Frozen soil resistance measuring device and method

Abstract

The invention belongs to the technical field of frozen soil resistance measurement, and particularly relates to a frozen soil resistance measuring device and method.On one hand, soil and water are mixed in the form of frozen soil and ice particles, and in the mixing process, due to the influence of low temperature and the physical state of the ice particles, the resistance of the frozen soil is measured; compared with the prior art, the method has the advantages that the ice particles are added into the soil, so that the viscosity generated between the soil and the ice particles is small, the soil particles and the ice particles are quickly mixed, then the ice particles are gradually dissolved through multiple freezing and thawing treatment, are absorbed by the soil and are finally frozen into ice in the soil, and the natural frozen soil is simulated. The soil and water are directly mixed and frozen, so that the influence of viscosity on diffusion of water in the soil can be effectively reduced, the water is uniformly diffused in the soil, ice particles are ensured to be completely melted and the melted water is well combined with the soil by utilizing a multi-time freezing and thawing mode so as to simulate the soil in the natural world. The frozen soil is in a freeze-thaw state in summer and winter.

Description

Technical Field

[0001] The present invention belongs to the technical field of frozen soil resistivity measurement, and specifically relates to a frozen soil resistivity measurement device and method. Background Art

[0002] In activities such as studying the characteristics of frozen soil, monitoring the changes of frozen soil, and evaluating engineering geological conditions, the test of frozen soil resistivity is an important technical means to reveal the correlation between the electrical properties and physical state of frozen soil. Among them, by converting the resistance of a saturated frozen soil sample into a parallel form of the resistances of soil particles, pore water, and pore ice, and deriving the resistivity of the frozen soil sample, it is one of the ways to determine the unfrozen water content in the frozen soil.

[0003] In the experiment of studying the changes in resistivity, unfrozen water content, and temperature during the freezing process of soil, it is necessary to measure the resistivity of frozen soil in the frozen and thawed states. Among them, in order to reveal the influence of the initial water content in the soil sample on the experiment, it is usually necessary to prepare multiple soil samples with different initial water contents for the experiment. In order to enhance the consistency of the parameters of multiple soil samples except for the initial water content, soil and water are also manually taken to manufacture the soil samples artificially. However, since the soil becomes sticky after being broken and mixed with water, and the combination effect of water and soil is good, it is not convenient to evenly disperse the water in the soil, resulting in a small degree of uniform water distribution in the manufactured soil samples.

[0004] A related technology discloses a frozen soil sample preparation system with the publication number CN112067386B. In this solution, a stirring mechanism is first used to stir the soil raw materials evenly. Specifically, the soil raw materials are put into the first housing, the rotation driving part is started, the output shaft of the rotation driving part drives the tube body to rotate through the horizontal shaft, and the tube body drives the crushing hammer to rotate through the stirring part. The crushing hammer first crushes the soil raw materials, and then the stirring part stirs the soil raw materials evenly, replacing the traditional manual stirring, improving the stirring effect and efficiency. However, it is found in the actual application process that due to the influence of the viscosity of the mixture of soil and water, the mixing of soil and water is still relatively difficult, and during the sample preparation process, the mud sample formed by the mixture of soil and water is very easy to adhere to the crushing equipment, and in severe cases, it may even cause the equipment to fail to operate normally, thus making the sample manufacturing more troublesome.

[0005] In view of this, the present invention proposes a frozen soil resistivity measurement device and method to solve the above technical problems. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art and solve the above technical problems, the present invention proposes a frozen soil resistivity measurement device and method.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A method for measuring the soil resistance of frozen soil according to the present invention includes the following steps:

[0008] S1. Sample preparation: In a freeze-thaw test bench, the selected soil is crushed and dried at 40-50 °C in a drying chamber to obtain a soil sample with a water content of 2%, and deionized water is frozen and crushed in a negative temperature environment in a freezing chamber to obtain an ice particle sample;

[0009] S2. Sample blending: The soil sample and the ice particle sample are fed into a mixing component, and the conveying rate of the ice particle sample is manually adjusted to mix and lay the soil sample and the ice particle sample in a sample tube to obtain a mixed sample;

[0010] S3. Freeze-thaw measurement: The sample tube containing the mixed sample is alternately dissolved and frozen in a positive temperature environment and a negative temperature environment for multiple times to obtain a frozen soil sample, and then the resistivity and unfrozen water content of the frozen soil sample are measured by the frequency domain measurement method;

[0011] The particle size ranges of both the soil sample and the ice particle sample are 2-4 mm.

[0012] Preferably, before the soil sample is added to the mixing component in S2, it is hermetically transferred to a negative temperature environment and frozen to -3 to -1 °C.

[0013] Preferably, the freeze-thaw test bench in S1 includes an operation table and a mixing freeze-thaw mechanism installed on the operation table;

[0014] The mixing freeze-thaw mechanism is used to prepare a soil sample in a freeze-thaw state, and the mixing freeze-thaw mechanism includes a cold and heat circulator, a sample tube, and a mixing component;

[0015] A freezing chamber and a drying chamber are provided on the operation table, the cold and heat circulator is installed on the operation table, and the cold and heat circulator is used to refrigerate the freezing chamber and heat the drying chamber;

[0016] The mixing component includes a material bin, a feeding pipe, and a mixing tray;

[0017] The material bin is installed on the operation table, the number of inner chambers of the material bin is two, which are respectively used to store the soil sample and the ice particle sample, a feeding pipe is installed at the bottom of the material bin, the feeding pipe extends into the mixing tray, the mixing tray is a funnel-shaped structure with a closed top, and the feeding pipes all extend into the mixing tray along the tangential direction of the mixing tray, and the mixing tray is used to convey the mixed sample into the sample tube.

[0018] Preferably, the mixing assembly further includes a circulation pump and an air supply pipe. The circulation pump is evenly divided into two groups, and the input ends of the two groups of circulation pumps are respectively connected to the freezing chamber and the drying chamber in a conducting manner. The output ends of the two groups of circulation pumps are fixedly installed with air supply pipes, and the two air supply pipes respectively extend into the sample tube and the feeding pipe.

[0019] Preferably, a docking pipe is installed at the bottom of the mixing tray. The diameter of the docking pipe is larger than the opening diameter at the bottom of the mixing tray and smaller than the diameter of the sample tube. A plurality of upwardly inclined air holes are provided on the docking pipe.

[0020] Preferably, a freeze-thaw chamber is provided on the operating table. The freeze-thaw chamber is located between the freezing chamber and the drying chamber. A turntable is installed at the bottom of the freeze-thaw chamber. The turntable is externally connected to a driving motor. In the initial state, the sample tube is placed on the turntable. A weighing device is inlaid on the turntable, and the weighing device is used to measure the weight of the sample tube.

[0021] Preferably, a guiding frame is fixedly installed in the freeze-thaw chamber. The guiding frame is designed in a spiral shape. The two sides of the freeze-thaw chamber are respectively connected to the freezing chamber and the drying chamber in a conducting manner. In the initial state, the sample tube is located in the middle of the guiding frame.

[0022] Preferably, a partition is detachably and fixedly installed in the freeze-thaw chamber. The partition cooperates with the guiding frame, and the partition divides the freeze-thaw chamber into two chambers.

[0023] Preferably, the partition is composed of a mounting plate and a labyrinth sealing sheet made of elastic rubber material. The mounting plate is detachably installed above the guiding frame. The labyrinth sealing sheet is fixedly installed below the mounting plate. The labyrinth sealing sheet extends into the gaps of the guiding frame and is used to partition the spiral chamber of the guiding frame.

[0024] A device for measuring the soil resistance of frozen soil includes a freeze-thaw test bench and further includes a frequency domain measuring device. The frequency domain measuring device is installed on the operating table, and the frequency domain measuring device is used to measure the soil resistivity and the unfrozen water content.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. An apparatus and method for measuring the electrical resistance of frozen soil according to the present invention. On the one hand, the soil and water are mixed in the form of frozen soil and ice particles. During the mixing process, due to the influence of low temperature and the physical state of the ice particles, the viscosity between the soil and the ice particles is small, which facilitates the rapid mixing of soil particles and ice particles. Subsequently, through multiple freeze-thaw treatments, the ice particles gradually dissolve and are absorbed by the soil, and finally freeze into ice inside the soil, thereby realizing the simulation of natural frozen soil. Compared with the prior art method of directly mixing and freezing soil and water, this method can not only effectively reduce the influence of viscosity on the diffusion of water in the soil, making the water diffuse more uniformly in the soil, but also use the multiple freeze-thaw method to ensure that the ice particles are completely melted and the melted water combines well with the soil to simulate the freeze-thaw state of frozen soil in summer and winter in nature.

[0027] 2. An apparatus and method for measuring the electrical resistance of frozen soil according to the present invention promote the transportation and mixing of soil particles and ice particles by using positive-temperature air flow and negative-temperature air flow. On the one hand, during the transportation process, the negative-temperature state of the soil and ice particles is maintained, and the negative-temperature state is used to maintain the stability of the morphology of the soil and ice particles, so as to facilitate the mixing of the soil and ice particles. On the other hand, after mixing and filling, the positive-temperature air flow is used to promote the micro-dissolution phenomenon between the soil and ice particles, so that the soil and ice particles are mixed into a whole. At this time, the micro-dissolution of the soil and ice particles, combined with the subsequent cyclic freeze-thaw, enhances the adsorption effect of the soil on water. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 is the flowchart of the method of the present invention;

[0030] Figure 2 is the perspective view of the freeze-thaw test bench of the present invention;

[0031] Figure 3 is the perspective view of the mixing component;

[0032] Figure 4 is the cross-sectional view of the mixing component;

[0033] Figure 5 is the transverse cross-sectional view of the silo;

[0034] Figure 6 is the perspective view of the operating table;

[0035] Figure 7 is the exploded view of the guide frame and the partition;

[0036] Figure 8 is the exploded view of the labyrinth seal;

[0037] Figure 9It is a sectional view of the freeze-thaw test bench;

[0038] In the figure: 1. Operating table; 11. Freezing chamber; 12. Drying chamber; 13. Freeze-thaw chamber; 2. Silo; 21. Feeding pipe; 22. Mixing tray; 23. Circulation pump; 24. Air supply pipe; 25. Docking pipe; 26. Air outlet; 3. Turntable; 31. Driving motor; 32. Guide frame; 4. Mounting plate; 41. Labyrinth seal; 5. Sample tube. Specific embodiments

[0039] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0040] As Figures 1 to 9 shown, a method for measuring the soil resistance of frozen soil according to the present invention includes the following steps:

[0041] S1. Sample preparation: In the freeze-thaw test bench, the selected soil is crushed and dried at 40-50°C in the drying chamber 12 to obtain a soil sample with a water content of 2%, and deionized water is frozen and crushed in the negative temperature environment of the freezing chamber 11 to obtain an ice particle sample;

[0042] S2. Sample blending: The soil sample and the ice particle sample are fed into the mixing assembly, and the conveying rate of the ice particle sample is manually adjusted, and the soil sample and the ice particle sample are mixed and laid in the sample tube 5 to obtain a mixed sample;

[0043] S3. Freeze-thaw measurement: The sample tube 5 containing the mixed sample is alternately dissolved and frozen in a positive temperature environment and a negative temperature environment for multiple times to obtain a frozen soil sample, and then the resistivity and unfrozen water content of the frozen soil sample are measured by the frequency domain measurement method;

[0044] The particle size ranges of both the soil sample and the ice particle sample are 2-4 mm.

[0045] Before the soil sample in S2 is added to the mixing assembly, it is hermetically transferred to a negative temperature environment and frozen to -3 to -1°C.

[0046] During the conventional unfrozen water content test of frozen soil, in order to measure the influence of the initial water content of the frozen soil sample itself on the experiment, frozen soil samples are usually made in the laboratory, and during the production process, the initial water content is controlled to form multiple frozen soil samples with gradient-arranged initial water contents. The difference between the frozen soil sample and the natural frozen soil in nature during this process determines the authenticity of the experimental data obtained with the frozen soil sample as the experimental object. Therefore, the present invention changes the sample manufacturing process, reduces the difference between the frozen soil sample and the natural frozen soil in nature, and enhances the convenience of manufacturing the frozen soil sample.

[0047] Specifically, in the measurement process of the resistivity of frozen soil with different initial water contents, it is first necessary to manufacture frozen soil samples in the laboratory. The soil used in the frozen soil samples is the soil remaining after removing impurities and stones from natural soil. The soil is first dried and crushed at 40 - 50 °C. During the drying process, the water content of the soil is measured at regular intervals until the water content of the soil sample drops to 2%. Subsequently, deionized water is frozen in a negative temperature environment, and the ice cubes are crushed using a crusher to obtain ice particle samples. During the crushing process of the ice and the soil, it is necessary to control the particle sizes of the soil sample and the ice particle sample. The particle size is preferably 2 - 4 mm, and in actual operation, it is better that the particle sizes of the soil and the ice particles are close. Then, to prevent the melting phenomenon from occurring when the soil sample and the ice particle sample are mixed, before sample preparation, the soil sample is frozen to -3 - -1 °C in a negative temperature environment. Since the water content of the soil sample decreases at this time, although the frozen soil sample shows some caking phenomenon to a certain extent, the degree of caking is relatively low and it is easy to be broken. At this time, the soil sample after being broken again and the ice particle sample are mixed in a freeze-thaw test bench according to the weight ratio. At this time, the particle sizes of the soil sample and the proportion sample are close and the viscosity is low, so that the mixing of soil particles and ice particles is relatively simple. After the soil and ice particles are mixed, since both the soil and the ice particles are granular, the mixed sample not only has a large gap but also does not conform to the state of natural frozen soil. Therefore, during sample preparation, the sample tube 5 containing the mixed sample is first placed in a positive temperature environment. As the temperature of the mixed sample continues to rise, the ice particles gradually melt into water, and the water is adsorbed by the soil. Subsequently, the sample tube 5 is placed in a negative temperature environment, and the negative temperature environment is used to freeze the mixed sample, causing the water in the soil to freeze. After repeating this process several times, the water and the soil are combined more evenly. At this time, the mixed sample is frozen again to obtain frozen soil close to the natural state. Taking this embodiment as a reference, in this embodiment, the diameter of the sample tube 5 is 10 cm and the height is 10 cm. After the mixed sample is filled, the sample tube 5 is placed at 30 - 50 °C for 6 - 12 min, and then the sample tube 5 is placed at -10 - -8 °C for freezing for 6 - 12 min. After repeating three times, the sample tube 5 is placed in a negative temperature environment for freezing. At this time, the frequency domain measurement method can be used to measure the frozen soil sample. During the measurement, the FDR probe is inserted into the frozen soil, and electromagnetic waves of a specific frequency are emitted. By receiving the reflected signal and analyzing the amplitude and phase changes of the signal through Fourier transform, the resistivity and unfrozen water content of the soil can be calculated and converted.

[0048] On the one hand, the present invention mixes soil and water in the form of frozen soil and ice particles. During the mixing process, due to the low temperature and the physical state of the ice particles, the viscosity between the soil and the ice particles is small, which facilitates the rapid mixing of soil particles and ice particles. Subsequently, through multiple freeze-thaw treatments, the ice particles gradually dissolve and are absorbed by the soil, and finally freeze into ice inside the soil, thereby simulating natural frozen soil. Compared with the prior art method of directly mixing and freezing soil and water, it can not only effectively reduce the influence of viscosity on the diffusion of water in the soil, making the water diffuse more evenly in the soil, but also use multiple freeze-thaw methods to ensure that the ice particles completely melt and the melted water combines well with the soil to simulate the freeze-thaw state of frozen soil in summer and winter in nature.

[0049] As a preferred embodiment of the present invention, the freeze-thaw test bench in S1 includes an operation table 1 and a mixing and freeze-thaw mechanism installed on the operation table 1;

[0050] The mixing and freeze-thaw mechanism is used to prepare a soil sample in a freeze-thaw state, and the mixing and freeze-thaw mechanism includes a cooling and heating circulator, a sample tube 5 and a mixing component;

[0051] A freezing chamber 11 and a drying chamber 12 are opened on the operation table 1, the cooling and heating circulator is installed on the operation table 1, and the cooling and heating circulator is used to cool the freezing chamber 11 and heat the drying chamber 12;

[0052] The mixing component includes a material bin 2, a feeding pipe 21 and a mixing tray 22;

[0053] The material bin 2 is installed on the operation table 1. The number of inner cavities of the material bin 2 is two, which are respectively used to store soil specimens and ice particle specimens. A feeding pipe 21 is installed at the bottom of the material bin 2, and the feeding pipe 21 extends into the mixing tray 22. The mixing tray 22 is a funnel-shaped structure with a closed top. The feeding pipes 21 all extend into the mixing tray 22 along the tangential direction of the mixing tray 22, and the mixing tray 22 is used to transport the mixed sample into the sample tube 5.

[0054] In order to further enhance the convenience of manufacturing frozen soil samples, the freeze-thaw test bench in the present invention includes an operation table 1 and a mixing freeze-thaw mechanism. Among them, a freezing chamber 11 and a drying chamber 12 are provided on the operation table 1, which are respectively used to provide a negative temperature environment and a positive temperature environment. The cooling and heating circulator is composed of a compressor, a condenser, an evaporator, an expansion valve, a refrigerant and a radiator fan (this is conventional prior art and will not be elaborated here). Under the action of the cooling and heating circulator, heat is continuously transferred from the freezing chamber 11 to the drying chamber 12, thereby realizing the freezing of water in the freezing chamber 11 and the drying of soil in the drying chamber 12. Then, the dried soil and frozen water are broken and sent into the feed bin 2, and flow from the bottom of the feed bin 2 to the feed pipe 21 and the mixing tray 22. It should be noted that an electromagnetic screw conveyor is installed between the feed bin 2 and the feed pipe 21 to control the rate of the transported soil particles and ice particles. Under the action of gravity, the soil particles and ice particles fall into the mixing tray 22 and are mixed during the rolling along the mixing tray 22. The mixed sample falls from the bottom opening of the mixing tray 22 into the sample tube 5, thereby realizing the filling and mixing of soil and ice particles. It should be noted that the feed bin 2 is made of heat-insulating and heat-preserving materials, which is convenient to maintain the low temperature state of soil and ice particles during the manufacturing process of frozen soil samples with multiple different initial water contents.

[0055] As a preferred embodiment of the present invention, the mixing assembly further includes a circulation pump 23 and an air supply pipe 24. The circulation pump 23 is evenly divided into two groups, and the input ends of the two groups of circulation pumps 23 are respectively connected in communication with the freezing chamber 11 and the drying chamber 12. The output ends of the two groups of circulation pumps 23 are fixedly installed with air supply pipes 24, and the two groups of air supply pipes 24 respectively extend into the sample tube 5 and the feed pipe 21. It should be noted that one-way air inlet valves are installed in both the freezing chamber 11 and the drying chamber 12, so that gas can be supplemented from the outside when the circulation pump 23 extracts air, and after the circulation pump is started, the cooling and heating circulator operates under the control of a preset program to continuously supply cold and hot air.

[0056] A docking pipe 25 is installed at the bottom of the mixing tray 22. The diameter of the docking pipe 25 is larger than the diameter of the bottom opening of the mixing tray 22 and smaller than the diameter of the sample tube 5. A plurality of upwardly inclined air outlet holes 26 are provided on the docking pipe 25.

[0057] In order to make the combination of soil and ice particles more stable, in practical applications, two groups of circulation pumps 23 are respectively connected in communication with the freezing chamber 11 and the drying chamber 12. During the feeding process, the circulation pump 23 connected in communication with the freezing chamber 11 transports low-temperature air into the sample delivery tube through the air delivery pipe 24. Since the sample delivery tube extends tangentially along the mixing tray 22 into its interior, when the air flow pushes the soil particles and ice particles into the mixing tray 22, they will move in a spiral motion along the inner wall of the funnel-shaped mixing tray 22 under the action of the air flow and gravity. During this process, the mixing of ice particles and soil particles is achieved, and the presence of low-temperature air can effectively maintain the low-temperature state of soil particles and ice particles. The circulation pump 23 connected in communication with the drying chamber 12 transports positive-temperature air into the sample tube 5 through the air delivery pipe 24. The positive-temperature air blows on the mixed sample of soil and ice particles, causing the soil and ice particles to melt. In practical applications, by controlling the air flow pumping efficiency of the circulation pump 23 and the temperature in the drying chamber 12, the melting degree of soil and ice particles can be effectively controlled. In actual operation, it is preferably that the volume of ice particles decreases by 1 / 3 to 1 / 2. As the soil and ice particles are stacked step by step, the positive-temperature air causes the soil and ice particles to melt layer by layer. The water generated by melting increases the viscosity between the soil and ice particles, causing the mixed sample to form a whole, so as to avoid stratification of the loaded soil and ice particles under the action of external factors such as vibration. When the mixed sample is being transported, since the diameter of the docking pipe 25 is larger than the opening diameter of the mixing tray 22 and smaller than the diameter of the sample tube 5, the docking pipe 25 can not only drain the mixed sample, but also the mixed sample is not easily in contact with the inner wall of the docking pipe 25, and at the same time, the air flow can be discharged from the air outlet 26.

[0058] The present invention promotes the transportation and mixing of soil particles and ice particles by using positive-temperature air flow and negative-temperature air flow. On the one hand, during the transportation process, the negative-temperature state of soil and ice particles is maintained, and the negative-temperature state is used to maintain the stability of the forms of soil and ice particles, so as to facilitate the mixing of soil and ice particles. On the other hand, after mixing and loading, the positive-temperature air flow is used to cause the soil and ice particles to produce a micro-melting phenomenon, so that the soil and ice particles are mixed into a whole. And at this time, the micro-melting of soil and ice particles, combined with subsequent cyclic freeze-thaw, enhances the water adsorption effect of the soil.

[0059] As a preferred embodiment of the present invention, a freeze-thaw chamber 13 is provided on the operating table 1. The freeze-thaw chamber 13 is located between the freezing chamber 11 and the drying chamber 12. A turntable 3 is installed at the bottom of the freeze-thaw chamber 13. The turntable 3 is externally connected to a driving motor 31. In the initial state, the sample tube 5 is placed on the turntable 3. A weighing device is inlaid on the turntable 3, and the weighing device is used to measure the weight of the sample tube 5.

[0060] A guiding frame 32 is fixedly installed in the freeze-thaw chamber 13. The guiding frame 32 is designed in a spiral shape. Both sides of the freeze-thaw chamber 13 are respectively connected to the freezing chamber 11 and the drying chamber 12 in a conducting manner. In the initial state, the sample tube 5 is located in the middle of the guiding frame 32.

[0061] A partition member is detachably and fixedly installed in the freeze-thaw chamber 13. The partition member is matched with the guiding frame 32, and the partition member divides the freeze-thaw chamber 13 into two chambers.

[0062] The partition member is composed of a mounting plate 4 and a labyrinth sealing sheet 41 made of an elastic rubber material. The mounting plate 4 is detachably installed above the guiding frame 32. The labyrinth sealing sheet 41 is fixedly installed below the mounting plate 4. The labyrinth sealing sheet 41 extends into the gap of the guiding frame 32 and is used to partition the spiral chamber of the guiding frame 32. The labyrinth sealing sheet 41 is composed of a plurality of alternately arranged elastic rubber sheets. When the sample tube 5 moves, the sample tube 5 can directly push the labyrinth sealing sheet 41 to deform. After the sample tube 5 moves away, under its own elastic action, the labyrinth sealing sheet 41 can form a labyrinth seal again to reduce the mutual influence between both sides of the freeze-thaw chamber 13.

[0063] During actual operation, the sample tube 5 is placed in the middle of the spiral of the guiding frame 32 through the top opening of the freeze-thaw chamber 13. Subsequently, with the cooperation of the electromagnetic screw conveyor at the bottom of the hopper and the weighing device on the turntable 3, the filling of the mixed sample is achieved. At this time, the staff causes the driving motor 31 to start through the pre-installed controller. The driving motor 31 drives the turntable 3 to rotate. The turntable 3 and the sample tube 5 are driven by friction. As a result, the sample tube 5 moves along the spiral structure of the guiding frame 32. During this process, since both sides of the freeze-thaw chamber 13 are respectively communicated with the freezing chamber 11 and the drying chamber 12, and with the setting of the partition member, both sides of the freeze-thaw chamber 13 are respectively in a positive temperature state and a negative temperature state. Therefore, when the sample tube 5 moves along the guiding frame 32, the sample tube 5 switches between a negative temperature environment and a positive temperature environment during the movement cycle. And due to the limitation of the spiral structure, during the process of the sample tube 5 moving from the middle of the guiding frame 32 to the end of the guiding frame 32, the time of its being in the positive temperature state and the negative temperature state gradually extends. Taking this embodiment as an example, at the initial stage of the sample tube 5 moving along the guiding frame 32, the switching cycle of the sample tube 5 between the positive temperature environment and the negative temperature environment tends to be 6 - 8 minutes, while when the sample tube 5 approaches the end of the guiding frame 32, the switching cycle of the sample tube 5 between the positive temperature environment and the negative temperature environment tends to be 10 - 12 minutes. This is because at the initial stage of the freeze-thaw treatment, the ice particles are separated from the soil. At this time, the ice particles melt, and in addition to combining with the soil, part of the melted water flows along the soil gaps. Therefore, a facility with a short alternating cycle between the positive temperature environment and the negative temperature environment can provide time for the combination of soil and water and reduce the degree of the melted water flowing downward along the gaps. In the later stage, most of the water has combined with the soil. At this time, extending the alternating cycle between the positive temperature environment and the negative temperature environment can make the frozen soil sample more thoroughly convert between the frozen state and the melted state to simulate the freeze-thaw state of natural frozen soil in summer and winter.

[0064] A device for measuring the resistance of frozen soil, which includes a freeze-thaw test bench and a frequency domain measuring device. The frequency domain measuring device is installed on the operating table 1, and the frequency domain measuring device is used to measure the soil resistivity and the unfrozen water content.

[0065] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the soil resistance of frozen soil, characterized in that, The method includes the following steps: S1. Sample preparation: In a freeze-thaw test bench, the selected soil is broken and dried at 40 - 50 °C in a drying chamber (12) to obtain a soil sample with a water content of 2%. Deionized water is frozen and broken in a negative temperature environment in a freezing chamber (11) to obtain an ice particle sample; S2. Sample blending: The soil sample and the ice particle sample are fed into a mixing component, and the conveying rate of the ice particle sample is manually adjusted to mix and lay the soil sample and the ice particle sample in a sample tube (5) to obtain a mixed sample; S3. Freeze-thaw measurement: The sample tube (5) containing the mixed sample is alternately dissolved and frozen multiple times in a positive temperature environment and a negative temperature environment to obtain a frozen soil sample. Subsequently, the resistivity and unfrozen water content of the frozen soil sample are measured by the frequency domain measurement method; The particle size ranges of both the soil sample and the ice particle sample are 2 - 4 mm.

2. The method for measuring the resistance of frozen soil according to claim 1, wherein: In S2, before the soil sample is added to the mixing component, it is hermetically transferred to a negative temperature environment and frozen to -3 - -1 °C.

3. A method for measuring the soil resistance of frozen soil according to claim 1, characterized in that: In S1, the freeze-thaw test bench includes an operating table (1) and a mixed freeze-thaw mechanism installed on the operating table (1); The mixed freeze-thaw mechanism is used to prepare a soil sample in a freeze-thaw state. The mixed freeze-thaw mechanism includes a cooling and heating circulator, a sample tube (5), and a mixing component; A freezing chamber (11) and a drying chamber (12) are provided on the operating table (1). The cooling and heating circulator is installed on the operating table (1), and the cooling and heating circulator is used to refrigerate the freezing chamber (11) and heat the drying chamber (12); The mixing component includes a feed bin (2), a feed pipe (21), and a mixing tray (22); The feed bin (2) is installed on the operating table (1). The number of inner chambers of the feed bin (2) is two, which are respectively used to store the soil sample and the ice particle sample. A feed pipe (21) is installed at the bottom of the feed bin (2), and the feed pipe (21) extends into the mixing tray (22). The mixing tray (22) is a funnel-shaped structure with a closed top. The feed pipes (21) all extend into the mixing tray (22) along the tangential direction of the mixing tray (22). The mixing tray (22) is used to convey the mixed sample into the sample tube (5); 4. A method for measuring the resistance of frozen soil according to claim 3, characterized in that: The mixing component further includes a circulation pump (23) and an air supply pipe (24). The circulation pump (23) is divided into two groups on average. The input ends of the two groups of circulation pumps (23) are respectively connected to the freezing chamber (11) and the drying chamber (12) in a conducting manner. The output ends of the two groups of circulation pumps (23) are both fixedly installed with air supply pipes (24), and the two groups of air supply pipes (24) respectively extend into the sample tube (5) and the feed pipe (21); 5. A method for measuring the resistance of frozen soil according to claim 4, characterized in that: A docking pipe (25) is installed at the bottom of the mixing tray (22). The diameter of the docking pipe (25) is larger than the bottom opening diameter of the mixing tray (22) and smaller than the diameter of the sample tube (5). A plurality of upwardly inclined air outlet holes (26) are provided on the docking pipe (25).

6. The method for measuring the resistance of frozen soil according to claim 5, characterized in that: A thawing and freezing chamber (13) is provided on the operation table (1). The thawing and freezing chamber (13) is located between the freezing chamber (11) and the drying chamber (12). A turntable (3) is installed at the bottom of the thawing and freezing chamber (13). The turntable (3) is externally connected to a driving motor (31). In the initial state, the sample tube (5) is placed on the turntable (3). A weighing device is inlaid on the turntable (3), and the weighing device is used to measure the weight of the sample tube (5).

7. A method for measuring the soil resistance of frozen soil according to claim 6, characterized in that: A guiding frame (32) is fixedly installed in the thawing and freezing chamber (13). The guiding frame (32) is designed in a spiral shape. Both sides of the thawing and freezing chamber (13) are respectively connected to the freezing chamber (11) and the drying chamber (12) in a conducting manner. In the initial state, the sample tube (5) is located in the middle of the guiding frame (32).

8. A method for measuring the resistance of frozen soil according to claim 7, characterized in that: A partition member is detachably and fixedly installed in the thawing and freezing chamber (13). The partition member is matched with the guiding frame (32), and the partition member divides the thawing and freezing chamber (13) into two chambers.

9. A method for measuring the resistance of frozen soil according to claim 8, characterized in that: The partition member is composed of a mounting plate (4) and a labyrinth sealing sheet (41) made of elastic rubber material. The mounting plate (4) is detachably installed above the guiding frame (32). The labyrinth sealing sheet (41) is fixedly installed below the mounting plate (4). The labyrinth sealing sheet (41) extends into the gap of the guiding frame (32) and is used to partition the spiral chamber of the guiding frame (32).

10. A device for measuring the resistance of frozen soil, characterized in that, The device includes the thawing and freezing test bench described in claim 9, and further includes a frequency domain measuring device. The frequency domain measuring device is installed on the operation table (1), and the frequency domain measuring device is used to measure the soil resistivity and the unfrozen water content.

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