experiment and the sample has not reached the ultimate load and is damaged, the bottom plate 13 will move upward together with the lower pressing plate 51 until the sample is damaged.

[0112] The cracking strength of the sample is calculated according to the following formula:

[0113]

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

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

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

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

[0118] Shear strength test operation steps

[0119] Before the shear test, the specific experimental steps are the same as the above steps 1)-4). According to the experimental needs, 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 of the joint of the device is ensured (airtight and watertight); during the shearing process, the connection between the tie rod group 15 and the container 20 is disconnected.

[0120] Before the shearing process of the sample, first ensure that the shear top plate is in contact with the surface of the container 20. At this time, first move the inner plate 32 of the water tank 31 upward to a suitable position and fix it unchanged to ensure that the shear top plate can be moved to the surface of the container 20. The shear in the test is divided into unconsolidated undrained, consolidated undrained and consolidated drained shear tests.

[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 pressing plate 41 is controlled by the control device to directly perform shear failure while applying a corresponding axial load on the sample surface.

[0122] If consolidation without drainage shearing is performed, the upper pressing plate 41 is controlled to apply consolidation pressure to the sample, so that it is fully consolidated under this consolidation pressure. At this time, the sealing layer 33 is moved up to the corresponding position and fixed to ensure that the material is fully consolidated before shearing. When the sample is fully consolidated, the sealing layer 33 is moved down and fixed in the container 20 to be sheared and damaged. During this process, the moisture in the sample is not allowed to be discharged.

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

[0124] During the consolidation process, the axial deformation of the sample is monitored by a dial gauge 48 and related parameters such as the compression coefficient, compression modulus, rebound modulus, and porosity of the soil sample are calculated.

[0125] After the consolidation process of the sample is completed and before the shear test begins, select the appropriate shear direction of the sample to perform shear failure on it; if the sample needs to be destroyed along the positive shear plane 27, open the first fixing plate 25 and tighten the second fixing plate 26; if the sample needs to be destroyed along the oblique shear plane 28, open the second fixing plate 26 and tighten the first fixing plate 25.

[0126] When consolidation is completed, the required shear direction is selected according to the experimental needs, and the shear top plate is controlled by the control device to perform shear tests on the sample under various loads. The displacement, stress and strain of the sample during the shear process are monitored by the information detected by the displacement sensor 81 on the shear assembly 70, and the ultimate load that the sample bears when shear failure occurs is obtained in combination with the remote end of the control device.

[0127] The shear strength of the sample is calculated according to the following formula:

[0128] W=Px Formula (6)

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

[0130] The shear strength index of the sample is calculated according to the following formula:

[0131]

[0132] In formula (7), σ is the normal stress, unit is kPa, is the internal friction angle, unit (°), c is the cohesion of the soil, unit kPa.

[0133] Saturation test procedure of the sample

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

[0135] c1 According to step 1) to step 4), the prepared sample in the container 20 is placed and kept still, and the upper pressing plate 41 is connected to the top surface of the sample, and the connection between the container 20 and the tie rod group 15 is removed; and check whether the sealing performance of the device is good.

[0136] Check whether the air tightness of the water tank 31 is good, cover the upper part of the water tank 31 with the cover plate 36 and ensure good air tightness, and fix the inner plate 32 on the water tank 31; close the drainage hole 37 at the bottom of the water tank 31 and the vent hole 38 at the upper part.

[0137] c2 Control the side pressure plates 61 on the front, the back, and the left and right sides to slowly contact the partitions of the water tanks 31, and then drive the four water tanks 31 to move toward the container 20 through the movement of the side pressure plates 61 to make them closely contact with the container 20. Stop the movement, and drive the side pressure plates 61 to retract so as not to block the connecting holes 23 on the inner side plates 32; check whether the connecting holes 23 of adjacent water tanks 31 are aligned, and check again whether the air tightness of the device is good.

[0138] c3 Before filling water into the water tank 31, 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 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 experimental needs).

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

[0140] c5 After the control device controls the hydraulic rod to drive the side pressure plate 61 to slowly contact the outer side of the water tank 31, the control device continues to move the surrounding water tanks 31 away from the container 20 to completely separate 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 operation mentioned above; the confined compressive strength test of the saturated specimen can be completed by combining the confined compressive strength test operation steps; the cracking strength test of the saturated specimen can be completed by combining the cracking strength test operation steps; and the shear strength test of the saturated specimen can be completed by combining the shear strength test operation steps.

[0142] Dry-wet or freeze-thaw cycle test process steps of the sample

[0143] Before the sample is subjected to the dry-wet cycle operation, the container 20 containing the sample is installed and fixed according to steps 1)-4); according to the above steps c1-c2, the water tank 31 is moved to the outer surface of the container 20 and is in close contact with it.

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

[0145] d 2 After the sealing layer 33 is pulled out of the container 20, a rubber sleeve 49 is put on the junction between the upper pressing plate 41 and the container 20 and the surface of the container 20 in an annular direction to ensure the airtightness of the device.

[0146] d 3 Open the vent hole 38 (laterally), and control the vent hole 38 (laterally) through the control device to blow dry the sample with an external blower dryer, and the hot air enters the sample through the connecting 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 moisture content change of the sample can be monitored by the probe 47 on the upper pressing plate 41, and the drying state can be controlled in combination with the moisture content of the sample.

[0147] d 4 After the test drying is completed, close the vent hole 38 (upper part) and the power supply of the blower dryer; exhaust the sample in the experiment through the vent hole 38 and its external exhaust pump, and close the vent hole 38 (upper part) after the exhaust is completed.

[0148] d 5 Then, a solution (the solution is designed according to needs) 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 drainage hole 37.

[0149] The steps in the freeze-thaw cycle are basically the same as the above-mentioned wet-dry cycle operation, with only a slight change in step d3: during the freezing process, the cover 36 is opened and a small portable refrigerator is placed in the water tank 31, and then the cover 36 is re-sealed with the water tank 31.

[0150] Through the vent hole 38 (laterally) cooperate with the blast drying box, at this time the blast index is set to about 0°C). Turn on the refrigerator and blow cold air into the sample through the connecting hole 23 in combination with the vent hole 38 to complete the freezing process. During this process, the temperature can be monitored by 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 the vacuum pump to evacuate air is omitted.

[0151] The above steps are a single dry-wet or freeze-thaw cycle process, and different dry-wet or freeze-thaw cycle times can be set according to experimental needs; and the test of relevant mechanical properties can be completed according to step c6.

[0152] The tester of the present invention combines the compression resistance, crack resistance and shear strength that are the main concerns of current soil research into one, realizes the unification of relevant mechanical property tests of materials under dry-wet or freeze-thaw cycle effects or simulation of different complex environmental conditions and simplifies related work.

[0153] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A mechanical properties tester for soil under dry-wet or freeze-thaw cycle effects, characterized in that: The invention comprises a test stand, a container, a water tank group, an upper loading component, a lower loading component, a circumferential loading component, a shearing component, a displacement detection component and a control device; an experimental operation area is arranged in the test stand, and a movable bottom plate and a plurality of slide grooves are arranged on the bottom surface of the experimental operation area, and the slide grooves are located on the periphery of the bottom plate and extend along the first direction or the second direction; the container is connected from top to bottom, and the bottom and the bottom plate are detachably sealed to place the sample; the water tank group and the slide groove are slidably matched and are provided with a plurality of water cavities surrounding the periphery of the container for injecting solution, and the water cavities can be connected to the container; the upper loading component can be lifted and lowered on the top of the container to perform displacement detection on the sample in the container The sample is compacted or axially loaded; the lower loading component is detachably connected to the bottom plate and can be raised and lowered to adjust the axial position of the sample; the annular loading component is movably arranged in the water tank group and can apply radial pressure to the sample; the shearing component is movably arranged in the water tank group and can shear the sample; the displacement detection component includes a plurality of displacement sensors, which are respectively arranged on the upper loading component, the annular loading component and the shearing component to detect displacement information; the control device is connected to the upper loading component, the lower loading component, the annular loading component, the shearing component and the displacement detection component.

2. A mechanical properties tester for soil under dry-wet or freeze-thaw cycle effects as claimed in claim 1, characterized in that: The container includes two shells; the two shells are symmetrically arranged and detachably connected, the bottom of the shell is sealed with the bottom plate, and the side of the shell is provided with a plurality of connecting holes and a plurality of connecting plates; two retractable pull rod groups are arranged in the test frame, and the two pull rod groups are detachably connected to the connecting plates on the two shells; the control device is connected to the pull rod group to control its movement to drive the two sleeves to move along the slide groove to realize disassembly and assembly.

3. A mechanical properties tester for soil under dry-wet or freeze-thaw cycle effects as claimed in claim 1, characterized in that: The side of the container is provided with a plurality of detachable first fixing plates and a plurality of detachable second fixing plates, wherein the plurality of first fixing plates are distributed at intervals along the first direction or the second direction of the test frame; and the plurality of second fixing plates are distributed at intervals along the diagonal line of the side of the container.

4. A mechanical properties tester for soil under dry-wet or freeze-thaw cycle effects as claimed in claim 3, characterized in that: It also includes a plurality of sealing layers, which can be axially inserted into the inner side of the water cavity to close the connecting hole to facilitate non-drainage shearing, and a breathable and water-permeable layer can be arranged between the sealing layer and the inner wall of the water cavity; or a filling layer is also arranged in the container, and the filling layer fills the gap between the sample and the inner side of the water cavity to control the shape of the sample.

5. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 1, characterized in that: The water tank group includes a plurality of water tanks, which are respectively located on different sides of the container and slidingly cooperate with the slide groove; the water cavity is arranged in the water tank, a removable cover plate is arranged on the top of the water tank, an axially movable inner plate is arranged on the side of the water tank opposite to the container, the inner plate is provided with the connecting hole, and a switchable drainage hole and a switchable ventilation hole are also arranged on the side of the water tank opposite to the inner plate; a water injection hole and a temperature sensor are arranged on the cover plate of at least one of the water tanks, and a removable sealing plug is arranged on the water injection hole.

6. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 4, characterized in that: The bottom plate is provided with a through slot in the middle, and a detachable sealing sleeve is provided in the slot; a plurality of support rods are also provided, one end of each support rod is detachably connected to the bottom plate, and the other end is detachably connected to the test stand to support the bottom plate when the bottom plate rises to a designed height.

7. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 1, characterized in that: The upper loading assembly includes an upper pressure plate, an upper telescopic rod and an upper driving member; the upper pressure plate is located above the container and is provided with an opening, a detachable cover is provided at the opening, and a detachable probe is also provided on the upper pressure plate to insert the sample to detect the moisture content or humidity; the upper telescopic rod is passed through the upper pressure plate and an upper drill bit is provided at the end, and the upper drill bit is located in the opening of the upper pressure plate; the upper driving member is connected to drive the upper pressure plate and the upper telescopic rod to rise or fall, and the upper driving member is provided with the displacement sensor.

8. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 1, characterized in that: The lower loading assembly includes a lower pressure plate, a lower telescopic rod and a lower driving member; the lower pressure plate is detachably connected to the base plate and is provided with an opening, and a detachable cover is provided at the opening; the lower telescopic rod is passed through the lower pressure plate and a lower drill bit is provided at the end thereof, and the lower drill bit is located in the opening of the lower pressure plate; the lower driving member is connected to drive the lower pressure plate and the lower telescopic rod to rise or fall, and the lower driving member is provided with the displacement sensor.

9. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 1, characterized in that: The annular loading assembly includes a plurality of side pressure plates and a plurality of side driving members, wherein the plurality of side pressure plates are respectively located in different water chambers of the water tank group, and the plurality of side driving members are respectively connected to drive the corresponding side pressure plates to move, and the side driving members are provided with the displacement sensors.

10. The mechanical properties tester of soil under dry-wet or freeze-thaw cycle effect as claimed in claim 1, characterized in that: The shearing assembly includes a plurality of shearing plates and a plurality of shearing driving members, wherein the plurality of shearing plates are respectively located in different water chambers of the water tank group, and the plurality of shearing driving members are respectively connected to drive the corresponding shearing plates to move, and the shearing driving members are provided with a plurality of displacement sensors.

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