Visual test device and method for cohesionless soil seepage erosion process

Abstract

The invention discloses a visual test device and method for a cohesionless soil seepage erosion process, and the device comprises a water head control and fluid circulation system, an erosion loss particle separation and weighing system, and a digital image and data collection system, the water head control and fluid circulation system comprises an upstream liquid storage tank located on a lifting platform, the upstream liquid storage tank is connected with the permeation device through a pipeline, the permeation device is connected with the erosion loss particle separating and weighing system through a pipeline, the downstream liquid storage tank is connected with the peristaltic pump through a pipeline, and the peristaltic pump is connected with the upstream liquid storage tank through a pipeline; the erosion loss particle separating and weighing system is used for collecting erosion loss fine particles and recording mass change in real time; the digital image and data acquisition system is used for recording pressure and flow data and acquiring pore structure characteristic parameters in combination with image processing; according to the method, the limitation that seepage change in the soil body is difficult to monitor in real time is overcome, and the change rule of the soil body pore structure under the cohesionless soil seepage erosion effect can be obtained.

Description

Technical Field

[0001] This invention relates to the fields of water conservancy engineering and geotechnical engineering technology, and in particular to a visual experimental device and method for the seepage erosion process of non-cohesive soil. Background Technology

[0002] Seepage erosion refers to the migration of soil particles under the influence of seepage, which can lead to soil seepage damage such as piping and soil erosion. Seepage erosion causes fine particles in the foundation soil to be carried away by the water flow, increasing the soil's porosity, reducing its density, and significantly decreasing its bearing capacity. In slope engineering, seepage increases the soil's self-weight while reducing the cohesion and internal friction angle between soil particles, thus lowering the slope's anti-sliding stability. This can potentially cause landslides, collapses, and other disasters, damaging engineering facilities.

[0003] Cohesionless soil particles exhibit weak interparticle bonding, making them prone to particle migration and pore remodeling under seepage. Their seepage erosion process is dynamic, microscopic, and complex. Limited by the soil's opacity and the limitations of current observation techniques, traditional experimental methods struggle to penetrate the soil surface, failing to capture minute changes in local pores or quantify the overall pore structure remodeling trend. Consequently, the coupling mechanism between pore structure changes and seepage erosion remains largely unresolved. Faced with this technical predicament, traditional seepage tests rely on macroscopic parameters (such as average flow velocity, hydraulic gradient, permeability coefficient, and volumetric water content) to indirectly infer the changes in the soil's internal structure. However, inferences about soil structure changes based on macroscopic parameters contain significant uncertainties, making it difficult to accurately characterize the evolution and essential laws of the soil's internal microstructure under seepage. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a visual experimental device and method for the seepage erosion process of cohesive soil, overcoming the limitation of difficulty in real-time monitoring of seepage changes inside the soil, so as to obtain the change law of soil pore structure under the action of seepage erosion of cohesive soil.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a visualization test device for the seepage erosion process of cohesive soil, comprising a head control and fluid circulation system, an erosion particle separation and weighing system, and a digital image and data acquisition system. The head control and fluid circulation system includes an upstream storage tank located on a lifting platform. The upstream storage tank is connected to a permeation device via a pipeline. The permeation device is connected to the erosion particle separation and weighing system via a pipeline. The downstream storage tank is connected to a peristaltic pump via a pipeline. The peristaltic pump is connected to the upstream storage tank via a pipeline. The erosion particle separation and weighing system is used to collect the eroded fine particles, record the mass change in real time, and realize dynamic tracking of the erosion rate. The digital image and data acquisition system is used to record pressure and flow data, and obtain pore structure characteristic parameters by combining image processing.

[0006] Preferably, the infiltration device comprises three areas: a diffusion layer, a transparent sample chamber, and a liquid collection chamber. The diffusion layer is located at the bottom, filled with gravel, and isolated from the upper layer by a porous filter plate, with a seepage inlet at the bottom. The transparent sample chamber is located in the middle area, where a transparent soil sample is placed. A porous filter plate and nylon mesh are laid at the bottom to prevent the loss of fine particles, and a rectangular seepage outlet is provided at the top. The liquid collection chamber is located at the top and is used to collect sand-containing fluid and transport it to the erosion and loss particle separation and weighing system. A planar laser emitter is provided on the side of the infiltration device. The planar laser emitted by the emitter is used to irradiate the transparent soil sample in the transparent sample chamber to excite fluorescence observation of the soil sample particle distribution in the irradiated plane, thereby realizing the visual observation of the seepage erosion process.

[0007] Preferably, the upstream storage tank includes an overflow tank and a pressure stabilizing tank, with an L-shaped partition between the overflow tank and the pressure stabilizing tank. The bottom of the overflow tank has an overflow tank outlet, and the bottom of the pressure stabilizing tank has a pressure stabilizing tank inlet and a pressure stabilizing tank outlet. The downstream storage tank has a downstream storage tank inlet and a downstream storage tank outlet, and its top is an open structure.

[0008] Preferably, the outlet of the pressure stabilizing tank is connected to the inlet of the permeation device through a first pipe, and the inlet of the pressure stabilizing tank is connected to the outlet of the downstream storage tank through a second pipe; the outlet of the overflow tank is connected to the inlet of the downstream storage tank through a third pipe; the outlet of the liquid collection chamber of the permeation device is connected to one end of a fourth pipe, and the other end of the fourth pipe is connected to the erosion and loss particle separation and weighing system.

[0009] Preferably, the upstream storage tank is placed on a lifting platform, which is higher than the permeation device; the peristaltic pump is located on the second pipeline and is used to pump the solution in the downstream storage tank to the upstream storage tank to achieve fluid circulation.

[0010] Preferably, the particle separation and weighing system includes a support column, a high-precision electronic balance, a basket, and an iron frame; the support column is located outside the downstream storage tank, the high-precision electronic balance is placed on top of the support column, the top of the iron frame is connected to a fourth pipe, the basket is suspended below the high-precision electronic balance, located between the opening of the downstream storage tank and the end of the fourth pipe, to intercept the seeping out particles, and the suspension component of the basket is connected to the tray on the high-precision electronic balance.

[0011] Preferably, the top of the iron frame is provided with a clamp for fixing the position of the fourth pipe, and the height of the clamp is adjustable; the high-precision electronic balance is connected to the computer via a data cable; and the inside of the basket is lined with a layer of fine nylon netting.

[0012] Preferably, the image and data acquisition system includes a CCD camera, a flow meter (10), a pressure sensor (9), and a data acquisition card (11); the CCD camera (12) is located directly in front of the infiltration device and is used to capture the seepage erosion process; the flow meter and pressure sensor are located on the first pipe and are connected to the data acquisition card via a data cable, and the data acquisition card is connected to a computer via a data cable.

[0013] The present invention also discloses a test method for the above-mentioned visualization test device for the seepage erosion process of cohesive soil, which includes the following steps: Step 1: Place the prepared transparent soil sample into the transparent sample chamber of the permeation device, and install and adjust the relative positions of the CCD camera and the planar laser emitter with the transparent sample chamber; Step 2: Check the pipeline sealing. After confirming that there are no problems, connect the upstream storage tank, flow meter, pressure sensor, infiltration device, downstream storage tank and peristaltic pump in sequence to purge the gas in the first pipeline. Adjust the height of the lifting platform so that the upstream storage tank provides a suitable water head for the transparent soil sample. Step 3: Adjust the relative positions of the iron frame and support column with the downstream liquid storage tank, install the basket below the high-precision electronic balance, place the high-precision electronic balance above the support column, and adjust the end of the fourth outflow pipe to be above the basket. Step 4: Connect the flow meter and pressure sensor to the data acquisition card, and connect the CCD camera, acquisition card, and high-precision electronic balance to the computer; Step 5: Turn on the main switch of the laser controller, rotate the power adjustment knob to adjust the laser to a suitable power, turn on the CCD camera and computer, check the real-time image captured by the camera, and adjust the focal length, position and exposure intensity of the CCD camera. Step 6: Record the seepage erosion and damage process inside the transparent soil sample by controlling the photo interval using a computer, and automatically store the captured images and test data; Step 7: Turn on the peristaltic pump to begin the test.

[0014] Furthermore, step 7 specifically involves the following process: Under the action of the peristaltic pump, the liquid in the downstream storage tank is discharged through the outlet of the downstream storage tank, and then introduced into the upstream storage tank through the inlet of the pressure stabilizing tank through the second pipe. When the liquid in the pressure stabilizing tank begins to overflow, the valve is opened, and the liquid in the pressure stabilizing tank is introduced into the permeation device through the outlet of the pressure stabilizing tank through the first pipe. Under the action of permeation, the liquid and the corroded fine particles in the permeation device are introduced into the basket through the collection chamber through the fourth pipe. The fine particles flow into the basket for weighing, and the liquid flows through the basket into the downstream storage tank. The liquid in the overflow tank is introduced into the inlet of the downstream storage tank through the outlet of the overflow tank through the third pipe, realizing a closed loop of fluid.

[0015] Beneficial effects of this invention: 1. The experimental apparatus and method provided by the present invention can realize the visual observation of the seepage erosion process of cohesive soil, and can record the migration of micro-particles and the evolution of pore structure in real time. The experimental results obtained can be directly used to reveal the micro-mechanism of seepage erosion of cohesive soil.

[0016] 2. This invention uses a digital image and data acquisition system to acquire images of microscopic pore structure changes during the seepage erosion process in real time, effectively solving the technical problem of difficulty in observing the internal structure of pores in traditional geotechnical tests, and realizing visualized monitoring of the entire seepage erosion process.

[0017] 3. The present invention employs an erosion particle separation and weighing system to automatically separate and weigh the lost particles in the oil-water mixture during the seepage process, ensuring the accuracy and reliability of the seepage erosion test results.

[0018] 4. This invention can overcome the limitation of difficulty in real-time monitoring of seepage changes inside soil, so as to obtain the change law of soil pore structure under seepage erosion of non-cohesive soil.

[0019] 5. In this invention, the overflow tank and the pressure stabilizing tank of the upstream liquid storage tank are separated by an L-shaped partition. The overflow tank can discharge excess liquid in time, while the pressure stabilizing tank can maintain stable internal liquid pressure, ensuring a constant fluid head delivered to the downstream permeation device, and providing stable hydraulic conditions for the experiment. The dual-port design at the bottom of the downstream liquid storage tank, combined with the open structure at the top, facilitates the reception of liquid from different pipelines and provides convenience for the connection with the separation and weighing system for erosion and loss particles. The overall structural design is reasonable, ensuring smooth fluid circulation and stable experimental conditions. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a visualization test device for the seepage erosion process of cohesive soil; Figure 2 yes Figure 1 A structural diagram from a rear view; Figure 3 yes Figure 1 A structural diagram from another frontal perspective; Figure 4 A schematic diagram of the internal structure of the upstream liquid storage tank after the top cover has been removed; Figure 5 It is a schematic diagram of the changes in the internal structure of soil during the seepage erosion process, obtained through a digital image and data acquisition system; Figure 6 This is a graph showing the cumulative loss of fine particles over time during the seepage erosion process; Figure 7 This is a graph showing the cumulative loss of fine particles and the average seepage velocity during the seepage erosion process as the hydraulic gradient changes. In the attached diagram: 1. Upstream storage tank; 2. Downstream storage tank; 3. Permeation device; 4. Planar laser emitter; 5. Lifting platform; 6. High-precision electronic balance; 7. Basket; 8. Peristaltic pump; 9. Pressure sensor; 10. Data acquisition card; 11. Flow meter; 12. CCD camera; 13. Iron frame; 14. First pipe; 15. Second pipe; 16. Third pipe; 17. Fourth pipe; 101. Overflow tank; 102. Pressure stabilizing tank; 301. Diffusion layer; 302. Transparent sample loading chamber; 303. Collection chamber; 1011. Overflow tank outlet; 1021. Pressure stabilizing tank inlet; 1022. Pressure stabilizing tank outlet; 201. Downstream storage tank inlet; 202. Downstream storage tank outlet. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Example 1: As Figures 1 to 7As shown, a visualization test device for the seepage erosion process of cohesionless soil includes a head control and fluid circulation system, an erosion particle separation and weighing system, and a digital image and data acquisition system. The head control and fluid circulation system includes an upstream storage tank 1 located on a lifting platform 5. The upstream storage tank 1 is connected to a permeation device 3 via a pipeline. The permeation device 3 is connected to the erosion particle separation and weighing system via a pipeline. A downstream storage tank 2 is connected to a peristaltic pump 8 via a pipeline. The peristaltic pump 8 is connected to the upstream storage tank 1 via a pipeline. The erosion particle separation and weighing system is used to collect the eroded fine particles, record mass changes in real time, and achieve dynamic tracking of the erosion rate. The digital image and data acquisition system is used to record pressure and flow data, and obtain pore structure characteristic parameters through image processing. This embodiment integrates the head control and fluid circulation system, the erosion particle separation and weighing system, and the digital image and data acquisition system to construct a complete test system for seepage erosion of cohesionless soil. The head control and fluid circulation system ensured a stable supply and recycling of fluids during the experiment. The erosion particle separation and weighing system collected fine particles in real time and recorded mass changes, enabling dynamic tracking of the erosion rate. The digital imaging and data acquisition system simultaneously recorded pressure and flow data and acquired pore structure characteristic parameters. The synergistic effect of these three systems overcame the limitations of traditional experiments in real-time monitoring of seepage changes within the soil, successfully achieving comprehensive capture of key parameters during the seepage erosion of cohesionless soils, and providing a reliable experimental basis for understanding the laws governing changes in soil pore structure.

[0023] Preferably, the infiltration device 3 includes three areas: a diffusion layer 301, a transparent sample chamber 302, and a liquid collection chamber 303. The diffusion layer 301 is located at the bottom, filled with gravel, and isolated from the upper layer by a porous filter plate. A seepage inlet is provided at the bottom. The transparent sample chamber 302 is located in the middle area, where a transparent soil sample is placed. A porous filter plate and nylon net are laid at the bottom to prevent the loss of fine particles. A rectangular seepage outlet is provided at the top. The liquid collection chamber 303 is located at the top and is used to collect sand-containing fluid and transport it to the erosion loss particle separation and weighing system. A planar laser emitter (4) is provided on the side of the infiltration device 3. The planar laser emitted by the emitter is used to irradiate the transparent soil sample in the transparent sample chamber 302 to excite fluorescence observation of the distribution of soil particles in the irradiated plane, thereby realizing the visual observation of the seepage erosion process. In this embodiment, the sample size is 100mm × 20mm × 140mm (length × width × height). A porous filter plate with a 4mm pore size is laid at the bottom, and a nylon mesh with a 0.25mm pore size is laid on top of the filter plate to prevent fine particles from being lost. A rectangular seepage outlet with dimensions of 100mm × 15mm is opened at the top of the sample. The diffusion layer is filled with 50mm thick 10-20mm gravel. The three-section structure of the infiltration device (diffusion layer, transparent sample chamber, and collection chamber) has a clear division of labor. The diffusion layer, through gravel filling and porous filter plate design, ensures uniform infiltration. The porous filter plate and nylon mesh in the transparent sample chamber effectively prevent premature loss of fine particles and provide a stable placement space for the transparent soil sample. The collection chamber enables efficient collection and transportation of sand-containing fluids. Crucially, the planar laser emitter on the side can excite fluorescence. Combined with the transparency of the transparent sample chamber, the distribution of soil particles in the irradiated plane can be directly observed, truly realizing the visualization of the seepage erosion process. This solves the technical problem that traditional tests cannot penetrate the soil surface and are difficult to capture particle migration and pore changes, providing a direct observation method for revealing the microscopic mechanism of seepage erosion.

[0024] Preferably, the upstream storage tank 1 includes an overflow tank 101 and a pressure stabilizing tank 102, with an L-shaped partition between them. The overflow tank 101 has an overflow outlet 1011 at its bottom, and the pressure stabilizing tank 102 has a pressure stabilizing inlet 1021 and a pressure stabilizing outlet 1022 at its bottom. The downstream storage tank 2 has a downstream storage tank inlet 201 and a downstream storage tank outlet 202, and its top is open. In this embodiment, the upstream storage tank 1 has dimensions of 190mm × 190mm × 200mm (length × width × height). The overflow tank and the pressure stabilizing tank of the upstream liquid storage tank are separated by an L-shaped partition. The overflow tank can discharge excess liquid in time, while the pressure stabilizing tank can maintain stable internal liquid pressure, ensuring a constant fluid head delivered to the downstream permeation device and providing stable hydraulic conditions for the experiment. The dual-port design at the bottom of the downstream liquid storage tank, combined with the open structure at the top, facilitates the receipt of liquid from different pipelines and provides convenience for the connection with the separation and weighing system for erosion and loss particles. The overall structural design is reasonable, ensuring smooth fluid circulation and stable experimental conditions.

[0025] Preferably, the outlet 1022 of the pressure stabilizing tank is connected to the inlet of the permeation device 3 via a first pipe 14; the inlet 1021 of the pressure stabilizing tank is connected to the outlet 202 of the downstream storage tank via a second pipe 15; the outlet 1011 of the overflow tank is connected to the inlet 201 of the downstream storage tank via a third pipe 16; and the outlet of the collection chamber 303 of the permeation device 3 is connected to one end of a fourth pipe 17 (e.g., ...). Figure 2 As shown, the outlet of the liquid collection chamber 303 is connected to the water receiving hopper at the top of the fourth pipe 17, allowing the liquid from the liquid collection chamber 303 to directly enter the water receiving hopper and then into the fourth pipe 17. The other end of the fourth pipe 17 is connected to the erosion and loss particle separation and weighing system. In this embodiment, a valve is provided on the first pipe 14 to control the opening and closing of the liquid channel. This embodiment constructs a clear and orderly fluid transmission path by clarifying the connection relationships between each pipe and the storage tank and the permeation device. The first pipe, connecting the outlet of the pressure stabilizing tank to the inlet of the permeation device, ensures the seepage introduction under a stable head. The second and third pipes respectively realize the fluid return between the downstream storage tank and the upstream storage tank pressure stabilizing tank and overflow tank. Together with the connecting pipes of the permeation device and the particle separation system, a complete fluid transmission network is formed, ensuring the orderly connection of each link such as head control, seepage erosion, and particle collection, and ensuring the continuity and stability of the experimental process.

[0026] Preferably, the upstream storage tank 1 is placed on the lifting platform 5, which is higher than the permeation device 3; the peristaltic pump 8 is located on the second pipe 15 and is used to pump the solution in the downstream storage tank 2 to the upstream storage tank 1 to achieve fluid circulation. In this embodiment, the upstream storage tank is placed on the lifting platform higher than the permeation device, which uses gravity to assist the fluid to flow smoothly to the permeation device. The height of the lifting platform can be flexibly adjusted, which facilitates precise control of the water head according to the experimental requirements. The peristaltic pump on the second pipe realizes the efficient pumping of liquid from the downstream storage tank to the upstream storage tank, and constructs a closed fluid circulation system. This not only reduces fluid waste, but also maintains the consistency of the fluid environment during the experiment, ensures the stability and continuity of the experimental conditions, and improves the reliability of the experimental results.

[0027] Preferably, the particle separation and weighing system includes a support column, a high-precision electronic balance 6, a hanging basket 7, and an iron frame 13. The support column is located outside the downstream storage tank 2, the high-precision electronic balance 6 is placed on top of the support column, the top of the iron frame 13 is connected to the fourth pipe 17, and the hanging basket 7 is suspended below the high-precision electronic balance 6, located between the opening of the downstream storage tank 2 and the end of the fourth pipe 17, to intercept seepage particles. The suspension component of the hanging basket 7 is connected to the tray on the high-precision electronic balance 6. The particle separation and weighing system of this embodiment has a highly targeted structural design. The iron frame can fix the position of the fourth pipe, ensuring that the sand-containing fluid flows accurately into the hanging basket. The hanging basket, suspended below the high-precision electronic balance, can efficiently intercept seepage fine particles, and through the direct connection between the balance and the hanging basket, it can capture the mass change of fine particles in real time. This system realizes the automatic separation and real-time weighing of eroded particles, avoiding errors in the traditional particle collection and weighing process, providing accurate data support for dynamically tracking the erosion rate, and improving the accuracy of the test results.

[0028] Preferably, the top of the iron frame 13 is provided with a clamp for fixing the position of the fourth pipe 17, and the height of the clamp is adjustable; the high-precision electronic balance 6 is connected to the computer via a data cable; and a layer of fine nylon mesh is laid inside the basket 7. The adjustable clamp of the iron frame can flexibly adjust the position and height of the fourth pipe according to the test requirements, ensuring that the sand-containing fluid flows steadily into the basket and avoiding particle splashing or loss; the connection between the high-precision electronic balance and the computer realizes the automatic transmission and storage of mass data, reducing the error of manual recording; the fine nylon mesh laid inside the basket further improves the interception effect of fine particles, prevents fine particles from passing through the basket and ensuring the authenticity and integrity of the weighing data, providing a reliable guarantee for the accurate calculation of the erosion rate.

[0029] Preferably, the image and data acquisition system includes a CCD camera 12, a flow meter 10, a pressure sensor 9, and a data acquisition card 11. The CCD camera 12 is located directly in front of the seepage device 3 and is used to capture the seepage erosion process. The flow meter 10 and pressure sensor 9 are located on the first pipe 14 and are connected to the data acquisition card via a data cable. The data acquisition card 11 is connected to a computer via a data cable. In this embodiment, the CCD camera, located directly in front of the seepage device, can clearly capture the entire seepage erosion process. Combined with the fluorescence effect excited by a planar laser, it can completely record the visual information of particle migration and pore evolution within the soil. The flow meter and pressure sensor on the first pipe can collect flow and pressure data in real time during the seepage process and transmit them to the computer via the data acquisition card, realizing automated and precise acquisition of experimental data. This system combines image information with quantitative data, which not only intuitively presents the microscopic process of seepage erosion but also provides comprehensive data support for subsequent analysis of the correlation between pore structure characteristic parameters and seepage parameters, effectively solving the problem that traditional experiments are difficult to quantify the pore structure reconstruction trend.

[0030] Example 2: A test method for a visualization test device for the seepage erosion process of cohesive soil, comprising the following steps: Step 1: Place the prepared transparent soil sample into the transparent sample chamber 302 of the permeation device 3, and install and adjust the relative positions of the CCD camera 12 and the planar laser emitter 4 with the transparent sample chamber 302. Step 2: Check the pipeline sealing. After confirming that there are no problems, connect the upstream storage tank 1, flow meter 11, pressure sensor 9, infiltration device 3, downstream storage tank 2 and peristaltic pump 8 in sequence to discharge the gas in the first pipeline 14. Adjust the height of the lifting platform 5 so that the upstream storage tank 1 provides a suitable water head for the transparent soil sample. Step 3: Adjust the relative positions of the iron frame 13 and the support column with the downstream liquid storage tank 2, install the basket 7 below the high-precision electronic balance 6, place the high-precision electronic balance 6 above the support column, and adjust the end of the outflow fourth pipe 17 to be above the basket 7. Step 4: Connect the flow meter 11 and pressure sensor 9 to the data acquisition card 10, and connect the CCD camera 12, the acquisition card 10 and the high-precision electronic balance 6 to the computer; Step 5: Turn on the main switch of the laser controller, rotate the power adjustment knob to adjust the laser to a suitable power, turn on the CCD camera 12 and the computer, check the real-time image captured by the camera, and adjust the focal length, position and exposure intensity of the CCD camera. Step 6: Record the seepage erosion and damage process inside the transparent soil sample by controlling the photo interval using a computer, and automatically store the captured images and test data; Step 7: Turn on the peristaltic pump 8 to begin the test. This embodiment's entire method revolves around a visual experimental device design, fully leveraging the synergistic effects of each system within the device to ensure stable acquisition of image data, particle mass data, and fluid parameter data during the seepage erosion process. This provides a repeatable and operable experimental procedure to support the systematic analysis of the pore structure changes in cohesive soils.

[0031] Furthermore, step 7 specifically involves the following process: Under the action of peristaltic pump 8, the liquid in downstream storage tank 2 is discharged through downstream storage tank outlet 202, and then introduced into upstream storage tank 1 through second pipe 15 and pressure stabilizing tank inlet 1021. When the liquid in pressure stabilizing tank 102 begins to overflow, the valve is opened, and the liquid in pressure stabilizing tank 102 is introduced into permeation device 3 through first pipe 14 through pressure stabilizing tank outlet 1022. Under the action of permeation, the liquid and eroded fine particles in permeation device 3 are introduced into basket 7 through fourth pipe 17 through collection chamber 303. Fine particles flow into basket 7 for weighing, and liquid flows into downstream storage tank 2 through basket 7. The liquid in overflow tank 101 is introduced into downstream storage tank inlet 201 through third pipe 16 through overflow tank outlet 1011, realizing a closed loop of fluid. This step details the fluid circulation path throughout the experimental setup. Driven by a peristaltic pump, a stable flow of liquid from the downstream storage tank to the upstream storage tank is achieved. The overflow design of the pressure stabilizing tank ensures stable head. The transmission path of the sand-laden fluid through the infiltration device and the fourth pipe to the basket ensures effective interception and weighing of fine particles. The design of liquid return through the basket and overflow tank to the downstream storage tank forms a complete closed loop. This circulation process not only ensures a continuous supply and recycling of fluid during the experiment but also maintains the stability of the experimental environment, ensuring the continuous seepage erosion process and providing a reliable process guarantee for obtaining consistent and accurate experimental data.

[0032] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A visualization experimental device for the seepage erosion process of cohesive soil, comprising a head control and fluid circulation system, an erosion particle separation and weighing system, and a digital image and data acquisition system, characterized in that: The head control and fluid circulation system includes an upstream storage tank (1) located on a lifting platform (5). The upstream storage tank (1) is connected to a permeation device (3) via a pipeline. The permeation device (3) is connected to an erosion loss particle separation and weighing system via a pipeline. The downstream storage tank (2) is connected to a peristaltic pump (8) via a pipeline. The peristaltic pump (8) is connected to the upstream storage tank (1) via a pipeline. The erosion loss particle separation and weighing system is used to collect eroded fine particles, record mass changes in real time, and realize dynamic tracking of erosion rate. The digital image and data acquisition system is used to record pressure and flow data, and obtain pore structure characteristic parameters by combining image processing.

2. The visualization test device for the seepage erosion process of cohesive soil according to claim 1, characterized in that: The infiltration device (3) includes three areas: a diffusion layer (301), a transparent sample chamber (302), and a liquid collection chamber (303). The diffusion layer (301) is located at the bottom and is filled with gravel. It is isolated from the upper layer by a porous filter plate and has a seepage inlet at the bottom. The transparent sample chamber (302) is located in the middle area and is used to place transparent soil samples. The bottom is covered with a porous filter plate and nylon net to prevent fine particles from being lost, and a rectangular seepage outlet is provided at the top. The liquid collection chamber (303) is located at the top and is used to collect sand-containing fluid and transport it to the erosion loss particle separation and weighing system. The infiltration device (3) has a planar laser emitter (4) on its side. The planar laser emitted by the emitter is used to irradiate the transparent soil sample in the transparent sample chamber (302) to excite fluorescence observation of the distribution of soil particles in the irradiated plane, thereby realizing the visualization observation of the seepage erosion process.

3. The visualization test device for seepage erosion process of cohesive soil according to claim 1, characterized in that: The upstream storage tank (1) includes an overflow tank (101) and a pressure stabilizing tank (102). An L-shaped partition is provided between the overflow tank (101) and the pressure stabilizing tank (102). The bottom of the overflow tank (101) is provided with an overflow tank outlet (1011), and the bottom of the pressure stabilizing tank (102) is provided with a pressure stabilizing tank inlet (1021) and a pressure stabilizing tank outlet (1022). The downstream storage tank (2) is provided with a downstream storage tank inlet (201) and a downstream storage tank outlet (202), and the top is an open structure.

4. The visualization test device for seepage erosion process of cohesive soil according to claim 3, characterized in that: The outlet (1022) of the pressure stabilizing tank is connected to the inlet of the permeation device (3) through the first pipe (14), and the inlet (1021) of the pressure stabilizing tank is connected to the outlet (202) of the downstream storage tank through the second pipe (15); the outlet (1011) of the overflow tank is connected to the inlet (201) of the downstream storage tank through the third pipe (16); the outlet of the liquid collection chamber (303) of the permeation device (3) is connected to one end of the fourth pipe (17), and the other end of the fourth pipe (17) is connected to the erosion and loss particle separation and weighing system.

5. The visualization test device for seepage erosion process of cohesive soil according to claim 4, characterized in that: The upstream storage tank (1) is placed on the lifting platform (5), which is higher than the permeation device (3); the peristaltic pump (8) is located on the second pipeline (15) and is used to pump the solution in the downstream storage tank (2) to the upstream storage tank (1) to achieve fluid circulation.

6. The visualization test device for seepage erosion process of cohesive soil according to claim 4, characterized in that: The particle separation and weighing system includes a support column, a high-precision electronic balance (6), a basket (7), and an iron frame (13). The support column is located outside the downstream storage tank (2), the high-precision electronic balance (6) is placed on top of the support column, the top of the iron frame (13) is connected to the fourth pipe (17), the basket (7) is suspended below the high-precision electronic balance (6), and is located between the opening of the downstream storage tank (2) and the end of the fourth pipe (17) to intercept the particles that seep out. The suspension part of the basket (7) is connected to the tray on the high-precision electronic balance (6).

7. The visualization test device for seepage erosion process of cohesive soil according to claim 6, characterized in that: The iron frame (13) has a clamp on top for fixing the position of the fourth pipe (17), and the height of the clamp is adjustable; the high-precision electronic balance (6) is connected to the computer via a data cable; the basket (7) is lined with a layer of fine nylon netting.

8. The visualization test device for seepage erosion process of cohesive soil according to claim 4, characterized in that: The image and data acquisition system includes a CCD camera (12), a flow meter (10), a pressure sensor (9), and a data acquisition card (11); the CCD camera (12) is located directly in front of the infiltration device (3) and is used to capture the seepage erosion process; the flow meter (10) and the pressure sensor (9) are located on the first pipe (14) and are connected to the data acquisition card via a data cable; the data acquisition card (11) is connected to the computer via a data cable.

9. A test method for a visual test apparatus for the seepage erosion process of cohesive soil as described in any one of claims 1 to 8, characterized in that: It includes the following steps: Step 1: Place the prepared transparent soil sample in the transparent sample chamber (302) of the permeation device (3), and install and adjust the relative positions of the CCD camera (12) and the planar laser emitter (4) with the transparent sample chamber (302); Step 2: Check the pipeline sealing. After confirming that there is no problem, connect the upstream storage tank (1), flow meter (11), pressure sensor (9), infiltration device (3), downstream storage tank (2) and peristaltic pump (8) in sequence to discharge the gas in the first pipeline (14). Adjust the height of the lifting platform (5) so that the upstream storage tank (1) provides a suitable water head for the transparent soil sample. Step 3: Adjust the relative positions of the iron frame (13) and support column with the downstream liquid storage tank (2), install the basket (7) below the high-precision electronic balance (6), place the high-precision electronic balance (6) above the support column, and adjust the end of the outflow fourth pipe (17) to be above the basket (7). Step 4: Connect the flow meter (11) and pressure sensor (9) to the data acquisition card (10), and connect the CCD camera (12), acquisition card (10) and high-precision electronic balance (6) to the computer; Step 5: Turn on the main switch of the laser controller, rotate the power adjustment knob to adjust the laser to a suitable power, turn on the CCD camera (12) and the computer, check the real-time image captured by the camera, and adjust the focal length, position and exposure intensity of the CCD camera. Step 6: Record the seepage erosion and damage process inside the transparent soil sample by controlling the photo interval using a computer, and automatically store the captured images and test data; Step 7: Turn on the peristaltic pump (8) to start the test.

10. The test method of the visualization test device for the seepage erosion process of cohesive soil according to claim 9, characterized in that: The specific process of step 7 is as follows: Under the action of the peristaltic pump (8), the liquid in the downstream storage tank (2) is discharged through the outlet (202) of the downstream storage tank and then introduced into the upstream storage tank (1) through the second pipe (15) and the inlet (1021) of the pressure stabilizing tank. When the liquid in the pressure stabilizing tank (102) begins to overflow, the valve is opened and the liquid in the pressure stabilizing tank (102) is introduced into the permeation device (3) through the outlet (1022) of the pressure stabilizing tank and the first pipe (14). Under the action of permeation, the liquid in the permeation device (3) and the eroded fine particles are introduced into the basket (7) through the collection chamber (303) and the fourth pipe (17). The fine particles flow into the basket (7) for weighing. The liquid flows into the downstream storage tank (2) through the basket (7). The liquid in the overflow tank (101) is introduced into the inlet (201) of the downstream storage tank through the outlet (1011) of the overflow tank and the third pipe (16), thus realizing the closed loop of the fluid.

Images