Self-fed high-temperature unsaturated frozen soil interface shear test device and method thereof

Abstract

The invention provides a self-fed high-temperature unsaturated frozen soil interface shear test device and a method thereof, and relates to the technical field of civil engineering tests. The test device comprises a shell assembly, a torsion loading assembly, a gas phase imbedding assembly, a liquid phase imbedding assembly, a soil sample containing assembly and a self-feedback assembly, the torsion loading assembly comprises a torsion control box arranged on the inner side of a bottom box, and a torsion controller, a data acquisition master controller and a torsion device are arranged in the torsion control box; the output end of the torsion device is fixedly connected with a hollow cylinder through a torsion transmission shaft, and the hollow cylinder is detachably connected with a plurality of shearing plates. Through the arrangement of the gas phase imbedding assembly, the liquid phase imbedding assembly and the self-feedback assembly, the shearing characteristics of the unsaturated high-temperature frozen soil and the pile interface can be studied under the conditions of different matrix suction forces, different overlying loads and different freezing temperatures by utilizing self-regulation and feedback of the self-feedback assembly.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering tests, and specifically to a self-feed type high-temperature unsaturated frozen soil interface shear test device and method thereof. Background Art

[0002] Unsaturated frozen soil is a porous multiphase medium composed of solid soil particles, unfrozen water, ice crystals and pore gas. Among them, the content of gas phase and liquid phase will affect the matrix suction of unsaturated frozen soil, and thus will affect the shear force of the unsaturated frozen soil interface. The existence of unsaturated frozen soil will have an important impact on the stability and safety of engineering structures. Therefore, studying the mechanical properties of unsaturated frozen soil and its relationship with the pile-soil interface interaction has important theoretical significance and practical application value.

[0003] In related technologies, such as a frozen soil tension-shear integrated tester with the publication number: CN112611638B, which includes a horizontal loading device, a vertical loading device, a pulling fixture and a shear fixture. This patent measures the shear force by applying forces in the horizontal and vertical directions.

[0004] Another example is a creep test method for a pile-frozen soil shear specimen with the publication number: CN115876579A, which includes a material testing machine, a constant temperature box and a pile-frozen soil shear specimen mold with controllable normal stress placed in the constant temperature box. This patent conducts a creep test by applying a force in the vertical direction.

[0005] Another example is an intelligent self-rotating hollow cylinder interface shear instrument and its testing method with the publication number: CN113640213B. This patent can test the interface friction of different geotechnical bodies under complex stress conditions, but still does not meet the test requirements of the unsaturated frozen soil interface.

[0006] Most of the existing frozen soil test devices lack self-regulation and feedback capabilities, and it is difficult to adapt to the characteristics of wide distribution and complex environment of unsaturated frozen soil; it is impossible to accurately understand the characteristics of the pile-soil interface shear at the interface between unsaturated frozen soil and thawed soil. Therefore, a self-feed type high-temperature unsaturated frozen soil interface shear test device is urgently needed to be developed. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides a self-feed type high-temperature unsaturated frozen soil interface shear test device and method thereof, which solves the problems that the existing frozen soil test devices lack self-regulation and feedback capabilities; and it is impossible to accurately understand the characteristics of the pile-soil interface shear at the interface between unsaturated frozen soil and thawed soil.

[0008] To achieve the above objectives, the present invention is realized through the following technical solutions: A self-feed type high-temperature unsaturated frozen soil interface shear test device, including; A housing assembly, which sequentially includes a bottom box, a reaction support wall, and a detachable upper cover from bottom to top; A torsion loading assembly, which is arranged inside the housing assembly and is used to apply torsion to the soil sample; the torsion loading assembly includes a torsion control box arranged inside the bottom box, and a torsion controller, a data acquisition master controller, and a torsion device are arranged inside the torsion control box. The output end of the torsion device is fixedly connected with a hollow cylinder through a torsion transmission shaft. A plurality of shear plates are detachably connected to the hollow cylinder. A torsion application fixing buckle is detachably connected to the upper part of the hollow cylinder. A plurality of temperature sensors are installed on the circumferential surface of the hollow cylinder; A matrix suction control system, which includes a gas phase injection component and a liquid phase injection component. The gas phase injection component is arranged at the top of the reaction support wall and is used to inject gas into the soil sample; The liquid phase injection component is arranged on the hollow cylinder and is used to inject liquid into the soil sample; the liquid phase injection component includes a water inlet device and a water equalizing component. The water equalizing component is arranged on the hollow cylinder. The water equalizing component includes a flushing pipeline. The water outlet end of the water inlet device is communicated with the flushing pipeline. Control valves and ceramic plates are alternately arranged on the flushing pipeline. An S-shaped cavity is arranged inside the ceramic plate; The gas phase injection component includes an air inlet device. The air outlet end of the air inlet device is communicated with the flushing pipeline through a pipeline; A soil sample accommodation component, which is arranged inside the reaction support wall and is used to hold the soil sample; the soil sample accommodation component includes a soil sample loading bottom plate fixedly installed on the bottom box. A rubber membrane is fixedly connected concentrically on the soil sample loading bottom plate. The torsion transmission shaft passes through the soil sample loading bottom plate and is in rotational fit with each other. A soil sample cavity is formed between the rubber membrane and the hollow cylinder. A pressure cavity is formed between the rubber membrane and the reaction support wall; A self-feeding component, which is used to automatically control the amount of antifreeze injected into the pressure cavity according to the difference between the volume change pressure value of the pressure cavity and the standard pressure value. By setting the gas phase injection component, the liquid phase injection component, and the self-feeding component, and using the self-regulation and feedback of the self-feeding component, the shear characteristics of the interface between unsaturated high-temperature frozen soil and piles can be studied under different matrix suctions, different overburden loads, and different freezing temperatures.

[0009] Preferably, the bottom box is fixedly connected with the reaction support wall. The reaction support wall is tubular. An upper load part is arranged at the center of the upper cover. The upper load part is in contact with the torsion application fixing buckle.

[0010] Preferably, a needle and / or a blade for embedding into the soil sample are / is fixedly connected to the lower surface of the torsion application fixing buckle. A clamping part is arranged on the shear plate. The clamping part is clamped with the hollow cylinder.

[0011] Preferably, the self-feed component includes a liquid pumping device, a standard pressure feedback device, a pressure controller, a water level balancer, and a volume change test sensor. The volume change test sensor, the pressure controller, the liquid pumping device, and the standard pressure feedback device are all arranged in the bottom box, and the water level balancer is arranged outside the reaction support wall. The volume change test sensor is used to monitor the pressure value in the pressure chamber. The liquid pumping device is used to pump the antifreeze liquid at the target temperature into or out of the pressure chamber. The standard pressure feedback device is used to calculate the difference between the pressure value in the pressure chamber and the standard value. The pressure controller is used to control the operation of the liquid pumping device according to the difference.

[0012] Preferably, it further includes a computer, which is electrically connected to the standard pressure feedback device, the pressure controller, the water level balancer, the temperature sensor, the volume change test sensor, the torque device, the torque controller, and the data acquisition master controller. The computer is used for setting the test scheme and collecting and analyzing the test data.

[0013] The present invention also provides a self-feed high-temperature unsaturated frozen soil interface shear test method, which uses the above-mentioned self-feed high-temperature unsaturated frozen soil interface shear test device, and includes the following steps: Step 1: Test preparation; comprehensively check the overall device to ensure the airtightness of the overall device, the good condition of the sensors, and discharge the air in all the pipelines of the device. Select a shear plate with an appropriate friction coefficient according to the properties of the soil sample. Step 2: Place the soil sample; place the soil sample into the soil sample chamber. Step 3: Saturate and consolidate the soil sample; start the gas phase placement component and the liquid phase placement component, and use backpressure saturation combined with relevant saturation methods to saturate the soil sample to meet the saturation requirements of the test. Step 4: Shear test, start the self-feed component and the torque loading component, pump the antifreeze liquid at the target temperature into the pressure chamber, so that the soil sample is driven by torque under the action of the preset hydraulic pressure and temperature, and record the test data.

[0014] The present invention provides a self-feed high-temperature unsaturated frozen soil interface shear test device and method, which have the following beneficial effects: Through the gas phase placement component, the liquid phase placement component, and the self-feed component provided by the present invention, and by using the self-regulation and feedback of the self-feed component, the shear characteristics of the interface between unsaturated high-temperature frozen soil and pile can be studied under different matrix suction, different overburden loads, and different freezing temperatures.

[0015] Through the torque loading component provided by the present invention, the total volume change test of the soil sample is completed by simulating the frictional force at the interface of different rock and soil masses. Description of the Drawings

[0016] Figure 1Schematic structural diagram of the present invention; Figure 2 Stereogram of the hollow cylinder part of the present invention; Figure 3 Stereogram of the hollow cylinder and temperature sensor of the present invention; Figure 4 Stereogram of the water inlet device and water equalizing component of the present invention; Figure 5 Stereogram of the water equalizing component of the present invention; Figure 6 Cross-sectional view of the clay board of the present invention; Figure 7 Stereogram of the shear plate of the present invention.

[0017] Wherein, 1, soil sample chamber; 2, hollow cylinder; 3, torsion application fixing buckle; 5, temperature sensor; 6, pressure chamber; 7, rubber membrane; 8, air inlet device; 9, water inlet device; 10, volume change test sensor; 11, torsion transmission shaft; 12, torsion controller and data acquisition general controller; 13, shear plate; 1301, engaging part; 14, reaction support wall; 1401, bottom box; 1402, upper cover; 15, torsion control box; 16, liquid pumping device; 17, soil sample loading bottom plate; 18, standard pressure feedback device; 19, pressure controller; 20, computer; 21, water level balancer; 22, water equalizing component; 2201, flushing pipeline; 2202, control valve; 2203, clay board; 31, S-shaped chamber. Specific embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] As Figures 1-7 shown, the embodiment of the present invention provides a self-feed type high-temperature unsaturated frozen soil interface shear test device, including; A housing assembly, which successively includes a bottom box 1401, a reaction support wall 14, and a detachable upper cover 1402 from bottom to top; Referring to Figure 1 , the bottom box 1401 is mainly used to provide protection for internal components, and the reaction support wall 14 is used to provide a supporting force for the antifreeze liquid in the pressure chamber 6.

[0020] The bottom box 1401 is fixedly connected to the reaction support wall 14. The reaction support wall 14 is tubular, and an upper load part is provided at the center of the upper cover 1402, and the upper load part is in contact with the torsion application fixing buckle 3; Reference Figure 1 , the tubular reaction support wall 14 is used to form the supporting force of the circumferential surface and adapt to the shape of the pressure chamber 6; the upper load part is used to provide the upper load force for the soil sample. The self-weight of the upper cover 1402 can be utilized, or a load device for providing load can be used to achieve this. Whether to use the load device can be selected according to the actual test requirements. Here, the load device can be a hydraulic device.

[0021] The torsion loading assembly is arranged inside the housing assembly and is used to apply torsion to the soil sample; the torsion loading assembly includes a torsion control box 15 arranged inside the bottom box 1401. A torsion controller, a data acquisition master controller 12, and a torsion device are arranged inside the torsion control box 15. The output end of the torsion device is fixedly connected with a hollow cylinder 2 through a torsion transmission shaft 11. A plurality of shear plates 13 are detachably connected to the hollow cylinder 2. A torsion application fixing buckle 3 is detachably connected to the upper part of the hollow cylinder 2. A plurality of temperature sensors 5 are installed on the circumferential surface of the hollow cylinder 2; Reference Figure 1 , the torsion control box 15 is used to provide protection for the internal components; the torsion controller and the data acquisition master controller 12 are used to control the torsion output value of the torsion device, collect the torsion data, and transmit this data to the computer 20 for reflecting the value of the shear force; this torsion is transmitted to the soil sample through the torsion transmission shaft 11, the hollow cylinder 2, and the shear plates 13; among them, the shear plates 13 can be detached from the hollow cylinder 2. Therefore, shear plates 13 with different friction coefficients can be selected to simulate the interface friction of different rock and soil bodies by using the shear plates 13 to complete the test of the total volume change of the soil sample; among them, the temperature sensors 5 are used to monitor the temperature of each part of the soil sample to determine whether the soil sample is tested at the preset temperature value; In temperature control, the temperature sensors 5 real-time feedback the temperature values of each part of the soil sample. According to the tested soil sample, the basic parameters of the corresponding soil sample, such as the density, water content, and specific gravity of the soil sample, are input into the corresponding liquid pumping system of the pressure controller 19. After setting, the system pumps the antifreeze content suitable for the temperature of the soil sample into the pressure chamber 6 through the liquid pumping device 16 to reach the set temperature value within a predetermined time, and the entire temperature control accuracy reaches ±0.1 degree Celsius, and this temperature control standard is achieved during the shearing process, improving the temperature control standard in the test. Compared with the existing temperature control system with a temperature control range of ±1.0 °C, the temperature control accuracy is higher. For specific data, see: Temperature Control Test Data Table;

[0022] The lower surface of the torsion application fixing buckle 3 is fixedly connected with a needle and / or blade for embedding into the soil sample. The shear plate 13 is provided with a clamping part 1301, and the clamping part 1301 is clamped with the hollow cylinder 2; Reference Figure 1, the needle and / or blade on the torque-applying fixed buckle 3 is used to insert into the soil sample, increasing the contact area between the soil sample and the torque-applying fixed buckle 3, and preventing the soil sample from sliding relative to the torque-applying fixed buckle 3 when torque is applied.

[0023] The matric suction control system, which includes a gas-phase injection component and a liquid-phase injection component. The gas-phase injection component is arranged at the top of the reaction force support wall 14 and is used to introduce gas into the soil sample; The gas-phase injection component includes an air inlet device 8, and the outlet end of the air inlet device 8 is interconnected with the flushing pipeline 2201 through a pipeline; Reference Figure 1 , the air inlet device 8 can be an air pump, which is used to generate gas and introduce the gas into the flushing pipeline 2201. In order to avoid gas leakage, it should be used in conjunction with a valve. In the S-shaped cavity 31, the gas phase and the liquid phase are fully mixed and evenly enter the soil sample, increasing the gas-phase and liquid-phase components in the soil sample.

[0024] The liquid-phase injection component is arranged on the hollow cylinder 2 and is used to introduce liquid into the soil sample; For the control of matric suction, by using the mutual cooperation of the ceramic plate 2203, the air inlet device 8, the pipeline and the liquid-phase injection component, the segmented control of matric suction is realized, resulting in a significant shortening of the matric suction stabilization time of the entire specimen. The time is shortened by more than 75%, saving the cost in the test. For specific data, see the table of matric suction stabilization time and stabilization effect;

[0025] Note: The stabilization time is calculated using the desiccation method. Real-time moisture content testing (volumetric water content) is carried out according to the model test Teros12, and the above data is obtained through comparative analysis in combination with the test effect of the pressure plate. The stabilization time is obtained by testing the water output using the pressure plate after the specimen is prepared by the ring knife method with equal thickness. The fluctuation value after stabilization is obtained by testing with a tensiometer. Since the measurement range of the tensiometer is 0 - 100 kPa, there is no data after exceeding 100 kPa. The inventor of this technology has conducted similar indoor tests. Currently, all existing equipment intakes air from the top of the specimen and controls the pore water pressure at the bottom. The matric suction equilibrium time (the minimum height of the triaxial test is 76 mm) takes about 30 - 45 days. When the specimen thickness becomes 20 mm, the matric suction equilibrium path is shortened by 75%, and the time is about 7 - 10 days, with the time shortened by more than 75%. The test is for silty clay.

[0026] The liquid-phase injection component includes a water inlet device 9 and a water distribution component 22. The water distribution component 22 is arranged on the hollow cylinder 2. The water distribution component 22 includes a flushing pipeline 2201. The outlet end of the water inlet device 9 is interconnected with the flushing pipeline 2201. The flushing pipeline 2201 is alternately provided with a control valve 2202 and a ceramic plate 2203. The ceramic plate 2203 is provided with an S-shaped cavity 31; Reference Figure 1 、 Figure 2 、 Figure 4 、 Figure 5 、 Figure 6 , The water inlet device 9 can be a pump body for introducing liquid into the soil sample to increase the liquid phase component in the soil sample, and finally obtain unsaturated frozen soil with a preset value. By controlling the component amounts of the liquid phase and the gas phase, unsaturated frozen soil with different components can be formed; the liquid pumped into the flushing pipeline 2201 by the water inlet device 9 can be controlled by the control valve 2202 to enter each clay board 2203 or not. For example, if the control valve 2202 at the uppermost side is opened and the other control valves 2202 are closed, then the liquid and gas can only enter the uppermost clay board 2203, so that the positions of water inlet and gas inlet can be controlled; Among them, in the initial state, the S-shaped cavity 31 can fully discharge the air in the flushing pipeline 2201, avoiding the influence of the air in the flushing pipeline 2201 on the gas phase component amount of the unsaturated frozen soil. And the water flow in the S-shaped cavity 31 will generate pressure at the bending part, making the water flow more easily enter the micropores in the clay board 2203, improving the efficiency of adding water to the soil sample; the bending part of the S-shaped cavity 31 can form a more complex microscopic pore network, promoting the adsorption and penetration of the water phase and the gas phase, increasing the rising height of the capillary effect, and dispersing the water flow to a higher position of the clay board 2203; the water evaporation rate at the bending part of the S-shaped cavity 31 is less than that at the non-bending part. Therefore, during the temperature transfer process, the heat is dispersed more evenly by using the heat transfer during water evaporation, reducing the test error of the unsaturated frozen soil at different temperatures; since the test temperature change value range of the unsaturated frozen soil is relatively large, the low temperature state can be minus twenty degrees and the high temperature state can be one degree. The structure of the S-shaped cavity 31 can reduce the cracking risk of the clay board 2203 during the water absorption - water loss cycle at different temperatures by dispersing stress, thus maintaining the stability of the water absorption performance and being more suitable for the test requirements of high temperature unsaturated frozen soil.

[0027] The outer cylindrical surface of the clay board 2203 is flush with the outer cylindrical surface of the hollow cylinder 2, ensuring that the clay board 2203 can contact the soil sample, introduce moisture into the soil sample, and meet the conditions for torque application.

[0028] The soil sample accommodating assembly is arranged inside the reaction support wall 14 for accommodating the soil sample; the soil sample accommodating assembly includes a soil sample loading bottom plate 17 fixedly installed on the bottom box 1401. A rubber membrane 7 is fixedly connected concentrically on the soil sample loading bottom plate 17. The torque transmission shaft 11 passes through the soil sample loading bottom plate 17 and is in rotational fit with each other. A soil sample cavity 1 is formed between the rubber membrane 7 and the hollow cylinder 2, and a pressure cavity 6 is formed between the rubber membrane 7 and the reaction support wall 14; Reference Figure 1, when adding the soil sample, the upper cover 1402 and the torque application fixing buckle 3 can be removed to expose the upper part of the soil sample chamber 1, and then the soil sample can be added into the soil sample chamber 1; the soil sample loading bottom plate 17 and the rubber membrane 7 can ensure the stability of the soil sample. The rubber membrane 7 can isolate the soil sample chamber 1 from the pressure chamber 6 and meet the requirement of the pressure chamber 6 to apply circumferential pressure to the soil sample chamber 1, ensuring good pressure transmission and no pressure loss; the pressure chamber 6 is used to hold the freezing liquid, and the temperature of the freezing liquid is used to simulate the experimental temperature of unsaturated frozen soil. By changing the temperature of the freezing liquid, the test temperature of unsaturated frozen soil can be changed. The highest temperature is 1 °C, which is suitable for the test of unsaturated frozen soil in the high-temperature state. The change of the freezing liquid temperature can be provided by the freezing equipment in the existing technology.

[0029] In terms of sealing, by the mutual cooperation of the rubber membrane 7, the soil sample loading bottom plate 17, the hollow cylinder 2, and the torque application fixing buckle 3, the resistance of the torque transmission shaft 11 can be reduced to 0.1 N - 1.0 N on the premise of ensuring the sealing performance, and the accuracy reaches 0.5 kPa (for a 50 mm specimen). The specific data can be seen in: the friction force test table of the axial force sealing system;

[0030] The self-feeding component is used to automatically control the amount of antifreeze injected into the pressure chamber 6 according to the difference between the volume change pressure value and the standard pressure value of the pressure chamber 6; The self-feeding component includes a liquid pumping device 16, a standard pressure feedback device 18, a pressure controller 19, a water level balancer 21, and a volume change test sensor 10. The volume change test sensor 10, the pressure controller 19, the liquid pumping device 16, and the standard pressure feedback device 18 are all arranged in the bottom box 1401, and the water level balancer 21 is arranged outside the reaction support wall 14; the volume change test sensor 10 is used to monitor the pressure value in the pressure chamber 6, the liquid pumping device 16 is used to extract or pump the antifreeze liquid at the target temperature into the pressure chamber 6, the standard pressure feedback device 18 is used to calculate the difference between the pressure value in the pressure chamber 6 and the standard value, and the pressure controller 19 is used to control the operation of the liquid pumping device 16 according to the difference; Reference Figure 2 , the liquid pumping device 16 can be a pump body, such as a centrifugal pump, which is used to extract or pump the antifreeze liquid at the target temperature into the pressure chamber 6. The antifreeze can adopt ethylene glycol solution, and with the cooperation of valves and pipelines, the temperature of the soil sample can be controlled to make the soil sample meet the test temperature requirements; the water level balancer 21 is used to judge whether the whole device is in a horizontal placement state; the standard pressure feedback device 18, the water level balancer 21, the volume change test sensor 10, the pressure controller 19, the temperature sensor 5, and the computer 20 are all existing components and can be directly purchased from the market.

[0031] It further includes a computer 20, which is electrically connected to the standard pressure feedback device 18, the pressure controller 19, the water level balancer 21, the temperature sensor 5, the volume change test sensor 10, the torsion device, the torsion controller, and the data acquisition master controller 12. The computer 20 is used for setting test schemes and collecting and analyzing test data; This embodiment also provides a self-feed type high-temperature unsaturated frozen soil interface shear test method. Using the above-mentioned self-feed type high-temperature unsaturated frozen soil interface shear test device, it includes the following steps. Step 1: Test preparation; comprehensively check the overall device to ensure the airtightness of the overall device, the good condition of the sensors, and discharge the air in all pipelines of the device. Select a shear plate 13 with an appropriate friction coefficient according to the properties of the soil sample. Step 2: Placing the soil sample; place the soil sample into the soil sample chamber 1. Step 3: Saturation and consolidation of the soil sample; start the gas-phase injection component and the liquid-phase injection component, and use backpressure saturation combined with relevant saturation methods to saturate the soil sample to meet the saturation requirements of the test. Step 4: Shear test, start the self-feed component and the torsion loading component, so that the soil sample is driven by torsion under the action of hydraulic pressure, and record the test data.

[0032] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A self-feed type high-temperature unsaturated frozen soil interface shear test device, characterized in that Comprising: A housing assembly, which sequentially includes a bottom box (1401), a reaction support wall (14), and a detachable upper cover (1402) from bottom to top; A torsion loading assembly, which is arranged inside the housing assembly and is used to apply torsion to the soil sample; the torsion loading assembly includes a torsion control box (15) arranged inside the bottom box (1401), a torsion controller and a general data acquisition controller (12), and a torsion device are arranged inside the torsion control box (15), the output end of the torsion device is fixedly connected with a hollow cylinder (2) through a torsion transmission shaft (11), a plurality of shear plates (13) are detachably connected to the hollow cylinder (2), a torsion application fixing buckle (3) is detachably connected to the upper part of the hollow cylinder (2), and a plurality of temperature sensors (5) are installed on the circumferential surface of the hollow cylinder (2); A matrix suction control system, which includes a gas phase injection component and a liquid phase injection component, the gas phase injection component is arranged at the top of the reaction support wall (14) and is used to introduce gas into the soil sample; The liquid phase injection component is arranged on the hollow cylinder (2) and is used to introduce liquid into the soil sample; the liquid phase injection component includes a water inlet device (9) and a water equalizing component (22), the water equalizing component (22) is arranged on the hollow cylinder (2), the water equalizing component (22) includes a flushing pipeline (2201), the water outlet end of the water inlet device (9) is communicated with the flushing pipeline (2201), control valves (2202) and ceramic plates (2203) are alternately arranged on the flushing pipeline (2201), and an S-shaped cavity (31) is arranged inside the ceramic plate (2203); The gas phase injection component includes an air inlet device (8), and the air outlet end of the air inlet device (8) is communicated with the flushing pipeline (2201) through a pipeline; A soil sample accommodation component, which is arranged inside the reaction support wall (14) and is used to hold the soil sample; the soil sample accommodation component includes a soil sample loading bottom plate (17) fixedly installed on the bottom box (1401), a rubber membrane (7) is concentrically and fixedly connected to the soil sample loading bottom plate (17), the torsion transmission shaft (11) passes through the soil sample loading bottom plate (17) and is in rotational fit with each other, a soil sample cavity (1) is formed between the rubber membrane (7) and the hollow cylinder (2), and a pressure cavity (6) is formed between the rubber membrane (7) and the reaction support wall (14); A self-feeding component, which is used to automatically control the amount of antifreeze injected into the pressure cavity (6) according to the difference between the volume change pressure value and the standard pressure value of the pressure cavity (6).

2. The self-feed type high-temperature unsaturated frozen soil interface shear test device according to claim 1, characterized in that: The bottom box (1401) is fixedly connected to the reaction support wall (14), the reaction support wall (14) is tubular, and an upper load part is arranged at the center of the upper cover (1402), and the upper load part is in contact with the torsion application fixing buckle (3).

3. The self-feed type high-temperature unsaturated frozen soil interface shear test device according to claim 1, characterized in that: The lower surface of the torsion application fixing buckle (3) is fixedly connected with a needle and / or a blade for embedding into the soil sample, and a clamping part (1301) is arranged on the shear plate (13), and the clamping part (1301) is clamped with the hollow cylinder (2).

4. A self-feed high-temperature unsaturated frozen soil interface shear test device according to claim 1, characterized in that: The self-feed component includes a liquid pumping device (16), a standard pressure feedback device (18), a pressure controller (19), a water level balancer (21), and a volume change test sensor (10). The volume change test sensor (10), the pressure controller (19), the liquid pumping device (16), and the standard pressure feedback device (18) are all arranged in the bottom box (1401), and the water level balancer (21) is arranged outside the reaction support wall (14). The volume change test sensor (10) is used to monitor the pressure value in the pressure chamber (6). The liquid pumping device (16) is used to extract or pump the antifreeze liquid at the target temperature into the pressure chamber (6). The standard pressure feedback device (18) is used to calculate the difference between the pressure value in the pressure chamber (6) and the standard value. The pressure controller (19) is used to control the operation of the liquid pumping device (16) according to the difference.

5. A self-feeding high-temperature unsaturated frozen soil interface shear test device according to claim 1, characterized in that: It further includes a computer (20). The computer (20) is electrically connected to the standard pressure feedback device (18), the pressure controller (19), the water level balancer (21), the temperature sensor (5), the volume change test sensor (10), the torsion device, the torsion controller, and the data acquisition master controller (12). The computer (20) is used for setting the test plan and collecting and analyzing the test data.

6. A self-feed type high-temperature unsaturated frozen soil interface shear test method, which uses a self-feed type high-temperature unsaturated frozen soil interface shear test device as described in any one of claims 1-5, and is characterized in that, It includes the following steps: Step 1: Test preparation; comprehensively check the overall device to ensure the airtightness of the overall device, the good condition of the sensors, and discharge the air in all pipelines of the device. Select a shear plate (13) with an appropriate friction coefficient according to the properties of the soil sample. Step 2: Place the soil sample; place the soil sample into the soil sample chamber (1). Step 3: Saturate and consolidate the soil sample; start the gas-phase placement component and the liquid-phase placement component, and use backpressure saturation combined with relevant saturation methods to saturate the soil sample to meet the saturation requirements of the test. Step 4: Shear test, start the self-feed component and the torsion loading component, pump the antifreeze liquid at the target temperature into the pressure chamber (6), so that the soil sample is driven by torsion under the action of the preset hydraulic pressure and temperature, and record the test data.

Images