Tailing capillary water rising process test system and test implementation method

Abstract

The invention discloses a tailing capillary water rising process test system and a test implementation method. The bottom of a transparent glass column injected with tailing slurry is connected with a geotechnical cloth clamp, the transparent glass column is immersed into a constant water level vessel through a supporting column, the supporting column is communicated with the constant water level vessel, and the constant water level vessel is connected into a high-position water supply end through a pipeline; sensors for sensing test data of capillary water are preset at different heights of the transparent glass column and are transmitted to the processing and analyzing end in real time; observing migration characteristics of capillary water and change data of a particle microstructure by using a microscope, and transmitting the data to a processing and analyzing end in real time; and the processing and analyzing end studies the tailing capillary water from the test phenomenon in combination with the test data. The capillary water movement and tailing particle structure change can be automatically obtained and analyzed, the data accuracy and the research efficiency are improved, the manual burden is relieved, a tool is provided for tailing water migration mechanism research, and the method has wide application prospects in the fields of water conservancy projects, environmental protection and the like.

Description

Technical Field

[0001] The invention relates to a system and a test implementation method for tailings capillary water in the field of mining engineering and geotechnical engineering, and in particular to a tailings capillary water rising process test system and a test implementation method. Background Art

[0002] Tailings are important waste products after mining, and their characteristics directly affect the safety and stability of tailings dams. Tailings have significant water-sensitive properties. Especially under extreme weather conditions such as heavy rain, capillary action will rapidly increase the infiltration line, posing a serious threat to the stability of tailings dams. The stability of tailings dams depends to a large extent on the capillary phenomenon of tailings, and the long-term accumulation effect of capillary action has an extremely harmful effect on the macroscopic stability of tailings dams.

[0003] In recent years, with the extensive development of lean mines, the content of fine tailings has increased significantly, making the study of tailings capillary action more important. Although domestic and foreign scholars have conducted extensive research on soil capillary action, the research on tailings capillary action is still relatively insufficient, especially in the research gap on the changes in tailings microstructure caused by capillary action.

[0004] At present, the research on tailings capillary phenomenon mainly focuses on macroscopic factors such as particle size distribution, particle size and water content. However, there are relatively few studies on the macroscopic rise mode of capillary water and the mesoscopic structural changes of the pores between tailings particles. The development process of tailings particles from dry to wet is a key factor in causing disasters such as dam slope piping, earth flow, and swamps. Therefore, it is necessary to deeply study the mesoscopic structure such as the relative position, contact state, size and shape of the pores between tailings particles, as well as the mesoscopic mechanism of water-soil interaction.

[0005] At the same time, existing studies on tailings mesostructures mostly focus on the observation of microstructure profiles or cross-sections, and the scope and field of view of the research are relatively limited. In addition, existing observation methods such as scanning electron microscopy, ESEM, nuclear magnetic resonance and CT scanning either cannot meet the needs of long-term experiments, or the equipment is expensive and complicated to operate, which makes the observation and research of tailings capillary phenomena face certain challenges. Summary of the invention

[0006] In order to solve the shortcomings of the above-mentioned technology, the present invention provides a tailings capillary water rising process testing system and a testing implementation method.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for implementing the test of the rising process of tailings capillary water;

[0008] The bottom of the transparent glass column into which the tailings slurry is injected is connected to a geotextile fixture, the geotextile fixture is immersed in a constant water level vessel through a support column, and a water inlet and a drain are arranged on the support column to connect to the constant water level vessel, and the constant water level vessel is connected to a high-level water supply end through a pipeline;

[0009] Sensors are preset at different heights of the transparent glass column to sense the test data of capillary water, and transmit the data to the processing and analysis end in real time;

[0010] Use a microscope to observe the migration characteristics of capillary water and the change data of particle microstructure and transmit them to the processing and analysis end in real time;

[0011] The processing and analysis end studies the tailings capillary water from the test phenomena and in combination with the test data.

[0012] Furthermore, there are two transparent glass columns, which are in contrast to each other. The inner diameter of the transparent glass column is 110 mm, the height is 480 mm, and the wall thickness is 5 mm. The bottom of each transparent glass column is connected to a support column with a height of 100 mm, and the geotextile clamp is installed on the top of the support column. The input port is located at a height of 50 mm.

[0013] Furthermore, the geotextile clamp comprises a porous plate with a plurality of holes, each hole having a diameter of 3 mm, a thickness of the porous plate of 10 mm, and a geotextile having a diameter of 110 mm covering the porous plate.

[0014] Furthermore, in the test implementation method, the temperature was kept constant at 25° C. and the pressure was standard atmospheric pressure.

[0015] Further, the pre-preparation process of tailings slurry is to carry out layered sample loading and seismic compaction every 5 cm after cleaning, drying and screening the tailings samples, and place the loaded tailings samples for 24 hours.

[0016] Furthermore, there are several sensors, which are respectively installed in the reserved holes at different heights of the transparent glass column, and the gaps between the reserved holes are sealed with glass glue.

[0017] Furthermore, there are a plurality of microscopes, which are divided into two groups, and a plurality of microscopes in each group direct microscope lenses toward and align them one by one with the positions where the sensors are located at a level angle.

[0018] A test system for the capillary water rising process of tailings, the test system comprising a capillary water absorption-release experimental column group, an online moisture content monitoring system, a data and image acquisition system, a mesoscopic observation system, a water supply system and a drainage system;

[0019] The capillary water absorption and release test column set includes two transparent glass columns and a support column, which are used to observe the process of capillary water rising during the capillary water absorption and release experiment;

[0020] The online moisture content monitoring system includes a temperature and humidity sensor and a converter, which monitors the changes in the moisture content of the sample during the experiment in real time and converts it into readable data for the analysis end;

[0021] The data and image acquisition system includes a computer and a data acquisition system, wherein the data acquisition system is used to adjust, receive, transmit and store the acquired image data through the computer;

[0022] The mesoscopic observation system includes a microscope system and an image analyzer system. The microscope system uses a high-definition digital microscope and an image analyzer to observe and analyze the mesoscopic structural changes of the pores between tailings particles and the mesoscale structure during the capillary water rise process.

[0023] The water supply system includes a water source, a water storage tank and a water inlet pipe, which provides a constant water source for the experiment through the siphon principle to ensure a stable water supply during the experiment;

[0024] The drainage system includes a water outlet pipe and a water level measuring vessel, which are connected to the water storage tank to control the liquid level in the water storage tank, ensure the consistency of the experimental conditions, and facilitate the discharge of excess water after the experiment.

[0025] Furthermore, a valve is provided on the water inlet pipe.

[0026] Furthermore, the height of the outflow side of the drain pipe is flush with the highest level of the liquid surface of the water level equalizing vessel.

[0027] The present invention discloses a tailings capillary water rising process testing system and a testing implementation method, which is a tailings capillary water rising process testing system and a testing implementation method based on online monitoring technology, and has the following features:

[0028] Beneficial effects:

[0029] By combining the constant liquid level water supply method with the online monitoring sensor, various characteristics and data of the capillary water rise process can be monitored and recorded in real time, thereby greatly improving the precision and accuracy of the measurement. Compared with traditional measurement methods, it can more accurately reflect the actual situation of capillary water rise and provide more reliable data support for related research and applications.

[0030] The online monitoring technology is used to automatically acquire, process and transmit data, greatly reducing the labor intensity of manual monitoring. At the same time, since the system can monitor data in real time, abnormal situations can be discovered and handled in a timely manner, improving work efficiency and safety.

[0031] It provides a favorable tool for the study of the migration mechanism and microstructural changes of tailings capillary water. Through this system, researchers can observe and analyze various characteristics and data of the capillary water rise process in real time, so as to have a deeper understanding of the migration law and influencing factors of tailings capillary water, and provide new ideas and methods for scientific research in related fields.

[0032] It has a wide range of application prospects in actual engineering. For example, in the fields of water conservancy, civil engineering, environmental protection, etc., the system can be used to monitor groundwater levels and soil moisture in real time, providing an important reference for engineering design and construction. At the same time, the system can also be used to assess the risk and degree of groundwater pollution, providing a scientific basis for environmental protection and governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention.

[0034] Figure 2 It is the grain classification curve of tailings.

[0035] Figure 3 This is a graph showing the relationship between the wetting front of the tailings of the present invention and time in the first 500 minutes.

[0036] Figure 4 This is a graph showing the relationship between the wetting front of the tailings of the present invention and time in the first 11,000 minutes.

[0037] Figure 5 It is the relationship diagram between the water content and height of the tailings of the present invention.

[0038] Figure 6 This is the experimental migration state diagram of tailings capillary water.

[0039] Figure 7 Mesoscopic images of the capillary at different heights 1 hour after the experiment.

[0040] Figure 8 This is a mesoscopic mechanism diagram of capillary water migration in tailings.

[0041] Fig. 9 This is a diagram of the different occurrence states of tailings capillary water.

[0042] In the figure: 1. transparent glass column; 2. tailings slurry; 3. sensor; 4. RS485 converter; 5. microscope; 6. processing and analysis end; 7. water level measuring vessel; 8. water supply end; 9. water supply bracket; 10. valve; 11. water inlet pipe; 12. drain outlet; 13. support column; 14. water inlet; 15. drain pipe; 16. geotextile; 17. porous disk. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0044] Embodiment 1;

[0045] This embodiment discloses a test system for the rising process of tailings capillary water based on online monitoring technology. Before testing the system, it should be understood that the basic principle of the wetting phenomenon at the interface between liquid (such as water) and solid (such as tailings) exists. There is an extremely thin liquid film in the interface area between tailings and water, and its thickness is approximately the size of the molecular radius, which is macroscopically named as the bonding layer; when the cohesive force of the liquid exceeds the adhesive force, the combined force of the cohesive force and the adhesive force of the interface layer points to the inside of the liquid, prompting the molecules of the interface layer to squeeze into the liquid, causing the interface layer to tend to shrink, forming a convex interface and an obtuse contact angle, at which time the solid phase is not easily wetted by the liquid phase; on the contrary, if the cohesive force of the liquid is less than the adhesive force, the combined force points to the outside of the liquid, and the molecules of the interface layer are pulled toward the interface layer to gather, and the interface layer tends to expand, forming a concave interface and an acute contact angle, that is, the solid phase can be well wetted by the liquid phase. Therefore, the core of the wetting phenomenon lies in the adhesion force exceeding the cohesive force. The interaction between adjacent liquid levels is manifested as tension. Formula 1 is the basic equation for solid surface wetting, also known as the wetting equation:

[0046] γ sg =γ sl +γ gl COSθ formula 1;

[0047] In the formula, γsg, γsl and γgl [Nm -1 ] represent the interfacial tensions of solid-gas, solid-liquid and liquid-gas respectively, and θ is the contact angle.

[0048] The present invention is based on the basic principle of the wetting phenomenon at the interface between liquid and solid. The present invention discloses a test system for the rising process of tailings capillary water based on online monitoring technology. The test system includes a capillary water absorption-release experimental column group, an online moisture content monitoring system, a data and image acquisition system, a mesoscopic observation system, a water supply system and a drainage system;

[0049] The capillary water absorption and release test column set includes two transparent glass columns and a support column, which are used to observe the process of capillary water rising during the capillary water absorption and release experiment;

[0050] The online moisture content monitoring system includes a temperature and humidity sensor and a converter, which monitors the changes in the moisture content of the sample during the experiment in real time and converts it into readable data for the analysis end;

[0051] The data and image acquisition system includes a computer and a data acquisition system, wherein the data acquisition system is used to adjust, receive, transmit and store the acquired image data through the computer;

[0052] The mesoscopic observation system includes a microscope system and an image analyzer system. The microscope system observes and analyzes the mesoscopic structural changes of the pores between the tailings particles and the mesoscale structure during the capillary water rise process through a high-definition digital microscope and an image analyzer. Specifically, the high-definition digital microscope is installed through a three-dimensional mobile microscope observation frame. The microscope system includes a camera and a computer. With the help of the WIFI function, the high-definition digital microscope can transmit the continuous-tone analog image to the computer (or the mobile phone device in other embodiments) through sampling and quantization. During the observation process, the image can be adjusted, received, transmitted and stored by the computer to realize online monitoring and information processing automation. The microscope overcomes the shortcomings of the narrow focal plane of traditional microscopes, can meet the needs of long-term experiments, and is an ideal instrument for observing the mesoscale structure during the capillary rise process.

[0053] The water supply system includes a water source, a water storage tank and a water inlet pipe, which provides a constant water source for the experiment through the siphon principle to ensure a stable water supply during the experiment; the drainage system includes a water outlet pipe and a water level equalizer, which is connected to the water storage tank to control the liquid level in the water storage tank to ensure the consistency of the experimental conditions and facilitate the discharge of excess water after the experiment. Among them, a valve is set on the water inlet pipe. The height of the outflow side of the drainage pipe is flush with the highest level of the liquid surface in the water level equalizer.

[0054] Embodiment 2:

[0055] Based on the above test system, the present invention discloses a method for testing and implementing the rising process of tailings capillary water based on online monitoring technology;

[0056] like Figure 1As shown, the bottom of the transparent glass column 1 injected with tailings slurry 2 is connected to a geotextile clamp. There are two transparent glass columns, which are in contrast to each other. The inner diameter of the transparent glass column is 110 mm, the height is 480 mm, and the wall thickness is 5 mm. The bottom of each transparent glass column is connected to a support column 13 for loading and supporting the transparent glass column. The height of the support column is 100 mm to avoid the influence of the curvature of the organic glass column on the observation effect and meet the requirements of the sample size. The geotextile clamp is installed on the top of the support column, and the input port is located at a height of 50 mm. The geotextile clamp includes a porous disk with multiple holes, each of which has a hole diameter of 3 mm to ensure that water can enter the tailings. The thickness of the porous disk is 10 mm, and a geotextile 16 with a diameter of 110 mm is covered on the porous disk. Preferably, a rubber gasket can be passed between the porous disk 17 and the support column to achieve a sealing effect. The geotextile clamp is immersed in the equalizing water level vessel 7 through the support column, and a water inlet 14 and a drain port 12 are arranged on the support column 13 to connect to the equalizing water level vessel. The equalizing water level vessel is connected to the high-level water supply end 8 through the water inlet pipe 11. A valve 10 is arranged on the water inlet pipe. The water supply end 8 is raised by the water supply bracket 9, and a drain pipe 15 is connected to the equalizing water level vessel; the height of the outflow side of the drain pipe is flush with the highest level of the liquid surface of the equalizing water level vessel to ensure constant liquid level water supply of the equalizing water level vessel.

[0057] Sensors 3 for sensing capillary water test data are preset at different heights of the transparent glass column. The sensor adopts SM3001B temperature and humidity sensor. The output end of SM3001B temperature and humidity sensor passes through SU9101BRS485 converter 4 and is transmitted to processing and analysis end 6 in real time. The processing and analysis end adopts SV3010 data collector;

[0058] The migration characteristics of capillary water and the change data of the particle microstructure are observed by using the microscope 5 and transmitted to the processing and analysis end in real time; it should be understood that the microscope is used in conjunction with an image analyzer and a computer to transmit the observed change data of capillary water to the processing and analysis end;

[0059] Finally, the processing and analysis end studies the tailings capillary water from the test phenomena and combined with the test data.

[0060] Among them, the prefabrication process of tailings slurry is to carry out layered sample loading and seismic compaction every 5cm after cleaning, drying and screening tailings samples, and place the loaded tailings samples for 24 hours. In the present embodiment, the tailings slurry comes from a copper mine tailings pond located in Shaanxi Province, and the tailings particle size is between 0.5 and 350 μm, and most of them are between 100 and 200 μm. The uniformity coefficient Cu value is 6.69, and the curvature coefficient Cc value is 1.86, indicating that the particle size distribution range of the tailings is wide and the classification is good. Among them. Quartz is the main mineral component in copper tailings, accounting for 79.51%. The average pore size is 10.739 μm and the porosity is 4.91%. The pores are mainly mesopores with good connectivity. Table 1 shows the particle composition and main physical property indicators.

[0061] Table 1

[0062]

[0063] There are several sensors, which are respectively installed in the reserved holes at different heights of the transparent glass column, and the gaps between the reserved holes are sealed with glass glue. There are several microscopes, which are divided into two groups, and several microscopes in each group use a horizontal angle to face and align the microscope lenses to the positions of the sensors.

[0064] Through the whole process of capillary water absorption, the migration characteristics of capillary water and the changes in the microstructure of particles were observed. During the experiment, the temperature was kept constant at 25°C and the pressure was standard atmospheric pressure. Figure 2 As shown, the specific test steps are:

[0065] After the start, prepare experimental materials and equipment, build an online monitoring capillary water rise experimental device (or experimental system, including capillary water absorption-release experimental column group, online moisture content monitoring system, data and image acquisition system, mesoscopic observation system, water supply system and drainage system), install and debug equipment, including installing and debugging constant liquid level water supply device, install moisture content online monitoring sensor in reserved hole, and seal it with glass glue, check whether the sensor circuit works properly, install orthogonal microscope and adjust the lens, start the experiment to observe and record the capillary water rise process in real time, adjust the microscope focal length to ensure the image is clear, transfer the microscope image to computer or mobile device through WIFI function, and then analyze the data, observe the relationship between capillary water rise height and time, analyze the relationship between moisture content and rise height, observe the changes in tailings mesostructure, and finally draw experimental conclusions and end the experimental process.

[0066] At the beginning of the experiment, the plexiglass column was moved into the water level vessel, the valve on the water inlet pipe was opened, water was allowed to enter the water level vessel, and the water flow rate was controlled to ensure that the water just touched the bottom of the tailings. At the same time, the siphon principle was used to ensure that the water level in the water tank was constant, and then various characteristics and data of the capillary water rise process were observed and recorded in real time. This step ensured that the water supply could remain stable throughout the experiment, thereby avoiding interference with the experimental results due to unstable water supply.

[0067] Combined with specific experimental examples, Figure 3 The relationship between tailings wetting front and time in the first 500 minutes is shown. Figure 4 The relationship between the wetting front and time in the first 11,000 minutes of the tailings is shown. It can be seen that the height of the wetting front increases exponentially with time, showing the characteristics of rapid rise in the early stage, slow rise in the middle stage, and stable rise in the late stage. According to the changing characteristics of the capillary rise rate, the capillary rise process can be divided into three stages: rapid rise stage, slow rise stage, and stable rise stage. From a mechanical point of view, the capillary rise process is affected by the combination of capillary force, inertial force, viscous resistance and its gravity, and the main forces acting on the process vary with the stage. The first stage (AB) is the initial stage of capillary rise, which is characterized by the rapid rise of the wetting front, reaching 37.8 cm in the first 100 minutes, with an average rise rate of 17.76 cm. In the initial stage, the amount of water is very small, and the viscous resistance related to the amount of liquid and its own gravity effect can be ignored. The capillary pressure that is independent of the liquid volume and the inertial force related to the rate of change of the liquid volume jointly support the rise of capillary water. Therefore, this initial rapid rise stage is also called the pure inertial stage of the capillary rise of tailings. The second stage (BC) (100-2000 minutes) is the middle stage of capillary rise. In this stage, the capillary rise rate is relatively slow, and the amount of liquid in the capillary gradually increases with time. The relevant viscous resistance, self-gravity, inertial force and capillary driving pressure all support the flow of capillary water. Therefore, this stage is the viscous inertial stage of tailings capillary rise. The third stage (CD) is the late stage of capillary rise. The driving force of capillary pressure is getting closer and closer to the effect of viscous force and its gravity resistance, and its driving force and resistance can offset each other. The acceleration of capillary water gradually decreases, the inertial effect is weak, and the fluid flow tends to a stable Poiseuille flow. The only forces that can dominate are viscous force and capillary force, and this stage is the purely viscous stage of tailings capillary rise.

[0068] During the experiment, the change of water content during the water absorption process was observed. The relationship between the water content of the tailings and the height is shown in Figure 5As shown, it can be seen that the relationship between water content and capillary water rise height is similar to the water-soil characteristic curve in an inverse S shape. The water content ranges from 4.15% to 21.3%, with an average of 12.725% and a change of 17.15%. As the capillary water content rises, the water content gradually decreases, and the closer to the bottom, the more obvious the change in water content. The water content at the bottom of the sample is 21.3%, close to saturation.

[0069] When the soil water potential at each point in the tailings column reaches equilibrium, the total soil water potential is 0:

[0070]

[0071] in is the total soil and water potential, is the matrix potential, and z is the gravity potential. As the capillary water rises, the gravity potential increases, the matrix potential decreases, the water content decreases, and the water content of the tailings column decreases from bottom to top. By analyzing the changes in matrix absorption in the tailings column, it can be seen that matrix absorption decreases with time, with a fast initial decline rate and a gradual slowdown in the later period. This change relationship is consistent with the negative correlation between matrix suction and volumetric water content, that is, the capillary water absorption process is an uneven process.

[0072] The water transport characteristics and mesostructure of tailings capillaries, Figure 6 The microstructural images of the tailings at 18.1 cm (a scale with the top surface height of the porous disk engraved at the bottom of the transparent glass column is 0 point, and 18.1 cm is measured from the bottom to the top), after initial water absorption and after no water absorption, 0.02d (30 minutes), 0.0625d (90 minutes), 2d, 4d and 7d are shown. Figure 6 (a) shows the case where the tailings do not absorb water. It can be seen that the tailings have a single particle structure and the particle size is uniform. The color is clear and the shape is close to spherical, similar to soil particles. The tailings particles are in close contact with each other, and the contact mode is mainly vertical, thus forming a vertical columnar structure parallel to the pores. The pores are small and evenly distributed. Figure 6 (a), A represents tailings particles, B represents pores). After absorbing water for 0.02 days, the outlines of 50% of the tailings particles become blurred, such as Figure 6 (b) As shown in the left part, the color becomes darker, the particle outline cannot be clearly identified, and a water film C appears between the particles. Figure 6 (b). This is mainly because the microstructure of the tailings is conducive to the formation of capillaries, which causes the capillary water to rise rapidly under the influence of water surface tension. Under low saturation conditions, short-range adsorption forms a very thin water film on the surface of the tailings particles. After 0.0625 days of water absorption, part of the pores are filled with water, and the overall color of the image becomes darker than the initial image. Figure 6(a), undischarged gas D, Figure 6 (c), it can be seen between the macropores, which are in the form of discontinuous bubbles. Therefore, a complex solid, liquid and gas phase is formed. After 2 days of water absorption, the large bubbles are connected to each other to form a continuous dendritic bubble belt, such as Figure 6 (d) shows that it is pale white and occupies most of the pore area. At the same time, capillary water continues to migrate upward. After 4 days of water absorption, Figure 6 The left part of (e) is almost completely filled with water. Figure 6 Compared with (d), the capillary water connection area is larger, but there is still a small part of the capillary disconnection phenomenon F. This is because the bubble belt forms a closed loop, which produces blind holes that hinder the migration of capillary water. After 7 days of water absorption, Figure 6 (f), the bubble area is darker and more obvious than the former, and occupies a smaller proportion of the entire area. Figure 6 (f) The capillary connectivity in region G increases, but there is still unreleased gas. Figure 6 (a)-6(f) It can be seen that the color of the tailings and the number of bubbles indicate that the migration of capillary water is a dynamic process both vertically and horizontally.

[0073] Figure 7 The image was collected 1 hour after the experiment. It is a mesoscopic image of the capillary at different heights. In the figure, micrographs of tailings at different heights (×50 times): (a) 10cm, (b) 20cm, (c) 30cm, (d) 40cm, (e) 50cm, (f) 60cm; it can be seen that as the capillary water rises, the water between particles gradually decreases, and the state of the particles changes from wet to wet, which also reflects the law of gradually decreasing water content.

[0074] Therefore, during the capillary rise process, the microstructure of the tailings is also changing, and the most significant change is the distribution of water content in the pores. As the capillary water migrates upward from the smaller pores, it takes away some of the gas. When the microstructure of the tailings stabilizes, there is still gas in the tailings, eventually forming a complex solid-liquid-gas three-phase system.

[0075] The mesoscopic mechanism of capillary water migration in tailings, the pore structure plays a decisive role in the physical and mechanical properties of saturated and unsaturated tailings, especially unsaturated tailings. According to the pore size, pores can be divided into micropores, mesopores and macropores. Micropores refer to pores with a diameter less than 0.1 microns, and the water in the pores is mainly adsorbed water. Mesopores refer to pores with a diameter between 0.1-1000 microns, and the water in the pores is mainly capillary water, and there is also some gravity water in the pores close to the macropores. Macropores refer to pores with a pore diameter greater than 1000 microns, and the water in the pores is mainly gravity water, and its migration process follows Darcy's law. In addition, almost all mineral particles have a water film bound to their surfaces, and the water close to the surface of the mineral particles is strongly bound water. As its binding force with water weakens, it gradually becomes weakly bound water and finally becomes free water (the mechanism of action is shown in Figure 8 In the figure, the capillary water absorption process of tailings is shown respectively: (a) initial state, (b) starting point, (c) macropore and mesopore water absorption, and (d) micropore water absorption).

[0076] After water absorption, the main driving force for water migration in tailings is capillary force. Since most of the air inside the tailings is discharged during the layered compaction process, the initial capillary water rises faster and can rise to 9 cm in the first 60 seconds. In the early stage of water absorption, macropores and mesopores are quickly filled with water, mainly mesopores. As the saturation slowly increases, water gradually enters the micropores.

[0077] Capillary action is very microscopic, and its mechanism belongs to the action of intermolecular forces. The size of molecules is only 0.1nm, and the distance between molecules is also only 0.1nm, so the origin of its action is microscopic. The thickness of the bound water film is very thin and accounts for a small proportion of the total water content, but it has an important influence on the physical and mechanical properties of the soil.

[0078] Continuous capillary water absorption experiments show that there are obvious differences in the mesostructure of tailings with different water contents. Fig. 9 It is the change in the shape of the liquid bridge after the capillary rise of the tailings is completed. Once the water content is less than the plastic limit of the tailings (such as 8%), there are mainly pendulum-shaped and rope-shaped liquid bridges between the particles. Fig. 9 (a) and 12 (b). The liquid bridge is slender, and the pores are mainly composed of point contacts between particles. The pores are mainly composed of point contacts between particles, and the tailings are solid and semi-solid. When the water content is greater than the plastic limit (such as 18.8%), the liquid bridge between particles gradually changes from annular to capillary. Fig. 9(c). As some particles are filled with water, the proportion of pores between particles filled with liquid increases, and the tailings exist in a viscous state around the contact points. It can be seen that the color of the image collected by the microscope begins to darken, the structure of individual tailings particles becomes blurred, the adhesion between particles becomes stronger, and the structure gradually transforms into a small structure formed by water-adhesive particles. When the water content is greater than the liquid limit (such as 21%), the pores between the particles are filled with free water, and the liquid bridges are mainly capillaries. Individual particles can no longer be clearly observed, and some particles exist in the form of slurry. Fig. 9 (d) The pores are mainly gaps in the cohesive block structure.

[0079] The final conclusion is that the capillary water rising process of tailings shows an obvious three-stage downward trend according to the change of flow rate, which can be divided into the early rapid rising stage, the mid-term slow rising stage and the late stable rising stage. In the first 100 minutes of the experiment, the rising height reached 37.8 cm, accounting for 58% of the total rising height, and the average rising speed was 17.76 cm per hour. Capillary water absorption is a non-uniform water absorption process. With the increase of the capillary water rising height, the water content gradually decreases, and its change curve is an inverted S shape, with a water content range of 4.15%-21.3%. Moreover, the closer to the bottom, the more obvious the change in water content. The mesostructure of tailings with different water contents has obvious differences in particle morphology, particle connection mode, pore state and liquid bridge morphology. The most obvious change is the occurrence form of water in the pores. The capillary action of tailings follows the order of macropores → mesopores → micropores to absorb water, and water absorption mainly occurs in mesopores. The change of saturation from low to high results in different occurrence states of water between particles, which manifests as pendulum-shaped, ring-shaped, capillary-shaped and slurry-shaped liquid bridges.

[0080] In summary, the beneficial effects of the present invention are:

[0081] (1) The present invention combines the constant liquid level water supply mode with the online monitoring sensor to monitor and record various characteristics and data of the capillary water rise process in real time, thereby greatly improving the measurement precision and accuracy. Compared with the traditional measurement method, it can more accurately reflect the actual situation of capillary water rise and provide more reliable data support for related research and application.

[0082] (2) The present invention adopts online monitoring technology, which can automatically acquire, process and transmit data, greatly reducing the labor intensity of manual monitoring. At the same time, since the system can monitor data in real time, abnormal situations can be discovered and handled in time, improving work efficiency and safety.

[0083] (3) The present invention provides a powerful tool for studying the migration mechanism and microstructural changes of tailings capillary water. Through this system, researchers can observe and analyze various characteristics and data of the capillary water rise process in real time, thereby gaining a deeper understanding of the migration law and influencing factors of tailings capillary water, and providing new ideas and methods for scientific research in related fields.

[0084] (3) The present invention has broad application prospects in practical engineering. For example, in the fields of water conservancy, civil engineering, environmental protection, etc., the system can be used to monitor groundwater levels, soil moisture content, etc. in real time, providing an important reference basis for engineering design and construction. At the same time, the system can also be used to assess the risk and degree of groundwater pollution, providing a scientific basis for environmental protection and governance. The above implementation methods are not limitations of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also belong to the protection scope of the present invention.

Claims

1. A method for testing the rising process of tailings capillary water, characterized in that: The bottom of the transparent glass column into which the tailings slurry is injected is connected to a geotextile fixture, the geotextile fixture is immersed in a constant water level vessel through a support column, and a water inlet and a drain are arranged on the support column to connect to the constant water level vessel, and the constant water level vessel is connected to a high-level water supply end through a pipeline; Sensors are preset at different heights of the transparent glass column to sense the test data of capillary water, and transmit the data to the processing and analysis end in real time; Use a microscope to observe the migration characteristics of capillary water and the change data of particle microstructure and transmit them to the processing and analysis end in real time; The processing and analysis end studies the tailings capillary water from the test phenomena and in combination with the test data.

2. The tailings capillary water rising process test implementation method according to claim 1, characterized in that: There are two transparent glass columns, which are in contrast to each other. The inner diameter of the transparent glass column is 110 mm, the height is 480 mm, and the wall thickness is 5 mm. The bottom of each transparent glass column is connected to a support column with a height of 100 mm, and the geotextile clamp is installed on the top of the support column. The input port is located at a height of 50 mm.

3. The tailings capillary water rising process test implementation method according to claim 2 is characterized in that: The geotextile clamp comprises a porous plate with a plurality of holes, each hole having a diameter of 3 mm, a thickness of the porous plate of 10 mm, and a geotextile with a diameter of 110 mm covering the porous plate.

4. The method for implementing the test of tailings capillary water rising process according to claim 1, characterized in that: The temperature during the test was kept constant at 25°C and the pressure was standard atmospheric pressure.

5. The method for testing the tailings capillary water rising process according to claim 1, wherein: The prefabrication process of the tailings slurry is to carry out layered sample loading and seismic compaction every 5 cm after cleaning, drying and screening the tailings samples, and place the loaded tailings samples for 24 hours.

6. The method for testing the tailings capillary water rising process according to claim 1, characterized in that: There are several sensors, which are respectively installed in the reserved holes at different heights of the transparent glass column, and the gaps between the reserved holes are sealed with glass glue.

7. The method for testing the tailings capillary water rising process according to claim 1, characterized in that: There are a plurality of microscopes, which are divided into two groups. The microscopes in each group use a horizontal angle to direct microscope lenses toward and align them one by one with the positions where the sensors are located.

8. A testing system for the capillary water rising process of tailings, characterized by: The test system includes a capillary water absorption-release experimental column group, an online water content monitoring system, a data and image acquisition system, a mesoscopic observation system, a water supply system and a drainage system; The capillary water absorption-release test column set includes two transparent glass columns and a support column, which are used to observe the process of capillary water rising during the capillary water absorption-release experiment; The online moisture content monitoring system includes a temperature and humidity sensor and a converter, which monitors the moisture content changes of the sample during the experiment in real time and converts them into readable data at the analysis end; The data and image acquisition system includes a computer and a data acquisition system, and the data acquisition system is used to adjust, receive, transmit and store the acquired image data through the computer; The mesoscopic observation system includes a microscope system and an image analyzer system. The microscope system observes and analyzes the mesoscopic structural changes of the pores between the tailings particles and the mesoscale structure during the capillary water rise process through a high-definition digital microscope and an image analyzer. The water supply system includes a water source, a water storage tank and a water inlet pipe, which provides a constant water source for the experiment through the siphon principle to ensure a stable water supply during the experiment; The drainage system includes a water outlet pipe and a water level measuring vessel, which are connected to the water storage tank to control the liquid level in the water storage tank, thereby ensuring the consistency of experimental conditions and facilitating the discharge of excess water after the experiment.

9. The testing system for the tailings capillary water rising process according to claim 8, characterized in that: The water inlet pipe is provided with a valve.

10. The testing system for the tailings capillary water rising process according to claim 8, characterized in that: The height of the outflow side of the drain pipe is flush with the highest level of the liquid surface in the water level equalizing vessel.

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